WorldWideScience

Sample records for grid code based

  1. Coding Model and Mapping Method of Spherical Diamond Discrete Grids Based on Icosahedron

    Directory of Open Access Journals (Sweden)

    LIN Bingxian

    2016-12-01

    Full Text Available Discrete Global Grid(DGG provides a fundamental environment for global-scale spatial data's organization and management. DGG's encoding scheme, which blocks coordinate transformation between different coordination reference frames and reduces the complexity of spatial analysis, contributes a lot to the multi-scale expression and unified modeling of spatial data. Compared with other kinds of DGGs, Diamond Discrete Global Grid(DDGG based on icosahedron is beneficial to the spherical spatial data's integration and expression for much better geometric properties. However, its structure seems more complicated than DDGG on octahedron due to its initial diamond's edges cannot fit meridian and parallel. New challenges are posed when it comes to the construction of hierarchical encoding system and mapping relationship with geographic coordinates. On this issue, this paper presents a DDGG's coding system based on the Hilbert curve and designs conversion methods between codes and geographical coordinates. The study results indicate that this encoding system based on the Hilbert curve can express space scale and location information implicitly with the similarity between DDG and planar grid put into practice, and balances efficiency and accuracy of conversion between codes and geographical coordinates in order to support global massive spatial data's modeling, integrated management and all kinds of spatial analysis.

  2. A gridding method for object-oriented PIC codes

    International Nuclear Information System (INIS)

    Gisler, G.; Peter, W.; Nash, H.; Acquah, J.; Lin, C.; Rine, D.

    1993-01-01

    A simple, rule-based gridding method for object-oriented PIC codes is described which is not only capable of dealing with complicated structures such as multiply-connected regions, but is also computationally faster than classical gridding techniques. Using, these smart grids, vacant cells (e.g., cells enclosed by conductors) will never have to be stored or calculated, thus avoiding the usual situation of having to zero electromagnetic fields within conductors after valuable cpu time has been spent in calculating the fields within these cells in the first place. This object-oriented gridding technique makes use of encapsulating characteristics of actual physical objects (particles, fields, grids, etc.) in C ++ classes and supporting software reuse of these entities through C ++ class inheritance relations. It has been implemented in the form of a simple two-dimensional plasma particle-in-cell code, and forms the initial effort of an AFOSR research project to develop a flexible software simulation environment for particle-in-cell algorithms based on object-oriented technology

  3. Wind power within European grid codes: Evolution, status and outlook

    DEFF Research Database (Denmark)

    Vrana, Til Kristian; Flynn, Damian; Gomez-Lazaro, Emilio

    2018-01-01

    Grid codes are technical specifications that define the requirements for any facility connected to electricity grids. Wind power plants are increasingly facing system stability support requirements similar to conventional power stations, which is to some extent unavoidable, as the share of wind...... power in the generation mix is growing. The adaptation process of grid codes for wind power plants is not yet complete, and grid codes are expected to evolve further in the future. ENTSO-E is the umbrella organization for European TSOs, seen by many as a leader in terms of requirements sophistication...... is largely based on the definitions and provisions set out by ENTSO-E. The main European grid code requirements are outlined here, including also HVDC connections and DC-connected power park modules. The focus is on requirements that are considered particularly relevant for large wind power plants...

  4. Grid connectivity issues and the importance of GCC. [GCC - Grid Code Compliance

    Energy Technology Data Exchange (ETDEWEB)

    Das, A.; Schwartz, M.-K. [GL Renewable Certification, Malleswaram, Bangalore (India)

    2012-07-01

    In India, the wind energy is concentrated in rural areas with a very high penetration. In these cases, the wind power has an increasing influence on the power quality on the grids. Another aspect is the influence of weak grids on the operation of wind turbines. Hence it becomes very much essential to introduce such a strong grid code which is particularly applicable to wind sector and suitable for Indian environmental grid conditions. This paper focuses on different international grid codes and their requirement with regard to the connection of wind farms to the electric power systems to mitigate the grid connectivity issues. The requirements include the ways to achieve voltage and frequency stability in the grid-tied wind power system. In this paper, comparative overview and analysis of the main grid connecting requirements will be conducted, comprising several national and regional codes from many countries where high wind penetration levels have been achieved or are expected in the future. The objective of these requirements is to provide wind farms with the control and regulation capabilities encountered in conventional power plants and are necessary for the safe, reliable and economic operation of the power system. This paper also provides a brief idea on the Grid Code Compliance (GCC) certification procedure implemented by the leading accredited certifying body like Germanischer Lloyd Renewables Certification (GL RC), who checks the conformity of the wind turbines as per region specific grid codes. (Author)

  5. Overview of Grid Codes for Photovoltaic Integration

    DEFF Research Database (Denmark)

    Zheng, Qianwei; Li, Jiaming; Ai, Xiaomeng

    2017-01-01

    The increasing grid-connected photovoltaic (PV) power stations might threaten the safety and stability of power system. Therefore, the grid code is developed for PV power stations to ensure the security of PV integrated power systems. In this paper, requirements for PV power integration in differ...... in different grid codes are first investigated. On this basis, the future advocacy is concluded. Finally, several evaluation indices are proposed to quantify the grid code compliance so that the system operators can validate all these requirements by simulation....

  6. Overview of Grid Codes for Photovoltaic Integration

    DEFF Research Database (Denmark)

    Zheng, Qianwei; Li, Jiaming; Ai, Xiaomeng

    2017-01-01

    The increasing grid-connected photovoltaic (PV) power stations might threaten the safety and stability of power system. Therefore, the grid code is developed for PV power stations to ensure the security of PV integrated power systems. In this paper, requirements for PV power integration in differ......The increasing grid-connected photovoltaic (PV) power stations might threaten the safety and stability of power system. Therefore, the grid code is developed for PV power stations to ensure the security of PV integrated power systems. In this paper, requirements for PV power integration...

  7. Grid Code Requirements for Wind Power Integration

    DEFF Research Database (Denmark)

    Wu, Qiuwei

    2018-01-01

    This chapter reviews the grid code requirements for integration of wind power plants (WPPs). The grid codes reviewed are from the UK, Ireland, Germany, Denmark, Spain, Sweden, the USA, and Canada. Transmission system operators (TSOs) around the world have specified requirements for WPPs under...

  8. SAGE - MULTIDIMENSIONAL SELF-ADAPTIVE GRID CODE

    Science.gov (United States)

    Davies, C. B.

    1994-01-01

    SAGE, Self Adaptive Grid codE, is a flexible tool for adapting and restructuring both 2D and 3D grids. Solution-adaptive grid methods are useful tools for efficient and accurate flow predictions. In supersonic and hypersonic flows, strong gradient regions such as shocks, contact discontinuities, shear layers, etc., require careful distribution of grid points to minimize grid error and produce accurate flow-field predictions. SAGE helps the user obtain more accurate solutions by intelligently redistributing (i.e. adapting) the original grid points based on an initial or interim flow-field solution. The user then computes a new solution using the adapted grid as input to the flow solver. The adaptive-grid methodology poses the problem in an algebraic, unidirectional manner for multi-dimensional adaptations. The procedure is analogous to applying tension and torsion spring forces proportional to the local flow gradient at every grid point and finding the equilibrium position of the resulting system of grid points. The multi-dimensional problem of grid adaption is split into a series of one-dimensional problems along the computational coordinate lines. The reduced one dimensional problem then requires a tridiagonal solver to find the location of grid points along a coordinate line. Multi-directional adaption is achieved by the sequential application of the method in each coordinate direction. The tension forces direct the redistribution of points to the strong gradient region. To maintain smoothness and a measure of orthogonality of grid lines, torsional forces are introduced that relate information between the family of lines adjacent to one another. The smoothness and orthogonality constraints are direction-dependent, since they relate only the coordinate lines that are being adapted to the neighboring lines that have already been adapted. Therefore the solutions are non-unique and depend on the order and direction of adaption. Non-uniqueness of the adapted grid is

  9. Geometrical Approach to the Grid System in the KOPEC Pilot Code

    International Nuclear Information System (INIS)

    Lee, E. J.; Park, C. E.; Lee, S. Y.

    2008-01-01

    KOPEC has been developing a pilot code to analyze two phase flow. The earlier version of the pilot code adopts the geometry with one-dimensional structured mesh system. As the pilot code is required to handle more complex geometries, a systematic geometrical approach to grid system has been introduced. Grid system can be classified as two types; structured grid system and unstructured grid system. The structured grid system is simple to apply but is less flexible than the other. The unstructured grid system is more complicated than the structured grid system. But it is more flexible to model the geometry. Therefore, two types of grid systems are utilized to allow code users simplicity as well as the flexibility

  10. Research and Design in Unified Coding Architecture for Smart Grids

    Directory of Open Access Journals (Sweden)

    Gang Han

    2013-09-01

    Full Text Available Standardized and sharing information platform is the foundation of the Smart Grids. In order to improve the dispatching center information integration of the power grids and achieve efficient data exchange, sharing and interoperability, a unified coding architecture is proposed. The architecture includes coding management layer, coding generation layer, information models layer and application system layer. Hierarchical design makes the whole coding architecture to adapt to different application environments, different interfaces, loosely coupled requirements, which can realize the integration model management function of the power grids. The life cycle and evaluation method of survival of unified coding architecture is proposed. It can ensure the stability and availability of the coding architecture. Finally, the development direction of coding technology of the Smart Grids in future is prospected.

  11. Development of NPP Safety Requirements into Kenya's Grid Codes

    Energy Technology Data Exchange (ETDEWEB)

    Ndirangu, Nguni James; Koo, Chang Choong [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

    2015-10-15

    As presently drafted, Kenya's grid codes do not contain any NPP requirements. Through case studies of selected grid codes, this paper will study frequency, voltage and fault ride through requirements for NPP connection and operation, and offer recommendation of how these requirements can be incorporated in the Kenya's grid codes. Voltage and frequency excursions in Kenya's grid are notably frequently outside the generic requirement and the values observed by the German and UK grid codes. Kenya's grid codes require continuous operation for ±10% of nominal voltage and 45.0 to 52Hz on the grid which poses safety issues for an NPP. Considering stringent NPP connection to grid and operational safety requirements, and the importance of the TSO to NPP safety, more elaborate requirements need to be documented in the Kenya's grid codes. UK and Germany have a history of meeting high standards of nuclear safety and it is therefore recommended that format like the one in Table 1 to 3 should be adopted. Kenya's Grid code considering NPP should have: • Strict rules for voltage variation, that is, -5% to +10% of the nominal voltage • Strict rules for frequency variation, that is, 48Hz to 52Hz of the nominal frequencyand.

  12. Development of NPP Safety Requirements into Kenya's Grid Codes

    International Nuclear Information System (INIS)

    Ndirangu, Nguni James; Koo, Chang Choong

    2015-01-01

    As presently drafted, Kenya's grid codes do not contain any NPP requirements. Through case studies of selected grid codes, this paper will study frequency, voltage and fault ride through requirements for NPP connection and operation, and offer recommendation of how these requirements can be incorporated in the Kenya's grid codes. Voltage and frequency excursions in Kenya's grid are notably frequently outside the generic requirement and the values observed by the German and UK grid codes. Kenya's grid codes require continuous operation for ±10% of nominal voltage and 45.0 to 52Hz on the grid which poses safety issues for an NPP. Considering stringent NPP connection to grid and operational safety requirements, and the importance of the TSO to NPP safety, more elaborate requirements need to be documented in the Kenya's grid codes. UK and Germany have a history of meeting high standards of nuclear safety and it is therefore recommended that format like the one in Table 1 to 3 should be adopted. Kenya's Grid code considering NPP should have: • Strict rules for voltage variation, that is, -5% to +10% of the nominal voltage • Strict rules for frequency variation, that is, 48Hz to 52Hz of the nominal frequencyand

  13. Network Coding Protocols for Smart Grid Communications

    DEFF Research Database (Denmark)

    Prior, Rui; Roetter, Daniel Enrique Lucani; Phulpin, Yannick

    2014-01-01

    We propose a robust network coding protocol for enhancing the reliability and speed of data gathering in smart grids. At the heart of our protocol lies the idea of tunable sparse network coding, which adopts the transmission of sparsely coded packets at the beginning of the transmission process b...

  14. Development of 3-D Flow Analysis Code for Fuel Assembly using Unstructured Grid System

    Energy Technology Data Exchange (ETDEWEB)

    Myong, Hyon Kook; Kim, Jong Eun; Ahn, Jong Ki; Yang, Seung Yong [Kookmin Univ., Seoul (Korea, Republic of)

    2007-03-15

    The flow through a nuclear rod bundle with mixing vanes are very complex and required a suitable turbulence model to be predicted accurately. Final objective of this study is to develop a CFD code for fluid flow and heat transfer analysis in a nuclear fuel assembly using unstructured grid system. In order to develop a CFD code for fluid flow and heat transfer analysis in a nuclear fuel assembly using unstructured grid system, the following researches are made: - Development of numerical algorithm for CFD code's solver - Grid and geometric connectivity data - Development of software(PowerCFD code) for fluid flow and heat transfer analysis in a nuclear fuel assembly using unstructured grid system - Modulation of software(PowerCFD code) - Development of turbulence model - Development of analysis module of RANS/LES hybrid models - Analysis of turbulent flow and heat transfer - Basic study on LES analysis - Development of main frame on pre/post processors based on GUI - Algorithm for fully-developed flow.

  15. Development of 3-D Flow Analysis Code for Fuel Assembly using Unstructured Grid System

    International Nuclear Information System (INIS)

    Myong, Hyon Kook; Kim, Jong Eun; Ahn, Jong Ki; Yang, Seung Yong

    2007-03-01

    The flow through a nuclear rod bundle with mixing vanes are very complex and required a suitable turbulence model to be predicted accurately. Final objective of this study is to develop a CFD code for fluid flow and heat transfer analysis in a nuclear fuel assembly using unstructured grid system. In order to develop a CFD code for fluid flow and heat transfer analysis in a nuclear fuel assembly using unstructured grid system, the following researches are made: - Development of numerical algorithm for CFD code's solver - Grid and geometric connectivity data - Development of software(PowerCFD code) for fluid flow and heat transfer analysis in a nuclear fuel assembly using unstructured grid system - Modulation of software(PowerCFD code) - Development of turbulence model - Development of analysis module of RANS/LES hybrid models - Analysis of turbulent flow and heat transfer - Basic study on LES analysis - Development of main frame on pre/post processors based on GUI - Algorithm for fully-developed flow

  16. Technical and operational organisation of the 'Swiss Marketplace': GridCode CH

    International Nuclear Information System (INIS)

    Imhof, K.; Baumann, R.

    2001-01-01

    This article describes the minimum requirements placed on the operators of electricity grids by the planned Swiss Electricity Market Law. These are compiled in the Swiss Grid Code - GridCode CH. The various players in an open electricity market such as generating companies, power brokers, those responsible for balance groups, grid operators, system co-ordinators, the operators of fine distribution networks and the final consumer and the roles they play are examined. The history of the development of the Grid Code, which contains technical and operational regulations for the successful co-operation of the market players, is reviewed. The contractual obligations of the partners involved and, in particular, regulations concerning metering, measured value designation and the provision of data are discussed

  17. Grid-based Parallel Data Streaming Implemented for the Gyrokinetic Toroidal Code

    International Nuclear Information System (INIS)

    Klasky, S.; Ethier, S.; Lin, Z.; Martins, K.; McCune, D.; Samtaney, R.

    2003-01-01

    We have developed a threaded parallel data streaming approach using Globus to transfer multi-terabyte simulation data from a remote supercomputer to the scientist's home analysis/visualization cluster, as the simulation executes, with negligible overhead. Data transfer experiments show that this concurrent data transfer approach is more favorable compared with writing to local disk and then transferring this data to be post-processed. The present approach is conducive to using the grid to pipeline the simulation with post-processing and visualization. We have applied this method to the Gyrokinetic Toroidal Code (GTC), a 3-dimensional particle-in-cell code used to study microturbulence in magnetic confinement fusion from first principles plasma theory

  18. Review of grid code frequency requirements for wind farms

    Energy Technology Data Exchange (ETDEWEB)

    El Itani, S.; Joos, G. [McGill Univ., Montreal, PQ (Canada)

    2010-07-01

    This paper presented frequency grid code requirements for the connection of wind farms to power systems at the high voltage level. The necessity of ensuring that connected wind farms will contribute to the secure operation of the power system in a manner similar to conventional generators has led to the development of several grid code requirements (GCRs) for the integration of wind farms to the grid. These provisions are in place to ensure that wind projects do not negatively impact system stability and reliability. A comparative overview of the main requirements was conducted, looking at national and regional codes from areas with high wind penetration levels. These requirements provide wind farms with the control and regulation capabilities encountered in conventional power plants, which is necessary for the safe, reliable, and economic operation of the system. These requirements have heavily influenced the development of wind turbine generator (WTGs) technology over the last decade. It was concluded that modern WTGs are capable of meeting all the requirements thus far set for active power and ramp rates, extended frequency range, and frequency response required for functional incorporation into modern power grids. 17 refs., 6 tabs., 11 figs.

  19. Grid code requirements for wind power generation

    International Nuclear Information System (INIS)

    Djagarov, N.; Filchev, S.; Grozdev, Z.; Bonev, M.

    2011-01-01

    In this paper production data of wind power in Europe and Bulgaria and plans for their development within 2030 are reviewed. The main characteristics of wind generators used in Bulgaria are listed. A review of the grid code in different European countries, which regulate the requirements for renewable sources, is made. European recommendations for requirements harmonization are analyzed. Suggestions for the Bulgarian gird code are made

  20. GAIA: A 2-D Curvilinear moving grid hydrodynamic code

    International Nuclear Information System (INIS)

    Jourdren, H.

    1987-02-01

    The GAIA computer code is developed for time dependent, compressible, multimaterial fluid flow problems, to overcome some drawbacks of traditional 2-D Lagrangian codes. The initial goals of robustness, entropy accuracies, efficiency in presence of large interfacial slip, have already been achieved. The general GODUNOV approach is applied to an arbitrary time varying control-volume formulation. We review in this paper the Riemann solver, the GODUNOV cartesian and curvilinear moving grid schemes and an efficient grid generation algorithm. We finally outline a possible second order accuracy extension

  1. Network Coding Opportunities for Wireless Grids Formed by Mobile Devices

    DEFF Research Database (Denmark)

    Nielsen, Karsten Fyhn; Madsen, Tatiana Kozlova; Fitzek, Frank

    2008-01-01

    Wireless grids have potential in sharing communication, computational and storage resources making these networks more powerful, more robust, and less cost intensive. However, to enjoy the benefits of cooperative resource sharing, a number of issues should be addressed and the cost of the wireless...... link should be taken into account. We focus on the question how nodes can efficiently communicate and distribute data in a wireless grid. We show the potential of a network coding approach when nodes have the possibility to combine packets thus increasing the amount of information per transmission. Our...... implementation demonstrates the feasibility of network coding for wireless grids formed by mobile devices....

  2. The research on multi-projection correction based on color coding grid array

    Science.gov (United States)

    Yang, Fan; Han, Cheng; Bai, Baoxing; Zhang, Chao; Zhao, Yunxiu

    2017-10-01

    There are many disadvantages such as lower timeliness, greater manual intervention in multi-channel projection system, in order to solve the above problems, this paper proposes a multi-projector correction technology based on color coding grid array. Firstly, a color structured light stripe is generated by using the De Bruijn sequences, then meshing the feature information of the color structured light stripe image. We put the meshing colored grid intersection as the center of the circle, and build a white solid circle as the feature sample set of projected images. It makes the constructed feature sample set not only has the perceptual localization, but also has good noise immunity. Secondly, we establish the subpixel geometric mapping relationship between the projection screen and the individual projectors by using the structure of light encoding and decoding based on the color array, and the geometrical mapping relation is used to solve the homography matrix of each projector. Lastly the brightness inconsistency of the multi-channel projection overlap area is seriously interfered, it leads to the corrected image doesn't fit well with the observer's visual needs, and we obtain the projection display image of visual consistency by using the luminance fusion correction algorithm. The experimental results show that this method not only effectively solved the problem of distortion of multi-projection screen and the issue of luminance interference in overlapping region, but also improved the calibration efficient of multi-channel projective system and reduced the maintenance cost of intelligent multi-projection system.

  3. GRID-BASED EXPLORATION OF COSMOLOGICAL PARAMETER SPACE WITH SNAKE

    International Nuclear Information System (INIS)

    Mikkelsen, K.; Næss, S. K.; Eriksen, H. K.

    2013-01-01

    We present a fully parallelized grid-based parameter estimation algorithm for investigating multidimensional likelihoods called Snake, and apply it to cosmological parameter estimation. The basic idea is to map out the likelihood grid-cell by grid-cell according to decreasing likelihood, and stop when a certain threshold has been reached. This approach improves vastly on the 'curse of dimensionality' problem plaguing standard grid-based parameter estimation simply by disregarding grid cells with negligible likelihood. The main advantages of this method compared to standard Metropolis-Hastings Markov Chain Monte Carlo methods include (1) trivial extraction of arbitrary conditional distributions; (2) direct access to Bayesian evidences; (3) better sampling of the tails of the distribution; and (4) nearly perfect parallelization scaling. The main disadvantage is, as in the case of brute-force grid-based evaluation, a dependency on the number of parameters, N par . One of the main goals of the present paper is to determine how large N par can be, while still maintaining reasonable computational efficiency; we find that N par = 12 is well within the capabilities of the method. The performance of the code is tested by comparing cosmological parameters estimated using Snake and the WMAP-7 data with those obtained using CosmoMC, the current standard code in the field. We find fully consistent results, with similar computational expenses, but shorter wall time due to the perfect parallelization scheme

  4. Schnek: A C++ library for the development of parallel simulation codes on regular grids

    Science.gov (United States)

    Schmitz, Holger

    2018-05-01

    A large number of algorithms across the field of computational physics are formulated on grids with a regular topology. We present Schnek, a library that enables fast development of parallel simulations on regular grids. Schnek contains a number of easy-to-use modules that greatly reduce the amount of administrative code for large-scale simulation codes. The library provides an interface for reading simulation setup files with a hierarchical structure. The structure of the setup file is translated into a hierarchy of simulation modules that the developer can specify. The reader parses and evaluates mathematical expressions and initialises variables or grid data. This enables developers to write modular and flexible simulation codes with minimal effort. Regular grids of arbitrary dimension are defined as well as mechanisms for defining physical domain sizes, grid staggering, and ghost cells on these grids. Ghost cells can be exchanged between neighbouring processes using MPI with a simple interface. The grid data can easily be written into HDF5 files using serial or parallel I/O.

  5. Development of a multi-grid FDTD code for three-dimensional simulation of large microwave sintering experiments

    Energy Technology Data Exchange (ETDEWEB)

    White, M.J.; Iskander, M.F. [Univ. of Utah, Salt Lake City, UT (United States). Electrical Engineering Dept.; Kimrey, H.D. [Oak Ridge National Lab., TN (United States)

    1996-12-31

    The Finite-Difference Time-Domain (FDTD) code available at the University of Utah has been used to simulate sintering of ceramics in single and multimode cavities, and many useful results have been reported in literature. More detailed and accurate results, specifically around and including the ceramic sample, are often desired to help evaluate the adequacy of the heating procedure. In electrically large multimode cavities, however, computer memory requirements limit the number of the mathematical cells, and the desired resolution is impractical to achieve due to limited computer resources. Therefore, an FDTD algorithm which incorporates multiple-grid regions with variable-grid sizes is required to adequately perform the desired simulations. In this paper the authors describe the development of a three-dimensional multi-grid FDTD code to help focus a large number of cells around the desired region. Test geometries were solved using a uniform-grid and the developed multi-grid code to help validate the results from the developed code. Results from these comparisons, as well as the results of comparisons between the developed FDTD code and other available variable-grid codes are presented. In addition, results from the simulation of realistic microwave sintering experiments showed improved resolution in critical sites inside the three-dimensional sintering cavity. With the validation of the FDTD code, simulations were performed for electrically large, multimode, microwave sintering cavities to fully demonstrate the advantages of the developed multi-grid FDTD code.

  6. Preprocessor that Enables the Use of GridProTM Grids for Unsteady Reynolds-Averaged Navier-Stokes Code TURBO

    Science.gov (United States)

    Shyam, Vikram

    2010-01-01

    A preprocessor for the Computational Fluid Dynamics (CFD) code TURBO has been developed and tested. The preprocessor converts grids produced by GridPro (Program Development Company (PDC)) into a format readable by TURBO and generates the necessary input files associated with the grid. The preprocessor also generates information that enables the user to decide how to allocate the computational load in a multiple block per processor scenario.

  7. Wind Farm Grid Integration Using VSC Based HVDC Transmission - An Overview

    DEFF Research Database (Denmark)

    Chaudhary, Sanjay Kumar; Teodorescu, Remus; Rodriguez, Pedro

    2008-01-01

    The paper gives an overview of HVAC and HVDC connection of wind farm to the grid, with an emphasis on Voltage Source Converter (VSC)-based HVDC for large wind farms requiring long distance cable connection. Flexible control capabilities of a VSC-based HVDC system enables smooth integration of wind...... farm into the power grid network while meeting the Grid Code Requirements (GCR). Operation of a wind farm with VSC-based HVDC connection is described....

  8. GRID-BASED EXPLORATION OF COSMOLOGICAL PARAMETER SPACE WITH SNAKE

    Energy Technology Data Exchange (ETDEWEB)

    Mikkelsen, K.; Næss, S. K.; Eriksen, H. K., E-mail: kristin.mikkelsen@astro.uio.no [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, NO-0315 Oslo (Norway)

    2013-11-10

    We present a fully parallelized grid-based parameter estimation algorithm for investigating multidimensional likelihoods called Snake, and apply it to cosmological parameter estimation. The basic idea is to map out the likelihood grid-cell by grid-cell according to decreasing likelihood, and stop when a certain threshold has been reached. This approach improves vastly on the 'curse of dimensionality' problem plaguing standard grid-based parameter estimation simply by disregarding grid cells with negligible likelihood. The main advantages of this method compared to standard Metropolis-Hastings Markov Chain Monte Carlo methods include (1) trivial extraction of arbitrary conditional distributions; (2) direct access to Bayesian evidences; (3) better sampling of the tails of the distribution; and (4) nearly perfect parallelization scaling. The main disadvantage is, as in the case of brute-force grid-based evaluation, a dependency on the number of parameters, N{sub par}. One of the main goals of the present paper is to determine how large N{sub par} can be, while still maintaining reasonable computational efficiency; we find that N{sub par} = 12 is well within the capabilities of the method. The performance of the code is tested by comparing cosmological parameters estimated using Snake and the WMAP-7 data with those obtained using CosmoMC, the current standard code in the field. We find fully consistent results, with similar computational expenses, but shorter wall time due to the perfect parallelization scheme.

  9. Overview of Recent Grid Codes for Wind Power Integration

    DEFF Research Database (Denmark)

    Altin, Müfit; Göksu, Ömer; Teodorescu, Remus

    2010-01-01

    As wind power penetration level increases, power system operators are challenged by the penetration impacts to maintain reliability and stability of power system. Therefore, grid codes are being published and continuously updated by transmission system operators of the countries. In this paper...

  10. Stoplight Grid: a color-coded visual system for per diem staff assignment.

    Science.gov (United States)

    Ernst, P

    1989-02-01

    What is the best way to appropriately assign per diem nursing personnel? The author describes a systematic approach to per diem staff assignment called the Stoplight Grid. The Stoplight Grid correlates staff skills and preferences with unit needs and integrates this data into a color-coded system for staff assignment.

  11. Near-Body Grid Adaption for Overset Grids

    Science.gov (United States)

    Buning, Pieter G.; Pulliam, Thomas H.

    2016-01-01

    A solution adaption capability for curvilinear near-body grids has been implemented in the OVERFLOW overset grid computational fluid dynamics code. The approach follows closely that used for the Cartesian off-body grids, but inserts refined grids in the computational space of original near-body grids. Refined curvilinear grids are generated using parametric cubic interpolation, with one-sided biasing based on curvature and stretching ratio of the original grid. Sensor functions, grid marking, and solution interpolation tasks are implemented in the same fashion as for off-body grids. A goal-oriented procedure, based on largest error first, is included for controlling growth rate and maximum size of the adapted grid system. The adaption process is almost entirely parallelized using MPI, resulting in a capability suitable for viscous, moving body simulations. Two- and three-dimensional examples are presented.

  12. Code Shift: Grid Specifications and Dynamic Wind Turbine Models

    DEFF Research Database (Denmark)

    Ackermann, Thomas; Ellis, Abraham; Fortmann, Jens

    2013-01-01

    Grid codes (GCs) and dynamic wind turbine (WT) models are key tools to allow increasing renewable energy penetration without challenging security of supply. In this article, the state of the art and the further development of both tools are discussed, focusing on the European and North American e...

  13. Improved numerical grid generation techniques for the B2 edge plasma code

    International Nuclear Information System (INIS)

    Stotler, D.P.; Coster, D.P.

    1992-06-01

    Techniques used to generate grids for edge fluid codes such as B2 from numerically computed equilibria are discussed. Fully orthogonal, numerically derived grids closely resembling analytically prescribed meshes can be obtained. But, the details of the poloidal field can vary, yielding significantly different plasma parameters in the simulations. The magnitude of these differences is consistent with the predictions of an analytic model of the scrape-off layer. Both numerical and analytic grids are insensitive to changes in their defining parameters. Methods for implementing nonorthogonal boundaries in these meshes are also presented; they differ slightly from those required for fully orthogonal grids

  14. The performance test of anti-scattering x-ray grid with inclined shielding material by MCNP code simulation

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Jun Woo; Kim, Hee Reyoung [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2016-06-15

    The scattered photons cause reduction of the contrast of radiographic image and it results in the degradation of the quality of the image. In order to acquire better quality image, an anti-scattering x-ray gird should be equipped in radiography system. The X-ray anti-scattering grid of the inclined type based on the hybrid concept for that of parallel and focused type was tested by MCNP code. The MCNPX 2.7.0 was used for the simulation based test. The geometry for the test was based on the IEC 60627 which was an international standard for diagnostic X-ray imaging equipment-Characteristics of general purpose and mammographic anti-scatter grids. The performance of grids with four inclined shielding material types was compared with that of the parallel type. The grid with completely tapered type the best performance where there were little performance difference according to the degree of inclination.

  15. Camera Coverage Estimation Based on Multistage Grid Subdivision

    Directory of Open Access Journals (Sweden)

    Meizhen Wang

    2017-04-01

    Full Text Available Visual coverage is one of the most important quality indexes for depicting the usability of an individual camera or camera network. It is the basis for camera network deployment, placement, coverage-enhancement, planning, etc. Precision and efficiency are critical influences on applications, especially those involving several cameras. This paper proposes a new method to efficiently estimate superior camera coverage. First, the geographic area that is covered by the camera and its minimum bounding rectangle (MBR without considering obstacles is computed using the camera parameters. Second, the MBR is divided into grids using the initial grid size. The status of the four corners of each grid is estimated by a line of sight (LOS algorithm. If the camera, considering obstacles, covers a corner, the status is represented by 1, otherwise by 0. Consequently, the status of a grid can be represented by a code that is a combination of 0s or 1s. If the code is not homogeneous (not four 0s or four 1s, the grid will be divided into four sub-grids until the sub-grids are divided into a specific maximum level or their codes are homogeneous. Finally, after performing the process above, total camera coverage is estimated according to the size and status of all grids. Experimental results illustrate that the proposed method’s accuracy is determined by the method that divided the coverage area into the smallest grids at the maximum level, while its efficacy is closer to the method that divided the coverage area into the initial grids. It considers both efficiency and accuracy. The initial grid size and maximum level are two critical influences on the proposed method, which can be determined by weighing efficiency and accuracy.

  16. Development of a Cartesian grid based CFD solver (CARBS)

    International Nuclear Information System (INIS)

    Vaidya, A.M.; Maheshwari, N.K.; Vijayan, P.K.

    2013-12-01

    Formulation for 3D transient incompressible CFD solver is developed. The solution of variable property, laminar/turbulent, steady/unsteady, single/multi specie, incompressible with heat transfer in complex geometry will be obtained. The formulation can handle a flow system in which any number of arbitrarily shaped solid and fluid regions are present. The solver is based on the use of Cartesian grids. A method is proposed to handle complex shaped objects and boundaries on Cartesian grids. Implementation of multi-material, different types of boundary conditions, thermo physical properties is also considered. The proposed method is validated by solving two test cases. 1 st test case is that of lid driven flow in inclined cavity. 2 nd test case is the flow over cylinder. The 1 st test case involved steady internal flow subjected to WALL boundaries. The 2 nd test case involved unsteady external flow subjected to INLET, OUTLET and FREE-SLIP boundary types. In both the test cases, non-orthogonal geometry was involved. It was found that, under such a wide conditions, the Cartesian grid based code was found to give results which were matching well with benchmark data. Convergence characteristics are excellent. In all cases, the mass residue was converged to 1E-8. Based on this, development of 3D general purpose code based on the proposed approach can be taken up. (author)

  17. Mapping of grid faults and grid codes

    DEFF Research Database (Denmark)

    Iov, F.; Hansen, Anca Daniela; Sørensen, Poul Ejnar

    loads of wind turbines. The goal is also to clarify and define possible new directions in the certification process of power plant wind turbines, namely wind turbines, which participate actively in the stabilisation of power systems. Practical experience shows that there is a need...... challenges for the design of both the electrical system and the mechanical structure of wind turbines. An overview over the frequency of grid faults and the grid connection requirements in different relevant countries is done in this report. The most relevant study cases for the quantification of the loads......The present report is a part of the research project ''Grid fault and designbasis for wind turbine'' supported by Energinet.dk through the grant PSO F&U 6319. The objective of this project is to investigate into the consequences of the new grid connection requirements for the fatigue and extreme...

  18. Mapping of grid faults and grid codes

    DEFF Research Database (Denmark)

    Iov, Florin; Hansen, A.D.; Sørensen, P.

    loads of wind turbines. The goal is also to clarify and define possible new directions in the certification process of power plant wind turbines, namely wind turbines, which participate actively in the stabilisation of power systems. Practical experience shows that there is a need...... challenges for the design of both the electrical system and the mechanical structure of wind turbines. An overview over the frequency of grid faults and the grid connection requirements in different relevant countries is done in this report. The most relevant study cases for the quantification of the loads......The present report is a part of the research project "Grid fault and design basis for wind turbine" supported by Energinet.dk through the grant PSO F&U 6319. The objective of this project is to investigate into the consequences of the new grid connection requirements for the fatigue and extreme...

  19. mGrid: A load-balanced distributed computing environment for the remote execution of the user-defined Matlab code

    Directory of Open Access Journals (Sweden)

    Almeida Jonas S

    2006-03-01

    Full Text Available Abstract Background Matlab, a powerful and productive language that allows for rapid prototyping, modeling and simulation, is widely used in computational biology. Modeling and simulation of large biological systems often require more computational resources then are available on a single computer. Existing distributed computing environments like the Distributed Computing Toolbox, MatlabMPI, Matlab*G and others allow for the remote (and possibly parallel execution of Matlab commands with varying support for features like an easy-to-use application programming interface, load-balanced utilization of resources, extensibility over the wide area network, and minimal system administration skill requirements. However, all of these environments require some level of access to participating machines to manually distribute the user-defined libraries that the remote call may invoke. Results mGrid augments the usual process distribution seen in other similar distributed systems by adding facilities for user code distribution. mGrid's client-side interface is an easy-to-use native Matlab toolbox that transparently executes user-defined code on remote machines (i.e. the user is unaware that the code is executing somewhere else. Run-time variables are automatically packed and distributed with the user-defined code and automated load-balancing of remote resources enables smooth concurrent execution. mGrid is an open source environment. Apart from the programming language itself, all other components are also open source, freely available tools: light-weight PHP scripts and the Apache web server. Conclusion Transparent, load-balanced distribution of user-defined Matlab toolboxes and rapid prototyping of many simple parallel applications can now be done with a single easy-to-use Matlab command. Because mGrid utilizes only Matlab, light-weight PHP scripts and the Apache web server, installation and configuration are very simple. Moreover, the web-based

  20. mGrid: a load-balanced distributed computing environment for the remote execution of the user-defined Matlab code.

    Science.gov (United States)

    Karpievitch, Yuliya V; Almeida, Jonas S

    2006-03-15

    Matlab, a powerful and productive language that allows for rapid prototyping, modeling and simulation, is widely used in computational biology. Modeling and simulation of large biological systems often require more computational resources then are available on a single computer. Existing distributed computing environments like the Distributed Computing Toolbox, MatlabMPI, Matlab*G and others allow for the remote (and possibly parallel) execution of Matlab commands with varying support for features like an easy-to-use application programming interface, load-balanced utilization of resources, extensibility over the wide area network, and minimal system administration skill requirements. However, all of these environments require some level of access to participating machines to manually distribute the user-defined libraries that the remote call may invoke. mGrid augments the usual process distribution seen in other similar distributed systems by adding facilities for user code distribution. mGrid's client-side interface is an easy-to-use native Matlab toolbox that transparently executes user-defined code on remote machines (i.e. the user is unaware that the code is executing somewhere else). Run-time variables are automatically packed and distributed with the user-defined code and automated load-balancing of remote resources enables smooth concurrent execution. mGrid is an open source environment. Apart from the programming language itself, all other components are also open source, freely available tools: light-weight PHP scripts and the Apache web server. Transparent, load-balanced distribution of user-defined Matlab toolboxes and rapid prototyping of many simple parallel applications can now be done with a single easy-to-use Matlab command. Because mGrid utilizes only Matlab, light-weight PHP scripts and the Apache web server, installation and configuration are very simple. Moreover, the web-based infrastructure of mGrid allows for it to be easily extensible over

  1. Grid Generation Techniques Utilizing the Volume Grid Manipulator

    Science.gov (United States)

    Alter, Stephen J.

    1998-01-01

    This paper presents grid generation techniques available in the Volume Grid Manipulation (VGM) code. The VGM code is designed to manipulate existing line, surface and volume grids to improve the quality of the data. It embodies an easy to read rich language of commands that enables such alterations as topology changes, grid adaption and smoothing. Additionally, the VGM code can be used to construct simplified straight lines, splines, and conic sections which are common curves used in the generation and manipulation of points, lines, surfaces and volumes (i.e., grid data). These simple geometric curves are essential in the construction of domain discretizations for computational fluid dynamic simulations. By comparison to previously established methods of generating these curves interactively, the VGM code provides control of slope continuity and grid point-to-point stretchings as well as quick changes in the controlling parameters. The VGM code offers the capability to couple the generation of these geometries with an extensive manipulation methodology in a scripting language. The scripting language allows parametric studies of a vehicle geometry to be efficiently performed to evaluate favorable trends in the design process. As examples of the powerful capabilities of the VGM code, a wake flow field domain will be appended to an existing X33 Venturestar volume grid; negative volumes resulting from grid expansions to enable flow field capture on a simple geometry, will be corrected; and geometrical changes to a vehicle component of the X33 Venturestar will be shown.

  2. Radiation Coupling with the FUN3D Unstructured-Grid CFD Code

    Science.gov (United States)

    Wood, William A.

    2012-01-01

    The HARA radiation code is fully-coupled to the FUN3D unstructured-grid CFD code for the purpose of simulating high-energy hypersonic flows. The radiation energy source terms and surface heat transfer, under the tangent slab approximation, are included within the fluid dynamic ow solver. The Fire II flight test, at the Mach-31 1643-second trajectory point, is used as a demonstration case. Comparisons are made with an existing structured-grid capability, the LAURA/HARA coupling. The radiative surface heat transfer rates from the present approach match the benchmark values within 6%. Although radiation coupling is the focus of the present work, convective surface heat transfer rates are also reported, and are seen to vary depending upon the choice of mesh connectivity and FUN3D ux reconstruction algorithm. On a tetrahedral-element mesh the convective heating matches the benchmark at the stagnation point, but under-predicts by 15% on the Fire II shoulder. Conversely, on a mixed-element mesh the convective heating over-predicts at the stagnation point by 20%, but matches the benchmark away from the stagnation region.

  3. Instability of Wind Turbine Converters during Current Injection to Low Voltage Grid Faults and PLL Frequency Based Stability Solution

    DEFF Research Database (Denmark)

    Göksu, Ömer; Teodorescu, Remus; Bak, Claus Leth

    2014-01-01

    In recent grid codes for wind power integration, wind turbines are required to stay connected during grid faults even when the grid voltage drops down to zero; and also to inject reactive current in proportion to the voltage drop. However, a physical fact, instability of grid-connected converters...... during current injection to very low (close to zero) voltage faults, has been omitted, i.e., failed to be noticed in the previous wind power studies and grid code revisions. In this paper, the instability of grid side converters of wind turbines defined as loss of synchronism (LOS), where the wind...... turbines lose synchronism with the grid fundamental frequency (e.g., 50 Hz) during very deep voltage sags, is explored with its theory, analyzed and a novel stability solution based on PLL frequency is proposed; and both are verified with power system simulations and by experiments on a grid...

  4. Mapping of grid faults and grid codes[Wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Iov, F. [Aalborg Univ., Inst. of Energy Technology (Denmark); Hansen, Anca D.; Soerensen, Poul; Cutululis, N.A. [Risoe National Lab. - DTU, Wind Enegy Dept., Roskilde (Denmark)

    2007-06-15

    The objective of this project is to investigate into the consequences of the new grid connection requirements for the fatigue and extreme loads of wind turbines. The goal is also to clarify and define possible new directions in the certification process of power plant wind turbines, namely wind turbines, which participate actively in the stabilisation of power systems. Practical experience shows that there is a need for such investigations. The grid connection requirements for wind turbines have increased significantly during the last 5-10 years. Especially the requirements for wind turbines to stay connected to the grid during and after voltage sags, imply potential challenges in the design of wind turbines. These requirements pose challenges for the design of both the electrical system and the mechanical structure of wind turbines. An overview over the frequency of grid faults and the grid connection requirements in different relevant countries is done in this report. The most relevant study cases for the quantification of the loads' impact on the wind turbines' lifetime are defined. The goal of this report is to present a mapping of different grid fault types and their frequency in different countries. The report provides also a detailed overview of the Low Voltage Ride-Through Capabilities for wind turbines in different relevant countries. The most relevant study cases for the quantification of the loads' impact on the wind turbines' lifetime are defined. (au)

  5. Grid-code of Croatian power system

    International Nuclear Information System (INIS)

    Toljan, I.; Mesic, M.; Kalea, M.; Koscak, Z.

    2003-01-01

    Grid Rules by the Croatian Electricity Utility deal with the control and usage of the Croatian power system's transmission and distribution grid. Furthermore, these rules include obligations and permissions of power grid users and owners, with the aim of a reliable electricity supply.(author)

  6. Parallel Implementation of the Multi-Dimensional Spectral Code SPECT3D on large 3D grids.

    Science.gov (United States)

    Golovkin, Igor E.; Macfarlane, Joseph J.; Woodruff, Pamela R.; Pereyra, Nicolas A.

    2006-10-01

    The multi-dimensional collisional-radiative, spectral analysis code SPECT3D can be used to study radiation from complex plasmas. SPECT3D can generate instantaneous and time-gated images and spectra, space-resolved and streaked spectra, which makes it a valuable tool for post-processing hydrodynamics calculations and direct comparison between simulations and experimental data. On large three dimensional grids, transporting radiation along lines of sight (LOS) requires substantial memory and CPU resources. Currently, the parallel option in SPECT3D is based on parallelization over photon frequencies and allows for a nearly linear speed-up for a variety of problems. In addition, we are introducing a new parallel mechanism that will greatly reduce memory requirements. In the new implementation, spatial domain decomposition will be utilized allowing transport along a LOS to be performed only on the mesh cells the LOS crosses. The ability to operate on a fraction of the grid is crucial for post-processing the results of large-scale three-dimensional hydrodynamics simulations. We will present a parallel implementation of the code and provide a scalability study performed on a Linux cluster.

  7. Common Envelope Light Curves. I. Grid-code Module Calibration

    Energy Technology Data Exchange (ETDEWEB)

    Galaviz, Pablo; Marco, Orsola De; Staff, Jan E.; Iaconi, Roberto [Department of Physics and Astronomy, Macquarie University, Sydney, NSW (Australia); Passy, Jean-Claude, E-mail: Pablo.Galaviz@me.com [Argelander-Institut für Astronomie, Auf dem Hügel 71, D-53121 Bonn (Germany)

    2017-04-01

    The common envelope (CE) binary interaction occurs when a star transfers mass onto a companion that cannot fully accrete it. The interaction can lead to a merger of the two objects or to a close binary. The CE interaction is the gateway of all evolved compact binaries, all stellar mergers, and likely many of the stellar transients witnessed to date. CE simulations are needed to understand this interaction and to interpret stars and binaries thought to be the byproduct of this stage. At this time, simulations are unable to reproduce the few observational data available and several ideas have been put forward to address their shortcomings. The need for more definitive simulation validation is pressing and is already being fulfilled by observations from time-domain surveys. In this article, we present an initial method and its implementation for post-processing grid-based CE simulations to produce the light curve so as to compare simulations with upcoming observations. Here we implemented a zeroth order method to calculate the light emitted from CE hydrodynamic simulations carried out with the 3D hydrodynamic code Enzo used in unigrid mode. The code implements an approach for the computation of luminosity in both optically thick and optically thin regimes and is tested using the first 135 days of the CE simulation of Passy et al., where a 0.8  M {sub ⊙} red giant branch star interacts with a 0.6  M {sub ⊙} companion. This code is used to highlight two large obstacles that need to be overcome before realistic light curves can be calculated. We explain the nature of these problems and the attempted solutions and approximations in full detail to enable the next step to be identified and implemented. We also discuss our simulation in relation to recent data of transients identified as CE interactions.

  8. Suggested Grid Code Modifications to Ensure Wide-Scale Adoption of Photovoltaic Energy in Distributed Power Generation Systems

    DEFF Research Database (Denmark)

    Yang, Yongheng; Enjeti, Prasad; Blaabjerg, Frede

    2013-01-01

    Current grid standards seem to largely require low power (e.g. several kilowatts) single-phase photovoltaic (PV) systems to operate at unity power factor with maximum power point tracking, and disconnect from the grid under grid faults. However, in case of a wide-scale penetration of single......-phase PV systems in the distributed grid, the disconnection under grid faults can contribute to: a) voltage flickers, b) power outages, and c) system instability. In this paper, grid code modifications are explored for wide-scale adoption of PV systems in the distribution grid. More recently, Italy...... and Japan, have undertaken a major review of standards for PV power conversion systems connected to low voltage networks. In view of this, the importance of low voltage ride-through for single-phase PV power systems under grid faults along with reactive power injection is studied in this paper. Three...

  9. Feasibility and its characteristics of CO2 laser micromachining-based PMMA anti-scattering grid estimated by MCNP code simulation.

    Science.gov (United States)

    Bae, Jun Woo; Kim, Hee Reyoung

    2018-01-01

    Anti-scattering grid has been used to improve the image quality. However, applying a commonly used linear or parallel grid would cause image distortion, and focusing grid also requires a precise fabrication technology, which is expensive. To investigate and analyze whether using CO2 laser micromachining-based PMMA anti-scattering grid can improve the performance of the grid at a lower cost. Thus, improvement of grid performance would result in improvement of image quality. The cross-sectional shape of CO2 laser machined PMMA is similar to alphabet 'V'. The performance was characterized by contrast improvement factor (CIF) and Bucky. Four types of grid were tested, which include thin parallel, thick parallel, 'V'-type and 'inverse V'-type of grid. For a Bucky factor of 2.1, the CIF of the grid with both the "V" and inverse "V" had a value of 1.53, while the thick and thick parallel types had values of 1.43 and 1.65, respectively. The 'V' shape grid manufacture by CO2 laser micromachining showed higher CIF than parallel one, which had same shielding material channel width. It was thought that the 'V' shape grid would be replacement to the conventional parallel grid if it is hard to fabricate the high-aspect-ratio grid.

  10. Coupling an analytical description of anti-scatter grids with simulation software of radiographic systems using Monte Carlo code

    International Nuclear Information System (INIS)

    Rinkel, J.; Dinten, J.M.; Tabary, J.

    2004-01-01

    The use of focused anti-scatter grids on digital radiographic systems with two-dimensional detectors produces acquisitions with a decreased scatter to primary ratio and thus improved contrast and resolution. Simulation software is of great interest in optimizing grid configuration according to a specific application. Classical simulators are based on complete detailed geometric descriptions of the grid. They are accurate but very time consuming since they use Monte Carlo code to simulate scatter within the high-frequency grids. We propose a new practical method which couples an analytical simulation of the grid interaction with a radiographic system simulation program. First, a two dimensional matrix of probability depending on the grid is created offline, in which the first dimension represents the angle of impact with respect to the normal to the grid lines and the other the energy of the photon. This matrix of probability is then used by the Monte Carlo simulation software in order to provide the final scattered flux image. To evaluate the gain of CPU time, we define the increasing factor as the increase of CPU time of the simulation with as opposed to without the grid. Increasing factors were calculated with the new model and with classical methods representing the grid with its CAD model as part of the object. With the new method, increasing factors are shorter by one to two orders of magnitude compared with the second one. These results were obtained with a difference in calculated scatter of less than five percent between the new and the classical method. (authors)

  11. Impact of Distributed Generation Grid Code Requirements on Islanding Detection in LV Networks

    Directory of Open Access Journals (Sweden)

    Fabio Bignucolo

    2017-01-01

    Full Text Available The recent growing diffusion of dispersed generation in low voltage (LV distribution networks is entailing new rules to make local generators participate in network stability. Consequently, national and international grid codes, which define the connection rules for stability and safety of electrical power systems, have been updated requiring distributed generators and electrical storage systems to supply stabilizing contributions. In this scenario, specific attention to the uncontrolled islanding issue has to be addressed since currently required anti-islanding protection systems, based on relays locally measuring voltage and frequency, could no longer be suitable. In this paper, the effects on the interface protection performance of different LV generators’ stabilizing functions are analysed. The study takes into account existing requirements, such as the generators’ active power regulation (according to the measured frequency and reactive power regulation (depending on the local measured voltage. In addition, the paper focuses on other stabilizing features under discussion, derived from the medium voltage (MV distribution network grid codes or proposed in the literature, such as fast voltage support (FVS and inertia emulation. Stabilizing functions have been reproduced in the DIgSILENT PowerFactory 2016 software environment, making use of its native programming language. Later, they are tested both alone and together, aiming to obtain a comprehensive analysis on their impact on the anti-islanding protection effectiveness. Through dynamic simulations in several network scenarios the paper demonstrates the detrimental impact that such stabilizing regulations may have on loss-of-main protection effectiveness, leading to an increased risk of unintentional islanding.

  12. TIGER: Turbomachinery interactive grid generation

    Science.gov (United States)

    Soni, Bharat K.; Shih, Ming-Hsin; Janus, J. Mark

    1992-01-01

    A three dimensional, interactive grid generation code, TIGER, is being developed for analysis of flows around ducted or unducted propellers. TIGER is a customized grid generator that combines new technology with methods from general grid generation codes. The code generates multiple block, structured grids around multiple blade rows with a hub and shroud for either C grid or H grid topologies. The code is intended for use with a Euler/Navier-Stokes solver also being developed, but is general enough for use with other flow solvers. TIGER features a silicon graphics interactive graphics environment that displays a pop-up window, graphics window, and text window. The geometry is read as a discrete set of points with options for several industrial standard formats and NASA standard formats. Various splines are available for defining the surface geometries. Grid generation is done either interactively or through a batch mode operation using history files from a previously generated grid. The batch mode operation can be done either with a graphical display of the interactive session or with no graphics so that the code can be run on another computer system. Run time can be significantly reduced by running on a Cray-YMP.

  13. Discrete Adjoint-Based Design Optimization of Unsteady Turbulent Flows on Dynamic Unstructured Grids

    Science.gov (United States)

    Nielsen, Eric J.; Diskin, Boris; Yamaleev, Nail K.

    2009-01-01

    An adjoint-based methodology for design optimization of unsteady turbulent flows on dynamic unstructured grids is described. The implementation relies on an existing unsteady three-dimensional unstructured grid solver capable of dynamic mesh simulations and discrete adjoint capabilities previously developed for steady flows. The discrete equations for the primal and adjoint systems are presented for the backward-difference family of time-integration schemes on both static and dynamic grids. The consistency of sensitivity derivatives is established via comparisons with complex-variable computations. The current work is believed to be the first verified implementation of an adjoint-based optimization methodology for the true time-dependent formulation of the Navier-Stokes equations in a practical computational code. Large-scale shape optimizations are demonstrated for turbulent flows over a tiltrotor geometry and a simulated aeroelastic motion of a fighter jet.

  14. A novel approach for UI charge reduction using AMI based load prioritization in smart grid

    Directory of Open Access Journals (Sweden)

    Avani Pujara

    2017-09-01

    Full Text Available System frequency is vital part for power system balance. As per India Electricity Grid code frequency should be in the range of 49.5 Hz–50.5 Hz. Deviation from above mentioned range is charged as Unscheduled Interchange (UI charge. This paper proposes a new method for load and frequency control based on control of third parameter of three-part Availability Based Tariff (ABT i.e. Unscheduled Interchange charges. New circuit is designed considering prioritization of load and using Advanced Metering Infrastructure (AMI under Smart Grid environment.

  15. A neutron spectrum unfolding code based on iterative procedures

    International Nuclear Information System (INIS)

    Ortiz R, J. M.; Vega C, H. R.

    2012-10-01

    In this work, the version 3.0 of the neutron spectrum unfolding code called Neutron Spectrometry and Dosimetry from Universidad Autonoma de Zacatecas (NSDUAZ), is presented. This code was designed in a graphical interface under the LabVIEW programming environment and it is based on the iterative SPUNIT iterative algorithm, using as entrance data, only the rate counts obtained with 7 Bonner spheres based on a 6 Lil(Eu) neutron detector. The main features of the code are: it is intuitive and friendly to the user; it has a programming routine which automatically selects the initial guess spectrum by using a set of neutron spectra compiled by the International Atomic Energy Agency. Besides the neutron spectrum, this code calculates the total flux, the mean energy, H(10), h(10), 15 dosimetric quantities for radiation protection porpoises and 7 survey meter responses, in four energy grids, based on the International Atomic Energy Agency compilation. This code generates a full report in html format with all relevant information. In this work, the neutron spectrum of a 241 AmBe neutron source on air, located at 150 cm from detector, is unfolded. (Author)

  16. Study of DFIG Wind Turbine Fault Ride-Through According to The Danish Grid Code

    DEFF Research Database (Denmark)

    Abulanwar, Elsayed; Chen, Zhe; Bak-Jensen, Birgitte

    2013-01-01

    of the DC link voltage and the reactive power, and counteract the DC link voltage runaway. Moreover, the GSC is dedicated to inject more reactive power during voltage dips to satisfy the grid code reactive power support obligation. A conventional PI controller is devoted to control the rotor side converter...

  17. Grid Transmission Expansion Planning Model Based on Grid Vulnerability

    Science.gov (United States)

    Tang, Quan; Wang, Xi; Li, Ting; Zhang, Quanming; Zhang, Hongli; Li, Huaqiang

    2018-03-01

    Based on grid vulnerability and uniformity theory, proposed global network structure and state vulnerability factor model used to measure different grid models. established a multi-objective power grid planning model which considering the global power network vulnerability, economy and grid security constraint. Using improved chaos crossover and mutation genetic algorithm to optimize the optimal plan. For the problem of multi-objective optimization, dimension is not uniform, the weight is not easy given. Using principal component analysis (PCA) method to comprehensive assessment of the population every generation, make the results more objective and credible assessment. the feasibility and effectiveness of the proposed model are validated by simulation results of Garver-6 bus system and Garver-18 bus.

  18. Disaster Monitoring using Grid Based Data Fusion Algorithms

    Directory of Open Access Journals (Sweden)

    Cătălin NAE

    2010-12-01

    Full Text Available This is a study of the application of Grid technology and high performance parallelcomputing to a candidate algorithm for jointly accomplishing data fusion from different sensors. Thisincludes applications for both image analysis and/or data processing for simultaneously trackingmultiple targets in real-time. The emphasis is on comparing the architectures of the serial andparallel algorithms, and characterizing the performance benefits achieved by the parallel algorithmwith both on-ground and in-space hardware implementations. The improved performance levelsachieved by the use of Grid technology (middleware for Parallel Data Fusion are presented for themain metrics of interest in near real-time applications, namely latency, total computation load, andtotal sustainable throughput. The objective of this analysis is, therefore, to demonstrate animplementation of multi-sensor data fusion and/or multi-target tracking functions within an integratedmulti-node portable HPC architecture based on emerging Grid technology. The key metrics to bedetermined in support of ongoing system analyses includes: required computational throughput inMFLOPS; latency between receipt of input data and resulting outputs; and scalability, processorutilization and memory requirements. Furthermore, the standard MPI functions are considered to beused for inter-node communications in order to promote code portability across multiple HPCcomputer platforms, both in space and on-ground.

  19. Optimized Reactive Power Flow of DFIG Power Converters for Better Reliability Performance Considering Grid Codes

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede; Lau, Mogens

    2015-01-01

    . In order to fulfill the modern grid codes, over-excited reactive power injection will further reduce the lifetime of the rotor-side converter. In this paper, the additional stress of the power semiconductor due to the reactive power injection is firstly evaluated in terms of modulation index...

  20. Low voltage ride-through capability control for single-stage inverter-based grid-connected photovoltaic power plant

    DEFF Research Database (Denmark)

    Al-Shetwi, Ali Q.; Sujod, Muhamad Zahim; Blaabjerg, Frede

    2018-01-01

    to enhance the LVRT capability based on the Malaysian standards and modern grid codes connection requirements. The proposed control overcomes the problems of dc-link over-voltage and ac over-current that may cause disconnection or damage to the inverter. For this purpose, dc-chopper brake controller...... to improve the capability of ride-through fault safely and keep the inverter connected, but also to provide grid support through active and reactive power control at different type of faults....

  1. Grid Voltage Synchronization for Distributed Generation Systems under Grid Fault Conditions

    DEFF Research Database (Denmark)

    Luna, Alvaro; Rocabert, J.; Candela, I.

    2015-01-01

    on the installation of STATCOMs and DVRs, as well as on advanced control functionalities for the existing power converters of distributed generation plants, have contributed to enhance their response under faulty and distorted scenarios and, hence, to fulfill these requirements. In order to achieve satisfactory......The actual grid code requirements for the grid connection of distributed generation systems, mainly wind and PV systems, are becoming very demanding. The Transmission System Operators (TSOs) are especially concerned about the Low Voltage Ride Through requirements. Solutions based...

  2. Recent Developments in Grid Generation and Force Integration Technology for Overset Grids

    Science.gov (United States)

    Chan, William M.; VanDalsem, William R. (Technical Monitor)

    1994-01-01

    Recent developments in algorithms and software tools for generating overset grids for complex configurations are described. These include the overset surface grid generation code SURGRD and version 2.0 of the hyperbolic volume grid generation code HYPGEN. The SURGRD code is in beta test mode where the new features include the capability to march over a collection of panel networks, a variety of ways to control the side boundaries and the marching step sizes and distance, a more robust projection scheme and an interpolation option. New features in version 2.0 of HYPGEN include a wider range of boundary condition types. The code also allows the user to specify different marching step sizes and distance for each point on the surface grid. A scheme that takes into account of the overlapped zones on the body surface for the purpose of forces and moments computation is also briefly described, The process involves the following two software modules: MIXSUR - a composite grid generation module to produce a collection of quadrilaterals and triangles on which pressure and viscous stresses are to be integrated, and OVERINT - a forces and moments integration module.

  3. Geodynamo and mantle convection simulations on the Earth Simulator using the Yin-Yang grid

    International Nuclear Information System (INIS)

    Kageyama, Akira; Yoshida, Masaki

    2005-01-01

    We have developed finite difference codes based on the Yin-Yang grid for the geodynamo simulation and the mantle convection simulation. The Yin-Yang grid is a kind of spherical overset grid that is composed of two identical component grids. The intrinsic simplicity of the mesh configuration of the Yin-Yang grid enables us to develop highly optimized simulation codes on massively parallel supercomputers. The Yin-Yang geodynamo code has achieved 15.2 Tflops with 4096 processors on the Earth Simulator. This represents 46% of the theoretical peak performance. The Yin-Yang mantle code has enabled us to carry out mantle convection simulations in realistic regimes with a Rayleigh number of 10 7 including strongly temperature dependent viscosity with spatial contrast up to 10 6

  4. GAMERA - The New Magnetospheric Code

    Science.gov (United States)

    Lyon, J.; Sorathia, K.; Zhang, B.; Merkin, V. G.; Wiltberger, M. J.; Daldorff, L. K. S.

    2017-12-01

    The Lyon-Fedder-Mobarry (LFM) code has been a main-line magnetospheric simulation code for 30 years. The code base, designed in the age of memory to memory vector ma- chines,is still in wide use for science production but needs upgrading to ensure the long term sustainability. In this presentation, we will discuss our recent efforts to update and improve that code base and also highlight some recent results. The new project GAM- ERA, Grid Agnostic MHD for Extended Research Applications, has kept the original design characteristics of the LFM and made significant improvements. The original de- sign included high order numerical differencing with very aggressive limiting, the ability to use arbitrary, but logically rectangular, grids, and maintenance of div B = 0 through the use of the Yee grid. Significant improvements include high-order upwinding and a non-clipping limiter. One other improvement with wider applicability is an im- proved averaging technique for the singularities in polar and spherical grids. The new code adopts a hybrid structure - multi-threaded OpenMP with an overarching MPI layer for large scale and coupled applications. The MPI layer uses a combination of standard MPI and the Global Array Toolkit from PNL to provide a lightweight mechanism for coupling codes together concurrently. The single processor code is highly efficient and can run magnetospheric simulations at the default CCMC resolution faster than real time on a MacBook pro. We have run the new code through the Athena suite of tests, and the results compare favorably with the codes available to the astrophysics community. LFM/GAMERA has been applied to many different situations ranging from the inner and outer heliosphere and magnetospheres of Venus, the Earth, Jupiter and Saturn. We present example results the Earth's magnetosphere including a coupled ring current (RCM), the magnetospheres of Jupiter and Saturn, and the inner heliosphere.

  5. Further validation of liquid metal MHD code for unstructured grid based on OpenFOAM

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Jingchao; Chen, Hongli, E-mail: hlchen1@ustc.edu.cn; He, Qingyun; Ye, Minyou

    2015-11-15

    Highlights: • Specific correction scheme has been adopted to revise the calculating result for non-orthogonal meshes. • The developed MHD code based on OpenFOAM platform has been validated by benchmark cases under uniform and non-uniform magnetic field in round and rectangular ducts. • ALEX experimental results have been used to validate the MHD code based on OpenFOAM. - Abstract: In fusion liquid metal blankets, complex geometries involving contractions, expansions, bends, manifolds are very common. The characteristics of liquid metal flow in these geometries are significant. In order to extend the magnetohydrodynamic (MHD) solver developed on OpenFOAM platform to be applied in the complex geometry, the MHD solver based on unstructured meshes has been implemented. The adoption of non-orthogonal correction techniques in the solver makes it possible to process the non-orthogonal meshes in complex geometries. The present paper focused on the validation of the code under critical conditions. An analytical solution benchmark case and two experimental benchmark cases were conducted to validate the code. Benchmark case I is MHD flow in a circular pipe with arbitrary electric conductivity of the walls in a uniform magnetic field. Benchmark cases II and III are experimental cases of 3D laminar steady MHD flow under fringing magnetic field. In all these cases, the numerical results match well with the benchmark cases.

  6. Further validation of liquid metal MHD code for unstructured grid based on OpenFOAM

    International Nuclear Information System (INIS)

    Feng, Jingchao; Chen, Hongli; He, Qingyun; Ye, Minyou

    2015-01-01

    Highlights: • Specific correction scheme has been adopted to revise the calculating result for non-orthogonal meshes. • The developed MHD code based on OpenFOAM platform has been validated by benchmark cases under uniform and non-uniform magnetic field in round and rectangular ducts. • ALEX experimental results have been used to validate the MHD code based on OpenFOAM. - Abstract: In fusion liquid metal blankets, complex geometries involving contractions, expansions, bends, manifolds are very common. The characteristics of liquid metal flow in these geometries are significant. In order to extend the magnetohydrodynamic (MHD) solver developed on OpenFOAM platform to be applied in the complex geometry, the MHD solver based on unstructured meshes has been implemented. The adoption of non-orthogonal correction techniques in the solver makes it possible to process the non-orthogonal meshes in complex geometries. The present paper focused on the validation of the code under critical conditions. An analytical solution benchmark case and two experimental benchmark cases were conducted to validate the code. Benchmark case I is MHD flow in a circular pipe with arbitrary electric conductivity of the walls in a uniform magnetic field. Benchmark cases II and III are experimental cases of 3D laminar steady MHD flow under fringing magnetic field. In all these cases, the numerical results match well with the benchmark cases.

  7. Real-space grids and the Octopus code as tools for the development of new simulation approaches for electronic systems

    Science.gov (United States)

    Andrade, Xavier; Strubbe, David; De Giovannini, Umberto; Larsen, Ask Hjorth; Oliveira, Micael J. T.; Alberdi-Rodriguez, Joseba; Varas, Alejandro; Theophilou, Iris; Helbig, Nicole; Verstraete, Matthieu J.; Stella, Lorenzo; Nogueira, Fernando; Aspuru-Guzik, Alán; Castro, Alberto; Marques, Miguel A. L.; Rubio, Angel

    Real-space grids are a powerful alternative for the simulation of electronic systems. One of the main advantages of the approach is the flexibility and simplicity of working directly in real space where the different fields are discretized on a grid, combined with competitive numerical performance and great potential for parallelization. These properties constitute a great advantage at the time of implementing and testing new physical models. Based on our experience with the Octopus code, in this article we discuss how the real-space approach has allowed for the recent development of new ideas for the simulation of electronic systems. Among these applications are approaches to calculate response properties, modeling of photoemission, optimal control of quantum systems, simulation of plasmonic systems, and the exact solution of the Schr\\"odinger equation for low-dimensionality systems.

  8. An overset grid approach to linear wave-structure interaction

    DEFF Research Database (Denmark)

    Read, Robert; Bingham, Harry B.

    2012-01-01

    A finite-difference based approach to wave-structure interaction is reported that employs the overset approach to grid generation. A two-dimensional code that utilizes the Overture C++ library has been developed to solve the linear radiation problem for a floating body of arbitrary form. This sof......A finite-difference based approach to wave-structure interaction is reported that employs the overset approach to grid generation. A two-dimensional code that utilizes the Overture C++ library has been developed to solve the linear radiation problem for a floating body of arbitrary form...

  9. MrGrid: a portable grid based molecular replacement pipeline.

    Directory of Open Access Journals (Sweden)

    Jason W Schmidberger

    Full Text Available BACKGROUND: The crystallographic determination of protein structures can be computationally demanding and for difficult cases can benefit from user-friendly interfaces to high-performance computing resources. Molecular replacement (MR is a popular protein crystallographic technique that exploits the structural similarity between proteins that share some sequence similarity. But the need to trial permutations of search models, space group symmetries and other parameters makes MR time- and labour-intensive. However, MR calculations are embarrassingly parallel and thus ideally suited to distributed computing. In order to address this problem we have developed MrGrid, web-based software that allows multiple MR calculations to be executed across a grid of networked computers, allowing high-throughput MR. METHODOLOGY/PRINCIPAL FINDINGS: MrGrid is a portable web based application written in Java/JSP and Ruby, and taking advantage of Apple Xgrid technology. Designed to interface with a user defined Xgrid resource the package manages the distribution of multiple MR runs to the available nodes on the Xgrid. We evaluated MrGrid using 10 different protein test cases on a network of 13 computers, and achieved an average speed up factor of 5.69. CONCLUSIONS: MrGrid enables the user to retrieve and manage the results of tens to hundreds of MR calculations quickly and via a single web interface, as well as broadening the range of strategies that can be attempted. This high-throughput approach allows parameter sweeps to be performed in parallel, improving the chances of MR success.

  10. Coupling an analytical description of anti-scatter grids with simulation software of radiographic systems using Monte Carlo code; Couplage d'une methode de description analytique de grilles anti diffusantes avec un logiciel de simulation de systemes radiographiques base sur un code Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Rinkel, J.; Dinten, J.M.; Tabary, J

    2004-07-01

    The use of focused anti-scatter grids on digital radiographic systems with two-dimensional detectors produces acquisitions with a decreased scatter to primary ratio and thus improved contrast and resolution. Simulation software is of great interest in optimizing grid configuration according to a specific application. Classical simulators are based on complete detailed geometric descriptions of the grid. They are accurate but very time consuming since they use Monte Carlo code to simulate scatter within the high-frequency grids. We propose a new practical method which couples an analytical simulation of the grid interaction with a radiographic system simulation program. First, a two dimensional matrix of probability depending on the grid is created offline, in which the first dimension represents the angle of impact with respect to the normal to the grid lines and the other the energy of the photon. This matrix of probability is then used by the Monte Carlo simulation software in order to provide the final scattered flux image. To evaluate the gain of CPU time, we define the increasing factor as the increase of CPU time of the simulation with as opposed to without the grid. Increasing factors were calculated with the new model and with classical methods representing the grid with its CAD model as part of the object. With the new method, increasing factors are shorter by one to two orders of magnitude compared with the second one. These results were obtained with a difference in calculated scatter of less than five percent between the new and the classical method. (authors)

  11. Doubly fed induction generator based wind turbine systems subject to recurring grid faults

    DEFF Research Database (Denmark)

    Chen, Wenjie; Blaabjerg, Frede; Zhu, Nan

    2014-01-01

    New grid codes demand the wind turbine systems to ride through recurring grid faults. In this paper, the performance of the Doubly Fed Induction Generator wind turbine system under recurring grid faults is analyzed. The stator natural flux produced by the voltage recovery after the first grid fault...... may be superposed on the stator natural flux produced by the second grid fault, and it may result in large current and voltage transient. The damping of the stator natural flux can be accelerated with a rotor natural current in its opposite direction after voltage recovery, but larger torque....... The performance of DFIG under recurring grid faults is verified by the simulation and experiments....

  12. An Agent-Based Model for Zip-Code Level Diffusion of Electric Vehicles and Electricity Consumption in New York City

    Directory of Open Access Journals (Sweden)

    Azadeh Ahkamiraad

    2018-03-01

    Full Text Available Current power grids in many countries are not fully prepared for high electric vehicle (EV penetration, and there is evidence that the construction of additional grid capacity is constantly outpaced by EV diffusion. If this situation continues, then it will compromise grid reliability and cause problems such as system overload, voltage and frequency fluctuations, and power losses. This is especially true for densely populated areas where the grid capacity is already strained with existing old infrastructure. The objective of this research is to identify the zip-code level electricity consumption that is associated with large-scale EV adoption in New York City, one of the most densely populated areas in the United States (U.S.. We fuse the Fisher and Pry diffusion model and Rogers model within the agent-based simulation to forecast zip-code level EV diffusion and the required energy capacity to satisfy the charging demand. The research outcomes will assist policy makers and grid operators in making better planning decisions on the locations and timing of investments during the transition to smarter grids and greener transportation.

  13. Ecosystem Based Business Model of Smart Grid

    OpenAIRE

    Lundgaard, Morten Raahauge; Ma, Zheng; Jørgensen, Bo Nørregaard

    2015-01-01

    This paper tries to investigate the ecosystem based business model in a smart grid infrastructure and the potential of value capture in the highly complex macro infrastructure such as smart grid. This paper proposes an alternative perspective to study the smart grid business ecosystem to support the infrastructural challenges, such as the interoperability of business components for smart grid. So far little research has explored the business ecosystem in the smart grid concept. The study on t...

  14. SCALEA-G: A Unified Monitoring and Performance Analysis System for the Grid

    Directory of Open Access Journals (Sweden)

    Hong-Linh Truong

    2004-01-01

    Full Text Available This paper describes SCALEA-G, a unified monitoring and performance analysis system for the Grid. SCALEA-G is implemented as a set of grid services based on the Open Grid Services Architecture (OGSA. SCALEA-G provides an infrastructure for conducting online monitoring and performance analysis of a variety of Grid services including computational and network resources, and Grid applications. Both push and pull models are supported, providing flexible and scalable monitoring and performance analysis. Source code and dynamic instrumentation are implemented to perform profiling and monitoring of Grid applications. A novel instrumentation request language for dynamic instrumentation and a standardized intermediate representation for binary code have been developed to facilitate the interaction between client and instrumentation services.

  15. Developing Information Power Grid Based Algorithms and Software

    Science.gov (United States)

    Dongarra, Jack

    1998-01-01

    This was an exploratory study to enhance our understanding of problems involved in developing large scale applications in a heterogeneous distributed environment. It is likely that the large scale applications of the future will be built by coupling specialized computational modules together. For example, efforts now exist to couple ocean and atmospheric prediction codes to simulate a more complete climate system. These two applications differ in many respects. They have different grids, the data is in different unit systems and the algorithms for inte,-rating in time are different. In addition the code for each application is likely to have been developed on different architectures and tend to have poor performance when run on an architecture for which the code was not designed, if it runs at all. Architectural differences may also induce differences in data representation which effect precision and convergence criteria as well as data transfer issues. In order to couple such dissimilar codes some form of translation must be present. This translation should be able to handle interpolation from one grid to another as well as construction of the correct data field in the correct units from available data. Even if a code is to be developed from scratch, a modular approach will likely be followed in that standard scientific packages will be used to do the more mundane tasks such as linear algebra or Fourier transform operations. This approach allows the developers to concentrate on their science rather than becoming experts in linear algebra or signal processing. Problems associated with this development approach include difficulties associated with data extraction and translation from one module to another, module performance on different nodal architectures, and others. In addition to these data and software issues there exists operational issues such as platform stability and resource management.

  16. A Grid Voltage Measurement Method for Wind Power Systems during Grid Fault Conditions

    Directory of Open Access Journals (Sweden)

    Cheol-Hee Yoo

    2014-11-01

    Full Text Available Grid codes in many countries require low-voltage ride-through (LVRT capability to maintain power system stability and reliability during grid fault conditions. To meet the LVRT requirement, wind power systems must stay connected to the grid and also supply reactive currents to the grid to support the recovery from fault voltages. This paper presents a new fault detection method and inverter control scheme to improve the LVRT capability for full-scale permanent magnet synchronous generator (PMSG wind power systems. Fast fault detection can help the wind power systems maintain the DC-link voltage in a safe region. The proposed fault detection method is based on on-line adaptive parameter estimation. The performance of the proposed method is verified in comparison to the conventional voltage measurement method defined in the IEC 61400-21 standard.

  17. Efficient Eulerian gyrokinetic simulations with block-structured grids

    International Nuclear Information System (INIS)

    Jarema, Denis

    2017-01-01

    Gaining a deep understanding of plasma microturbulence is of paramount importance for the development of future nuclear fusion reactors, because it causes a strong outward transport of heat and particles. Gyrokinetics has proven itself as a valid mathematical model to simulate such plasma microturbulence effects. In spite of the advantages of this model, nonlinear radially extended (or global) gyrokinetic simulations are still extremely computationally expensive, involving a very large number of computational grid points. Hence, methods that reduce the number of grid points without a significant loss of accuracy are a prerequisite to be able to run high-fidelity simulations. At the level of the mathematical model, the gyrokinetic approach achieves a reduction from six to five coordinates in comparison to the fully kinetic models. This reduction leads to an important decrease in the total number of computational grid points. However, the velocity space mixed with the radial direction still requires a very fine resolution in grid based codes, due to the disparities in the thermal speed, which are caused by a strong temperature variation along the radial direction. An attempt to address this problem by modifying the underlying gyrokinetic set of equations leads to additional nonlinear terms, which are the most expensive parts to simulate. Furthermore, because of these modifications, well-established and computationally efficient implementations developed for the original set of equations can no longer be used. To tackle such issues, in this thesis we introduce an alternative approach of blockstructured grids. This approach reduces the number of grid points significantly, but without changing the underlying mathematical model. Furthermore, our technique is minimally invasive and allows the reuse of a large amount of already existing code using rectilinear grids, modifications being necessary only on the block boundaries. Moreover, the block-structured grid can be

  18. Efficient Eulerian gyrokinetic simulations with block-structured grids

    Energy Technology Data Exchange (ETDEWEB)

    Jarema, Denis

    2017-01-20

    Gaining a deep understanding of plasma microturbulence is of paramount importance for the development of future nuclear fusion reactors, because it causes a strong outward transport of heat and particles. Gyrokinetics has proven itself as a valid mathematical model to simulate such plasma microturbulence effects. In spite of the advantages of this model, nonlinear radially extended (or global) gyrokinetic simulations are still extremely computationally expensive, involving a very large number of computational grid points. Hence, methods that reduce the number of grid points without a significant loss of accuracy are a prerequisite to be able to run high-fidelity simulations. At the level of the mathematical model, the gyrokinetic approach achieves a reduction from six to five coordinates in comparison to the fully kinetic models. This reduction leads to an important decrease in the total number of computational grid points. However, the velocity space mixed with the radial direction still requires a very fine resolution in grid based codes, due to the disparities in the thermal speed, which are caused by a strong temperature variation along the radial direction. An attempt to address this problem by modifying the underlying gyrokinetic set of equations leads to additional nonlinear terms, which are the most expensive parts to simulate. Furthermore, because of these modifications, well-established and computationally efficient implementations developed for the original set of equations can no longer be used. To tackle such issues, in this thesis we introduce an alternative approach of blockstructured grids. This approach reduces the number of grid points significantly, but without changing the underlying mathematical model. Furthermore, our technique is minimally invasive and allows the reuse of a large amount of already existing code using rectilinear grids, modifications being necessary only on the block boundaries. Moreover, the block-structured grid can be

  19. Depth Measurement Based on Infrared Coded Structured Light

    Directory of Open Access Journals (Sweden)

    Tong Jia

    2014-01-01

    Full Text Available Depth measurement is a challenging problem in computer vision research. In this study, we first design a new grid pattern and develop a sequence coding and decoding algorithm to process the pattern. Second, we propose a linear fitting algorithm to derive the linear relationship between the object depth and pixel shift. Third, we obtain depth information on an object based on this linear relationship. Moreover, 3D reconstruction is implemented based on Delaunay triangulation algorithm. Finally, we utilize the regularity of the error curves to correct the system errors and improve the measurement accuracy. The experimental results show that the accuracy of depth measurement is related to the step length of moving object.

  20. Modeling and Grid impedance Variation Analysis of Parallel Connected Grid Connected Inverter based on Impedance Based Harmonic Analysis

    DEFF Research Database (Denmark)

    Kwon, JunBum; Wang, Xiongfei; Bak, Claus Leth

    2014-01-01

    This paper addresses the harmonic compensation error problem existing with parallel connected inverter in the same grid interface conditions by means of impedance-based analysis and modeling. Unlike the single grid connected inverter, it is found that multiple parallel connected inverters and grid...... impedance can make influence to each other if they each have a harmonic compensation function. The analysis method proposed in this paper is based on the relationship between the overall output impedance and input impedance of parallel connected inverter, where controller gain design method, which can...

  1. Ecosystem Based Business Model of Smart Grid

    DEFF Research Database (Denmark)

    Lundgaard, Morten Raahauge; Ma, Zheng; Jørgensen, Bo Nørregaard

    2015-01-01

    This paper tries to investigate the ecosystem based business model in a smart grid infrastructure and the potential of value capture in the highly complex macro infrastructure such as smart grid. This paper proposes an alternative perspective to study the smart grid business ecosystem to support...... the infrastructural challenges, such as the interoperability of business components for smart grid. So far little research has explored the business ecosystem in the smart grid concept. The study on the smart grid with the theory of business ecosystem may open opportunities to understand market catalysts. This study...... contributes an understanding of business ecosystem applicable for smart grid. Smart grid infrastructure is an intricate business ecosystem, which have several intentions to deliver the value proposition and what it should be. The findings help to identify and capture value from markets....

  2. Feature combination analysis in smart grid based using SOM for Sudan national grid

    Science.gov (United States)

    Bohari, Z. H.; Yusof, M. A. M.; Jali, M. H.; Sulaima, M. F.; Nasir, M. N. M.

    2015-12-01

    In the investigation of power grid security, the cascading failure in multicontingency situations has been a test because of its topological unpredictability and computational expense. Both system investigations and burden positioning routines have their limits. In this project, in view of sorting toward Self Organizing Maps (SOM), incorporated methodology consolidating spatial feature (distance)-based grouping with electrical attributes (load) to evaluate the vulnerability and cascading impact of various part sets in the force lattice. Utilizing the grouping result from SOM, sets of overwhelming stacked beginning victimized people to perform assault conspires and asses the consequent falling impact of their failures, and this SOM-based approach viably distinguishes the more powerless sets of substations than those from the conventional burden positioning and other bunching strategies. The robustness of power grids is a central topic in the design of the so called "smart grid". In this paper, to analyze the measures of importance of the nodes in a power grid under cascading failure. With these efforts, we can distinguish the most vulnerable nodes and protect them, improving the safety of the power grid. Also we can measure if a structure is proper for power grids.

  3. New grid-planning and certification approaches for the large-scale offshore-wind farm grid-connection systems

    Energy Technology Data Exchange (ETDEWEB)

    Heising, C.; Bartelt, R. [Avasition GmbH, Dortmund (Germany); Zadeh, M. Koochack; Lebioda, T.J.; Jung, J. [TenneT Offshore GmbH, Bayreuth (Germany)

    2012-07-01

    Stable operation of the offshore-wind farms (OWF) and stable grid connection under stationary and dynamic conditions are essential to achieve a stable public power supply. To reach this aim, adequate grid-planning and certification approaches are a major advantage. Within this paper, the fundamental characteristics of the offshore-wind farms and their grid-connection systems are given. The main goal of this research project is to study the stability of the offshore grid especially in terms of subharmonic stability for the likely future extension stage of the offshore grids i.e. having parallel connection of two or more HVDC links and for certain operating scenarios e.g. overload scenario. The current requirements according to the grid code are not the focus of this research project. The goal is to study and define potential additional grid code requirements, simulations, tests and grid planning methods for the future. (orig.)

  4. Context-Aware Usage-Based Grid Authorization Framework

    Institute of Scientific and Technical Information of China (English)

    CUI Yongquan; HONG Fan; FU Cai

    2006-01-01

    Due to inherent heterogeneity, multi-domain characteristic and highly dynamic nature, authorization is a critical concern in grid computing. This paper proposes a general authorization and access control architecture, grid usage control (GUCON), for grid computing. It's based on the next generation access control mechanism usage control (UCON) model. The GUCON Framework dynamic grants and adapts permission to the subject based on a set of contextual information collected from the system environments; while retaining the authorization by evaluating access requests based on subject attributes, object attributes and requests. In general, GUCON model provides very flexible approaches to adapt the dynamically security request. GUCON model is being implemented in our experiment prototype.

  5. Expected Range of Cooperation Between Transmission System Operators and Distribution System Operators After Implementation of ENTSO-E Grid Codes

    Directory of Open Access Journals (Sweden)

    Tomasz Pakulski

    2015-06-01

    Full Text Available The authors present the prospects of cooperation between transmission system operators (TSO and distribution system operators (DSO after entry into force ENTSO-E (European Network of Transmission System Operators for Electricity grid codes. New areas of DSO activities, associated with offering TSO aggregated services for national power system regulation based on the regulation resources connected to the distribution grid, and services on the distribution system level as part of the creation of local balancing areas (LBA are presented. The paper also presents the possibilities of providing ancillary services by different types of distributed generation sources in the distribution network. The LBA concept, which involves integrated management of local regulation resources including generation, demand, and energy storage is described. The options of the renewable energy sources (RES using for voltage and reactive power control in the distribution network with the use of wind farms (WF connected to the distribution system are characterized.

  6. Grid Integration of PV Power based on PHIL testing using different Interface Algorithms

    DEFF Research Database (Denmark)

    Craciun, Bogdan-Ionut; Kerekes, Tamas; Sera, Dezso

    2013-01-01

    to be more active in grid support. Therefore, a better understanding and detailed analysis of the PV systems interaction with the grid is needed; hence power hardware in the loop (PHIL) testing involving PV power became an interesting subject to look into. To test PV systems for grid code (GC) compliance......Photovoltaic (PV) power among all renewable energies had the most accelerated growth rate in terms of installed capacity in recent years. Transmission System Operators (TSOs) changed their perspective about PV power and started to include it into their planning and operation, imposing PV systems...

  7. APORT: a program for the area-based apportionment of county variables to cells of a polar grid. [Airborne pollutant transport models

    Energy Technology Data Exchange (ETDEWEB)

    Fields, D.E.; Little, C.A.

    1978-11-01

    The APORT computer code was developed to apportion variables tabulated for polygon-structured civil districts onto cells of a polar grid. The apportionment is based on fractional overlap between the polygon and the grid cells. Centering the origin of the polar system at a pollutant source site yields results that are very useful for assessing and interpreting the effects of airborne pollutant dissemination. The APOPLT graphics code, which uses the same data set as APORT, provides a convenient visual display of the polygon structure and the extent of the polar grid. The APORT/APOPLT methodology was verified by application to county summaries of cattle population for counties surrounding the Oyster Creek, New Jersey, nuclear power plant. These numerical results, which were obtained using approximately 2-min computer time on an IBM System 360/91 computer, compare favorably to results of manual computations in both speed and accuracy.

  8. Compact Hilbert Curve Index Algorithm Based on Gray Code

    Directory of Open Access Journals (Sweden)

    CAO Xuefeng

    2016-12-01

    Full Text Available Hilbert curve has best clustering in various kinds of space filling curves, and has been used as an important tools in discrete global grid spatial index design field. But there are lots of redundancies in the standard Hilbert curve index when the data set has large differences between dimensions. In this paper, the construction features of Hilbert curve is analyzed based on Gray code, and then the compact Hilbert curve index algorithm is put forward, in which the redundancy problem has been avoided while Hilbert curve clustering preserved. Finally, experiment results shows that the compact Hilbert curve index outperforms the standard Hilbert index, their 1 computational complexity is nearly equivalent, but the real data set test shows the coding time and storage space decrease 40%, the speedup ratio of sorting speed is nearly 4.3.

  9. Fulfilment of Grid Code Obligations by Large Offshore Wind Farms Clusters Connected via HVDC Corridors

    OpenAIRE

    Attya, A.B.; Anaya-Lara, Olimpo; Ledesma, P.; Svendsen, Harald Georg

    2016-01-01

    - The foreseen high penetration levels of wind power will force the systems operators to apply restrictive constraints on wind power plants. The ability of offshore wind clusters, which are connected via HVDC, to fulfill the grid codes, especially those related to voltage stability is investigated. This came in the frame of a project to develop an integrated and practical tool to design offshore wind clusters (EERA-DTOC). The applied case studies examine the system stability during and aft...

  10. GENECODIS-Grid: An online grid-based tool to predict functional information in gene lists

    International Nuclear Information System (INIS)

    Nogales, R.; Mejia, E.; Vicente, C.; Montes, E.; Delgado, A.; Perez Griffo, F. J.; Tirado, F.; Pascual-Montano, A.

    2007-01-01

    In this work we introduce GeneCodis-Grid, a grid-based alternative to a bioinformatics tool named Genecodis that integrates different sources of biological information to search for biological features (annotations) that frequently co-occur in a set of genes and rank them by statistical significance. GeneCodis-Grid is a web-based application that takes advantage of two independent grid networks and a computer cluster managed by a meta-scheduler and a web server that host the application. The mining of concurrent biological annotations provides significant information for the functional analysis of gene list obtained by high throughput experiments in biology. Due to the large popularity of this tool, that has registered more than 13000 visits since its publication in January 2007, there is a strong need to facilitate users from different sites to access the system simultaneously. In addition, the complexity of some of the statistical tests used in this approach has made this technique a good candidate for its implementation in a Grid opportunistic environment. (Author)

  11. A Grid Voltage Measurement Method for Wind Power Systems during Grid Fault Conditions

    OpenAIRE

    Yoo, Cheol-Hee; Chung, Il-Yop; Yoo, Hyun-Jae; Hong, Sung-Soo

    2014-01-01

    Grid codes in many countries require low-voltage ride-through (LVRT) capability to maintain power system stability and reliability during grid fault conditions. To meet the LVRT requirement, wind power systems must stay connected to the grid and also supply reactive currents to the grid to support the recovery from fault voltages. This paper presents a new fault detection method and inverter control scheme to improve the LVRT capability for full-scale permanent magnet synchronous generator (P...

  12. Aspects of a generic photovoltaic model examined under the German grid code for medium voltage

    Energy Technology Data Exchange (ETDEWEB)

    Theologitis, Ioannis-Thomas; Troester, Eckehard; Ackermann, Thomas [Energynautics GmbH, Langen (Germany)

    2011-07-01

    The increasing peneration of photovoltaic power systems into the power grid has attached attention to the issue of ensuring the smooth absorbance of the solar energy, while securing the normal and steady operation of the grid as well. Nowadays, the PV systems must meet a number of technical requirements to address this issue. This paper investigates a generic grid-connected photovoltaic model that was developed by DIgSILENT and is part of the library in the new version of PowerFactory v.14.1 software that is used in this study. The model has a nominal rated peak power of 0.5 MVA and a designed power factor cos{phi}0.95. The study focuses on the description of the model, its control system and its ability to reflect important requirements that a grid-connected PV system should have by January 2011 according to the German grid code for medium voltage. The model undergoes various simulations. Static voltage support, active power control and dynamic voltage support - Fault Ride Through (FRT) is examined. The results show that the generic model is capable for active power reduction under over-frequency occasions and FRT behavior in cases of voltage dips. The reactive power control that is added in the model improves the control system and makes the model capable for static voltage support in sudden active power injection changes at the point of common coupling. Beside the simplifications and shortcomings of this generic model, basic requirements of the modern PV systems can be addressed. Further improvements could make it more complete and applicable for more detailed studies. (orig.)

  13. Adaptive Micro-Grid Operation Based on IEC 61850

    Directory of Open Access Journals (Sweden)

    Wei Deng

    2015-05-01

    Full Text Available Automatically identifying the new equipment after its integration and adjusting operation strategy to realize “plug and play” functionality are becoming essential for micro-grid operations. In order to improve and perfect the micro-grid “plug and play” function with the increased amount of equipment with different information protocols and more diverse system applications, this paper presents a solution for adaptive micro-grid operation based on IEC 61850, and proposes the design and specific implementation methods of micro-grid “plug and play” function and system operation mode conversion in detail, by using the established IEC 61850 information model of a micro-grid. Actual operation tests based on the developed IED and micro-grid test platform are performed to verify the feasibility and validity of the proposed solution. The tests results show that the solution can automatically identify the IEC 61850 information model of equipment after its integration, intelligently adjust the operation strategies to adapt to new system states and achieves a reliable system operation mode conversion.

  14. Development of 3D CFD code based on structured non-orthogonal grids

    International Nuclear Information System (INIS)

    Vaidya, Abhijeet Mohan; Maheshwari, Naresh Kumar; Rama Rao, A.

    2016-01-01

    Most of the nuclear industry problems involve complex geometries. Solution of flow and heat transfer over complex geometries is a very important requirement for designing new reactor systems. Hence development of a general purpose three dimensional (3D) CFD code is undertaken. For handling complex shape of computational domain, implementation on structured non-orthogonal coordinates is being done. The code is validated by comparing its results for 3D inclined lid driven cavity at different inclination angles and Reynolds numbers with OpenFOAM results. This paper contains formulation and validation of the new code developed. (author)

  15. Verification of the three-dimensional tetrahedral grid SN code THOR

    International Nuclear Information System (INIS)

    Schunert, S.; Ferrer, R.; Azmy, Y.

    2013-01-01

    In this work current capabilities implemented in the novel, arbitrary-order, tetrahedral-grid short characteristics S N radiation transport code THOR are verified based on four benchmark problems: (1) A one-group Method of Manufactured Solution (MMS) problem on a cuboidal domain, (2) an infinite medium eigenvalue problem with up-scattering, (3) a homogeneous torus and (4) a bare cube eigenvalue problem with anisotropic scattering up to order three. The first benchmark problem exercises the various spatial discretization options available in THOR: The short characteristics method in conjunction with polynomial expansions of the source and face fluxes either using the complete or Lagrange family of arbitrary orders. Using the numerical solution's order of convergence test in the framework of a mesh refinement study, correct implementation of a selection of spatial expansion orders is demonstrated for two meshes with tetrahedral aspect ratios close to unity and 50. The second benchmark problem exercises the implementation of angular fluxes on reflective boundary faces that are implicit within a mesh sweep, and up-scattering. The third benchmark problem comprises cyclic dependencies within the mesh sweep thus exercising the algorithm devised for 'breaking' the cyclic dependencies. Finally, the fourth benchmark problem, a simple bare cube, is used to test correct implementation of the anisotropic scattering capability. For all test problems THOR obtains solutions that converge to the reference/exact solution with the expected rate thereby contributing to our confidence in the correctness of its tested features in the present implementation. (authors)

  16. XGC developments for a more efficient XGC-GENE code coupling

    Science.gov (United States)

    Dominski, Julien; Hager, Robert; Ku, Seung-Hoe; Chang, Cs

    2017-10-01

    In the Exascale Computing Program, the High-Fidelity Whole Device Modeling project initially aims at delivering a tightly-coupled simulation of plasma neoclassical and turbulence dynamics from the core to the edge of the tokamak. To permit such simulations, the gyrokinetic codes GENE and XGC will be coupled together. Numerical efforts are made to improve the numerical schemes agreement in the coupling region. One of the difficulties of coupling those codes together is the incompatibility of their grids. GENE is a continuum grid-based code and XGC is a Particle-In-Cell code using unstructured triangular mesh. A field-aligned filter is thus implemented in XGC. Even if XGC originally had an approximately field-following mesh, this field-aligned filter permits to have a perturbation discretization closer to the one solved in the field-aligned code GENE. Additionally, new XGC gyro-averaging matrices are implemented on a velocity grid adapted to the plasma properties, thus ensuring same accuracy from the core to the edge regions.

  17. Simulation of single grid-based phase-contrast x-ray imaging (g-PCXI)

    Energy Technology Data Exchange (ETDEWEB)

    Lim, H.W.; Lee, H.W. [Department of Radiation Convergence Engineering, iTOMO Group, Yonsei University, 1 Yonseidae-gil, Wonju, Gangwon-do 26493 (Korea, Republic of); Cho, H.S., E-mail: hscho1@yonsei.ac.kr [Department of Radiation Convergence Engineering, iTOMO Group, Yonsei University, 1 Yonseidae-gil, Wonju, Gangwon-do 26493 (Korea, Republic of); Je, U.K.; Park, C.K.; Kim, K.S.; Kim, G.A.; Park, S.Y.; Lee, D.Y.; Park, Y.O.; Woo, T.H. [Department of Radiation Convergence Engineering, iTOMO Group, Yonsei University, 1 Yonseidae-gil, Wonju, Gangwon-do 26493 (Korea, Republic of); Lee, S.H.; Chung, W.H.; Kim, J.W.; Kim, J.G. [R& D Center, JPI Healthcare Co., Ltd., Ansan 425-833 (Korea, Republic of)

    2017-04-01

    Single grid-based phase-contrast x-ray imaging (g-PCXI) technique, which was recently proposed by Wen et al. to retrieve absorption, scattering, and phase-gradient images from the raw image of the examined object, seems a practical method for phase-contrast imaging with great simplicity and minimal requirements on the setup alignment. In this work, we developed a useful simulation platform for g-PCXI and performed a simulation to demonstrate its viability. We also established a table-top setup for g-PCXI which consists of a focused-linear grid (200-lines/in strip density), an x-ray tube (100-μm focal spot size), and a flat-panel detector (48-μm pixel size) and performed a preliminary experiment with some samples to show the performance of the simulation platform. We successfully obtained phase-contrast x-ray images of much enhanced contrast from both the simulation and experiment and the simulated contract seemed similar to the experimental contrast, which shows the performance of the developed simulation platform. We expect that the simulation platform will be useful for designing an optimal g-PCXI system. - Highlights: • It is proposed for the single grid-based phase-contrast x-ray imaging (g-PCXI) technique. • We implemented for a numerical simulation code. • The preliminary experiment with several samples to compare is performed. • It is expected to be useful to design an optimal g-PCXI system.

  18. GENIE - Generation of computational geometry-grids for internal-external flow configurations

    Science.gov (United States)

    Soni, B. K.

    1988-01-01

    Progress realized in the development of a master geometry-grid generation code GENIE is presented. The grid refinement process is enhanced by developing strategies to utilize bezier curves/surfaces and splines along with weighted transfinite interpolation technique and by formulating new forcing function for the elliptic solver based on the minimization of a non-orthogonality functional. A two step grid adaptation procedure is developed by optimally blending adaptive weightings with weighted transfinite interpolation technique. Examples of 2D-3D grids are provided to illustrate the success of these methods.

  19. Numerical Analysis for IFM Grid Effect on 5x5 Rods Bundle

    International Nuclear Information System (INIS)

    Kim, Seong Jin; Cha, Jeong Hun; Seo, Kyong Won; Kim, Tae Woo; Kwon, Hyuk; Hwang, Dae Hyun

    2011-01-01

    Generally, the fuel assembly consists of fuel rods, bottom and top grids, spacer grids, mixing vane, etc. The mixing vane with spacer grid is used to increase the thermal mixing between subchannels and to increase CHF(Critical Heat Flux). IFM(Intermediate Flow Mixer) grids are used to induce lateral flow between adjacent channels and are well-known as improving CHF, also. A numerical analysis using CFD code(ANSYS CFX, version 12.1) and subchannel code(MATRA-S) was conducted to investigate the influence of IFM grid on the subchannel temperature in 5x5 rods bundle with and without the IFM grid, thermohydraulically. In this study, the quantitative improvement of the mixing effect of the IFM grid is presented from the results of CFX and MATRA-S code. Moreover, capacity of predicting subchannel temperature of MATRA-S code is compared with CFX result

  20. DIGRD: an interactive grid generating program

    International Nuclear Information System (INIS)

    Foote, H.P.; Rice, W.A.; Kincaid, C.T.

    1982-11-01

    Pacific Northwest Laboratory has completed the development and documentation of an interactive grid generating program (DIGRD, digitize grid). This program is designed to rapidly generate or modify grids necessary for the unsaturated flow code TRUST. In addition to the code, a user's manual was prepared. Unfortunately, the computer hardware that comprises the PNL interactive graphics capability is unique. Direct technology transfer is not possible, therefore, this report is intended to convey the utility of interactive graphics in supplying a grid generating capability. DIGRD has already been effectively used in the preparation of grids for the analysis of leachate movement from uranium mill tailings. The principal conclusion is that the interactive graphics employed in DIGRD are useful and economical in the development of complex grids. Grid generation activities that previously took between a half- and a full-man month can now be completed in less than a week. DIGRD users have recommended development of an uniform grid of either rectangles or equilateral triangles, which could be superimposed on any domain and then adjusted through the DIGRD program to match the boundaries of a tailings disposal facility. This improvement to the DIGRD package could further reduce the effort in grid generation while providing more optimal grids

  1. PSG: Peer-to-Peer semantic grid framework architecture

    Directory of Open Access Journals (Sweden)

    Amira Soliman

    2011-07-01

    Full Text Available The grid vision, of sharing diverse resources in a flexible, coordinated and secure manner, strongly depends on metadata. Currently, grid metadata is generated and used in an ad-hoc fashion, much of it buried in the grid middleware code libraries and database schemas. This ad-hoc expression and use of metadata causes chronic dependency on human intervention during the operation of grid machinery. Therefore, the Semantic Grid is emerged as an extension of the grid in which rich resource metadata is exposed and handled explicitly, and shared and managed via grid protocols. The layering of an explicit semantic infrastructure over the grid infrastructure potentially leads to increase interoperability and flexibility. In this paper, we present PSG framework architecture that offers semantic-based grid services. PSG architecture allows the explicit use of semantics and defining the associated grid services. PSG architecture is originated from the integration of Peer-to-Peer (P2P computing with semantics and agents. Ontologies are used in annotating each grid component, developing users/nodes profiles and organizing framework agents. While, P2P is responsible for organizing and coordinating the grid nodes and resources.

  2. ONIX results: Comparison of grid geometry (BATMAN - ELISE - flat grid)

    Science.gov (United States)

    Revel, Adrien; Mochalskyy, Serhiy; Wünderlich, Dirk; Fantz, Ursel; Minea, Tiberiu

    2017-08-01

    The 3D PIC-MCC code ONIX is dedicated to the modelling of negative hydrogen or deuterium ion extraction and the co-extracted electrons from the plasma in radio-frequency driven sources. The extraction process highly depends on the plasma characteristics close to the plasma grid where it is difficult to obtain experimental data. ONIX brings valuable insights on the plasma behavior in this area. In the code, the numerical treatment of the boundaries have been improved in order to describe with more accuracy the potential and the electric field in this vicinity. The computation time has been reduced by a factor of 2 and the parallelization efficiency has been highly improved. The influence of the magnetic field in BATMAN on the plasma behaviour has been investigated by comparing two different configurations of the magnet bars producing the filter field (internal magnets: x = 3 cm; external magnets: x = 9 cm). A flat grid geometry for the PG instead of the usual conical grid geometry has been studied to evaluate its impact on the extracted current, especially for the negative ions emitted from the surface of the PG. Finally, the ONIX code has been used for the first 3D PIC calculations ever performed for the ELISE experiment.

  3. Overview of Recent Grid Codes for PV Power Integration

    DEFF Research Database (Denmark)

    Craciun, Bogdan-Ionut; Kerekes, Tamas; Sera, Dezso

    2012-01-01

    The challenge to bring down the cost of produced photovoltaic (PV) power had a major impact on the PV market and in consequence the grid operators experienced higher and higher PV power penetration. The growing share of this decentralized generation plants started to affect the grid stability...

  4. Development of a potential based code for MHD analysis of LLCB TBM

    International Nuclear Information System (INIS)

    Bhuyan, P.J.; Goswami, K.S.

    2010-01-01

    A two dimensional solver is developed for MHD flows with low magnetic Reynolds' number based on the electrostatic potential formulation for the Lorentz forces and current densities which will be used to calculate the MHD pressure drop inside the channels of liquid breeder based Test Blanket Modules (TBMs). The flow geometry is assumed to be rectangular and perpendicular to the flow direction, with flow and electrostatic potential variations along the flow direction neglected. A structured, non-uniform, collocated grid is used in the calculation, where the velocity (u), pressure (p) and electrostatic potential (φ) are calculated at the cell centers, whereas the current densities are calculated at the cell faces. Special relaxation techniques are employed in calculating the electrostatic potential for ensuring the divergence-free condition for current density. The code is benchmarked over a square channel for various Hartmann numbers up to 25,000 with and without insulation coatings by (i) comparing the pressure drop with the approximate analytical results found in literature and (ii) comparing the pressure drop with the ones obtained in our previous calculations based on the induction formulation for the electromagnetic part. Finally the code is used to determine the MHD pressure drop in case of LLCB TBM. The code gives similar results as obtained by us in our previous calculations based on the induction formulation. However, the convergence is much faster in case of potential based code.

  5. A Structured Grid Based Solution-Adaptive Technique for Complex Separated Flows

    Science.gov (United States)

    Thornburg, Hugh; Soni, Bharat K.; Kishore, Boyalakuntla; Yu, Robert

    1996-01-01

    The objective of this work was to enhance the predictive capability of widely used computational fluid dynamic (CFD) codes through the use of solution adaptive gridding. Most problems of engineering interest involve multi-block grids and widely disparate length scales. Hence, it is desirable that the adaptive grid feature detection algorithm be developed to recognize flow structures of different type as well as differing intensity, and adequately address scaling and normalization across blocks. In order to study the accuracy and efficiency improvements due to the grid adaptation, it is necessary to quantify grid size and distribution requirements as well as computational times of non-adapted solutions. Flow fields about launch vehicles of practical interest often involve supersonic freestream conditions at angle of attack exhibiting large scale separate vortical flow, vortex-vortex and vortex-surface interactions, separated shear layers and multiple shocks of different intensity. In this work, a weight function and an associated mesh redistribution procedure is presented which detects and resolves these features without user intervention. Particular emphasis has been placed upon accurate resolution of expansion regions and boundary layers. Flow past a wedge at Mach=2.0 is used to illustrate the enhanced detection capabilities of this newly developed weight function.

  6. Reliability-Based Code Calibration

    DEFF Research Database (Denmark)

    Faber, M.H.; Sørensen, John Dalsgaard

    2003-01-01

    The present paper addresses fundamental concepts of reliability based code calibration. First basic principles of structural reliability theory are introduced and it is shown how the results of FORM based reliability analysis may be related to partial safety factors and characteristic values....... Thereafter the code calibration problem is presented in its principal decision theoretical form and it is discussed how acceptable levels of failure probability (or target reliabilities) may be established. Furthermore suggested values for acceptable annual failure probabilities are given for ultimate...... and serviceability limit states. Finally the paper describes the Joint Committee on Structural Safety (JCSS) recommended procedure - CodeCal - for the practical implementation of reliability based code calibration of LRFD based design codes....

  7. Reliability and Energy Loss in Full-scale Wind Power Converter Considering Grid Codes and Wind Classes

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede; Franke, Toke

    2014-01-01

    With the increasing penetration of the wind power, reliable operation and cost-effective wind energy production are of more and more importance. As one of the promising configurations, the cost on reliability and production losses of permanent-magnet synchronous generator based full-scale wind......, if the specific designed wind turbine system operates at different wind classes, it can be seen that higher wind class level results in lower lifetime of the power converter. In respect to the cost of the reactive power, either the OE or the UE reactive power increases the energy loss per year significantly...... power converter is studied considering the grid code with reactive power production as well as the annual wind profile. Regarding the reliability, it is found that either the Over-Excited (OE) or the Under-Excited (UE) reactive power injection threatens the lifespan under all wind classes. Meanwhile...

  8. Dynamically Authorized Role-Based Access Control for Grid Applications

    Institute of Scientific and Technical Information of China (English)

    YAO Hanbing; HU Heping; LU Zhengding; LI Ruixuan

    2006-01-01

    Grid computing is concerned with the sharing and coordinated use of diverse resources in distributed "virtual organizations". The heterogeneous, dynamic and multi-domain nature of these environments makes challenging security issues that demand new technical approaches. Despite the recent advances in access control approaches applicable to Grid computing, there remain issues that impede the development of effective access control models for Grid applications. Among them there are the lack of context-based models for access control, and reliance on identity or capability-based access control schemes. An access control scheme that resolve these issues is presented, and a dynamically authorized role-based access control (D-RBAC) model extending the RBAC with context constraints is proposed. The D-RABC mechanisms dynamically grant permissions to users based on a set of contextual information collected from the system and user's environments, while retaining the advantages of RBAC model. The implementation architecture of D-RBAC for the Grid application is also described.

  9. Improved delayed signal cancellation-based SRF-PLL for unbalanced grid

    DEFF Research Database (Denmark)

    Messo, Tuomas; Sihvo, Jussi; Yang, Dongsheng

    2017-01-01

    Problems with power quality in the grid have gained a lot of attention recently due to rapid increase in the amount of grid-connected power converters. The converter should produce sinusoidal currents also during abnormal conditions, such as unbalanced grid voltages. Several methods, like...... the delayed signal cancellation-based method (DSC), have been proposed to alleviate the detrimental effect of unbalance. This paper proposes an improvement to a delayed signal cancellation based synchronization algorithm for unbalanced grids. The proposed PLL structure employs only half of the delay required...

  10. Grid portal-based data management for lattice QCD data

    Energy Technology Data Exchange (ETDEWEB)

    Andronico, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Catania, via S. Sofia 64, 95123 Catania (Italy)]. E-mail: giuseppe.andronico@ct.infn.it; Barbera, R. [Istituto Nazionale di Fisica Nucleare, Sezione di Catania, via S. Sofia 64, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia dell' Universita di Catania, via S. Sofia 64, 95123 Catania (Italy); Falzone, A. [NICE SRL, via Marchesi di Roero 1, 14020 Cortanze (Italy)

    2004-11-21

    We describe here a case of the European Union DataGrid Project data management services by a Lattice Quantum ChromoDynamics (LQCD) application to share the large amount of configurations generated and based on a solution developed from the International Lattice Data Grid Project using a XML dialect called QCDML. In order to allow the user to store, search and browse the lattice configurations described by QCDML in an uniform and transparent way, we have exploited the functionalities of the GENIUS Grid portal, jointly developed by INFN and NICE srl in the context of the Italian INFN Grid and EU DataGrid Projects.

  11. Grid portal-based data management for lattice QCD data

    International Nuclear Information System (INIS)

    Andronico, G.; Barbera, R.; Falzone, A.

    2004-01-01

    We describe here a case of the European Union DataGrid Project data management services by a Lattice Quantum ChromoDynamics (LQCD) application to share the large amount of configurations generated and based on a solution developed from the International Lattice Data Grid Project using a XML dialect called QCDML. In order to allow the user to store, search and browse the lattice configurations described by QCDML in an uniform and transparent way, we have exploited the functionalities of the GENIUS Grid portal, jointly developed by INFN and NICE srl in the context of the Italian INFN Grid and EU DataGrid Projects

  12. Grist: Grid-based Data Mining for Astronomy

    Science.gov (United States)

    Jacob, J. C.; Katz, D. S.; Miller, C. D.; Walia, H.; Williams, R. D.; Djorgovski, S. G.; Graham, M. J.; Mahabal, A. A.; Babu, G. J.; vanden Berk, D. E.; Nichol, R.

    2005-12-01

    The Grist project is developing a grid-technology based system as a research environment for astronomy with massive and complex datasets. This knowledge extraction system will consist of a library of distributed grid services controlled by a workflow system, compliant with standards emerging from the grid computing, web services, and virtual observatory communities. This new technology is being used to find high redshift quasars, study peculiar variable objects, search for transients in real time, and fit SDSS QSO spectra to measure black hole masses. Grist services are also a component of the ``hyperatlas'' project to serve high-resolution multi-wavelength imagery over the Internet. In support of these science and outreach objectives, the Grist framework will provide the enabling fabric to tie together distributed grid services in the areas of data access, federation, mining, subsetting, source extraction, image mosaicking, statistics, and visualization.

  13. Grist : grid-based data mining for astronomy

    Science.gov (United States)

    Jacob, Joseph C.; Katz, Daniel S.; Miller, Craig D.; Walia, Harshpreet; Williams, Roy; Djorgovski, S. George; Graham, Matthew J.; Mahabal, Ashish; Babu, Jogesh; Berk, Daniel E. Vanden; hide

    2004-01-01

    The Grist project is developing a grid-technology based system as a research environment for astronomy with massive and complex datasets. This knowledge extraction system will consist of a library of distributed grid services controlled by a workflow system, compliant with standards emerging from the grid computing, web services, and virtual observatory communities. This new technology is being used to find high redshift quasars, study peculiar variable objects, search for transients in real time, and fit SDSS QSO spectra to measure black hole masses. Grist services are also a component of the 'hyperatlas' project to serve high-resolution multi-wavelength imagery over the Internet. In support of these science and outreach objectives, the Grist framework will provide the enabling fabric to tie together distributed grid services in the areas of data access, federation, mining, subsetting, source extraction, image mosaicking, statistics, and visualization.

  14. Grid generation methods

    CERN Document Server

    Liseikin, Vladimir D

    2017-01-01

    This new edition provides a description of current developments relating to grid methods, grid codes, and their applications to actual problems. Grid generation methods are indispensable for the numerical solution of differential equations. Adaptive grid-mapping techniques, in particular, are the main focus and represent a promising tool to deal with systems with singularities. This 3rd edition includes three new chapters on numerical implementations (10), control of grid properties (11), and applications to mechanical, fluid, and plasma related problems (13). Also the other chapters have been updated including new topics, such as curvatures of discrete surfaces (3). Concise descriptions of hybrid mesh generation, drag and sweeping methods, parallel algorithms for mesh generation have been included too. This new edition addresses a broad range of readers: students, researchers, and practitioners in applied mathematics, mechanics, engineering, physics and other areas of applications.

  15. Research on the comparison of extension mechanism of cellular automaton based on hexagon grid and rectangular grid

    Science.gov (United States)

    Zhai, Xiaofang; Zhu, Xinyan; Xiao, Zhifeng; Weng, Jie

    2009-10-01

    Historically, cellular automata (CA) is a discrete dynamical mathematical structure defined on spatial grid. Research on cellular automata system (CAS) has focused on rule sets and initial condition and has not discussed its adjacency. Thus, the main focus of our study is the effect of adjacency on CA behavior. This paper is to compare rectangular grids with hexagonal grids on their characteristics, strengths and weaknesses. They have great influence on modeling effects and other applications including the role of nearest neighborhood in experimental design. Our researches present that rectangular and hexagonal grids have different characteristics. They are adapted to distinct aspects, and the regular rectangular or square grid is used more often than the hexagonal grid. But their relative merits have not been widely discussed. The rectangular grid is generally preferred because of its symmetry, especially in orthogonal co-ordinate system and the frequent use of raster from Geographic Information System (GIS). However, in terms of complex terrain, uncertain and multidirectional region, we have preferred hexagonal grids and methods to facilitate and simplify the problem. Hexagonal grids can overcome directional warp and have some unique characteristics. For example, hexagonal grids have a simpler and more symmetric nearest neighborhood, which avoids the ambiguities of the rectangular grids. Movement paths or connectivity, the most compact arrangement of pixels, make hexagonal appear great dominance in the process of modeling and analysis. The selection of an appropriate grid should be based on the requirements and objectives of the application. We use rectangular and hexagonal grids respectively for developing city model. At the same time we make use of remote sensing images and acquire 2002 and 2005 land state of Wuhan. On the base of city land state in 2002, we make use of CA to simulate reasonable form of city in 2005. Hereby, these results provide a proof of

  16. Optimal, Reliability-Based Code Calibration

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    2002-01-01

    Reliability based code calibration is considered in this paper. It is described how the results of FORM based reliability analysis may be related to the partial safety factors and characteristic values. The code calibration problem is presented in a decision theoretical form and it is discussed how...... of reliability based code calibration of LRFD based design codes....

  17. Assessment of systems codes and their coupling with CFD codes in thermal–hydraulic applications to innovative reactors

    Energy Technology Data Exchange (ETDEWEB)

    Bandini, G., E-mail: giacomino.bandini@enea.it [Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) (Italy); Polidori, M. [Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) (Italy); Gerschenfeld, A.; Pialla, D.; Li, S. [Commissariat à l’Energie Atomique (CEA) (France); Ma, W.M.; Kudinov, P.; Jeltsov, M.; Kööp, K. [Royal Institute of Technology (KTH) (Sweden); Huber, K.; Cheng, X.; Bruzzese, C.; Class, A.G.; Prill, D.P. [Karlsruhe Institute of Technology (KIT) (Germany); Papukchiev, A. [Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) (Germany); Geffray, C.; Macian-Juan, R. [Technische Universität München (TUM) (Germany); Maas, L. [Institut de Radioprotection et de Sûreté Nucléaire (IRSN) (France)

    2015-01-15

    Highlights: • The assessment of RELAP5, TRACE and CATHARE system codes on integral experiments is presented. • Code benchmark of CATHARE, DYN2B, and ATHLET on PHENIX natural circulation experiment. • Grid-free pool modelling based on proper orthogonal decomposition for system codes is explained. • The code coupling methodologies are explained. • The coupling of several CFD/system codes is tested against integral experiments. - Abstract: The THINS project of the 7th Framework EU Program on nuclear fission safety is devoted to the investigation of crosscutting thermal–hydraulic issues for innovative nuclear systems. A significant effort in the project has been dedicated to the qualification and validation of system codes currently employed in thermal–hydraulic transient analysis for nuclear reactors. This assessment is based either on already available experimental data, or on the data provided by test campaigns carried out in the frame of THINS project activities. Data provided by TALL and CIRCE facilities were used in the assessment of system codes for HLM reactors, while the PHENIX ultimate natural circulation test was used as reference for a benchmark exercise among system codes for sodium-cooled reactor applications. In addition, a promising grid-free pool model based on proper orthogonal decomposition is proposed to overcome the limits shown by the thermal–hydraulic system codes in the simulation of pool-type systems. Furthermore, multi-scale system-CFD solutions have been developed and validated for innovative nuclear system applications. For this purpose, data from the PHENIX experiments have been used, and data are provided by the tests conducted with new configuration of the TALL-3D facility, which accommodates a 3D test section within the primary circuit. The TALL-3D measurements are currently used for the validation of the coupling between system and CFD codes.

  18. Grid support capabilities of wind turbines

    DEFF Research Database (Denmark)

    Michalke, Gabriele; Hansen, Anca Daniela

    2013-01-01

    Wind power has gained a significant penetration level in several power systems all over the world. Due to this reason modern wind turbines are requested to contribute to power system support. Power system operators have thus introduced grid codes, which specify a set of requirements for wind...... turbines, such as fault ride-through and reactive power supply during voltage sags. To date different wind turbine concepts exist on the market comprising different control features in order to provide ancillary services to the power system. In the first place the present chapter emphasizes the most...... important issues related to wind power grid integration. Then different wind turbine concepts are characterized and their grid support capabilities are analysed and compared. Simulation cases are presented in which the respective wind turbine concepts are subjected to a voltage dip specified in a grid code....

  19. MEDUSA - An overset grid flow solver for network-based parallel computer systems

    Science.gov (United States)

    Smith, Merritt H.; Pallis, Jani M.

    1993-01-01

    Continuing improvement in processing speed has made it feasible to solve the Reynolds-Averaged Navier-Stokes equations for simple three-dimensional flows on advanced workstations. Combining multiple workstations into a network-based heterogeneous parallel computer allows the application of programming principles learned on MIMD (Multiple Instruction Multiple Data) distributed memory parallel computers to the solution of larger problems. An overset-grid flow solution code has been developed which uses a cluster of workstations as a network-based parallel computer. Inter-process communication is provided by the Parallel Virtual Machine (PVM) software. Solution speed equivalent to one-third of a Cray-YMP processor has been achieved from a cluster of nine commonly used engineering workstation processors. Load imbalance and communication overhead are the principal impediments to parallel efficiency in this application.

  20. Loss of Synchronism of Wind Turbine Converters during Low Voltage Grid Faults

    DEFF Research Database (Denmark)

    Göksu, Ömer; Sørensen, Poul Ejnar; Iov, Florin

    2014-01-01

    In the recent grid codes, wind power plants are required to stay connected and inject reactive and active currents during grid short-circuit faults, even when the grid voltage drops down to zero. However, the physical fact, Loss of Synchronism (LOS) of wind turbines during these very low voltage ...... as whole. Additionally, existing methods to solve the LOS problem are briefly reviewed, and a closed loop frequency based solution is implemented within PowerFactory simulations of a detailed generic wind power plant model....

  1. Visualization of Instrumental Verification Information Details (VIVID) : code development, description, and usage.

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Christopher John; Bainbridge, Bruce L.; Potter, Donald L.; Blottner, Frederick G.; Black, Amalia Rebecca

    2005-03-01

    The formulation, implementation and usage of a numerical solution verification code is described. This code uses the Richardson extrapolation procedure to estimate the order of accuracy and error of a computational program solution. It evaluates multiple solutions performed in numerical grid convergence studies to verify a numerical algorithm implementation. Analyses are performed on both structured and unstructured grid codes. Finite volume and finite element discretization programs are examined. Two and three-dimensional solutions are evaluated. Steady state and transient solution analysis capabilities are present in the verification code. Multiple input data bases are accepted. Benchmark options are included to allow for minimal solution validation capability as well as verification.

  2. Validation of a Computational Fluid Dynamics (CFD) Code for Supersonic Axisymmetric Base Flow

    Science.gov (United States)

    Tucker, P. Kevin

    1993-01-01

    The ability to accurately and efficiently calculate the flow structure in the base region of bodies of revolution in supersonic flight is a significant step in CFD code validation for applications ranging from base heating for rockets to drag for protectives. The FDNS code is used to compute such a flow and the results are compared to benchmark quality experimental data. Flowfield calculations are presented for a cylindrical afterbody at M = 2.46 and angle of attack a = O. Grid independent solutions are compared to mean velocity profiles in the separated wake area and downstream of the reattachment point. Additionally, quantities such as turbulent kinetic energy and shear layer growth rates are compared to the data. Finally, the computed base pressures are compared to the measured values. An effort is made to elucidate the role of turbulence models in the flowfield predictions. The level of turbulent eddy viscosity, and its origin, are used to contrast the various turbulence models and compare the results to the experimental data.

  3. Task-and-role-based access-control model for computational grid

    Institute of Scientific and Technical Information of China (English)

    LONG Tao; HONG Fan; WU Chi; SUN Ling-li

    2007-01-01

    Access control in a grid environment is a challenging issue because the heterogeneous nature and independent administration of geographically dispersed resources in grid require access control to use fine-grained policies. We established a task-and-role-based access-control model for computational grid (CG-TRBAC model), integrating the concepts of role-based access control (RBAC) and task-based access control (TBAC). In this model, condition restrictions are defined and concepts specifically tailored to Workflow Management System are simplified or omitted so that role assignment and security administration fit computational grid better than traditional models; permissions are mutable with the task status and system variables, and can be dynamically controlled. The CG-TRBAC model is proved flexible and extendible. It can implement different control policies. It embodies the security principle of least privilege and executes active dynamic authorization. A task attribute can be extended to satisfy different requirements in a real grid system.

  4. Grid synchronization for advanced power processing and FACTS in wind power systems

    DEFF Research Database (Denmark)

    Luna, A.; Rocabert, J.; Vazquez, G.

    2010-01-01

    The high penetration of wind power systems in the electrical network has introduced new issues in the stability and transient operation of the grid. By means of providing advanced functionalities to the existing power converters of such power plants it is possible to enhance their performance...... and also to support the grid operation, as the new grid codes demand. The connection of FACTS based on power converters, such as STATCOMs, are also contributing to the integration of renewable energies improving their behavior under contingencies. However, in both cases it is needed to have a grid voltage...

  5. Fast and accurate grid representations for atom-based docking with partner flexibility.

    Science.gov (United States)

    de Vries, Sjoerd J; Zacharias, Martin

    2017-06-30

    Macromolecular docking methods can broadly be divided into geometric and atom-based methods. Geometric methods use fast algorithms that operate on simplified, grid-like molecular representations, while atom-based methods are more realistic and flexible, but far less efficient. Here, a hybrid approach of grid-based and atom-based docking is presented, combining precalculated grid potentials with neighbor lists for fast and accurate calculation of atom-based intermolecular energies and forces. The grid representation is compatible with simultaneous multibody docking and can tolerate considerable protein flexibility. When implemented in our docking method ATTRACT, grid-based docking was found to be ∼35x faster. With the OPLSX forcefield instead of the ATTRACT coarse-grained forcefield, the average speed improvement was >100x. Grid-based representations may allow atom-based docking methods to explore large conformational spaces with many degrees of freedom, such as multiple macromolecules including flexibility. This increases the domain of biological problems to which docking methods can be applied. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  6. Grid-based electronic structure calculations: The tensor decomposition approach

    Energy Technology Data Exchange (ETDEWEB)

    Rakhuba, M.V., E-mail: rakhuba.m@gmail.com [Skolkovo Institute of Science and Technology, Novaya St. 100, 143025 Skolkovo, Moscow Region (Russian Federation); Oseledets, I.V., E-mail: i.oseledets@skoltech.ru [Skolkovo Institute of Science and Technology, Novaya St. 100, 143025 Skolkovo, Moscow Region (Russian Federation); Institute of Numerical Mathematics, Russian Academy of Sciences, Gubkina St. 8, 119333 Moscow (Russian Federation)

    2016-05-01

    We present a fully grid-based approach for solving Hartree–Fock and all-electron Kohn–Sham equations based on low-rank approximation of three-dimensional electron orbitals. Due to the low-rank structure the total complexity of the algorithm depends linearly with respect to the one-dimensional grid size. Linear complexity allows for the usage of fine grids, e.g. 8192{sup 3} and, thus, cheap extrapolation procedure. We test the proposed approach on closed-shell atoms up to the argon, several molecules and clusters of hydrogen atoms. All tests show systematical convergence with the required accuracy.

  7. GIS embedded hydrological modeling: the SID&GRID project

    Science.gov (United States)

    Borsi, I.; Rossetto, R.; Schifani, C.

    2012-04-01

    The SID&GRID research project, started April 2010 and funded by Regione Toscana (Italy) under the POR FSE 2007-2013, aims to develop a Decision Support System (DSS) for water resource management and planning based on open source and public domain solutions. In order to quantitatively assess water availability in space and time and to support the planning decision processes, the SID&GRID solution consists of hydrological models (coupling 3D existing and newly developed surface- and ground-water and unsaturated zone modeling codes) embedded in a GIS interface, applications and library, where all the input and output data are managed by means of DataBase Management System (DBMS). A graphical user interface (GUI) to manage, analyze and run the SID&GRID hydrological models based on open source gvSIG GIS framework (Asociación gvSIG, 2011) and a Spatial Data Infrastructure to share and interoperate with distributed geographical data is being developed. Such a GUI is thought as a "master control panel" able to guide the user from pre-processing spatial and temporal data, running the hydrological models, and analyzing the outputs. To achieve the above-mentioned goals, the following codes have been selected and are being integrated: 1. Postgresql/PostGIS (PostGIS, 2011) for the Geo Data base Management System; 2. gvSIG with Sextante (Olaya, 2011) geo-algorithm library capabilities and Grass tools (GRASS Development Team, 2011) for the desktop GIS; 3. Geoserver and Geonetwork to share and discover spatial data on the web according to Open Geospatial Consortium; 4. new tools based on the Sextante GeoAlgorithm framework; 5. MODFLOW-2005 (Harbaugh, 2005) groundwater modeling code; 6. MODFLOW-LGR (Mehl and Hill 2005) for local grid refinement; 7. VSF (Thoms et al., 2006) for the variable saturated flow component; 8. new developed routines for overland flow; 9. new algorithms in Jython integrated in gvSIG to compute the net rainfall rate reaching the soil surface, as input for

  8. ALCBEAM - Neutral beam formation and propagation code for beam-based plasma diagnostics

    Science.gov (United States)

    Bespamyatnov, I. O.; Rowan, W. L.; Liao, K. T.

    2012-03-01

    ALCBEAM is a new three-dimensional neutral beam formation and propagation code. It was developed to support the beam-based diagnostics installed on the Alcator C-Mod tokamak. The purpose of the code is to provide reliable estimates of the local beam equilibrium parameters: such as beam energy fractions, density profiles and excitation populations. The code effectively unifies the ion beam formation, extraction and neutralization processes with beam attenuation and excitation in plasma and neutral gas and beam stopping by the beam apertures. This paper describes the physical processes interpreted and utilized by the code, along with exploited computational methods. The description is concluded by an example simulation of beam penetration into plasma of Alcator C-Mod. The code is successfully being used in Alcator C-Mod tokamak and expected to be valuable in the support of beam-based diagnostics in most other tokamak environments. Program summaryProgram title: ALCBEAM Catalogue identifier: AEKU_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKU_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 66 459 No. of bytes in distributed program, including test data, etc.: 7 841 051 Distribution format: tar.gz Programming language: IDL Computer: Workstation, PC Operating system: Linux RAM: 1 GB Classification: 19.2 Nature of problem: Neutral beams are commonly used to heat and/or diagnose high-temperature magnetically-confined laboratory plasmas. An accurate neutral beam characterization is required for beam-based measurements of plasma properties. Beam parameters such as density distribution, energy composition, and atomic excited populations of the beam atoms need to be known. Solution method: A neutral beam is initially formed as an ion beam which is extracted from

  9. A data grid for imaging-based clinical trials

    Science.gov (United States)

    Zhou, Zheng; Chao, Sander S.; Lee, Jasper; Liu, Brent; Documet, Jorge; Huang, H. K.

    2007-03-01

    Clinical trials play a crucial role in testing new drugs or devices in modern medicine. Medical imaging has also become an important tool in clinical trials because images provide a unique and fast diagnosis with visual observation and quantitative assessment. A typical imaging-based clinical trial consists of: 1) A well-defined rigorous clinical trial protocol, 2) a radiology core that has a quality control mechanism, a biostatistics component, and a server for storing and distributing data and analysis results; and 3) many field sites that generate and send image studies to the radiology core. As the number of clinical trials increases, it becomes a challenge for a radiology core servicing multiple trials to have a server robust enough to administrate and quickly distribute information to participating radiologists/clinicians worldwide. The Data Grid can satisfy the aforementioned requirements of imaging based clinical trials. In this paper, we present a Data Grid architecture for imaging-based clinical trials. A Data Grid prototype has been implemented in the Image Processing and Informatics (IPI) Laboratory at the University of Southern California to test and evaluate performance in storing trial images and analysis results for a clinical trial. The implementation methodology and evaluation protocol of the Data Grid are presented.

  10. State-space-based harmonic stability analysis for paralleled grid-connected inverters

    DEFF Research Database (Denmark)

    Wang, Yanbo; Wang, Xiongfei; Chen, Zhe

    2016-01-01

    This paper addresses a state-space-based harmonic stability analysis of paralleled grid-connected inverters system. A small signal model of individual inverter is developed, where LCL filter, the equivalent delay of control system, and current controller are modeled. Then, the overall small signal...... model of paralleled grid-connected inverters is built. Finally, the state space-based stability analysis approach is developed to explain the harmonic resonance phenomenon. The eigenvalue traces associated with time delay and coupled grid impedance are obtained, which accounts for how the unstable...... inverter produces the harmonic resonance and leads to the instability of whole paralleled system. The proposed approach reveals the contributions of the grid impedance as well as the coupled effect on other grid-connected inverters under different grid conditions. Simulation and experimental results...

  11. Wind power integration in island-based smart grid projects : A comparative study between Jeju Smart Grid Test-bed and Smart Grid Gotland

    OpenAIRE

    Piehl, Hampus

    2014-01-01

    Smart grids seem to be the solution to use energy from renewable and intermittent energy sources in an efficient manner. There are many research projects around the world and two of them are Jeju Smart Grid Test-bed and Smart Grid Gotland. They have in common that they are both island-based projects and connected to the Powergrid on the mainland by HVDC-link. The purpose of this thesis is to compare the two projects and find out what challenges and strategies they have related to wind power i...

  12. Goya - an MHD equilibrium code for toroidal plasmas

    International Nuclear Information System (INIS)

    Scheffel, J.

    1984-09-01

    A description of the GOYA free-boundary equilibrium code is given. The non-linear Grad-Shafranov equation of ideal MHD is solved in a toroidal geometry for plasmas with purely poloidal magnetic fields. The code is based on a field line-tracing procedure, making storage of a large amount of information on a grid unnecessary. Usage of the code is demonstrated by computations of equi/libria for the EXTRAP-T1 device. (Author)

  13. Frequency scanning-based stability analysis method for grid-connected inverter system

    DEFF Research Database (Denmark)

    Wang, Yanbo; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    This paper proposes a frequency scanning-based impedance analysis for stability assessment of grid-connected inverter system, which is able to perform stability assessment without using system mathematical models and inherit the superior feature of impedance-based stability criterion with conside......This paper proposes a frequency scanning-based impedance analysis for stability assessment of grid-connected inverter system, which is able to perform stability assessment without using system mathematical models and inherit the superior feature of impedance-based stability criterion...... with consideration of the inverter nonlinearities. Small current disturbance is injected into grid-connected inverter system in a particular frequency range, and the impedance is computed according to the harmonic-frequency response using Fourier analysis, and then the stability is predicted on the basis...... of the impedance stability criterion. The stability issues of grid-connected inverters with grid-current feedback and the converter-current feedback are addressed using the proposed method. The results obtained from simulation and experiments validate the effectiveness of the method. The frequency scanning...

  14. Wingridder - an interactive grid generator for TOUGH2

    International Nuclear Information System (INIS)

    Pan, Lehua

    2003-01-01

    The TOUGH (Transport Of Unsaturated Groundwater and Heat) family of codes has great flexibility in handling the variety of grid information required to describe a complex subsurface system. However, designing and generating such a grid can be a tedious and error-prone process. This is especially true when the number of cells and connections is very large. As a user-friendly, efficient, and effective grid generating software, WinGridder has been developed for designing, generating, and visualizing (at various spatial scales) numerical grids used in reservoir simulations and groundwater modeling studies. It can save mesh files for TOUGH family codes. It can also output additional grid information for various purposes in either graphic format or plain text format. It has user-friendly graphical user interfaces, along with an easy-to-use interactive design and plot tools. Many important features, such as inclined faults and offset, layering structure, local refinements, and embedded engineering structures, can be represented in the grid

  15. Reinforcement Learning Based Novel Adaptive Learning Framework for Smart Grid Prediction

    Directory of Open Access Journals (Sweden)

    Tian Li

    2017-01-01

    Full Text Available Smart grid is a potential infrastructure to supply electricity demand for end users in a safe and reliable manner. With the rapid increase of the share of renewable energy and controllable loads in smart grid, the operation uncertainty of smart grid has increased briskly during recent years. The forecast is responsible for the safety and economic operation of the smart grid. However, most existing forecast methods cannot account for the smart grid due to the disabilities to adapt to the varying operational conditions. In this paper, reinforcement learning is firstly exploited to develop an online learning framework for the smart grid. With the capability of multitime scale resolution, wavelet neural network has been adopted in the online learning framework to yield reinforcement learning and wavelet neural network (RLWNN based adaptive learning scheme. The simulations on two typical prediction problems in smart grid, including wind power prediction and load forecast, validate the effectiveness and the scalability of the proposed RLWNN based learning framework and algorithm.

  16. Advanced fault ride-through control of DFIG based wind turbines including grid connection via VSC-HVDC

    Energy Technology Data Exchange (ETDEWEB)

    Feltes, Christian

    2012-07-01

    With the growing renewable energy share in the power generation mix it becomes inevitable that also these new generation technologies participate on the provision of grid services to guarantee stable operation of the grid, especially when one considers the decreasing number of conventional power plants in operation as a result of the expansion of wind based generation plants. These so-called ancillary services include frequency / active power control, voltage / reactive power control and fault ride-through (FRT) with fast voltage control and are stipulated in modern grid codes. In the context of this thesis advanced control algorithms have been developed for wind turbines based on doubly-fed induction generator (DFIG) to allow safe FRT during symmetrical and unsymmetrical faults. This covers the control for conventional AC grid connection as well as for the connection through voltage source converter (VSC) based high voltage direct current transmission (HVDC). Currently, the DFIG is the most used generator technology in modem wind turbines, since it combines a relatively simple slip-ring induction machine with a frequency converter rated to only approx. 30% of the total power. This makes the DFIG a cost-effective concept, which offers a variable speed range and a high degree of flexibility in control. However, due to the direct coupling of the generator stator circuit to the grid, grid faults are a special challenge for the frequency converter, its protection circuits and control algorithms. As base for the detailed evaluation of the impact of grid faults to the DFIG, this thesis contains the analytical derivation of the DFIG short circuit currents under consideration of frequency converter control. The DFIG concept presented in this thesis makes use of a DC chopper in the frequency converter, which allows safe FRT with grid voltage support through both converter sides. The developed control contains a new algorithm for a clear separation and control of positive

  17. AVQS: Attack Route-Based Vulnerability Quantification Scheme for Smart Grid

    Directory of Open Access Journals (Sweden)

    Jongbin Ko

    2014-01-01

    Full Text Available A smart grid is a large, consolidated electrical grid system that includes heterogeneous networks and systems. Based on the data, a smart grid system has a potential security threat in its network connectivity. To solve this problem, we develop and apply a novel scheme to measure the vulnerability in a smart grid domain. Vulnerability quantification can be the first step in security analysis because it can help prioritize the security problems. However, existing vulnerability quantification schemes are not suitable for smart grid because they do not consider network vulnerabilities. We propose a novel attack route-based vulnerability quantification scheme using a network vulnerability score and an end-to-end security score, depending on the specific smart grid network environment to calculate the vulnerability score for a particular attack route. To evaluate the proposed approach, we derive several attack scenarios from the advanced metering infrastructure domain. The experimental results of the proposed approach and the existing common vulnerability scoring system clearly show that we need to consider network connectivity for more optimized vulnerability quantification.

  18. AVQS: attack route-based vulnerability quantification scheme for smart grid.

    Science.gov (United States)

    Ko, Jongbin; Lim, Hyunwoo; Lee, Seokjun; Shon, Taeshik

    2014-01-01

    A smart grid is a large, consolidated electrical grid system that includes heterogeneous networks and systems. Based on the data, a smart grid system has a potential security threat in its network connectivity. To solve this problem, we develop and apply a novel scheme to measure the vulnerability in a smart grid domain. Vulnerability quantification can be the first step in security analysis because it can help prioritize the security problems. However, existing vulnerability quantification schemes are not suitable for smart grid because they do not consider network vulnerabilities. We propose a novel attack route-based vulnerability quantification scheme using a network vulnerability score and an end-to-end security score, depending on the specific smart grid network environment to calculate the vulnerability score for a particular attack route. To evaluate the proposed approach, we derive several attack scenarios from the advanced metering infrastructure domain. The experimental results of the proposed approach and the existing common vulnerability scoring system clearly show that we need to consider network connectivity for more optimized vulnerability quantification.

  19. WinGridder - An interactive grid generator for TOUGH - A user's manual (Version 1.0)

    International Nuclear Information System (INIS)

    Pan, Lehua; Hinds, Jennifer; Haukwa, Charles; Wu, Yu-Shu; Bodvarsson, Gudmundur

    2001-01-01

    WinGridder is a Windows-based software package for designing, generating, and visualizing at various spatial scales numerical grids used in reservoir simulations and groundwater modeling studies. Development of this software was motivated by the requirements of the TOUGH (Transport of Unsaturated Groundwater and Heat) family of codes (Pruess 1987, 1991) for simulating subsurface processes related to high-level nuclear waste isolation in partially saturated geological media. Although the TOUGH family of codes has great flexibility in handling the variety of grid information required to describe complex objects, designing and generating a suitable irregular grid can be a tedious and error-prone process, even with the help of existing grid generating programs. This is especially true when the number of cells and connections is very large. The processes of inspecting the quality of the grid or extracting sub-grids or other specific grid information are also complex. The mesh maker embedded within TOUGH2 generates only uniform numerical grids and handles only one set of uniform fracture and matrix properties throughout the model domain. This is not suitable for grid generation in complex flow and transport simulations (such as those of Yucca Mountain, which have heterogeneity in both fracture and matrix media). As a result, the software program Amesh (Haukwa 2000) was developed to generate irregular, effective-continuum (ECM) grids

  20. Grid Monitoring and Advanced Control of Distributed Power Generation Systems

    DEFF Research Database (Denmark)

    Timbus, Adrian Vasile

    . As an example, the latest published grid codes stress the ability of distributed generators, especially wind turbines, to stay connected during short grid disturbances and in addition to provide active/reactive power control at the point of common coupling. Based on the above facts, the need for improving...... reported in some countries creating concerns about power system stability. This leads to a continuous evolution of grid interconnection requirements towards a better controllability of generated power and an enhanced contribution of distributed power generation systems to power system stability...... and adding more features to the control of distributed power generation systems (DPGS) arises. As a consequence, this thesis focuses on grid monitoring methods and possible approaches in control in order to obtain a more reliable and  exible power generation system during normal and faulty grid conditions...

  1. Synchronization of grid-connected renewable energy sources under highly distorted voltages and unbalanced grid faults

    DEFF Research Database (Denmark)

    Hadjidemetriou, Lenos; Kyriakides, Elias; Blaabjerg, Frede

    2013-01-01

    Renewable energy sources require accurate and appropriate performance not only under normal grid operation but also under abnormal and faulty grid conditions according to the modern grid codes. This paper proposes a novel phase-locked loop algorithm (MSHDC-PLL), which can enable the fast...... and dynamic synchronization of the interconnected renewable energy system under unbalanced grid faults and under highly harmonic distorted voltage. The outstanding performance of the suggested PLL is achieved by implementing an innovative multi-sequence/harmonic decoupling cell in order to dynamically cancel...... renewable energy systems. Therefore, the performance of the new PLL can increase the quality of the injected power under abnormal conditions and in addition enable the renewable energy systems to provide the appropriate support to the grid under balanced and unbalanced grid faults....

  2. Schwarz-Christoffel Conformal Mapping based Grid Generation for Global Oceanic Circulation Models

    Science.gov (United States)

    Xu, Shiming

    2015-04-01

    We propose new grid generation algorithms for global ocean general circulation models (OGCMs). Contrary to conventional, analytical forms based dipolar or tripolar grids, the new algorithm are based on Schwarz-Christoffel (SC) conformal mapping with prescribed boundary information. While dealing with the conventional grid design problem of pole relocation, it also addresses more advanced issues of computational efficiency and the new requirements on OGCM grids arisen from the recent trend of high-resolution and multi-scale modeling. The proposed grid generation algorithm could potentially achieve the alignment of grid lines to coastlines, enhanced spatial resolution in coastal regions, and easier computational load balance. Since the generated grids are still orthogonal curvilinear, they can be readily 10 utilized in existing Bryan-Cox-Semtner type ocean models. The proposed methodology can also be applied to the grid generation task for regional ocean modeling when complex land-ocean distribution is present.

  3. National Fusion Collaboratory: Grid Computing for Simulations and Experiments

    Science.gov (United States)

    Greenwald, Martin

    2004-05-01

    The National Fusion Collaboratory Project is creating a computational grid designed to advance scientific understanding and innovation in magnetic fusion research by facilitating collaborations, enabling more effective integration of experiments, theory and modeling and allowing more efficient use of experimental facilities. The philosophy of FusionGrid is that data, codes, analysis routines, visualization tools, and communication tools should be thought of as network available services, easily used by the fusion scientist. In such an environment, access to services is stressed rather than portability. By building on a foundation of established computer science toolkits, deployment time can be minimized. These services all share the same basic infrastructure that allows for secure authentication and resource authorization which allows stakeholders to control their own resources such as computers, data and experiments. Code developers can control intellectual property, and fair use of shared resources can be demonstrated and controlled. A key goal is to shield scientific users from the implementation details such that transparency and ease-of-use are maximized. The first FusionGrid service deployed was the TRANSP code, a widely used tool for transport analysis. Tools for run preparation, submission, monitoring and management have been developed and shared among a wide user base. This approach saves user sites from the laborious effort of maintaining such a large and complex code while at the same time reducing the burden on the development team by avoiding the need to support a large number of heterogeneous installations. Shared visualization and A/V tools are being developed and deployed to enhance long-distance collaborations. These include desktop versions of the Access Grid, a highly capable multi-point remote conferencing tool and capabilities for sharing displays and analysis tools over local and wide-area networks.

  4. A Comparison of Grid-based and SPH Binary Mass-transfer and Merger Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Motl, Patrick M. [Indiana University Kokomo, School of Sciences, P.O. Box 9003, Kokomo, IN 46903-9004 (United States); Frank, Juhan; Clayton, Geoffrey C.; Tohline, Joel E. [Louisiana State University, Department of Physics and Astronomy, 202 Nicholson Hall, Baton Rouge, LA 70803-4001 (United States); Staff, Jan [College of Science and Math, University of Virgin Islands, St. Thomas, United States Virgin Islands 00802 (United States); Fryer, Christopher L.; Even, Wesley [Center for Theoretical Astrophysics/CCS-2, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States); Diehl, Steven, E-mail: pmotl@iuk.edu [TLT-Turbo GmbH, Gleiwitzstrasse 7, 66482 Zweibrücken (Germany)

    2017-04-01

    There is currently a great amount of interest in the outcomes and astrophysical implications of mergers of double degenerate binaries. In a commonly adopted approximation, the components of such binaries are represented by polytropes with an index of n  = 3/2. We present detailed comparisons of stellar mass-transfer and merger simulations of polytropic binaries that have been carried out using two very different numerical algorithms—a finite-volume “grid” code and a smoothed-particle hydrodynamics (SPH) code. We find that there is agreement in both the ultimate outcomes of the evolutions and the intermediate stages if the initial conditions for each code are chosen to match as closely as possible. We find that even with closely matching initial setups, the time it takes to reach a concordant evolution differs between the two codes because the initial depth of contact cannot be matched exactly. There is a general tendency for SPH to yield higher mass transfer rates and faster evolution to the final outcome. We also present comparisons of simulations calculated from two different energy equations: in one series, we assume a polytropic equation of state and in the other series an ideal gas equation of state. In the latter series of simulations, an atmosphere forms around the accretor, which can exchange angular momentum and cause a more rapid loss of orbital angular momentum. In the simulations presented here, the effect of the ideal equation of state is to de-stabilize the binary in both SPH and grid simulations, but the effect is more pronounced in the grid code.

  5. An Efficient Audio Coding Scheme for Quantitative and Qualitative Large Scale Acoustic Monitoring Using the Sensor Grid Approach

    Directory of Open Access Journals (Sweden)

    Félix Gontier

    2017-11-01

    Full Text Available The spreading of urban areas and the growth of human population worldwide raise societal and environmental concerns. To better address these concerns, the monitoring of the acoustic environment in urban as well as rural or wilderness areas is an important matter. Building on the recent development of low cost hardware acoustic sensors, we propose in this paper to consider a sensor grid approach to tackle this issue. In this kind of approach, the crucial question is the nature of the data that are transmitted from the sensors to the processing and archival servers. To this end, we propose an efficient audio coding scheme based on third octave band spectral representation that allows: (1 the estimation of standard acoustic indicators; and (2 the recognition of acoustic events at state-of-the-art performance rate. The former is useful to provide quantitative information about the acoustic environment, while the latter is useful to gather qualitative information and build perceptually motivated indicators using for example the emergence of a given sound source. The coding scheme is also demonstrated to transmit spectrally encoded data that, reverted to the time domain using state-of-the-art techniques, are not intelligible, thus protecting the privacy of citizens.

  6. dSPACE based adaptive neuro-fuzzy controller of grid interactive inverter

    International Nuclear Information System (INIS)

    Altin, Necmi; Sefa, İbrahim

    2012-01-01

    Highlights: ► We propose a dSPACE based neuro-fuzzy controlled grid interactive inverter. ► The membership functions and rule base of fuzzy logic controller by using ANFIS. ► A LCL output filter is designed. ► A high performance controller is designed. - Abstract: In this study, design, simulation and implementation of a dSPACE based grid interactive voltage source inverter are proposed. This inverter has adaptive neuro-fuzzy controller and capable of importing electrical energy, generated from renewable energy sources such as the wind, the solar and the fuel cells to the grid. A line frequency transformer and a LCL filter are used at the output of the grid interactive inverter which is designed as current controlled to decrease the susceptibility to phase errors. Membership functions and rule base of the fuzzy logic controller, which control the inverter output current, are determined by using artificial neural networks. Both simulation and experimental results show that, the grid interactive inverter operates synchronously with the grid. The inverter output current which is imported to the grid is in sinusoidal waveform and the harmonic level of it meets the international standards (4.3 < 5.0%). In addition, simulation and experimental results of the neuro-fuzzy and the PI controlled inverter are given together and compared in detail. Simulation and experimental results show that the proposed inverter has faster response to the reference variations and lower steady state error than PI controller.

  7. Doubly Fed Induction Generator Wind Turbine Systems Subject to Recurring Symmetrical Grid Faults

    DEFF Research Database (Denmark)

    Chen, Wenjie; Blaabjerg, Frede; Zhu, Nan

    2016-01-01

    New grid codes demand the wind turbine systems to ride through recurring grid faults. In this paper, the performance of the doubly Ffed induction generator (DFIG) wind turbine system under recurring symmetrical grid faults is analyzed. The mathematical model of the DFIG under recurring symmetrical...... grid faults is established. The analysis is based on the DFIG wind turbine system with the typical low-voltage ride-through strategy-with rotor-side crowbar. The stator natural flux produced by the voltage recovery after the first grid fault may be superposed on the stator natural flux produced...... by the second grid fault, so that the transient rotor and stator current and torque fluctuations under the second grid fault may be influenced by the characteristic of the first grid fault, including the voltage dips level and the grid fault angle, as well as the duration between two faults. The mathematical...

  8. Control of Wind Turbines during Symmetrical and Asymmetrical Grid Faults

    DEFF Research Database (Denmark)

    Göksu, Ömer

    As installed capacity of the wind power plants (WPPs) in power system of certain countries increases, stability of the power system becomes more critical. In order to sustain stable power system operation with high share of wind power, system operators of some countries are enforcing more stringent...... grid code requirements, which are targeting to make the WPPs operate in a closer manner to the conventional power plants. Common to most of the grid codes, WPPs are required to stay connected during short-circuit grid faults, and also inject reactive current in order to support the grid voltage...... type wind turbines (WTs), in an AC connected WPP, is investigated and control algorithms are designed for minimum disrupted operation and improved grid support, for both symmetrical and asymmetrical grid faults. WTs’ response with conventional control algorithms is studied regarding the impact...

  9. Hybrid method based on embedded coupled simulation of vortex particles in grid based solution

    Science.gov (United States)

    Kornev, Nikolai

    2017-09-01

    The paper presents a novel hybrid approach developed to improve the resolution of concentrated vortices in computational fluid mechanics. The method is based on combination of a grid based and the grid free computational vortex (CVM) methods. The large scale flow structures are simulated on the grid whereas the concentrated structures are modeled using CVM. Due to this combination the advantages of both methods are strengthened whereas the disadvantages are diminished. The procedure of the separation of small concentrated vortices from the large scale ones is based on LES filtering idea. The flow dynamics is governed by two coupled transport equations taking two-way interaction between large and fine structures into account. The fine structures are mapped back to the grid if their size grows due to diffusion. Algorithmic aspects of the hybrid method are discussed. Advantages of the new approach are illustrated on some simple two dimensional canonical flows containing concentrated vortices.

  10. Agent based approach for engineering and control of micro-grids

    International Nuclear Information System (INIS)

    Basso, Gillian

    2013-01-01

    Energy management is, nowadays, a subject of uttermost importance. Indeed, we are facing growing concerns such as petroleum reserve depletion, earth global warming or power quality (e.g. avoiding blackouts during peak times). Smart grids is an attempt to solve such problems, by adding to power grids bidirectional communications and ICT capabilities in order to provide an intelligent autonomic management for the grid. This thesis focuses on the management of micro-grids thanks to multi-agent systems (MAS). Micro-grids are low-power networks, composed of small and decentralized energy producers (possibly renewable) and consumers. These networks can be connected to the main grid or islanded, this make them more complex. Due to their complexity and their geographical distribution, smart grids and micro-grids can not be easily managed by a centralized system. Distributed artificial intelligences especially MAS appear to be a solution to resolve problems related to smart grids. Firstly we defined an approach implementing feedback loops. These feedback loops exist in complex systems which can be defined with several abstraction levels. Two levels are interacting. The micro-level contains a set of agents owning behaviours that can be combined. The result of the combination impact the state of the system. The macro-level processes these influences to define a new state of the system which will impact the agents behaviours at the micro-level. This feedback loop separates behaviours on several levels. This approach is used to defined a demand and supply matching problem in micro-grid. This problem afford to manage a set of goals which currently are independently processed. Finally, an application is developed using MAS that ensures grid stability thanks to storage systems. This application was thought to be integrated to the approach detailed above. Secondly, a grid simulator id developed. This simulator allows dynamic control of devices. It is based on three main principles

  11. A Radiation Solver for the National Combustion Code

    Science.gov (United States)

    Sockol, Peter M.

    2015-01-01

    A methodology is given that converts an existing finite volume radiative transfer method that requires input of local absorption coefficients to one that can treat a mixture of combustion gases and compute the coefficients on the fly from the local mixture properties. The Full-spectrum k-distribution method is used to transform the radiative transfer equation (RTE) to an alternate wave number variable, g . The coefficients in the transformed equation are calculated at discrete temperatures and participating species mole fractions that span the values of the problem for each value of g. These results are stored in a table and interpolation is used to find the coefficients at every cell in the field. Finally, the transformed RTE is solved for each g and Gaussian quadrature is used to find the radiant heat flux throughout the field. The present implementation is in an existing cartesian/cylindrical grid radiative transfer code and the local mixture properties are given by a solution of the National Combustion Code (NCC) on the same grid. Based on this work the intention is to apply this method to an existing unstructured grid radiation code which can then be coupled directly to NCC.

  12. Local Reactive Power Control Methods for Overvoltage Prevention of Distributed Solar Inverters in Low-Voltage Grids

    DEFF Research Database (Denmark)

    Demirok, Erhan; Gonzalez, Pablo Casado; Frederiksen, Kenn H. B.

    2011-01-01

    on sensitivity analysis. The sensitivity analysis shows that the same amount of reactive power becomes more effective for grid voltage support if the solar inverter is located at the end of a feeder. Based on this fundamental knowledge, a location-dependent power factor set value can be assigned to each inverter......voltage (LV) grids by means of solar inverters with reactive power control capability. This paper underlines weak points of standard reactive power strategies which are already imposed by certain grid codes, and then, the study introduces a new reactive power control method that is based......, and the grid voltage support can be achieved with less total reactive power consumption. In order to prevent unnecessary reactive power absorption from the grid during admissible voltage range or to increase reactive power contribution from the inverters that are closest to the transformer during grid...

  13. Soil Erosion Estimation Using Grid-based Computation

    Directory of Open Access Journals (Sweden)

    Josef Vlasák

    2005-06-01

    Full Text Available Soil erosion estimation is an important part of a land consolidation process. Universal soil loss equation (USLE was presented by Wischmeier and Smith. USLE computation uses several factors, namely R – rainfall factor, K – soil erodability, L – slope length factor, S – slope gradient factor, C – cropping management factor, and P – erosion control management factor. L and S factors are usually combined to one LS factor – Topographic factor. The single factors are determined from several sources, such as DTM (Digital Terrain Model, BPEJ – soil type map, aerial and satellite images, etc. A conventional approach to the USLE computation, which is widely used in the Czech Republic, is based on the selection of characteristic profiles for which all above-mentioned factors must be determined. The result (G – annual soil loss of such computation is then applied for a whole area (slope of interest. Another approach to the USLE computation uses grids as a main data-structure. A prerequisite for a grid-based USLE computation is that each of the above-mentioned factors exists as a separate grid layer. The crucial step in this computation is a selection of appropriate grid resolution (grid cell size. A large cell size can cause an undesirable precision degradation. Too small cell size can noticeably slow down the whole computation. Provided that the cell size is derived from the source’s precision, the appropriate cell size for the Czech Republic varies from 30m to 50m. In some cases, especially when new surveying was done, grid computations can be performed with higher accuracy, i.e. with a smaller grid cell size. In such case, we have proposed a new method using the two-step computation. The first step computation uses a bigger cell size and is designed to identify higher erosion spots. The second step then uses a smaller cell size but it make the computation only the area identified in the previous step. This decomposition allows a

  14. Development and Implementation of CFD-Informed Models for the Advanced Subchannel Code CTF

    Science.gov (United States)

    Blyth, Taylor S.

    The research described in this PhD thesis contributes to the development of efficient methods for utilization of high-fidelity models and codes to inform low-fidelity models and codes in the area of nuclear reactor core thermal-hydraulics. The objective is to increase the accuracy of predictions of quantities of interests using high-fidelity CFD models while preserving the efficiency of low-fidelity subchannel core calculations. An original methodology named Physics-based Approach for High-to-Low Model Information has been further developed and tested. The overall physical phenomena and corresponding localized effects, which are introduced by the presence of spacer grids in light water reactor (LWR) cores, are dissected in corresponding four building basic processes, and corresponding models are informed using high-fidelity CFD codes. These models are a spacer grid-directed cross-flow model, a grid-enhanced turbulent mixing model, a heat transfer enhancement model, and a spacer grid pressure loss model. The localized CFD-models are developed and tested using the CFD code STAR-CCM+, and the corresponding global model development and testing in sub-channel formulation is performed in the thermal-hydraulic subchannel code CTF. The improved CTF simulations utilize data-files derived from CFD STAR-CCM+ simulation results covering the spacer grid design desired for inclusion in the CTF calculation. The current implementation of these models is examined and possibilities for improvement and further development are suggested. The validation experimental database is extended by including the OECD/NRC PSBT benchmark data. The outcome is an enhanced accuracy of CTF predictions while preserving the computational efficiency of a low-fidelity subchannel code.

  15. Development and Implementation of CFD-Informed Models for the Advanced Subchannel Code CTF

    Energy Technology Data Exchange (ETDEWEB)

    Blyth, Taylor S. [Pennsylvania State Univ., University Park, PA (United States); Avramova, Maria [North Carolina State Univ., Raleigh, NC (United States)

    2017-04-01

    The research described in this PhD thesis contributes to the development of efficient methods for utilization of high-fidelity models and codes to inform low-fidelity models and codes in the area of nuclear reactor core thermal-hydraulics. The objective is to increase the accuracy of predictions of quantities of interests using high-fidelity CFD models while preserving the efficiency of low-fidelity subchannel core calculations. An original methodology named Physics- based Approach for High-to-Low Model Information has been further developed and tested. The overall physical phenomena and corresponding localized effects, which are introduced by the presence of spacer grids in light water reactor (LWR) cores, are dissected in corresponding four building basic processes, and corresponding models are informed using high-fidelity CFD codes. These models are a spacer grid-directed cross-flow model, a grid-enhanced turbulent mixing model, a heat transfer enhancement model, and a spacer grid pressure loss model. The localized CFD-models are developed and tested using the CFD code STAR-CCM+, and the corresponding global model development and testing in sub-channel formulation is performed in the thermal- hydraulic subchannel code CTF. The improved CTF simulations utilize data-files derived from CFD STAR-CCM+ simulation results covering the spacer grid design desired for inclusion in the CTF calculation. The current implementation of these models is examined and possibilities for improvement and further development are suggested. The validation experimental database is extended by including the OECD/NRC PSBT benchmark data. The outcome is an enhanced accuracy of CTF predictions while preserving the computational efficiency of a low-fidelity subchannel code.

  16. Improvement of MARS code reflood model

    International Nuclear Information System (INIS)

    Hwang, Moonkyu; Chung, Bub-Dong

    2011-01-01

    A specifically designed heat transfer model for the reflood process which normally occurs at low flow and low pressure was originally incorporated in the MARS code. The model is essentially identical to that of the RELAP5/MOD3.3 code. The model, however, is known to have under-estimated the peak cladding temperature (PCT) with earlier turn-over. In this study, the original MARS code reflood model is improved. Based on the extensive sensitivity studies for both hydraulic and wall heat transfer models, it is found that the dispersed flow film boiling (DFFB) wall heat transfer is the most influential process determining the PCT, whereas the interfacial drag model most affects the quenching time through the liquid carryover phenomenon. The model proposed by Bajorek and Young is incorporated for the DFFB wall heat transfer. Both space grid and droplet enhancement models are incorporated. Inverted annular film boiling (IAFB) is modeled by using the original PSI model of the code. The flow transition between the DFFB and IABF, is modeled using the TRACE code interpolation. A gas velocity threshold is also added to limit the top-down quenching effect. Assessment calculations are performed for the original and modified MARS codes for the Flecht-Seaset test and RBHT test. Improvements are observed in terms of the PCT and quenching time predictions in the Flecht-Seaset assessment. In case of the RBHT assessment, the improvement over the original MARS code is found marginal. A space grid effect, however, is clearly seen from the modified version of the MARS code. (author)

  17. A Subdivision Method to Unify the Existing Latitude and Longitude Grids

    Directory of Open Access Journals (Sweden)

    Chengqi Cheng

    2016-09-01

    Full Text Available As research on large regions of earth progresses, many geographical subdivision grids have been established for various spatial applications by different industries and disciplines. However, there is no clear relationship between the different grids and no consistent spatial reference grid that allows for information exchange and comprehensive application. Sharing and exchange of data across departments and applications are still at a bottleneck. It would represent a significant step forward to build a new grid model that is inclusive of or compatible with most of the existing geodesic grids and that could support consolidation and exchange within existing data services. This study designs a new geographical coordinate global subdividing grid with one dimension integer coding on a 2n tree (GeoSOT that has 2n coordinate subdivision characteristics (global longitude and latitude subdivision and can form integer hierarchies at degree, minute, and second levels. This grid has the multi-dimensional quadtree hierarchical characteristics of a digital earth grid, but also provides good consistency with applied grids, such as those used in mapping, meteorology, oceanography and national geographical, and three-dimensional digital earth grids. No other existing grid codes possess these characteristics.

  18. Verification of the three-dimensional tetrahedral grid S{sub N} code THOR

    Energy Technology Data Exchange (ETDEWEB)

    Schunert, S. [Department of Nuclear Engineering, North Carolina State University (United States); Ferrer, R. [Studsvik Scandpower, Idaho Falls, ID (United States); Azmy, Y. [Department of Nuclear Engineering, North Carolina State University (United States)

    2013-07-01

    In this work current capabilities implemented in the novel, arbitrary-order, tetrahedral-grid short characteristics S{sub N} radiation transport code THOR are verified based on four benchmark problems: (1) A one-group Method of Manufactured Solution (MMS) problem on a cuboidal domain, (2) an infinite medium eigenvalue problem with up-scattering, (3) a homogeneous torus and (4) a bare cube eigenvalue problem with anisotropic scattering up to order three. The first benchmark problem exercises the various spatial discretization options available in THOR: The short characteristics method in conjunction with polynomial expansions of the source and face fluxes either using the complete or Lagrange family of arbitrary orders. Using the numerical solution's order of convergence test in the framework of a mesh refinement study, correct implementation of a selection of spatial expansion orders is demonstrated for two meshes with tetrahedral aspect ratios close to unity and 50. The second benchmark problem exercises the implementation of angular fluxes on reflective boundary faces that are implicit within a mesh sweep, and up-scattering. The third benchmark problem comprises cyclic dependencies within the mesh sweep thus exercising the algorithm devised for 'breaking' the cyclic dependencies. Finally, the fourth benchmark problem, a simple bare cube, is used to test correct implementation of the anisotropic scattering capability. For all test problems THOR obtains solutions that converge to the reference/exact solution with the expected rate thereby contributing to our confidence in the correctness of its tested features in the present implementation. (authors)

  19. MAGNETOHYDRODYNAMIC MODELING OF SOLAR SYSTEM PROCESSES ON GEODESIC GRIDS

    Energy Technology Data Exchange (ETDEWEB)

    Florinski, V. [Department of Physics, University of Alabama, Huntsville, AL 35899 (United States); Guo, X. [Center for Space Plasma and Aeronomic Research, University of Alabama, Huntsville, AL 35899 (United States); Balsara, D. S.; Meyer, C. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States)

    2013-04-01

    This report describes a new magnetohydrodynamic numerical model based on a hexagonal spherical geodesic grid. The model is designed to simulate astrophysical flows of partially ionized plasmas around a central compact object, such as a star or a planet with a magnetic field. The geodesic grid, produced by a recursive subdivision of a base platonic solid (an icosahedron), is free from control volume singularities inherent in spherical polar grids. Multiple populations of plasma and neutral particles, coupled via charge-exchange interactions, can be simulated simultaneously with this model. Our numerical scheme uses piecewise linear reconstruction on a surface of a sphere in a local two-dimensional 'Cartesian' frame. The code employs Haarten-Lax-van-Leer-type approximate Riemann solvers and includes facilities to control the divergence of the magnetic field and maintain pressure positivity. Several test solutions are discussed, including a problem of an interaction between the solar wind and the local interstellar medium, and a simulation of Earth's magnetosphere.

  20. MAGNETOHYDRODYNAMIC MODELING OF SOLAR SYSTEM PROCESSES ON GEODESIC GRIDS

    International Nuclear Information System (INIS)

    Florinski, V.; Guo, X.; Balsara, D. S.; Meyer, C.

    2013-01-01

    This report describes a new magnetohydrodynamic numerical model based on a hexagonal spherical geodesic grid. The model is designed to simulate astrophysical flows of partially ionized plasmas around a central compact object, such as a star or a planet with a magnetic field. The geodesic grid, produced by a recursive subdivision of a base platonic solid (an icosahedron), is free from control volume singularities inherent in spherical polar grids. Multiple populations of plasma and neutral particles, coupled via charge-exchange interactions, can be simulated simultaneously with this model. Our numerical scheme uses piecewise linear reconstruction on a surface of a sphere in a local two-dimensional 'Cartesian' frame. The code employs Haarten-Lax-van-Leer-type approximate Riemann solvers and includes facilities to control the divergence of the magnetic field and maintain pressure positivity. Several test solutions are discussed, including a problem of an interaction between the solar wind and the local interstellar medium, and a simulation of Earth's magnetosphere.

  1. Real Time Load Optimisation of Cable Based Transmission Grids

    DEFF Research Database (Denmark)

    Olsen, Rasmus Schmidt; Holbøll, Joachim; Guðmundsdottir, Unnur Stella

    2011-01-01

    Energinet.dk has launched an investigation of dynamic current ratings of cable based transmission grids, where both internal and external parameters are variables. The first topic was to investigate state of the art within calculating the current carrying capacity (ampacity or loadability......) of cables embedded in larger cable systems. Some recently published research has been concerned with dynamic loadability, but such researches are based on many assumptions. It is shown in the paper, that only limited research has been concerned with larger cable grids, and no remarkable work could been...

  2. MICROARRAY IMAGE GRIDDING USING GRID LINE REFINEMENT TECHNIQUE

    Directory of Open Access Journals (Sweden)

    V.G. Biju

    2015-05-01

    Full Text Available An important stage in microarray image analysis is gridding. Microarray image gridding is done to locate sub arrays in a microarray image and find co-ordinates of spots within each sub array. For accurate identification of spots, most of the proposed gridding methods require human intervention. In this paper a fully automatic gridding method which enhances spot intensity in the preprocessing step as per a histogram based threshold method is used. The gridding step finds co-ordinates of spots from horizontal and vertical profile of the image. To correct errors due to the grid line placement, a grid line refinement technique is proposed. The algorithm is applied on different image databases and results are compared based on spot detection accuracy and time. An average spot detection accuracy of 95.06% depicts the proposed method’s flexibility and accuracy in finding the spot co-ordinates for different database images.

  3. Development of parallel Fokker-Planck code ALLAp

    International Nuclear Information System (INIS)

    Batishcheva, A.A.; Sigmar, D.J.; Koniges, A.E.

    1996-01-01

    We report on our ongoing development of the 3D Fokker-Planck code ALLA for a highly collisional scrape-off-layer (SOL) plasma. A SOL with strong gradients of density and temperature in the spatial dimension is modeled. Our method is based on a 3-D adaptive grid (in space, magnitude of the velocity, and cosine of the pitch angle) and a second order conservative scheme. Note that the grid size is typically 100 x 257 x 65 nodes. It was shown in our previous work that only these capabilities make it possible to benchmark a 3D code against a spatially-dependent self-similar solution of a kinetic equation with the Landau collision term. In the present work we show results of a more precise benchmarking against the exact solutions of the kinetic equation using a new parallel code ALLAp with an improved method of parallelization and a modified boundary condition at the plasma edge. We also report first results from the code parallelization using Message Passing Interface for a Massively Parallel CRI T3D platform. We evaluate the ALLAp code performance versus the number of T3D processors used and compare its efficiency against a Work/Data Sharing parallelization scheme and a workstation version

  4. Demonstration of Automatically-Generated Adjoint Code for Use in Aerodynamic Shape Optimization

    Science.gov (United States)

    Green, Lawrence; Carle, Alan; Fagan, Mike

    1999-01-01

    Gradient-based optimization requires accurate derivatives of the objective function and constraints. These gradients may have previously been obtained by manual differentiation of analysis codes, symbolic manipulators, finite-difference approximations, or existing automatic differentiation (AD) tools such as ADIFOR (Automatic Differentiation in FORTRAN). Each of these methods has certain deficiencies, particularly when applied to complex, coupled analyses with many design variables. Recently, a new AD tool called ADJIFOR (Automatic Adjoint Generation in FORTRAN), based upon ADIFOR, was developed and demonstrated. Whereas ADIFOR implements forward-mode (direct) differentiation throughout an analysis program to obtain exact derivatives via the chain rule of calculus, ADJIFOR implements the reverse-mode counterpart of the chain rule to obtain exact adjoint form derivatives from FORTRAN code. Automatically-generated adjoint versions of the widely-used CFL3D computational fluid dynamics (CFD) code and an algebraic wing grid generation code were obtained with just a few hours processing time using the ADJIFOR tool. The codes were verified for accuracy and were shown to compute the exact gradient of the wing lift-to-drag ratio, with respect to any number of shape parameters, in about the time required for 7 to 20 function evaluations. The codes have now been executed on various computers with typical memory and disk space for problems with up to 129 x 65 x 33 grid points, and for hundreds to thousands of independent variables. These adjoint codes are now used in a gradient-based aerodynamic shape optimization problem for a swept, tapered wing. For each design iteration, the optimization package constructs an approximate, linear optimization problem, based upon the current objective function, constraints, and gradient values. The optimizer subroutines are called within a design loop employing the approximate linear problem until an optimum shape is found, the design loop

  5. The more the merrier: grid based modelling of Kepler dwarfs with 5-dimensional stellar grids

    Directory of Open Access Journals (Sweden)

    Serenelli Aldo

    2017-01-01

    Full Text Available We present preliminary results of our grid based modelling (GBM of the dwarf/subgiant sample of stars observed with Kepler including global asteroseismic parameters. GBM analysis in this work is based on a large grid of stellar models that is characterized by five independent parameters: model mass and age, initial metallicity (Zini, initial helium (Yini, and mixing length parameter (αMLT. Using this grid relaxes assumptions used in all previous GBM work where the initial composition is determined by a single parameter and that αMLT is fixed to a solar-calibrated value. The new grid allows us to study, for example, the impact of different galactic chemical enrichment models on the determination of stellar parameters such as mass radius and age. Also, it allows to include new results from stellar atmosphere models on αMLT in the GBM analysis in a simple manner. Alternatively, it can be tested if global asteroseismology is a useful tool to constraint our ignorance on quantities such as Yini and αMLT. Initial findings show that mass determination is robust with respect to freedom in the latter quantities, with a 4.4% maximum deviation for extreme assumptions regarding prior information on Yini – Zini relations and aMLT. On the other hand, tests carried out so far seem to indicate that global seismology does not have much power to constrain Yini – Zni relations of αMLT values without resourcing to additional information.

  6. Disturbance estimator based predictive current control of grid-connected inverters

    OpenAIRE

    Al-Khafaji, Ahmed Samawi Ghthwan

    2013-01-01

    ABSTRACT: The work presented in my thesis considers one of the modern discrete-time control approaches based on digital signal processing methods, that have been developed to improve the performance control of grid-connected three-phase inverters. Disturbance estimator based predictive current control of grid-connected inverters is proposed. For inverter modeling with respect to the design of current controllers, we choose the d-q synchronous reference frame to make it easier to understand an...

  7. SLGRID: spectral synthesis software in the grid

    Science.gov (United States)

    Sabater, J.; Sánchez, S.; Verdes-Montenegro, L.

    2011-11-01

    SLGRID (http://www.e-ciencia.es/wiki/index.php/Slgrid) is a pilot project proposed by the e-Science Initiative of Andalusia (eCA) and supported by the Spanish e-Science Network in the frame of the European Grid Initiative (EGI). The aim of the project was to adapt the spectral synthesis software Starlight (Cid-Fernandes et al. 2005) to the Grid infrastructure. Starlight is used to estimate the underlying stellar populations (their ages and metallicities) using an optical spectrum, hence, it is possible to obtain a clean nebular spectrum that can be used for the diagnostic of the presence of an Active Galactic Nucleus (Sabater et al. 2008, 2009). The typical serial execution of the code for big samples of galaxies made it ideal to be integrated into the Grid. We obtain an improvement on the computational time of order N, being N the number of nodes available in the Grid. In a real case we obtained our results in 3 hours with SLGRID instead of the 60 days spent using Starlight in a PC. The code has already been ported to the Grid. The first tests were made within the e-CA infrastrusture and, later, itwas tested and improved with the colaboration of the CETA-CIEMAT. The SLGRID project has been recently renewed. In a future it is planned to adapt the code for the reduction of data from Integral Field Units where each dataset is composed of hundreds of spectra. Electronic version of the poster at http://www.iaa.es/~jsm/SEA2010

  8. QC-LDPC code-based cryptography

    CERN Document Server

    Baldi, Marco

    2014-01-01

    This book describes the fundamentals of cryptographic primitives based on quasi-cyclic low-density parity-check (QC-LDPC) codes, with a special focus on the use of these codes in public-key cryptosystems derived from the McEliece and Niederreiter schemes. In the first part of the book, the main characteristics of QC-LDPC codes are reviewed, and several techniques for their design are presented, while tools for assessing the error correction performance of these codes are also described. Some families of QC-LDPC codes that are best suited for use in cryptography are also presented. The second part of the book focuses on the McEliece and Niederreiter cryptosystems, both in their original forms and in some subsequent variants. The applicability of QC-LDPC codes in these frameworks is investigated by means of theoretical analyses and numerical tools, in order to assess their benefits and drawbacks in terms of system efficiency and security. Several examples of QC-LDPC code-based public key cryptosystems are prese...

  9. A GPU-based incompressible Navier-Stokes solver on moving overset grids

    Science.gov (United States)

    Chandar, Dominic D. J.; Sitaraman, Jayanarayanan; Mavriplis, Dimitri J.

    2013-07-01

    In pursuit of obtaining high fidelity solutions to the fluid flow equations in a short span of time, graphics processing units (GPUs) which were originally intended for gaming applications are currently being used to accelerate computational fluid dynamics (CFD) codes. With a high peak throughput of about 1 TFLOPS on a PC, GPUs seem to be favourable for many high-resolution computations. One such computation that involves a lot of number crunching is computing time accurate flow solutions past moving bodies. The aim of the present paper is thus to discuss the development of a flow solver on unstructured and overset grids and its implementation on GPUs. In its present form, the flow solver solves the incompressible fluid flow equations on unstructured/hybrid/overset grids using a fully implicit projection method. The resulting discretised equations are solved using a matrix-free Krylov solver using several GPU kernels such as gradient, Laplacian and reduction. Some of the simple arithmetic vector calculations are implemented using the CU++: An Object Oriented Framework for Computational Fluid Dynamics Applications using Graphics Processing Units, Journal of Supercomputing, 2013, doi:10.1007/s11227-013-0985-9 approach where GPU kernels are automatically generated at compile time. Results are presented for two- and three-dimensional computations on static and moving grids.

  10. A Parallel Multiblock Structured Grid Method with Automated Interblocked Unstructured Grids for Chemically Reacting Flows

    Science.gov (United States)

    Spiegel, Seth Christian

    An automated method for using unstructured grids to patch non- C0 interfaces between structured blocks has been developed in conjunction with a finite-volume method for solving chemically reacting flows on unstructured grids. Although the standalone unstructured solver, FVFLO-NCSU, is capable of resolving flows for high-speed aeropropulsion devices with complex geometries, unstructured-mesh algorithms are inherently inefficient when compared to their structured counterparts. However, the advantages of structured algorithms in developing a flow solution in a timely manner can be negated by the amount of time required to develop a mesh for complex geometries. The global domain can be split up into numerous smaller blocks during the grid-generation process to alleviate some of the difficulties in creating these complex meshes. An even greater abatement can be found by allowing the nodes on abutting block interfaces to be nonmatching or non-C 0 continuous. One code capable of solving chemically reacting flows on these multiblock grids is VULCAN, which uses a nonconservative approach for patching non-C0 block interfaces. The developed automated unstructured-grid patching algorithm has been installed within VULCAN to provide it the capability of a fully conservative approach for patching non-C0 block interfaces. Additionally, the FVFLO-NCSU solver algorithms have been deeply intertwined with the VULCAN source code to solve chemically reacting flows on these unstructured patches. Finally, the CGNS software library was added to the VULCAN postprocessor so structured and unstructured data can be stored in a single compact file. This final upgrade to VULCAN has been successfully installed and verified using test cases with particular interest towards those involving grids with non- C0 block interfaces.

  11. The architecture of a virtual grid GIS server

    Science.gov (United States)

    Wu, Pengfei; Fang, Yu; Chen, Bin; Wu, Xi; Tian, Xiaoting

    2008-10-01

    The grid computing technology provides the service oriented architecture for distributed applications. The virtual Grid GIS server is the distributed and interoperable enterprise application GIS architecture running in the grid environment, which integrates heterogeneous GIS platforms. All sorts of legacy GIS platforms join the grid as members of GIS virtual organization. Based on Microkernel we design the ESB and portal GIS service layer, which compose Microkernel GIS. Through web portals, portal GIS services and mediation of service bus, following the principle of SoC, we separate business logic from implementing logic. Microkernel GIS greatly reduces the coupling degree between applications and GIS platforms. The enterprise applications are independent of certain GIS platforms, and making the application developers to pay attention to the business logic. Via configuration and orchestration of a set of fine-grained services, the system creates GIS Business, which acts as a whole WebGIS request when activated. In this way, the system satisfies a business workflow directly and simply, with little or no new code.

  12. Stability Augmentation of a Grid-Connected Wind Farm by Fuzzy-Logic-Controlled DFIG-Based Wind Turbines

    Directory of Open Access Journals (Sweden)

    Md. Rifat Hazari

    2017-12-01

    Full Text Available Wind farm (WF grid codes require wind generators to have low voltage ride through (LVRT capability, which means that normal power production should be resumed quickly once the nominal grid voltage has been recovered. However, WFs with fixed-speed wind turbines with squirrel cage induction generators (FSWT-SCIGs have failed to fulfill the LVRT requirement, which has a significant impact on power system stability. On the other hand, variable-speed wind turbines with doubly fed induction generators (VSWT-DFIGs have sufficient LVRT augmentation capability and can control the active and reactive power delivered to the grid. However, the DFIG is more expensive than the SCIG due to its AC/DC/AC converter. Therefore, the combined use of SCIGs and DFIGs in a WF could be an effective solution. The design of the rotor-side converter (RSC controller is crucial because the RSC controller contributes to the system stability. The cascaded control strategy based on four conventional PI controllers is widely used to control the RSC of the DFIG, which can inject only a small amount of reactive power during fault conditions. Therefore, the conventional strategy can stabilize the lower rating of the SCIG. In the present paper, a new control strategy based on fuzzy logic is proposed in the RSC controller of the DFIG in order to enhance the LVRT capability of the SCIG in a WF. The proposed fuzzy logic controller (FLC is used to control the reactive power delivered to the grid during fault conditions. Moreover, reactive power injection can be increased in the proposed control strategy. Extensive simulations executed in the PSCAD/EMTDC environment for both the proposed and conventional PI controllers of the RSC of the DFIG reveal that the proposed control strategy can stabilize the higher rating of the SCIG.

  13. Grid-friendly wind power systems based on the synchronverter technology

    International Nuclear Information System (INIS)

    Zhong, Qing-Chang; Ma, Zhenyu; Ming, Wen-Long; Konstantopoulos, George C.

    2015-01-01

    Highlights: • A grid-friendly wind power system that uses the synchronverter technology is proposed. • Both the rotor-side and the grid-side converters act as synchronverters. • The complete generator–motor–generator system improves the performance under grid faults. • Real-time digital simulation results verify the effectiveness of the proposed method. - Abstract: Back-to-back PWM converters are becoming a realistic alternative to conventional converters in high-power wind power applications. In this paper, a control strategy based on the synchronverter technology is proposed for back-to-back PWM converters. Both converters are run as synchronverters, which are mathematically equivalent to the conventional synchronous generators. The rotor-side converter is responsible for maintaining the DC link voltage and the grid-side converter is responsible for the maximum power point tracking (MPPT). As the two converters are operated using the synchronverter technology, the formed wind power system becomes more friendly to the grid. Extensive real-time digital simulation results are presented to verify the effectiveness of the proposed method under normal operation and grid-fault scenarios

  14. The extended RBAC model based on grid computing

    Institute of Scientific and Technical Information of China (English)

    CHEN Jian-gang; WANG Ru-chuan; WANG Hai-yan

    2006-01-01

    This article proposes the extended role-based access control (RBAC) model for solving dynamic and multidomain problems in grid computing, The formulated description of the model has been provided. The introduction of context and the mapping relations of context-to-role and context-to-permission help the model adapt to dynamic property in grid environment.The multidomain role inheritance relation by the authorization agent service realizes the multidomain authorization amongst the autonomy domain. A function has been proposed for solving the role inheritance conflict during the establishment of the multidomain role inheritance relation.

  15. Smart Energy Management and Control for Fuel Cell Based Micro-Grid Connected Neighborhoods

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Mohammad S. Alam

    2006-03-15

    Fuel cell power generation promises to be an efficient, pollution-free, reliable power source in both large scale and small scale, remote applications. DOE formed the Solid State Energy Conversion Alliance with the intention of breaking one of the last barriers remaining for cost effective fuel cell power generation. The Alliance’s goal is to produce a core solid-state fuel cell module at a cost of no more than $400 per kilowatt and ready for commercial application by 2010. With their inherently high, 60-70% conversion efficiencies, significantly reduced carbon dioxide emissions, and negligible emissions of other pollutants, fuel cells will be the obvious choice for a broad variety of commercial and residential applications when their cost effectiveness is improved. In a research program funded by the Department of Energy, the research team has been investigating smart fuel cell-operated residential micro-grid communities. This research has focused on using smart control systems in conjunction with fuel cell power plants, with the goal to reduce energy consumption, reduce demand peaks and still meet the energy requirements of any household in a micro-grid community environment. In Phases I and II, a SEMaC was developed and extended to a micro-grid community. In addition, an optimal configuration was determined for a single fuel cell power plant supplying power to a ten-home micro-grid community. In Phase III, the plan is to expand this work to fuel cell based micro-grid connected neighborhoods (mini-grid). The economic implications of hydrogen cogeneration will be investigated. These efforts are consistent with DOE’s mission to decentralize domestic electric power generation and to accelerate the onset of the hydrogen economy. A major challenge facing the routine implementation and use of a fuel cell based mini-grid is the varying electrical demand of the individual micro-grids, and, therefore, analyzing these issues is vital. Efforts are needed to determine

  16. SQoS based Planning using 4-regular Grid for Optical Fiber Metworks

    DEFF Research Database (Denmark)

    Riaz, Muhammad Tahir; Pedersen, Jens Myrup; Madsen, Ole Brun

    optical fiber based network infrastructures. In the first step of SQoS based planning, this paper describes how 4-regular Grid structures can be implemented in the physical level of optical fiber network infrastructures. A systematic approach for implementing the Grid structure is presented. We used...

  17. SQoS based Planning using 4-regular Grid for Optical Fiber Networks

    DEFF Research Database (Denmark)

    Riaz, Muhammad Tahir; Pedersen, Jens Myrup; Madsen, Ole Brun

    2005-01-01

    optical fiber based network infrastructures. In the first step of SQoS based planning, this paper describes how 4-regular Grid structures can be implemented in the physical level of optical fiber network infrastructures. A systematic approach for implementing the Grid structure is presented. We used...

  18. Program EAGLE User’s Manual. Volume 3. Grid Generation Code

    Science.gov (United States)

    1988-09-01

    15 1. ompps.te Grid Structure ..... .. .................. . 15 2. Block Interfaces ......... ...................... . 18 3. Fundmental ...in principle it is possible to establish a correspondence between any physical region and a single empty rectangular block for general three...differences. Since this second surrounding layer is not involved in the grid generation, no further account will be taken of its presence in the present

  19. Efficient identification of opportunities for Distributed Generation based on Smart Grid Technology

    DEFF Research Database (Denmark)

    Mutule, Anna; Obushevs, Artjoms; Lvov, Aleksandr

    2013-01-01

    The paper presents the main goals and achievements of the Smart Grids ERA-NET project named “Efficient identification of opportunities for Distributed Generation based on Smart Grid Technology (SmartGen)” during the second stage of project implementation. A description of Smart Grid Technology (S......) models developed within the framework of the project is given. The performed study cases where the SGT-models were implemented to analyze the impact of the electrical grid are discussed....

  20. A methodology toward manufacturing grid-based virtual enterprise operation platform

    Science.gov (United States)

    Tan, Wenan; Xu, Yicheng; Xu, Wei; Xu, Lida; Zhao, Xianhua; Wang, Li; Fu, Liuliu

    2010-08-01

    Virtual enterprises (VEs) have become one of main types of organisations in the manufacturing sector through which the consortium companies organise their manufacturing activities. To be competitive, a VE relies on the complementary core competences among members through resource sharing and agile manufacturing capacity. Manufacturing grid (M-Grid) is a platform in which the production resources can be shared. In this article, an M-Grid-based VE operation platform (MGVEOP) is presented as it enables the sharing of production resources among geographically distributed enterprises. The performance management system of the MGVEOP is based on the balanced scorecard and has the capacity of self-learning. The study shows that a MGVEOP can make a semi-automated process possible for a VE, and the proposed MGVEOP is efficient and agile.

  1. Deploying web-based visual exploration tools on the grid

    Energy Technology Data Exchange (ETDEWEB)

    Jankun-Kelly, T.J.; Kreylos, Oliver; Shalf, John; Ma, Kwan-Liu; Hamann, Bernd; Joy, Kenneth; Bethel, E. Wes

    2002-02-01

    We discuss a web-based portal for the exploration, encapsulation, and dissemination of visualization results over the Grid. This portal integrates three components: an interface client for structured visualization exploration, a visualization web application to manage the generation and capture of the visualization results, and a centralized portal application server to access and manage grid resources. We demonstrate the usefulness of the developed system using an example for Adaptive Mesh Refinement (AMR) data visualization.

  2. OPNET/Simulink Based Testbed for Disturbance Detection in the Smart Grid

    Energy Technology Data Exchange (ETDEWEB)

    Sadi, Mohammad A. H. [University of Memphis; Dasgupta, Dipankar [ORNL; Ali, Mohammad Hassan [University of Memphis; Abercrombie, Robert K [ORNL

    2015-01-01

    The important backbone of the smart grid is the cyber/information infrastructure, which is primarily used to communicate with different grid components. A smart grid is a complex cyber physical system containing a numerous and variety number of sources, devices, controllers and loads. Therefore, the smart grid is vulnerable to grid related disturbances. For such dynamic system, disturbance and intrusion detection is a paramount issue. This paper presents a Simulink and Opnet based co-simulated platform to carry out a cyber-intrusion in cyber network for modern power systems and the smart grid. The IEEE 30 bus power system model is used to demonstrate the effectiveness of the simulated testbed. The experiments were performed by disturbing the circuit breakers reclosing time through a cyber-attack. Different disturbance situations in the considered test system are considered and the results indicate the effectiveness of the proposed co-simulated scheme.

  3. Mini-Grids for the Base of the Pyramid Market: A Critical Review

    Directory of Open Access Journals (Sweden)

    Subhes C. Bhattacharyya

    2018-04-01

    Full Text Available The lack of access to electricity of more than 1.1 billion people around the world remains a major developmental challenge and Goal 7 of the Sustainable Development Goals (SDG as well as Sustainable Energy for All (SE4ALL have set a target of universal electrification by 2030. Various studies have identified mini-grid-based electrification as a possible solution. There is a growing body of literature available now that has explored the feasibility, practical application and policy interventions required to support mini-grids. Through a review of available literature, this paper explores whether mini-grids can be a solution for the base of the pyramid (BoP market and the challenges faced in deploying mini-grids in such markets. Interventions to support the mini-grid deployment are also discussed. The paper finds that the mini-grids are targeting the BoP market but the business is not attractive in profitability terms and requires financial support. Lack of regulatory clarity and non-coordinated policies affect the financial viability of projects, which requires careful support. Mini-grid electrification has hardly been embedded in rural development agenda and hence they have not contributed significantly to livelihood generation. Careful realignment of policies, regulatory frameworks and support systems can better support mini-grid deployment in developing countries.

  4. Simulation of a flexible wind turbine response to a grid fault

    DEFF Research Database (Denmark)

    Hansen, Anca Daniela; Cutululis, Nicolaos Antonio; Sørensen, Poul Ejnar

    2007-01-01

    The purpose of this work is to illustrate the impact of a grid fault on the mechanical loads of a wind turbine. Grid faults generate transients in the generator electromagnetic torque, which are propagated in the wind turbine, stressing its mechanical components. Grid faults are normally simulated...... in power system simulation tools applying simplified mechanical models of the drive train. This paper presents simulations of the wind turbine load response to grid faults with an advanced aeroelastic computer code (HAWC2). The core of this code is an advanced model for the flexible structure of the wind...... turbines, taking the flexibility of the tower, blades and other components of the wind turbines into account. The effect of a grid fault on the wind turbine flexible structure is assessed for a typical fixed speed wind turbine, equipped with an induction generator....

  5. Cost on Reliability and Production Loss for Power Converters in the Doubly Fed Induction Generator to Support Modern Grid Codes

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede; Lau, Mogens

    2016-01-01

    As wind farms are normally located in remote areas, many grid codes have been issued especially related to the reactive power support. Although the Doubly-Fed Induction Generator (DFIG) based power converter is able to control the active power and reactive power independently, the effects...... of providing reactive power on the lifetime of the power converter and the cost-of-energy of the whole system are seldom evaluated, even though it is an important topic. In this paper, the loss models of the DFIG system are established at various conditions of the reactive power injection. If the mission...... profile is taken into account, the lifespan of the power semiconductors as well as the cost of the reactive power can be calculated. It is concluded that an over-excited reactive power injection significantly reduces the power converter lifetime, only 1/4 of the case that there is no reactive power...

  6. Grid faults' impact on wind turbine structural loads

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, A.D.; Cutululis, N.A.; Soerensen, P.; Larsen, T.J. [Risoe National Lab., DTU, Wind Energy Dept. (Denmark); Iov, F.

    2007-11-15

    The objective of this work is to illustrate the impact of the grid faults on the wind turbine structural loads. Grid faults are typically in detailed power system simulation tools, which by applying simplified mechanical models, are not able to provide a throughout insight on the structural loads caused by sudden disturbances on the grid. On the other hand, structural loads of the wind turbine are typically assessed in advanced aeroelastic computer codes, which by applying simplified electrical models do not provide detailed electrical insight. This paper presents a simulation strategy, where the focus is on how to access a proper combination of two complementary simulation tools, such as the advanced aeroelastic computer code HAWC2 and the detailed power system simulation tool DIgSILENT, in order to provide a whole overview of both the structural and the electrical behaviour of the wind turbine during grid faults. The effect of a grid fault on the wind turbine flexible structure is assessed for a typical fixed speed wind turbine, equipped with an induction generator. (au)

  7. Numerical study of a gridded E-GUN with a very small cathode-grid distance (150 {mu}m) using EGN2

    Energy Technology Data Exchange (ETDEWEB)

    Ronsivalle, C. [ENEA, Centro Ricerche Frascati, Rome (Italy). Dip. Innovazione

    1997-01-01

    A numerical study of a triode gun with a very small cathode-grid distance (150 {mu}m) which allows to evaluate with great accuracy the effect of the grid and of the temperature on the final beam emittance is presented. The simulation uses a modified version of the bidimensional code EGUN for PC that simulates the grid with a set of concentric rings and allows to define several regions of different mesh size, providing the way to connect results between adjacent regions. The calculation procedure is described in detail together with the results of the simulation for different values of the grid potential.

  8. Agent-based Decentralization of Applications in Distributed Smart Grid Systems

    DEFF Research Database (Denmark)

    Kienesberger, Georg; Xypolytou, Evangelia; Marchgraber, Jurgen

    2015-01-01

    systems (DMACS) and aims to give an overview on the different requirements and challenges on the way from current centralized control systems to DMACS. Therefore, different ICT scenarios and MAS topologies are employed to discuss the decentralization of three exemplary smart grid applications: voltage......Smart grid technology promises to prepare today’s power systems for the challenges of the future by extensive integration of information and communication technology (ICT). One key aspect is the control paradigm which will have to be shifted from completely centralized control systems to more...... dezentralized concepts in order to adapt to the distributed nature of smart grids. Multi-agent systems (MAS) are a very promising approach for designing distributed, decentralized systems, naturally also in the field of smart grids. This work introduces the notion of decentralized multi-agent-based control...

  9. AMP: a science-driven web-based application for the TeraGrid

    Science.gov (United States)

    Woitaszek, M.; Metcalfe, T.; Shorrock, I.

    The Asteroseismic Modeling Portal (AMP) provides a web-based interface for astronomers to run and view simulations that derive the properties of Sun-like stars from observations of their pulsation frequencies. In this paper, we describe the architecture and implementation of AMP, highlighting the lightweight design principles and tools used to produce a functional fully-custom web-based science application in less than a year. Targeted as a TeraGrid science gateway, AMP's architecture and implementation are intended to simplify its orchestration of TeraGrid computational resources. AMP's web-based interface was developed as a traditional standalone database-backed web application using the Python-based Django web development framework, allowing us to leverage the Django framework's capabilities while cleanly separating the user interface development from the grid interface development. We have found this combination of tools flexible and effective for rapid gateway development and deployment.

  10. Deployment of a Grid-based Medical Imaging Application

    CERN Document Server

    Amendolia, S R; Frate, C; Gálvez, J; Hassan, W; Hauer, T; Manset, D; McClatchey, R; Odeh, M; Rogulin, D; Solomonides, T; Warren, R

    2005-01-01

    The MammoGrid project has deployed its Service-Oriented Architecture (SOA)-based Grid application in a real environment comprising actual participating hospitals. The resultant setup is currently being exploited to conduct rigorous in-house tests in the first phase before handing over the setup to the actual clinicians to get their feedback. This paper elaborates the deployment details and the experiences acquired during this phase of the project. Finally the strategy regarding migration to an upcoming middleware from EGEE project will be described. This paper concludes by highlighting some of the potential areas of future work.

  11. Single-Phase LLCL-Filter-based Grid-Tied Inverter with Low-Pass Filter Based Capacitor Current Feedback Active damper

    DEFF Research Database (Denmark)

    Liu, Yuan; Wu, Weimin; Li, Yun

    2016-01-01

    The capacitor-current-feedback active damping method is attractive for high-order-filter-based high power grid-tied inverter when the grid impedance varies within a wide range. In order to improve the system control bandwidth and attenuate the high order grid background harmonics by using the quasi....... In this paper, a low pass filter is proposed to be inserted in the capacitor current feedback loop op LLCL-filter based grid-tied inverter together with a digital proportional and differential compensator. The detailed theoretical analysis is given. For verification, simulations on a 2kW/220V/10kHz LLCL...

  12. The GridSite Web/Grid security system

    International Nuclear Information System (INIS)

    McNab, Andrew; Li Yibiao

    2010-01-01

    We present an overview of the current status of the GridSite toolkit, describing the security model for interactive and programmatic uses introduced in the last year. We discuss our experiences of implementing these internal changes and how they and previous rounds of improvements have been prompted by requirements from users and wider security trends in Grids (such as CSRF). Finally, we explain how these have improved the user experience of GridSite-based websites, and wider implications for portals and similar web/grid sites.

  13. Impact of wind power plant reactive current injection during asymmetrical grid faults

    DEFF Research Database (Denmark)

    Göksu, Ömer; Teodorescu, Remus; Bak, Claus Leth

    2013-01-01

    As more renewable energy sources, especially more wind turbines (WTs) are installed in the power system; grid codes for wind power integration are being generated to sustain stable power system operation with non-synchronous generation. Common to most of the grid codes, wind power plants (WPPs...... faults, is investigated, which was not considered in the wind power impact studies before....

  14. Software-Based Challenges of Developing the Future Distribution Grid

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Emma; Kiliccote, Sila; McParland, Charles

    2014-06-01

    distribution grid modeling, and measured data sources are a key missing element . Modeling tools need to be calibrated based on measured grid data to validate their output in varied conditions such as high renewables penetration and rapidly changing topology. In addition, establishing a standardized data modeling format would enable users to transfer data among tools to take advantage of different analysis features. ?

  15. A Costing Analysis for Decision Making Grid Model in Failure-Based Maintenance

    Directory of Open Access Journals (Sweden)

    Burhanuddin M. A.

    2011-01-01

    Full Text Available Background. In current economic downturn, industries have to set good control on production cost, to maintain their profit margin. Maintenance department as an imperative unit in industries should attain all maintenance data, process information instantaneously, and subsequently transform it into a useful decision. Then act on the alternative to reduce production cost. Decision Making Grid model is used to identify strategies for maintenance decision. However, the model has limitation as it consider two factors only, that is, downtime and frequency of failures. We consider third factor, cost, in this study for failure-based maintenance. The objective of this paper is to introduce the formulae to estimate maintenance cost. Methods. Fish bone analysis conducted with Ishikawa model and Decision Making Grid methods are used in this study to reveal some underlying risk factors that delay failure-based maintenance. The goal of the study is to estimate the risk factor that is, repair cost to fit in the Decision Making Grid model. Decision Making grid model consider two variables, frequency of failure and downtime in the analysis. This paper introduces third variable, repair cost for Decision Making Grid model. This approaches give better result to categorize the machines, reduce cost, and boost the earning for the manufacturing plant. Results. We collected data from one of the food processing factories in Malaysia. From our empirical result, Machine C, Machine D, Machine F, and Machine I must be in the Decision Making Grid model even though their frequency of failures and downtime are less than Machine B and Machine N, based on the costing analysis. The case study and experimental results show that the cost analysis in Decision Making Grid model gives more promising strategies in failure-based maintenance. Conclusions. The improvement of Decision Making Grid model for decision analysis with costing analysis is our contribution in this paper for

  16. Cloud feedback studies with a physics grid

    Energy Technology Data Exchange (ETDEWEB)

    Dipankar, Anurag [Max Planck Institute for Meteorology Hamburg; Stevens, Bjorn [Max Planck Institute for Meteorology Hamburg

    2013-02-07

    During this project the investigators implemented a fully parallel version of dual-grid approach in main frame code ICON, implemented a fully conservative first-order interpolation scheme for horizontal remapping, integrated UCLA-LES micro-scale model into ICON to run parallely in selected columns, and did cloud feedback studies on aqua-planet setup to evaluate the classical parameterization on a small domain. The micro-scale model may be run in parallel with the classical parameterization, or it may be run on a "physics grid" independent of the dynamics grid.

  17. An Analysis of Delay-based and Integrator-based Sequence Detectors for Grid-Connected Converters

    DEFF Research Database (Denmark)

    Khazraj, Hesam; Silva, Filipe Miguel Faria da; Bak, Claus Leth

    2017-01-01

    -signal cancellation operators are the main members of the delay-based sequence detectors. The aim of this paper is to provide a theoretical and experimental comparative study between integrator and delay based sequence detectors. The theoretical analysis is conducted based on the small-signal modelling......Detecting and separating positive and negative sequence components of the grid voltage or current is of vital importance in the control of grid-connected power converters, HVDC systems, etc. To this end, several techniques have been proposed in recent years. These techniques can be broadly...... classified into two main classes: The integrator-based techniques and Delay-based techniques. The complex-coefficient filter-based technique, dual second-order generalized integrator-based method, multiple reference frame approach are the main members of the integrator-based sequence detector and the delay...

  18. Grid faults' impact on wind turbine structural loads

    DEFF Research Database (Denmark)

    Hansen, Anca Daniela; Cutululis, Nicolaos Antonio; Iov, F.

    2007-01-01

    The objective of this work is to illustrate the impact of the grid faults on the wind turbine structural loads. Grid faults are typically simulated in detailed power system simulation tools, which by applying simplified mechanical models, are not able to provide a throughout insight...... on the structural loads caused by sudden disturbances on the grid. On the other hand, structural loads of the wind turbine are typically assessed in advanced aerolastic computer codes, which by applying simplified electrical models do not provide detailed electrical insight. This paper presents a simulation...... strategy, where the focus is on how to access a proper combination of two complimentary simulations tools, such as the advanced aeroelastic computer code HAWC2 and the detailed power system simulation tool DIgSILENT, in order to provide a whole overview of both the structural and the electrical behaviour...

  19. Parallel Reservoir Simulations with Sparse Grid Techniques and Applications to Wormhole Propagation

    KAUST Repository

    Wu, Yuanqing

    2015-09-08

    In this work, two topics of reservoir simulations are discussed. The first topic is the two-phase compositional flow simulation in hydrocarbon reservoir. The major obstacle that impedes the applicability of the simulation code is the long run time of the simulation procedure, and thus speeding up the simulation code is necessary. Two means are demonstrated to address the problem: parallelism in physical space and the application of sparse grids in parameter space. The parallel code can gain satisfactory scalability, and the sparse grids can remove the bottleneck of flash calculations. Instead of carrying out the flash calculation in each time step of the simulation, a sparse grid approximation of all possible results of the flash calculation is generated before the simulation. Then the constructed surrogate model is evaluated to approximate the flash calculation results during the simulation. The second topic is the wormhole propagation simulation in carbonate reservoir. In this work, different from the traditional simulation technique relying on the Darcy framework, we propose a new framework called Darcy-Brinkman-Forchheimer framework to simulate wormhole propagation. Furthermore, to process the large quantity of cells in the simulation grid and shorten the long simulation time of the traditional serial code, standard domain-based parallelism is employed, using the Hypre multigrid library. In addition to that, a new technique called “experimenting field approach” to set coefficients in the model equations is introduced. In the 2D dissolution experiments, different configurations of wormholes and a series of properties simulated by both frameworks are compared. We conclude that the numerical results of the DBF framework are more like wormholes and more stable than the Darcy framework, which is a demonstration of the advantages of the DBF framework. The scalability of the parallel code is also evaluated, and good scalability can be achieved. Finally, a mixed

  20. Thermo-mechanical design of the extraction grids for RF negative ion source at HUST

    Energy Technology Data Exchange (ETDEWEB)

    Zuo, Chen; Liu, Kaifeng, E-mail: kfliuhust@hust.edu.cn; Li, Dong; Mei, Zhiyuan; Zhang, Zhe; Chen, Dezhi

    2017-01-15

    Highlights: • An extraction system with cooling channels has been designed for HUST negative ion source. • Corresponding heat loads onto three grids has been used in thermo-mechanical analysis. • The analysis results could be very useful for driving the engineering design. - Abstract: Huazhong University of Science and Technology (HUST) is developing a small radio frequency negative ion source experimental setup to promote research on neutral beam injection ion sources. The extraction system for the negative ion source is the key component to obtain the negative ions. The extraction system is composed of three grids: the plasma grid, the extraction grid and the grounded grid. Each grid is impacted by different heat loads. As the grids have to fulfil specific requirements regarding ion extraction, beam optics, and thermo-mechanical issues, grid cooling systems have been included for ensuring reliable operation. This paper focuses on the thermo-hydraulic and thermo-mechanical design of the grids. Finite element calculations have been carried out to analyse the temperature and deformation of the grids under heat loads using the fluid dynamics code CFX. Based on these results, the cooling circuit design and cooling parameters are optimised to satisfy the grid requirements.

  1. caGrid 1.0: a Grid enterprise architecture for cancer research.

    Science.gov (United States)

    Oster, Scott; Langella, Stephen; Hastings, Shannon; Ervin, David; Madduri, Ravi; Kurc, Tahsin; Siebenlist, Frank; Covitz, Peter; Shanbhag, Krishnakant; Foster, Ian; Saltz, Joel

    2007-10-11

    caGrid is the core Grid architecture of the NCI-sponsored cancer Biomedical Informatics Grid (caBIG) program. The current release, caGrid version 1.0, is developed as the production Grid software infrastructure of caBIG. Based on feedback from adopters of the previous version (caGrid 0.5), it has been significantly enhanced with new features and improvements to existing components. This paper presents an overview of caGrid 1.0, its main components, and enhancements over caGrid 0.5.

  2. The Geographic Information Grid System Based on Mobile Agent

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    We analyze the deficiencies of current application systems, and discuss the key requirements of distributed Geographic Information service (GIS). We construct the distributed GIS on grid platform. Considering the flexibility and efficiency, we integrate the mobile agent technology into the system. We propose a new prototype system, the Geographic Information Grid System (GIGS) based on mobile agent. This system has flexible services and high performance, and improves the sharing of distributed resources. The service strategy of the system and the examples are also presented.

  3. Grid impedance estimation based hybrid islanding detection method for AC microgrids

    DEFF Research Database (Denmark)

    Ghzaiel, Walid; Jebali-Ben Ghorbal, Manel; Slama-Belkhodja, Ilhem

    2017-01-01

    This paper focuses on a hybrid islanding detection algorithm for parallel-inverters-based microgrids. The proposed algorithm is implemented on the unit ensuring the control of the intelligent bypass switch connecting or disconnecting the microgrid from the utility. This method employs a grid...... to avoid interactions with other units. The selected inverter will be the one closest to the controllable distributed generation system or to a healthy grid side in case of meshed microgrid with multiple-grid connections. The detection algorithm is applied to quickly detect the resonance phenomena, so...

  4. Improving mobile robot localization: grid-based approach

    Science.gov (United States)

    Yan, Junchi

    2012-02-01

    Autonomous mobile robots have been widely studied not only as advanced facilities for industrial and daily life automation, but also as a testbed in robotics competitions for extending the frontier of current artificial intelligence. In many of such contests, the robot is supposed to navigate on the ground with a grid layout. Based on this observation, we present a localization error correction method by exploring the geometric feature of the tile patterns. On top of the classical inertia-based positioning, our approach employs three fiber-optic sensors that are assembled under the bottom of the robot, presenting an equilateral triangle layout. The sensor apparatus, together with the proposed supporting algorithm, are designed to detect a line's direction (vertical or horizontal) by monitoring the grid crossing events. As a result, the line coordinate information can be fused to rectify the cumulative localization deviation from inertia positioning. The proposed method is analyzed theoretically in terms of its error bound and also has been implemented and tested on a customary developed two-wheel autonomous mobile robot.

  5. Icing modelling in NSMB with chimera overset grids

    Energy Technology Data Exchange (ETDEWEB)

    Pena, D. [Ècole Polytechnique de Montréal (Canada); ICUBE, Strasbourg University (France); Deloze, T.; Laurendeau, E. [Ècole Polytechnique de Montréal (Canada); Hoarau, Y. [ICUBE, Strasbourg University (France)

    2015-03-10

    In aerospace Engineering, the accurate simulation of ice accretion is a key element to increase flight safety and avoid accidents related to icing effects. The icing code developed in the NSMB solver is based on an Eulerian formulation for droplets tracking, an iterative Messinger model using a modified water runback scheme for ice thickness calculation and mesh deformation to track the ice/air interface through time. The whole process is parallelized with MPI and applied with chimera grids.

  6. Grid-based Simulation of Industrial Thin Film Production

    NARCIS (Netherlands)

    Krzhizhanovskaya, V.V.; Sloot, P.M.A.; Gorbachev, Y.E.

    2005-01-01

    In this article, the authors introduce a Grid-based virtual reactor, a High Level Architecture (HLA)-supported problem-solving environment that allows for detailed numerical study of industrial thin-film production in plasma-enhanced chemical vapor deposition (PECVD) reactors. They briefly describe

  7. Homogeneity and EPR metrics for assessment of regular grids used in CW EPR powder simulations.

    Science.gov (United States)

    Crăciun, Cora

    2014-08-01

    CW EPR powder spectra may be approximated numerically using a spherical grid and a Voronoi tessellation-based cubature. For a given spin system, the quality of simulated EPR spectra depends on the grid type, size, and orientation in the molecular frame. In previous work, the grids used in CW EPR powder simulations have been compared mainly from geometric perspective. However, some grids with similar homogeneity degree generate different quality simulated spectra. This paper evaluates the grids from EPR perspective, by defining two metrics depending on the spin system characteristics and the grid Voronoi tessellation. The first metric determines if the grid points are EPR-centred in their Voronoi cells, based on the resonance magnetic field variations inside these cells. The second metric verifies if the adjacent Voronoi cells of the tessellation are EPR-overlapping, by computing the common range of their resonance magnetic field intervals. Beside a series of well known regular grids, the paper investigates a modified ZCW grid and a Fibonacci spherical code, which are new in the context of EPR simulations. For the investigated grids, the EPR metrics bring more information than the homogeneity quantities and are better related to the grids' EPR behaviour, for different spin system symmetries. The metrics' efficiency and limits are finally verified for grids generated from the initial ones, by using the original or magnetic field-constraint variants of the Spherical Centroidal Voronoi Tessellation method. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. Hierarchical Controlled Grid-Connected Microgrid based on a Novel Autonomous Current Sharing Controller

    DEFF Research Database (Denmark)

    Guan, Yajuan; Quintero, Juan Carlos Vasquez; Guerrero, Josep M.

    2015-01-01

    In this paper, a hierarchical control system based on a novel autonomous current sharing controller for grid-connected microgrids (MGs) is presented. A three-level hierarchical control system is implemented to guarantee the power sharing performance among voltage controlled parallel inverters......, while providing the required active and reactive power to the utility grid. A communication link is used to transmit the control signal from the tertiary and secondary control levels to the primary control. Simulation results from a MG based on two grid-connected parallel inverters are shown in order...

  9. Grid based calibration of SWAT hydrological models

    Directory of Open Access Journals (Sweden)

    D. Gorgan

    2012-07-01

    Full Text Available The calibration and execution of large hydrological models, such as SWAT (soil and water assessment tool, developed for large areas, high resolution, and huge input data, need not only quite a long execution time but also high computation resources. SWAT hydrological model supports studies and predictions of the impact of land management practices on water, sediment, and agricultural chemical yields in complex watersheds. The paper presents the gSWAT application as a web practical solution for environmental specialists to calibrate extensive hydrological models and to run scenarios, by hiding the complex control of processes and heterogeneous resources across the grid based high computation infrastructure. The paper highlights the basic functionalities of the gSWAT platform, and the features of the graphical user interface. The presentation is concerned with the development of working sessions, interactive control of calibration, direct and basic editing of parameters, process monitoring, and graphical and interactive visualization of the results. The experiments performed on different SWAT models and the obtained results argue the benefits brought by the grid parallel and distributed environment as a solution for the processing platform. All the instances of SWAT models used in the reported experiments have been developed through the enviroGRIDS project, targeting the Black Sea catchment area.

  10. A non-conformal finite element/finite volume scheme for the non-structured grid-based approximation of low Mach number flows

    International Nuclear Information System (INIS)

    Ansanay-Alex, G.

    2009-01-01

    The development of simulation codes aimed at a precise simulation of fires requires a precise approach of flame front phenomena by using very fine grids. The need to take different spatial scale into consideration leads to a local grid refinement and to a discretization with homogeneous grid for computing time and memory purposes. The author reports the approximation of the non-linear convection term, the scalar advection-diffusion in finite volumes, numerical simulations of a flow in a bent tube, of a three-dimensional laminar flame and of a low Mach number an-isotherm flow. Non conformal finite elements are also presented (Rannacher-Turek and Crouzeix-Raviart elements)

  11. Adaptation of Powerline Communications-Based Smart Metering Deployments to the Requirements of Smart Grids

    Directory of Open Access Journals (Sweden)

    Alberto Sendin

    2015-11-01

    Full Text Available Powerline communications (PLC-based smart meter deployments are now a reality in many regions of the world. Although PLC elements are generally incorporated in smart meters and data concentrators, the underlying PLC network allows the integration of other smart grid services directly over it. The remote control capabilities that automation programs need and are today deployed over their medium voltage (MV grid, can be extended to the low voltage (LV grid through these existing PLC networks. This paper demonstrates the capabilities of narrowband high data rate (NB HDR PLC technologies deployed over LV grids for smart metering purposes to support internet protocol internet protocol (IP communications in the LV grid. The paper demonstrates these possibilities with the presentation of the simulation and laboratory results of IP communications over international telecommunication union: ITU-T G.9904 PLC technology, and the definition of a PLC Network Management System based on a simple network management protocol (SNMP management information base (MIB definition and applicable use cases.

  12. The Knowledge Base Interface for Parametric Grid Information

    International Nuclear Information System (INIS)

    Hipp, James R.; Simons, Randall W.; Young, Chris J.

    1999-01-01

    The parametric grid capability of the Knowledge Base (KBase) provides an efficient robust way to store and access interpolatable information that is needed to monitor the Comprehensive Nuclear Test Ban Treaty. To meet both the accuracy and performance requirements of operational monitoring systems, we use an approach which combines the error estimation of kriging with the speed and robustness of Natural Neighbor Interpolation. The method involves three basic steps: data preparation, data storage, and data access. In past presentations we have discussed in detail the first step. In this paper we focus on the latter two, describing in detail the type of information which must be stored and the interface used to retrieve parametric grid data from the Knowledge Base. Once data have been properly prepared, the information (tessellation and associated value surfaces) needed to support the interface functionality, can be entered into the KBase. The primary types of parametric grid data that must be stored include (1) generic header information; (2) base model, station, and phase names and associated ID's used to construct surface identifiers; (3) surface accounting information; (4) tessellation accounting information; (5) mesh data for each tessellation; (6) correction data defined for each surface at each node of the surfaces owning tessellation (7) mesh refinement calculation set-up and flag information; and (8) kriging calculation set-up and flag information. The eight data components not only represent the results of the data preparation process but also include all required input information for several population tools that would enable the complete regeneration of the data results if that should be necessary

  13. Synchronization method for grid integrated battery storage systems during asymmetrical grid faults

    Directory of Open Access Journals (Sweden)

    Popadić Bane

    2017-01-01

    Full Text Available This paper aims at presenting a robust and reliable synchronization method for battery storage systems during asymmetrical grid faults. For this purpose, a Matlab/Simulink based model for testing of the power electronic interface between the grid and the battery storage systems has been developed. The synchronization method proposed in the paper is based on the proportional integral resonant controller with the delay signal cancellation. The validity of the synchronization method has been verified using the advanced laboratory station for the control of grid connected distributed energy sources. The proposed synchronization method has eliminated unfavourable components from the estimated grid angular frequency, leading to the more accurate and reliable tracking of the grid voltage vector positive sequence during both the normal operation and the operation during asymmetrical grid faults. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 042004: Integrated and Interdisciplinary Research entitled: Smart Electricity Distribution Grids Based on Distribution Management System and Distributed Generation

  14. Enhancing adaptive sparse grid approximations and improving refinement strategies using adjoint-based a posteriori error estimates

    Science.gov (United States)

    Jakeman, J. D.; Wildey, T.

    2015-01-01

    In this paper we present an algorithm for adaptive sparse grid approximations of quantities of interest computed from discretized partial differential equations. We use adjoint-based a posteriori error estimates of the physical discretization error and the interpolation error in the sparse grid to enhance the sparse grid approximation and to drive adaptivity of the sparse grid. Utilizing these error estimates provides significantly more accurate functional values for random samples of the sparse grid approximation. We also demonstrate that alternative refinement strategies based upon a posteriori error estimates can lead to further increases in accuracy in the approximation over traditional hierarchical surplus based strategies. Throughout this paper we also provide and test a framework for balancing the physical discretization error with the stochastic interpolation error of the enhanced sparse grid approximation.

  15. Enhancing adaptive sparse grid approximations and improving refinement strategies using adjoint-based a posteriori error estimates

    International Nuclear Information System (INIS)

    Jakeman, J.D.; Wildey, T.

    2015-01-01

    In this paper we present an algorithm for adaptive sparse grid approximations of quantities of interest computed from discretized partial differential equations. We use adjoint-based a posteriori error estimates of the physical discretization error and the interpolation error in the sparse grid to enhance the sparse grid approximation and to drive adaptivity of the sparse grid. Utilizing these error estimates provides significantly more accurate functional values for random samples of the sparse grid approximation. We also demonstrate that alternative refinement strategies based upon a posteriori error estimates can lead to further increases in accuracy in the approximation over traditional hierarchical surplus based strategies. Throughout this paper we also provide and test a framework for balancing the physical discretization error with the stochastic interpolation error of the enhanced sparse grid approximation

  16. Control strategy based on SPWM switching patterns for grid connected photovoltaic inverter

    Science.gov (United States)

    Hassaine, L.; Mraoui, A.

    2017-02-01

    Generally, for lower installation of photovoltaic systems connected to the grid, pulse width modulation (PWM) is a widely used technique for controlling the voltage source inverters injects currents into the grid. The current injected must be sinusoidal with reduced harmonic distortion. In this paper, a digital implementation of a control strategy based on PWM switching patterns for an inverter for photovoltaic system connected to the grid is presented. This strategy synchronize a sinusoidal inverter output current with a grid voltage The digital implementation of the proposed PWM switching pattern when is compared with the conventional one exhibit the advantage: Simplicity, reduction of the memory requirements and power calculation for the control

  17. An Efficient Topology-Based Algorithm for Transient Analysis of Power Grid

    KAUST Repository

    Yang, Lan

    2015-08-10

    In the design flow of integrated circuits, chip-level verification is an important step that sanity checks the performance is as expected. Power grid verification is one of the most expensive and time-consuming steps of chip-level verification, due to its extremely large size. Efficient power grid analysis technology is highly demanded as it saves computing resources and enables faster iteration. In this paper, a topology-base power grid transient analysis algorithm is proposed. Nodal analysis is adopted to analyze the topology which is mathematically equivalent to iteratively solving a positive semi-definite linear equation. The convergence of the method is proved.

  18. Power Grid Construction Project Portfolio Optimization Based on Bi-level programming model

    Science.gov (United States)

    Zhao, Erdong; Li, Shangqi

    2017-08-01

    As the main body of power grid operation, county-level power supply enterprises undertake an important emission to guarantee the security of power grid operation and safeguard social power using order. The optimization of grid construction projects has been a key issue of power supply capacity and service level of grid enterprises. According to the actual situation of power grid construction project optimization of county-level power enterprises, on the basis of qualitative analysis of the projects, this paper builds a Bi-level programming model based on quantitative analysis. The upper layer of the model is the target restriction of the optimal portfolio; the lower layer of the model is enterprises’ financial restrictions on the size of the enterprise project portfolio. Finally, using a real example to illustrate operation proceeding and the optimization result of the model. Through qualitative analysis and quantitative analysis, the bi-level programming model improves the accuracy and normative standardization of power grid enterprises projects.

  19. Homogeneity and EPR metrics for assessment of regular grids used in CW EPR powder simulations

    Science.gov (United States)

    Crăciun, Cora

    2014-08-01

    CW EPR powder spectra may be approximated numerically using a spherical grid and a Voronoi tessellation-based cubature. For a given spin system, the quality of simulated EPR spectra depends on the grid type, size, and orientation in the molecular frame. In previous work, the grids used in CW EPR powder simulations have been compared mainly from geometric perspective. However, some grids with similar homogeneity degree generate different quality simulated spectra. This paper evaluates the grids from EPR perspective, by defining two metrics depending on the spin system characteristics and the grid Voronoi tessellation. The first metric determines if the grid points are EPR-centred in their Voronoi cells, based on the resonance magnetic field variations inside these cells. The second metric verifies if the adjacent Voronoi cells of the tessellation are EPR-overlapping, by computing the common range of their resonance magnetic field intervals. Beside a series of well known regular grids, the paper investigates a modified ZCW grid and a Fibonacci spherical code, which are new in the context of EPR simulations. For the investigated grids, the EPR metrics bring more information than the homogeneity quantities and are better related to the grids’ EPR behaviour, for different spin system symmetries. The metrics’ efficiency and limits are finally verified for grids generated from the initial ones, by using the original or magnetic field-constraint variants of the Spherical Centroidal Voronoi Tessellation method.

  20. Fault ride-through capability of wind turbine connected to the grid in case of unbalanced voltages

    Directory of Open Access Journals (Sweden)

    Ivanović Zoran R.

    2016-01-01

    Full Text Available This paper deals with control of wind turbine connected to the grid through the back-to-back converter in case of unbalanced grid voltages. The motivation for this research has been found in recent transmission and distribution grid code, which demand modern wind turbines to stay connected to the grid and supply the highest possible apparent power during the grid disturbances. In order to comply with these requirements we proposed improved dual vector current controller to deal with the unbalance imposed by the electrical grid. Controller provides injection of active and reactive power to the grid, even if the voltages are lower than the nominal one. The results are validated using low power prototype and contemporary hardware-in-the-loop emulation platform. In both cases the controller is based on TMS320F2812 DSP. [Projekat Ministarstva nauke Republike Srbije, br. III 042004 and by the Provincial Secretariat for Science and Technological Development of AP Vojvodina under contract No. 114-451-3508/2013-04

  1. Parallelization Issues and Particle-In Codes.

    Science.gov (United States)

    Elster, Anne Cathrine

    1994-01-01

    "Everything should be made as simple as possible, but not simpler." Albert Einstein. The field of parallel scientific computing has concentrated on parallelization of individual modules such as matrix solvers and factorizers. However, many applications involve several interacting modules. Our analyses of a particle-in-cell code modeling charged particles in an electric field, show that these accompanying dependencies affect data partitioning and lead to new parallelization strategies concerning processor, memory and cache utilization. Our test-bed, a KSR1, is a distributed memory machine with a globally shared addressing space. However, most of the new methods presented hold generally for hierarchical and/or distributed memory systems. We introduce a novel approach that uses dual pointers on the local particle arrays to keep the particle locations automatically partially sorted. Complexity and performance analyses with accompanying KSR benchmarks, have been included for both this scheme and for the traditional replicated grids approach. The latter approach maintains load-balance with respect to particles. However, our results demonstrate it fails to scale properly for problems with large grids (say, greater than 128-by-128) running on as few as 15 KSR nodes, since the extra storage and computation time associated with adding the grid copies, becomes significant. Our grid partitioning scheme, although harder to implement, does not need to replicate the whole grid. Consequently, it scales well for large problems on highly parallel systems. It may, however, require load balancing schemes for non-uniform particle distributions. Our dual pointer approach may facilitate this through dynamically partitioned grids. We also introduce hierarchical data structures that store neighboring grid-points within the same cache -line by reordering the grid indexing. This alignment produces a 25% savings in cache-hits for a 4-by-4 cache. A consideration of the input data's effect on

  2. System Based Code: Principal Concept

    International Nuclear Information System (INIS)

    Yasuhide Asada; Masanori Tashimo; Masahiro Ueta

    2002-01-01

    This paper introduces a concept of the 'System Based Code' which has initially been proposed by the authors intending to give nuclear industry a leap of progress in the system reliability, performance improvement, and cost reduction. The concept of the System Based Code intends to give a theoretical procedure to optimize the reliability of the system by administrating every related engineering requirement throughout the life of the system from design to decommissioning. (authors)

  3. A NEW CODE FOR NONLINEAR FORCE-FREE FIELD EXTRAPOLATION OF THE GLOBAL CORONA

    International Nuclear Information System (INIS)

    Jiang Chaowei; Feng Xueshang; Xiang Changqing

    2012-01-01

    Reliable measurements of the solar magnetic field are still restricted to the photosphere, and our present knowledge of the three-dimensional coronal magnetic field is largely based on extrapolations from photospheric magnetograms using physical models, e.g., the nonlinear force-free field (NLFFF) model that is usually adopted. Most of the currently available NLFFF codes have been developed with computational volume such as a Cartesian box or a spherical wedge, while a global full-sphere extrapolation is still under development. A high-performance global extrapolation code is in particular urgently needed considering that the Solar Dynamics Observatory can provide a full-disk magnetogram with resolution up to 4096 × 4096. In this work, we present a new parallelized code for global NLFFF extrapolation with the photosphere magnetogram as input. The method is based on the magnetohydrodynamics relaxation approach, the CESE-MHD numerical scheme, and a Yin-Yang spherical grid that is used to overcome the polar problems of the standard spherical grid. The code is validated by two full-sphere force-free solutions from Low and Lou's semi-analytic force-free field model. The code shows high accuracy and fast convergence, and can be ready for future practical application if combined with an adaptive mesh refinement technique.

  4. The eGo grid model: An open-source and open-data based synthetic medium-voltage grid model for distribution power supply systems

    Science.gov (United States)

    Amme, J.; Pleßmann, G.; Bühler, J.; Hülk, L.; Kötter, E.; Schwaegerl, P.

    2018-02-01

    The increasing integration of renewable energy into the electricity supply system creates new challenges for distribution grids. The planning and operation of distribution systems requires appropriate grid models that consider the heterogeneity of existing grids. In this paper, we describe a novel method to generate synthetic medium-voltage (MV) grids, which we applied in our DIstribution Network GeneratOr (DINGO). DINGO is open-source software and uses freely available data. Medium-voltage grid topologies are synthesized based on location and electricity demand in defined demand areas. For this purpose, we use GIS data containing demand areas with high-resolution spatial data on physical properties, land use, energy, and demography. The grid topology is treated as a capacitated vehicle routing problem (CVRP) combined with a local search metaheuristics. We also consider the current planning principles for MV distribution networks, paying special attention to line congestion and voltage limit violations. In the modelling process, we included power flow calculations for validation. The resulting grid model datasets contain 3608 synthetic MV grids in high resolution, covering all of Germany and taking local characteristics into account. We compared the modelled networks with real network data. In terms of number of transformers and total cable length, we conclude that the method presented in this paper generates realistic grids that could be used to implement a cost-optimised electrical energy system.

  5. Operation of an InGrid based X-ray detector at the CAST experiment

    Science.gov (United States)

    Krieger, Christoph; Desch, Klaus; Kaminski, Jochen; Lupberger, Michael

    2018-02-01

    The CERN Axion Solar Telescope (CAST) is searching for axions and other particles which could be candidates for DarkMatter and even Dark Energy. These particles could be produced in the Sun and detected by a conversion into soft X-ray photons inside a strong magnetic field. In order to increase the sensitivity for physics beyond the Standard Model, detectors with a threshold below 1 keV as well as efficient background rejection methods are required to compensate for low energies and weak couplings resulting in very low detection rates. Those criteria are fulfilled by a detector utilizing the combination of a pixelized readout chip with an integrated Micromegas stage. These InGrid (Integrated Grid) devices can be build by photolithographic postprocessing techniques, resulting in a close to perfect match of grid and pixels facilitating the detection of single electrons on the chip surface. The high spatial resolution allows for energy determination by simple electron counting as well as for an event-shape based analysis as background rejection method. Tests at an X-ray generator revealed the energy threshold of an InGrid based X-ray detector to be well below the carbon Kα line at 277 eV. After the successful demonstration of the detectors key features, the detector was mounted at one of CAST's four detector stations behind an X-ray telescope in 2014. After several months of successful operation without any detector related interruptions, the InGrid based X-ray detector continues data taking at CAST in 2015. During operation at the experiment, background rates in the order of 10-5 keV-1 cm-2 s-1 have been achieved by application of a likelihood based method discriminating the non-photon background originating mostly from cosmic rays. For continued operation in 2016, an upgraded InGrid based detector is to be installed among other improvements including decoupling and sampling of the signal induced on the grid as well as a veto scintillator to further lower the

  6. Design of Energy Storage Management System Based on FPGA in Micro-Grid

    Science.gov (United States)

    Liang, Yafeng; Wang, Yanping; Han, Dexiao

    2018-01-01

    Energy storage system is the core to maintain the stable operation of smart micro-grid. Aiming at the existing problems of the energy storage management system in the micro-grid such as Low fault tolerance, easy to cause fluctuations in micro-grid, a new intelligent battery management system based on field programmable gate array is proposed : taking advantage of FPGA to combine the battery management system with the intelligent micro-grid control strategy. Finally, aiming at the problem that during estimation of battery charge State by neural network, initialization of weights and thresholds are not accurate leading to large errors in prediction results, the genetic algorithm is proposed to optimize the neural network method, and the experimental simulation is carried out. The experimental results show that the algorithm has high precision and provides guarantee for the stable operation of micro-grid.

  7. Development and verification of remote research environment based on 'Fusion research grid'

    International Nuclear Information System (INIS)

    Iba, Katsuyuki; Ozeki, Takahisa; Totsuka, Toshiyuki; Suzuki, Yoshio; Oshima, Takayuki; Sakata, Shinya; Sato, Minoru; Suzuki, Mitsuhiro; Hamamatsu, Kiyotaka; Kiyono, Kimihiro

    2008-01-01

    'Fusion research grid' is a concept that unites scientists and let them collaborate effectively against their difference in time zone and location in a nuclear fusion research. Fundamental technologies of 'Fusion research grid' have been developed at JAEA in the VizGrid project under the e-Japan project at the Ministry of Education, Culture, Sports, Science and Technology (MEXT). We are conscious of needs to create new systems that assist researchers with their research activities because remote collaborations have been increasing in international projects. Therefore we have developed prototype remote research environments for experiments, diagnostics, analyses and communications based on 'Fusion research grid'. All users can access these environments from anywhere because 'Fusion research grid' does not require a closed network like Super SINET to maintain security. The prototype systems were verified in experiments at JT-60U and their availability was confirmed

  8. AliEn - GRID application for ALICE Collaboration

    International Nuclear Information System (INIS)

    Zgura, Ion-Sorin

    2003-01-01

    AliEn (ALICE Environment) is a GRID framework built on top of the latest Internet standards for information exchange and authentication (SOAP, PKI) and common Open Source components. AliEn provides a virtual file catalogue that allows transparent access to distributed data-sets and a number of collaborating Web services which implement the authentication, job execution, file transport, performance monitor and event logging.The ALICE experiment has developed AliEn as an implementation of distributed computing infrastructure needed to simulate, reconstruct and analyze data from the experiment. The sites that belong to the ALICE Virtual Organisation can be seen and used as a single entity - any available node executes jobs and access to logical and datasets is transparent to the user. In developing AliEn common standards and solutions in the form of Open Source components were used. Only 1% (25k physical lines of code in Perl) is native AliEn code while 99% of the code has been imported in form of Open Sources packages and Perl modules. Currently ALICE is using the system for distributed production of Monte Carlo data at over 30 sites on four continents. During the last twelve months more than 30,000 jobs have been successfully run under AliEn control worldwide, totalling 25 CPU years and producing 20 TB of data. The user interface is compatible to EU DataGrid at the level of authentication and job description language. In perspective AliEn will be interfaced to the mainstream Grid infrastructure in HEP and it will remain to serve as interface between ALICE Offline framework and external Grid infrastructure. (authors)

  9. Development and Execution of an Impact Cratering Application on a Computational Grid

    Directory of Open Access Journals (Sweden)

    E. Huedo

    2005-01-01

    Full Text Available Impact cratering is an important geological process of special interest in Astrobiology. Its numerical simulation comprises the execution of a high number of tasks, since the search space of input parameter values includes the projectile diameter, the water depth and the impactor velocity. Furthermore, the execution time of each task is not uniform because of the different numerical properties of each experimental configuration. Grid technology is a promising platform to execute this kind of applications, since it provides the end user with a performance much higher than that achievable on any single organization. However, the scheduling of each task on a Grid involves challenging issues due to the unpredictable and heterogeneous behavior of both the Grid and the numerical code. This paper evaluates the performance of a Grid infrastructure based on the Globus toolkit and the GridWay framework, which provides the adaptive and fault tolerance functionality required to harness Grid resources, in the simulation of the impact cratering process. The experiments have been performed on a testbed composed of resources shared by five sites interconnected by RedIRIS, the Spanish Research and Education Network.

  10. Micro-grid platform based on NODE.JS architecture, implemented in electrical network instrumentation

    Science.gov (United States)

    Duque, M.; Cando, E.; Aguinaga, A.; Llulluna, F.; Jara, N.; Moreno, T.

    2016-05-01

    In this document, I propose a theory about the impact of systems based on microgrids in non-industrialized countries that have the goal to improve energy exploitation through alternatives methods of a clean and renewable energy generation and the creation of the app to manage the behavior of the micro-grids based on the NodeJS, Django and IOJS technologies. The micro-grids allow the optimal way to manage energy flow by electric injection directly in electric network small urban's cells in a low cost and available way. In difference from conventional systems, micro-grids can communicate between them to carry energy to places that have higher demand in accurate moments. This system does not require energy storage, so, costs are lower than conventional systems like fuel cells, solar panels or else; even though micro-grids are independent systems, they are not isolated. The impact that this analysis will generate, is the improvement of the electrical network without having greater control than an intelligent network (SMART-GRID); this leads to move to a 20% increase in energy use in a specified network; that suggest there are others sources of energy generation; but for today's needs, we need to standardize methods and remain in place to support all future technologies and the best option are the Smart Grids and Micro-Grids.

  11. A comparative study of the parabolized Navier-Stokes code using various grid-generation techniques

    Science.gov (United States)

    Kaul, U. K.; Chaussee, D. S.

    1985-01-01

    The parabolized Navier-Stokes (PNS) equations are used to calculate the flow-field characteristics about the hypersonic research aircraft X-24C. A comparison of the results obtained using elliptic, hyperbolic and algebraic grid generators is presented. The outer bow shock is treated as a sharp discontinuity, and the discontinuities within the shock layer are captured. Surface pressures and heat-transfer results at angles of attack of 6 deg and 20 deg, obtained using the three grid generators, are compared. The PNS equations are marched downstream over the body in both Cartesian and cylindrical base coordinate systems, and the results are compared. A robust marching procedure is demonstrated by successfully using large marching-step sizes with the implicit shock fitting procedure. A correlation is found between the marching-step size, Reynolds number and the angle of attack at fixed values of smoothing and stability coefficients for the marching scheme.

  12. Simulation-Based Approach for Studying the Balancing of Local Smart Grids with Electric Vehicle Batteries

    Directory of Open Access Journals (Sweden)

    Juhani Latvakoski

    2015-07-01

    Full Text Available Modern society is facing great challenges due to pollution and increased carbon dioxide (CO2 emissions. As part of solving these challenges, the use of renewable energy sources and electric vehicles (EVs is rapidly increasing. However, increased dynamics have triggered problems in balancing energy supply and consumption demand in the power systems. The resulting uncertainty and unpredictability of energy production, consumption, and management of peak loads has caused an increase in costs for energy market actors. Therefore, the means for studying the balancing of local smart grids with EVs is a starting point for this paper. The main contribution is a simulation-based approach which was developed to enable the study of the balancing of local distribution grids with EV batteries in a cost-efficient manner. The simulation-based approach is applied to enable the execution of a distributed system with the simulation of a local distribution grid, including a number of charging stations and EVs. A simulation system has been constructed to support the simulation-based approach. The evaluation has been carried out by executing the scenario related to balancing local distribution grids with EV batteries in a step-by-step manner. The evaluation results indicate that the simulation-based approach is able to facilitate the evaluation of smart grid– and EV-related communication protocols, control algorithms for charging, and functionalities of local distribution grids as part of a complex, critical cyber-physical system. In addition, the simulation system is able to incorporate advanced methods for monitoring, controlling, tracking, and modeling behavior. The simulation model of the local distribution grid can be executed with the smart control of charging and discharging powers of the EVs according to the load situation in the local distribution grid. The resulting simulation system can be applied to the study of balancing local smart grids with EV

  13. Croatia's rural areas - renewable energy based electricity generation for isolated grids

    Directory of Open Access Journals (Sweden)

    Protic Sonja Maria

    2014-01-01

    Full Text Available Several Western Balkan states face the consequences of the Yugoslavian war, which left hometowns with dilapidated electricity grid connections, a high average age of power plant capacities and low integration of renewable energy sources, grid bottlenecks and a lack of competition. In order to supply all households with electricity, UNDP Croatia did a research on decentralized supply systems based on renewable energy sources. Decentralized supply systems offer cheaper electricity connections and provide faster support to rural development. This paper proposes a developed methodology to financially compare isolated grid solutions that primarily use renewable energies to an extension of the public electricity network to small regions in Croatia. Isolated grid supply proves to be very often a preferable option. Furthermore, it points out the lack of a reliable evaluation of non-monetizable aspects and promotes a new interdisciplinary approach.

  14. Model atmospheres for M (sub)dwarf stars. 1: The base model grid

    Science.gov (United States)

    Allard, France; Hauschildt, Peter H.

    1995-01-01

    We have calculated a grid of more than 700 model atmospheres valid for a wide range of parameters encompassing the coolest known M dwarfs, M subdwarfs, and brown dwarf candidates: 1500 less than or equal to T(sub eff) less than or equal to 4000 K, 3.5 less than or equal to log g less than or equal to 5.5, and -4.0 less than or equal to (M/H) less than or equal to +0.5. Our equation of state includes 105 molecules and up to 27 ionization stages of 39 elements. In the calculations of the base grid of model atmospheres presented here, we include over 300 molecular bands of four molecules (TiO, VO, CaH, FeH) in the JOLA approximation, the water opacity of Ludwig (1971), collision-induced opacities, b-f and f-f atomic processes, as well as about 2 million spectral lines selected from a list with more than 42 million atomic and 24 million molecular (H2, CH, NH, OH, MgH, SiH, C2, CN, CO, SiO) lines. High-resolution synthetic spectra are obtained using an opacity sampling method. The model atmospheres and spectra are calculated with the generalized stellar atmosphere code PHOENIX, assuming LTE, plane-parallel geometry, energy (radiative plus convective) conservation, and hydrostatic equilibrium. The model spectra give close agreement with observations of M dwarfs across a wide spectral range from the blue to the near-IR, with one notable exception: the fit to the water bands. We discuss several practical applications of our model grid, e.g., broadband colors derived from the synthetic spectra. In light of current efforts to identify genuine brown dwarfs, we also show how low-resolution spectra of cool dwarfs vary with surface gravity, and how the high-regulation line profile of the Li I resonance doublet depends on the Li abundance.

  15. Geospatial Information Service System Based on GeoSOT Grid & Encoding

    Directory of Open Access Journals (Sweden)

    LI Shizhong

    2016-12-01

    Full Text Available With the rapid development of the space and earth observation technology, it is important to establish a multi-source, multi-scale and unified cross-platform reference for global data. In practice, the production and maintenance of geospatial data are scattered in different units, and the standard of the data grid varies between departments and systems. All these bring out the disunity of standards among different historical periods or orgnizations. Aiming at geospatial information security library for the national high resolution earth observation, there are some demands for global display, associated retrieval and template applications and other integrated services for geospatial data. Based on GeoSOT grid and encoding theory system, "geospatial information security library information of globally unified grid encoding management" data subdivision organization solutions have been proposed; system-level analyses, researches and designs have been carried out. The experimental results show that the data organization and management method based on GeoSOT can significantly improve the overall efficiency of the geospatial information security service system.

  16. Grid-based platform for training in Earth Observation

    Science.gov (United States)

    Petcu, Dana; Zaharie, Daniela; Panica, Silviu; Frincu, Marc; Neagul, Marian; Gorgan, Dorian; Stefanut, Teodor

    2010-05-01

    GiSHEO platform [1] providing on-demand services for training and high education in Earth Observation is developed, in the frame of an ESA funded project through its PECS programme, to respond to the needs of powerful education resources in remote sensing field. It intends to be a Grid-based platform of which potential for experimentation and extensibility are the key benefits compared with a desktop software solution. Near-real time applications requiring simultaneous multiple short-time-response data-intensive tasks, as in the case of a short time training event, are the ones that are proved to be ideal for this platform. The platform is based on Globus Toolkit 4 facilities for security and process management, and on the clusters of four academic institutions involved in the project. The authorization uses a VOMS service. The main public services are the followings: the EO processing services (represented through special WSRF-type services); the workflow service exposing a particular workflow engine; the data indexing and discovery service for accessing the data management mechanisms; the processing services, a collection allowing easy access to the processing platform. The WSRF-type services for basic satellite image processing are reusing free image processing tools, OpenCV and GDAL. New algorithms and workflows were develop to tackle with challenging problems like detecting the underground remains of old fortifications, walls or houses. More details can be found in [2]. Composed services can be specified through workflows and are easy to be deployed. The workflow engine, OSyRIS (Orchestration System using a Rule based Inference Solution), is based on DROOLS, and a new rule-based workflow language, SILK (SImple Language for worKflow), has been built. Workflow creation in SILK can be done with or without a visual designing tools. The basics of SILK are the tasks and relations (rules) between them. It is similar with the SCUFL language, but not relying on XML in

  17. Grid generation method to calculate the flow field in a three-dimensional cascade of blades. Sanjigen yokuretsu nagare keisan no tame no koshi keisei

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, K [National Aerospace Laboratory, Tokyo (Japan)

    1992-05-01

    For the purpose of developing a fan for an engine with ultra-high by-pass ratio, the design code of three-dimensional cascade of blades based on the Navier-Stokes equation has already been developed. This paper describes a method created by calculation grids which are part of this design code. This method is to generate boundary fitted grids to calculate the flow field across a cascade of blades placed radially in the axially symmetric space between hub and casing. In this method, one-period domain of the cascade of blades is mapped on a box in computational space by a series of combined streching transformation and conformal mapping. The grid in physical space is then obtained by successive inverse conformal mapping on the grid points in computational space. The grid obtained in this method is H-type and has a periodicity which includes the inclination of grid lines at the periodic boundary. As an example of the grid generated by this method, grids for primary and secondary models of the fan with ultra-high by-pass ratio are shown. 6 refs., 12 figs.

  18. Grid generation method to calculate the flow field in a three-dimensional cascade of blades; Sanjigen yokuretsu nagare keisan no tame no koshi keisei

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, K [National Aerospace Laboratory, Tokyo (Japan)

    1992-05-01

    For the purpose of developing a fan for an engine with ultra-high by-pass ratio, the design code of three-dimensional cascade of blades based on the Navier-Stokes equation has already been developed. This paper describes a method created by calculation grids which are part of this design code. This method is to generate boundary fitted grids to calculate the flow field across a cascade of blades placed radially in the axially symmetric space between hub and casing. In this method, one-period domain of the cascade of blades is mapped on a box in computational space by a series of combined streching transformation and conformal mapping. The grid in physical space is then obtained by successive inverse conformal mapping on the grid points in computational space. The grid obtained in this method is H-type and has a periodicity which includes the inclination of grid lines at the periodic boundary. As an example of the grid generated by this method, grids for primary and secondary models of the fan with ultra-high by-pass ratio are shown. 6 refs., 12 figs.

  19. Project Scheduling Heuristics-Based Standard PSO for Task-Resource Assignment in Heterogeneous Grid

    OpenAIRE

    Chen, Ruey-Maw; Wang, Chuin-Mu

    2011-01-01

    The task scheduling problem has been widely studied for assigning resources to tasks in heterogeneous grid environment. Effective task scheduling is an important issue for the performance of grid computing. Meanwhile, the task scheduling problem is an NP-complete problem. Hence, this investigation introduces a named “standard“ particle swarm optimization (PSO) metaheuristic approach to efficiently solve the task scheduling problems in grid. Meanwhile, two promising heuristics based on multimo...

  20. Intelligent Control of Micro Grid: A Big Data-Based Control Center

    Science.gov (United States)

    Liu, Lu; Wang, Yanping; Liu, Li; Wang, Zhiseng

    2018-01-01

    In this paper, a structure of micro grid system with big data-based control center is introduced. Energy data from distributed generation, storage and load are analized through the control center, and from the results new trends will be predicted and applied as a feedback to optimize the control. Therefore, each step proceeded in micro grid can be adjusted and orgnized in a form of comprehensive management. A framework of real-time data collection, data processing and data analysis will be proposed by employing big data technology. Consequently, a integrated distributed generation and a optimized energy storage and transmission process can be implemented in the micro grid system.

  1. A roadmap for caGrid, an enterprise Grid architecture for biomedical research.

    Science.gov (United States)

    Saltz, Joel; Hastings, Shannon; Langella, Stephen; Oster, Scott; Kurc, Tahsin; Payne, Philip; Ferreira, Renato; Plale, Beth; Goble, Carole; Ervin, David; Sharma, Ashish; Pan, Tony; Permar, Justin; Brezany, Peter; Siebenlist, Frank; Madduri, Ravi; Foster, Ian; Shanbhag, Krishnakant; Mead, Charlie; Chue Hong, Neil

    2008-01-01

    caGrid is a middleware system which combines the Grid computing, the service oriented architecture, and the model driven architecture paradigms to support development of interoperable data and analytical resources and federation of such resources in a Grid environment. The functionality provided by caGrid is an essential and integral component of the cancer Biomedical Informatics Grid (caBIG) program. This program is established by the National Cancer Institute as a nationwide effort to develop enabling informatics technologies for collaborative, multi-institutional biomedical research with the overarching goal of accelerating translational cancer research. Although the main application domain for caGrid is cancer research, the infrastructure provides a generic framework that can be employed in other biomedical research and healthcare domains. The development of caGrid is an ongoing effort, adding new functionality and improvements based on feedback and use cases from the community. This paper provides an overview of potential future architecture and tooling directions and areas of improvement for caGrid and caGrid-like systems. This summary is based on discussions at a roadmap workshop held in February with participants from biomedical research, Grid computing, and high performance computing communities.

  2. Asymmetrical Grid Fault Ride-Through Strategy of Three-phase Grid-connected Inverter Considering Network Impedance Impact in Low Voltage Grid

    DEFF Research Database (Denmark)

    Guo, Xiaoqiang; Zhang, Xue; Wang, Baocheng

    2014-01-01

    This letter presents a new control strategy of threephase grid-connected inverter for the positive sequence voltage recovery and negative sequence voltage reduction under asymmetrical grid faults. Unlike the conventional control strategy based on an assumption that the network impedance is mainly...... of the proposed solution for the flexible voltage support in a low-voltage grid, where thenetwork impedance is mainly resistive.......This letter presents a new control strategy of threephase grid-connected inverter for the positive sequence voltage recovery and negative sequence voltage reduction under asymmetrical grid faults. Unlike the conventional control strategy based on an assumption that the network impedance is mainly...... inductive, the proposed control strategy is more flexible and effective by considering the network impedance impact, which is of great importance for the high penetration of grid-connected renewable energy systems into low-voltage grids. The experimental tests are carried out to validate the effectiveness...

  3. Photovoltaic Grid-Connected Modeling and Characterization Based on Experimental Results.

    Science.gov (United States)

    Humada, Ali M; Hojabri, Mojgan; Sulaiman, Mohd Herwan Bin; Hamada, Hussein M; Ahmed, Mushtaq N

    2016-01-01

    A grid-connected photovoltaic (PV) system operates under fluctuated weather condition has been modeled and characterized based on specific test bed. A mathematical model of a small-scale PV system has been developed mainly for residential usage, and the potential results have been simulated. The proposed PV model based on three PV parameters, which are the photocurrent, IL, the reverse diode saturation current, Io, the ideality factor of diode, n. Accuracy of the proposed model and its parameters evaluated based on different benchmarks. The results showed that the proposed model fitting the experimental results with high accuracy compare to the other models, as well as the I-V characteristic curve. The results of this study can be considered valuable in terms of the installation of a grid-connected PV system in fluctuated climatic conditions.

  4. Combining Market-Based Control with Distribution Grid Constraints when Coordinating Electric Vehicle Charging

    Directory of Open Access Journals (Sweden)

    Geert Deconinck

    2015-12-01

    Full Text Available The charging of electric vehicles (EVs impacts the distribution grid, and its cost depends on the price of electricity when charging. An aggregator that is responsible for a large fleet of EVs can use a market-based control algorithm to coordinate the charging of these vehicles, in order to minimize the costs. In such an optimization, the operational parameters of the distribution grid, to which the EVs are connected, are not considered. This can lead to violations of the technical constraints of the grid (e.g., under-voltage, phase unbalances; for example, because many vehicles start charging simultaneously when the price is low. An optimization that simultaneously takes the economic and technical aspects into account is complex, because it has to combine time-driven control at the market level with event-driven control at the operational level. Different case studies investigate under which circumstances the market-based control, which coordinates EV charging, conflicts with the operational constraints of the distribution grid. Especially in weak grids, phase unbalance and voltage issues arise with a high share of EVs. A low-level voltage droop controller at the charging point of the EV can be used to avoid many grid constraint violations, by reducing the charge power if the local voltage is too low. While this action implies a deviation from the cost-optimal operating point, it is shown that this has a very limited impact on the business case of an aggregator, and is able to comply with the technical distribution grid constraints, even in weak distribution grids with many EVs.

  5. Au-coated X-ray Anti-scattering Grid Performance Test by MCNP

    Energy Technology Data Exchange (ETDEWEB)

    Bae, JunWoo; Yoo, Dong Han; Kim, Hee Reyoung [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2014-10-15

    It is required to protect individual against the dangers of ionizing radiation from medical exposure. And increasing of resolution for x-ray radiography tools can give radiation protectoral benefits. Because the image device has higher resolution in same energy source, it requires low energy level source and it can reduce individual dose. The anti-scattering grid is sub-device that is attached in front of detector (direction of source). It is square lattice shape generally. It is composed of penetration parts and shielding parts. Penetration part is generally air (the void) and in some studies it uses wood or aluminum. Shielding part is composed of various materials such as lead or copper. In this study, it is focused on the gold as one of X-ray grid materials, where gold is generally known as excellent shielding material and the performance test on the gold coated anti-scattering grid is carried out by MCNP simulation. X-ray grid was simulated by using MCNP code and its performance was investigated. It was understood that glass based and Au-coated grid could lessen the scattered photons more where the reduction was about two third. In further study, geometry optimization or material selection will be conducted by MCNP simulation for giving benefits to design proper grid for various instruments.

  6. Non-binary unitary error bases and quantum codes

    Energy Technology Data Exchange (ETDEWEB)

    Knill, E.

    1996-06-01

    Error operator bases for systems of any dimension are defined and natural generalizations of the bit-flip/ sign-change error basis for qubits are given. These bases allow generalizing the construction of quantum codes based on eigenspaces of Abelian groups. As a consequence, quantum codes can be constructed form linear codes over {ital Z}{sub {ital n}} for any {ital n}. The generalization of the punctured code construction leads to many codes which permit transversal (i.e. fault tolerant) implementations of certain operations compatible with the error basis.

  7. Framework for Interactive Parallel Dataset Analysis on the Grid

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, David A.; Ananthan, Balamurali; /Tech-X Corp.; Johnson, Tony; Serbo, Victor; /SLAC

    2007-01-10

    We present a framework for use at a typical Grid site to facilitate custom interactive parallel dataset analysis targeting terabyte-scale datasets of the type typically produced by large multi-institutional science experiments. We summarize the needs for interactive analysis and show a prototype solution that satisfies those needs. The solution consists of desktop client tool and a set of Web Services that allow scientists to sign onto a Grid site, compose analysis script code to carry out physics analysis on datasets, distribute the code and datasets to worker nodes, collect the results back to the client, and to construct professional-quality visualizations of the results.

  8. An adaptive multi-agent-based approach to smart grids control and optimization

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Marco [Florida Institute of Technology, Melbourne, FL (United States); Perez, Carlos; Granados, Adrian [Institute for Human and Machine Cognition, Ocala, FL (United States)

    2012-03-15

    In this paper, we describe a reinforcement learning-based approach to power management in smart grids. The scenarios we consider are smart grid settings where renewable power sources (e.g. Photovoltaic panels) have unpredictable variations in power output due, for example, to weather or cloud transient effects. Our approach builds on a multi-agent system (MAS)-based infrastructure for the monitoring and coordination of smart grid environments with renewable power sources and configurable energy storage devices (battery banks). Software agents are responsible for tracking and reporting power flow variations at different points in the grid, and to optimally coordinate the engagement of battery banks (i.e. charge/idle/discharge modes) to maintain energy requirements to end-users. Agents are able to share information and coordinate control actions through a parallel communications infrastructure, and are also capable of learning, from experience, how to improve their response strategies for different operational conditions. In this paper we describe our approach and address some of the challenges associated with the communications infrastructure for distributed coordination. We also present some preliminary results of our first simulations using the GridLAB-D simulation environment, created by the US Department of Energy (DoE) at Pacific Northwest National Laboratory (PNNL). (orig.)

  9. Wireless Sensor Network Based Smart Grid Communications: Cyber Attacks, Intrusion Detection System and Topology Control

    Directory of Open Access Journals (Sweden)

    Lipi Chhaya

    2017-01-01

    Full Text Available The existing power grid is going through a massive transformation. Smart grid technology is a radical approach for improvisation in prevailing power grid. Integration of electrical and communication infrastructure is inevitable for the deployment of Smart grid network. Smart grid technology is characterized by full duplex communication, automatic metering infrastructure, renewable energy integration, distribution automation and complete monitoring and control of entire power grid. Wireless sensor networks (WSNs are small micro electrical mechanical systems that are deployed to collect and communicate the data from surroundings. WSNs can be used for monitoring and control of smart grid assets. Security of wireless sensor based communication network is a major concern for researchers and developers. The limited processing capabilities of wireless sensor networks make them more vulnerable to cyber-attacks. The countermeasures against cyber-attacks must be less complex with an ability to offer confidentiality, data readiness and integrity. The address oriented design and development approach for usual communication network requires a paradigm shift to design data oriented WSN architecture. WSN security is an inevitable part of smart grid cyber security. This paper is expected to serve as a comprehensive assessment and analysis of communication standards, cyber security issues and solutions for WSN based smart grid infrastructure.

  10. High density grids

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Aina E.; Baxter, Elizabeth L.

    2018-01-16

    An X-ray data collection grid device is provided that includes a magnetic base that is compatible with robotic sample mounting systems used at synchrotron beamlines, a grid element fixedly attached to the magnetic base, where the grid element includes at least one sealable sample window disposed through a planar synchrotron-compatible material, where the planar synchrotron-compatible material includes at least one automated X-ray positioning and fluid handling robot fiducial mark.

  11. GSIMF: a web service based software and database management system for the next generation grids

    International Nuclear Information System (INIS)

    Wang, N; Ananthan, B; Gieraltowski, G; May, E; Vaniachine, A

    2008-01-01

    To process the vast amount of data from high energy physics experiments, physicists rely on Computational and Data Grids; yet, the distribution, installation, and updating of a myriad of different versions of different programs over the Grid environment is complicated, time-consuming, and error-prone. Our Grid Software Installation Management Framework (GSIMF) is a set of Grid Services that has been developed for managing versioned and interdependent software applications and file-based databases over the Grid infrastructure. This set of Grid services provide a mechanism to install software packages on distributed Grid computing elements, thus automating the software and database installation management process on behalf of the users. This enables users to remotely install programs and tap into the computing power provided by Grids

  12. Mini-grid based off-grid electrification to enhance electricity access in developing countries: What policies may be required?

    International Nuclear Information System (INIS)

    Bhattacharyya, Subhes C.; Palit, Debajit

    2016-01-01

    With 1.2 billion people still lacking electricity access by 2013, electricity access remains a major global challenge. Although mini-grid based electrification has received attention in recent times, their full exploitation requires policy support covering a range of areas. Distilling the experience from a five year research project, OASYS South Asia, this paper presents the summary of research findings and shares the experience from four demonstration activities. It suggests that cost-effective universal electricity service remains a challenge and reaching the universal electrification target by 2030 will remain a challenge for the less developed countries. The financial, organisational and governance weaknesses hinder successful implementation of projects in many countries. The paper then provides 10 policy recommendations to promote mini-grids as a complementary route to grid extension to promote electricity access for successful outcomes. - Highlights: •The academic and action research activities undertaken through OASYS South Asia Project are reported. •Evidence produced through a multi-dimensional participatory framework supplemented by four demonstration projects. •Funding and regulatory challenges militate against universal electrification objectives by 2030. •Innovative business approaches linking local mini-grids and livelihood opportunities exist. •Enabling policies are suggested to exploit such options.

  13. Grid Integration Issues for Large Scale Wind Power Plants (WPPs)

    DEFF Research Database (Denmark)

    Wu, Qiuwei; Xu, Zhao; Østergaard, Jacob

    2010-01-01

    transmission system operators (TSOs) over the world have come up the grid codes to request the wind power plants (WPPs) to have more or less the same operating capability as the conventional power plants. The grid codes requirements from other TSOs are under development. This paper covers the steady state......The penetration level of wind power into the power system over the world have been increasing very fast in the last few years and is still keeping the fast growth rate. It is just a matter of time that the wind power will be comparable to the conventional power generation. Therefore, many...

  14. Experimental and computational investigations of heat and mass transfer of intensifier grids

    International Nuclear Information System (INIS)

    Kobzar, Leonid; Oleksyuk, Dmitry; Semchenkov, Yuriy

    2015-01-01

    The paper discusses experimental and numerical investigations on intensification of thermal and mass exchange which were performed by National Research Centre ''Kurchatov Institute'' over the past years. Recently, many designs of heat mass transfer intensifier grids have been proposed. NRC ''Kurchatov Institute'' has accomplished a large scope of experimental investigations to study efficiency of intensifier grids of various types. The outcomes of experimental investigations can be used in verification of computational models and codes. On the basis of experimental data, we derived correlations to calculate coolant mixing and critical heat flux mixing in rod bundles equipped with intensifier grids. The acquired correlations were integrated in subchannel code SC-INT.

  15. Trusted data management for Grid-based medical applications

    NARCIS (Netherlands)

    van 't Noordende, G.J.; Olabarriaga, S.D.; Koot, M.R.; de Laat, C.T.A.M.; Udoh, E.

    2011-01-01

    Existing Grid technology has been foremost designed with performance and scalability in mind. When using Grid infrastructure for medical applications, privacy and security considerations become paramount. Privacy aspects require a re-thinking of the design and implementation of common Grid

  16. A Stationary Reference Frame Grid Synchronization System for Three-Phase Grid-Connected Power Converters Under Adverse Grid Conditions

    DEFF Research Database (Denmark)

    Rodríguez, P.; Luna, A.; Muñoz-Aguilar, R. S.

    2012-01-01

    synchronization method for three-phase three-wire networks, namely dual second-order generalized integrator (SOGI) frequency-locked loop. The method is based on two adaptive filters, implemented by using a SOGI on the stationary αβ reference frame, and it is able to perform an excellent estimation......Grid synchronization algorithms are of great importance in the control of grid-connected power converters, as fast and accurate detection of the grid voltage parameters is crucial in order to implement stable control strategies under generic grid conditions. This paper presents a new grid...

  17. Optimal Control of Micro Grid Operation Mode Seamless Switching Based on Radau Allocation Method

    Science.gov (United States)

    Chen, Xiaomin; Wang, Gang

    2017-05-01

    The seamless switching process of micro grid operation mode directly affects the safety and stability of its operation. According to the switching process from island mode to grid-connected mode of micro grid, we establish a dynamic optimization model based on two grid-connected inverters. We use Radau allocation method to discretize the model, and use Newton iteration method to obtain the optimal solution. Finally, we implement the optimization mode in MATLAB and get the optimal control trajectory of the inverters.

  18. Interior point algorithm-based power flow optimisation of a combined AC and DC multi-terminal grid

    Directory of Open Access Journals (Sweden)

    Farhan Beg

    2015-01-01

    Full Text Available The high cost of power electronic equipment, lower reliability and poor power handling capacity of the semiconductor devices had stalled the deployment of systems based on DC (multi-terminal direct current system (MTDC networks. The introduction of voltage source converters (VSCs for transmission has renewed the interest in the development of large interconnected grids based on both alternate current (AC and DC transmission networks. Such a grid platform also realises the added advantage of integrating the renewable energy sources into the grid. Thus a grid based on DC MTDC network is a possible solution to improve energy security and check the increasing supply demand gap. An optimal power solution for combined AC and DC grids obtained by the solution of the interior point algorithm is proposed in this study. Multi-terminal HVDC grids lie at the heart of various suggested transmission capacity increases. A significant difference is observed when MTDC grids are solved for power flows in place of conventional AC grids. This study deals with the power flow problem of a combined MTDC and an AC grid. The AC side is modelled with the full power flow equations and the VSCs are modelled using a connecting line, two generators and an AC node. The VSC and the DC losses are also considered. The optimisation focuses on several different goals. Three different scenarios are presented in an arbitrary grid network with ten AC nodes and five converter stations.

  19. Computer Simulation of the UMER Gridded Gun

    CERN Document Server

    Haber, Irving; Friedman, Alex; Grote, D P; Kishek, Rami A; Reiser, Martin; Vay, Jean-Luc; Zou, Yun

    2005-01-01

    The electron source in the University of Maryland Electron Ring (UMER) injector employs a grid 0.15 mm from the cathode to control the current waveform. Under nominal operating conditions, the grid voltage during the current pulse is sufficiently positive relative to the cathode potential to form a virtual cathode downstream of the grid. Three-dimensional computer simulations have been performed that use the mesh refinement capability of the WARP particle-in-cell code to examine a small region near the beam center in order to illustrate some of the complexity that can result from such a gridded structure. These simulations have been found to reproduce the hollowed velocity space that is observed experimentally. The simulations also predict a complicated time-dependent response to the waveform applied to the grid during the current turn-on. This complex temporal behavior appears to result directly from the dynamics of the virtual cathode formation and may therefore be representative of the expected behavior in...

  20. Group representations, error bases and quantum codes

    Energy Technology Data Exchange (ETDEWEB)

    Knill, E

    1996-01-01

    This report continues the discussion of unitary error bases and quantum codes. Nice error bases are characterized in terms of the existence of certain characters in a group. A general construction for error bases which are non-abelian over the center is given. The method for obtaining codes due to Calderbank et al. is generalized and expressed purely in representation theoretic terms. The significance of the inertia subgroup both for constructing codes and obtaining the set of transversally implementable operations is demonstrated.

  1. Modular Multilevel Converters Based Variable Speed Wind Turbines for Grid Faults

    DEFF Research Database (Denmark)

    Deng, Fujin; Liu, Dong; Wang, Yanbo

    2016-01-01

    in the dc-link of the power converter to improve system performance, but also ensure the grid-side current balancing to increase the generated power of the wind turbine under the unbalanced grid fault, in comparison with the conventional VSWT based on BTB three-level NPC converters. The simulation studies......The modular multilevel converter (MMC) becomes attractive in the medium- and high-power application with high modularity. In this paper, the MMC is proposed to be applied in the variable speed wind turbine (VSWT) based on the full-scale back-to-back (BTB) power converter, where the generator...

  2. A priori modeling of chemical reactions on computational grid platforms: Workflows and data models

    International Nuclear Information System (INIS)

    Rampino, S.; Monari, A.; Rossi, E.; Evangelisti, S.; Laganà, A.

    2012-01-01

    Graphical abstract: The quantum framework of the Grid Empowered Molecular Simulator GEMS assembled on the European Grid allows the ab initio evaluation of the dynamics of small systems starting from the calculation of the electronic properties. Highlights: ► The grid based GEMS simulator accurately models small chemical systems. ► Q5Cost and D5Cost file formats provide interoperability in the workflow. ► Benchmark runs on H + H 2 highlight the Grid empowering. ► O + O 2 and N + N 2 calculated k (T)’s fall within the error bars of the experiment. - Abstract: The quantum framework of the Grid Empowered Molecular Simulator GEMS has been assembled on the segment of the European Grid devoted to the Computational Chemistry Virtual Organization. The related grid based workflow allows the ab initio evaluation of the dynamics of small systems starting from the calculation of the electronic properties. Interoperability between computational codes across the different stages of the workflow was made possible by the use of the common data formats Q5Cost and D5Cost. Illustrative benchmark runs have been performed on the prototype H + H 2 , N + N 2 and O + O 2 gas phase exchange reactions and thermal rate coefficients have been calculated for the last two. Results are discussed in terms of the modeling of the interaction and advantages of using the Grid is highlighted.

  3. Comparison of control strategies for Doubly fed induction generator under recurring grid faults

    DEFF Research Database (Denmark)

    Chen, Wenjie; Blaabjerg, Frede; Zhu, Nan

    2014-01-01

    The new grid codes demand the wind turbine systems to ride through recurring grid faults. Many control strategies have been proposed for the Doubly Fed Induction Generator under single grid fault, but their performance under recurring grid faults have not been studied yet. In this paper, five...... different control strategies for DFIG to ride through single grid faults are presented, and their performance under recurring grid faults are analyzed. The controllable range, stator time constant and torque fluctuations of the DFIG with different control strategies are compared. The results are verified...

  4. Grid regulation services for energy storage devices based on grid frequency

    Energy Technology Data Exchange (ETDEWEB)

    Pratt, Richard M.; Hammerstrom, Donald J.; Kintner-Meyer, Michael C. W.; Tuffner, Francis K.

    2017-09-05

    Disclosed herein are representative embodiments of methods, apparatus, and systems for charging and discharging an energy storage device connected to an electrical power distribution system. In one exemplary embodiment, a controller monitors electrical characteristics of an electrical power distribution system and provides an output to a bi-directional charger causing the charger to charge or discharge an energy storage device (e.g., a battery in a plug-in hybrid electric vehicle (PHEV)). The controller can help stabilize the electrical power distribution system by increasing the charging rate when there is excess power in the electrical power distribution system (e.g., when the frequency of an AC power grid exceeds an average value), or by discharging power from the energy storage device to stabilize the grid when there is a shortage of power in the electrical power distribution system (e.g., when the frequency of an AC power grid is below an average value).

  5. Grid regulation services for energy storage devices based on grid frequency

    Science.gov (United States)

    Pratt, Richard M; Hammerstrom, Donald J; Kintner-Meyer, Michael C.W.; Tuffner, Francis K

    2013-07-02

    Disclosed herein are representative embodiments of methods, apparatus, and systems for charging and discharging an energy storage device connected to an electrical power distribution system. In one exemplary embodiment, a controller monitors electrical characteristics of an electrical power distribution system and provides an output to a bi-directional charger causing the charger to charge or discharge an energy storage device (e.g., a battery in a plug-in hybrid electric vehicle (PHEV)). The controller can help stabilize the electrical power distribution system by increasing the charging rate when there is excess power in the electrical power distribution system (e.g., when the frequency of an AC power grid exceeds an average value), or by discharging power from the energy storage device to stabilize the grid when there is a shortage of power in the electrical power distribution system (e.g., when the frequency of an AC power grid is below an average value).

  6. Bayesian grid matching

    DEFF Research Database (Denmark)

    Hartelius, Karsten; Carstensen, Jens Michael

    2003-01-01

    A method for locating distorted grid structures in images is presented. The method is based on the theories of template matching and Bayesian image restoration. The grid is modeled as a deformable template. Prior knowledge of the grid is described through a Markov random field (MRF) model which r...

  7. GSHR-Tree: a spatial index tree based on dynamic spatial slot and hash table in grid environments

    Science.gov (United States)

    Chen, Zhanlong; Wu, Xin-cai; Wu, Liang

    2008-12-01

    Computation Grids enable the coordinated sharing of large-scale distributed heterogeneous computing resources that can be used to solve computationally intensive problems in science, engineering, and commerce. Grid spatial applications are made possible by high-speed networks and a new generation of Grid middleware that resides between networks and traditional GIS applications. The integration of the multi-sources and heterogeneous spatial information and the management of the distributed spatial resources and the sharing and cooperative of the spatial data and Grid services are the key problems to resolve in the development of the Grid GIS. The performance of the spatial index mechanism is the key technology of the Grid GIS and spatial database affects the holistic performance of the GIS in Grid Environments. In order to improve the efficiency of parallel processing of a spatial mass data under the distributed parallel computing grid environment, this paper presents a new grid slot hash parallel spatial index GSHR-Tree structure established in the parallel spatial indexing mechanism. Based on the hash table and dynamic spatial slot, this paper has improved the structure of the classical parallel R tree index. The GSHR-Tree index makes full use of the good qualities of R-Tree and hash data structure. This paper has constructed a new parallel spatial index that can meet the needs of parallel grid computing about the magnanimous spatial data in the distributed network. This arithmetic splits space in to multi-slots by multiplying and reverting and maps these slots to sites in distributed and parallel system. Each sites constructs the spatial objects in its spatial slot into an R tree. On the basis of this tree structure, the index data was distributed among multiple nodes in the grid networks by using large node R-tree method. The unbalance during process can be quickly adjusted by means of a dynamical adjusting algorithm. This tree structure has considered the

  8. The biometric-based module of smart grid system

    Science.gov (United States)

    Engel, E.; Kovalev, I. V.; Ermoshkina, A.

    2015-10-01

    Within Smart Grid concept the flexible biometric-based module base on Principal Component Analysis (PCA) and selective Neural Network is developed. The formation of the selective Neural Network the biometric-based module uses the method which includes three main stages: preliminary processing of the image, face localization and face recognition. Experiments on the Yale face database show that (i) selective Neural Network exhibits promising classification capability for face detection, recognition problems; and (ii) the proposed biometric-based module achieves near real-time face detection, recognition speed and the competitive performance, as compared to some existing subspaces-based methods.

  9. Degenerate Quadtree Latitude/Longitude Grid Based on WGS-84 Ellipsoidal Facet

    Directory of Open Access Journals (Sweden)

    HU Bailin

    2016-12-01

    Full Text Available For the needs of digital earth development and solving many global problems, a new discrete global grid system-DQLLG (degenerate quadtree latitude/longitude grid was put forward, which was based on WGS-84 ellipsoidal facet. The hierarchical subdivision method, characteristics and grid column/row coordinate system were detailed. The Latitude/Longitude coordinate, area and side length of multi-resolution meshes on different subdivision levels were calculated. Then the changes of mesh areas and side lengths were analyzed and compared that with spherical DQLLG. The research indicates that the DQLLG had many excellent features:uniformity, hierarchy, consistency of direction, extensive data compatibility and so on. It has certain practicality for Global GIS in the future.

  10. Towards Agent-Based Model Specification in Smart Grid: A Cognitive Agent-based Computing Approach

    OpenAIRE

    Akram, Waseem; Niazi, Muaz A.; Iantovics, Laszlo Barna

    2017-01-01

    A smart grid can be considered as a complex network where each node represents a generation unit or a consumer. Whereas links can be used to represent transmission lines. One way to study complex systems is by using the agent-based modeling (ABM) paradigm. An ABM is a way of representing a complex system of autonomous agents interacting with each other. Previously, a number of studies have been presented in the smart grid domain making use of the ABM paradigm. However, to the best of our know...

  11. State of art in FE-based fuel performance codes

    International Nuclear Information System (INIS)

    Kim, Hyo Chan; Yang, Yong Sik; Kim, Dae Ho; Bang, Je Geon; Kim, Sun Ki; Koo, Yang Hyun

    2013-01-01

    Fuel performance codes approximate this complex behavior using an axisymmetric, axially-stacked, one-dimensional radial representation to save computation cost. However, the need for improved modeling of PCMI and, particularly, the importance of multidimensional capability for accurate fuel performance simulation has been identified as safety margin decreases. Finite element (FE) method that is reliable and proven solution in mechanical field has been introduced into fuel performance codes for multidimensional analysis. The present state of the art in numerical simulation of FE-based fuel performance predominantly involves 2-D axisymmetric model and 3-D volumetric model. The FRAPCON and FRAPTRAN own 1.5-D and 2-D FE model to simulate PCMI and cladding ballooning. In 2-D simulation, the FALCON code, developed by EPRI, is a 2-D (R-Z and R-θ) fully thermal-mechanically coupled steady-state and transient FE-based fuel behavior code. The French codes TOUTATIS and ALCYONE which are 3-D, and typically used to investigate localized behavior. In 2008, the Idaho National Laboratory (INL) has been developing multidimensional (2-D and 3-D) nuclear fuel performance code called BISON. In this paper, the current state of FE-based fuel performance code and their models are presented. Based on investigation into the codes, requirements and direction of development for new FE-based fuel performance code can be discussed. Based on comparison of models in FE-based fuel performance code, status of art in the codes can be discussed. A new FE-based fuel performance code should include typical pellet and cladding models which all codes own. In particular, specified pellet and cladding model such as gaseous swelling and high burnup structure (HBS) model should be developed to improve accuracy of code as well as consider AC condition. To reduce computation cost, the approximated gap and the optimized contact model should be also developed

  12. Photovoltaic Grid-Connected Modeling and Characterization Based on Experimental Results

    Science.gov (United States)

    Humada, Ali M.; Hojabri, Mojgan; Sulaiman, Mohd Herwan Bin; Hamada, Hussein M.; Ahmed, Mushtaq N.

    2016-01-01

    A grid-connected photovoltaic (PV) system operates under fluctuated weather condition has been modeled and characterized based on specific test bed. A mathematical model of a small-scale PV system has been developed mainly for residential usage, and the potential results have been simulated. The proposed PV model based on three PV parameters, which are the photocurrent, IL, the reverse diode saturation current, Io, the ideality factor of diode, n. Accuracy of the proposed model and its parameters evaluated based on different benchmarks. The results showed that the proposed model fitting the experimental results with high accuracy compare to the other models, as well as the I-V characteristic curve. The results of this study can be considered valuable in terms of the installation of a grid-connected PV system in fluctuated climatic conditions. PMID:27035575

  13. Preliminary validation of the MATRA-LMR-FB code for the flow blockage in a subassembly

    International Nuclear Information System (INIS)

    Jeong, H. Y.; Ha, K. S.; Kwon, Y. M.; Chang, W. P.; Lee, Y. B.; Heo, S.

    2005-01-01

    To analyze the flow blockage in a subassembly of a Liquid Metal-cooled Reactor (LMR), the MATRA-LMR-FB code has been developed and validated for the existing experimental data. Compared to the MATRA-LMR code, which had been successfully applied for the core thermal-hydraulic design of KALIMER, the MATRA-LMR-FB code includes some advanced modeling features. Firstly, the Distributed Resistance Model (DRM), which enables a very accurate description of the effects of wire-wrap and blockage in a flow path, is developed for the MATRA-LMR-FB code. Secondly, the hybrid difference method is used to minimize the numerical diffusion especially at the low flow region such as recirculating wakes after blockage. In addition, the code is equipped with various turbulent mixing models to describe the active mixing due to the turbulent motions as accurate as possible. For the validation of the MATRA-LMR-FB code the ORNL THORS test and KOS 169-pin test are analyzed. Based on the analysis results for the temperature data, the accuracy of the code is evaluated quantitatively. The MATRA-LMR-FB code predicts very accurately the exit temperatures measured in the subassembly with wire-wrap. However, the predicted temperatures for the experiment with spacer grid show some deviations from the measured. To enhance the accuracy of the MATRA-LMR-FB for the flow path with grid spacers, it is suggested to improve the models for pressure loss due to spacer grid and the modeling method for blockage itself. The developed MATRA-LMR-FB code is evaluated to be applied to the flow blockage analysis of KALIMER-600 which adopts the wire-wrapped subassemblies

  14. A multi-agent based distributed energy management scheme for smart grid applications

    International Nuclear Information System (INIS)

    Radhakrishnan, Bharat Menon; Srinivasan, Dipti

    2016-01-01

    A multi-agent system based distributed EMS (energy management system) is proposed in this paper to perform optimal energy allocation and management for grids comprising of renewables, storage and distributed generation. The reliable and efficient operation of smart grids is slackened due to the presence of intermittent renewables. As the load demand and renewables are uncertain throughout the day, an energy management system is essential to ensure grid stability and achieve reductions in operation costs and CO_2 emissions. The main objectives of the proposed algorithm is to maintain power balance in the system and to ensure long cycle life for storage units by controlling their SOC (state of charge). The proposed EMS scheme is tested and validated on a practical test system, which replicates a small-scale smart grid with a variety of distributed sources, storage devices, loads, power electronic converters, and SCADA (supervisory control and data acquisition) system. This system is also connected to the utility grid and the power exchange is controlled with the help of a battery system through a fuzzy based decision-making framework. The proposed algorithm is also extensively verified and tested using a series of sensitivity analyses and benchmarking with existing algorithms. - Highlights: • An agent-based decentralized algorithm is proposed to perform energy management. • The multi-agent system approach eliminates the possibility of single point failures. • Adaptive fuzzy systems make the decision making more reliable, flexible and robust. • The algorithm is extensively tested and validated using sensitivity and verification analyses.

  15. Elliptic Curve Cryptography-Based Authentication with Identity Protection for Smart Grids.

    Directory of Open Access Journals (Sweden)

    Liping Zhang

    Full Text Available In a smart grid, the power service provider enables the expected power generation amount to be measured according to current power consumption, thus stabilizing the power system. However, the data transmitted over smart grids are not protected, and then suffer from several types of security threats and attacks. Thus, a robust and efficient authentication protocol should be provided to strength the security of smart grid networks. As the Supervisory Control and Data Acquisition system provides the security protection between the control center and substations in most smart grid environments, we focus on how to secure the communications between the substations and smart appliances. Existing security approaches fail to address the performance-security balance. In this study, we suggest a mitigation authentication protocol based on Elliptic Curve Cryptography with privacy protection by using a tamper-resistant device at the smart appliance side to achieve a delicate balance between performance and security of smart grids. The proposed protocol provides some attractive features such as identity protection, mutual authentication and key agreement. Finally, we demonstrate the completeness of the proposed protocol using the Gong-Needham-Yahalom logic.

  16. Elliptic Curve Cryptography-Based Authentication with Identity Protection for Smart Grids.

    Science.gov (United States)

    Zhang, Liping; Tang, Shanyu; Luo, He

    2016-01-01

    In a smart grid, the power service provider enables the expected power generation amount to be measured according to current power consumption, thus stabilizing the power system. However, the data transmitted over smart grids are not protected, and then suffer from several types of security threats and attacks. Thus, a robust and efficient authentication protocol should be provided to strength the security of smart grid networks. As the Supervisory Control and Data Acquisition system provides the security protection between the control center and substations in most smart grid environments, we focus on how to secure the communications between the substations and smart appliances. Existing security approaches fail to address the performance-security balance. In this study, we suggest a mitigation authentication protocol based on Elliptic Curve Cryptography with privacy protection by using a tamper-resistant device at the smart appliance side to achieve a delicate balance between performance and security of smart grids. The proposed protocol provides some attractive features such as identity protection, mutual authentication and key agreement. Finally, we demonstrate the completeness of the proposed protocol using the Gong-Needham-Yahalom logic.

  17. Air Pollution Monitoring and Mining Based on Sensor Grid in London

    OpenAIRE

    Ma, Yajie; Richards, Mark; Ghanem, Moustafa; Guo, Yike; Hassard, John

    2008-01-01

    In this paper, we present a distributed infrastructure based on wireless sensors network and Grid computing technology for air pollution monitoring and mining, which aims to develop low-cost and ubiquitous sensor networks to collect real-time, large scale and comprehensive environmental data from road traffic emissions for air pollution monitoring in urban environment. The main informatics challenges in respect to constructing the high-throughput sensor Grid are discussed in this paper. We pr...

  18. Benchmarking studies for the DESCARTES and CIDER codes

    International Nuclear Information System (INIS)

    Eslinger, P.W.; Ouderkirk, S.J.; Nichols, W.E.

    1993-01-01

    The Hanford Envirorunental Dose Reconstruction (HEDR) project is developing several computer codes to model the airborne release, transport, and envirormental accumulation of radionuclides resulting from Hanford operations from 1944 through 1972. In order to calculate the dose of radiation a person may have received in any given location, the geographic area addressed by the HEDR Project will be divided into a grid. The grid size suggested by the draft requirements contains 2091 units called nodes. Two of the codes being developed are DESCARTES and CIDER. The DESCARTES code will be used to estimate the concentration of radionuclides in environmental pathways from the output of the air transport code RATCHET. The CIDER code will use information provided by DESCARTES to estimate the dose received by an individual. The requirements that Battelle (BNW) set for these two codes were released to the HEDR Technical Steering Panel (TSP) in a draft document on November 10, 1992. This document reports on the preliminary work performed by the code development team to determine if the requirements could be met

  19. COARSE-GRID SIMULATION OF REACTING AND NON-REACTING GAS-PARTICLE FLOWS

    Energy Technology Data Exchange (ETDEWEB)

    Sankaran Sundaresan

    2004-03-01

    The principal goal of this project, funded under the ''DOE Vision 21 Virtual Demonstration Initiative'' is virtual demonstration of circulating fluidized bed performance. We had proposed a ''virtual demonstration tool'', which is based on the open-domain CFD code MFIX. The principal challenge funded through this grant is to devise and implement in this CFD code sound physical models for the rheological characteristics of the gas-particle mixtures. Within the past year, which was the third year of the project, we have made the following specific advances. (a) We have completed a study of the impact of sub-grid models of different levels of detail on the results obtained in coarse-grid simulations of gas-particle flow. (b) We have also completed a study of a model problem to understand the effect of wall friction, which was proved in our earlier work to be very important for stable operation of standpipes in a circulating fluidized bed circuit. These are described in a greater detail in this report.

  20. Collaborative Simulation Grid: Multiscale Quantum-Mechanical/Classical Atomistic Simulations on Distributed PC Clusters in the US and Japan

    Science.gov (United States)

    Kikuchi, Hideaki; Kalia, Rajiv; Nakano, Aiichiro; Vashishta, Priya; Iyetomi, Hiroshi; Ogata, Shuji; Kouno, Takahisa; Shimojo, Fuyuki; Tsuruta, Kanji; Saini, Subhash; hide

    2002-01-01

    A multidisciplinary, collaborative simulation has been performed on a Grid of geographically distributed PC clusters. The multiscale simulation approach seamlessly combines i) atomistic simulation backed on the molecular dynamics (MD) method and ii) quantum mechanical (QM) calculation based on the density functional theory (DFT), so that accurate but less scalable computations are performed only where they are needed. The multiscale MD/QM simulation code has been Grid-enabled using i) a modular, additive hybridization scheme, ii) multiple QM clustering, and iii) computation/communication overlapping. The Gridified MD/QM simulation code has been used to study environmental effects of water molecules on fracture in silicon. A preliminary run of the code has achieved a parallel efficiency of 94% on 25 PCs distributed over 3 PC clusters in the US and Japan, and a larger test involving 154 processors on 5 distributed PC clusters is in progress.

  1. Verification & Validation of High-Order Short-Characteristics-Based Deterministic Transport Methodology on Unstructured Grids

    International Nuclear Information System (INIS)

    Azmy, Yousry; Wang, Yaqi

    2013-01-01

    The research team has developed a practical, high-order, discrete-ordinates, short characteristics neutron transport code for three-dimensional configurations represented on unstructured tetrahedral grids that can be used for realistic reactor physics applications at both the assembly and core levels. This project will perform a comprehensive verification and validation of this new computational tool against both a continuous-energy Monte Carlo simulation (e.g. MCNP) and experimentally measured data, an essential prerequisite for its deployment in reactor core modeling. Verification is divided into three phases. The team will first conduct spatial mesh and expansion order refinement studies to monitor convergence of the numerical solution to reference solutions. This is quantified by convergence rates that are based on integral error norms computed from the cell-by-cell difference between the code's numerical solution and its reference counterpart. The latter is either analytic or very fine- mesh numerical solutions from independent computational tools. For the second phase, the team will create a suite of code-independent benchmark configurations to enable testing the theoretical order of accuracy of any particular discretization of the discrete ordinates approximation of the transport equation. For each tested case (i.e. mesh and spatial approximation order), researchers will execute the code and compare the resulting numerical solution to the exact solution on a per cell basis to determine the distribution of the numerical error. The final activity comprises a comparison to continuous-energy Monte Carlo solutions for zero-power critical configuration measurements at Idaho National Laboratory's Advanced Test Reactor (ATR). Results of this comparison will allow the investigators to distinguish between modeling errors and the above-listed discretization errors introduced by the deterministic method, and to separate the sources of uncertainty.

  2. Translation of ARAC computer codes

    International Nuclear Information System (INIS)

    Takahashi, Kunio; Chino, Masamichi; Honma, Toshimitsu; Ishikawa, Hirohiko; Kai, Michiaki; Imai, Kazuhiko; Asai, Kiyoshi

    1982-05-01

    In 1981 we have translated the famous MATHEW, ADPIC and their auxiliary computer codes for CDC 7600 computer version to FACOM M-200's. The codes consist of a part of the Atmospheric Release Advisory Capability (ARAC) system of Lawrence Livermore National Laboratory (LLNL). The MATHEW is a code for three-dimensional wind field analysis. Using observed data, it calculates the mass-consistent wind field of grid cells by a variational method. The ADPIC is a code for three-dimensional concentration prediction of gases and particulates released to the atmosphere. It calculates concentrations in grid cells by the particle-in-cell method. They are written in LLLTRAN, i.e., LLNL Fortran language and are implemented on the CDC 7600 computers of LLNL. In this report, i) the computational methods of the MATHEW/ADPIC and their auxiliary codes, ii) comparisons of the calculated results with our JAERI particle-in-cell, and gaussian plume models, iii) translation procedures from the CDC version to FACOM M-200's, are described. Under the permission of LLNL G-Division, this report is published to keep the track of the translation procedures and to serve our JAERI researchers for comparisons and references of their works. (author)

  3. Grid occupancy estimation for environment perception based on belief functions and PCR6

    Science.gov (United States)

    Moras, Julien; Dezert, Jean; Pannetier, Benjamin

    2015-05-01

    In this contribution, we propose to improve the grid map occupancy estimation method developed so far based on belief function modeling and the classical Dempster's rule of combination. Grid map offers a useful representation of the perceived world for mobile robotics navigation. It will play a major role for the security (obstacle avoidance) of next generations of terrestrial vehicles, as well as for future autonomous navigation systems. In a grid map, the occupancy of each cell representing a small piece of the surrounding area of the robot must be estimated at first from sensors measurements (typically LIDAR, or camera), and then it must also be classified into different classes in order to get a complete and precise perception of the dynamic environment where the robot moves. So far, the estimation and the grid map updating have been done using fusion techniques based on the probabilistic framework, or on the classical belief function framework thanks to an inverse model of the sensors. Mainly because the latter offers an interesting management of uncertainties when the quality of available information is low, and when the sources of information appear as conflicting. To improve the performances of the grid map estimation, we propose in this paper to replace Dempster's rule of combination by the PCR6 rule (Proportional Conflict Redistribution rule #6) proposed in DSmT (Dezert-Smarandache) Theory. As an illustrating scenario, we consider a platform moving in dynamic area and we compare our new realistic simulation results (based on a LIDAR sensor) with those obtained by the probabilistic and the classical belief-based approaches.

  4. Coding aperture applied to X-ray imaging

    International Nuclear Information System (INIS)

    Brunol, J.; Sauneuf, R.; Gex, J.P.

    1980-05-01

    We present some X-ray images of grids and plasmas. These images were obtained by using a single circular slit (annular code) as coding aperture and a computer decoding process. The experimental resolution is better than 10μm and it is expected to be in the order of 2 or 3 μm with the same code and an improved decoding process

  5. Grid generation methods

    CERN Document Server

    Liseikin, Vladimir D

    2010-01-01

    This book is an introduction to structured and unstructured grid methods in scientific computing, addressing graduate students, scientists as well as practitioners. Basic local and integral grid quality measures are formulated and new approaches to mesh generation are reviewed. In addition to the content of the successful first edition, a more detailed and practice oriented description of monitor metrics in Beltrami and diffusion equations is given for generating adaptive numerical grids. Also, new techniques developed by the author are presented, in particular a technique based on the inverted form of Beltrami’s partial differential equations with respect to control metrics. This technique allows the generation of adaptive grids for a wide variety of computational physics problems, including grid clustering to given function values and gradients, grid alignment with given vector fields, and combinations thereof. Applications of geometric methods to the analysis of numerical grid behavior as well as grid ge...

  6. Progress in 3D Space-charge Calculations in the GPT Code

    NARCIS (Netherlands)

    Pöplau, G.; Rienen, van U.; Loos, de M.J.; Geer, van der S.B.

    2004-01-01

    The mesh-based 3D space-charge routine in the GPT (General Particle Tracer, Pulsar Physics) code scales linearly with the number of particles in terms of CPU time and allows a million particles to be tracked on a normal PC. The crucial ingredient of the routine is a non-equidistant multi-grid

  7. Porting plasma physics simulation codes to modern computing architectures using the libmrc framework

    Science.gov (United States)

    Germaschewski, Kai; Abbott, Stephen

    2015-11-01

    Available computing power has continued to grow exponentially even after single-core performance satured in the last decade. The increase has since been driven by more parallelism, both using more cores and having more parallelism in each core, e.g. in GPUs and Intel Xeon Phi. Adapting existing plasma physics codes is challenging, in particular as there is no single programming model that covers current and future architectures. We will introduce the open-source libmrc framework that has been used to modularize and port three plasma physics codes: The extended MHD code MRCv3 with implicit time integration and curvilinear grids; the OpenGGCM global magnetosphere model; and the particle-in-cell code PSC. libmrc consolidates basic functionality needed for simulations based on structured grids (I/O, load balancing, time integrators), and also introduces a parallel object model that makes it possible to maintain multiple implementations of computational kernels, on e.g. conventional processors and GPUs. It handles data layout conversions and enables us to port performance-critical parts of a code to a new architecture step-by-step, while the rest of the code can remain unchanged. We will show examples of the performance gains and some physics applications.

  8. Energy efficiency analysis for flexible-grid OFDM-based optical networks

    DEFF Research Database (Denmark)

    Vizcaíno, Jorge López; Ye, Yabin; Tafur Monroy, Idelfonso

    2012-01-01

    As the Internet traffic grows, the energy efficiency gains more attention as a design factor for the planning and operation of telecommunication networks. This paper is devoted to the study of energy efficiency in optical transport networks, comparing the performance of an innovative flexible......-grid network based on Orthogonal Frequency Division Multiplexing (OFDM) with that of conventional fixed-grid Wavelength Division Multiplexing (WDM) networks with a Single Line Rate (SLR) and with a Mixed Line Rate (MLR) operation. The power consumption values of the network elements are introduced. Energy......-aware heuristic algorithms are proposed for the resource allocation both in static (offline) and dynamic (online) scenarios with time-varying demands for the Elastic-bandwidth OFDM-based network and the WDM networks (with SLR and MLR). The energy efficiency performance of the two network technologies under...

  9. Memory-efficient optimization of Gyrokinetic particle-to-grid interpolation for multicore processors

    Energy Technology Data Exchange (ETDEWEB)

    Madduri, Kamesh [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Williams, Samuel [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Ethier, Stephane [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Oliker, Leonid [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Shalf, John [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Strohmaier, Erich [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Yelicky, Katherine [Univ. of California, Berkeley, CA (United States)

    2009-01-01

    We present multicore parallelization strategies for the particle-to-grid interpolation step in the Gyrokinetic Toroidal Code (GTC), a 3D particle-in-cell (PIC) application to study turbulent transport in magnetic-confinement fusion devices. Particle-grid interpolation is a known performance bottleneck in several PIC applications. In GTC, this step involves particles depositing charges to a 3D toroidal mesh, and multiple particles may contribute to the charge at a grid point. We design new parallel algorithms for the GTC charge deposition kernel, and analyze their performance on three leading multicore platforms. We implement thirteen different variants for this kernel and identify the best-performing ones given typical PIC parameters such as the grid size, number of particles per cell, and the GTC-specific particle Larmor radius variation. We find that our best strategies can be 2x faster than the reference optimized MPI implementation, and our analysis provides insight into desirable architectural features for high-performance PIC simulation codes.

  10. Monte Carlo simulation of ion-neutral charge exchange collisions and grid erosion in an ion thruster

    Science.gov (United States)

    Peng, Xiaohang; Ruyten, Wilhelmus M.; Keefer, Dennis

    1991-01-01

    A combined particle-in-cell (PIC)/Monte Carlo simulation model has been developed in which the PIC method is used to simulate the charge exchange collisions. It is noted that a number of features were reproduced correctly by this code, but that its assumption of two-dimensional axisymmetry for a single set of grid apertures precluded the reproduction of the most characteristic feature of actual test data; namely, the concentrated grid erosion at the geometric center of the hexagonal aperture array. The first results of a three-dimensional code, which takes into account the hexagonal symmetry of the grid, are presented. It is shown that, with this code, the experimentally observed erosion patterns are reproduced correctly, demonstrating explicitly the concentration of sputtering between apertures.

  11. Optimization of the cooling circuit and thermo-mechanical analysis for the extraction grid of ELISE

    International Nuclear Information System (INIS)

    Nocentini, R.; Gutser, R.; Heinemann, B.; Froeschle, M.; Riedl, R.

    2011-01-01

    The NNBI test facility ELISE ('Extraction from a Large Ion Source Experiment'), presently under construction at IPP, will have an extraction area with the same width and half the height of the ITER source, acceleration up to 60 kV, for 10 s, every 180 s, and plasma generation up to 1 h. Electrons are co-extracted from the ion source. Suppression magnets in the extraction grid deflect the electrons onto the extraction grid surface. For 30 mA/cm 2 extracted electron current density and 10 kV extraction voltage, localized power density is in the order of 39 MW/m 2 near the grid apertures and a total heat load of 150 kW is deposited onto each extraction grid segment. Heat removal is provided by a water circuit inside the grid. For ELISE, a new cooling circuit has been developed to provide a more reliable operation. The optimization of the cooling circuit and the thermo-mechanical analysis of the extraction grid of ELISE, considering maximum grid temperature, mechanical stresses and grid deformation, has been performed using the codes KOBRA3, TrajAn, the ANSYS finite element package and the fluid dynamics code CFX.

  12. Probabilistic Modelling of Robustness and Resilience of Power Grid Systems

    DEFF Research Database (Denmark)

    Qin, Jianjun; Sansavini, Giovanni; Nielsen, Michael Havbro Faber

    2017-01-01

    The present paper proposes a framework for the modeling and analysis of resilience of networked power grid systems. A probabilistic systems model is proposed based on the JCSS Probabilistic Model Code (JCSS, 2001) and deterministic engineering systems modeling techniques such as the DC flow model...... cascading failure event scenarios (Nan and Sansavini, 2017). The concept of direct and indirect consequences proposed by the Joint Committee on Structural Safety (JCSS, 2008) is utilized to model the associated consequences. To facilitate a holistic modeling of robustness and resilience, and to identify how...... these characteristics may be optimized these characteristics, the power grid system is finally interlinked with its fundamental interdependent systems, i.e. a societal model, a regulatory system and control feedback loops. The proposed framework is exemplified with reference to optimal decision support for resilience...

  13. OGC and Grid Interoperability in enviroGRIDS Project

    Science.gov (United States)

    Gorgan, Dorian; Rodila, Denisa; Bacu, Victor; Giuliani, Gregory; Ray, Nicolas

    2010-05-01

    EnviroGRIDS (Black Sea Catchment Observation and Assessment System supporting Sustainable Development) [1] is a 4-years FP7 Project aiming to address the subjects of ecologically unsustainable development and inadequate resource management. The project develops a Spatial Data Infrastructure of the Black Sea Catchment region. The geospatial technologies offer very specialized functionality for Earth Science oriented applications as well as the Grid oriented technology that is able to support distributed and parallel processing. One challenge of the enviroGRIDS project is the interoperability between geospatial and Grid infrastructures by providing the basic and the extended features of the both technologies. The geospatial interoperability technology has been promoted as a way of dealing with large volumes of geospatial data in distributed environments through the development of interoperable Web service specifications proposed by the Open Geospatial Consortium (OGC), with applications spread across multiple fields but especially in Earth observation research. Due to the huge volumes of data available in the geospatial domain and the additional introduced issues (data management, secure data transfer, data distribution and data computation), the need for an infrastructure capable to manage all those problems becomes an important aspect. The Grid promotes and facilitates the secure interoperations of geospatial heterogeneous distributed data within a distributed environment, the creation and management of large distributed computational jobs and assures a security level for communication and transfer of messages based on certificates. This presentation analysis and discusses the most significant use cases for enabling the OGC Web services interoperability with the Grid environment and focuses on the description and implementation of the most promising one. In these use cases we give a special attention to issues such as: the relations between computational grid and

  14. A Data Transmission Algorithm Based on Dynamic Grid Division for Coal Goaf Temperature Monitoring

    Directory of Open Access Journals (Sweden)

    Qingsong Hu

    2014-01-01

    Full Text Available WSN (wireless sensor network is a perfect tool of temperature monitoring in coal goaf. Based on the three-zone theory of goaf, the GtmWSN model is proposed, and its dynamic features are analyzed. Accordingly, a data transmission scheme, named DTDGD, is worked out. Firstly, sink nodes conduct dynamic grid division on the GtmWSN according to virtual semicircle. Secondly, each node will confirm to which grid it belongs based on grid number. Finally, data will be delivered to sink nodes with greedy forward and hole avoidance. Simulation results and field data showed that the GtmWSN and DTDGD satisfied the lifetime need of goaf temperature monitoring.

  15. Development of authentication code for multi-access optical code division multiplexing based quantum key distribution

    Science.gov (United States)

    Taiwo, Ambali; Alnassar, Ghusoon; Bakar, M. H. Abu; Khir, M. F. Abdul; Mahdi, Mohd Adzir; Mokhtar, M.

    2018-05-01

    One-weight authentication code for multi-user quantum key distribution (QKD) is proposed. The code is developed for Optical Code Division Multiplexing (OCDMA) based QKD network. A unique address assigned to individual user, coupled with degrading probability of predicting the source of the qubit transmitted in the channel offer excellent secure mechanism against any form of channel attack on OCDMA based QKD network. Flexibility in design as well as ease of modifying the number of users are equally exceptional quality presented by the code in contrast to Optical Orthogonal Code (OOC) earlier implemented for the same purpose. The code was successfully applied to eight simultaneous users at effective key rate of 32 bps over 27 km transmission distance.

  16. MeshVoro: A Three-Dimensional Voronoi Mesh Building Tool for the TOUGH Family of Codes

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, C. M.; Boyle, K. L.; Reagan, M.; Johnson, J.; Rycroft, C.; Moridis, G. J.

    2013-09-30

    Few tools exist for creating and visualizing complex three-dimensional simulation meshes, and these have limitations that restrict their application to particular geometries and circumstances. Mesh generation needs to trend toward ever more general applications. To that end, we have developed MeshVoro, a tool that is based on the Voro (Rycroft 2009) library and is capable of generating complex threedimensional Voronoi tessellation-based (unstructured) meshes for the solution of problems of flow and transport in subsurface geologic media that are addressed by the TOUGH (Pruess et al. 1999) family of codes. MeshVoro, which includes built-in data visualization routines, is a particularly useful tool because it extends the applicability of the TOUGH family of codes by enabling the scientifically robust and relatively easy discretization of systems with challenging 3D geometries. We describe several applications of MeshVoro. We illustrate the ability of the tool to straightforwardly transform a complex geological grid into a simulation mesh that conforms to the specifications of the TOUGH family of codes. We demonstrate how MeshVoro can describe complex system geometries with a relatively small number of grid blocks, and we construct meshes for geometries that would have been practically intractable with a standard Cartesian grid approach. We also discuss the limitations and appropriate applications of this new technology.

  17. SoilGrids1km--global soil information based on automated mapping.

    Directory of Open Access Journals (Sweden)

    Tomislav Hengl

    Full Text Available BACKGROUND: Soils are widely recognized as a non-renewable natural resource and as biophysical carbon sinks. As such, there is a growing requirement for global soil information. Although several global soil information systems already exist, these tend to suffer from inconsistencies and limited spatial detail. METHODOLOGY/PRINCIPAL FINDINGS: We present SoilGrids1km--a global 3D soil information system at 1 km resolution--containing spatial predictions for a selection of soil properties (at six standard depths: soil organic carbon (g kg-1, soil pH, sand, silt and clay fractions (%, bulk density (kg m-3, cation-exchange capacity (cmol+/kg, coarse fragments (%, soil organic carbon stock (t ha-1, depth to bedrock (cm, World Reference Base soil groups, and USDA Soil Taxonomy suborders. Our predictions are based on global spatial prediction models which we fitted, per soil variable, using a compilation of major international soil profile databases (ca. 110,000 soil profiles, and a selection of ca. 75 global environmental covariates representing soil forming factors. Results of regression modeling indicate that the most useful covariates for modeling soils at the global scale are climatic and biomass indices (based on MODIS images, lithology, and taxonomic mapping units derived from conventional soil survey (Harmonized World Soil Database. Prediction accuracies assessed using 5-fold cross-validation were between 23-51%. CONCLUSIONS/SIGNIFICANCE: SoilGrids1km provide an initial set of examples of soil spatial data for input into global models at a resolution and consistency not previously available. Some of the main limitations of the current version of SoilGrids1km are: (1 weak relationships between soil properties/classes and explanatory variables due to scale mismatches, (2 difficulty to obtain covariates that capture soil forming factors, (3 low sampling density and spatial clustering of soil profile locations. However, as the SoilGrids system is

  18. Parallelization of TWOPORFLOW, a Cartesian Grid based Two-phase Porous Media Code for Transient Thermo-hydraulic Simulations

    Science.gov (United States)

    Trost, Nico; Jiménez, Javier; Imke, Uwe; Sanchez, Victor

    2014-06-01

    TWOPORFLOW is a thermo-hydraulic code based on a porous media approach to simulate single- and two-phase flow including boiling. It is under development at the Institute for Neutron Physics and Reactor Technology (INR) at KIT. The code features a 3D transient solution of the mass, momentum and energy conservation equations for two inter-penetrating fluids with a semi-implicit continuous Eulerian type solver. The application domain of TWOPORFLOW includes the flow in standard porous media and in structured porous media such as micro-channels and cores of nuclear power plants. In the latter case, the fluid domain is coupled to a fuel rod model, describing the heat flow inside the solid structure. In this work, detailed profiling tools have been utilized to determine the optimization potential of TWOPORFLOW. As a result, bottle-necks were identified and reduced in the most feasible way, leading for instance to an optimization of the water-steam property computation. Furthermore, an OpenMP implementation addressing the routines in charge of inter-phase momentum-, energy- and mass-coupling delivered good performance together with a high scalability on shared memory architectures. In contrast to that, the approach for distributed memory systems was to solve sub-problems resulting by the decomposition of the initial Cartesian geometry. Thread communication for the sub-problem boundary updates was accomplished by the Message Passing Interface (MPI) standard.

  19. Time-domain analysis of planar microstrip devices using a generalized Yee-algorithm based on unstructured grids

    Science.gov (United States)

    Gedney, Stephen D.; Lansing, Faiza

    1993-01-01

    The generalized Yee-algorithm is presented for the temporal full-wave analysis of planar microstrip devices. This algorithm has the significant advantage over the traditional Yee-algorithm in that it is based on unstructured and irregular grids. The robustness of the generalized Yee-algorithm is that structures that contain curved conductors or complex three-dimensional geometries can be more accurately, and much more conveniently modeled using standard automatic grid generation techniques. This generalized Yee-algorithm is based on the the time-marching solution of the discrete form of Maxwell's equations in their integral form. To this end, the electric and magnetic fields are discretized over a dual, irregular, and unstructured grid. The primary grid is assumed to be composed of general fitted polyhedra distributed throughout the volume. The secondary grid (or dual grid) is built up of the closed polyhedra whose edges connect the centroid's of adjacent primary cells, penetrating shared faces. Faraday's law and Ampere's law are used to update the fields normal to the primary and secondary grid faces, respectively. Subsequently, a correction scheme is introduced to project the normal fields onto the grid edges. It is shown that this scheme is stable, maintains second-order accuracy, and preserves the divergenceless nature of the flux densities. Finally, for computational efficiency the algorithm is structured as a series of sparse matrix-vector multiplications. Based on this scheme, the generalized Yee-algorithm has been implemented on vector and parallel high performance computers in a highly efficient manner.

  20. Porting of Scientific Applications to Grid Computing on GridWay

    Directory of Open Access Journals (Sweden)

    J. Herrera

    2005-01-01

    Full Text Available The expansion and adoption of Grid technologies is prevented by the lack of a standard programming paradigm to port existing applications among different environments. The Distributed Resource Management Application API has been proposed to aid the rapid development and distribution of these applications across different Distributed Resource Management Systems. In this paper we describe an implementation of the DRMAA standard on a Globus-based testbed, and show its suitability to express typical scientific applications, like High-Throughput and Master-Worker applications. The DRMAA routines are supported by the functionality offered by the GridWay2 framework, which provides the runtime mechanisms needed for transparently executing jobs on a dynamic Grid environment based on Globus. As cases of study, we consider the implementation with DRMAA of a bioinformatics application, a genetic algorithm and the NAS Grid Benchmarks.

  1. Air Pollution Monitoring and Mining Based on Sensor Grid in London.

    Science.gov (United States)

    Ma, Yajie; Richards, Mark; Ghanem, Moustafa; Guo, Yike; Hassard, John

    2008-06-01

    In this paper, we present a distributed infrastructure based on wireless sensors network and Grid computing technology for air pollution monitoring and mining, which aims to develop low-cost and ubiquitous sensor networks to collect real-time, large scale and comprehensive environmental data from road traffic emissions for air pollution monitoring in urban environment. The main informatics challenges in respect to constructing the high-throughput sensor Grid are discussed in this paper. We present a twolayer network framework, a P2P e-Science Grid architecture, and the distributed data mining algorithm as the solutions to address the challenges. We simulated the system in TinyOS to examine the operation of each sensor as well as the networking performance. We also present the distributed data mining result to examine the effectiveness of the algorithm.

  2. Grid-based modeling for land use planning and environmental resource mapping.

    Energy Technology Data Exchange (ETDEWEB)

    Kuiper, J. A.

    1999-08-04

    Geographic Information System (GIS) technology is used by land managers and natural resource planners for examining resource distribution and conducting project planning, often by visually interpreting spatial data representing environmental or regulatory variables. Frequently, many variables influence the decision-making process, and modeling can improve results with even a small investment of time and effort. Presented are several grid-based GIS modeling projects, including: (1) land use optimization under environmental and regulatory constraints; (2) identification of suitable wetland mitigation sites; and (3) predictive mapping of prehistoric cultural resource sites. As different as the applications are, each follows a similar process of problem conceptualization, implementation of a practical grid-based GIS model, and evaluation of results.

  3. High-resolution multi-code implementation of unsteady Navier-Stokes flow solver based on paralleled overset adaptive mesh refinement and high-order low-dissipation hybrid schemes

    Science.gov (United States)

    Li, Gaohua; Fu, Xiang; Wang, Fuxin

    2017-10-01

    The low-dissipation high-order accurate hybrid up-winding/central scheme based on fifth-order weighted essentially non-oscillatory (WENO) and sixth-order central schemes, along with the Spalart-Allmaras (SA)-based delayed detached eddy simulation (DDES) turbulence model, and the flow feature-based adaptive mesh refinement (AMR), are implemented into a dual-mesh overset grid infrastructure with parallel computing capabilities, for the purpose of simulating vortex-dominated unsteady detached wake flows with high spatial resolutions. The overset grid assembly (OGA) process based on collection detection theory and implicit hole-cutting algorithm achieves an automatic coupling for the near-body and off-body solvers, and the error-and-try method is used for obtaining a globally balanced load distribution among the composed multiple codes. The results of flows over high Reynolds cylinder and two-bladed helicopter rotor show that the combination of high-order hybrid scheme, advanced turbulence model, and overset adaptive mesh refinement can effectively enhance the spatial resolution for the simulation of turbulent wake eddies.

  4. Application of rule-based data mining techniques to real time ATLAS Grid job monitoring data

    CERN Document Server

    Ahrens, R; The ATLAS collaboration; Kalinin, S; Maettig, P; Sandhoff, M; dos Santos, T; Volkmer, F

    2012-01-01

    The Job Execution Monitor (JEM) is a job-centric grid job monitoring software developed at the University of Wuppertal and integrated into the pilot-based “PanDA” job brokerage system leveraging physics analysis and Monte Carlo event production for the ATLAS experiment on the Worldwide LHC Computing Grid (WLCG). With JEM, job progress and grid worker node health can be supervised in real time by users, site admins and shift personnel. Imminent error conditions can be detected early and countermeasures can be initiated by the Job’s owner immideatly. Grid site admins can access aggregated data of all monitored jobs to infer the site status and to detect job and Grid worker node misbehaviour. Shifters can use the same aggregated data to quickly react to site error conditions and broken production tasks. In this work, the application of novel data-centric rule based methods and data-mining techniques to the real time monitoring data is discussed. The usage of such automatic inference techniques on monitorin...

  5. Beyond grid security

    International Nuclear Information System (INIS)

    Hoeft, B; Epting, U; Koenig, T

    2008-01-01

    While many fields relevant to Grid security are already covered by existing working groups, their remit rarely goes beyond the scope of the Grid infrastructure itself. However, security issues pertaining to the internal set-up of compute centres have at least as much impact on Grid security. Thus, this talk will present briefly the EU ISSeG project (Integrated Site Security for Grids). In contrast to groups such as OSCT (Operational Security Coordination Team) and JSPG (Joint Security Policy Group), the purpose of ISSeG is to provide a holistic approach to security for Grid computer centres, from strategic considerations to an implementation plan and its deployment. The generalised methodology of Integrated Site Security (ISS) is based on the knowledge gained during its implementation at several sites as well as through security audits, and this will be briefly discussed. Several examples of ISS implementation tasks at the Forschungszentrum Karlsruhe will be presented, including segregation of the network for administration and maintenance and the implementation of Application Gateways. Furthermore, the web-based ISSeG training material will be introduced. This aims to offer ISS implementation guidance to other Grid installations in order to help avoid common pitfalls

  6. Flexible operation of parallel grid-connecting converters under unbalanced grid voltage

    DEFF Research Database (Denmark)

    Lu, Jinghang; Savaghebi, Mehdi; Guerrero, Josep M.

    2017-01-01

    -link voltage ripple, and overloading. Moreover, under grid voltage unbalance, the active power delivery ability is decreased due to the converter's current rating limitation. In this paper, a thorough study on the current limitation of the grid-connecting converter under grid voltage unbalance is conducted....... In addition, based on the principle that total output active power should be oscillation free, a coordinated control strategy is proposed for the parallel grid-connecting converters. The case study has been conducted to demonstrate the effectiveness of this proposed control strategy....

  7. Sustainable Power Supply Solutions for Off-Grid Base Stations

    Directory of Open Access Journals (Sweden)

    Asma Mohamad Aris

    2015-09-01

    Full Text Available The telecommunication sector plays a significant role in shaping the global economy and the way people share information and knowledge. At present, the telecommunication sector is liable for its energy consumption and the amount of emissions it emits in the environment. In the context of off-grid telecommunication applications, off-grid base stations (BSs are commonly used due to their ability to provide radio coverage over a wide geographic area. However, in the past, the off-grid BSs usually relied on emission-intensive power supply solutions such as diesel generators. In this review paper, various types of solutions (including, in particular, the sustainable solutions for powering BSs are discussed. The key aspects in designing an ideal power supply solution are reviewed, and these mainly include the pre-feasibility study and the thermal management of BSs, which comprise heating and cooling of the BS shelter/cabinets and BS electronic equipment and power supply components. The sizing and optimization approaches used to design the BSs’ power supply systems as well as the operational and control strategies adopted to manage the power supply systems are also reviewed in this paper.

  8. Facial expression coding in children and adolescents with autism: Reduced adaptability but intact norm-based coding.

    Science.gov (United States)

    Rhodes, Gillian; Burton, Nichola; Jeffery, Linda; Read, Ainsley; Taylor, Libby; Ewing, Louise

    2018-05-01

    Individuals with autism spectrum disorder (ASD) can have difficulty recognizing emotional expressions. Here, we asked whether the underlying perceptual coding of expression is disrupted. Typical individuals code expression relative to a perceptual (average) norm that is continuously updated by experience. This adaptability of face-coding mechanisms has been linked to performance on various face tasks. We used an adaptation aftereffect paradigm to characterize expression coding in children and adolescents with autism. We asked whether face expression coding is less adaptable in autism and whether there is any fundamental disruption of norm-based coding. If expression coding is norm-based, then the face aftereffects should increase with adaptor expression strength (distance from the average expression). We observed this pattern in both autistic and typically developing participants, suggesting that norm-based coding is fundamentally intact in autism. Critically, however, expression aftereffects were reduced in the autism group, indicating that expression-coding mechanisms are less readily tuned by experience. Reduced adaptability has also been reported for coding of face identity and gaze direction. Thus, there appears to be a pervasive lack of adaptability in face-coding mechanisms in autism, which could contribute to face processing and broader social difficulties in the disorder. © 2017 The British Psychological Society.

  9. Bus.py: A GridLAB-D Communication Interface for Smart Distribution Grid Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Timothy M.; Palmintier, Bryan; Suryanarayanan, Siddharth; Maciejewski, Anthony A.; Siegel, Howard Jay

    2015-07-03

    As more Smart Grid technologies (e.g., distributed photovoltaic, spatially distributed electric vehicle charging) are integrated into distribution grids, static distribution simulations are no longer sufficient for performing modeling and analysis. GridLAB-D is an agent-based distribution system simulation environment that allows fine-grained end-user models, including geospatial and network topology detail. A problem exists in that, without outside intervention, once the GridLAB-D simulation begins execution, it will run to completion without allowing the real-time interaction of Smart Grid controls, such as home energy management systems and aggregator control. We address this lack of runtime interaction by designing a flexible communication interface, Bus.py (pronounced bus-dot-pie), that uses Python to pass messages between one or more GridLAB-D instances and a Smart Grid simulator. This work describes the design and implementation of Bus.py, discusses its usefulness in terms of some Smart Grid scenarios, and provides an example of an aggregator-based residential demand response system interacting with GridLAB-D through Bus.py. The small scale example demonstrates the validity of the interface and shows that an aggregator using said interface is able to control residential loads in GridLAB-D during runtime to cause a reduction in the peak load on the distribution system in (a) peak reduction and (b) time-of-use pricing cases.

  10. A composite passive damping method of the LLCL-filter based grid-tied inverter

    DEFF Research Database (Denmark)

    Wu, Weimin; Huang, Min; Sun, Yunjie

    2012-01-01

    This paper investigates the maximum and the minimum gain of the proportional resonant based grid current controller for a grid-tied inverter with a passive damped high-order power filter. It is found that the choice of the controller gain is limited to the local maximum amplitude determined by Q......-factor around the characteristic frequency of the filter and grid impedance. To obtain the Q-factor of a high-order system, an equivalent circuit analysis method is proposed and illustrated through several classical passive damped LCL- and LLCL-filters. It is shown that both the RC parallel damper...... that is in parallel with the capacitor of the LCL-filter or with the Lf-Cf resonant circuit of the LLCL-filter, and the RL series damper in series with the grid-side inductor have their own application limits. Thus, a composite passive damped LLCL-filter for the grid-tied inverter is proposed, which can effectively...

  11. Performance of R-GMA based grid job monitoring system for CMS data production

    CERN Document Server

    Byrom, Robert; Fisher, Steve M; Grandi, Claudio; Hobson, Peter R; Kyberd, Paul; MacEvoy, Barry; Nebrensky, Jindrich Josef; Tallini, Hugh; Traylen, Stephen

    2004-01-01

    High Energy Physics experiments, such as the Compact Muon Solenoid (CMS) at the CERN laboratory in Geneva, have large-scale data processing requirements, with stored data accumulating at a rate of 1 Gbyte/s. This load comfortably exceeds any previous processing requirements and we believe it may be most efficiently satisfied through Grid computing. Management of large Monte Carlo productions (~3000 jobs) or data analyses and the quality assurance of the results requires careful monitoring and bookkeeping, and an important requirement when using the Grid is the ability to monitor transparently the large number of jobs that are being executed simultaneously at multiple remote sites. R-GMA is a monitoring and information management service for distributed resources based on the Grid Monitoring Architecture of the Global Grid Forum. We have previously developed a system allowing us to test its performance under a heavy load while using few real Grid resources. We present the latest results on this system and comp...

  12. A new service-oriented grid-based method for AIoT application and implementation

    Science.gov (United States)

    Zou, Yiqin; Quan, Li

    2017-07-01

    The traditional three-layer Internet of things (IoT) model, which includes physical perception layer, information transferring layer and service application layer, cannot express complexity and diversity in agricultural engineering area completely. It is hard to categorize, organize and manage the agricultural things with these three layers. Based on the above requirements, we propose a new service-oriented grid-based method to set up and build the agricultural IoT. Considering the heterogeneous, limitation, transparency and leveling attributes of agricultural things, we propose an abstract model for all agricultural resources. This model is service-oriented and expressed with Open Grid Services Architecture (OGSA). Information and data of agricultural things were described and encapsulated by using XML in this model. Every agricultural engineering application will provide service by enabling one application node in this service-oriented grid. Description of Web Service Resource Framework (WSRF)-based Agricultural Internet of Things (AIoT) and the encapsulation method were also discussed in this paper for resource management in this model.

  13. Improving energy efficiency and smart grid program analysis with agent-based end-use forecasting models

    International Nuclear Information System (INIS)

    Jackson, Jerry

    2010-01-01

    Electric utilities and regulators face difficult challenges evaluating new energy efficiency and smart grid programs prompted, in large part, by recent state and federal mandates and financial incentives. It is increasingly difficult to separate electricity use impacts of individual utility programs from the impacts of increasingly stringent appliance and building efficiency standards, increasing electricity prices, appliance manufacturer efficiency improvements, energy program interactions and other factors. This study reviews traditional approaches used to evaluate electric utility energy efficiency and smart-grid programs and presents an agent-based end-use modeling approach that resolves many of the shortcomings of traditional approaches. Data for a representative sample of utility customers in a Midwestern US utility are used to evaluate energy efficiency and smart grid program targets over a fifteen-year horizon. Model analysis indicates that a combination of the two least stringent efficiency and smart grid program scenarios provides peak hour reductions one-third greater than the most stringent smart grid program suggesting that reductions in peak demand requirements are more feasible when both efficiency and smart grid programs are considered together. Suggestions on transitioning from traditional end-use models to agent-based end-use models are provided.

  14. 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)

  15. 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).

  16. Power control based on particle swarm optimization of grid-connected inverter for hybrid renewable energy system

    International Nuclear Information System (INIS)

    García-Triviño, Pablo; Gil-Mena, Antonio José; Llorens-Iborra, Francisco; García-Vázquez, Carlos Andrés; Fernández-Ramírez, Luis M.; Jurado, Francisco

    2015-01-01

    Highlights: • Three PSO-based PI controllers for a grid-connected inverter were presented. • Two online PSO-based PI controllers were compared with an offline PSO-tuned PI. • The HRES and the inverter were evaluated under power changes and grid voltage sags. • Online ITAE-based PSO reduced ITAE (current THD) by 15.24% (5.32%) versus offline one. - Abstract: This paper is focused on the study of particle swarm optimization (PSO)-based PI controllers for the power control of a grid-connected inverter supplied from a hybrid renewable energy system. It is composed of two renewable energy sources (wind turbine and photovoltaic – PV – solar panels) and two energy storage systems (battery and hydrogen system, integrated by fuel cell and electrolyzer). Three PSO-based PI controllers are implemented: (1) conventional PI controller with offline tuning by PSO algorithm based on the integral time absolute error (ITAE) index; (2) PI controllers with online self-tuning by PSO algorithm based on the error; and (3) PI controllers with online self-tuning by PSO algorithm based on the ITAE index. To evaluate and compare the three controllers, the hybrid renewable energy system and the grid-connected inverter are simulated under changes in the active and reactive power values, as well as under a grid voltage sag. The results show that the online PSO-based PI controllers that optimize the ITAE index achieves the best response

  17. Application of synchronous grid-connected controller in the wind-solar-storage micro grid

    OpenAIRE

    Li, Hua; Ren, Yongfeng; Li, Le; Luo, Zhenpeng

    2016-01-01

    Recently, there has been an increasing interest in using distributed generators (DG) not only to inject power into the grid, but also to enhance the power quality. In this study, a space voltage pulse width modulation (SVPWM) control method is proposed for a synchronous grid-connected controller in a wind-solar-storage micro grid. This method is based on the appropriate topology of the synchronous controller. The wind-solar-storage micro grid is controlled to reconnect to the grid synchronous...

  18. Small-mammal density estimation: A field comparison of grid-based vs. web-based density estimators

    Science.gov (United States)

    Parmenter, R.R.; Yates, Terry L.; Anderson, D.R.; Burnham, K.P.; Dunnum, J.L.; Franklin, A.B.; Friggens, M.T.; Lubow, B.C.; Miller, M.; Olson, G.S.; Parmenter, Cheryl A.; Pollard, J.; Rexstad, E.; Shenk, T.M.; Stanley, T.R.; White, Gary C.

    2003-01-01

    blind” test allowed us to evaluate the influence of expertise and experience in calculating density estimates in comparison to simply using default values in programs CAPTURE and DISTANCE. While the rodent sample sizes were considerably smaller than the recommended minimum for good model results, we found that several models performed well empirically, including the web-based uniform and half-normal models in program DISTANCE, and the grid-based models Mb and Mbh in program CAPTURE (with AÌ‚ adjusted by species-specific full mean maximum distance moved (MMDM) values). These models produced accurate DÌ‚ values (with 95% confidence intervals that included the true D values) and exhibited acceptable bias but poor precision. However, in linear regression analyses comparing each model's DÌ‚ values to the true D values over the range of observed test densities, only the web-based uniform model exhibited a regression slope near 1.0; all other models showed substantial slope deviations, indicating biased estimates at higher or lower density values. In addition, the grid-based DÌ‚ analyses using full MMDM values for WÌ‚ area adjustments required a number of theoretical assumptions of uncertain validity, and we therefore viewed their empirical successes with caution. Finally, density estimates from the independent analysts were highly variable, but estimates from web-based approaches had smaller mean square errors and better achieved confidence-interval coverage of D than did grid-based approaches. Our results support the contention that web-based approaches for density estimation of small-mammal populations are both theoretically and empirically superior to grid-based approaches, even when sample size is far less than often recommended. In view of the increasing need for standardized environmental measures for comparisons among ecosystems and through time, analytical models based on distance sampling appear to offer accurate density estimation approaches for research

  19. SHOP: scaffold hopping by GRID-based similarity searches

    DEFF Research Database (Denmark)

    Bergmann, Rikke; Linusson, Anna; Zamora, Ismael

    2007-01-01

    A new GRID-based method for scaffold hopping (SHOP) is presented. In a fully automatic manner, scaffolds were identified in a database based on three types of 3D-descriptors. SHOP's ability to recover scaffolds was assessed and validated by searching a database spiked with fragments of known...... scaffolds were in the 31 top-ranked scaffolds. SHOP also identified new scaffolds with substantially different chemotypes from the queries. Docking analysis indicated that the new scaffolds would have similar binding modes to those of the respective query scaffolds observed in X-ray structures...

  20. A Fokker-Planck-Landau collision equation solver on two-dimensional velocity grid and its application to particle-in-cell simulation

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, E. S.; Chang, C. S., E-mail: cschang@pppl.gov [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Korea Advanced Institute of Science and Technology, Yuseong-gu, DaeJeon 305-701 (Korea, Republic of)

    2014-03-15

    An approximate two-dimensional solver of the nonlinear Fokker-Planck-Landau collision operator has been developed using the assumption that the particle probability distribution function is independent of gyroangle in the limit of strong magnetic field. The isotropic one-dimensional scheme developed for nonlinear Fokker-Planck-Landau equation by Buet and Cordier [J. Comput. Phys. 179, 43 (2002)] and for linear Fokker-Planck-Landau equation by Chang and Cooper [J. Comput. Phys. 6, 1 (1970)] have been modified and extended to two-dimensional nonlinear equation. In addition, a method is suggested to apply the new velocity-grid based collision solver to Lagrangian particle-in-cell simulation by adjusting the weights of marker particles and is applied to a five dimensional particle-in-cell code to calculate the neoclassical ion thermal conductivity in a tokamak plasma. Error verifications show practical aspects of the present scheme for both grid-based and particle-based kinetic codes.

  1. Active Power Quality Improvement Strategy for Grid-connected Microgrid Based on Hierarchical Control

    DEFF Research Database (Denmark)

    Wei, Feng; Sun, Kai; Guan, Yajuan

    2018-01-01

    proposes an active, unbalanced, and harmonic GCC suppression strategy based on hierarchical theory. The voltage error between the bus of the DCGC-MG and the grid’s PCC was transformed to the dq frame. On the basis of the grid, an additional compensator, which consists of multiple resonant voltage......When connected to a distorted grid utility, droop-controlled grid-connected microgrids (DCGC-MG) exhibit low equivalent impedance. The harmonic and unbalanced voltage at the point of common coupling (PCC) deteriorates the power quality of the grid-connected current (GCC) of DCGC-MG. This work...... regulators, was then added to the original secondary control to generate the negative fundamental and unbalanced harmonic voltage reference. Proportional integral and multiple resonant controllers were adopted as voltage controller at the original primary level to improve the voltage tracking performance...

  2. Operation of an InGrid based X-ray detector at the CAST experiment

    Directory of Open Access Journals (Sweden)

    Krieger Christoph

    2018-01-01

    During operation at the experiment, background rates in the order of 10−5 keV−1 cm−2 s−1 have been achieved by application of a likelihood based method discriminating the non-photon background originating mostly from cosmic rays. For continued operation in 2016, an upgraded InGrid based detector is to be installed among other improvements including decoupling and sampling of the signal induced on the grid as well as a veto scintillator to further lower the observed background rates and improving sensitivity.

  3. State of art in FE-based fuel performance codes

    International Nuclear Information System (INIS)

    Kim, Hyo Chan; Yang, Yong Sik; Kim, Dae Ho; Bang, Je Geon; Kim, Sun Ki; Koo, Yang Hyun

    2013-01-01

    Finite element (FE) method that is reliable and proven solution in mechanical field has been introduced into fuel performance codes for multidimensional analysis. The present state of the art in numerical simulation of FE-based fuel performance predominantly involves 2-D axisymmetric model and 3-D volumetric model. The FRAPCON and FRAPTRAN own 1.5-D and 2-D FE model to simulate PCMI and cladding ballooning. In 2-D simulation, the FALCON code, developed by EPRI, is a 2-D (R-Z and R-θ) fully thermal-mechanically coupled steady-state and transient FE-based fuel behavior code. The French codes TOUTATIS and ALCYONE which are 3-D, and typically used to investigate localized behavior. In 2008, the Idaho National Laboratory (INL) has been developing multidimensional (2-D and 3-D) nuclear fuel performance code called BISON. In this paper, the current state of FE-based fuel performance code and their models are presented. Based on investigation into the codes, requirements and direction of development for new FE-based fuel performance code can be discussed. Based on comparison of models in FE-based fuel performance code, status of art in the codes can be discussed. A new FE-based fuel performance code should include typical pellet and cladding models which all codes own. In particular, specified pellet and cladding model such as gaseous swelling and high burnup structure (HBS) model should be developed to improve accuracy of code as well as consider AC condition. To reduce computation cost, the approximated gap and the optimized contact model should be also developed. Nuclear fuel operates in an extreme environment that induces complex multiphysics phenomena, occurring over distances ranging from inter-atomic spacing to meters, and times scales ranging from microseconds to years. This multiphysics behavior is often tightly coupled, a well known example being the thermomechanical behavior. Adding to this complexity, important aspects of fuel behavior are inherently

  4. Air Pollution Monitoring and Mining Based on Sensor Grid in London

    Science.gov (United States)

    Ma, Yajie; Richards, Mark; Ghanem, Moustafa; Guo, Yike; Hassard, John

    2008-01-01

    In this paper, we present a distributed infrastructure based on wireless sensors network and Grid computing technology for air pollution monitoring and mining, which aims to develop low-cost and ubiquitous sensor networks to collect real-time, large scale and comprehensive environmental data from road traffic emissions for air pollution monitoring in urban environment. The main informatics challenges in respect to constructing the high-throughput sensor Grid are discussed in this paper. We present a two-layer network framework, a P2P e-Science Grid architecture, and the distributed data mining algorithm as the solutions to address the challenges. We simulated the system in TinyOS to examine the operation of each sensor as well as the networking performance. We also present the distributed data mining result to examine the effectiveness of the algorithm. PMID:27879895

  5. Air Pollution Monitoring and Mining Based on Sensor Grid in London

    Directory of Open Access Journals (Sweden)

    John Hassard

    2008-06-01

    Full Text Available In this paper, we present a distributed infrastructure based on wireless sensors network and Grid computing technology for air pollution monitoring and mining, which aims to develop low-cost and ubiquitous sensor networks to collect real-time, large scale and comprehensive environmental data from road traffic emissions for air pollution monitoring in urban environment. The main informatics challenges in respect to constructing the high-throughput sensor Grid are discussed in this paper. We present a twolayer network framework, a P2P e-Science Grid architecture, and the distributed data mining algorithm as the solutions to address the challenges. We simulated the system in TinyOS to examine the operation of each sensor as well as the networking performance. We also present the distributed data mining result to examine the effectiveness of the algorithm.

  6. Incorporating Code-Based Software in an Introductory Statistics Course

    Science.gov (United States)

    Doehler, Kirsten; Taylor, Laura

    2015-01-01

    This article is based on the experiences of two statistics professors who have taught students to write and effectively utilize code-based software in a college-level introductory statistics course. Advantages of using software and code-based software in this context are discussed. Suggestions are made on how to ease students into using code with…

  7. Indonesia - Green Prosperity: Community-Based Off-Grid Renewable Energy Grant Portfolio

    Data.gov (United States)

    Millennium Challenge Corporation — Taken as a whole, this evaluation aims, to the extent possible, to validate the program logic underlying the portfolio of community-based off-grid renewable energy...

  8. Implementation of LT codes based on chaos

    International Nuclear Information System (INIS)

    Zhou Qian; Li Liang; Chen Zengqiang; Zhao Jiaxiang

    2008-01-01

    Fountain codes provide an efficient way to transfer information over erasure channels like the Internet. LT codes are the first codes fully realizing the digital fountain concept. They are asymptotically optimal rateless erasure codes with highly efficient encoding and decoding algorithms. In theory, for each encoding symbol of LT codes, its degree is randomly chosen according to a predetermined degree distribution, and its neighbours used to generate that encoding symbol are chosen uniformly at random. Practical implementation of LT codes usually realizes the randomness through pseudo-randomness number generator like linear congruential method. This paper applies the pseudo-randomness of chaotic sequence in the implementation of LT codes. Two Kent chaotic maps are used to determine the degree and neighbour(s) of each encoding symbol. It is shown that the implemented LT codes based on chaos perform better than the LT codes implemented by the traditional pseudo-randomness number generator. (general)

  9. New 2D adaptive mesh refinement algorithm based on conservative finite-differences with staggered grid

    Science.gov (United States)

    Gerya, T.; Duretz, T.; May, D. A.

    2012-04-01

    We present new 2D adaptive mesh refinement (AMR) algorithm based on stress-conservative finite-differences formulated for non-uniform rectangular staggered grid. The refinement approach is based on a repetitive cell splitting organized via a quad-tree construction (every parent cell is split into 4 daughter cells of equal size). Irrespective of the level of resolution every cell has 5 staggered nodes (2 horizontal velocities, 2 vertical velocities and 1 pressure) for which respective governing equations, boundary conditions and interpolation equations are formulated. The connectivity of the grid is achieved via cross-indexing of grid cells and basic nodal points located in their corners: four corner nodes are indexed for every cell and up to 4 surrounding cells are indexed for every node. The accuracy of the approach depends critically on the formulation of the stencil used at the "hanging" velocity nodes located at the boundaries between different levels of resolution. Most accurate results are obtained for the scheme based on the volume flux balance across the resolution boundary combined with stress-based interpolation of velocity orthogonal to the boundary. We tested this new approach with a number of 2D variable viscosity analytical solutions. Our tests demonstrate that the adaptive staggered grid formulation has convergence properties similar to those obtained in case of a standard, non-adaptive staggered grid formulation. This convergence is also achieved when resolution boundary crosses sharp viscosity contrast interfaces. The convergence rates measured are found to be insensitive to scenarios when the transition in grid resolution crosses sharp viscosity contrast interfaces. We compared various grid refinement strategies based on distribution of different field variables such as viscosity, density and velocity. According to these tests the refinement allows for significant (0.5-1 order of magnitude) increase in the computational accuracy at the same

  10. A progressive data compression scheme based upon adaptive transform coding: Mixture block coding of natural images

    Science.gov (United States)

    Rost, Martin C.; Sayood, Khalid

    1991-01-01

    A method for efficiently coding natural images using a vector-quantized variable-blocksized transform source coder is presented. The method, mixture block coding (MBC), incorporates variable-rate coding by using a mixture of discrete cosine transform (DCT) source coders. Which coders are selected to code any given image region is made through a threshold driven distortion criterion. In this paper, MBC is used in two different applications. The base method is concerned with single-pass low-rate image data compression. The second is a natural extension of the base method which allows for low-rate progressive transmission (PT). Since the base method adapts easily to progressive coding, it offers the aesthetic advantage of progressive coding without incorporating extensive channel overhead. Image compression rates of approximately 0.5 bit/pel are demonstrated for both monochrome and color images.

  11. Research and design of smart grid monitoring control via terminal based on iOS system

    Science.gov (United States)

    Fu, Wei; Gong, Li; Chen, Heli; Pan, Guangji

    2017-06-01

    Aiming at a series of problems existing in current smart grid monitoring Control Terminal, such as high costs, poor portability, simple monitoring system, poor software extensions, low system reliability when transmitting information, single man-machine interface, poor security, etc., smart grid remote monitoring system based on the iOS system has been designed. The system interacts with smart grid server so that it can acquire grid data through WiFi/3G/4G networks, and monitor each grid line running status, as well as power plant equipment operating conditions. When it occurs an exception in the power plant, incident information can be sent to the user iOS terminal equipment timely, which will provide troubleshooting information to help the grid staff to make the right decisions in a timely manner, to avoid further accidents. Field tests have shown the system realizes the integrated grid monitoring functions, low maintenance cost, friendly interface, high security and reliability, and it possesses certain applicable value.

  12. A Synchronization Method for Single-Phase Grid-Tied Inverters

    DEFF Research Database (Denmark)

    Hadjidemetriou, Lenos; Kyriakides, Elias; Yang, Yongheng

    2016-01-01

    The controllers of single-phase grid-tied inverters require improvements to enable distribution generation systems to meet the grid codes/standards with respect to power quality and the fault ride through capability. In that case, the response of the selected synchronization technique is crucial...... for the performance of the entire grid-tied inverter. In this paper, a new synchronization method with good dynamics and high accuracy under a highly distorted voltage is proposed. This method uses a Multi-Harmonic Decoupling Cell (MHDC), which thus can cancel out the oscillations on the synchronization signals due...... to the harmonic voltage distortion while maintaining the dynamic response of the synchronization. Therefore, the accurate and dynamic response of the proposed MHDC-PLL can be beneficial for the performance of the whole single-phase grid-tied inverter....

  13. A comparative analysis of dynamic grids vs. virtual grids using the A3pviGrid framework.

    Science.gov (United States)

    Shankaranarayanan, Avinas; Amaldas, Christine

    2010-11-01

    With the proliferation of Quad/Multi-core micro-processors in mainstream platforms such as desktops and workstations; a large number of unused CPU cycles can be utilized for running virtual machines (VMs) as dynamic nodes in distributed environments. Grid services and its service oriented business broker now termed cloud computing could deploy image based virtualization platforms enabling agent based resource management and dynamic fault management. In this paper we present an efficient way of utilizing heterogeneous virtual machines on idle desktops as an environment for consumption of high performance grid services. Spurious and exponential increases in the size of the datasets are constant concerns in medical and pharmaceutical industries due to the constant discovery and publication of large sequence databases. Traditional algorithms are not modeled at handing large data sizes under sudden and dynamic changes in the execution environment as previously discussed. This research was undertaken to compare our previous results with running the same test dataset with that of a virtual Grid platform using virtual machines (Virtualization). The implemented architecture, A3pviGrid utilizes game theoretic optimization and agent based team formation (Coalition) algorithms to improve upon scalability with respect to team formation. Due to the dynamic nature of distributed systems (as discussed in our previous work) all interactions were made local within a team transparently. This paper is a proof of concept of an experimental mini-Grid test-bed compared to running the platform on local virtual machines on a local test cluster. This was done to give every agent its own execution platform enabling anonymity and better control of the dynamic environmental parameters. We also analyze performance and scalability of Blast in a multiple virtual node setup and present our findings. This paper is an extension of our previous research on improving the BLAST application framework

  14. Trends in life science grid: from computing grid to knowledge grid

    Directory of Open Access Journals (Sweden)

    Konagaya Akihiko

    2006-12-01

    Full Text Available Abstract Background Grid computing has great potential to become a standard cyberinfrastructure for life sciences which often require high-performance computing and large data handling which exceeds the computing capacity of a single institution. Results This survey reviews the latest grid technologies from the viewpoints of computing grid, data grid and knowledge grid. Computing grid technologies have been matured enough to solve high-throughput real-world life scientific problems. Data grid technologies are strong candidates for realizing "resourceome" for bioinformatics. Knowledge grids should be designed not only from sharing explicit knowledge on computers but also from community formulation for sharing tacit knowledge among a community. Conclusion Extending the concept of grid from computing grid to knowledge grid, it is possible to make use of a grid as not only sharable computing resources, but also as time and place in which people work together, create knowledge, and share knowledge and experiences in a community.

  15. Smart Solar Grid. Integration of high penetration of photovoltaic in municipal low voltage distribution grids; Smart Solar Grid. Integration hoher Anteile von Photovoltaik in kommunalen Niederspannungsverteilnetzen

    Energy Technology Data Exchange (ETDEWEB)

    Ruf, Holger; Heilscher, Gerd [Hochschule Ulm (Germany); Meier, Florian [SWU Netze GmbH, Ulm (Germany)

    2012-07-01

    The high rate of decentralized generation in low voltage grids especially photovoltaic (PV) put the distribution grid operators to new challenges. Grid operation and grid planning have to respect the volatility and dynamic of decentralized generation now and in the future and adapt their previous proceedings. In the frame of the project Smart Solar Grid was a test site defined in the grid area of the DSO Stadtwerke Ulm/Neu-Ulm GmbH (SWU) to analyze the impact of the PV rise and possible solutions for the grid planning in the future. The first analysis based upon secondly measurements of the first test site. From this were statistical evaluation of the load flows and power variations done. Furthermore were the roof potential analysis results of the test site validated. These data are the base for the development of a forecast system for grid condition parameter. (orig.)

  16. Micro grids toward the smart grid

    International Nuclear Information System (INIS)

    Guerrero, J.

    2011-01-01

    Worldwide electrical grids are expecting to become smarter in the near future, with interest in Microgrids likely to grow. A microgrid can be defined as a part of the grid with elements of prime energy movers, power electronics converters, distributed energy storage systems and local loads, that can operate autonomously but also interacting with main grid. Thus, the ability of intelligent Microgrids to operate in island mode or connected to the grid will be a keypoint to cope with new functionalities and the integration of renewable energy resources. The functionalities expected for these small grids are: black start operation, frequency and voltage stability, active and reactive power flow control, active power filter capabilities, and storage energy management. In this presentation, a review of the main concepts related to flexible Microgrids will be introduced, with examples of real Microgrids. AC and DC Microgrids to integrate renewable and distributed energy resources will also be presented, as well as distributed energy storage systems, and standardization issues of these Microgrids. Finally, Microgrid hierarchical control will be analyzed looking at three different levels: i) a primary control based on the droop method, including an output impedance virtual loop; ii) a secondary control, which enables restoring any deviations produced by the primary control; and iii) a tertiary control to manage the power flow between the microgrid and the external electrical distribution system.

  17. Modelling security properties in a grid-based operating system with anti-goals

    OpenAIRE

    Arenas, A.; Aziz, Benjamin; Bicarregui, J.; Matthews, B.; Yang, E.

    2008-01-01

    In this paper, we discuss the use of formal requirements-engineering techniques in capturing security requirements for a Grid-based operating system. We use KAOS goal model to represent two security goals for Grid systems, namely authorisation and single-sign on authentication. We apply goal-refinement to derive security requirements for these two security goals and we develop a model of antigoals and show how system vulnerabilities and threats to the security goals can arise from such anti-m...

  18. Application of the FUN3D Unstructured-Grid Navier-Stokes Solver to the 4th AIAA Drag Prediction Workshop Cases

    Science.gov (United States)

    Lee-Rausch, Elizabeth M.; Hammond, Dana P.; Nielsen, Eric J.; Pirzadeh, S. Z.; Rumsey, Christopher L.

    2010-01-01

    FUN3D Navier-Stokes solutions were computed for the 4th AIAA Drag Prediction Workshop grid convergence study, downwash study, and Reynolds number study on a set of node-based mixed-element grids. All of the baseline tetrahedral grids were generated with the VGRID (developmental) advancing-layer and advancing-front grid generation software package following the gridding guidelines developed for the workshop. With maximum grid sizes exceeding 100 million nodes, the grid convergence study was particularly challenging for the node-based unstructured grid generators and flow solvers. At the time of the workshop, the super-fine grid with 105 million nodes and 600 million elements was the largest grid known to have been generated using VGRID. FUN3D Version 11.0 has a completely new pre- and post-processing paradigm that has been incorporated directly into the solver and functions entirely in a parallel, distributed memory environment. This feature allowed for practical pre-processing and solution times on the largest unstructured-grid size requested for the workshop. For the constant-lift grid convergence case, the convergence of total drag is approximately second-order on the finest three grids. The variation in total drag between the finest two grids is only 2 counts. At the finest grid levels, only small variations in wing and tail pressure distributions are seen with grid refinement. Similarly, a small wing side-of-body separation also shows little variation at the finest grid levels. Overall, the FUN3D results compare well with the structured-grid code CFL3D. The FUN3D downwash study and Reynolds number study results compare well with the range of results shown in the workshop presentations.

  19. Grid-based virtual clinic for medical diagnosis tutoring | Yatchou ...

    African Journals Online (AJOL)

    La réalisation visée est un outil collaboratif d\\'enseignement pour les médecins du terrain et les étudiants en médecine au sein d\\'une organisation virtuelle. The emerging grid-based technologies are increasingly adopted to enhance education and provide better learning services. This is characterized all over the world, ...

  20. Thyristor based short circuit current injection in isolated grids

    OpenAIRE

    Hoff, Bjarte; Sharma, Pawan; Østrem, Trond

    2017-01-01

    This paper proposes a thyristor based short circuit current injector for providing short circuit current in isolated and weak grids, where sufficient fault current to trigger circuit breakers may not be available. This will allow the use of conventional miniature circuit breakers, which requires high fault current for instantaneous tripping. The method has been validated through experiments.

  1. Non-Binary Protograph-Based LDPC Codes: Analysis,Enumerators and Designs

    OpenAIRE

    Sun, Yizeng

    2013-01-01

    Non-binary LDPC codes can outperform binary LDPC codes using sum-product algorithm with higher computation complexity. Non-binary LDPC codes based on protographs have the advantage of simple hardware architecture. In the first part of this thesis, we will use EXIT chart analysis to compute the thresholds of different protographs over GF(q). Based on threshold computation, some non-binary protograph-based LDPC codes are designed and their frame error rates are compared with binary LDPC codes. ...

  2. Grid interoperability: joining grid information systems

    International Nuclear Information System (INIS)

    Flechl, M; Field, L

    2008-01-01

    A grid is defined as being 'coordinated resource sharing and problem solving in dynamic, multi-institutional virtual organizations'. Over recent years a number of grid projects, many of which have a strong regional presence, have emerged to help coordinate institutions and enable grids. Today, we face a situation where a number of grid projects exist, most of which are using slightly different middleware. Grid interoperation is trying to bridge these differences and enable Virtual Organizations to access resources at the institutions independent of their grid project affiliation. Grid interoperation is usually a bilateral activity between two grid infrastructures. Recently within the Open Grid Forum, the Grid Interoperability Now (GIN) Community Group is trying to build upon these bilateral activities. The GIN group is a focal point where all the infrastructures can come together to share ideas and experiences on grid interoperation. It is hoped that each bilateral activity will bring us one step closer to the overall goal of a uniform grid landscape. A fundamental aspect of a grid is the information system, which is used to find available grid services. As different grids use different information systems, interoperation between these systems is crucial for grid interoperability. This paper describes the work carried out to overcome these differences between a number of grid projects and the experiences gained. It focuses on the different techniques used and highlights the important areas for future standardization

  3. A Generic Danish Distribution Grid Model for Smart Grid Technology Testing

    DEFF Research Database (Denmark)

    Cha, Seung-Tae; Wu, Qiuwei; Østergaard, Jacob

    2012-01-01

    This paper describes the development of a generic Danish distribution grid model for smart grid technology testing based on the Bornholm power system. The frequency dependent network equivalent (FDNE) method has been used in order to accurately preserve the desired properties and characteristics...... as a generic Smart Grid benchmark model for testing purposes....... by comparing the transient response of the original Bornholm power system model and the developed generic model under significant fault conditions. The results clearly show that the equivalent generic distribution grid model retains the dynamic characteristics of the original system, and can be used...

  4. A Novel Quad Harmony Search Algorithm for Grid-Based Path Finding

    Directory of Open Access Journals (Sweden)

    Saso Koceski

    2014-09-01

    Full Text Available A novel approach to the problem of grid-based path finding has been introduced. The method is a block-based search algorithm, founded on the bases of two algorithms, namely the quad-tree algorithm, which offered a great opportunity for decreasing the time needed to compute the solution, and the harmony search (HS algorithm, a meta-heuristic algorithm used to obtain the optimal solution. This quad HS algorithm uses the quad-tree decomposition of free space in the grid to mark the free areas and treat them as a single node, which greatly improves the execution. The results of the quad HS algorithm have been compared to other meta-heuristic algorithms, i.e., ant colony, genetic algorithm, particle swarm optimization and simulated annealing, and it was proved to obtain the best results in terms of time and giving the optimal path.

  5. Four year-olds use norm-based coding for face identity.

    Science.gov (United States)

    Jeffery, Linda; Read, Ainsley; Rhodes, Gillian

    2013-05-01

    Norm-based coding, in which faces are coded as deviations from an average face, is an efficient way of coding visual patterns that share a common structure and must be distinguished by subtle variations that define individuals. Adults and school-aged children use norm-based coding for face identity but it is not yet known if pre-school aged children also use norm-based coding. We reasoned that the transition to school could be critical in developing a norm-based system because school places new demands on children's face identification skills and substantially increases experience with faces. Consistent with this view, face identification performance improves steeply between ages 4 and 7. We used face identity aftereffects to test whether norm-based coding emerges between these ages. We found that 4 year-old children, like adults, showed larger face identity aftereffects for adaptors far from the average than for adaptors closer to the average, consistent with use of norm-based coding. We conclude that experience prior to age 4 is sufficient to develop a norm-based face-space and that failure to use norm-based coding cannot explain 4 year-old children's poor face identification skills. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Measurement and model development of the droplet diameter in rod bundles with spacer grids in the reactor core

    Energy Technology Data Exchange (ETDEWEB)

    No, Hee Cheon; Lee, Eo Hwak; Yoo, Seung Hun; Jin, Hyung Gon; Kim, In Hun [KAIST, Daejeon (Korea, Republic of)

    2010-05-15

    To understand and to predict the heat transfer between superheated steam and droplets properly during reflood phase of LBLOCA of APR1400, it is very important to measure broken droplet sizes by spacer grids. A study, therefore, has been performed to investigate droplet size in rod bundles with spacer grids and to develop a spacer grid droplet size model for safety analysis codes. Experiments were conducted with liquid droplets (SMD of 300{approx}700 {mu}m) impacting on various spacer grids at air superficial velocity of 10 and 20 m/s based on FLECHT SEASET. The test channel and the grids were heated to 150 .deg. C to prevent the formation of liquid film during tests. The spacer grids were designed refer to the Korean fuel rod bundles (Korean Standard Fuel, Plus 7) of APR1400 with various blockage area ratio and grid geometries (strap thickness, mixing vane) and about 15,000 droplets were measured at upstream and downstream of the grids in 16 tests. As a result, the measurement of broken droplet size by spacer grids with photography method is presented and the droplet size model related to spacer grids as a function of blockage area ratio is suggested in this report

  7. Phase-lock loop of Grid-connected Voltage Source Converter under non-ideal grid condition

    DEFF Research Database (Denmark)

    Wang, Haojie; Sun, Hai; Han, Minxiao

    2015-01-01

    It is a normal practice that the DC micro-grid is connected to AC main grid through Grid-connected Voltage Source Converter (G-VSC) for voltage support. Accurate control of DC micro-grid voltage is difficult for G-VSC under unbalanced grid condition as the fundamental positive-sequence component...... and distorted system voltage the proposed PLL can accurately detect the fundamental positive-sequence component of grid voltage thus accurate control of DC micro-grid voltage can be realized....... phase information cannot be accurately tracked. Based on analysis of the cause of double-frequency ripple when unbalance exists in main grid, a phase-locked loop (PLL) detection technique is proposed. Under the conditions of unsymmetrical system voltage, varying system frequency, single-phase system...

  8. Zircaloy spacer grid for boiling light water reactors

    International Nuclear Information System (INIS)

    Borgiani, F.; Cali', G.P.; Cerretti, P.; Pazzo, P.

    1975-01-01

    The need to increase the neutronic efficiency of the new cores of BWR's, lead to study types of spacer-grids made of low neutronic absorption materials as zircaloy-4. The particular mechanical behaviour of this material suggested to design a spacer-grids such as to utilize only blanking, slotting and bending operations as plastic forming and to avoid therefore drawing effects. The optimization of the bending procedures lead to a final spacer-grids configuration equally stiff in all directions and planes. Only for the ''elastic constraints'' nichel alloy sheets were used to made easy the whole spacer design. The ''rigid constraints'', supporting the rods, have been obtained directly from the spacer structure. Calculations were performed to verify the mechanical strength of the main grid components. In this framework a computer code was developed to find the best elastic characteristic of the ''elastic constraints'' taking into account the machining tolerances. Some original methods to test the integral behaviour of the grid assembled as well as the procedures to be adopted for its best maintenance, are described

  9. A New Family of Multilevel Grid Connected Inverters Based on Packed U Cell Topology.

    Science.gov (United States)

    Pakdel, Majid; Jalilzadeh, Saeid

    2017-09-29

    In this paper a novel packed U cell (PUC) based multilevel grid connected inverter is proposed. Unlike the U cell arrangement which consists of two power switches and one capacitor, in the proposed converter topology a lower DC power supply from renewable energy resources such as photovoltaic arrays (PV) is used as a base power source. The proposed topology offers higher efficiency and lower cost using a small number of power switches and a lower DC power source which is supplied from renewable energy resources. Other capacitor voltages are extracted from the base lower DC power source using isolated DC-DC power converters. The operation principle of proposed transformerless multilevel grid connected inverter is analyzed theoretically. Operation of the proposed multilevel grid connected inverter is verified through simulation studies. An experimental prototype using STM32F407 discovery controller board is performed to verify the simulation results.

  10. Task 5. Grid interconnection of building integrated and other dispersed photovoltaic power systems. International guideline for the certification of photovoltaic system components and grid-connected systems

    Energy Technology Data Exchange (ETDEWEB)

    Bower, W.

    2002-02-15

    This report for the International Energy Agency (IEA) made by Task 5 of the Photovoltaic Power Systems (PVPS) programme presents a guideline for the certification of photovoltaic system components and grid-connected systems. The mission of the Photovoltaic Power Systems Programme is to enhance the international collaboration efforts which accelerate the development and deployment of photovoltaic solar energy. Task 5 deals with issues concerning grid-interconnection and distributed PV power systems. This generic international guideline for the certification of photovoltaic system components and complete grid-connected photovoltaic systems describes a set of recommended methods and tests that may be used to verify the integrity of hardware and installations, compliance with applicable standards/codes and can be used to provide a measure of the performance of components or of entire systems. The guideline is to help ensure that photovoltaic installations are both safe for equipment as well as for personnel when used according to the applicable installation standards and codes. The guideline may be used in any country using the rules stipulated by the applicable standards and codes and by applying them to the guideline's recommended tests. This document uses examples for some tests but does not specify exact test set-ups, equipment accuracy, equipment manufacturers or calibration procedures.

  11. Volttron: An Agent Platform for the Smart Grid

    Energy Technology Data Exchange (ETDEWEB)

    Haack, Jereme N.; Akyol, Bora A.; Carpenter, Brandon J.; Tews, Cody W.; Foglesong, Lance W.

    2013-05-06

    VOLLTRON platform enables the deployment of intelligent sensors and controllers in the smart grid and provides a stable, secure and flexible framework that expands the sensing and control capabilities. VOLTTRON platform provides services fulfilling the essential requirements of resource management and security for agent operation in the power grid. The facilities provided by the platform allow agent developers to focus on the implementation of their agent system and not on the necessary "plumbing' code. For example, a simple collaborative demand response application was written in less than 200 lines of Python.

  12. Neighboring Structure Visualization on a Grid-based Layout.

    Science.gov (United States)

    Marcou, G; Horvath, D; Varnek, A

    2017-10-01

    Here, we describe an algorithm to visualize chemical structures on a grid-based layout in such a way that similar structures are neighboring. It is based on structure reordering with the help of the Hilbert Schmidt Independence Criterion, representing an empirical estimate of the Hilbert-Schmidt norm of the cross-covariance operator. The method can be applied to any layout of bi- or three-dimensional shape. The approach is demonstrated on a set of dopamine D5 ligands visualized on squared, disk and spherical layouts. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Silicon-based metallic micro grid for electron field emission

    International Nuclear Information System (INIS)

    Kim, Jaehong; Jeon, Seok-Gy; Kim, Jung-Il; Kim, Geun-Ju; Heo, Duchang; Shin, Dong Hoon; Sun, Yuning; Lee, Cheol Jin

    2012-01-01

    A micro-scale metal grid based on a silicon frame for application to electron field emission devices is introduced and experimentally demonstrated. A silicon lattice containing aperture holes with an area of 80 × 80 µm 2 and a thickness of 10 µm is precisely manufactured by dry etching the silicon on one side of a double-polished silicon wafer and by wet etching the opposite side. Because a silicon lattice is more rigid than a pure metal lattice, a thin layer of Au/Ti deposited on the silicon lattice for voltage application can be more resistant to the geometric stress caused by the applied electric field. The micro-fabrication process, the images of the fabricated grid with 88% geometric transparency and the surface profile measurement after thermal feasibility testing up to 700 °C are presented. (paper)

  14. Grid-enabled SEE++, A Grid-Based Medical Decision Support System for Eye Muscle Surgery Conference

    CERN Document Server

    Schreiner, W.; Buchberger, M.; Kaltofen, T.

    2006-01-01

    JKU/RISC currently develops in cooperation with Upper Austrian Research (UAR) the SEE-GRID software system. SEE-GRID is based on the SEE++ software for the biomechanical 3D simulation of the human eye and its muscles. SEE++ simulates the common eye muscle surgery techniques in a graphic interactive way that is familiar to an experienced surgeon. SEE++ is world-wide the most advanced software for this purpose; it is used by various hospitals and medical doctors for surgery training and planning, SEE++ deals with the support of diagnosis and treatment of strabismus, which is the common name given to usually persistent or regularly occuring misalignment of the eyes. Strabismus is a visual defect in which eyes point in different directions. A person suffering from it may see double images due to misaligned eyes. SEE++ is able to simulate the result of the Hess-Lancaster test, from which the pathological reason of strabismus can be estimated. The outcome of such an examination is two gaze patterns of blue points a...

  15. A framework supporting the development of a Grid portal for analysis based on ROI.

    Science.gov (United States)

    Ichikawa, K; Date, S; Kaishima, T; Shimojo, S

    2005-01-01

    In our research on brain function analysis, users require two different simultaneous types of processing: interactive processing to a specific part of data and high-performance batch processing to an entire dataset. The difference between these two types of processing is in whether or not the analysis is for data in the region of interest (ROI). In this study, we propose a Grid portal that has a mechanism to freely assign computing resources to the users on a Grid environment according to the users' two different types of processing requirements. We constructed a Grid portal which integrates interactive processing and batch processing by the following two mechanisms. First, a job steering mechanism controls job execution based on user-tagged priority among organizations with heterogeneous computing resources. Interactive jobs are processed in preference to batch jobs by this mechanism. Second, a priority-based result delivery mechanism that administrates a rank of data significance. The portal ensures a turn-around time of interactive processing by the priority-based job controlling mechanism, and provides the users with quality of services (QoS) for interactive processing. The users can access the analysis results of interactive jobs in preference to the analysis results of batch jobs. The Grid portal has also achieved high-performance computation of MEG analysis with batch processing on the Grid environment. The priority-based job controlling mechanism has been realized to freely assign computing resources to the users' requirements. Furthermore the achievement of high-performance computation contributes greatly to the overall progress of brain science. The portal has thus made it possible for the users to flexibly include the large computational power in what they want to analyze.

  16. The surveillance error grid.

    Science.gov (United States)

    Klonoff, David C; Lias, Courtney; Vigersky, Robert; Clarke, William; Parkes, Joan Lee; Sacks, David B; Kirkman, M Sue; Kovatchev, Boris

    2014-07-01

    Currently used error grids for assessing clinical accuracy of blood glucose monitors are based on out-of-date medical practices. Error grids have not been widely embraced by regulatory agencies for clearance of monitors, but this type of tool could be useful for surveillance of the performance of cleared products. Diabetes Technology Society together with representatives from the Food and Drug Administration, the American Diabetes Association, the Endocrine Society, and the Association for the Advancement of Medical Instrumentation, and representatives of academia, industry, and government, have developed a new error grid, called the surveillance error grid (SEG) as a tool to assess the degree of clinical risk from inaccurate blood glucose (BG) monitors. A total of 206 diabetes clinicians were surveyed about the clinical risk of errors of measured BG levels by a monitor. The impact of such errors on 4 patient scenarios was surveyed. Each monitor/reference data pair was scored and color-coded on a graph per its average risk rating. Using modeled data representative of the accuracy of contemporary meters, the relationships between clinical risk and monitor error were calculated for the Clarke error grid (CEG), Parkes error grid (PEG), and SEG. SEG action boundaries were consistent across scenarios, regardless of whether the patient was type 1 or type 2 or using insulin or not. No significant differences were noted between responses of adult/pediatric or 4 types of clinicians. Although small specific differences in risk boundaries between US and non-US clinicians were noted, the panel felt they did not justify separate grids for these 2 types of clinicians. The data points of the SEG were classified in 15 zones according to their assigned level of risk, which allowed for comparisons with the classic CEG and PEG. Modeled glucose monitor data with realistic self-monitoring of blood glucose errors derived from meter testing experiments plotted on the SEG when compared to

  17. Optimal economic and environment operation of micro-grid power systems

    International Nuclear Information System (INIS)

    Elsied, Moataz; Oukaour, Amrane; Gualous, Hamid; Lo Brutto, Ottavio A.

    2016-01-01

    Highlights: • Real-time energy management system for Micro-Grid power systems is introduced. • The management system considered cost objective function and emission constraints. • The optimization problem is solved using Binary Particle Swarm Algorithm. • Advanced real-time interface libraries are used to run the optimization code. - Abstract: In this paper, an advanced real-time energy management system is proposed in order to optimize micro-grid performance in a real-time operation. The proposed strategy of the management system capitalizes on the power of binary particle swarm optimization algorithm to minimize the energy cost and carbon dioxide and pollutant emissions while maximizing the power of the available renewable energy resources. Advanced real-time interface libraries are used to run the optimization code. The simulation results are considered for three different scenarios considering the complexity of the proposed problem. The proposed management system along with its control system is experimentally tested to validate the simulation results obtained from the optimization algorithm. The experimental results highlight the effectiveness of the proposed management system for micro-grids operation.

  18. Robust pattern decoding in shape-coded structured light

    Science.gov (United States)

    Tang, Suming; Zhang, Xu; Song, Zhan; Song, Lifang; Zeng, Hai

    2017-09-01

    Decoding is a challenging and complex problem in a coded structured light system. In this paper, a robust pattern decoding method is proposed for the shape-coded structured light in which the pattern is designed as grid shape with embedded geometrical shapes. In our decoding method, advancements are made at three steps. First, a multi-template feature detection algorithm is introduced to detect the feature point which is the intersection of each two orthogonal grid-lines. Second, pattern element identification is modelled as a supervised classification problem and the deep neural network technique is applied for the accurate classification of pattern elements. Before that, a training dataset is established, which contains a mass of pattern elements with various blurring and distortions. Third, an error correction mechanism based on epipolar constraint, coplanarity constraint and topological constraint is presented to reduce the false matches. In the experiments, several complex objects including human hand are chosen to test the accuracy and robustness of the proposed method. The experimental results show that our decoding method not only has high decoding accuracy, but also owns strong robustness to surface color and complex textures.

  19. The play grid

    DEFF Research Database (Denmark)

    Fogh, Rune; Johansen, Asger

    2013-01-01

    In this paper we propose The Play Grid, a model for systemizing different play types. The approach is psychological by nature and the actual Play Grid is based, therefore, on two pairs of fundamental and widely acknowledged distinguishing characteristics of the ego, namely: extraversion vs. intro...

  20. Buckling behavior analysis of spacer grid by lateral impact load

    International Nuclear Information System (INIS)

    Yoon, Kyung Ho; Kang, Heung Seok; Kim, Hyung Kyu; Song, Kee Nam

    2000-05-01

    The spacer grid is one of the main structural components in the fuel assembly, Which supports the fuel rods, guides cooling water, and protects the system from an external impact load, such as earthquakes. Therefore, the mechanical and structural properties of the spacer grids must be extensively examined while designing it. In this report, free fall type shock tests on the several kinds of the specimens of the spacer grids were also carried out in order to compare the results among the candidate grids. A free fall carriage on the specimen accomplishes the test. In addition to this, a finite element method for predicting the critical impact strength of the spacer grids is described. FE method on the buckling behavior of the spacer grids are performed for a various array of sizes of the grids considering that the spacer grid is an assembled structure with thin-walled plates and imposing proper boundary conditions by nonlinear dynamic impact analysis using ABAQUS/explicit code. The simulated results results also similarly predicted the local buckling phenomena and were found to give good correspondence with the shock test results

  1. Integration of distributed energy resources into low voltage grid: A market-based multiperiod optimization model

    Energy Technology Data Exchange (ETDEWEB)

    Mashhour, Elahe; Moghaddas-Tafreshi, S.M. [Faculty of Electrical Engineering, K.N. Toosi University of Technology, Seyd Khandan, P.O. Box 16315-1355, Shariati, Tehran (Iran)

    2010-04-15

    This paper develops a multiperiod optimization model for an interconnected micro grid with hierarchical control that participates in wholesale energy market to maximize its benefit (i.e. revenues-costs). In addition to the operational constraints of distributed energy resources (DER) including both inter-temporal and non-inter-temporal types, the adequacy and steady-state security constraints of micro grid and its power losses are incorporated in the optimization model. In the presented model, DER are integrated into low voltage grid considering both technical and economical aspects. This integration as a micro grid can participate in wholesale energy market as an entity with dual role including producer and consumer based on the direction of exchanged power. The developed model is evaluated by testing on a micro grid considering different cases and the results are analyzed. (author)

  2. A Damping Grid Strapdown Inertial Navigation System Based on a Kalman Filter for Ships in Polar Regions.

    Science.gov (United States)

    Huang, Weiquan; Fang, Tao; Luo, Li; Zhao, Lin; Che, Fengzhu

    2017-07-03

    The grid strapdown inertial navigation system (SINS) used in polar navigation also includes three kinds of periodic oscillation errors as common SINS are based on a geographic coordinate system. Aiming ships which have the external information to conduct a system reset regularly, suppressing the Schuler periodic oscillation is an effective way to enhance navigation accuracy. The Kalman filter based on the grid SINS error model which applies to the ship is established in this paper. The errors of grid-level attitude angles can be accurately estimated when the external velocity contains constant error, and then correcting the errors of the grid-level attitude angles through feedback correction can effectively dampen the Schuler periodic oscillation. The simulation results show that with the aid of external reference velocity, the proposed external level damping algorithm based on the Kalman filter can suppress the Schuler periodic oscillation effectively. Compared with the traditional external level damping algorithm based on the damping network, the algorithm proposed in this paper can reduce the overshoot errors when the state of grid SINS is switched from the non-damping state to the damping state, and this effectively improves the navigation accuracy of the system.

  3. The LHCb Grid Simulation

    CERN Multimedia

    Baranov, Alexander

    2016-01-01

    The LHCb Grid access if based on the LHCbDirac system. It provides access to data and computational resources to researchers with different geographical locations. The Grid has a hierarchical topology with multiple sites distributed over the world. The sites differ from each other by their number of CPUs, amount of disk storage and connection bandwidth. These parameters are essential for the Grid work. Moreover, job scheduling and data distribution strategy have a great impact on the grid performance. However, it is hard to choose an appropriate algorithm and strategies as they need a lot of time to be tested on the real grid. In this study, we describe the LHCb Grid simulator. The simulator reproduces the LHCb Grid structure with its sites and their number of CPUs, amount of disk storage and bandwidth connection. We demonstrate how well the simulator reproduces the grid work, show its advantages and limitations. We show how well the simulator reproduces job scheduling and network anomalies, consider methods ...

  4. Investigation of Navier-Stokes Code Verification and Design Optimization

    Science.gov (United States)

    Vaidyanathan, Rajkumar

    2004-01-01

    With rapid progress made in employing computational techniques for various complex Navier-Stokes fluid flow problems, design optimization problems traditionally based on empirical formulations and experiments are now being addressed with the aid of computational fluid dynamics (CFD). To be able to carry out an effective CFD-based optimization study, it is essential that the uncertainty and appropriate confidence limits of the CFD solutions be quantified over the chosen design space. The present dissertation investigates the issues related to code verification, surrogate model-based optimization and sensitivity evaluation. For Navier-Stokes (NS) CFD code verification a least square extrapolation (LSE) method is assessed. This method projects numerically computed NS solutions from multiple, coarser base grids onto a freer grid and improves solution accuracy by minimizing the residual of the discretized NS equations over the projected grid. In this dissertation, the finite volume (FV) formulation is focused on. The interplay between the xi concepts and the outcome of LSE, and the effects of solution gradients and singularities, nonlinear physics, and coupling of flow variables on the effectiveness of LSE are investigated. A CFD-based design optimization of a single element liquid rocket injector is conducted with surrogate models developed using response surface methodology (RSM) based on CFD solutions. The computational model consists of the NS equations, finite rate chemistry, and the k-6 turbulence closure. With the aid of these surrogate models, sensitivity and trade-off analyses are carried out for the injector design whose geometry (hydrogen flow angle, hydrogen and oxygen flow areas and oxygen post tip thickness) is optimized to attain desirable goals in performance (combustion length) and life/survivability (the maximum temperatures on the oxidizer post tip and injector face and a combustion chamber wall temperature). A preliminary multi-objective optimization

  5. TrueGrid: Code the table, tabulate the data

    NARCIS (Netherlands)

    F. Hermans (Felienne); T. van der Storm (Tijs)

    2016-01-01

    textabstractSpreadsheet systems are live programming environments. Both the data and the code are right in front you, and if you edit either of them, the effects are immediately visible. Unfortunately, spreadsheets lack mechanisms for abstraction, such as classes, function definitions etc.

  6. Development of thermal hydraulic evaluation code for CANDU reactors

    International Nuclear Information System (INIS)

    Kim, Man Woong; Yu, Seon Oh; Choi, Yong Seog; Shin, Chull; Hwang, Soo Hyun

    2004-02-01

    To enhance the safety of operating CANDU reactors, the establishment of the safety analysis codes system for CANDU reactors is in progress. As for the development of thermal-hydraulic analysis code for CANDU system, the studies for improvement of evaluation model inside RELAP/CANDU code and the development of safety assessment methodology for GSI (Generic Safety Issues) are in progress as a part of establishment of CANDU safety assessment system. To develop the 3-D thermal-hydraulic analysis code for moderator system, the CFD models for analyzing the CANDU-6 moderator circulation are developed. One model uses a structured grid system with the porous media approach for the 380 Calandria tubes in the core region. The other uses a unstructured grid system on the real geometry of 380 Calandria tubes, so that the detailed fluid flow between the Calandria tubes can be observed. As to the development of thermal-hydraulic analysis code for containment, the study on the applicability of CONTAIN 2.0 code to a CANDU containment was conducted and a simulation of the thermal-hydraulic phenomena during the accident was performed. Besides, the model comparison of ESFs (Engineered Safety Features) inside CONTAIN 2.0 code and PRESCON code has also conducted

  7. Smart homes as a base for smart grids; Smart Home als Basis fuer Smart Grid

    Energy Technology Data Exchange (ETDEWEB)

    Segbusch, Klaus von [ABB AG, Mannheim (Germany). Team Business Development Smart Grids; Struwe, Christian [Busch-Jaeger Elektro GmbH, Luedenscheid (Germany)

    2010-09-15

    Integration of renewable energy sources requires more intelligent distribution systems, i.e. so-called smart grids. For this, it is necessary to integrate the end customers in grid operation, giving them financial incentives, information in near real time from the utility, and means for automatic control of their consumption. (orig.)

  8. Novel grid-based optical Braille conversion: from scanning to wording

    Science.gov (United States)

    Yoosefi Babadi, Majid; Jafari, Shahram

    2011-12-01

    Grid-based optical Braille conversion (GOBCO) is explained in this article. The grid-fitting technique involves processing scanned images taken from old hard-copy Braille manuscripts, recognising and converting them into English ASCII text documents inside a computer. The resulted words are verified using the relevant dictionary to provide the final output. The algorithms employed in this article can be easily modified to be implemented on other visual pattern recognition systems and text extraction applications. This technique has several advantages including: simplicity of the algorithm, high speed of execution, ability to help visually impaired persons and blind people to work with fax machines and the like, and the ability to help sighted people with no prior knowledge of Braille to understand hard-copy Braille manuscripts.

  9. Analysis of turbine-grid interaction of grid-connected wind turbine using HHT

    Science.gov (United States)

    Chen, A.; Wu, W.; Miao, J.; Xie, D.

    2018-05-01

    This paper processes the output power of the grid-connected wind turbine with the denoising and extracting method based on Hilbert Huang transform (HHT) to discuss the turbine-grid interaction. At first, the detailed Empirical Mode Decomposition (EMD) and the Hilbert Transform (HT) are introduced. Then, on the premise of decomposing the output power of the grid-connected wind turbine into a series of Intrinsic Mode Functions (IMFs), energy ratio and power volatility are calculated to detect the unessential components. Meanwhile, combined with vibration function of turbine-grid interaction, data fitting of instantaneous amplitude and phase of each IMF is implemented to extract characteristic parameters of different interactions. Finally, utilizing measured data of actual parallel-operated wind turbines in China, this work accurately obtains the characteristic parameters of turbine-grid interaction of grid-connected wind turbine.

  10. Property Grids for the Kansas High Plains Aquifer from Water Well Drillers' Logs

    Science.gov (United States)

    Bohling, G.; Adkins-Heljeson, D.; Wilson, B. B.

    2017-12-01

    Like a number of state and provincial geological agencies, the Kansas Geological Survey hosts a database of water well drillers' logs, containing the records of sediments and lithologies characterized during drilling. At the moment, the KGS database contains records associated with over 90,000 wells statewide. Over 60,000 of these wells are within the High Plains aquifer (HPA) in Kansas, with the corresponding logs containing descriptions of over 500,000 individual depth intervals. We will present grids of hydrogeological properties for the Kansas HPA developed from this extensive, but highly qualitative, data resource. The process of converting the logs into quantitative form consists of first translating the vast number of unique (and often idiosyncratic) sediment descriptions into a fairly comprehensive set of standardized lithology codes and then mapping the standardized lithologies into a smaller number of property categories. A grid is superimposed on the region and the proportion of each property category is computed within each grid cell, with category proportions in empty grid cells computed by interpolation. Grids of properties such as hydraulic conductivity and specific yield are then computed based on the category proportion grids and category-specific property values. A two-dimensional grid is employed for this large-scale, regional application, with category proportions averaged between two surfaces, such as bedrock and the water table at a particular time (to estimate transmissivity at that time) or water tables at two different times (to estimate specific yield over the intervening time period). We have employed a sequence of water tables for different years, based on annual measurements from an extensive network of wells, providing an assessment of temporal variations in the vertically averaged aquifer properties resulting from water level variations (primarily declines) over time.

  11. Control and operation of wind turbine converters during faults in an offshore wind power plant grid with VSC-HVDC connection

    DEFF Research Database (Denmark)

    Chaudhary, Sanjay; Teodorescu, Remus; Rodriguez, Pedro

    2011-01-01

    Voltage source converter (VSC) based high voltage dc (HVDC) transmission is an attractive technique for large offshore wind power plants, especially when long cable transmission is required for connection to the onshore grid. New multi-MW wind turbines are likely to be equipped with full scale...... converters to meet the stringent grid code requirements. In such a scenario, the offshore grid is terminated to the power electronic converters on all the ends. This paper presents a control scheme for the synchronization and control of the grid side converters (GSC) of the wind turbine generators (WTG......). Current limit control enables the GSC to sustain the fault currents during short circuits in the offshore wind collector system grid. However, power transmission is affected, and the fault has to be isolated. It can be resynchronized after the fault has been cleared and the breaker reclosed. Healthy WTG...

  12. Utility-based Reinforcement Learning for Reactive Grids

    OpenAIRE

    Perez , Julien; Germain-Renaud , Cécile; Kégl , Balázs; Loomis , C.

    2008-01-01

    International audience; Large scale production grids are an important case for autonomic computing. They follow a mutualization paradigm: decision-making (human or automatic) is distributed and largely independent, and, at the same time, it must implement the highlevel goals of the grid management. This paper deals with the scheduling problem with two partially conflicting goals: fairshare and Quality of Service (QoS). Fair sharing is a wellknown issue motivated by return on investment for pa...

  13. Grid connection of active stall wind farms using a VSC based DC transmission system

    DEFF Research Database (Denmark)

    Iov, F.; Sørensen, Poul Ejnar; Hansen, A.D.

    2005-01-01

    Currently, there is an increasing trend to connect large MW wind farms to the transmission system. Requirements that focus on the influence of the farms on the grid stability and power quality, and on the control capabilities of wind farms have already been established. The main trends of modern...... wind turbines/farms are clearly the variable speed operation and a grid connection through a power electronic interface, especially using doubly fed induction generators. Using power electronics the control capabilities of these wind turbines/farms are extended and thus the grid requirements...... are fulfilled. However, the traditional squirrel-cage generators based wind turbines/wind farms directly connected to the grid have less control capabilities. These wind turbines/farms cannot regulate their production and contribute to power system stability. A DC transmission system for connection...

  14. H∞ Robust Current Control for DFIG Based Wind Turbine subject to Grid Voltage Distortions

    DEFF Research Database (Denmark)

    Wang, Yun; Wu, Qiuwei; Gong, Wenming

    2016-01-01

    This paper proposes an H∞ robust current controller for doubly fed induction generator (DFIG) based wind turbines (WTs) subject to grid voltage distortions. The controller is to mitigate the impact of the grid voltage distortions on rotor currents with DFIG parameter perturbation. The grid voltage...... distortions considered include asymmetric voltage dips and grid background harmonics. An uncertain DFIG model is developed with uncertain factors originating from distorted stator voltage, and changed generator parameters due to the flux saturation effect, the skin effect, etc. Weighting functions...... are designed to efficiently track the unbalanced current components and the 5th and 7th background harmonics. The robust stability (RS) and robust performance (RP) of the proposed controller are verified by the structured singular value µ. The performance of the H∞ robust current controller was demonstrated...

  15. A comprehensive WSN-based approach to efficiently manage a Smart Grid.

    Science.gov (United States)

    Martinez-Sandoval, Ruben; Garcia-Sanchez, Antonio-Javier; Garcia-Sanchez, Felipe; Garcia-Haro, Joan; Flynn, David

    2014-10-10

    The Smart Grid (SG) is conceived as the evolution of the current electrical grid representing a big leap in terms of efficiency, reliability and flexibility compared to today's electrical network. To achieve this goal, the Wireless Sensor Networks (WSNs) are considered by the scientific/engineering community to be one of the most suitable technologies to apply SG technology to due to their low-cost, collaborative and long-standing nature. However, the SG has posed significant challenges to utility operators-mainly very harsh radio propagation conditions and the lack of appropriate systems to empower WSN devices-making most of the commercial widespread solutions inadequate. In this context, and as a main contribution, we have designed a comprehensive ad-hoc WSN-based solution for the Smart Grid (SENSED-SG) that focuses on specific implementations of the MAC, the network and the application layers to attain maximum performance and to successfully deal with any arising hurdles. Our approach has been exhaustively evaluated by computer simulations and mathematical analysis, as well as validation within real test-beds deployed in controlled environments. In particular, these test-beds cover two of the main scenarios found in a SG; on one hand, an indoor electrical substation environment, implemented in a High Voltage AC/DC laboratory, and, on the other hand, an outdoor case, deployed in the Transmission and Distribution segment of a power grid. The results obtained show that SENSED-SG performs better and is more suitable for the Smart Grid than the popular ZigBee WSN approach.

  16. Press touch code: A finger press based screen size independent authentication scheme for smart devices.

    Science.gov (United States)

    Ranak, M S A Noman; Azad, Saiful; Nor, Nur Nadiah Hanim Binti Mohd; Zamli, Kamal Z

    2017-01-01

    Due to recent advancements and appealing applications, the purchase rate of smart devices is increasing at a higher rate. Parallely, the security related threats and attacks are also increasing at a greater ratio on these devices. As a result, a considerable number of attacks have been noted in the recent past. To resist these attacks, many password-based authentication schemes are proposed. However, most of these schemes are not screen size independent; whereas, smart devices come in different sizes. Specifically, they are not suitable for miniature smart devices due to the small screen size and/or lack of full sized keyboards. In this paper, we propose a new screen size independent password-based authentication scheme, which also offers an affordable defense against shoulder surfing, brute force, and smudge attacks. In the proposed scheme, the Press Touch (PT)-a.k.a., Force Touch in Apple's MacBook, Apple Watch, ZTE's Axon 7 phone; 3D Touch in iPhone 6 and 7; and so on-is transformed into a new type of code, named Press Touch Code (PTC). We design and implement three variants of it, namely mono-PTC, multi-PTC, and multi-PTC with Grid, on the Android Operating System. An in-lab experiment and a comprehensive survey have been conducted on 105 participants to demonstrate the effectiveness of the proposed scheme.

  17. Press touch code: A finger press based screen size independent authentication scheme for smart devices

    Science.gov (United States)

    Ranak, M. S. A. Noman; Nor, Nur Nadiah Hanim Binti Mohd; Zamli, Kamal Z.

    2017-01-01

    Due to recent advancements and appealing applications, the purchase rate of smart devices is increasing at a higher rate. Parallely, the security related threats and attacks are also increasing at a greater ratio on these devices. As a result, a considerable number of attacks have been noted in the recent past. To resist these attacks, many password-based authentication schemes are proposed. However, most of these schemes are not screen size independent; whereas, smart devices come in different sizes. Specifically, they are not suitable for miniature smart devices due to the small screen size and/or lack of full sized keyboards. In this paper, we propose a new screen size independent password-based authentication scheme, which also offers an affordable defense against shoulder surfing, brute force, and smudge attacks. In the proposed scheme, the Press Touch (PT)—a.k.a., Force Touch in Apple’s MacBook, Apple Watch, ZTE’s Axon 7 phone; 3D Touch in iPhone 6 and 7; and so on—is transformed into a new type of code, named Press Touch Code (PTC). We design and implement three variants of it, namely mono-PTC, multi-PTC, and multi-PTC with Grid, on the Android Operating System. An in-lab experiment and a comprehensive survey have been conducted on 105 participants to demonstrate the effectiveness of the proposed scheme. PMID:29084262

  18. Press touch code: A finger press based screen size independent authentication scheme for smart devices.

    Directory of Open Access Journals (Sweden)

    M S A Noman Ranak

    Full Text Available Due to recent advancements and appealing applications, the purchase rate of smart devices is increasing at a higher rate. Parallely, the security related threats and attacks are also increasing at a greater ratio on these devices. As a result, a considerable number of attacks have been noted in the recent past. To resist these attacks, many password-based authentication schemes are proposed. However, most of these schemes are not screen size independent; whereas, smart devices come in different sizes. Specifically, they are not suitable for miniature smart devices due to the small screen size and/or lack of full sized keyboards. In this paper, we propose a new screen size independent password-based authentication scheme, which also offers an affordable defense against shoulder surfing, brute force, and smudge attacks. In the proposed scheme, the Press Touch (PT-a.k.a., Force Touch in Apple's MacBook, Apple Watch, ZTE's Axon 7 phone; 3D Touch in iPhone 6 and 7; and so on-is transformed into a new type of code, named Press Touch Code (PTC. We design and implement three variants of it, namely mono-PTC, multi-PTC, and multi-PTC with Grid, on the Android Operating System. An in-lab experiment and a comprehensive survey have been conducted on 105 participants to demonstrate the effectiveness of the proposed scheme.

  19. A derived heuristics based multi-objective optimization procedure for micro-grid scheduling

    Science.gov (United States)

    Li, Xin; Deb, Kalyanmoy; Fang, Yanjun

    2017-06-01

    With the availability of different types of power generators to be used in an electric micro-grid system, their operation scheduling as the load demand changes with time becomes an important task. Besides satisfying load balance constraints and the generator's rated power, several other practicalities, such as limited availability of grid power and restricted ramping of power output from generators, must all be considered during the operation scheduling process, which makes it difficult to decide whether the optimization results are accurate and satisfactory. In solving such complex practical problems, heuristics-based customized optimization algorithms are suggested. However, due to nonlinear and complex interactions of variables, it is difficult to come up with heuristics in such problems off-hand. In this article, a two-step strategy is proposed in which the first task deciphers important heuristics about the problem and the second task utilizes the derived heuristics to solve the original problem in a computationally fast manner. Specifically, the specific operation scheduling is considered from a two-objective (cost and emission) point of view. The first task develops basic and advanced level knowledge bases offline from a series of prior demand-wise optimization runs and then the second task utilizes them to modify optimized solutions in an application scenario. Results on island and grid connected modes and several pragmatic formulations of the micro-grid operation scheduling problem clearly indicate the merit of the proposed two-step procedure.

  20. Sobol indices for dimension adaptivity in sparse grids

    NARCIS (Netherlands)

    Dwight, R.P.; Desmedt, S.G.L.; Shoeibi Omrani, P.

    2016-01-01

    Propagation of random variables through computer codes of many inputs is primarily limited by computational expense. The use of sparse grids mitigates these costs somewhat; here we show how Sobol indices can be used to perform dimension adaptivity to mitigate them further. The method is compared to

  1. Four Year-Olds Use Norm-Based Coding for Face Identity

    Science.gov (United States)

    Jeffery, Linda; Read, Ainsley; Rhodes, Gillian

    2013-01-01

    Norm-based coding, in which faces are coded as deviations from an average face, is an efficient way of coding visual patterns that share a common structure and must be distinguished by subtle variations that define individuals. Adults and school-aged children use norm-based coding for face identity but it is not yet known if pre-school aged…

  2. Project Scheduling Heuristics-Based Standard PSO for Task-Resource Assignment in Heterogeneous Grid

    Directory of Open Access Journals (Sweden)

    Ruey-Maw Chen

    2011-01-01

    Full Text Available The task scheduling problem has been widely studied for assigning resources to tasks in heterogeneous grid environment. Effective task scheduling is an important issue for the performance of grid computing. Meanwhile, the task scheduling problem is an NP-complete problem. Hence, this investigation introduces a named “standard“ particle swarm optimization (PSO metaheuristic approach to efficiently solve the task scheduling problems in grid. Meanwhile, two promising heuristics based on multimode project scheduling are proposed to help in solving interesting scheduling problems. They are the best performance resource heuristic and the latest finish time heuristic. These two heuristics applied to the PSO scheme are for speeding up the search of the particle and improving the capability of finding a sound schedule. Moreover, both global communication topology and local ring communication topology are also investigated for efficient study of proposed scheme. Simulation results demonstrate that the proposed approach in this investigation can successfully solve the task-resource assignment problems in grid computing and similar scheduling problems.

  3. Commutative discrete filtering on unstructured grids based on least-squares techniques

    International Nuclear Information System (INIS)

    Haselbacher, Andreas; Vasilyev, Oleg V.

    2003-01-01

    The present work is concerned with the development of commutative discrete filters for unstructured grids and contains two main contributions. First, building on the work of Marsden et al. [J. Comp. Phys. 175 (2002) 584], a new commutative discrete filter based on least-squares techniques is constructed. Second, a new analysis of the discrete commutation error is carried out. The analysis indicates that the discrete commutation error is not only dependent on the number of vanishing moments of the filter weights, but also on the order of accuracy of the discrete gradient operator. The results of the analysis are confirmed by grid-refinement studies

  4. Triple-layer smart grid business model

    DEFF Research Database (Denmark)

    Ma, Zheng; Lundgaard, Morten; Jørgensen, Bo Nørregaard

    2016-01-01

    Viewing the smart grid with the theory of business models may open opportunities in understanding and capturing values in new markets. This study tries to discover and map the smart grid ecosystem-based business model framework with two different environments (sub-Saharan Africa and Denmark......), and identifies the parameters for the smart grid solutions to the emerging markets. This study develops a triple-layer business model including the organizational (Niche), environmental (Intermediate), and global (Dominators) factors. The result uncovers an interface of market factors and stakeholders...... in a generic smart grid constellation. The findings contribute the transferability potential of the smart grid solutions between countries, and indicate the potential to export and import smart grid solutions based on the business modeling....

  5. Comprehensive analysis of the dynamic behavior of grid-connected DFIG-based wind turbines under LVRT conditions

    DEFF Research Database (Denmark)

    Alsmadi, Yazan M.; Xu, Longya; Blaabjerg, Frede

    2015-01-01

    ) capability of wind turbines during grid faults is one of the core requirements to ensure stability in the power grid during transients. The doubly-fed induction generators (DFIGs) offer several advantages when utilized in wind turbines, but discussions about their LVRT capabilities are limited. This paper...... presents a comprehensive study of the LVRT of grid-connected DFIG-based wind turbines. It provides a detailed investigation of the transient characteristics and the dynamic behavior of DFIGs during symmetrical and asymmetrical grid voltage sags. A detailed theoretical study supported by computer......Power generation and grid stability have become key issues in the last decade. The high penetration of large capacity wind generation into the electric power grid has led to serious concerns about their influence on the dynamic behavior of power systems. The Low-Voltage Ride-Through (LVRT...

  6. An Extended Design of the "Grid-Enabled SEE++ System" Based on Globus Toolkit 4 and gLite Conference

    CERN Document Server

    Schreiner, W.; Buchberger, M.; Kaltofen, T.

    2006-01-01

    "Grid-Enabled SEE++" based on the SEE++ software system for the biomechanical 3D simulation of the human eye and its muscles. SEE++ simulates the common eye muscle surgery techniques in a graphic interactive way that is familiar to an experienced surgeon. The goal of "Grid-Enabled SEE++" is to adapt and to extend SEE++ in several steps and to develop an efficient grid-based tool for "Evidence Based Medicine", which supports the surgeons in choosing optimal surgery techniques for the treatments of different syndromes of strabismus. In our previous work, we combined the SEE++ software with the Globus (pre-Web Service) middleware and developed a parallel version of the simulation of the "Hess-Lancaster test" (typical medical examination). By this, we demonstrated how a noticeable speedup can be achieved in SEE++ by the exploitation of the computational power of the Grid. Furthermore, we reported the prototype implementation of a medical database component for "Grid-Enabled SEE++". Finally, we designed a so calle...

  7. Nyx: Adaptive mesh, massively-parallel, cosmological simulation code

    Science.gov (United States)

    Almgren, Ann; Beckner, Vince; Friesen, Brian; Lukic, Zarija; Zhang, Weiqun

    2017-12-01

    Nyx code solves equations of compressible hydrodynamics on an adaptive grid hierarchy coupled with an N-body treatment of dark matter. The gas dynamics in Nyx use a finite volume methodology on an adaptive set of 3-D Eulerian grids; dark matter is represented as discrete particles moving under the influence of gravity. Particles are evolved via a particle-mesh method, using Cloud-in-Cell deposition/interpolation scheme. Both baryonic and dark matter contribute to the gravitational field. In addition, Nyx includes physics for accurately modeling the intergalactic medium; in optically thin limits and assuming ionization equilibrium, the code calculates heating and cooling processes of the primordial-composition gas in an ionizing ultraviolet background radiation field.

  8. Global error estimation based on the tolerance proportionality for some adaptive Runge-Kutta codes

    Science.gov (United States)

    Calvo, M.; González-Pinto, S.; Montijano, J. I.

    2008-09-01

    Modern codes for the numerical solution of Initial Value Problems (IVPs) in ODEs are based in adaptive methods that, for a user supplied tolerance [delta], attempt to advance the integration selecting the size of each step so that some measure of the local error is [similar, equals][delta]. Although this policy does not ensure that the global errors are under the prescribed tolerance, after the early studies of Stetter [Considerations concerning a theory for ODE-solvers, in: R. Burlisch, R.D. Grigorieff, J. Schröder (Eds.), Numerical Treatment of Differential Equations, Proceedings of Oberwolfach, 1976, Lecture Notes in Mathematics, vol. 631, Springer, Berlin, 1978, pp. 188-200; Tolerance proportionality in ODE codes, in: R. März (Ed.), Proceedings of the Second Conference on Numerical Treatment of Ordinary Differential Equations, Humbold University, Berlin, 1980, pp. 109-123] and the extensions of Higham [Global error versus tolerance for explicit Runge-Kutta methods, IMA J. Numer. Anal. 11 (1991) 457-480; The tolerance proportionality of adaptive ODE solvers, J. Comput. Appl. Math. 45 (1993) 227-236; The reliability of standard local error control algorithms for initial value ordinary differential equations, in: Proceedings: The Quality of Numerical Software: Assessment and Enhancement, IFIP Series, Springer, Berlin, 1997], it has been proved that in many existing explicit Runge-Kutta codes the global errors behave asymptotically as some rational power of [delta]. This step-size policy, for a given IVP, determines at each grid point tn a new step-size hn+1=h(tn;[delta]) so that h(t;[delta]) is a continuous function of t. In this paper a study of the tolerance proportionality property under a discontinuous step-size policy that does not allow to change the size of the step if the step-size ratio between two consecutive steps is close to unity is carried out. This theory is applied to obtain global error estimations in a few problems that have been solved with

  9. Active Distribution Grid Management based on Robust AC Optimal Power Flow

    DEFF Research Database (Denmark)

    Soares, Tiago; Bessa, Richard J.; Pinson, Pierre

    2017-01-01

    Further integration of distributed renewable energy sources in distribution systems requires a paradigm change in grid management by the distribution system operators (DSO). DSOs are currently moving to an operational planning approach based on activating flexibility from distributed energy resou...

  10. How should grid operators govern smart grid innovation projects? An embedded case study approach

    International Nuclear Information System (INIS)

    Reuver, Mark de; Lei, Telli van der; Lukszo, Zofia

    2016-01-01

    Grid operators increasingly have to collaborate with other actors in order to realize smart grid innovations. For routine maintenance, grid operators typically acquire technologies in one-off transactions, but the innovative nature of smart grid projects may require more collaborate relationships. This paper studies how a transactional versus relational approach to governing smart grid innovation projects affects incentives for other actors to collaborate. We analyse 34 cases of smart grid innovation projects based on extensive archival data as well as interviews. We find that projects relying on relational governance are more likely to provide incentives for collaboration. Especially non-financial incentives such as reputational benefits and shared intellectual property rights are more likely to be found in projects relying on relational governance. Policy makers that wish to stimulate smart grid innovation projects should consider stimulating long-term relationships between grid operators and third parties, because such relationships are more likely to produce incentives for collaboration. - Highlights: • Smart grids require collaboration between grid operators and other actors. • We contrast transactional and relational governance of smart grid projects. • Long-term relations produce more incentives for smart grid collaboration. • Non-financial incentives are more important in long-term relations. • Policy makers should stimulate long-term relations to stimulate smart grids.

  11. Nbody Simulations and Weak Gravitational Lensing using new HPC-Grid resources: the PI2S2 project

    Science.gov (United States)

    Becciani, U.; Antonuccio-Delogu, V.; Costa, A.; Comparato, M.

    2008-08-01

    We present the main project of the new grid infrastructure and the researches, that have been already started in Sicily and will be completed by next year. The PI2S2 project of the COMETA consortium is funded by the Italian Ministry of University and Research and will be completed in 2009. Funds are from the European Union Structural Funds for Objective 1 regions. The project, together with a similar project called Trinacria GRID Virtual Laboratory (Trigrid VL), aims to create in Sicily a computational grid for e-science and e-commerce applications with the main goal of increasing the technological innovation of local enterprises and their competition on the global market. PI2S2 project aims to build and develop an e-Infrastructure in Sicily, based on the grid paradigm, mainly for research activity using the grid environment and High Performance Computer systems. As an example we present the first results of a new grid version of FLY a tree Nbody code developed by INAF Astrophysical Observatory of Catania, already published in the CPC program Library, that will be used in the Weak Gravitational Lensing field.

  12. Grid simulator for power quality assessment of micro-grids

    DEFF Research Database (Denmark)

    Carrasco, Joaquin Eloy Garcia; Vasquez, Juan Carlos; Guerrero, Josep M.

    2013-01-01

    voltages, low-order harmonics and flicker. The aim of this equipment is to test the performance of a given system under such distorted voltages. A prototype of the simulator, consisting of two inverters connected back-to-back to a 380 V three-phase grid and feeding a micro-grid composed of two......-inverter interfaced distributed generators and a critical load was built and tested. A set of experimental results for linear purely resistive loads, non-linear loads and current-controlled inverters is presented to prove the capabilities of the simulator. Finally, a case study is presented by testing a micro-grid.......In this study, a grid simulator based on a back-to-back inverter topology with resonant controllers is presented. The simulator is able to generate three-phase voltages for a range of amplitudes and frequencies with different types of perturbations, such as voltage sags, steady-state unbalanced...

  13. Operation and Control of a Direct-Driven PMSG-Based Wind Turbine System with an Auxiliary Parallel Grid-Side Converter

    Directory of Open Access Journals (Sweden)

    Jiawei Chu

    2013-07-01

    Full Text Available In this paper, based on the similarity, in structure and principle, between a grid-connected converter for a direct-driven permanent magnet synchronous generator (D-PMSG and an active power filter (APF, a new D-PMSG-based wind turbine (WT system configuration that includes not only an auxiliary converter in parallel with the grid-side converter, but also a coordinated control strategy, is proposed to enhance the low voltage ride through (LVRT capability and improve power quality. During normal operation, the main grid-side converter maintains the DC-link voltage constant, whereas the auxiliary grid-side converter functions as an APF with harmonic suppression and reactive power compensation to improve the power quality. During grid faults, a hierarchical coordinated control scheme for the generator-side converter, main grid-side converter and auxiliary grid-side converter, depending on the grid voltage sags, is presented to enhance the LVRT capability of the direct-driven PMSG WT. The feasibility and the effectiveness of the proposed system’s topology and hierarchical coordinated control strategy were verified using MATLAB/Simulink simulations.

  14. Genome-wide identification of coding and non-coding conserved sequence tags in human and mouse genomes

    Directory of Open Access Journals (Sweden)

    Maggi Giorgio P

    2008-06-01

    Full Text Available Abstract Background The accurate detection of genes and the identification of functional regions is still an open issue in the annotation of genomic sequences. This problem affects new genomes but also those of very well studied organisms such as human and mouse where, despite the great efforts, the inventory of genes and regulatory regions is far from complete. Comparative genomics is an effective approach to address this problem. Unfortunately it is limited by the computational requirements needed to perform genome-wide comparisons and by the problem of discriminating between conserved coding and non-coding sequences. This discrimination is often based (thus dependent on the availability of annotated proteins. Results In this paper we present the results of a comprehensive comparison of human and mouse genomes performed with a new high throughput grid-based system which allows the rapid detection of conserved sequences and accurate assessment of their coding potential. By detecting clusters of coding conserved sequences the system is also suitable to accurately identify potential gene loci. Following this analysis we created a collection of human-mouse conserved sequence tags and carefully compared our results to reliable annotations in order to benchmark the reliability of our classifications. Strikingly we were able to detect several potential gene loci supported by EST sequences but not corresponding to as yet annotated genes. Conclusion Here we present a new system which allows comprehensive comparison of genomes to detect conserved coding and non-coding sequences and the identification of potential gene loci. Our system does not require the availability of any annotated sequence thus is suitable for the analysis of new or poorly annotated genomes.

  15. New Generation GridPix: Development and characterisation of pixelated gaseous detectors based on the Timepix3 chip

    CERN Document Server

    AUTHOR|(CDS)2082958; Hessey, Nigel

    Due to the increasing demands of high energy physics experiments there is a need for particle detectors which enable high precision measurements. In this regard, the GridPix detector is a novel detector concept which combines the benefits of a pixel chip with an integrated gas amplification structure. The resulting unit is a detector sensitive to single electrons with a great potential for particle tracking and energy loss measurements. This thesis is focusing on the development of a new generation of GridPix detectors based on the Timepix3 chip, which implements a high resolution Time to Digital Converter (TDC) in each pixel. After an introductory chapter describing the motivation behind GridPix, the manuscript presents the physics of gaseous detectors in chapter 2 along with the gaseous detectors used for particle tracking in chapter 3. Chapters 4 and 5 are focusing on the tracking performance of GridPix detectors. Chapter 4 presents results obtained with a GridPix detector based on a small scale prototy...

  16. QoS Differential Scheduling in Cognitive-Radio-Based Smart Grid Networks: An Adaptive Dynamic Programming Approach.

    Science.gov (United States)

    Yu, Rong; Zhong, Weifeng; Xie, Shengli; Zhang, Yan; Zhang, Yun

    2016-02-01

    As the next-generation power grid, smart grid will be integrated with a variety of novel communication technologies to support the explosive data traffic and the diverse requirements of quality of service (QoS). Cognitive radio (CR), which has the favorable ability to improve the spectrum utilization, provides an efficient and reliable solution for smart grid communications networks. In this paper, we study the QoS differential scheduling problem in the CR-based smart grid communications networks. The scheduler is responsible for managing the spectrum resources and arranging the data transmissions of smart grid users (SGUs). To guarantee the differential QoS, the SGUs are assigned to have different priorities according to their roles and their current situations in the smart grid. Based on the QoS-aware priority policy, the scheduler adjusts the channels allocation to minimize the transmission delay of SGUs. The entire transmission scheduling problem is formulated as a semi-Markov decision process and solved by the methodology of adaptive dynamic programming. A heuristic dynamic programming (HDP) architecture is established for the scheduling problem. By the online network training, the HDP can learn from the activities of primary users and SGUs, and adjust the scheduling decision to achieve the purpose of transmission delay minimization. Simulation results illustrate that the proposed priority policy ensures the low transmission delay of high priority SGUs. In addition, the emergency data transmission delay is also reduced to a significantly low level, guaranteeing the differential QoS in smart grid.

  17. An Optimal Integrated Control Scheme for Permanent Magnet Synchronous Generator-Based Wind Turbines under Asymmetrical Grid Fault Conditions

    Directory of Open Access Journals (Sweden)

    Dan Wang

    2016-04-01

    Full Text Available In recent years, the increasing penetration level of wind energy into power systems has brought new issues and challenges. One of the main concerns is the issue of dynamic response capability during outer disturbance conditions, especially the fault-tolerance capability during asymmetrical faults. In order to improve the fault-tolerance and dynamic response capability under asymmetrical grid fault conditions, an optimal integrated control scheme for the grid-side voltage-source converter (VSC of direct-driven permanent magnet synchronous generator (PMSG-based wind turbine systems is proposed in this paper. The optimal control strategy includes a main controller and an additional controller. In the main controller, a double-loop controller based on differential flatness-based theory is designed for grid-side VSC. Two parts are involved in the design process of the flatness-based controller: the reference trajectories generation of flatness output and the implementation of the controller. In the additional control aspect, an auxiliary second harmonic compensation control loop based on an improved calculation method for grid-side instantaneous transmission power is designed by the quasi proportional resonant (Quasi-PR control principle, which is able to simultaneously restrain the second harmonic components in active power and reactive power injected into the grid without the respective calculation for current control references. Moreover, to reduce the DC-link overvoltage during grid faults, the mathematical model of DC-link voltage is analyzed and a feedforward modified control factor is added to the traditional DC voltage control loop in grid-side VSC. The effectiveness of the optimal control scheme is verified in PSCAD/EMTDC simulation software.

  18. Study on effects of mixing vane grids on coolant temperature distribution by subchannel analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mao, H.; Yang, B.W.; Han, B. [Xi' an Jiaotong Univ., Shaanxi (China). Science and Technology Center for Advanced Nuclear Fuel Research

    2016-07-15

    Mixing vane grids (MVG) have great influence on coolant temperature field in the rod bundle. The MVG could enhance convective heat transfer between the fuel rod wall and the coolant, and promote inter-subchannel mixing at the same time. For the influence of the MVG on convective heat transfer enhancement, many experiments have been done and several correlations have been developed based on the experimental data. However, inter-subchannel mixing promotion caused by the MVG is not well estimated in subchannel analysis because the information of mixing vanes is totally missing in most subchannel codes. This paper analyzes the influence of mixing vanes on coolant temperature distribution using the improved MVG model in subchannel analysis. The coolant temperature distributions with the MVG are analyzed, and the results show that mixing vanes lead to a more uniform temperature distribution. The performances of split vane grids under different power conditions are evaluated. The results are compared with those of spacer grids without mixing vanes and some conclusions are obtained.

  19. Study on effects of mixing vane grids on coolant temperature distribution by subchannel analysis

    International Nuclear Information System (INIS)

    Mao, H.; Yang, B.W.; Han, B.

    2016-01-01

    Mixing vane grids (MVG) have great influence on coolant temperature field in the rod bundle. The MVG could enhance convective heat transfer between the fuel rod wall and the coolant, and promote inter-subchannel mixing at the same time. For the influence of the MVG on convective heat transfer enhancement, many experiments have been done and several correlations have been developed based on the experimental data. However, inter-subchannel mixing promotion caused by the MVG is not well estimated in subchannel analysis because the information of mixing vanes is totally missing in most subchannel codes. This paper analyzes the influence of mixing vanes on coolant temperature distribution using the improved MVG model in subchannel analysis. The coolant temperature distributions with the MVG are analyzed, and the results show that mixing vanes lead to a more uniform temperature distribution. The performances of split vane grids under different power conditions are evaluated. The results are compared with those of spacer grids without mixing vanes and some conclusions are obtained.

  20. Velocity field calculation for non-orthogonal numerical grids

    Energy Technology Data Exchange (ETDEWEB)

    Flach, G. P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-03-01

    Computational grids containing cell faces that do not align with an orthogonal (e.g. Cartesian, cylindrical) coordinate system are routinely encountered in porous-medium numerical simulations. Such grids are referred to in this study as non-orthogonal grids because some cell faces are not orthogonal to a coordinate system plane (e.g. xy, yz or xz plane in Cartesian coordinates). Non-orthogonal grids are routinely encountered at the Savannah River Site in porous-medium flow simulations for Performance Assessments and groundwater flow modeling. Examples include grid lines that conform to the sloping roof of a waste tank or disposal unit in a 2D Performance Assessment simulation, and grid surfaces that conform to undulating stratigraphic surfaces in a 3D groundwater flow model. Particle tracking is routinely performed after a porous-medium numerical flow simulation to better understand the dynamics of the flow field and/or as an approximate indication of the trajectory and timing of advective solute transport. Particle tracks are computed by integrating the velocity field from cell to cell starting from designated seed (starting) positions. An accurate velocity field is required to attain accurate particle tracks. However, many numerical simulation codes report only the volumetric flowrate (e.g. PORFLOW) and/or flux (flowrate divided by area) crossing cell faces. For an orthogonal grid, the normal flux at a cell face is a component of the Darcy velocity vector in the coordinate system, and the pore velocity for particle tracking is attained by dividing by water content. For a non-orthogonal grid, the flux normal to a cell face that lies outside a coordinate plane is not a true component of velocity with respect to the coordinate system. Nonetheless, normal fluxes are often taken as Darcy velocity components, either naively or with accepted approximation. To enable accurate particle tracking or otherwise present an accurate depiction of the velocity field for a non

  1. Securing the smart grid information exchange

    Energy Technology Data Exchange (ETDEWEB)

    Fries, Steffen; Falk, Rainer [Siemens AG, Corporate Technology, Muenchen (Germany)

    2012-07-01

    The smart grid is based on information exchange between various stakeholders using open communication technologies, to control the physical electric grid through the information grid. Protection against cyber attacks is essential to ensure a reliable operation of the smart grid. This challenge is addressed by various regulatory, standardization, and research activities. After giving an overview of the security demand of a smart grid, existing and appearing standardization activities are described. (orig.)

  2. Camouflage Traffic: Minimizing Message Delay for Smart Grid Applications Under Jamming

    Science.gov (United States)

    2015-01-16

    communications for SCADA sys- tems,” Pipeline and Gas J., vol. 238, Feb. 2011, pp. 1–6. [19] T. S. Sidhu and Y. Yin, “Modelling and simulation for perfor...Camouflage Traffic: Minimizing Message Delay for Smart Grid Applications under Jamming Zhuo Lu, Student Member, IEEE, Wenye Wang, Senior Member, IEEE...spread spectrum systems, which provide jamming resilience via multiple frequency and code channels, must be adapted to the smart grid for secure

  3. Developing a Grid-based search and categorization tool

    CERN Document Server

    Haya, Glenn; Vigen, Jens

    2003-01-01

    Grid technology has the potential to improve the accessibility of digital libraries. The participants in Project GRACE (Grid Search And Categorization Engine) are in the process of developing a search engine that will allow users to search through heterogeneous resources stored in geographically distributed digital collections. What differentiates this project from current search tools is that GRACE will be run on the European Data Grid, a large distributed network, and will not have a single centralized index as current web search engines do. In some cases, the distributed approach offers advantages over the centralized approach since it is more scalable, can be used on otherwise inaccessible material, and can provide advanced search options customized for each data source.

  4. The Monte Carlo photoionization and moving-mesh radiation hydrodynamics code CMACIONIZE

    Science.gov (United States)

    Vandenbroucke, B.; Wood, K.

    2018-04-01

    We present the public Monte Carlo photoionization and moving-mesh radiation hydrodynamics code CMACIONIZE, which can be used to simulate the self-consistent evolution of HII regions surrounding young O and B stars, or other sources of ionizing radiation. The code combines a Monte Carlo photoionization algorithm that uses a complex mix of hydrogen, helium and several coolants in order to self-consistently solve for the ionization and temperature balance at any given type, with a standard first order hydrodynamics scheme. The code can be run as a post-processing tool to get the line emission from an existing simulation snapshot, but can also be used to run full radiation hydrodynamical simulations. Both the radiation transfer and the hydrodynamics are implemented in a general way that is independent of the grid structure that is used to discretize the system, allowing it to be run both as a standard fixed grid code, but also as a moving-mesh code.

  5. SoilGrids1km — Global Soil Information Based on Automated Mapping

    Science.gov (United States)

    Hengl, Tomislav; de Jesus, Jorge Mendes; MacMillan, Robert A.; Batjes, Niels H.; Heuvelink, Gerard B. M.; Ribeiro, Eloi; Samuel-Rosa, Alessandro; Kempen, Bas; Leenaars, Johan G. B.; Walsh, Markus G.; Gonzalez, Maria Ruiperez

    2014-01-01

    Background Soils are widely recognized as a non-renewable natural resource and as biophysical carbon sinks. As such, there is a growing requirement for global soil information. Although several global soil information systems already exist, these tend to suffer from inconsistencies and limited spatial detail. Methodology/Principal Findings We present SoilGrids1km — a global 3D soil information system at 1 km resolution — containing spatial predictions for a selection of soil properties (at six standard depths): soil organic carbon (g kg−1), soil pH, sand, silt and clay fractions (%), bulk density (kg m−3), cation-exchange capacity (cmol+/kg), coarse fragments (%), soil organic carbon stock (t ha−1), depth to bedrock (cm), World Reference Base soil groups, and USDA Soil Taxonomy suborders. Our predictions are based on global spatial prediction models which we fitted, per soil variable, using a compilation of major international soil profile databases (ca. 110,000 soil profiles), and a selection of ca. 75 global environmental covariates representing soil forming factors. Results of regression modeling indicate that the most useful covariates for modeling soils at the global scale are climatic and biomass indices (based on MODIS images), lithology, and taxonomic mapping units derived from conventional soil survey (Harmonized World Soil Database). Prediction accuracies assessed using 5–fold cross-validation were between 23–51%. Conclusions/Significance SoilGrids1km provide an initial set of examples of soil spatial data for input into global models at a resolution and consistency not previously available. Some of the main limitations of the current version of SoilGrids1km are: (1) weak relationships between soil properties/classes and explanatory variables due to scale mismatches, (2) difficulty to obtain covariates that capture soil forming factors, (3) low sampling density and spatial clustering of soil profile locations. However, as the SoilGrids

  6. Passivity-Based Stability Assessment of Grid-Connected VSCs - An Overview

    DEFF Research Database (Denmark)

    Harnefors, Lennart; Wang, Xiongfei; Yepes, Alejandro G.

    2016-01-01

    The interconnection stability of a grid-connected voltage-source converter (VSC) can be assessed by the passivity properties of the VSC input admittance. If critical grid resonances fall within regions where the input admittance acts passively, i.e., has nonnegative real part, then their destabil......The interconnection stability of a grid-connected voltage-source converter (VSC) can be assessed by the passivity properties of the VSC input admittance. If critical grid resonances fall within regions where the input admittance acts passively, i.e., has nonnegative real part...

  7. Evaluation of a Positive Youth Development Program Based on the Repertory Grid Test

    Directory of Open Access Journals (Sweden)

    Daniel T. L. Shek

    2012-01-01

    Full Text Available The repertory grid test, based on personal construct psychology, was used to evaluate the effectiveness of Project P.A.T.H.S. (Positive Adolescent Training through Holistic Social Programmes in Hong Kong. One hundred and four program participants (n=104 were randomly invited to complete a repertory grid based on personal construct theory in order to provide both quantitative and qualitative data for measuring self-identity changes after joining the program. Findings generally showed that the participants perceived that they understood themselves better and had stronger resilience after joining the program. Participants also saw themselves as closer to their ideal selves and other positive role figures (but farther away from a loser after joining the program. This study provides additional support for the effectiveness of the Tier 1 Program of Project P.A.T.H.S. in the Chinese context. This study also shows that the repertory grid test is a useful evaluation method to measure self-identity changes in participants in positive youth development programs.

  8. PV-Powered CoMP-Based Green Cellular Networks with a Standby Grid Supply

    Directory of Open Access Journals (Sweden)

    Abu Jahid

    2017-01-01

    Full Text Available This paper proposes a novel framework for PV-powered cellular networks with a standby grid supply and an essential energy management technique for achieving envisaged green networks. The proposal considers an emerging cellular network architecture employing two types of coordinated multipoint (CoMP transmission techniques for serving the subscribers. Under the proposed framework, each base station (BS is powered by an individual PV solar energy module having an independent storage device. BSs are also connected to the conventional grid supply for meeting additional energy demand. We also propose a dynamic inter-BS solar energy sharing policy through a transmission line for further greening the proposed network by minimizing the consumption from the grid supply. An extensive simulation-based study in the downlink of a Long-Term Evolution (LTE cellular system is carried out for evaluating the energy efficiency performance of the proposed framework. System performance is also investigated for identifying the impact of various system parameters including storage factor, storage capacity, solar generation capacity, transmission line loss, and different CoMP techniques.

  9. Research on the Method of Urban Waterlogging Flood Routing Based on Hexagonal Grid

    Directory of Open Access Journals (Sweden)

    LAI Guangling

    2016-12-01

    Full Text Available An evolution of the urban waterlogging flood routing was studied in this paper based on the method of hexagonal grid modeling. Using the method of discrete grid, established an urban geometry model on account of the regular multi-scale discrete grid. With the fusion of 3D topographic survey data and 2D building vector data, formed a regular network model of surface. This model took multi special block into account, such as urban terrain and buildings. On this basis, a method of reverse flow deduction was proposed, which was an inverse computation from the state of flood to the evolution process. That is, based on the water depth of flood, made use of the connectivity with the outfall to calculate the range of water logging, and then implemented the urban waterlogging flood simulation deduction. The test indicated that, this method can implement the evolution of urban waterlogging scenario deduction effectively. And the correlational research could provide scientific basis for urban disaster prevention and emergency decision-making.

  10. Trellises and Trellis-Based Decoding Algorithms for Linear Block Codes

    Science.gov (United States)

    Lin, Shu

    1998-01-01

    A code trellis is a graphical representation of a code, block or convolutional, in which every path represents a codeword (or a code sequence for a convolutional code). This representation makes it possible to implement Maximum Likelihood Decoding (MLD) of a code with reduced decoding complexity. The most well known trellis-based MLD algorithm is the Viterbi algorithm. The trellis representation was first introduced and used for convolutional codes [23]. This representation, together with the Viterbi decoding algorithm, has resulted in a wide range of applications of convolutional codes for error control in digital communications over the last two decades. There are two major reasons for this inactive period of research in this area. First, most coding theorists at that time believed that block codes did not have simple trellis structure like convolutional codes and maximum likelihood decoding of linear block codes using the Viterbi algorithm was practically impossible, except for very short block codes. Second, since almost all of the linear block codes are constructed algebraically or based on finite geometries, it was the belief of many coding theorists that algebraic decoding was the only way to decode these codes. These two reasons seriously hindered the development of efficient soft-decision decoding methods for linear block codes and their applications to error control in digital communications. This led to a general belief that block codes are inferior to convolutional codes and hence, that they were not useful. Chapter 2 gives a brief review of linear block codes. The goal is to provide the essential background material for the development of trellis structure and trellis-based decoding algorithms for linear block codes in the later chapters. Chapters 3 through 6 present the fundamental concepts, finite-state machine model, state space formulation, basic structural properties, state labeling, construction procedures, complexity, minimality, and

  11. Model Penilaian Risiko Kebakaran Perkotaan dengan Sistem Pakar berbasis GIS Grid-Based

    Directory of Open Access Journals (Sweden)

    Sabrillah Taridala

    2017-12-01

    Full Text Available Abstrak Kota Kendari merupakan suatu kawasan perkotaan dengan luas wilayah terkecil dan jumlah penduduk terpadat di Provinsi Sulawesi Tenggara. Bencana kebakaran di Kota Kendari sering terjadi dan telah menimbulkan kerugian yang cukup banyak, hingga menelan korban jiwa. Penelitian ini bertujuan untuk melakukan penilaian terhadap tingkat risiko bencana kebakaran di Kota Kendari dengan menggunakan pendekatan Sistem Pakar (Expert System berbasis Sistem Informasi Geografis (SIG. Hasil penelitian menujukkan bahwa tingkat risiko kebakaran di Kota Kendari terklasifikasi dalam empat kelas, yaitu tingkat risiko kebakaran sangat tinggi sebanyak 206 grid, tingkat risiko kebakaran tinggi sebanyak 6.815 grid, tingkat risiko kebakaran rendah sebanyak 46.175 grid, dan tingkat risiko kebakaran sangat rendah sebanyak 54.640 grid. Tingkat risiko kebakaran sangat tinggi di Kota Kendari merupakan kawasan terbangun yang berpenduduk padat dengan dominasi jenis material bangunan kayu dan campuran, terletak pada daerah dengan morfologi berbukit, dan aksesibilitas hanya dilalui oleh jalan umum yang memiliki lebar jalur lalu lintas <4 meter. Wilayah dengan tingkat risiko sangat rendah merupakan kawasan non-terbangun yang didominasi oleh badan air (sungai dan rawa, hutan dan sebagian kawasan pertanian (kebun. Kawasan tersebut bermorfologi datar, berbukit dan bergunung. Abstract Kendari city is an urban area with the smallest area and the densest population in Southeast Sulawesi Province. Fire disaster in the city of Kendari often occurs and has caused considerable losses, to claim casualties. This study aims to assess the risk degree of fire disaster in Kendari City using Expert System Approach based on Geographic Information System (GIS. The results showed that the degrees of fire risk in Kendari City were classified into four classes, ie very high fire risk degree, 206 grid, high fire risk degree, 6,815 grid, low fire risk degree, 46.175 grid, and very low fire risk, as

  12. Analysis of the Multi Strategy Goal Programming for Micro-Grid Based on Dynamic ant Genetic Algorithm

    Science.gov (United States)

    Qiu, J. P.; Niu, D. X.

    Micro-grid is one of the key technologies of the future energy supplies. Take economic planning. reliability, and environmental protection of micro grid as a basis for the analysis of multi-strategy objective programming problems for micro grid which contains wind power, solar power, and battery and micro gas turbine. Establish the mathematical model of each power generation characteristics and energy dissipation. and change micro grid planning multi-objective function under different operating strategies to a single objective model based on AHP method. Example analysis shows that in combination with dynamic ant mixed genetic algorithm can get the optimal power output of this model.

  13. WebGIS based on semantic grid model and web services

    Science.gov (United States)

    Zhang, WangFei; Yue, CaiRong; Gao, JianGuo

    2009-10-01

    ontology based on Grid technology and Web Services.

  14. Grid-based lattice summation of electrostatic potentials by assembled rank-structured tensor approximation

    Science.gov (United States)

    Khoromskaia, Venera; Khoromskij, Boris N.

    2014-12-01

    Our recent method for low-rank tensor representation of sums of the arbitrarily positioned electrostatic potentials discretized on a 3D Cartesian grid reduces the 3D tensor summation to operations involving only 1D vectors however retaining the linear complexity scaling in the number of potentials. Here, we introduce and study a novel tensor approach for fast and accurate assembled summation of a large number of lattice-allocated potentials represented on 3D N × N × N grid with the computational requirements only weakly dependent on the number of summed potentials. It is based on the assembled low-rank canonical tensor representations of the collected potentials using pointwise sums of shifted canonical vectors representing the single generating function, say the Newton kernel. For a sum of electrostatic potentials over L × L × L lattice embedded in a box the required storage scales linearly in the 1D grid-size, O(N) , while the numerical cost is estimated by O(NL) . For periodic boundary conditions, the storage demand remains proportional to the 1D grid-size of a unit cell, n = N / L, while the numerical cost reduces to O(N) , that outperforms the FFT-based Ewald-type summation algorithms of complexity O(N3 log N) . The complexity in the grid parameter N can be reduced even to the logarithmic scale O(log N) by using data-sparse representation of canonical N-vectors via the quantics tensor approximation. For justification, we prove an upper bound on the quantics ranks for the canonical vectors in the overall lattice sum. The presented approach is beneficial in applications which require further functional calculus with the lattice potential, say, scalar product with a function, integration or differentiation, which can be performed easily in tensor arithmetics on large 3D grids with 1D cost. Numerical tests illustrate the performance of the tensor summation method and confirm the estimated bounds on the tensor ranks.

  15. Wireless Communications in Smart Grid

    Science.gov (United States)

    Bojkovic, Zoran; Bakmaz, Bojan

    Communication networks play a crucial role in smart grid, as the intelligence of this complex system is built based on information exchange across the power grid. Wireless communications and networking are among the most economical ways to build the essential part of the scalable communication infrastructure for smart grid. In particular, wireless networks will be deployed widely in the smart grid for automatic meter reading, remote system and customer site monitoring, as well as equipment fault diagnosing. With an increasing interest from both the academic and industrial communities, this chapter systematically investigates recent advances in wireless communication technology for the smart grid.

  16. Scalability tests of R-GMA based Grid job monitoring system for CMS Monte Carlo data production

    CERN Document Server

    Bonacorsi, D; Field, L; Fisher, S; Grandi, C; Hobson, P R; Kyberd, P; MacEvoy, B; Nebrensky, J J; Tallini, H; Traylen, S

    2004-01-01

    High Energy Physics experiments such as CMS (Compact Muon Solenoid) at the Large Hadron Collider have unprecedented, large-scale data processing computing requirements, with data accumulating at around 1 Gbyte/s. The Grid distributed computing paradigm has been chosen as the solution to provide the requisite computing power. The demanding nature of CMS software and computing requirements, such as the production of large quantities of Monte Carlo simulated data, makes them an ideal test case for the Grid and a major driver for the development of Grid technologies. One important challenge when using the Grid for large-scale data analysis is the ability to monitor the large numbers of jobs that are being executed simultaneously at multiple remote sites. R-GMA is a monitoring and information management service for distributed resources based on the Grid Monitoring Architecture of the Global Grid Forum. In this paper we report on the first measurements of R-GMA as part of a monitoring architecture to be used for b...

  17. Design of a nuclear fuel rod support grid using axiomatic design

    International Nuclear Information System (INIS)

    Song, Kee Nam; Yoon, Kyung Ho; Kang, Byung Soo; Park, Gyung Jin; Choi, Sung Kyoo

    2002-01-01

    Recently, much attention is imposed on the design of the fuel assemblies in the Pressurized Light Water Reactor (PWR). Spacer grid is one of the main structural components in a fuel assembly. It supports fuel rods, guides cooling water, and maintains a coolable geometry from the external impact loads. In this research, a new shape of the spacer grid is designed by the axiomatic approach. The Independence axiom is utilized for the design. For conceptual design, functional requirements (FRs) are defined and corresponding design parameters (DPs) are found to satisfy FRs in sequence. Overall configuration and shapes are determined in this process. Detail design is carried out based on the result of the axiomatic design. For the detail design, the system performances are evaluated by using linear and nonlinear finite element analysis. The dimensions are determined by optimization. Some commercial codes are utilized for the analysis and design

  18. A Theorem on Grid Access Control

    Institute of Scientific and Technical Information of China (English)

    XU ZhiWei(徐志伟); BU GuanYing(卜冠英)

    2003-01-01

    The current grid security research is mainly focused on the authentication of grid systems. A problem to be solved by grid systems is to ensure consistent access control. This problem is complicated because the hosts in a grid computing environment usually span multiple autonomous administrative domains. This paper presents a grid access control model, based on asynchronous automata theory and the classic Bell-LaPadula model. This model is useful to formally study the confidentiality and integrity problems in a grid computing environment. A theorem is proved, which gives the necessary and sufficient conditions to a grid to maintain confidentiality.These conditions are the formalized descriptions of local (node) relations or relationship between grid subjects and node subjects.

  19. The MammoGrid Project Grids Architecture

    CERN Document Server

    McClatchey, Richard; Hauer, Tamas; Estrella, Florida; Saiz, Pablo; Rogulin, Dmitri; Buncic, Predrag; Clatchey, Richard Mc; Buncic, Predrag; Manset, David; Hauer, Tamas; Estrella, Florida; Saiz, Pablo; Rogulin, Dmitri

    2003-01-01

    The aim of the recently EU-funded MammoGrid project is, in the light of emerging Grid technology, to develop a European-wide database of mammograms that will be used to develop a set of important healthcare applications and investigate the potential of this Grid to support effective co-working between healthcare professionals throughout the EU. The MammoGrid consortium intends to use a Grid model to enable distributed computing that spans national borders. This Grid infrastructure will be used for deploying novel algorithms as software directly developed or enhanced within the project. Using the MammoGrid clinicians will be able to harness the use of massive amounts of medical image data to perform epidemiological studies, advanced image processing, radiographic education and ultimately, tele-diagnosis over communities of medical "virtual organisations". This is achieved through the use of Grid-compliant services [1] for managing (versions of) massively distributed files of mammograms, for handling the distri...

  20. Urban micro-grids

    International Nuclear Information System (INIS)

    Faure, Maeva; Salmon, Martin; El Fadili, Safae; Payen, Luc; Kerlero, Guillaume; Banner, Arnaud; Ehinger, Andreas; Illouz, Sebastien; Picot, Roland; Jolivet, Veronique; Michon Savarit, Jeanne; Strang, Karl Axel

    2017-02-01

    ENEA Consulting published the results of a study on urban micro-grids conducted in partnership with the Group ADP, the Group Caisse des Depots, ENEDIS, Omexom, Total and the Tuck Foundation. This study offers a vision of the definition of an urban micro-grid, the value brought by a micro-grid in different contexts based on real case studies, and the upcoming challenges that micro-grid stakeholders will face (regulation, business models, technology). The electric production and distribution system, as the backbone of an increasingly urbanized and energy dependent society, is urged to shift towards a more resilient, efficient and environment-friendly infrastructure. Decentralisation of electricity production into densely populated areas is a promising opportunity to achieve this transition. A micro-grid enhances local production through clustering electricity producers and consumers within a delimited electricity network; it has the ability to disconnect from the main grid for a limited period of time, offering an energy security service to its customers during grid outages for example. However: The islanding capability is an inherent feature of the micro-grid concept that leads to a significant premium on electricity cost, especially in a system highly reliant on intermittent electricity production. In this case, a smart grid, with local energy production and no islanding capability, can be customized to meet relevant sustainability and cost savings goals at lower costs For industrials, urban micro-grids can be economically profitable in presence of high share of reliable energy production and thermal energy demand micro-grids face strong regulatory challenges that should be overcome for further development Whether islanding is or is not implemented into the system, end-user demand for a greener, more local, cheaper and more reliable energy, as well as additional services to the grid, are strong drivers for local production and consumption. In some specific cases

  1. Mesh-based parallel code coupling interface

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, K.; Steckel, B. (eds.) [GMD - Forschungszentrum Informationstechnik GmbH, St. Augustin (DE). Inst. fuer Algorithmen und Wissenschaftliches Rechnen (SCAI)

    2001-04-01

    MpCCI (mesh-based parallel code coupling interface) is an interface for multidisciplinary simulations. It provides industrial end-users as well as commercial code-owners with the facility to combine different simulation tools in one environment. Thereby new solutions for multidisciplinary problems will be created. This opens new application dimensions for existent simulation tools. This Book of Abstracts gives a short overview about ongoing activities in industry and research - all presented at the 2{sup nd} MpCCI User Forum in February 2001 at GMD Sankt Augustin. (orig.) [German] MpCCI (mesh-based parallel code coupling interface) definiert eine Schnittstelle fuer multidisziplinaere Simulationsanwendungen. Sowohl industriellen Anwender als auch kommerziellen Softwarehersteller wird mit MpCCI die Moeglichkeit gegeben, Simulationswerkzeuge unterschiedlicher Disziplinen miteinander zu koppeln. Dadurch entstehen neue Loesungen fuer multidisziplinaere Problemstellungen und fuer etablierte Simulationswerkzeuge ergeben sich neue Anwendungsfelder. Dieses Book of Abstracts bietet einen Ueberblick ueber zur Zeit laufende Arbeiten in der Industrie und in der Forschung, praesentiert auf dem 2{sup nd} MpCCI User Forum im Februar 2001 an der GMD Sankt Augustin. (orig.)

  2. Grid requirements applicable to future NPPs in the new European Electricity Framework

    International Nuclear Information System (INIS)

    Beato Castro, D.; Padill, C. M.

    2000-01-01

    With a view to keeping nuclear energy as an option for future power generation in a competitive market and taking advantage of the current operating experience, a group of European electric utilities have come together to define common requirements for the design and supply of future Light Water Reactor (LWR) plants connected to the electrical system. These requirements, defined with the aim of standardizing and adapting design to the conditions of the new electricity framework, are being included in the European Utility Requirements (EUR) document. Although there are different types of power plants operating appropriately in large electrical systems, the idea is to find the minimum requirements that will allow growth of this type of energy in the European electricity industry without reducing quality, safety and reliability of interconnected electrical systems. It is therefore necessary to take into account the features of the existing power systems and the operating characteristics and design of nuclear power plants so as to harmonize their respective technical peculiarities in the framework of the deregulated electricity sector. The definition of these grid requirements is based primarily on the operating conditions of the Union pour la Coordination de la Production et le Transport de L'Electricite (UCPTE) grid and takes into account the current Grid Code of the main European countries, for the forthcoming Issue C. This paper sets outs the most relevant aspects of the grid requirements, included in Chapter 2.3 of the EUR document Grid Requirements, Issue B, for the connection of future nuclear power plants in the European electricity system, and others that are being considered in the preparation of the new issue of the document that will take into account the deregulated electricity market situation and deal with the following aspects: General characteristics. Operation of a plant under normal grid conditions. Operation of a plant under disturbed grid

  3. Benchmarking of Grid Fault Modes in Single-Phase Grid-Connected Photovoltaic Systems

    DEFF Research Database (Denmark)

    Yang, Yongheng; Blaabjerg, Frede; Zou, Zhixiang

    2013-01-01

    Pushed by the booming installations of singlephase photovoltaic (PV) systems, the grid demands regarding the integration of PV systems are expected to be modified. Hence, the future PV systems should become more active with functionalities of Low Voltage Ride-Through (LVRT) and grid support...... phase systems under grid faults. The intent of this paper is to present a benchmarking of grid fault modes that might come in future single-phase PV systems. In order to map future challenges, the relevant synchronization and control strategies are discussed. Some faulty modes are studied experimentally...... and provided at the end of this paper. It is concluded that there are extensive control possibilities in single-phase PV systems under grid faults. The Second Order General Integral based PLL technique might be the most promising candidate for future single-phase PV systems because of its fast adaptive...

  4. An Enhanced LVRT Scheme for DFIG-based WECSs under Both Balanced and Unbalanced Grid Voltage Sags

    DEFF Research Database (Denmark)

    Mohammadi, Jafar; Afsharnia, Saeed; Ebrahimzadeh, Esmaeil

    2017-01-01

    reactive power into the grid. The passive compensator is based on a three-phase stator damping resistor (SDR) located in series with the stator windings. The proposed scheme decreases the negative effects of grid voltage sags in the DFIG system including the rotor over-currents, electromagnetic torque...

  5. Hardware-efficient bosonic quantum error-correcting codes based on symmetry operators

    Science.gov (United States)

    Niu, Murphy Yuezhen; Chuang, Isaac L.; Shapiro, Jeffrey H.

    2018-03-01

    We establish a symmetry-operator framework for designing quantum error-correcting (QEC) codes based on fundamental properties of the underlying system dynamics. Based on this framework, we propose three hardware-efficient bosonic QEC codes that are suitable for χ(2 )-interaction based quantum computation in multimode Fock bases: the χ(2 ) parity-check code, the χ(2 ) embedded error-correcting code, and the χ(2 ) binomial code. All of these QEC codes detect photon-loss or photon-gain errors by means of photon-number parity measurements, and then correct them via χ(2 ) Hamiltonian evolutions and linear-optics transformations. Our symmetry-operator framework provides a systematic procedure for finding QEC codes that are not stabilizer codes, and it enables convenient extension of a given encoding to higher-dimensional qudit bases. The χ(2 ) binomial code is of special interest because, with m ≤N identified from channel monitoring, it can correct m -photon-loss errors, or m -photon-gain errors, or (m -1 )th -order dephasing errors using logical qudits that are encoded in O (N ) photons. In comparison, other bosonic QEC codes require O (N2) photons to correct the same degree of bosonic errors. Such improved photon efficiency underscores the additional error-correction power that can be provided by channel monitoring. We develop quantum Hamming bounds for photon-loss errors in the code subspaces associated with the χ(2 ) parity-check code and the χ(2 ) embedded error-correcting code, and we prove that these codes saturate their respective bounds. Our χ(2 ) QEC codes exhibit hardware efficiency in that they address the principal error mechanisms and exploit the available physical interactions of the underlying hardware, thus reducing the physical resources required for implementing their encoding, decoding, and error-correction operations, and their universal encoded-basis gate sets.

  6. Characterization of a Power Electronic Grid Simulator for Wind Turbine Generator Compliance Testing

    DEFF Research Database (Denmark)

    Glasdam, Jakob Bærholm; Gevorgian, V.; Wallen, R.

    2014-01-01

    This paper presents the commissioning results and testing capabilities of a multi-megawatt power electronic grid simulator situated in National Renewable Energy Laboratory’s (NREL’s) new testing facility. The commissioning is done using a commercial type 4 multi-megawatt sized wind turbine...... generator (WTG) installed in NREL’s new 5 MW dynamometer and a kilowatt sized type 1 WTG connected to the existing 2.5 MW dynamometer at NREL. The paper demonstrates the outstanding testing capability of the grid simulator and its application in the grid code compliance evaluation of WTGs including balanced...

  7. GriF: A Grid framework for a Web Service approach to reactive scattering

    Science.gov (United States)

    Manuali, C.; Laganà, A.; Rampino, S.

    2010-07-01

    Grid empowered calculations are becoming an important advanced tool indispensable for scientific advances. The possibility of simplifying and harmonizing the work carried out by computational scientists using a Web Service approach is considered here. To this end, a new Collaborative Grid Framework has been developed and tested. As a study case a three dimensional reactive scattering code dealing with atom-diatom systems has been considered. To this end an extended study of the energy dependence of the electronically adiabatic reactivity of N+N has been performed on the EGEE Grid.

  8. Incentive-compatible demand-side management for smart grids based on review strategies

    Science.gov (United States)

    Xu, Jie; van der Schaar, Mihaela

    2015-12-01

    Demand-side load management is able to significantly improve the energy efficiency of smart grids. Since the electricity production cost depends on the aggregate energy usage of multiple consumers, an important incentive problem emerges: self-interested consumers want to increase their own utilities by consuming more than the socially optimal amount of energy during peak hours since the increased cost is shared among the entire set of consumers. To incentivize self-interested consumers to take the socially optimal scheduling actions, we design a new class of protocols based on review strategies. These strategies work as follows: first, a review stage takes place in which a statistical test is performed based on the daily prices of the previous billing cycle to determine whether or not the other consumers schedule their electricity loads in a socially optimal way. If the test fails, the consumers trigger a punishment phase in which, for a certain time, they adjust their energy scheduling in such a way that everybody in the consumer set is punished due to an increased price. Using a carefully designed protocol based on such review strategies, consumers then have incentives to take the socially optimal load scheduling to avoid entering this punishment phase. We rigorously characterize the impact of deploying protocols based on review strategies on the system's as well as the users' performance and determine the optimal design (optimal billing cycle, punishment length, etc.) for various smart grid deployment scenarios. Even though this paper considers a simplified smart grid model, our analysis provides important and useful insights for designing incentive-compatible demand-side management schemes based on aggregate energy usage information in a variety of practical scenarios.

  9. Calculation approaches for grid usage fees to influence the load curve in the distribution grid level

    International Nuclear Information System (INIS)

    Illing, Bjoern

    2014-01-01

    Dominated by the energy policy the decentralized German energy market is changing. One mature target of the government is to increase the contribution of renewable generation to the gross electricity consumption. In order to achieve this target disadvantages like an increased need for capacity management occurs. Load reduction and variable grid fees offer the grid operator solutions to realize capacity management by influencing the load profile. The evolution of the current grid fees towards more causality is required to adapt these approaches. Two calculation approaches are developed in this assignment. On the one hand multivariable grid fees keeping the current components demand and energy charge. Additional to the grid costs grid load dependent parameters like the amount of decentralized feed-ins, time and local circumstances as well as grid capacities are considered. On the other hand the grid fee flat-rate which represents a demand based model on a monthly level. Both approaches are designed to meet the criteria for future grid fees. By means of a case study the effects of the grid fees on the load profile at the low voltage grid is simulated. Thereby the consumption is represented by different behaviour models and the results are scaled at the benchmark grid area. The resulting load curve is analyzed concerning the effects of peak load reduction as well as the integration of renewable energy sources. Additionally the combined effect of grid fees and electricity tariffs is evaluated. Finally the work discusses the launching of grid fees in the tense atmosphere of politics, legislation and grid operation. Results of this work are two calculation approaches designed for grid operators to define the grid fees. Multivariable grid fees are based on the current calculation scheme. Hereby demand and energy charges are weighted by time, locational and load related dependencies. The grid fee flat-rate defines a limitation in demand extraction. Different demand levels

  10. Development of System Based Code: Case Study of Life-Cycle Margin Evaluation

    International Nuclear Information System (INIS)

    Tai Asayama; Masaki Morishita; Masanori Tashimo

    2006-01-01

    For a leap of progress in structural deign of nuclear plant components, The late Professor Emeritus Yasuhide Asada proposed the System Based Code. The key concepts of the System Based Code are; (1) life-cycle margin optimization, (2) expansion of technical options as well as combinations of technical options beyond the current codes and standards, and (3) designing to clearly defined target reliabilities. Those concepts are very new to most of the nuclear power plant designers who are naturally obliged to design to current codes and standards; the application of the concepts of the System Based Code to design will lead to entire change of practices that designers have long been accustomed to. On the other hand, experienced designers are supposed to have expertise that can support and accelerate the development of the System Based Code. Therefore, interfacing with experienced designers is of crucial importance for the development of the System Based Code. The authors conducted a survey on the acceptability of the System Based Code concept. The results were analyzed from the possibility of improving structural design both in terms of reliability and cost effectiveness by the introduction of the System Based Code concept. It was concluded that the System Based Code is beneficial for those purposes. Also described is the expertise elicited from the results of the survey that can be reflected to the development of the System Based Code. (authors)

  11. Cost-effective GPU-grid for genome-wide epistasis calculations.

    Science.gov (United States)

    Pütz, B; Kam-Thong, T; Karbalai, N; Altmann, A; Müller-Myhsok, B

    2013-01-01

    Until recently, genotype studies were limited to the investigation of single SNP effects due to the computational burden incurred when studying pairwise interactions of SNPs. However, some genetic effects as simple as coloring (in plants and animals) cannot be ascribed to a single locus but only understood when epistasis is taken into account [1]. It is expected that such effects are also found in complex diseases where many genes contribute to the clinical outcome of affected individuals. Only recently have such problems become feasible computationally. The inherently parallel structure of the problem makes it a perfect candidate for massive parallelization on either grid or cloud architectures. Since we are also dealing with confidential patient data, we were not able to consider a cloud-based solution but had to find a way to process the data in-house and aimed to build a local GPU-based grid structure. Sequential epistatsis calculations were ported to GPU using CUDA at various levels. Parallelization on the CPU was compared to corresponding GPU counterparts with regards to performance and cost. A cost-effective solution was created by combining custom-built nodes equipped with relatively inexpensive consumer-level graphics cards with highly parallel GPUs in a local grid. The GPU method outperforms current cluster-based systems on a price/performance criterion, as a single GPU shows speed performance comparable up to 200 CPU cores. The outlined approach will work for problems that easily lend themselves to massive parallelization. Code for various tasks has been made available and ongoing development of tools will further ease the transition from sequential to parallel algorithms.

  12. COSINE software development based on code generation technology

    International Nuclear Information System (INIS)

    Ren Hao; Mo Wentao; Liu Shuo; Zhao Guang

    2013-01-01

    The code generation technology can significantly improve the quality and productivity of software development and reduce software development risk. At present, the code generator is usually based on UML model-driven technology, which can not satisfy the development demand of nuclear power calculation software. The feature of scientific computing program was analyzed and the FORTRAN code generator (FCG) based on C# was developed in this paper. FCG can generate module variable definition FORTRAN code automatically according to input metadata. FCG also can generate memory allocation interface for dynamic variables as well as data access interface. FCG was applied to the core and system integrated engine for design and analysis (COSINE) software development. The result shows that FCG can greatly improve the development efficiency of nuclear power calculation software, and reduce the defect rate of software development. (authors)

  13. Damping Methods for Resonances Caused by LCL-Filter-Based Current-Controlled Grid-Tied Power Inverters

    DEFF Research Database (Denmark)

    Wu, Weimin; Liu, Yuan; He, Yuanbin

    2017-01-01

    Grid-tied voltage source inverters using LCL filter have been widely adopted in distributed power generation systems (DPGSs). As high-order LCL filters contain multiple resonant frequencies, switching harmonics generated by the inverter and current harmonics generated by the active/passive loads...... innovative damping methods have been proposed. A comprehensive overview on those contributions and their classification on the inverter- and grid-side damping measures are presented. Based on the concept of the impedance-based stability analysis, all damping methods can ensure the system stability...

  14. Design and implementation of a web-based data grid management system for enterprise PACS backup and disaster recovery

    Science.gov (United States)

    Zhou, Zheng; Ma, Kevin; Talini, Elisa; Documet, Jorge; Lee, Jasper; Liu, Brent

    2007-03-01

    A cross-continental Data Grid infrastructure has been developed at the Image Processing and Informatics (IPI) research laboratory as a fault-tolerant image data backup and disaster recovery solution for Enterprise PACS. The Data Grid stores multiple copies of the imaging studies as well as the metadata, such as patient and study information, in geographically distributed computers and storage devices involving three different continents: America, Asia and Europe. This effectively prevents loss of image data and accelerates data recovery in the case of disaster. However, the lack of centralized management system makes the administration of the current Data Grid difficult. Three major challenges exist in current Data Grid management: 1. No single user interface to access and administrate each geographically separate component; 2. No graphical user interface available, resulting in command-line-based administration; 3. No single sign-on access to the Data Grid; administrators have to log into every Grid component with different corresponding user names/passwords. In this paper we are presenting a prototype of a unique web-based access interface for both Data Grid administrators and users. The interface has been designed to be user-friendly; it provides necessary instruments to constantly monitor the current status of the Data Grid components and their contents from any locations, contributing to longer system up-time.

  15. CFD code verification and the method of manufactured solutions

    International Nuclear Information System (INIS)

    Pelletier, D.; Roache, P.J.

    2002-01-01

    This paper presents the Method of Manufactured Solutions (MMS) for CFD code verification. The MMS provides benchmark solutions for direct evaluation of the solution error. The best benchmarks are exact analytical solutions with sufficiently complex solution structure to ensure that all terms of the differential equations are exercised in the simulation. The MMS provides a straight forward and general procedure for generating such solutions. When used with systematic grid refinement studies, which are remarkably sensitive, the MMS provides strong code verification with a theorem-like quality. The MMS is first presented on simple 1-D examples. Manufactured solutions for more complex problems are then presented with sample results from grid convergence studies. (author)

  16. Resistor-logic demultiplexers for nanoelectronics based on constant-weight codes.

    Science.gov (United States)

    Kuekes, Philip J; Robinett, Warren; Roth, Ron M; Seroussi, Gadiel; Snider, Gregory S; Stanley Williams, R

    2006-02-28

    The voltage margin of a resistor-logic demultiplexer can be improved significantly by basing its connection pattern on a constant-weight code. Each distinct code determines a unique demultiplexer, and therefore a large family of circuits is defined. We consider using these demultiplexers for building nanoscale crossbar memories, and determine the voltage margin of the memory system based on a particular code. We determine a purely code-theoretic criterion for selecting codes that will yield memories with large voltage margins, which is to minimize the ratio of the maximum to the minimum Hamming distance between distinct codewords. For the specific example of a 64 × 64 crossbar, we discuss what codes provide optimal performance for a memory.

  17. Performance Portability Strategies for Grid C++ Expression Templates

    Directory of Open Access Journals (Sweden)

    Boyle Peter A.

    2018-01-01

    Full Text Available One of the key requirements for the Lattice QCD Application Development as part of the US Exascale Computing Project is performance portability across multiple architectures. Using the Grid C++ expression template as a starting point, we report on the progress made with regards to the Grid GPU offloading strategies. We present both the successes and issues encountered in using CUDA, OpenACC and Just-In-Time compilation. Experimentation and performance on GPUs with a SU(3×SU(3 streaming test will be reported. We will also report on the challenges of using current OpenMP 4.x for GPU offloading in the same code.

  18. Performance Portability Strategies for Grid C++ Expression Templates

    Science.gov (United States)

    Boyle, Peter A.; Clark, M. A.; DeTar, Carleton; Lin, Meifeng; Rana, Verinder; Vaquero Avilés-Casco, Alejandro

    2018-03-01

    One of the key requirements for the Lattice QCD Application Development as part of the US Exascale Computing Project is performance portability across multiple architectures. Using the Grid C++ expression template as a starting point, we report on the progress made with regards to the Grid GPU offloading strategies. We present both the successes and issues encountered in using CUDA, OpenACC and Just-In-Time compilation. Experimentation and performance on GPUs with a SU(3)×SU(3) streaming test will be reported. We will also report on the challenges of using current OpenMP 4.x for GPU offloading in the same code.

  19. Numerical investigation on practicability of reducing MCST by using grid spacer in a tight rod bundle

    International Nuclear Information System (INIS)

    Zhu, Xiaojing; Morooka, Shinichi; Oka, Yoshiaki

    2014-01-01

    Highlights: • Standard grid spacer design causes decreased heat transfer in a tight rod bundle. • Heat transfer is greatly enhanced by flow-enhancing features. • Swirling flow adversely affects the heat transfer downstream of grid spacer. • Enhanced heat transfer by existing grid spacer is limited in a short region. • Improved grid spacer can effectively reduce MCST. - Abstract: The numerical investigation was carried out to reveal the practicability of reducing the maximum cladding surface temperature (MCST) within the inner sub-channel of a tight, hexagon rod bundle using commercial CFD code STAR CCM+ 6.04. The special heat transfer and pressure drop characteristics caused by four existing grid spacer designs were discussed in detail by analyzing the effects of grid strap length, different flow enhancing features and different Reynolds numbers. It was found that the local heat transfer within the grid strap is greatly enhanced due to the raised flow velocity. Both the standard grid spacer and the grid spacer with split-vanes cause decreased heat transfer in the downstream region. The friction drag is very influential in the tight rod bundle and can eliminate the positive effect of flow blockage on the heat transfer performance. The grid spacer with flow blockage discs induces relatively good heat transfer performance and higher pressure drop within sub-channels, indicating a tradeoff between the heat transfer augmentation and the pressure drop. The combination of multiple existing grid spacers can reduce the MCST to a certain level, but the corresponding disadvantages cannot be ignored. The improved grid spacer design was proposed based on the overall considerations of heat transfer and pressure drop characteristics and has been proved more suitable to widely reduce MCST for SCWR than any other grid spacer designs involved in present study

  20. An Empirical Model for Vane-Type Vortex Generators in a Navier-Stokes Code

    Science.gov (United States)

    Dudek, Julianne C.

    2005-01-01

    An empirical model which simulates the effects of vane-type vortex generators in ducts was incorporated into the Wind-US Navier-Stokes computational fluid dynamics code. The model enables the effects of the vortex generators to be simulated without defining the details of the geometry within the grid, and makes it practical for researchers to evaluate multiple combinations of vortex generator arrangements. The model determines the strength of each vortex based on the generator geometry and the local flow conditions. Validation results are presented for flow in a straight pipe with a counter-rotating vortex generator arrangement, and the results are compared with experimental data and computational simulations using a gridded vane generator. Results are also presented for vortex generator arrays in two S-duct diffusers, along with accompanying experimental data. The effects of grid resolution and turbulence model are also examined.

  1. Coding Transparency in Object-Based Video

    DEFF Research Database (Denmark)

    Aghito, Shankar Manuel; Forchhammer, Søren

    2006-01-01

    A novel algorithm for coding gray level alpha planes in object-based video is presented. The scheme is based on segmentation in multiple layers. Different coders are specifically designed for each layer. In order to reduce the bit rate, cross-layer redundancies as well as temporal correlation are...

  2. The MICHELLE 2D/3D ES PIC Code Advances and Applications

    CERN Document Server

    Petillo, John; De Ford, John F; Dionne, Norman J; Eppley, Kenneth; Held, Ben; Levush, Baruch; Nelson, Eric M; Panagos, Dimitrios; Zhai, Xiaoling

    2005-01-01

    MICHELLE is a new 2D/3D steady-state and time-domain particle-in-cell (PIC) code* that employs electrostatic and now magnetostatic finite-element field solvers. The code has been used to design and analyze a wide variety of devices that includes multistage depressed collectors, gridded guns, multibeam guns, annular-beam guns, sheet-beam guns, beam-transport sections, and ion thrusters. Latest additions to the MICHELLE/Voyager tool are as follows: 1) a prototype 3D self magnetic field solver using the curl-curl finite-element formulation for the magnetic vector potential, employing edge basis functions and accumulating current with MICHELLE's new unstructured grid particle tracker, 2) the electrostatic field solver now accommodates dielectric media, 3) periodic boundary conditions are now functional on all grids, not just structured grids, 4) the addition of a global optimization module to the user interface where both electrical parameters (such as electrode voltages)can be optimized, and 5) adaptive mesh ref...

  3. Grid collector: An event catalog with automated file management

    International Nuclear Information System (INIS)

    Wu, Kesheng; Zhang, Wei-Ming; Sim, Alexander; Gu, Junmin; Shoshani, Arie

    2003-01-01

    High Energy Nuclear Physics (HENP) experiments such as STAR at BNL and ATLAS at CERN produce large amounts of data that are stored as files on mass storage systems in computer centers. In these files, the basic unit of data is an event. Analysis is typically performed on a selected set of events. The files containing these events have to be located, copied from mass storage systems to disks before analysis, and removed when no longer needed. These file management tasks are tedious and time consuming. Typically, all events contained in the files are read into memory before a selection is made. Since the time to read the events dominate the overall execution time, reading the unwanted event needlessly increases the analysis time. The Grid Collector is a set of software modules that works together to address these two issues. It automates the file management tasks and provides ''direct'' access to the selected events for analyses. It is currently integrated with the STAR analysis framework. The users can select events based on tags, such as, ''production date between March 10 and 20, and the number of charged tracks > 100.'' The Grid Collector locates the files containing relevant events, transfers the files across the Grid if necessary, and delivers the events to the analysis code through the familiar iterators. There has been some research efforts to address the file management issues, the Grid Collector is unique in that it addresses the event access issue together with the file management issues. This makes it more useful to a large variety of users

  4. A Framework for Reverse Engineering Large C++ Code Bases

    NARCIS (Netherlands)

    Telea, Alexandru; Byelas, Heorhiy; Voinea, Lucian

    2009-01-01

    When assessing the quality and maintainability of large C++ code bases, tools are needed for extracting several facts from the source code, such as: architecture, structure, code smells, and quality metrics. Moreover, these facts should be presented in such ways so that one can correlate them and

  5. A Framework for Reverse Engineering Large C++ Code Bases

    NARCIS (Netherlands)

    Telea, Alexandru; Byelas, Heorhiy; Voinea, Lucian

    2008-01-01

    When assessing the quality and maintainability of large C++ code bases, tools are needed for extracting several facts from the source code, such as: architecture, structure, code smells, and quality metrics. Moreover, these facts should be presented in such ways so that one can correlate them and

  6. Design of a nonlinear backstepping control strategy of grid interconnected wind power system based PMSG

    Science.gov (United States)

    Errami, Y.; Obbadi, A.; Sahnoun, S.; Benhmida, M.; Ouassaid, M.; Maaroufi, M.

    2016-07-01

    This paper presents nonlinear backstepping control for Wind Power Generation System (WPGS) based Permanent Magnet Synchronous Generator (PMSG) and connected to utility grid. The block diagram of the WPGS with PMSG and the grid side back-to-back converter is established with the dq frame of axes. This control scheme emphasises the regulation of the dc-link voltage and the control of the power factor at changing wind speed. Besides, in the proposed control strategy of WPGS, Maximum Power Point Tracking (MPPT) technique and pitch control are provided. The stability of the regulators is assured by employing Lyapunov analysis. The proposed control strategy for the system has been validated by MATLAB simulations under varying wind velocity and the grid fault condition. In addition, a comparison of simulation results based on the proposed Backstepping strategy and conventional Vector Control is provided.

  7. Coarse Grid Modeling of Turbine Film Cooling Flows Using Volumetric Source Terms

    Science.gov (United States)

    Heidmann, James D.; Hunter, Scott D.

    2001-01-01

    The recent trend in numerical modeling of turbine film cooling flows has been toward higher fidelity grids and more complex geometries. This trend has been enabled by the rapid increase in computing power available to researchers. However, the turbine design community requires fast turnaround time in its design computations, rendering these comprehensive simulations ineffective in the design cycle. The present study describes a methodology for implementing a volumetric source term distribution in a coarse grid calculation that can model the small-scale and three-dimensional effects present in turbine film cooling flows. This model could be implemented in turbine design codes or in multistage turbomachinery codes such as APNASA, where the computational grid size may be larger than the film hole size. Detailed computations of a single row of 35 deg round holes on a flat plate have been obtained for blowing ratios of 0.5, 0.8, and 1.0, and density ratios of 1.0 and 2.0 using a multiblock grid system to resolve the flows on both sides of the plate as well as inside the hole itself. These detailed flow fields were spatially averaged to generate a field of volumetric source terms for each conservative flow variable. Solutions were also obtained using three coarse grids having streamwise and spanwise grid spacings of 3d, 1d, and d/3. These coarse grid solutions used the integrated hole exit mass, momentum, energy, and turbulence quantities from the detailed solutions as volumetric source terms. It is shown that a uniform source term addition over a distance from the wall on the order of the hole diameter is able to predict adiabatic film effectiveness better than a near-wall source term model, while strictly enforcing correct values of integrated boundary layer quantities.

  8. Image content authentication based on channel coding

    Science.gov (United States)

    Zhang, Fan; Xu, Lei

    2008-03-01

    The content authentication determines whether an image has been tampered or not, and if necessary, locate malicious alterations made on the image. Authentication on a still image or a video are motivated by recipient's interest, and its principle is that a receiver must be able to identify the source of this document reliably. Several techniques and concepts based on data hiding or steganography designed as a means for the image authentication. This paper presents a color image authentication algorithm based on convolution coding. The high bits of color digital image are coded by the convolution codes for the tamper detection and localization. The authentication messages are hidden in the low bits of image in order to keep the invisibility of authentication. All communications channels are subject to errors introduced because of additive Gaussian noise in their environment. Data perturbations cannot be eliminated but their effect can be minimized by the use of Forward Error Correction (FEC) techniques in the transmitted data stream and decoders in the receiving system that detect and correct bits in error. This paper presents a color image authentication algorithm based on convolution coding. The message of each pixel is convolution encoded with the encoder. After the process of parity check and block interleaving, the redundant bits are embedded in the image offset. The tamper can be detected and restored need not accessing the original image.

  9. Impedance Based Analysis and Design of Harmonic Resonant Controller for a Wide Range of Grid Impedance

    DEFF Research Database (Denmark)

    Kwon, Jun Bum; Wang, Xiongfei; Blaabjerg, Frede

    2014-01-01

    This paper investigates the effect of grid impedance variation on harmonic resonant current controllers for gridconnected voltage source converters by means of impedance-based analysis. It reveals that the negative harmonic resistances tend to be derived from harmonic resonant controllers...... in the closed-loop output admittance of converter. Such negative resistances may interact with the grid impedance resulting in steady state error or unstable harmonic compensation. To deal with this problem, a design guideline for harmonic resonant controllers under a wide range of grid impedance is proposed...

  10. Multi-Agent Model-Based Optimization for Future Electrical Grids

    NARCIS (Netherlands)

    Bajracharya, G.

    2014-01-01

    The electricity grid is one of the most complex systems created by human beings. It consists of an intricate network of components such as generators, transmission and distribution lines, transformers, breakers, various controllers, and various measurement and monitoring systems. The grid has been

  11. The Application of Stationary VOC-PR with PLL for Grid side Converter-based Wind Power Generation System

    DEFF Research Database (Denmark)

    Guo, Yougui; Zeng, Ping; Li, Lijuan

    2010-01-01

    Voltage oriented control PR is combined with space vector modulation and phase locked loop to control the grid side converter in wind power generation system in this paper. First the mathematical models of grid side converter and LCL filter as well as grid are given. Then the control strategy...... of grid side converter-based wind power generation system is given in detail. Finally the simulation model consisting of the grid side converter wind power generation system is set up. The simulation results have verified that the control strategy is feasible to be used for control of gird currents......, active power, reactive power and DC-link voltage in wind power generation system. It has laid a good basis for the real system development....

  12. A chimera grid scheme. [multiple overset body-conforming mesh system for finite difference adaptation to complex aircraft configurations

    Science.gov (United States)

    Steger, J. L.; Dougherty, F. C.; Benek, J. A.

    1983-01-01

    A mesh system composed of multiple overset body-conforming grids is described for adapting finite-difference procedures to complex aircraft configurations. In this so-called 'chimera mesh,' a major grid is generated about a main component of the configuration and overset minor grids are used to resolve all other features. Methods for connecting overset multiple grids and modifications of flow-simulation algorithms are discussed. Computational tests in two dimensions indicate that the use of multiple overset grids can simplify the task of grid generation without an adverse effect on flow-field algorithms and computer code complexity.

  13. Implementation of fuzzy-sliding mode based control of a grid connected photovoltaic system.

    Science.gov (United States)

    Menadi, Abdelkrim; Abdeddaim, Sabrina; Ghamri, Ahmed; Betka, Achour

    2015-09-01

    The present work describes an optimal operation of a small scale photovoltaic system connected to a micro-grid, based on both sliding mode and fuzzy logic control. Real time implementation is done through a dSPACE 1104 single board, controlling a boost chopper on the PV array side and a voltage source inverter (VSI) on the grid side. The sliding mode controller tracks permanently the maximum power of the PV array regardless of atmospheric condition variations, while The fuzzy logic controller (FLC) regulates the DC-link voltage, and ensures via current control of the VSI a quasi-total transit of the extracted PV power to the grid under a unity power factor operation. Simulation results, carried out via Matlab-Simulink package were approved through experiment, showing the effectiveness of the proposed control techniques. Copyright © 2015. Published by Elsevier Ltd.

  14. Coupling mechanism of electric vehicle and grid under the background of smart grid

    Science.gov (United States)

    Dong, Mingyu; Li, Dezhi; Chen, Rongjun; Shu, Han; He, Yongxiu

    2018-02-01

    With the development of smart distribution technology in the future, electric vehicle users can not only charge reasonably based on peak-valley price, they can also discharge electricity into the power grid to realize their economic benefit when it’s necessary and thus promote peak load shifting. According to the characteristic that future electric vehicles can discharge, this paper studies the interaction effect between electric vehicles and the grid based on TOU (time of use) Price Strategy. In this paper, four scenarios are used to compare the change of grid load after implementing TOU Price Strategy. The results show that the wide access of electric vehicles can effectively reduce peak and valley difference.

  15. Implementation of a Wind Farm Turbine Control System with Short-Term Grid Faults Management

    DEFF Research Database (Denmark)

    Marra, Francesco; Rasmussen, Tonny Wederberg; Garcia-Valle, Rodrigo

    2010-01-01

    restrictions for the wind turbines behavior especially under grid faults. Wind turbines are requested to stay connected even during faults. These new requirements are challenging the control of the wind turbines and new control strategies are required to meet the target. This paper dealt...... with the implementation of a control strategy in order to stay connected under grid faults. The method aimed to ensure that a wind farm turbine remains connected and no electric power is delivered to the grid during the fault period. The overall system was modelled and simulated by using the software Matlab/Simulink.......The increased penetration of wind power in the grid has led to important technical barriers that limit the development, where the stability of the system plays a key issue. Grid operators in different countries are issuing new grid requirements, the so-called grid codes that impose more...

  16. Risk-Based Two-Stage Stochastic Optimization Problem of Micro-Grid Operation with Renewables and Incentive-Based Demand Response Programs

    Directory of Open Access Journals (Sweden)

    Pouria Sheikhahmadi

    2018-03-01

    Full Text Available The operation problem of a micro-grid (MG in grid-connected mode is an optimization one in which the main objective of the MG operator (MGO is to minimize the operation cost with optimal scheduling of resources and optimal trading energy with the main grid. The MGO can use incentive-based demand response programs (DRPs to pay an incentive to the consumers to change their demands in the peak hours. Moreover, the MGO forecasts the output power of renewable energy resources (RERs and models their uncertainties in its problem. In this paper, the operation problem of an MGO is modeled as a risk-based two-stage stochastic optimization problem. To model the uncertainties of RERs, two-stage stochastic programming is considered and conditional value at risk (CVaR index is used to manage the MGO’s risk-level. Moreover, the non-linear economic models of incentive-based DRPs are used by the MGO to change the peak load. The numerical studies are done to investigate the effect of incentive-based DRPs on the operation problem of the MGO. Moreover, to show the effect of the risk-averse parameter on MGO decisions, a sensitivity analysis is carried out.

  17. HLRmon: a role-based grid accounting report web tool

    International Nuclear Information System (INIS)

    Pra, S D; Fattibene, E; Misurelli, G; Pescarmona, F; Gaido, L

    2008-01-01

    Both Grid users and Grid operators need ways to get CPU usage statistics about jobs executed in a given time period at various different levels, depending on their specific Grid's role and rights. While a Grid user is interested in reports about its own jobs and should not get access to other's data, Site or Virtual Organization (VO) or Regional Operation Centre (ROC) manager would also like to see how resources are used through the Grid in a per Site or per VO basis, or both. The whole set of different reports turns out to be quite large, and various existing tools made to create them tend to better satisfy a single user's category, eventually despite of another. HLRmon results from our efforts to generate suitable reports for all existing categories and has been designed to serve them within a unified layout. Thanks to its ability to authenticate clients through certificate and related authorization rights, it can a-priori restrict the selectable items range offered to the web user, so that sensitive information can only be provided to specifically enabled people. Information are gathered by HLRmon from a Home Location Register (HLR) which stores complete accounting data in a per job basis. Depending on the kind of reports that are to be generated, it directly queries the HLR server using an ad-hoc Distributed Grid Accounting System (DGAS) query tool (tipically user's level detail info), or a local RDBMS table with daily aggregate information in a per Day, Site, VO basis, thus saving connection delay time and needless load on the HLR server

  18. A Pseudo-Temporal Multi-Grid Relaxation Scheme for Solving the Parabolized Navier-Stokes Equations

    Science.gov (United States)

    White, J. A.; Morrison, J. H.

    1999-01-01

    A multi-grid, flux-difference-split, finite-volume code, VULCAN, is presented for solving the elliptic and parabolized form of the equations governing three-dimensional, turbulent, calorically perfect and non-equilibrium chemically reacting flows. The space marching algorithms developed to improve convergence rate and or reduce computational cost are emphasized. The algorithms presented are extensions to the class of implicit pseudo-time iterative, upwind space-marching schemes. A full approximate storage, full multi-grid scheme is also described which is used to accelerate the convergence of a Gauss-Seidel relaxation method. The multi-grid algorithm is shown to significantly improve convergence on high aspect ratio grids.

  19. Intrusion Prevention and Detection in Grid Computing - The ALICE Case

    Science.gov (United States)

    Gomez, Andres; Lara, Camilo; Kebschull, Udo

    2015-12-01

    Grids allow users flexible on-demand usage of computing resources through remote communication networks. A remarkable example of a Grid in High Energy Physics (HEP) research is used in the ALICE experiment at European Organization for Nuclear Research CERN. Physicists can submit jobs used to process the huge amount of particle collision data produced by the Large Hadron Collider (LHC). Grids face complex security challenges. They are interesting targets for attackers seeking for huge computational resources. Since users can execute arbitrary code in the worker nodes on the Grid sites, special care should be put in this environment. Automatic tools to harden and monitor this scenario are required. Currently, there is no integrated solution for such requirement. This paper describes a new security framework to allow execution of job payloads in a sandboxed context. It also allows process behavior monitoring to detect intrusions, even when new attack methods or zero day vulnerabilities are exploited, by a Machine Learning approach. We plan to implement the proposed framework as a software prototype that will be tested as a component of the ALICE Grid middleware.

  20. Intrusion Prevention and Detection in Grid Computing - The ALICE Case

    International Nuclear Information System (INIS)

    Gomez, Andres; Lara, Camilo; Kebschull, Udo

    2015-01-01

    Grids allow users flexible on-demand usage of computing resources through remote communication networks. A remarkable example of a Grid in High Energy Physics (HEP) research is used in the ALICE experiment at European Organization for Nuclear Research CERN. Physicists can submit jobs used to process the huge amount of particle collision data produced by the Large Hadron Collider (LHC). Grids face complex security challenges. They are interesting targets for attackers seeking for huge computational resources. Since users can execute arbitrary code in the worker nodes on the Grid sites, special care should be put in this environment. Automatic tools to harden and monitor this scenario are required. Currently, there is no integrated solution for such requirement. This paper describes a new security framework to allow execution of job payloads in a sandboxed context. It also allows process behavior monitoring to detect intrusions, even when new attack methods or zero day vulnerabilities are exploited, by a Machine Learning approach. We plan to implement the proposed framework as a software prototype that will be tested as a component of the ALICE Grid middleware. (paper)

  1. Long range Debye-Hückel correction for computation of grid-based electrostatic forces between biomacromolecules

    International Nuclear Information System (INIS)

    Mereghetti, Paolo; Martinez, Michael; Wade, Rebecca C

    2014-01-01

    Brownian dynamics (BD) simulations can be used to study very large molecular systems, such as models of the intracellular environment, using atomic-detail structures. Such simulations require strategies to contain the computational costs, especially for the computation of interaction forces and energies. A common approach is to compute interaction forces between macromolecules by precomputing their interaction potentials on three-dimensional discretized grids. For long-range interactions, such as electrostatics, grid-based methods are subject to finite size errors. We describe here the implementation of a Debye-Hückel correction to the grid-based electrostatic potential used in the SDA BD simulation software that was applied to simulate solutions of bovine serum albumin and of hen egg white lysozyme. We found that the inclusion of the long-range electrostatic correction increased the accuracy of both the protein-protein interaction profiles and the protein diffusion coefficients at low ionic strength. An advantage of this method is the low additional computational cost required to treat long-range electrostatic interactions in large biomacromolecular systems. Moreover, the implementation described here for BD simulations of protein solutions can also be applied in implicit solvent molecular dynamics simulations that make use of gridded interaction potentials

  2. Analysis of a grid window structure for RF cavities in a Muon cooling channel

    International Nuclear Information System (INIS)

    Ladran, A.; Li, D.; Moretti, A.; Rimmer, R.; Staples, J.; Virostek, S.; Zisman, M.

    2003-01-01

    We report on the electromagnetic and thermal analysis of a grid window structure for high gradient, low frequency RF cavities. Windows may be utilized to close the beam iris and increase shunt impedance of closed-cell RF cavities. This work complements previous work presented for windows made of solid beryllium foil. An electromagnetic and thermal analysis of the thin wall tubes in a grid pattern was conducted using both MAFIA4 and ANSYS finite element analyses. The results from both codes agreed well for a variety of grid configurations and spacing. The grid configuration where the crossing tubes touched was found to have acceptable E-Fields and H-Fields performance. The thermal profiles for the grid will also be shown to determine a viable cooling profile

  3. Measuring Modularity in Open Source Code Bases

    Directory of Open Access Journals (Sweden)

    Roberto Milev

    2009-03-01

    Full Text Available Modularity of an open source software code base has been associated with growth of the software development community, the incentives for voluntary code contribution, and a reduction in the number of users who take code without contributing back to the community. As a theoretical construct, modularity links OSS to other domains of research, including organization theory, the economics of industry structure, and new product development. However, measuring the modularity of an OSS design has proven difficult, especially for large and complex systems. In this article, we describe some preliminary results of recent research at Carleton University that examines the evolving modularity of large-scale software systems. We describe a measurement method and a new modularity metric for comparing code bases of different size, introduce an open source toolkit that implements this method and metric, and provide an analysis of the evolution of the Apache Tomcat application server as an illustrative example of the insights gained from this approach. Although these results are preliminary, they open the door to further cross-discipline research that quantitatively links the concerns of business managers, entrepreneurs, policy-makers, and open source software developers.

  4. Nodal kinetics model upgrade in the Penn State coupled TRAC/NEM codes

    International Nuclear Information System (INIS)

    Beam, Tara M.; Ivanov, Kostadin N.; Baratta, Anthony J.; Finnemann, Herbert

    1999-01-01

    The Pennsylvania State University currently maintains and does development and verification work for its own versions of the coupled three-dimensional kinetics/thermal-hydraulics codes TRAC-PF1/NEM and TRAC-BF1/NEM. The subject of this paper is nodal model enhancements in the above mentioned codes. Because of the numerous validation studies that have been performed on almost every aspect of these codes, this upgrade is done without a major code rewrite. The upgrade consists of four steps. The first two steps are designed to improve the accuracy of the kinetics model, based on the nodal expansion method. The polynomial expansion solution of 1D transverse integrated diffusion equation is replaced with a solution, which uses a semi-analytic expansion. Further the standard parabolic polynomial representation of the transverse leakage in the above 1D equations is replaced with an improved approximation. The last two steps of the upgrade address the code efficiency by improving the solution of the time-dependent NEM equations and implementing a multi-grid solver. These four improvements are implemented into the standalone NEM kinetics code. Verification of this code was accomplished based on the original verification studies. The results show that the new methods improve the accuracy and efficiency of the code. The verification of the upgraded NEM model in the TRAC-PF1/NEM and TRAC-BF1/NEM coupled codes is underway

  5. Global Population Density Grid Time Series Estimates

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Population Density Grid Time Series Estimates provide a back-cast time series of population density grids based on the year 2000 population grid from SEDAC's...

  6. Active current control in wind power plants during grid faults

    DEFF Research Database (Denmark)

    Martinez, Jorge; Kjær, Phillip C.; Rodriguez, Pedro

    2010-01-01

    Modern wind power plants are required and designed to ride through faults in electrical networks, subject to fault clearing. Wind turbine fault current contribution is required from most countries with a high amount of wind power penetration. In order to comply with such grid code requirements......, wind turbines usually have solutions that enable the turbines to control the generation of reactive power during faults. This paper addresses the importance of using an optimal injection of active current during faults in order to fulfil these grid codes. This is of relevant importance for severe...... faults, causing low voltages at the point of common coupling. As a consequence, a new wind turbine current controller for operation during faults is proposed. It is shown that to achieve the maximum transfer of reactive current at the point of common coupling, a strategy for optimal setting of the active...

  7. Medical image registration algorithms assesment Bronze Standard application enactment on grids using the MOTEUR workflow engine

    CERN Document Server

    Glatard, T; Pennec, X

    2006-01-01

    Medical image registration is pre-processing needed for many medical image analysis procedures. A very large number of registration algorithms are available today, but their performance is often not known and very difficult to assess due to the lack of gold standard. The Bronze Standard algorithm is a very data and compute intensive statistical approach for quantifying registration algorithms accuracy. In this paper, we describe the Bronze Standard application and we discuss the need for grids to tackle such computations on medical image databases. We demonstrate MOTEUR, a service-based workflow engine optimized for dealing with data intensive applications. MOTEUR eases the enactment of the Bronze Standard and similar applications on the EGEE production grid infrastructure. It is a generic workflow engine, based on current standards and freely available, that can be used to instrument legacy application code at low cost.

  8. Implementation and testing of the CFDS-FLOW3D code

    International Nuclear Information System (INIS)

    Smith, B.L.

    1994-03-01

    FLOW3D is a multi-purpose, transient fluid dynamics and heat transfer code developed by Computational Fluid Dynamics Services (CFDS), a branch of AEA Technology, based at Harwell. The code is supplied with a SUN-based operating environment consisting of an interactive grid generator SOPHIA and a post-processor JASPER for graphical display of results. Both SOPHIA and JASPER are extensions of the support software originally written for the ASTEC code, also promoted by CFDS. The latest release of FLOW3D contains well-tested turbulence and combustion models and, in a less-developed form, a multi-phase modelling potential. This document describes briefly the modelling capabilities of FLOW3D (Release 3.2) and outlines implementation procedures for the VAX, CRAY and CONVEX computer systems. Additional remarks are made concerning the in-house support programs which have been specially written in order to adapt existing ASTEC input data for use with FLOW3D; these programs operate within a VAX-VMS environment. Three sample calculations have been performed and results compared with those obtained previously using the ASTEC code, and checked against other available data, where appropriate. (author) 35 figs., 3 tabs., 42 refs

  9. Modeling and Control of VSC based DC Connection for Active Stall Wind Farms to Grid

    DEFF Research Database (Denmark)

    Iov, Florin; Sorensen, Poul; Hansen, Anca-Daniela

    2005-01-01

    Currently, there is an increasing trend to connect large MW wind farms to the transmission system. Therefore the power system becomes more vulnerable and dependent on the wind energy production. At the same time requirements that focus on the influence of the farms on the grid stability and power...... quality, and on the control capabilities of wind farms have already been established. The main trends of modem wind turbines/farms are clearly the variable speed operation and a grid connection through a power electronic interface, especially using doubly-fed induction generators. Using power electronics...... the control capabilities of these wind turbines/farms are extended and thus the grid requirements are fulfilled. However, the traditional squirrel-cage generators based wind turbines/wind farms directly connected to the grid does not have such control capabilities. They produce maximum possible power...

  10. Modelling and Control of VSC based DC Connection for Active Stall Wind Farms to Grid

    DEFF Research Database (Denmark)

    Iov, Florin; Sørensen, Poul; Hansen, Anca Daniela

    2006-01-01

    Currently, there is an increasing trend to connect large MW wind farms to the transmission system. Therefore the power system becomes more vulnerable and dependent on the wind energy production. At the same time requirements that focus on the influence of the farms on the grid stability and power...... quality, and on the control capabilities of wind farms have already been established. The main trends of modern wind turbines/farms are clearly the variable speed operation and a grid connection through a power electronic interface, especially using doubly-fed induction generators. Using power electronics...... the control capabilities of these wind turbines/farms are extended and thus the grid requirements are fulfilled.  However, the traditional squirrel-cage generators based wind turbines/wind farms directly connected to the grid does not have such control capabilities. They produce maximum possible power...

  11. Low-voltage ride-through of a droop-based three-phase four-wire grid-connected microgrid

    DEFF Research Database (Denmark)

    Sadeghkhani, Iman; Golshan, Mohamad Esmail Hamedani; Mehrizi-Sani, Ali

    2018-01-01

    system operations during abnormal grid conditions. The objective of this paper is to propose an LVRT scheme that improves the power quality of the entire microgrid. The developed method is implemented as the controller of the interface voltage-sourced converter (VSC) of a distributed energy resource...... control of each phase and does not require calculation of symmetrical components. Moreover, it can be employed in the VSC control systems with various reference frames and is effective for droop-based grid-connected microgrids with both single-phase and three-phase four-wire configurations. The proposed......The ability of riding through the grid disturbances can increase the integration of microgrids into the distribution system. Consequently, a grid-connected microgrid should provide ancillary services such as low voltage ride-through (LVRT) capability and reactive power support to sustain the power...

  12. Implementation of grid-connected to/from off-grid transference for micro-grid inverters

    OpenAIRE

    Heredero Peris, Daniel; Chillón Antón, Cristian; Pages Gimenez, Marc; Gross, Gabriel Igor; Montesinos Miracle, Daniel

    2013-01-01

    This paper presents the transfer of a microgrid converter from/to on-grid to/from off-grid when the converter is working in two different modes. In the first transfer presented method, the converter operates as a Current Source Inverter (CSI) when on-grid and as a Voltage Source Inverter (VSI) when off-grid. In the second transfer method, the converter is operated as a VSI both, when operated on-grid and off-grid. The two methods are implemented successfully in a real pla...

  13. A sparse grid based method for generative dimensionality reduction of high-dimensional data

    Science.gov (United States)

    Bohn, Bastian; Garcke, Jochen; Griebel, Michael

    2016-03-01

    Generative dimensionality reduction methods play an important role in machine learning applications because they construct an explicit mapping from a low-dimensional space to the high-dimensional data space. We discuss a general framework to describe generative dimensionality reduction methods, where the main focus lies on a regularized principal manifold learning variant. Since most generative dimensionality reduction algorithms exploit the representer theorem for reproducing kernel Hilbert spaces, their computational costs grow at least quadratically in the number n of data. Instead, we introduce a grid-based discretization approach which automatically scales just linearly in n. To circumvent the curse of dimensionality of full tensor product grids, we use the concept of sparse grids. Furthermore, in real-world applications, some embedding directions are usually more important than others and it is reasonable to refine the underlying discretization space only in these directions. To this end, we employ a dimension-adaptive algorithm which is based on the ANOVA (analysis of variance) decomposition of a function. In particular, the reconstruction error is used to measure the quality of an embedding. As an application, the study of large simulation data from an engineering application in the automotive industry (car crash simulation) is performed.

  14. Flexible DWDM Grid Manipulation Using Four Wave Mixing-based Time Lenses

    DEFF Research Database (Denmark)

    Røge, Kasper Meldgaard; Guan, Pengyu; Mulvad, Hans Christian Hansen

    2014-01-01

    An experimental demonstration of dense wavelength-division multiplexing (DWDM) grid manipulation is carried out using two time lenses. A DWDM spectrum is compressed from a 100-GHz to a 28-GHz grid with error-free performance.......An experimental demonstration of dense wavelength-division multiplexing (DWDM) grid manipulation is carried out using two time lenses. A DWDM spectrum is compressed from a 100-GHz to a 28-GHz grid with error-free performance....

  15. Control of Doubly-Fed Induction Generator to Ride-Through Recurring Grid Faults

    DEFF Research Database (Denmark)

    Chen, Wenjie; Xu, Dehong; Zhu, Nan

    2016-01-01

    The wind turbine system (WTS) is required to ride-through recurring grid faults by the new grid codes. Under single grid faults, the fault ride-through (FRT) strategy with rotor-side crowbar is normally used for the doubly-fed induction generator (DFIG) WTS. However, under recurring faults, larger...... transient current and voltage may be produced, and the DFIG may fail to ride-through the second fault even with the rotor-side crowbar. The crowbar can be active again during the voltage recovery, but large electromagnetic torque (EM-torque) fluctuations will be introduced. The reliability of the mechanical...... system will be influenced. In this paper, an FRT strategy for the DFIG WTS to ride-through recurring symmetrical grid faults is investigated. An improved control strategy is introduced and it is applied during the voltage recovery of the grid faults. The decay of the stator natural flux can...

  16. Integrating renewables in distribution grids. Storage, regulation and the interaction of different stakeholders in future grids

    Energy Technology Data Exchange (ETDEWEB)

    Nykamp, S.

    2013-10-18

    In recent years, the transition of the power supply chain towards a sustainable system based on 'green' electricity generation out of renewable energy sources (RES-E) has become a main challenge for grid operators and further stakeholders in the power system. To enable the evaluation of new concepts for the integration of RES-E, first the feed-in characteristics of photovoltaic, wind and biomass generators located in a distribution grid area and based on numerous measured feed-in data are studied in this thesis. The achieved insights from the feed-in profiles can be used for the dimensioning of grid assets. Furthermore, the results are useful for the evaluation of congestion management or for the dimensioning of storage assets in distribution grids. The latter aspect is analyzed in detail such that suitable storage characteristics for an introduction in the grid are determined. An economic approach is presented to derive break-even points for storage assets as a substitute to conventional reinforcements. For a case study from a real world low voltage grid with reinforcement needs, these break-even points are determined and the main influencing parameters are evaluated. A further important question in this context concerns the role DSOs (distribution system operators) may play with the operation of decentralized storage assets since several stakeholders may be interested in using the flexibility provided by these assets. This unclear responsibility also applies to the steering of adjustable consumption devices such as electric heat pumps or electric cars. For decentralized storage assets as well as heat pump appliances, optimal operation modes based on the optimization objectives for a DSO and a trader are derived. It is shown based on real world data that choosing a 'copperplate' scenario is not only technically insufficient for a global balance of the consumption and generation. It may even be harmful for the society from a welfare economic

  17. Differential Evolution Based IDWNN Controller for Fault Ride-Through of Grid-Connected Doubly Fed Induction Wind Generators.

    Science.gov (United States)

    Manonmani, N; Subbiah, V; Sivakumar, L

    2015-01-01

    The key objective of wind turbine development is to ensure that output power is continuously increased. It is authenticated that wind turbines (WTs) supply the necessary reactive power to the grid at the time of fault and after fault to aid the flowing grid voltage. At this juncture, this paper introduces a novel heuristic based controller module employing differential evolution and neural network architecture to improve the low-voltage ride-through rate of grid-connected wind turbines, which are connected along with doubly fed induction generators (DFIGs). The traditional crowbar-based systems were basically applied to secure the rotor-side converter during the occurrence of grid faults. This traditional controller is found not to satisfy the desired requirement, since DFIG during the connection of crowbar acts like a squirrel cage module and absorbs the reactive power from the grid. This limitation is taken care of in this paper by introducing heuristic controllers that remove the usage of crowbar and ensure that wind turbines supply necessary reactive power to the grid during faults. The controller is designed in this paper to enhance the DFIG converter during the grid fault and this controller takes care of the ride-through fault without employing any other hardware modules. The paper introduces a double wavelet neural network controller which is appropriately tuned employing differential evolution. To validate the proposed controller module, a case study of wind farm with 1.5 MW wind turbines connected to a 25 kV distribution system exporting power to a 120 kV grid through a 30 km 25 kV feeder is carried out by simulation.

  18. Differential Evolution Based IDWNN Controller for Fault Ride-Through of Grid-Connected Doubly Fed Induction Wind Generators

    Directory of Open Access Journals (Sweden)

    N. Manonmani

    2015-01-01

    Full Text Available The key objective of wind turbine development is to ensure that output power is continuously increased. It is authenticated that wind turbines (WTs supply the necessary reactive power to the grid at the time of fault and after fault to aid the flowing grid voltage. At this juncture, this paper introduces a novel heuristic based controller module employing differential evolution and neural network architecture to improve the low-voltage ride-through rate of grid-connected wind turbines, which are connected along with doubly fed induction generators (DFIGs. The traditional crowbar-based systems were basically applied to secure the rotor-side converter during the occurrence of grid faults. This traditional controller is found not to satisfy the desired requirement, since DFIG during the connection of crowbar acts like a squirrel cage module and absorbs the reactive power from the grid. This limitation is taken care of in this paper by introducing heuristic controllers that remove the usage of crowbar and ensure that wind turbines supply necessary reactive power to the grid during faults. The controller is designed in this paper to enhance the DFIG converter during the grid fault and this controller takes care of the ride-through fault without employing any other hardware modules. The paper introduces a double wavelet neural network controller which is appropriately tuned employing differential evolution. To validate the proposed controller module, a case study of wind farm with 1.5 MW wind turbines connected to a 25 kV distribution system exporting power to a 120 kV grid through a 30 km 25 kV feeder is carried out by simulation.

  19. Design and Tuning of a Modified Power-Based PLL for Single-Phase Grid-Connected Power Conditioning Systems

    DEFF Research Database (Denmark)

    Golestan, Saeed; Monfared, Mohammad; D. Freijedo, Francisco

    2012-01-01

    One of the most important aspects for the proper operation of the single-phase grid-tied power-conditioning systems is the synchronization with the utility grid. Among various synchronization techniques, phase locked loop (PLL) based algorithms have found a lot of interest for the advantages...

  20. GPU based contouring method on grid DEM data

    Science.gov (United States)

    Tan, Liheng; Wan, Gang; Li, Feng; Chen, Xiaohui; Du, Wenlong

    2017-08-01

    This paper presents a novel method to generate contour lines from grid DEM data based on the programmable GPU pipeline. The previous contouring approaches often use CPU to construct a finite element mesh from the raw DEM data, and then extract contour segments from the elements. They also need a tracing or sorting strategy to generate the final continuous contours. These approaches can be heavily CPU-costing and time-consuming. Meanwhile the generated contours would be unsmooth if the raw data is sparsely distributed. Unlike the CPU approaches, we employ the GPU's vertex shader to generate a triangular mesh with arbitrary user-defined density, in which the height of each vertex is calculated through a third-order Cardinal spline function. Then in the same frame, segments are extracted from the triangles by the geometry shader, and translated to the CPU-side with an internal order in the GPU's transform feedback stage. Finally we propose a "Grid Sorting" algorithm to achieve the continuous contour lines by travelling the segments only once. Our method makes use of multiple stages of GPU pipeline for computation, which can generate smooth contour lines, and is significantly faster than the previous CPU approaches. The algorithm can be easily implemented with OpenGL 3.3 API or higher on consumer-level PCs.

  1. Verification of gyrokinetic microstability codes with an LHD configuration

    Energy Technology Data Exchange (ETDEWEB)

    Mikkelsen, D. R. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Nunami, M. [National Inst. for Fusion Science (Japan); Watanabe, T. -H. [Nagoya Univ. (Japan); Sugama, H. [National Inst. for Fusion Science (Japan); Tanaka, K. [National Inst. for Fusion Science (Japan)

    2014-11-01

    We extend previous benchmarks of the GS2 and GKV-X codes to verify their algorithms for solving the gyrokinetic Vlasov-Poisson equations for plasma microturbulence. Code benchmarks are the most complete way of verifying the correctness of implementations for the solution of mathematical models for complex physical processes such as those studied here. The linear stability calculations reported here are based on the plasma conditions of an ion-ITB plasma in the LHD configuration. The plasma parameters and the magnetic geometry differ from previous benchmarks involving these codes. We find excellent agreement between the independently written pre-processors that calculate the geometrical coefficients used in the gyrokinetic equations. Grid convergence tests are used to establish the resolution and domain size needed to obtain converged linear stability results. The agreement of the frequencies, growth rates and eigenfunctions in the benchmarks reported here provides additional verification that the algorithms used by the GS2 and GKV-X codes are correctly finding the linear eigenvalues and eigenfunctions of the gyrokinetic Vlasov-Poisson equations.

  2. Fast Grid Frequency Support from Distributed Inverter-Based Resources

    Energy Technology Data Exchange (ETDEWEB)

    Hoke, Anderson F [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2018-05-04

    This presentation summarizes power hardware-in-the-loop testing performed to evaluate the ability of distributed inverter-coupled generation to support grid frequency on the fastest time scales. The research found that distributed PV inverters and other DERs can effectively support the grid on sub-second time scales.

  3. A policy-based hierarchical approach for management of grids and networks

    NARCIS (Netherlands)

    Fioreze, Tiago; Neisse, R.; Granville, L.; Almeida, M.J.; Pras, Aiko

    2006-01-01

    Grids are distributed infrastructures that have been used as an important and powerful resource for distributed computing. Since the nodes of a grid can potentially be located in different administrative domains, the underlying network infrastructure that supports grid communications has to be

  4. Mapping PetaSHA Applications to TeraGrid Architectures

    Science.gov (United States)

    Cui, Y.; Moore, R.; Olsen, K.; Zhu, J.; Dalguer, L. A.; Day, S.; Cruz-Atienza, V.; Maechling, P.; Jordan, T.

    2007-12-01

    The Southern California Earthquake Center (SCEC) has a science program in developing an integrated cyberfacility - PetaSHA - for executing physics-based seismic hazard analysis (SHA) computations. The NSF has awarded PetaSHA 15 million allocation service units this year on the fastest supercomputers available within the NSF TeraGrid. However, one size does not fit all, a range of systems are needed to support this effort at different stages of the simulations. Enabling PetaSHA simulations on those TeraGrid architectures to solve both dynamic rupture and seismic wave propagation have been a challenge from both hardware and software levels. This is an adaptation procedure to meet specific requirements of each architecture. It is important to determine how fundamental system attributes affect application performance. We present an adaptive approach in our PetaSHA application that enables the simultaneous optimization of both computation and communication at run-time using flexible settings. These techniques optimize initialization, source/media partition and MPI-IO output in different ways to achieve optimal performance on the target machines. The resulting code is a factor of four faster than the orignial version. New MPI-I/O capabilities have been added for the accurate Staggered-Grid Split-Node (SGSN) method for dynamic rupture propagation in the velocity-stress staggered-grid finite difference scheme (Dalguer and Day, JGR, 2007), We use execution workflow across TeraGrid sites for managing the resulting data volumes. Our lessons learned indicate that minimizing time to solution is most critical, in particular when scheduling large scale simulations across supercomputer sites. The TeraShake platform has been ported to multiple architectures including TACC Dell lonestar and Abe, Cray XT3 Bigben and Blue Gene/L. Parallel efficiency of 96% with the PetaSHA application Olsen-AWM has been demonstrated on 40,960 Blue Gene/L processors at IBM TJ Watson Center. Notable

  5. Failure probability analysis of optical grid

    Science.gov (United States)

    Zhong, Yaoquan; Guo, Wei; Sun, Weiqiang; Jin, Yaohui; Hu, Weisheng

    2008-11-01

    Optical grid, the integrated computing environment based on optical network, is expected to be an efficient infrastructure to support advanced data-intensive grid applications. In optical grid, the faults of both computational and network resources are inevitable due to the large scale and high complexity of the system. With the optical network based distributed computing systems extensive applied in the processing of data, the requirement of the application failure probability have been an important indicator of the quality of application and an important aspect the operators consider. This paper will present a task-based analysis method of the application failure probability in optical grid. Then the failure probability of the entire application can be quantified, and the performance of reducing application failure probability in different backup strategies can be compared, so that the different requirements of different clients can be satisfied according to the application failure probability respectively. In optical grid, when the application based DAG (directed acyclic graph) is executed in different backup strategies, the application failure probability and the application complete time is different. This paper will propose new multi-objective differentiated services algorithm (MDSA). New application scheduling algorithm can guarantee the requirement of the failure probability and improve the network resource utilization, realize a compromise between the network operator and the application submission. Then differentiated services can be achieved in optical grid.

  6. SU-F-T-508: A Collimator-Based 3-Dimensional Grid Therapy Technique in a Small Animal Radiation Research Platform

    International Nuclear Information System (INIS)

    Jin, J; Kong, V; Zhang, H

    2016-01-01

    Purpose: Three dimensional (3D) Grid Therapy using MLC-based inverse-planning has been proposed to achieve the features of both conformal radiotherapy and spatially fractionated radiotherapy, which may deliver very high dose in a single fraction to portions of a large tumor with relatively low normal tissue dose. However, the technique requires relatively long delivery time. This study aims to develop a collimator-based 3D grid therapy technique. Here we report the development of the technique in a small animal radiation research platform. Methods: Similar as in the MLC-based technique, 9 non-coplanar beams in special channeling directions were used for the 3D grid therapy technique. Two specially designed grid collimators were fabricated, and one of them was selectively used to match the corresponding gantry/couch angles so that the grid opening of all 9 beams are met in the 3D space in the target. A stack of EBT3 films were used as 3D dosimetry to demonstrate the 3D grid-like dose distribution in the target. Three 1-mm beams were delivered to the stack of films in the area outside the target for alignment when all the films were scanned to reconstruct the 3D dosimtric image. Results: 3D film dosimetry showed a lattice-like dose distribution in the 3D target as well as in the axial, sagittal and coronal planes. The dose outside the target also showed a grid like dose distribution, and the average dose gradually decreased with the distance to the target. The peak to valley ratio was approximately 5:1. The delivery time was 7 minutes for 18 Gy peak dose, comparing to 6 minutes to deliver a 18-Gy 3D conformal plan. Conclusion: We have demonstrated the feasibility of the collimator-based 3D grid therapy technique which can significantly reduce delivery time comparing to MLC-based inverse planning technique.

  7. SU-F-T-508: A Collimator-Based 3-Dimensional Grid Therapy Technique in a Small Animal Radiation Research Platform

    Energy Technology Data Exchange (ETDEWEB)

    Jin, J; Kong, V; Zhang, H [Georgia Regents University, Augusta, GA (Georgia)

    2016-06-15

    Purpose: Three dimensional (3D) Grid Therapy using MLC-based inverse-planning has been proposed to achieve the features of both conformal radiotherapy and spatially fractionated radiotherapy, which may deliver very high dose in a single fraction to portions of a large tumor with relatively low normal tissue dose. However, the technique requires relatively long delivery time. This study aims to develop a collimator-based 3D grid therapy technique. Here we report the development of the technique in a small animal radiation research platform. Methods: Similar as in the MLC-based technique, 9 non-coplanar beams in special channeling directions were used for the 3D grid therapy technique. Two specially designed grid collimators were fabricated, and one of them was selectively used to match the corresponding gantry/couch angles so that the grid opening of all 9 beams are met in the 3D space in the target. A stack of EBT3 films were used as 3D dosimetry to demonstrate the 3D grid-like dose distribution in the target. Three 1-mm beams were delivered to the stack of films in the area outside the target for alignment when all the films were scanned to reconstruct the 3D dosimtric image. Results: 3D film dosimetry showed a lattice-like dose distribution in the 3D target as well as in the axial, sagittal and coronal planes. The dose outside the target also showed a grid like dose distribution, and the average dose gradually decreased with the distance to the target. The peak to valley ratio was approximately 5:1. The delivery time was 7 minutes for 18 Gy peak dose, comparing to 6 minutes to deliver a 18-Gy 3D conformal plan. Conclusion: We have demonstrated the feasibility of the collimator-based 3D grid therapy technique which can significantly reduce delivery time comparing to MLC-based inverse planning technique.

  8. Design of ACM system based on non-greedy punctured LDPC codes

    Science.gov (United States)

    Lu, Zijun; Jiang, Zihong; Zhou, Lin; He, Yucheng

    2017-08-01

    In this paper, an adaptive coded modulation (ACM) scheme based on rate-compatible LDPC (RC-LDPC) codes was designed. The RC-LDPC codes were constructed by a non-greedy puncturing method which showed good performance in high code rate region. Moreover, the incremental redundancy scheme of LDPC-based ACM system over AWGN channel was proposed. By this scheme, code rates vary from 2/3 to 5/6 and the complication of the ACM system is lowered. Simulations show that more and more obvious coding gain can be obtained by the proposed ACM system with higher throughput.

  9. Assessment of the Unstructured Grid Software TetrUSS for Drag Prediction of the DLR-F4 Configuration

    Science.gov (United States)

    Pirzadeh, Shahyar Z.; Frink, Neal T.

    2002-01-01

    An application of the NASA unstructured grid software system TetrUSS is presented for the prediction of aerodynamic drag on a transport configuration. The paper briefly describes the underlying methodology and summarizes the results obtained on the DLR-F4 transport configuration recently presented in the first AIAA computational fluid dynamics (CFD) Drag Prediction Workshop. TetrUSS is a suite of loosely coupled unstructured grid CFD codes developed at the NASA Langley Research Center. The meshing approach is based on the advancing-front and the advancing-layers procedures. The flow solver employs a cell-centered, finite volume scheme for solving the Reynolds Averaged Navier-Stokes equations on tetrahedral grids. For the present computations, flow in the viscous sublayer has been modeled with an analytical wall function. The emphasis of the paper is placed on the practicality of the methodology for accurately predicting aerodynamic drag data.

  10. Smart grid

    International Nuclear Information System (INIS)

    Choi, Dong Bae

    2001-11-01

    This book describes press smart grid from basics to recent trend. It is divided into ten chapters, which deals with smart grid as green revolution in energy with introduction, history, the fields, application and needed technique for smart grid, Trend of smart grid in foreign such as a model business of smart grid in foreign, policy for smart grid in U.S.A, Trend of smart grid in domestic with international standard of smart grid and strategy and rood map, smart power grid as infrastructure of smart business with EMS development, SAS, SCADA, DAS and PQMS, smart grid for smart consumer, smart renewable like Desertec project, convergence IT with network and PLC, application of an electric car, smart electro service for realtime of electrical pricing system, arrangement of smart grid.

  11. Reliability analysis in interdependent smart grid systems

    Science.gov (United States)

    Peng, Hao; Kan, Zhe; Zhao, Dandan; Han, Jianmin; Lu, Jianfeng; Hu, Zhaolong

    2018-06-01

    Complex network theory is a useful way to study many real complex systems. In this paper, a reliability analysis model based on complex network theory is introduced in interdependent smart grid systems. In this paper, we focus on understanding the structure of smart grid systems and studying the underlying network model, their interactions, and relationships and how cascading failures occur in the interdependent smart grid systems. We propose a practical model for interdependent smart grid systems using complex theory. Besides, based on percolation theory, we also study the effect of cascading failures effect and reveal detailed mathematical analysis of failure propagation in such systems. We analyze the reliability of our proposed model caused by random attacks or failures by calculating the size of giant functioning components in interdependent smart grid systems. Our simulation results also show that there exists a threshold for the proportion of faulty nodes, beyond which the smart grid systems collapse. Also we determine the critical values for different system parameters. In this way, the reliability analysis model based on complex network theory can be effectively utilized for anti-attack and protection purposes in interdependent smart grid systems.

  12. Influencing Factors and Development Trend Analysis of China Electric Grid Investment Demand Based on a Panel Co-Integration Model

    OpenAIRE

    Jinchao Li; Lin Chen; Yuwei Xiang; Jinying Li; Dong Peng

    2018-01-01

    Electric grid investment demand analysis is significant to reasonably arranging construction funds for the electric grid and reduce costs. This paper used the panel data of electric grid investment from 23 provinces of China between 2004 and 2016 as samples to analyze the influence between electric grid investment demand and GDP, population scale, social electricity consumption, installed electrical capacity, and peak load based on co-integration tests. We find that GDP and peak load have pos...

  13. Development of Monte Carlo-based pebble bed reactor fuel management code

    International Nuclear Information System (INIS)

    Setiadipura, Topan; Obara, Toru

    2014-01-01

    Highlights: • A new Monte Carlo-based fuel management code for OTTO cycle pebble bed reactor was developed. • The double-heterogeneity was modeled using statistical method in MVP-BURN code. • The code can perform analysis of equilibrium and non-equilibrium phase. • Code-to-code comparisons for Once-Through-Then-Out case were investigated. • Ability of the code to accommodate the void cavity was confirmed. - Abstract: A fuel management code for pebble bed reactors (PBRs) based on the Monte Carlo method has been developed in this study. The code, named Monte Carlo burnup analysis code for PBR (MCPBR), enables a simulation of the Once-Through-Then-Out (OTTO) cycle of a PBR from the running-in phase to the equilibrium condition. In MCPBR, a burnup calculation based on a continuous-energy Monte Carlo code, MVP-BURN, is coupled with an additional utility code to be able to simulate the OTTO cycle of PBR. MCPBR has several advantages in modeling PBRs, namely its Monte Carlo neutron transport modeling, its capability of explicitly modeling the double heterogeneity of the PBR core, and its ability to model different axial fuel speeds in the PBR core. Analysis at the equilibrium condition of the simplified PBR was used as the validation test of MCPBR. The calculation results of the code were compared with the results of diffusion-based fuel management PBR codes, namely the VSOP and PEBBED codes. Using JENDL-4.0 nuclide library, MCPBR gave a 4.15% and 3.32% lower k eff value compared to VSOP and PEBBED, respectively. While using JENDL-3.3, MCPBR gave a 2.22% and 3.11% higher k eff value compared to VSOP and PEBBED, respectively. The ability of MCPBR to analyze neutron transport in the top void of the PBR core and its effects was also confirmed

  14. Intrusion Prevention and Detection in Grid Computing - The ALICE Case

    CERN Document Server

    INSPIRE-00416173; Kebschull, Udo

    2015-01-01

    Grids allow users flexible on-demand usage of computing resources through remote communication networks. A remarkable example of a Grid in High Energy Physics (HEP) research is used in the ALICE experiment at European Organization for Nuclear Research CERN. Physicists can submit jobs used to process the huge amount of particle collision data produced by the Large Hadron Collider (LHC). Grids face complex security challenges. They are interesting targets for attackers seeking for huge computational resources. Since users can execute arbitrary code in the worker nodes on the Grid sites, special care should be put in this environment. Automatic tools to harden and monitor this scenario are required. Currently, there is no integrated solution for such requirement. This paper describes a new security framework to allow execution of job payloads in a sandboxed context. It also allows process behavior monitoring to detect intrusions, even when new attack methods or zero day vulnerabilities are exploited, by a Machin...

  15. gCube Grid services

    CERN Document Server

    Andrade, Pedro

    2008-01-01

    gCube is a service-based framework for eScience applications requiring collaboratory, on-demand, and intensive information processing. It provides to these communities Virtual Research Environments (VREs) to support their activities. gCube is build on top of standard technologies for computational Grids, namely the gLite middleware. The software was produced by the DILIGENT project and will continue to be supported and further developed by the D4Science project. gCube reflects within its name a three-sided interpretation of the Grid vision of resource sharing: sharing of computational resources, sharing of structured data, and sharing of application services. As such, gCube embodies the defining characteristics of computational Grids, data Grids, and virtual data Grids. Precisely, it builds on gLite middleware for managing distributed computations and unstructured data, includes dedicated services for managing data and metadata, provides services for distributed information retrieval, allows the orchestration...

  16. A Stackelberg Game Approach for Energy Outage-Aware Power Distribution of an Off-Grid Base Station over Multiple Retailers

    Directory of Open Access Journals (Sweden)

    Seung Hyun Jeon

    2018-03-01

    Full Text Available This paper investigates the problem of power distribution for an off-grid base station (BS that operates sustainably without an electrical grid. We consider that multiple retailers with heterogeneous renewable energy sources (RESs compete to maximize their revenues by individually setting the unit power price. Energy outages (EOs, which cause the power supply to fall below that which is sufficient for ensuring the traffic arrival rate required for the off-grid BS, critically affect the users’ service quality. To minimize EOs and operational expenditure (OPEX, the off-grid BS manages the power supply by reacting to the retailers’ pricing decisions. We analyze the economic benefits of power distribution to the off-grid BS from the perspective of the retailers’ pricing competition, by designing a hierarchical decision-making scheme as a multi-leader single-follower Stackelberg game. We derive a closed form expression for the optimal behavior of the off-grid BS and retailers, based on well-designed utility functions. Finally, numerical results demonstrate the proposed solution with its practical convergence time.

  17. The Construction of an Ontology-Based Ubiquitous Learning Grid

    Science.gov (United States)

    Liao, Ching-Jung; Chou, Chien-Chih; Yang, Jin-Tan David

    2009-01-01

    The purpose of this study is to incorporate adaptive ontology into ubiquitous learning grid to achieve seamless learning environment. Ubiquitous learning grid uses ubiquitous computing environment to infer and determine the most adaptive learning contents and procedures in anytime, any place and with any device. To achieve the goal, an…

  18. A Grid storage accounting system based on DGAS and HLRmon

    International Nuclear Information System (INIS)

    Cristofori, A; Fattibene, E; Veronesi, P; Gaido, L; Guarise, A

    2012-01-01

    Accounting in a production-level Grid infrastructure is of paramount importance in order to measure the utilization of the available resources. While several CPU accounting systems are deployed within the European Grid Infrastructure (EGI), storage accounting systems, stable enough to be adopted in a production environment are not yet available. As a consequence, there is a growing interest in storage accounting and work on this is being carried out in the Open Grid Forum (OGF) where a Usage Record (UR) definition suitable for storage resources has been proposed for standardization. In this paper we present a storage accounting system which is composed of three parts: a sensor layer, a data repository with a transport layer (Distributed Grid Accounting System - DGAS) and a web portal providing graphical and tabular reports (HLRmon). The sensor layer is responsible for the creation of URs according to the schema (described in this paper) that is currently being discussed within OGF. DGAS is one of the CPU accounting systems used within EGI, in particular by the Italian Grid Infrastructure (IGI) and some other National Grid Initiatives (NGIs) and projects. DGAS architecture is evolving in order to collect Usage Records for different types of resources. This improvement allows DGAS to be used as a ‘general’ data repository and transport layer. HLRmon is the web portal acting as an interface to DGAS. It has been improved to retrieve storage accounting data from the DGAS repository and create reports in an easy way. This is very useful not only for the Grid users and administrators but also for the stakeholders.

  19. GridCom, Grid Commander: graphical interface for Grid jobs and data management

    International Nuclear Information System (INIS)

    Galaktionov, V.V.

    2011-01-01

    GridCom - the software package for maintenance of automation of access to means of distributed system Grid (jobs and data). The client part, executed in the form of Java-applets, realises the Web-interface access to Grid through standard browsers. The executive part Lexor (LCG Executor) is started by the user in UI (User Interface) machine providing performance of Grid operations

  20. Price-based Energy Control for V2G Networks in the Industrial Smart Grid

    Directory of Open Access Journals (Sweden)

    Rong Yu

    2015-08-01

    Full Text Available The energy crisis and global warming call for a new industrial revolution in production and distribution of renewable energy. Distributed power generation will be well developed in the new smart electricity distribution grid, in which robust power distribution will be the key technology. In this paper, we present a new vehicle-to-grid (V2G network for energy transfer, in which distributed renewable energy helps the power grid balance demand and supply. Plug-in hybrid electric vehicles (PHEVs will act as transporters of electricity for distributed renewable energy dispatching. We formulate and analyze the V2G network within the theoretical framework of complex network. We also employ the generalized synchronization method to study the dynamic behavior of V2G networks. Furthermore, we develop a new price-based energy control method to stimulate the PHEV's behavior of charging and discharging. Simulation results indicate that the V2G network can achieve synchronization and each region is able to balance energy supply and demand through price-based control.