Journal articles on the topic 'Computational Grid'
To see the other types of publications on this topic, follow the link: Computational Grid.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Computational Grid.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Nikitina, A. V., A. E. Chistyakov, and A. M. Atayan. "NUMERICAL IMPLEMENTATION OF A PARALLEL ALGORITHM FOR SOLVING THE PROBLEM OF POLLUTANT TRANSPORT IN A RESERVOIR ON A HIGH-PERFORMANCE COMPUTER SYSTEM." Vestnik komp'iuternykh i informatsionnykh tekhnologii, no. 202 (April 2021): 27–36. http://dx.doi.org/10.14489/vkit.2021.04.pp.027-036.
Full textAbstract:
The purpose of this work is to create a software package for a distributed solution of the problem of transporting a pollutant in a reservoir with complex bathymetry and the presence of technological structures. An algorithm has been developed for the parallel solution of the problem of transporting a pollutant (pollutant) in a reservoir on a graphics accelerator controlled by the CUDA (Compute Unified Device Architecture) system; a comparative analysis of the operation of algorithms on a CPU (Central Processing Unit) and on a graphics accelerator GPU (Graphics Processing Unit) made it possible to evaluate their performance. The software implementation of the modules included in the complex is described, the main classes and implemented methods are documented. The results of numerical experiments showed that solving of pollutant transport’s problem based on the CUDA technology is ineffective for small grids (up to 100 ´ 100 computational nodes). In the case of large grids (1000 ´ 1000 computational nodes), the use of CUDA technology reduces the computation time by an order of magnitude. An analysis of the experiments carried out with the developed components of software showed that the maximum value of the ratio of the algorithm operating time that implements the set task of transferring matter in a shallow water on a GPU to the operating time of a similar algorithm on the CPU was 24.92 times, which is achieved on a grid of 1000 ´ 1000 computational nodes. Implementation of methods for decomposition of grid regions is proposed for solving computationally laborious problems of diffusion-convection, including the problem of transporting pollutants in a reservoir with complex bathymetry with technological objects that take into account the architecture and parameters of a MSC (Multiprocessor Computing System) located on the basis of the infrastructure facility of the STU (Scientific and Technological University) “Sirius” (Sochi, Russia). Consideration was made for such a property of a computing system as the time it takes to transmit and receive floating point data. An algorithm for the parallel solution of the task under the control of MPI (Message Passing Interface) technology has been developed, and its efficiency has been assessed. The acceleration values of the proposed algorithm are obtained depending on the number of involved computers (processors) and the size of the computational grid. The maximum number of computers used is 24, the maximum size of the computational grid was 10 000 ´ 10 000 computational nodes. The developed algorithm showed low efficiency for small computational grids (up to 100 ´ 100 computational nodes). In the case of large computational grids ( from 1000 1000 computational nodes), the use of MPI reduces the computation time by several times.
2
Goswami, Sukalyan, and Kuntal Mukherjee. "High Performance Fault Tolerant Resource Scheduling in Computational Grid Environment." International Journal of Web-Based Learning and Teaching Technologies 15, no. 1 (January 2020): 73–87. http://dx.doi.org/10.4018/ijwltt.2020010104.
Full textAbstract:
Virtual resources team up to create a computational grid, which is used in computation-intensive problem solving. A majority of these problems require high performance resources to compute and generate results, making grid computation another type of high performance computing. The optimization in computational grids relates to resource utilization which in turn is achieved by the proper distribution of loads among participating resources. This research takes up an adaptive resource ranking approach, and improves the effectiveness of NDFS algorithm by scheduling jobs in those ranked resources, thereby increasing the number of job deadlines met and service quality agreements met. Moreover, resource failure is taken care of by introducing a partial backup approach. The benchmark codes of Fast Fourier Transform and Matrix Multiplication are executed in a real test bed of a computational grid, set up by Globus Toolkit 5.2 for the justification of propositions made in this article.
3
Bernth, Henrik, and Chris Chapman. "A comparison of the dispersion relations for anisotropic elastodynamic finite-difference grids." GEOPHYSICS 76, no. 3 (May 2011): WA43—WA50. http://dx.doi.org/10.1190/1.3555530.
Full textAbstract:
Several staggered grid schemes have been suggested for performing finite-difference calculations for the elastic wave equations. In this paper, the dispersion relationships and related computational requirements for the Lebedev and rotated staggered grids for anisotropic, elastic, finite-difference calculations in smooth models are analyzed and compared. These grids are related to a popular staggered grid for the isotropic problem, the Virieux grid. The Lebedev grid decomposes into Virieux grids, two in two dimensions and four in three dimensions, which decouple in isotropic media. Therefore the Lebedev scheme will have twice or four times the computational requirements, memory, and CPU as the Virieux grid but can be used with general anisotropy. In two dimensions, the rotated staggered grid is exactly equivalent to the Lebedev grid, but in three dimensions it is fundamentally different. The numerical dispersion in finite-difference grids depends on the direction of propagation and the grid type and parameters. A joint numerical dispersion relation for the two grids types in the isotropic case is derived. In order to compare the computational requirements for the two grid types, the dispersion, averaged over propagation direction and medium velocity are calculated. Setting the parameters so the average dispersion is equal for the two grids, the computational requirements of the two grid types are compared. In three dimensions, the rotated staggered grid requires at least 20% more memory for the field data and at least twice as many number of floating point operations and memory accesses, so the Lebedev grid is more efficient and is to be preferred.
4
Kang, Ning, and Yuan Cao. "Research on Computational Fluid Dynamics with Effect of Grid Quality on the Accuracy of Simulated Results of Two Dimensional Low-Speed Parallel Flow." Applied Mechanics and Materials 685 (October 2014): 232–35. http://dx.doi.org/10.4028/www.scientific.net/amm.685.232.
Full textAbstract:
In the field of computational fluid dynamics, grid generation costs most of work. The accuracy and reliability of the simulated results depend directly on grid quality. The two dimensional parallel flow with low speed was used to study the effect of grid quality on simulated results. Several conclusions are obtained. The computational error decreases with the increase of domain size in flow direction. Too many grids in flow direction will lead to bigger round-off error, while too few grids will make it harder to catch the correct flow. The increase of grid quantity in the direction perpendicular to flow direction will decrease the computational error, but the effect is not obvious. Increasing the grid quantity in the area near the wall will decrease the computational error.
5
Coveney, Peter V. "Scientific Grid computing." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 363, no. 1833 (July 18, 2005): 1707–13. http://dx.doi.org/10.1098/rsta.2005.1632.
Full textAbstract:
We introduce a definition of Grid computing which is adhered to throughout this Theme Issue. We compare the evolution of the World Wide Web with current aspirations for Grid computing and indicate areas that need further research and development before a generally usable Grid infrastructure becomes available. We discuss work that has been done in order to make scientific Grid computing a viable proposition, including the building of Grids, middleware developments, computational steering and visualization. We review science that has been enabled by contemporary computational Grids, and associated progress made through the widening availability of high performance computing.
6
Miller, Russ, Naimesh Shah, Mark L. Green, William Furey, and Charles M. Weeks. "Shake-and-Bakeon the grid." Journal of Applied Crystallography 40, no. 5 (September 5, 2007): 938–44. http://dx.doi.org/10.1107/s0021889807034565.
Full textAbstract:
Computational and data grids represent an emerging technology that allows geographically and organizationally distributed resources (e.g.computing and storage resources) to be linked and accessed in a fashion that is transparent to the user, presenting an extension of the desktop for users whose computational, data and visualization needs extend beyond their local systems. The New York State Grid is an integrated computational and data grid that provides web-based access for users from around the world to computational, application and data storage resources. This grid is used in a ubiquitous fashion, where the users have virtual access to their data sets and applications, but do not need to be made aware of the details of the data storage or computational devices that are specifically employed. Two of the applications that users worldwide have access to on a variety of grids, including the New York State Grid, are theSnBandBnPprograms, which implement theShake-and-Bakemethod of molecular structure (SnB) and substructure (BnP) determination, respectively. In particular, through our grid portal (i.e.logging on to a web site),SnBhas been run simultaneously on all computational resources on the New York State Grid as well as on more than 1100 of the over 3000 processors available through the Open Science Grid.
7
Weller, Hilary, John Thuburn, and Colin J. Cotter. "Computational Modes and Grid Imprinting on Five Quasi-Uniform Spherical C Grids." Monthly Weather Review 140, no. 8 (August 1, 2012): 2734–55. http://dx.doi.org/10.1175/mwr-d-11-00193.1.
Full textAbstract:
Abstract Currently, most operational forecasting models use latitude–longitude grids, whose convergence of meridians toward the poles limits parallel scaling. Quasi-uniform grids might avoid this limitation. Thuburn et al. and Ringler et al. have developed a method for arbitrarily structured, orthogonal C grids called TRiSK, which has many of the desirable properties of the C grid on latitude–longitude grids but which works on a variety of quasi-uniform grids. Here, five quasi-uniform, orthogonal grids of the sphere are investigated using TRiSK to solve the shallow-water equations. Some of the advantages and disadvantages of the hexagonal and triangular icosahedra, a “Voronoi-ized” cubed sphere, a Voronoi-ized skipped latitude–longitude grid, and a grid of kites in comparison to a full latitude–longitude grid are demonstrated. It is shown that the hexagonal icosahedron gives the most accurate results (for least computational cost). All of the grids suffer from spurious computational modes; this is especially true of the kite grid, despite it having exactly twice as many velocity degrees of freedom as height degrees of freedom. However, the computational modes are easiest to control on the hexagonal icosahedron since they consist of vorticity oscillations on the dual grid that can be controlled using a diffusive advection scheme for potential vorticity.
8
Aloisio, Giovanni, Massimo Cafaro, Euro Blasi, and Italo Epicoco. "The Grid Resource Broker, A Ubiquitous Grid Computing Framework." Scientific Programming 10, no. 2 (2002): 113–19. http://dx.doi.org/10.1155/2002/969307.
Full textAbstract:
Portals to computational/data grids provide the scientific community with a friendly environment in order to solve large-scale computational problems. The Grid Resource Broker (GRB) is a grid portal that allows trusted users to create and handle computational/data grids on the fly exploiting a simple and friendly web-based GUI. GRB provides location-transparent secure access to Globus services, automatic discovery of resources matching the user's criteria, selection and scheduling on behalf of the user. Moreover, users are not required to learn Globus and they do not need to write specialized code or to rewrite their existing legacy codes. We describe GRB architecture, its components and current GRB features addressing the main differences between our approach and related work in the area.
9
Ha, Minho, Cheolung Cheong, Hanshin Seol, Bu-Geun Paik, Min-Jae Kim, and Young-Rae Jung. "Development of Efficient and Accurate Parallel Computation Algorithm Using Moving Overset Grids on Background Multi-Domains for Complex Two-Phase Flows." Applied Sciences 8, no. 10 (October 16, 2018): 1937. http://dx.doi.org/10.3390/app8101937.
Full textAbstract:
The goal of this study involves developing an efficient and accurate parallel computation method for two-phase flow problems including complex moving foreign bodies. The proposed parallel computing techniques are based on the moving body-fitted grids’ overset on background multidomains with grid-overlapping at their interface. First, the cavitation flow over the hemispherical head form is investigated using the two-phase flow solver, which is validated by comparing the numerical and experimental results. Subsequently, the parallel computing technique based on the multidomain method that divides the computational domain into several smaller subdomains is proposed to facilitate more efficient numerical simulations. At the interface of the subdomains, the grid-overlapping method is proposed for more accurate simulations. The illustrative computations indicate that the accuracy of the parallel computation combined with the grid-overlapping method on multidomains is identical to that of the serial computation based on a single block, albeit with a significant reduction in the computation time. Finally, the moving overset grid technique is combined with the background multidomain method and applied to simulate the gust flow that is generated by the pitching motions of the twin hydrofoils. The overset grid technique includes the following three sequential steps: hole-cutting, finding donor cells, and bilinear interpolation. The prediction results for the inflow gust generated by oscillating hydrofoils closely follow the measured results.
10
Guan, Steven, Ko-Tsung Hsu, and Parag V. Chitnis. "Fourier Neural Operator Network for Fast Photoacoustic Wave Simulations." Algorithms 16, no. 2 (February 19, 2023): 124. http://dx.doi.org/10.3390/a16020124.
Full textAbstract:
Simulation tools for photoacoustic wave propagation have played a key role in advancing photoacoustic imaging by providing quantitative and qualitative insights into parameters affecting image quality. Classical methods for numerically solving the photoacoustic wave equation rely on a fine discretization of space and can become computationally expensive for large computational grids. In this work, we applied Fourier Neural Operator (FNO) networks as a fast data-driven deep learning method for solving the 2D photoacoustic wave equation in a homogeneous medium. Comparisons between the FNO network and pseudo-spectral time domain approach were made for the forward and adjoint simulations. Results demonstrate that the FNO network generated comparable simulations with small errors and was orders of magnitude faster than the pseudo-spectral time domain methods (~26× faster on a 64 × 64 computational grid and ~15× faster on a 128 × 128 computational grid). Moreover, the FNO network was generalizable to the unseen out-of-domain test set with a root-mean-square error of 9.5 × 10−3 in Shepp–Logan, 1.5 × 10−2 in synthetic vasculature, 1.1 × 10−2 in tumor and 1.9 × 10−2 in Mason-M phantoms on a 64 × 64 computational grid and a root mean squared of 6.9 ± 5.5 × 10−3 in the AWA2 dataset on a 128 × 128 computational grid.
11
Abras, Jennifer N., C. Eric Lynch, and Marilyn J. Smith. "Computational Fluid Dynamics–Computational Structural Dynamics Rotor Coupling Using an Unstructured Reynolds-Averaged Navier–Stokes Methodology." Journal of the American Helicopter Society 57, no. 1 (January 1, 2012): 1–14. http://dx.doi.org/10.4050/jahs.57.012001.
Full textAbstract:
The focus of this paper is to discuss the unique challenges introduced through the use of unstructured grids in rotorcraft computational fluid dynamics (CFD)–computational structural dynamics (CSD) coupling. The use of unstructured grid methodology in CFD has been expanding because of the advantages in grid generation and modeling of complex configurations. However, the resulting amorphous distribution of the grid points on the rotor blade surface provides no information with regard to the orientation of the blade, in direct contrast to structured grid methodology that can take advantage of the ordered mapping of points to identify the orientation as well as simplifying airloads integration. A methodology has been developed and is described here, which now permits unstructured methods to be utilized for elastic rotary-wing simulations. This methodology is evaluated through comparison of the UH60A rotor with available flight test data for forward flight.
12
Bindle, Liam, Randall V. Martin, Matthew J. Cooper, Elizabeth W. Lundgren, Sebastian D. Eastham, Benjamin M. Auer, Thomas L. Clune, et al. "Grid-stretching capability for the GEOS-Chem 13.0.0 atmospheric chemistry model." Geoscientific Model Development 14, no. 10 (October 6, 2021): 5977–97. http://dx.doi.org/10.5194/gmd-14-5977-2021.
Full textAbstract:
Abstract. Modeling atmospheric chemistry at fine resolution globally is computationally expensive; the capability to focus on specific geographic regions using a multiscale grid is desirable. Here, we develop, validate, and demonstrate stretched grids in the GEOS-Chem atmospheric chemistry model in its high-performance implementation (GCHP). These multiscale grids are specified at runtime by four parameters that offer users nimble control of the region that is refined and the resolution of the refinement. We validate the stretched-grid simulation versus global cubed-sphere simulations. We demonstrate the operation and flexibility of stretched-grid simulations with two case studies that compare simulated tropospheric NO2 column densities from stretched-grid and cubed-sphere simulations to retrieved column densities from the TROPOspheric Monitoring Instrument (TROPOMI). The first case study uses a stretched grid with a broad refinement covering the contiguous US to produce simulated columns that perform similarly to a C180 (∼ 50 km) cubed-sphere simulation at less than one-ninth the computational expense. The second case study experiments with a large stretch factor for a global stretched-grid simulation with a highly localized refinement with ∼10 km resolution for California. We find that the refinement improves spatial agreement with TROPOMI columns compared to a C90 cubed-sphere simulation of comparable computational demands. Overall, we find that stretched grids in GEOS-Chem are a practical tool for fine-resolution regional- or continental-scale simulations of atmospheric chemistry. Stretched grids are available in GEOS-Chem version 13.0.0.
13
Weller, Hilary. "Controlling the Computational Modes of the Arbitrarily Structured C Grid." Monthly Weather Review 140, no. 10 (October 1, 2012): 3220–34. http://dx.doi.org/10.1175/mwr-d-11-00221.1.
Full textAbstract:
Abstract The arbitrarily structured C grid, Thuburn–Ringler–Skamarock–Klemp (TRiSK), is being used in the Model for Prediction Across Scales (MPAS) and is being considered by the Met Office for their next dynamical core. However, the hexagonal C grid supports a branch of spurious Rossby modes, which lead to erroneous grid-scale oscillations of potential vorticity (PV). It is shown how these modes can be harmlessly controlled by using upwind-biased interpolation schemes for PV. A number of existing advection schemes for PV are tested, including that used in MPAS, and none are found to give adequate results for all grids and all cases. Therefore a new scheme is proposed; continuous, linear-upwind stabilized transport (CLUST), a blend between centered and linear-upwind with the blend dependent on the flow direction with respect to the cell edge. A diagnostic of grid-scale oscillations is proposed that gives further discrimination between schemes than using potential enstrophy alone. Indeed, some schemes are found to destroy potential enstrophy while grid-scale oscillations grow. CLUST performs well on hexagonal-icosahedral grids and unrotated skipped latitude–longitude grids of the sphere for various shallow-water test cases. Despite the computational modes, the hexagonal icosahedral grid performs well since these modes are easy and harmless to filter. As a result, TRiSK appears to perform better than a spectral shallow-water model.
14
AUSTIN, MELANIE E., and N. ROSS CHAPMAN. "THE USE OF TESSELLATION IN THREE-DIMENSIONAL PARABOLIC EQUATION MODELING." Journal of Computational Acoustics 19, no. 03 (September 2011): 221–39. http://dx.doi.org/10.1142/s0218396x11004328.
Full textAbstract:
A full three-dimensional parabolic equation model (MONM3D) has been developed that incorporates techniques that reduce the required number of model grid points and reduces computation time. The concept of tessellation is implemented in MONM3D, which allows the number of radial paths in the model grid to vary with range from the source, reducing the number of computational points in the horizontal plane. This design establishes a grid layout that is both numerically and computationally desirable. A benchmark test case is used to illustrate the accuracy and efficiency of the model.
15
Kalmykov, S. P. "Effect of computational grid cell size and heterogeneity of computing area for estimated fire detection time." Pozharovzryvobezopasnost/Fire and Explosion Safety 31, no. 4 (September 28, 2022): 56–64. http://dx.doi.org/10.22227/0869-7493.2022.31.04.56-64.
Full textAbstract:
Introduction. In Russia, based on the provisions of the current regulatory documents, the time for the start of evacuation for a room in which a fire broke out is determined depending on the area of the room. According to some authors, the time of the start of the evacuation of people is a combination of “technical”, which includes the time of detection of a fire, and “psychophysical”, determined by the behavioral and organizational characteristics of the people who make it up. The fire detection time is currently not taken into account.Purpose. Evaluation of the influence of the size of the cells of the computational grid and the inhomogeneity of the computational domain on the estimated time of fire detection.Aims. 1. Establish the qualitative nature of the influence of the size of the cells of the computational grid and the inhomogeneity of the computational domain on the estimated time of fire detection.2. Offer recommendations for determining the estimated time of fire detection.Methods. For research, computer simulation methods were used using the Fire Dynamics Simulator software package.Results and discussion. The use of grids with different cell sizes can significantly reduce the number of cells in the computational domain and, as a result, the computation time. However, this leads to rather contradictory results. The minimum time values are reduced by almost 3–4 times compared to a homogeneous computational grid, and the maximum time increases by 2 times.Conclusions. 1. The size of the cells of the computational grid and the inhomogeneity of the computational domain have a significant impact on the time of fire detection.2. A sufficiently large spread in the values of the estimated fire detection time may indicate an unreliable estimate of the total time for the start of evacuation and incorrect conclusions about the safe evacuation of people and/or the probability of evacuation of people.3. For a correct estimate of the evacuation start time, taken into account the estimated fire detection time, it is recommended to use homogeneous computational grids with cell sizes not exceeding 0.25 m.
16
Bilbao-Castro, J. R., R. Marabini, J. M. Carazo, I. Garcia, and J. J. Fernandez. "THE POTENTIAL OF GRID COMPUTING IN THREE-DIMENSIONAL ELECTRON MICROSCOPY." Parallel Processing Letters 14, no. 02 (June 2004): 151–62. http://dx.doi.org/10.1142/s0129626404001805.
Full textAbstract:
This article describes a potential application of grid computing in structural biology. Three-dimensional electron microscopy allows the investigation of biological structures over a wide range of sizes, from cells to single macromolecules. Knowledge of the structure is critical to understanding the function of biological specimens. However, high resolution structure determination is computationally intensive. This contribution analyzes the potential benefits of grid computing in this field, and draws the conclusion that there are excellent opportunities to take advantage of computational grids.
17
Raza, Zahid, and Deo P. Vidyarthi. "Reliability Based Scheduling Model (RSM) for Computational Grids." International Journal of Distributed Systems and Technologies 2, no. 2 (April 2011): 20–37. http://dx.doi.org/10.4018/jdst.2011040102.
Full textAbstract:
Computational Grid attributed with distributed load sharing has evolved as a platform to large scale problem solving. Grid is a collection of heterogeneous resources, offering services of varying natures, in which jobs are submitted to any of the participating nodes. Scheduling these jobs in such a complex and dynamic environment has many challenges. Reliability analysis of the grid gains paramount importance because grid involves a large number of resources which may fail anytime, making it unreliable. These failures result in wastage of both computational power and money on the scarce grid resources. It is normally desired that the job should be scheduled in an environment that ensures maximum reliability to the job execution. This work presents a reliability based scheduling model for the jobs on the computational grid. The model considers the failure rate of both the software and hardware grid constituents like application demanding execution, nodes executing the job, and the network links supporting data exchange between the nodes. Job allocation using the proposed scheme becomes trusted as it schedules the job based on a priori reliability computation.
18
Kaushik, Achal, and Deo P. Vidyarthi. "A Cooperative Cell Model in Computational Mobile Grid." International Journal of Business Data Communications and Networking 8, no. 1 (January 2012): 19–36. http://dx.doi.org/10.4018/jbdcn.2012010102.
Full textAbstract:
Computation in the mobile grid nodes under the cellular network environment requires an efficient management of wireless channels along with the user mobility. Due to random movement of the mobile devices, the load over the cells in terms of initiation of new computation or carryover computation (handoff) may vary dynamically. This may result in non-availability of free channels for Inter-task communication leading in the drop of carryover computation or to initiate the new computation in the current cell. The proposed work designs a model by instigating substantive cooperation among underutilized and the overloaded cells, considering importance to the frequency reuse and assigning priority to the on-going computation in the computational mobile grid. The model seeks cooperation by grouping the cells in different sizes to reduce the blocking and dropping of the computation. Blocking of the communication is very serious in computational mobile grid environment as the drop may result in the termination of the computation. The model aims at minimizing the Call Block Probability (CBP) and Call Drop Probability (CDP) in the mobile grid by making the clusters of different sizes. A simulation experiment to evaluate the performance of the proposed model reveals the effectiveness of this model.
19
Morikawa, Go, and Ichiro Kimura. "Numerical analysis of flood with a double grid model." E3S Web of Conferences 40 (2018): 05042. http://dx.doi.org/10.1051/e3sconf/20184005042.
Full textAbstract:
The objective of this study is to verify the validity of a hyper grid type (double grid model) computational model, for calculating flood flows with inundations. Nowadays, detailed information of the bathymetry is available due to improved measurement techniques, such as LP data. However, the number of grid cells used in the computation is limited because of the limitation of computational infrastructures. A double grid approach based on the model proposed by Volp et. al.(2013) is employed to overcome this problem.This model directly uses the high resolution topographic data though the discretization of the governing equations are made on coarser grid. The computational results showed that the present numerical model can compute the large scale flood phenomena efficiently and accurately.
20
NANDAGOPAL, MALARVIZHI, S. GAJALAKSHMI, and V. RHYMEND UTHARIARAJ. "SCHEDULING WITH JOB CHECKPOINT IN COMPUTATIONAL GRID ENVIRONMENT." International Journal of Modeling, Simulation, and Scientific Computing 02, no. 03 (September 2011): 299–316. http://dx.doi.org/10.1142/s1793962311000517.
Full textAbstract:
Computational grids have the potential for solving large-scale scientific applications using heterogeneous and geographically distributed resources. In addition to the challenges of managing and scheduling these applications, reliability challenges arise because of the unreliable nature of grid infrastructure. Two major problems that are critical to the effective utilization of computational resources are efficient scheduling of jobs and providing fault tolerance in a reliable manner. This paper addresses these problems by combining the checkpoint replication based fault tolerance mechanism with minimum total time to release (MTTR) job scheduling algorithm. TTR includes the service time of the job, waiting time in the queue, transfer of input and output data to and from the resource. The MTTR algorithm minimizes the response time by selecting a computational resource based on job requirements, job characteristics, and hardware features of the resources. The fault tolerance mechanism used here sets the job checkpoints based on the resource failure rate. If resource failure occurs, the job is restarted from its last successful state using a checkpoint file from another grid resource. Globus ToolKit is used as the grid middleware to set up a grid environment and evaluate the performance of the proposed approach. The monitoring tools Ganglia and Network Weather Service are used to gather hardware and network details, respectively. The experimental results demonstrate that, the proposed approach effectively schedule the grid jobs with fault-tolerant way thereby reduces TTR of the jobs submitted in the grid. Also, it increases the percentage of jobs completed within specified deadline and making the grid trustworthy.
21
Gou, Mengjiao, Bohua Liu, Xiaomao Sun, and Yuli Ma. "Computational fluid dynamics grid technology development." Frontiers in Computing and Intelligent Systems 1, no. 3 (October 25, 2022): 61–64. http://dx.doi.org/10.54097/fcis.v1i3.2110.
Full textAbstract:
This paper reviews the development of computational fluid dynamics, especially computational aerodynamics. This paper summarizes the achievements of CFD in grid technology, analyzes the existing problems and perplexities, and prospects its development trend. The CFD grid technology includes structured grid, unstructured grid, hybrid grid and overlapping grid.
22
Cui, Pengcheng, Bin Li, Jing Tang, Jiangtao Chen, and Youqi Deng. "A modified adjoint-based grid adaptation and error correction method for unstructured grid." Modern Physics Letters B 32, no. 12n13 (May 10, 2018): 1840020. http://dx.doi.org/10.1142/s0217984918400201.
Full textAbstract:
Grid adaptation is an important strategy to improve the accuracy of output functions (e.g. drag, lift, etc.) in computational fluid dynamics (CFD) analysis and design applications. This paper presents a modified robust grid adaptation and error correction method for reducing simulation errors in integral outputs. The procedure is based on discrete adjoint optimization theory in which the estimated global error of output functions can be directly related to the local residual error. According to this relationship, local residual error contribution can be used as an indicator in a grid adaptation strategy designed to generate refined grids for accurately estimating the output functions. This grid adaptation and error correction method is applied to subsonic and supersonic simulations around three-dimensional configurations. Numerical results demonstrate that the sensitive grids to output functions are detected and refined after grid adaptation, and the accuracy of output functions is obviously improved after error correction. The proposed grid adaptation and error correction method is shown to compare very favorably in terms of output accuracy and computational efficiency relative to the traditional featured-based grid adaptation.
23
Lesyng, Bogdan, Piotr Bała, and Dietmar Erwin. "EUROGRID—European computational grid testbed." Journal of Parallel and Distributed Computing 63, no. 5 (May 2003): 590–96. http://dx.doi.org/10.1016/s0743-7315(03)00005-4.
Full text
24
Giocomo, Lisa M., May-Britt Moser, and Edvard I. Moser. "Computational Models of Grid Cells." Neuron 71, no. 4 (August 2011): 589–603. http://dx.doi.org/10.1016/j.neuron.2011.07.023.
Full text
25
Agarwal, A., M. Ahmed, A. Berman, B. L. Caron, A. Charbonneau, D. Deatrich, R. Desmarais, et al. "GridX1: A Canadian computational grid." Future Generation Computer Systems 23, no. 5 (June 2007): 680–87. http://dx.doi.org/10.1016/j.future.2006.12.006.
Full text
26
Huedo, Eduardo, Ugo Bastolla, Ruben S. Montero, and Ignacio M. Llorente. "Computational proteomics on the grid." New Generation Computing 22, no. 2 (June 2004): 191–92. http://dx.doi.org/10.1007/bf03040959.
Full text
27
Casulli, Vincenzo. "Computational grid, subgrid, and pixels." International Journal for Numerical Methods in Fluids 90, no. 3 (January 27, 2019): 140–55. http://dx.doi.org/10.1002/fld.4715.
Full text
28
Richard, R. J. A., Ajay Anant Joshi, and C. Eswaran. "Implementation of Computational Grid Services in Enterprise Grid Environments." American Journal of Applied Sciences 5, no. 11 (November 1, 2008): 1442–47. http://dx.doi.org/10.3844/ajassp.2008.1442.1447.
Full text
29
Zürcher, Bruno K. "Fast approximate Barnes interpolation: illustrated by Python-Numba implementation fast-barnes-py v1.0." Geoscientific Model Development 16, no. 6 (March 27, 2023): 1697–711. http://dx.doi.org/10.5194/gmd-16-1697-2023.
Full textAbstract:
Abstract. Barnes interpolation is a method that is widely used in geospatial sciences like meteorology to remodel data values recorded at irregularly distributed points into a representative analytical field. When implemented naively, the effort to calculate Barnes interpolation depends on the product of the number of sample points N and the number of grid points W×H, resulting in a computational complexity of O(N⋅W⋅H). In the era of highly resolved grids and overwhelming numbers of sample points, which originate, e.g., from the Internet of Things or crowd-sourced data, this computation can be quite demanding, even on high-performance machines. This paper presents new approaches of how very good approximations of Barnes interpolation can be implemented using fast algorithms that have a computational complexity of O(N+W⋅H). Two use cases in particular are considered, namely (1) where the used grid is embedded in the Euclidean plane and (2) where the grid is located on the unit sphere.
30
Šimon, Marek, Ladislav Huraj, and Vladimír Siládi. "Analysis of performance bottleneck of P2P grid applications." Journal of Applied Mathematics, Statistics and Informatics 9, no. 2 (December 1, 2013): 5–11. http://dx.doi.org/10.2478/jamsi-2013-0008.
Full textAbstract:
Abstract The OurGrid distributed environment is an open source grid middleware that enables the creation of P2P computational grids to speed up the execution of bag-of-tasks applications. Bag-of-tasks is an application model composed of several independent tasks not communicating with each other during their execution, tolerating network delays and faults. The paper shows that the main advantage to avoid bottlenecks is if the data gets larger or computations become more complex and the conclusion is made based on the presented measurements. Understanding such patterns sheds an insightful light on performance bottlenecks and design tradeoffs for P2P Grid applications
31
Don, Wai-Sun, Antonio de Gregorio, Jean-Piero Suarez, and Gustaaf B. Jacobs. "Assessing the Performance of a Three Dimensional Hybrid Central-WENO Finite Difference scheme with Computation of a Sonic Injector in Supersonic Cross Flow." Advances in Applied Mathematics and Mechanics 4, no. 06 (December 2012): 719–36. http://dx.doi.org/10.4208/aamm.12-12s03.
Full textAbstract:
AbstractA hybridization of a high order WENO-Zfinite difference scheme and a high order central finite difference method for computation of the two-dimensional Euler equations first presented in [B. Costa and W. S. Don, J. Comput. Appl. Math., 204(2) (2007)] is extended to three-dimensions and for parallel computation. The Hybrid scheme switches dynamically from a WENO-Zscheme to a central scheme at any grid location and time instance if the flow is sufficiently smooth and vice versa if the flow is exhibiting sharp shock-type phenomena. The smoothness of the flow is determined by a high order multi-resolution analysis. The method is tested on a benchmark sonic flow injection in supersonic cross flow. Increase of the order of the method reduces the numerical dissipation of the underlying schemes, which is shown to improve the resolution of small dynamic vortical scales. Shocks are captured sharply in an essentially non-oscillatory manner via the high order shock-capturing WENO-Zscheme. Computations of the injector flow with a WENO-Zscheme only and with the Hybrid scheme are in very close agreement. Thirty percent of grid points require a computationally expensive WENO-Zscheme for high-resolution capturing of shocks, whereas the remainder of grid points may be solved with the computationally more affordable central scheme. The computational cost of the Hybrid scheme can be up to a factor of one and a half lower as compared to computations with a WENO-Zscheme only for the sonic injector benchmark.
32
Saleh, Ahmed I. "A Novel System Oriented Scheduler for Avoiding Haste Problem in Computational Grids." International Journal of Grid and High Performance Computing 3, no. 1 (January 2011): 21–44. http://dx.doi.org/10.4018/jghpc.2011010102.
Full textAbstract:
Scheduling is an important issue that must be handled carefully to realize the “Just login to compute” principle introduced by computational grids. Current grid schedulers suffer from the haste problem, which is the inability to schedule all tasks successfully. Accordingly, some tasks fail to complete execution as they are allocated to unsuitable workers. Others may not start execution as suitable workers are previously allocated to other tasks. This paper introduces the scheduling haste problem and presents a novel high throughput grid scheduler. The proposed scheduler selects the most suitable worker to execute an input grid task. Hence, it minimizes the turnaround time for a set of grid tasks. Moreover, the scheduler is system oriented and avoids the scheduling haste problem. Experimental results show that the proposed scheduler outperforms traditional grid schedulers as it introduces better scheduling efficiency.
33
Zhang, Wensheng, and Hui Zheng. "A multiscale method for wave propagation in 3D heterogeneous poroelastic media." GEOPHYSICS 84, no. 4 (July 1, 2019): T237—T257. http://dx.doi.org/10.1190/geo2018-0482.1.
Full textAbstract:
A new multiscale method for wave simulation in 3D heterogeneous poroelastic media is developed. Wave propagation in inhomogeneous media involves many different scales of media. The physical parameters in the real media usually vary greatly within a very small scale. For the direct numerical methods for wave simulation, a refined grid is required in mesh generation to maintain the match between the mesh size and the material variations in the spatial scale. This greatly increases the computational cost and computer memory requirements. The multiscale method can overcome this difficulty due to the scale difference. The basic idea of our multiscale method is to construct computational schemes on two sets of meshes, i.e., coarse grids and fine grids. The finite-volume method is applied on the coarse grids, whereas the multiscale basis functions are computed with the finite-element method by solving a local problem on the fine grids. Moreover, the local problem only needs to be solved once before time stepping. This allows us to use a coarse grid while still capturing the information of the physical property variations in the small scale. Therefore, it has better accuracy than the single-scale method when they use the same coarse grids. The theoretical method and the dispersion analysis are investigated. Numerical computations with the perfectly matched layer boundary conditions are completed for 3D inhomogeneous poroelastic models with randomly distributed small scatterers. The results indicate that our multiscale method can effectively simulate wave propagation in 3D heterogeneous poroelastic media with a significant reduction in computation cost.
34
Kornilina, Marina Andreyevna, and Mikhail Vladimirovich Yakobovskiy. "Estimation of computational overheads for calculations on locally refined meshes." Keldysh Institute Preprints, no. 102 (2022): 1–36. http://dx.doi.org/10.20948/prepr-2022-102.
Full textAbstract:
A method for presenting grid data and algorithms for their processing when performing calculations on locally refined adaptive grids is considered. Estimates are obtained of the dependence of the number of operations and computational overheads on such parameters as the size of the base regular grid, the depth of refinement, and the number of processors. Algorithms for dynamic load balancing of processors, which provide a low level of overhead costs, are considered.
35
Petcu, Dana, Marcin Paprzycki, and Diana Dubu. "Design and Implementation of a Grid Extension for Maple." Scientific Programming 13, no. 2 (2005): 137–49. http://dx.doi.org/10.1155/2005/653638.
Full textAbstract:
One of the important issues facing the development of the grid as a computational framework of the future is availability of grid-enabled software. In this context, we discuss possible approaches to constructing a grid-enabled version of a computer algebra system. Our case study involves Maple: the proposed Maple2g package allows the connection between Maple and the computational grids based on the Globus Toolkit. We present the design of the Maple2g package and follow with a detailed discussion of its implementation. Finally, we illustrate performance of Maple2g in a number of experiments.
36
HEINZLREITER, PAUL, and DIETER KRANZLMÜLLER. "VISUALIZATION SERVICES ON THE GRID: THE GRID VISUALIZATION KERNEL." Parallel Processing Letters 13, no. 02 (June 2003): 135–48. http://dx.doi.org/10.1142/s0129626403001203.
Full textAbstract:
Two important tools of today's science and engineering are computational grids and visualization. While grid infrastructures offer a means to process large amounts of data across different, possibly distant resources, visualization aids in understanding the meaning of data. The Grid Visualization Kernel (GVK) addresses the connection of grid applications and visualization clients on the grid. The visualization capabilities of GVK are provided as flexible grid services via dedicated interfaces and protocols, while GVK itself relies on Globus services to implement the functionality of the visualization pipeline. This paper describes the concept of GVK and its core functionality for grid visualization services, and discusses how to use visualization in the grid environment.
37
Benedict, Shajulin, Rejitha R. S, and V. Vasudevan. "An Evolutionary Hybrid Scheduling Algorithm for Computational Grids." Journal of Advanced Computational Intelligence and Intelligent Informatics 12, no. 5 (September 20, 2008): 479–84. http://dx.doi.org/10.20965/jaciii.2008.p0479.
Full textAbstract:
Grids promote user collaboration through flexible, coordinated sharing of distributed resources to solve a single large problem. Grid scheduling, similar to resource discovery and monitoring, is inherently more complex in Grid environments. We propose two approaches for solving Grid scheduling problems with the simultaneous objectives of maximizing the number of workflow executions and minimizing the waiting time variance among tasks of each workflow. One is the multiple objective Niched Pareto Genetic Algorithm (NPGA) that involves evolution during a comprehensive search and work on multiple solutions. After the Genetic search, we strengthen the search using Simulated Annealing as a local search meta-heuristic. For comparison, we evaluate other scheduling, such as, Tabu Search (TS), Simulated annealing (SA), and Discrete Particle Swarm Optimization (Discrete PSO). Results show that our proposed evolutionary Hybrid scheduling involving NPGA with an SA search, works better than other scheduling in considering workflow execution time within a deadline and waiting time variance in tasks with minimal iterations.
38
Allahyari, Majid, Vahid Esfahanian, and Kianoosh Yousefi. "The Effects of Grid Accuracy on Flow Simulations: A Numerical Assessment." Fluids 5, no. 3 (July 10, 2020): 110. http://dx.doi.org/10.3390/fluids5030110.
Full textAbstract:
High-quality, accurate grid generation is a critical challenge in the computational simulation of fluid flows around complex geometries. In particular, the accuracy of the grids is an effective factor in order to achieve a successful numerical simulation. In the current study, we present a series of systematic numerical simulations for fluid flows around a NACA 0012 airfoil using different computational grid generation techniques, including the standard second-order, fourth-order compact, and Theodorsen transformation approaches, to assess the effects of grid accuracy on the flow solutions. The flow solvers are based on the second- and fourth-order schemes for spatial discretizations and Beam-Warming linearization method for time advancement. The obtained grids, as well as the metrics and the corresponding numerical flow solution for each grid generation technique, are compared and studied in detail. It is demonstrated that the quality and orthogonality of the grids is improved by using the fourth-order compact scheme. Moreover, the numerical assessment showed that the accuracy and the quality of the grids directly influence the numerical flow solutions. Finally, the higher-order accurate flow solvers are found to be more sensitive to the accuracy of the generated grid.
39
Aparna, K., K. Karthik, and K. N. Seetharamu. "Natural Convection Flows in Porous Square Enclosures with Different Aspect Ratios." Applied Mechanics and Materials 592-594 (July 2014): 1657–61. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.1657.
Full textAbstract:
Natural convection is studied numerically using finite element based computational procedure. The enclosure used for flow and heat transfer analysis has been bounded by adiabatic top wall, constant temperature cold vertical walls and a horizontal bottom wall. The grid independent study has been made with different grids to yield consistent values. Different grid sizes 30x30, 40x40, 50x50 uniform meshes have been studied. Study shows the convergence of average Nusselt number for a grid size of 41x41. Hence a grid size of 40x40 is used in all computations. Nusselt numbers are computed for different Rayleigh’s numbers (Ra) and aspect ratios of 1,2 and 3. Results are presented in the form of streamlines, isotherm plots and average Nusselt number. The average Nusselt numbers increase with Rayleigh number and for a given Ra, increase in Nu is obtained with increase in aspect ratio for bottom wall.
40
Xu, Zhiyu, Yonghua Tan, and Xiaoming Li. "Wavelet Methods and Adaptive Grids in One-Dimensional Movable Boundary Problems." Mathematical Problems in Engineering 2020 (March 9, 2020): 1–10. http://dx.doi.org/10.1155/2020/2545292.
Full textAbstract:
Adaptive wavelet collocation methods use wavelet transform and filtering to generate adaptive grids. However, if the boundary moves, the grid becomes aberrant. It baffles wavelet transform and makes the adaptive wavelet methods lose advantages on computational efficiency. This paper develops a series of methods or skills to effectively perform wavelet transform and to generate adaptive grids for one-dimensional movable boundary problems. The methods remain the original inner grid points and keep the grid in the original-nested structure, in order to remain scanty during the whole computing process. For boundary extending, the adaptive wavelet program begins to run on the very new grid beyond the original boundary once it reaches a nested structure, which is called the Intermittent Adaptive Method as a consequence. If the boundary extends tremendously, the new nested grids can be combined to a greater nested grid for further efficiency, which is named the Grid Combine Method. While for boundary contracting, a fictitious boundary is addressed to replace the original boundary that will recede, so wavelet transform can be successfully performed on the original nested grid. Finally, two numerical tests, local features moving and gas gun, were resolved and discussed to show the evolution process of the adaptive grids with the boundaries moving. For boundary contracting, the valid points decrease because the computation domain recedes; while for boundary extending, the valid point numbers vary between a range that almost remains unchanged.
41
Ghosh, Tarun Kumar, and Sanjoy Das. "Efficient Job Scheduling in Computational Grid Systems Using Wind Driven Optimization Technique." International Journal of Applied Metaheuristic Computing 9, no. 1 (January 2018): 49–59. http://dx.doi.org/10.4018/ijamc.2018010104.
Full textAbstract:
Computational Grid has been employed for solving complex and large computation-intensive problems with the help of geographically distributed, heterogeneous and dynamic resources. Job scheduling is a vital and challenging function of a computational Grid system. Job scheduler has to deal with many heterogeneous computational resources and to take decisions concerning the dynamic, efficient and effective execution of jobs. Optimization of the Grid performance is directly related with the efficiency of scheduling algorithm. To evaluate the efficiency of a scheduling algorithm, different parameters can be used, the most important of which are makespan and flowtime. In this paper, a very recent evolutionary heuristic algorithm known as Wind Driven Optimization (WDO) is used for efficiently allocating jobs to resources in a computational Grid system so that makespan and flowtime are minimized. In order to measure the efficacy of WDO, Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) are considered for comparison. This study proves that WDO produces best results.
42
Martynenko, S. I. "Remarks on Generation of the Orthogonal Structured Grids." Herald of the Bauman Moscow State Technical University. Series Natural Sciences, no. 82 (2019): 16–26. http://dx.doi.org/10.18698/1812-3368-2019-1-16-26.
Full textAbstract:
Grid generation techniques have contributed significantly toward the application of mathematical modeling in large-scale engineering problems. The structured grids have the advantage that very robust and parallel computational algorithms have been proposed for solving (initial-)boundary value problems. Orthogonal grids make it possible to simplify an approximation of the differential equations and to increase computation accuracy. Opportunity of the orthogonal structured grid generation for solving two- and three-dimensional (initial-)boundary value problems is analyzed in the article in assumption that isolines or isosurfaces of d (=2,3) functions form this grid. Condition of the isolines/isosurfaces orthogonality is used for formulation of the boundary value problems, the solutions of which will be form the orthogonal grid. A differential substitution is proposed to formulate the boundary value problems directly from the orthogonality condition of the grid. The substitution leads to the general partial differrential equations with undetermined coefficients. In the two-dimensional case, it is shown that the orthogonal grid generation is equivalent to the solution of partial differential equations of either elliptic or hyperbolic type. In three-dimensional domains, an orthogonal grid can be generated only in special cases. The obtained results are useful for mathematical modeling of the complex physicochemical processes in the technical devices
43
Xu, Lin, Yong-Hong Tang, Wei Pu, and Yang Han. "Hybrid electromechanical-electromagnetic simulation to SVC controller based on ADPSS platform." Journal of Energy in Southern Africa 25, no. 4 (December 19, 2014): 112–22. http://dx.doi.org/10.17159/2413-3051/2014/v25i4a2244.
Full textAbstract:
To test the dynamic performance and damping features of a static var compensator (SVC) controller accurately in large-scale interconnected AC/DC hybrid power systems, it is of vital significance to build the detailed electromagnetic transient model. However, it is unrealistic and time-consuming to build the detailed models of all the devices in the actual large-scale power grid. Utilizing the hybrid simulation function in the advanced digital power system simulator (ADPSS) and by dividing the large-scale power grid into the electromagnetic transient sub-grids and electromechanical sub-grids, the computation speed of real-time simulation is remarkably enhanced by the parallel computational capabilities of digital simulator. The SVC controller and the nearby substation are modelled in the electromagnetic transient sub-grid, and the residue sub-networks are modelled in the electromechanical sub-grid. This paper focuses on the mechanism of the hybrid electromechanical and electromagnetic simulation, the detailed modelling and the ADPSS-based digital closed-loop test methodologies of the SVC controller. Eventually, the validity and effectiveness of the modelling and control methods are confirmed by the experimental results.
44
Lee, Minhyung, Gwanyong Park, Changyoung Park, and Changmin Kim. "Improvement of Grid Independence Test for Computational Fluid Dynamics Model of Building Based on Grid Resolution." Advances in Civil Engineering 2020 (December 23, 2020): 1–11. http://dx.doi.org/10.1155/2020/8827936.
Full textAbstract:
Computational fluid dynamics (CFD) is being used in various research fields on the building environment. Target space of the CFD model is divided into a finite number of grids for numerical analysis. Therefore, an optimal grid design is required to obtain accurate results. The grid independence test is generally performed to design an optimal grid. However, given that there is no standardized procedure for gird independence test, most depend on the researcher’s experience and knowledge. In the conventional method, the subjective judgment of the researcher affected the selection of the grid conditions and the criteria for the optimal grid. It can lead to a decrease in the reliability of the simulation results by poor grid design. This study proposed a grid independence test method that applies the grid resolution to improve the conventional method. The grid resolution was calculated by applying the characteristic length. CV(RMSE) and R2 were applied as the criteria for optimal grid. A case study was conducted to evaluate the adequacy of the proposed method. As the characteristic length increased, the optimal grid resolution increased. In particular, for a characteristic length of 0.7 or more, the optimal grid resolution was evaluated as 24. The grid convergence index (GCI) was calculated to verify the suitability of the proposed method. As a result, all of the optimal grid resolution derived from the proposed method was evaluated as the optimal condition.
45
Wang, Bingzhu, Edward S. Krebes, and Dhananjay Ravat. "High-precision potential-field and gradient-component transformations and derivative computations using cubic B-splines." GEOPHYSICS 73, no. 5 (September 2008): I35—I42. http://dx.doi.org/10.1190/1.2953291.
Full textAbstract:
Potential-field and gradient-component transformations and derivative computations are necessary for many techniques of data enhancement, direct interpretation, and inversion. We advance new unified formulas for fast interpolation, differentiation, and integration and propose flexible high-precision algorithms to perform 3D and 2D potential-field- and gradient component transformations and derivative computations in the space domain using cubic B-splines. The spline-based algorithms are applicable to uniform or nonuniform rectangular grids for the 3D case and to regular or irregular grids for the 2D case. The fast Fourier transform (FFT) techniques require uniform grid spacing. The spline-based horizontal-derivative computations can be done at any point in the computational domain, whereas the FFT methods use only grid points. Comparisons between spline and FFT techniques through two gravity-gradient examples and one magnetic example show that results computed with the spline technique agree better with the exact theoretical data than do results computed with the FFT technique.
46
Cho, Yongchae, and Richard L. Gibson, Jr. "Reverse time migration via frequency-adaptive multiscale spatial grids." GEOPHYSICS 84, no. 2 (March 1, 2019): S41—S55. http://dx.doi.org/10.1190/geo2018-0292.1.
Full textAbstract:
Reverse time migration (RTM) is widely used because of its ability to recover complex geologic structures. However, RTM also has a drawback in that it requires significant computational cost. In RTM, wave modeling accounts for the largest part of the computing cost for calculating forward- and backward-propagated wavefields before applying an imaging condition. For this reason, we have applied a frequency-adaptive multiscale spatial grid to enhance the efficiency of the wave simulations. To implement wave modeling for different values of the spatial grid interval, we apply a model reduction technique, the generalized multiscale finite-element method (GMsFEM), which solves local spectral problems on a fine grid to simulate wave propagation on a coarser grid. We can enhance the speed of computation without sacrificing accuracy by using coarser grids for lower frequency waves, while applying a finer grid for higher frequency waves. In the proposed method, we can control the size of the coarse grid and level of heterogeneity of the wave solutions to tune the trade-off between speedup and accuracy. As we increase the expected level of complexity of the wave solutions, the GMsFEM wave modeling can capture more detailed features of waves. After computing the forward and backward wavefield on the coarse grid, we reproject the coarse wave solutions to the fine grid to construct the RTM gradient image. Although wave solutions are computed on a coarse grid, we still obtain the RTM images without reducing the image resolution by projecting coarse wave solutions to the fine grid. We determine the efficiency of the proposed imaging method using the Marmousi-2 model. We compare the RTM images using GMsFEM with a fixed coarse mesh and a multiple frequency-adaptive coarse meshes to indicate the image quality and computational speed of the new approach.
47
Barbato, Alessio, Clara Iacovano, and Francesco Cicci. "Impact of Grid Density on the Analysis of the In-Cylinder Flow of an Optical Engine." E3S Web of Conferences 197 (2020): 06018. http://dx.doi.org/10.1051/e3sconf/202019706018.
Full textAbstract:
The evaluation of Internal Combustion Engine (ICE) flows by 3D-CFD strongly depends on a combination of mutually interacting factors, among which grid resolution, closure model, numerics. A careful choice should be made in order to limit the extremely high computational cost and numerical problems arising from the combination of refined grids, high-order numeric schemes and complex geometries typical of ICEs. The paper focuses on the comparison between different grid strategies: in particular, attention is focused firstly on near-wall grid through the comparison between multi-layer and single-layer grids, and secondly on core grid density. The performance of each grid strategy is assessed in terms of accuracy and computational efficiency. A detailed comparison is presented against PIV flow measurements of the Spray Guided Darmstadt Engine available at the Darmstadt University of Technology. As many research groups are simultaneously working on the Darmstadt engine using different CFD codes and meshing approaches, it constitutes a perfect environment for both method validation and scientific cooperation. A motored engine condition is chosen and the flow evolution throughout the engine cycle is evaluated on two different section planes. Pros and cons of each grid strategy are highlighted and motivated.
48
GEIJER, JOHAN, BORIS LENHARD, ROXANA MERINO-MARTINEZ, GUNNAR NORSTEDT, and AMILCAR FLORES-MORALES. "GRID COMPUTING FOR THE ANALYSIS OF REGULATORY ELEMENTS IN CO-REGULATED SETS OF GENES." Parallel Processing Letters 14, no. 02 (June 2004): 137–50. http://dx.doi.org/10.1142/s0129626404001799.
Full textAbstract:
We describe an initial implementation of a platform for the analysis of gene promoter architecture for sets of genes from human and other higher organisms, using NorduGrid as the Grid Virtual Organization. The procedure leading from a set of co-regulated genes to a set of inferred common regulatory elements involves a number of computationally intensive, but well scalable steps. We show it is feasible to implement a high performance genomic regulatory sequence analysis pipeline on the Grid with minimal modification to the existing computational biology software components. We applied a job binning step to dramatically reduce the overhead for submitting a set of many small jobs to the Grid. Even with simple jobs and a relatively small size of the Grid, we observed up to 25-fold performance improvement over a comparable or more powerful single or dual-CPU platform. Our implementation of biological sequence alignment and transcription factor binding site algorithms on the Grid proves that even simple applications can take advantage of computational resources that adopted this computational paradigm.
49
Matsuoka, S., S. Shinjo, M. Aoyagi, S. Sekiguchi, H. Usami, and K. Miura. "Japanese Computational Grid Research Project: NAREGI." Proceedings of the IEEE 93, no. 3 (March 2005): 522–33. http://dx.doi.org/10.1109/jproc.2004.842748.
Full text
50
NEERAJ, RATHORE. "INSTALLATION OF ALCHEMI.NET IN COMPUTATIONAL GRID." i-manager's Journal on Computer Science 4, no. 2 (2016): 1. http://dx.doi.org/10.26634/jcom.4.2.8119.
Full text