Journal articles: 'Computational grids (Computer systems)'

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Jie, Wei, Tianyi Zang, Terence Hung, Stephen J. Turner, and Wentong Cai. "Information Management for Computational Grids." International Journal of Web Services Research 2, no. 3 (July 2005): 69–82. http://dx.doi.org/10.4018/jwsr.2005070103.

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Morozov, Alexander Yu, and Dmitry L. Reviznikov. "Adaptive Sparse Grids with Nonlinear Basis in Interval Problems for Dynamical Systems." Computation 11, no. 8 (August 1, 2023): 149. http://dx.doi.org/10.3390/computation11080149.

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Problems with interval uncertainties arise in many applied fields. The authors have earlier developed, tested, and proved an adaptive interpolation algorithm for solving this class of problems. The algorithm’s idea consists of constructing a piecewise polynomial function that interpolates the dependence of the problem solution on point values of interval parameters. The classical version of the algorithm uses polynomial full grid interpolation and, with a large number of uncertainties, the algorithm becomes difficult to apply due to the exponential growth of computational costs. Sparse grid interpolation requires significantly less computational resources than interpolation on full grids, so their use seems promising. A representative number of examples have previously confirmed the effectiveness of using adaptive sparse grids with a linear basis in the adaptive interpolation algorithm. The purpose of this paper is to apply adaptive sparse grids with a nonlinear basis for modeling dynamic systems with interval parameters. The corresponding interpolation polynomials on the quadratic basis and the fourth-degree basis are constructed. The efficiency, performance, and robustness of the proposed approach are demonstrated on a representative set of problems.

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PREVE, NIKOLAOS P., and EMMANUEL N. PROTONOTARIOS. "MONTE CARLO SIMULATION ON COMPUTATIONAL FINANCE FOR GRID COMPUTING." International Journal of Modeling, Simulation, and Scientific Computing 03, no. 03 (May 17, 2012): 1250010. http://dx.doi.org/10.1142/s1793962312500109.

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Monte Carlo methods are a class of computational algorithms that rely on repeated random sampling to compute their results. Monte Carlo methods are often used in simulating complex systems. Because of their reliance on repeated computation of random or pseudo-random numbers, these methods are most suited to calculation by a computer and tend to be used when it is infeasible or impossible to compute an exact result with a deterministic algorithm. In finance, Monte Carlo simulation method is used to calculate the value of companies, to evaluate economic investments and financial derivatives. On the other hand, Grid Computing applies heterogeneous computer resources of many geographically disperse computers in a network in order to solve a single problem that requires a great number of computer processing cycles or access to large amounts of data. In this paper, we have developed a simulation based on Monte Carlo method which is applied on grid computing in order to predict through complex calculations the future trends in stock prices.

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ARNOLD, DORIAN C., SATHISH S. VAHDIYAR, and JACK J. DONGARRA. "ON THE CONVERGENCE OF COMPUTATIONAL AND DATA GRIDS." Parallel Processing Letters 11, no. 02n03 (June 2001): 187–202. http://dx.doi.org/10.1142/s012962640100052x.

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Great advances in high-performance computing have given rise to scientific applications that place large demands on software and hardware infrastructures for both computational and data services. With these trends the necessity has emerged for distributed systems developers that once distinguished between these elements to acknowledge that indeed computational and data services are tightly coupled and need to be addressed simultaneously. In this article, we compile and discuss several strategies and techniques, like co-scheduling and co-allocation of computational and data services, dynamic storage capabilities, and quality-of-service, that can be used to help resolve some of the aforementioned issues. We present our interactions with a distributed computing system, NetSolve, and a Distributed Storage Infrastructure, IBP, as a case study of how some of these techniques can be effectively deployed and offer experimental evidence from early prototypes that validate our motivation and direction.

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Morozov, Alexander Yu, Andrey A. Zhuravlev, and Dmitry L. Reviznikov. "Sparse Grid Adaptive Interpolation in Problems of Modeling Dynamic Systems with Interval Parameters." Mathematics 9, no. 4 (February 3, 2021): 298. http://dx.doi.org/10.3390/math9040298.

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The paper is concerned with the issues of modeling dynamic systems with interval parameters. In previous works, the authors proposed an adaptive interpolation algorithm for solving interval problems; the essence of the algorithm is the dynamic construction of a piecewise polynomial function that interpolates the solution of the problem with a given accuracy. The main problem of applying the algorithm is related to the curse of dimension, i.e., exponential complexity relative to the number of interval uncertainties in parameters. The main objective of this work is to apply the previously proposed adaptive interpolation algorithm to dynamic systems with a large number of interval parameters. In order to reduce the computational complexity of the algorithm, the authors propose using adaptive sparse grids. This article introduces a novelty approach of applying sparse grids to problems with interval uncertainties. The efficiency of the proposed approach has been demonstrated on representative interval problems of nonlinear dynamics and computational materials science.

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Huang, Sili, Eric Aubanel, and Virendrakumar C. Bhavsar. "PaGrid: A Mesh Partitioner for Computational Grids." Journal of Grid Computing 4, no. 1 (February 1, 2006): 71–88. http://dx.doi.org/10.1007/s10723-005-9018-0.

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Jakóbik (Krok), Agnieszka, Daniel Grzonka, Joanna Kołodziej, Adriana E. Chis, and Horacio Gonzalez- ´Velez. "Energy Efficient Scheduling Methods for Computational Grids and Clouds." Journal of Telecommunications and Information Technology, no. 1 (March 30, 2017): 56–64. http://dx.doi.org/10.26636/jtit.2017.1.651.

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This paper presents an overview of techniques developed to improve energy efficiency of grid and cloud computing. Power consumption models and energy usage proles are presented together with energy efficiency measuring methods. Modeling of computing dynamics is discussed from the viewpoint of system identication theory, indicating basic experiment design problems and challenges. Novel approaches to cluster and network-wide energy usage optimization are surveyed, including multi-level power and software control systems, energy-aware task scheduling, resource allocation algorithms and frameworks for backbone networks management. Software-development techniques and tools are also presented as a new promising way to reduce power consumption at the computing node level. Finally, energy-aware control mechanisms are presented. In addition, this paper introduces the example of batch scheduler based on ETC matrix approach.

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Wei, Guiyi, Yun Ling, Athanasios V. Vasilakos, Bin Xiao, and Yao Zheng. "PIVOT: An adaptive information discovery framework for computational grids." Information Sciences 180, no. 23 (December 2010): 4543–56. http://dx.doi.org/10.1016/j.ins.2010.07.022.

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Chmaj, Grzegorz, Krzysztof Walkowiak, Michał Tarnawski, and Michał Kucharzak. "Heuristic algorithms for optimization of task allocation and result distribution in peer-to-peer computing systems." International Journal of Applied Mathematics and Computer Science 22, no. 3 (September 1, 2012): 733–48. http://dx.doi.org/10.2478/v10006-012-0055-0.

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Abstract Recently, distributed computing system have been gaining much attention due to a growing demand for various kinds of effective computations in both industry and academia. In this paper, we focus on Peer-to-Peer (P2P) computing systems, also called public-resource computing systems or global computing systems. P2P computing systems, contrary to grids, use personal computers and other relatively simple electronic equipment (e.g., the PlayStation console) to process sophisticated computational projects. A significant example of the P2P computing idea is the BOINC (Berkeley Open Infrastructure for Network Computing) project. To improve the performance of the computing system, we propose to use the P2P approach to distribute results of computational projects, i.e., results are transmitted in the system like in P2P file sharing systems (e.g., BitTorrent). In this work, we concentrate on offline optimization of the P2P computing system including two elements: scheduling of computations and data distribution. The objective is to minimize the system OPEX cost related to data processing and data transmission. We formulate an Integer Linear Problem (ILP) to model the system and apply this formulation to obtain optimal results using the CPLEX solver. Next, we propose two heuristic algorithms that provide results very

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José da Silva, Diego, Edmarcio Antonio Belati, and Eduardo Werley Silva dos Angelos. "FPAES: A Hybrid Approach for the Optimal Placement and Sizing of Reactive Compensation in Distribution Grids." Energies 13, no. 23 (December 4, 2020): 6409. http://dx.doi.org/10.3390/en13236409.

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Reactive power compensation with Capacitor Banks (CBs) is one of the most successful approaches used in distribution systems, mainly due to their versatility, long-term acceptance in the power industry, and reduced costs. Most allocation methods, however, lack specific strategies to handle the limited discrete nature of CBs sizes seeking to improve the overall optimization and computational performance. We present an algorithm for the Optimal Placement of Capacitor Banks (OPCB) in distribution systems by means of a hybrid Flower Pollination Algorithm (FPA)–Exhaustive Search (ES) approach. The pollination process itself determines the sets of buses for placement, while CBs sizes and the final fitness values of each pollen are selected after a full-search is conducted in the sizing space. As the sizing phase works on the limited search space of predetermined discrete bank values, the computational effort to find the optimum CB capacity is greatly reduced. Tests were performed on distribution systems of 10, 34, and 85 buses with respect to the objective function, final losses, and voltage profile. The algorithm offers an excellent compromise between solution quality and computational effort, when compared to similar approaches.

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Röhlig, Martin, Ruby Kala Prakasam, Jörg Stüwe, Christoph Schmidt, Oliver Stachs, and Heidrun Schumann. "Enhanced Grid-Based Visual Analysis of Retinal Layer Thickness with Optical Coherence Tomography." Information 10, no. 9 (August 23, 2019): 266. http://dx.doi.org/10.3390/info10090266.

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Optical coherence tomography enables high-resolution 3D imaging of retinal layers in the human eye. The thickness of the layers is commonly assessed to understand a variety of retinal and systemic disorders. Yet, the thickness data are complex and currently need to be considerably reduced prior to further processing and analysis. This leads to a loss of information on localized variations in thickness, which is important for early detection of certain retinal diseases. We propose an enhanced grid-based reduction and exploration of retinal thickness data. Alternative grids are computed, their representation quality is rated, and best fitting grids for given thickness data are suggested. Selected grids are then visualized, adapted, and compared at different levels of granularity. A visual analysis tool bundles all computational, visual, and interactive means in a flexible user interface. We demonstrate the utility of our tool in a complementary analysis procedure, which eases the evaluation of ophthalmic study data. Ophthalmologists successfully applied our solution to study localized variations in thickness of retinal layers in patients with diabetes mellitus.

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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.

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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.

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Ganzha, Victor G., and Evgenii V. Vorozhtsov. "Application of Computer Algebra Systems for Stability Analysis of Difference Schemes on Curvilinear Grids." Journal of Symbolic Computation 28, no. 3 (September 1999): 401–33. http://dx.doi.org/10.1006/jsco.1999.0289.

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Collignon, Tijmen, and Martin Van Gijzen. "Two implementations of the preconditioned conjugate gradient method on heterogeneous computing grids." International Journal of Applied Mathematics and Computer Science 20, no. 1 (March 1, 2010): 109–21. http://dx.doi.org/10.2478/v10006-010-0008-4.

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Two implementations of the preconditioned conjugate gradient method on heterogeneous computing gridsEfficient iterative solution of large linear systems on grid computers is a complex problem. The induced heterogeneity and volatile nature of the aggregated computational resources present numerous algorithmic challenges. This paper describes a case study regarding iterative solution of large sparse linear systems on grid computers within the software constraints of the grid middleware GridSolve and within the algorithmic constraints of preconditioned Conjugate Gradient (CG) type methods. We identify the various bottlenecks induced by the middleware and the iterative algorithm. We consider the standard CG algorithm of Hestenes and Stiefel, and as an alternative the Chronopoulos/Gear variant, a formulation that is potentially better suited for grid computing since it requires only one synchronisation point per iteration, instead of two for standard CG. In addition, we improve the computation-to-communication ratio by maximising the work in the preconditioner. In addition to these algorithmic improvements, we also try to minimise the communication overhead within the communication model currently used by the GridSolve middleware. We present numerical experiments on 3D bubbly flow problems using heterogeneous computing hardware that show lower computing times and better speed-up for the Chronopoulos/Gear variant of conjugate gradients. Finally, we suggest extensions to both the iterative algorithm and the middleware for improving granularity.

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Darwish, M., H. Diab, and F. Moukalled. "An Educational Two-Dimensional Interactive Dynamic Grid Generator." International Journal of Mechanical Engineering Education 24, no. 4 (October 1996): 279–90. http://dx.doi.org/10.1177/030641909602400406.

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This paper describes IDGG, an Interactive Dynamic Grid Generator, for use as an educational tool by students studying computational fluid dynamics. The package is a Windows applications and runs on IBM PC, or compatible, computers. It is written in Pascal and built using object-oriented programming. The computer program allows the user to generate boundary-fitted curvilinear grids in any two-dimensional domain. The procedure adopted requires the user to perform the transformation step by step allowing him/her to easily grasp the concept of boundary-fitted coordinate systems. In addition, IDGG may be used by CFD researchers to display results graphically in the form of vector fields, contours, and two- and three-dimensional plots. The examples provided show the effectiveness of the package as a teaching aid.

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Ma, Tianlong, Lin Zhang, Fujun Cao, and Yongbin Ge. "A Special Multigrid Strategy on Non-Uniform Grids for Solving 3D Convection–Diffusion Problems with Boundary/Interior Layers." Symmetry 13, no. 7 (June 24, 2021): 1123. http://dx.doi.org/10.3390/sym13071123.

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Boundary or interior layer problems of high-dimensional convection–diffusion equations have distinct asymmetry. Consequently, computational grid distributions and linear algebraic systems arising from finite difference schemes for them are also asymmetric. Numerical solutions for these kinds of problems are more complicated than those symmetric problems. In this paper, we extended our previous work on the partial semi-coarsening multigrid method combined with the high-order compact (HOC) difference scheme for solving the two-dimensional (2D) convection–diffusion problems on non-uniform grids to the three-dimensional (3D) cases. The main merit of the present method is that the multigrid method on non-uniform grids can be performed with a different number of grids in different coordinate axes, which is more efficient than the multigrid method on non-uniform grids with the same number of grids in different coordinate axes. Numerical experiments are carried out to validate the accuracy and efficiency of the present method. It is shown that, without losing the high precision, the present method is very effective to reduce computing cost by cutting down the number of grids in the direction(s) which does/do not contain boundary or interior layer(s).

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Wang, Lizhe, Dan Chen, Ze Deng, and Fang Huang. "Large scale distributed visualization on computational Grids: A review." Computers & Electrical Engineering 37, no. 4 (July 2011): 403–16. http://dx.doi.org/10.1016/j.compeleceng.2011.05.010.

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Tafani, Daniele, Burak Kantarci, Hussein T. Mouftah, Conor McArdle, and Liam P. Barry. "A distributed framework for energy-efficient lightpaths in computational grids." Journal of High Speed Networks 19, no. 1 (2013): 1–18. http://dx.doi.org/10.3233/jhs-130457.

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Chen, Uei-Ren, and Woei Lin. "Aligning block permutation methods for topology transformation on computational grids." Journal of Supercomputing 61, no. 3 (April 21, 2011): 545–59. http://dx.doi.org/10.1007/s11227-011-0613-5.

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Aziz, Abdul, and Hesham El-Rewini. "Power efficient scheduling heuristics for energy conservation in computational grids." Journal of Supercomputing 57, no. 1 (February 3, 2011): 65–80. http://dx.doi.org/10.1007/s11227-011-0559-7.

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Zeng, Fancheng, Guanqiu Qi, Zhiqin Zhu, Jian Sun, Gang Hu, and Matthew Haner. "Convex Neural Networks Based Reinforcement Learning for Load Frequency Control under Denial of Service Attacks." Algorithms 15, no. 2 (January 23, 2022): 34. http://dx.doi.org/10.3390/a15020034.

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With the increase in the complexity and informatization of power grids, new challenges, such as access to a large number of distributed energy sources and cyber attacks on power grid control systems, are brought to load-frequency control. As load-frequency control methods, both aggregated distributed energy sources (ADES) and artificial intelligence techniques provide flexible solution strategies to mitigate the frequency deviation of power grids. This paper proposes a load-frequency control strategy of ADES-based reinforcement learning under the consideration of reducing the impact of denial of service (DoS) attacks. Reinforcement learning is used to evaluate the pros and cons of the proposed frequency control strategy. The entire evaluation process is realized by the approximation of convex neural networks. Convex neural networks are used to convert the nonlinear optimization problems of reinforcement learning for long-term performance into the corresponding convex optimization problems. Thus, the local optimum is avoided, the optimization process of the strategy utility function is accelerated, and the response ability of controllers is improved. The stability of power grids and the convergence of convex neural networks under the proposed frequency control strategy are studied by constructing Lyapunov functions to obtain the sufficient conditions for the steady states of ADES and the weight convergence of actor–critic networks. The article uses the IEEE14, IEEE57, and IEEE118 bus testing systems to verify the proposed strategy. Our experimental results confirm that the proposed frequency control strategy can effectively reduce the frequency deviation of power grids under DoS attacks.

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Gumen, Olena, Ganna Smakovska, and Yuriy Maksуmenko. "THE USE OF NESTED ADAPTIVE GRIDS FOR MODELING HEAT TRANSFER PROCESSES IN INFORMATION AND CONTROL SYSTEMS OF COMPLEX EQUIPMENT SAMPLES." Collection of scientific works of Odesa Military Academy, no. 16 (February 11, 2022): 59–65. http://dx.doi.org/10.37129/2313-7509.2021.16.59-65.

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Modeling of processes on the use of adaptive grids for information and control systems of complex samples of equipment is offered. Application in the simulation of various natural phenomena and processes have obtained differential equations with partial derivatives. The principle of replacing the continuous domain of the unknown function by a discrete set of points (grid) is the basis of numerical methods for solving such equations. The complex solution of such problems is a definite scientific problem, the solution of which determines the accuracy of the numerical solution in areas where the gradient of the desired function reaches large values, significantly affects the accuracy of the solution throughout the region. The study considers the method of constructing nested adaptive difference grids for modeling heat transfer processes in information-control systems of complex samples of equipment, which are condensed in zones of rapid change of the desired function to solve two-dimensional nonstationary equation of thermal conductivity. Existing methods of constructing non-uniform grids before calculations, based on finding possible zones of high gradients are not effective in non-stationary problems, where these zones can change their position over time. The proposed algorithm for finding zones with significant gradients of the desired function in the process of the task analyzes the behavior of the function, controls the error and builds a time variable and a non-uniform difference grid. This significantly reduces the machine time required to solve problems with significant gradients in some areas of the computational domain. The solution of the problem for the main and nested grids can be performed in parallel, which will further reduce the time to solve when using multi-core systems. Keywords: computer model, finite difference method, difference mesh, nested mesh, modeling of heat transfer processes, information and control systems.

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Pierce, Marlon E. "Special Issue Editorial Introduction: Grids and Geospatial Information Systems." Concurrency and Computation: Practice and Experience 20, no. 14 (September 25, 2008): 1611–15. http://dx.doi.org/10.1002/cpe.1381.

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Mo, Tiexiang, and Guodong Li. "Parallel Accelerated Fifth-Order WENO Scheme-Based Pipeline Transient Flow Solution Model." Applied Sciences 12, no. 14 (July 21, 2022): 7350. http://dx.doi.org/10.3390/app12147350.

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The water hammer phenomenon is the main problem in long-distance pipeline networks. The MOC (Method of characteristics) and finite difference methods lead to severe constraints on the mesh and Courant number, while the finite volume method of the second-order Godunov scheme has limited intermittent capture capability. These methods will produce severe numerical dissipation, affecting the computational efficiency at low Courant numbers. Based on the lax-Friedrichs flux splitting method, combined with the upstream and downstream virtual grid boundary conditions, this paper uses the high-precision fifth-order WENO scheme to reconstruct the interface flux and establishes a finite volume numerical model for solving the transient flow in the pipeline. The model adopts the GPU parallel acceleration technology to improve the program’s computational efficiency. The results show that the model maintains the excellent performance of intermittent excitation capture without spurious oscillations even at a low Courant number. Simultaneously, the model has a high degree of flexibility in meshing due to the high insensitivity to the Courant number. The number of grids in the model can be significantly reduced and higher computational efficiency can be obtained compared with MOC and the second-order Godunov scheme. Furthermore, this paper analyzes the acceleration effect in different grids. Accordingly, the acceleration effect of the GPU technique increases significantly with the increase in the number of computational grids. This model can support efficient and accurate fast simulation and prediction of non-constant transient processes in long-distance water pipeline systems.

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Deese, Anthony S., and Chika O. Nwankpa. "Utilization of FPAA Technology for Emulation of Multiscale Power System Dynamics in Smart Grids." IEEE Transactions on Smart Grid 2, no. 2 (December 2011): 606–14. http://dx.doi.org/10.1109/tsg.2011.2161782.

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In this paper, the authors address computational issues associated with implementation of VLSI technologies-specifically, the utilization of field programmable analog array (FPAA) technology to analyze the steady-state as well dynamic behavior of nonlinear, multiscale power systems. Emphasis is placed on the following issues: adaptation of FPAA hardware for power flow analyses, design and construction of physical prototype, optimal hardware scaling, and application of emulation to transient fault analyses.

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Yu, Kachan, and Kuznetsov V. "About technical and economic indicators of wind and photoelectric stations use in the systems of network consumer railway supply systems." Theory and practice of metallurgy, no. 6 (September 21, 2019): 68–74. http://dx.doi.org/10.34185/tpm.5.2019.09.

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Purpose. To analyze the technical and economic indicators of the use of wind and photovoltaic stations in the power supply systems of non-traction consumers of railway power grids. The research methodology is based on modern methods of computational mathematics, statistics and information analysis using modern computer technology. Findings. The authors analyze the current prerequisites for the use of electricity generated from renewable sources (wind and photovoltaic stations) to supply non-traction consumers of railway power grids. The authors note that for reliable power supply to non-traction consumers in the presence of accidental wind flow or intensity of solar radiation, the capacity of wind and photovoltaic plants will need to be significantly overestimated, which leads to a significant increase in capital costs for construction. The paper presents examples of implementation of options for the construction of the above wind and photovoltaic stations for the variable nature of wind speed and intensity of solar radiation for specific regions of Ukraine (Vasylivka, Zaporizhia region). The authors present variants of the basic schemes of wind, solar and combined electric power supply systems for non-traction consumers. Information on technical and economic indicators of the most common domestic photo modules and wind turbines on the Ukrainian market is provided. The originality of the work is reflected in the examples of the introduction of options for the construction of wind and photovoltaic stations for the variable nature of wind speed and intensity of solar radiation for specific regions of Ukraine. Practical implications. The above calculation of the cost of the required number of power sources at wind, solar and combined power plants helps to choose the least expensive option for the introduction of renewable energy sources for non-traction consumers of railway networks. Keywords: renewable energy sources, photovoltaic installation, railway power supply networks, non-traction consumers of railway power grids, electricity production, solar radiation intensity, wind flow rate, capital expenditures.

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Nurkanović, Armin, Amer Mešanović, Mario Sperl, Sebastian Albrecht, Ulrich Münz, Rolf Findeisen, and Moritz Diehl. "Optimization-based primary and secondary control of microgrids." at - Automatisierungstechnik 68, no. 12 (November 18, 2020): 1044–58. http://dx.doi.org/10.1515/auto-2020-0088.

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AbstractThis article discusses how to use optimization-based methods to efficiently operate microgrids with a large share of renewables. We discuss how to apply a frequency-based method to tune the droop parameters in order to stabilize the grid and improve oscillation damping after disturbances. Moreover, we propose a centralized real-time feasible nonlinear model predictive control (NMPC) scheme to achieve efficient frequency and voltage control while considering economic dispatch results. Centralized NMPC for secondary control is a computationaly challenging task. We demonstrate how to reduce the computational burden using the Advanced Step Real-Time Iteration with nonuniform discretization grids. This reduces the computational burden up to 60 % compared to a standard uniform approach, while having only a minor performance loss. All methods are validated on the example of a 9-bus microgrid, which is modeled with a complex differential algebraic equation.

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Skotniczny, Marcin, Maciej Paszyński, and Anna Paszyńska. "Bisection weighted by element size ordering algorithm for multi-frontal solver executed over 3D h refined grids." Computer Methods in Material Science 16, no. 1 (2016): 54–61. http://dx.doi.org/10.7494/cmms.2016.1.0560.

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In this paper we present an algorithm for generation of ordering over 3D grids h refined towards singularities. The ordering controls the execution of multi-frontal direct solver algorithm on systems of linear equations generated by 3D h adaptive finite element method. Our algorithm uses additional knowledge about the structure of the computational mesh, not available to alternative ordering algorithms. The proposed ordering algorithm outperforms other state-of-the-art orderings available through MUMPS interface, namely nested-dissections, AMD and PORD.

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Kibets, A. I., and Yu A. Kalinina. "REVIEW OF LITERATURE ON PARALLELING FINITE ELEMENT SCHEMES FOR SOLVING NONLINEAR STRUCTURE DEFORMATION PROBLEMS ON SUPER COMPUTERS." Problems of Strength and Plasticity 84, no. 4 (2023): 522–38. http://dx.doi.org/10.32326/1814-9146-2023-85-4-522-538.

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This article provides a review of publications devoted to the features of using parallel computing systems for solving problems in continuum mechanics using the finite element method. These publications discuss the conditions for the successful application of algorithms and software developed for the efficient operation of parallel computing systems. Methods for accelerating the solution of a problem by taking into account its specifics are studied and estimates of their effectiveness are given. The issues of application are considered: iterative methods with preconditioning for solving sparse systems of linear algebraic equations with an irregular structure, both symmetric and asymmetric; finite element approximations on unstructured and quasi-structured computational grids; pipelineization of the computational process during spatial decomposition of the computational domain; a parallel computing method with an explicit and implicit time integration scheme for large-scale problems in the mechanics of structures and solids; finite element modeling of contact-impact problems using a graphics processor; matrix-free approach to finite element calculations intended for graphic processors; an explicit method of asynchronous step-by-step parallel calculations to reduce computation time when refining the mesh in a certain local area; discrete and finite element method and graphic processor for solid particle interaction modeling, including contact detection, force calculation and information updating; methods for parallelizing cyclic sections of sequential programs, based on determining the possibility of parallel execution of loop iterations, searching and parallelizing linear sections within loops with an unknown number of iterations.

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Li, Xiaodong, and Zheng Xu. "Enhanced Efficient EMT-Type Model of the MMCs Based on Arm Equivalence." Applied Sciences 10, no. 23 (November 26, 2020): 8421. http://dx.doi.org/10.3390/app10238421.

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The large number of switching elements in modular multilevel converters (MMCs) contribute a tremendous computational burden for electromagnetic transient (EMT) simulation programs. Detailed equivalent models (DEMs) and average value model (AVMs) are currently two major types of accurate and efficient model. However, the DEMs are still computationally inefficient for the simulation scenarios in large-scale MMC based high-voltage direct current (MMC-HVDC) grids, as the models represent all submodule (SMs) switching events, and memorize all individual capacitor voltages. Though the AVMs provide a faster simulation speed by using a single equivalent capacitor on the DC side, they have a relatively low simulation accuracy compared to DEMs, especially under blocked mode. This paper proposes an enhanced computationally efficient model based on arm equivalence (AEM), which can accurately represent the dynamic behaviors in both de-blocked and blocked modes. Compared to the DEMs, the proposed AEM is more efficient, with no loss of accuracy, and the simulation speed is irrespective of the SM number. The accuracy and computational efficiency of the proposed model were validated against the DEM and AVM through several simulation scenarios in a two-terminal MMC-HVDC system on the power systems computer aided design/ electromagnetic transient in DC system (PSCAD/EMTDC) program.

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Nikitina, Alla, Alyona Filinа, Vladimir Litvinov, and Asya Atayan. "Development of a specialized software complex for modeling the biogeochemical cycles in the Azov sea, including calculation modules of transformation of phosphorus, nitrogen, silicon, sulfur and dissolved oxygen forms, as well as the dynamics of phyto-and zooplatonkton." E3S Web of Conferences 363 (2022): 02023. http://dx.doi.org/10.1051/e3sconf/202236302023.

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The paper is devoted to the development of a software complex for predictive modeling of biogeochemical cycles in the Azov Sea on high-performance computer systems in a limited time. The complex development includes the creation of software modules of the computational structure to calculate the concentrations of phosphorus, nitrogen, silicon, sulfur, dissolved oxygen forms and describe in detail phyto- and zooplankton dynamics in the Azov Sea; the integration of various environmental databases, satellite monitoring. The complex is adapted to solve a wide class of predictive problems of water ecology and water resources management. It includes the implementation of developed 3D mathematical model of hydrophysics and biological kinetics on computational grids, consistent with the complex shape of the water coastline. Parallel algorithms have been developed for numerical implementation of water ecology problems, oriented to high-performance computer systems. To increase the calculation efficiency of computational grid fragments assigned to graphics accelerators, an algorithm and its software implementation were developed in the CUDA C language. Based on the developed specialized software tools focused on supercomputers, scenarios for the development of the environmental situation and sustainable development management at biological rehabilitation of the Azov Sea were developed, including forecasts of changes in harmful algae concentration; dynamics of spatial interaction processes between phyto- and zooplankton populations; evolution of biological kinetics processes on the example of plankton interaction.

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Karakus, Ali, Tim Warburton, Mehmet Haluk Aksel, and Cuneyt Sert. "An adaptive fully discontinuous Galerkin level set method for incompressible multiphase flows." International Journal of Numerical Methods for Heat & Fluid Flow 28, no. 6 (June 4, 2018): 1256–78. http://dx.doi.org/10.1108/hff-03-2017-0098.

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Purpose This study aims to focus on the development of a high-order discontinuous Galerkin method for the solution of unsteady, incompressible, multiphase flows with level set interface formulation. Design/methodology/approach Nodal discontinuous Galerkin discretization is used for incompressible Navier–Stokes, level set advection and reinitialization equations on adaptive unstructured elements. Implicit systems arising from the semi-explicit time discretization of the flow equations are solved with a p-multigrid preconditioned conjugate gradient method, which minimizes the memory requirements and increases overall run-time performance. Computations are localized mostly near the interface location to reduce computational cost without sacrificing the accuracy. Findings The proposed method allows to capture interface topology accurately in simulating wide range of flow regimes with high density/viscosity ratios and offers good mass conservation even in relatively coarse grids, while keeping the simplicity of the level set interface modeling. Efficiency, local high-order accuracy and mass conservation of the method are confirmed through distinct numerical test cases of sloshing, dam break and Rayleigh–Taylor instability. Originality/value A fully discontinuous Galerkin, high-order, adaptive method on unstructured grids is introduced where flow and interface equations are solved in discontinuous space.

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Jeong, Se-Min, and Chang-Yull Lee. "Weighted Moving Square-Based Solver for Unsteady Incompressible Laminar Flow Simulations." Applied Sciences 12, no. 7 (March 30, 2022): 3519. http://dx.doi.org/10.3390/app12073519.

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For computational fluid dynamics simulations, grid systems are generally used in the Eulerian frame for both structured and unstructured grids and solvers designed for the chosen grid systems. In contrast to the grid-based method, in which the connection information with neighboring grids must be maintained, gridless methods do not require an underlying connectivity in the form of control volumes or elements. Hence, gridless methods are feasible and robust for the problems with moving boundary and/or complicated boundary shapes. In this study, a Eulerian gridless solver is proposed, and its application for simulating two-dimensional unsteady viscous flows in low Reynolds number regions is investigated. The solver utilizes the weighted moving square method to obtain the spatial derivatives of the governing equations and solve the pressure Poisson equation iteratively. Simple remedies to satisfy the boundary conditions in the finite difference method are applied. The fractional step method with the second-order Adams–Bashforth method is used for time integration. Some benchmark problems were solved using the developed solver, and the results were compared with those of other experimental and computational methods. Good agreement with the results of other methods confirmed the validity of the proposed solver.

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De Sarkar, Ajanta, Sarbani Roy, Dibyajyoti Ghosh, Rupam Mukhopadhyay, and Nandini Mukherjee. "An Adaptive Execution Scheme for Achieving Guaranteed Performance in Computational Grids." Journal of Grid Computing 8, no. 1 (May 28, 2009): 109–31. http://dx.doi.org/10.1007/s10723-009-9120-9.

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BIEN, R., B. FUCHS, and R. WIELEN. "High Spatial Resolution Using the Conventional Particle-Mesh Technique." International Journal of Modern Physics C 02, no. 01 (March 1991): 3–13. http://dx.doi.org/10.1142/s0129183191000020.

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The use of the particle-mesh technique has a long and successful history in the field of computer simulations of collisionless gravitational systems, such as galaxies. Since the method allows the treatment of large numbers of particles statistical noise has only a small effect. On the other hand, severe problems arise when high density peaks must be resolved. In order to master these difficulties we have worked out a procedure which is an extension of the standard particle-mesh code in three-dimensional Cartesian coordinates. The basic idea is simply to introduce additional grids and sub-grids in regions with steep density gradients such that the system of grids is re-arranged at each integration step. In this way we are able to simulate single and interacting galaxies. In the present paper a short review of some frequently used methods of galaxy simulations is given and our own method is outlined.

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Shen, Zhanfeng, Jiancheng Luo, Chenghu Zhou, Guangyu Huang, Weifeng Ma, and Dongping Ming. "System design and implementation of digital-image processing using computational grids." Computers & Geosciences 31, no. 5 (June 2005): 619–30. http://dx.doi.org/10.1016/j.cageo.2004.11.014.

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Altameem, T., and M. Amoon. "An agent-based approach for dynamic adjustment of scheduled jobs in computational grids." Journal of Computer and Systems Sciences International 49, no. 5 (October 2010): 765–72. http://dx.doi.org/10.1134/s1064230710050114.

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Abu Sarhan, Mohammad, Andrzej Bien, and Szymon Barczentewicz. "Use of analytical hierarchy process for selecting and prioritizing islanding detection methods in power grids." International Journal of Electrical and Computer Engineering (IJECE) 14, no. 3 (June 1, 2024): 2422. http://dx.doi.org/10.11591/ijece.v14i3.pp2422-2435.

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One of the problems that are associated to power systems is islanding condition, which must be rapidly and properly detected to prevent any negative consequences on the system's protection, stability, and security. This paper offers a thorough overview of several islanding detection strategies, which are divided into two categories: classic approaches, including local and remote approaches, and modern techniques, including techniques based on signal processing and computational intelligence. Additionally, each approach is compared and assessed based on several factors, including implementation costs, non-detected zones, declining power quality, and response times using the analytical hierarchy process (AHP). The multi-criteria decision-making analysis shows that the overall weight of passive methods (24.7%), active methods (7.8%), hybrid methods (5.6%), remote methods (14.5%), signal processing-based methods (26.6%), and computational intelligent-based methods (20.8%) based on the comparison of all criteria together. Thus, it can be seen from the total weight that hybrid approaches are the least suitable to be chosen, while signal processing-based methods are the most appropriate islanding detection method to be selected and implemented in power system with respect to the aforementioned factors. Using Expert Choice software, the proposed hierarchy model is studied and examined.

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Anderson, Christopher R., Mark F. Gyure, Sam Quinn, Andrew Pan, Richard S. Ross, and Andrey A. Kiselev. "High-precision real-space simulation of electrostatically confined few-electron states." AIP Advances 12, no. 6 (June 1, 2022): 065123. http://dx.doi.org/10.1063/5.0089350.

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In this paper, we present a computational procedure that utilizes real-space grids to obtain high precision approximations of electrostatically confined few-electron states such as those that arise in gated semiconductor quantum dots. We use the full configuration interaction method with a continuously adapted orthonormal orbital basis to approximate the ground and excited states of such systems. We also introduce a benchmark problem based on a realistic analytical electrostatic potential for quantum dot devices. We show that our approach leads to highly precise computed energies and energy differences over a wide range of model parameters. The analytic definition of the benchmark allows for a collection of tests that are easily replicated, thus facilitating comparisons with other computational approaches.

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Sarhan, Amany, Ahmed I. Saleh, and Amr M. Hamed. "A reliable-adaptive scheduler for computational grids with failure recovery and rescheduling mechanisms." International Journal of Grid and Utility Computing 2, no. 1 (2011): 59. http://dx.doi.org/10.1504/ijguc.2011.039981.

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Venetis, Ioannis E., Vasso Saltogianni, Stathis Stiros, and Efstratios Gallopoulos. "Multivariable inversion using exhaustive grid search and high-performance GPU processing: a new perspective." Geophysical Journal International 221, no. 2 (January 23, 2020): 905–27. http://dx.doi.org/10.1093/gji/ggaa042.

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SUMMARY Exhaustive searches in regular grids is a traditional and effective method for inversion, that is numerical solution of systems of non-linear equations which cannot be solved using formal algebraic techniques. However, this technique is effective for very few (3–4) variables and is slow. Recently, the first limitation was to a major degree overpassed with the new TOPological INVersion (TOPINV) algorithm which was used for inversion of systems with up to 18, or even more unknown variables. The novelty of this algorithm is that it is not based on the principle of the mean minimum misfit (cost function) between observations and model predictions, used by most inversion techniques. The new algorithm investigates for each gridpoint whether misfits of each observation are within specified uncertainty intervals, and stores clusters of ‘successful’ gridpoints in matrix form. These clusters (ensembles, sets) of gridpoints are tested whether they satisfy certain criteria and are then used to compute one or more optimal statistical solutions. The new algorithm is efficient for highly non-linear problems with high measurement uncertainties (low signal-to-noise ratio, SNR) and poor distribution of observations, that is problems leading to complicated 3-D mean misfit surfaces without dominant peaks, but it is slow when running in common computers. To overcome this limitation, we used GPUs which permit parallel processing in common computers, but faced another computational problem: GPU parallel processing supports only up to three dimensions. To solve this problem, we used CUDA programming and optimized the distribution of the computational load to all GPU cores. This leads up to 100x speedup relative to common CPU processing, as is derived from comparative tests with synthetic data for two typical inversion geophysical problems with up to 18 unknown variables, Mogi magma source modeling and elastic dislocation modeling of seismic faults. This impressive speedup makes the GPU/CUDA implementation of TOPINV practical even for low-latency solution of certain geophysical problems. This speedup in calculations also permitted to investigate the performance of the new algorithm in relation to the density of the adopted grids. We focused on a typical problem of elastic dislocation in unfavorable conditions (poor observations geometry, data with low SNR) and on synthetic observations with noise, so that the difference of each solution from the ‘true’/reference value was known (accuracy-based approach). Application of the algorithm revealed stable, accurate and precise solutions, with quality increasing with the grid density. Solution defects (bias), mainly produced by very coarse grids, can be identified through specific diagnostic criteria, dictating finer search grids.

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Shah, Sayed Chhattan, and Myong Soon Park. "An Energy-Efficient Resource Allocation Scheme for Mobile Ad Hoc Computational Grids." Journal of Grid Computing 9, no. 3 (April 16, 2011): 303–23. http://dx.doi.org/10.1007/s10723-011-9188-x.

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Liang, Feng, Yunzhen Liu, Hai Liu, Shilong Ma, and Bettina Schnor. "A Parallel Job Execution Time Estimation Approach Based on User Submission Patterns within Computational Grids." International Journal of Parallel Programming 43, no. 3 (November 12, 2013): 440–54. http://dx.doi.org/10.1007/s10766-013-0294-1.

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Kołodziej, Joanna, and Fatos Xhafa. "Modern approaches to modeling user requirements on resource and task allocation in hierarchical computational grids." International Journal of Applied Mathematics and Computer Science 21, no. 2 (June 1, 2011): 243–57. http://dx.doi.org/10.2478/v10006-011-0018-x.

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Modern approaches to modeling user requirements on resource and task allocation in hierarchical computational grids Tasks scheduling and resource allocation are among crucial issues in any large scale distributed system, including Computational Grids (CGs). These issues are commonly investigated using traditional computational models and resolution methods that yield near-optimal scheduling strategies. One drawback of such approaches is that they cannot effectively tackle the complex nature of CGs. On the one hand, such systems account for many administrative domains with their own access policies, user privileges, etc. On the other, CGs have hierarchical nature and therefore any computational model should be able to effectively express the hierarchical architecture in the optimization model. Recently, researchers have been investigating the use of game theory for modeling user requirements regarding task and resource allocation in grid scheduling problems. In this paper we present two general non-cooperative game approaches, namely, the symmetric non-zero sum game and the asymmetric Stackelberg game for modeling grid user behavior defined as user requirements. In our game-theoretic approaches we are able to cast new requirements arising in allocation problems, such as asymmetric users relations, security and reliability restrictions in CGs. For solving the games, we designed and implemented GA-based hybrid schedulers for approximating the equilibrium points for both games. The proposed hybrid resolution methods are experimentally evaluated through the grid simulator under heterogeneity, and large-scale and dynamics conditions. The relative performance of the schedulers is measured in terms of the makespan and flowtime metrics. The experimental analysis showed high efficiency of meta-heuristics in solving the game-based models, especially in the case of an additional cost of secure task scheduling to be paid by the users.

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Gundy-Burlet, K. L., M. M. Rai, R. C. Stauter, and R. P. Dring. "Temporally and Spatially Resolved Flow in a Two-Stage Axial Compressor: Part 2—Computational Assessment." Journal of Turbomachinery 113, no. 2 (April 1, 1991): 227–32. http://dx.doi.org/10.1115/1.2929090.

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Fluid dynamics of turbomachines are complicated because of aerodynamic interactions between rotors and stators. It is necessary to understand the aerodynamics associated with these interactions in order to design turbomachines that are both light and compact as well as reliable and efficient. The current study uses an unsteady, thin-layer Navier–Stokes zonal approach to investigate the unsteady aerodynamics of a multistage compressor. Relative motion between rotors and stators is made possible by the use of systems of patched and overlaid grids. Results have been computed for a 2 1/2-stage compressor configuration. The numerical data compare well with experimental data for surface pressures and wakes. In addition, the effect of grid refinement on the solution is studied.

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Rahman, Ashiqur Md, and Rashedur M. Rahman. "CAPM Indexed Hybrid E-Negotiation for Resource Allocation in Grid Computing." International Journal of Grid and High Performance Computing 5, no. 2 (April 2013): 72–91. http://dx.doi.org/10.4018/jghpc.2013040105.

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Computational Grids are a promising platform for executing large-scale resource intensive applications. This paper identifies challenges in managing resources in a Grid computing environment and proposes computational economy as a metaphor for effective management of resources and application scheduling. It identifies distributed resource management challenges and requirements of economy-based Grid systems, and proposes an economy based negotiation system protocol for cooperative and competitive trading of resources. Dynamic pricing for services and good level of Pareto optimality make auctions more attractive for resource allocation over other economic models. In a complex Grid environment, the communication demand can become a bottleneck; that is, a number of messages need to be exchanged for matching suitable service providers and consumers. The Fuzzy Trust integrated hybrid Capital Asset Pricing Model (CAPM) shows the higher user centric satisfaction and provides the equilibrium relationship between the expected return and risk on investments. This paper also presents an analysis on the communication requirements and the necessity of the CAPMAuction in Grid environment.

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Savyanavar, Amit Sadanand, and Vijay Ram Ghorpade. "Application Checkpointing Technique for Self-Healing From Failures in Mobile Grid Computing." International Journal of Grid and High Performance Computing 11, no. 2 (April 2019): 50–62. http://dx.doi.org/10.4018/ijghpc.2019040103.

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A mobile grid (MG) consists of interconnected mobile devices which are used for high performance computing. Fault tolerance is an important property of mobile computational grid systems for achieving superior arrangement reliability and faster recovery from failures. Since the failure of the resources affects task execution fatally, fault tolerance service is essential to achieve QoS requirement in MG. The faults which occur in MG are link failure, node failure, task failure, limited bandwidth etc. Detecting these failures can help in better utilisation of the resources and timely notification to the user in a MG environment. These failures result in loss of computational results and data. Many algorithms or techniques were proposed for failure handling in traditional grids. The authors propose a checkpointing based failure handling technique which will improve arrangement reliability and failure recovery time for the MG network. Experimentation was conducted by creating a grid of ubiquitously available Android-based mobile phones.

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Ibrahim, Ahmad Asrul, Khairuddin Khalid, Hussain Shareef, and Nor Azwan Mohamed Kamari. "A Bounded Exhaustive Search Technique for Optimal Phasor Measurement Unit Placement in Power Grids." Symmetry 12, no. 12 (December 7, 2020): 2021. http://dx.doi.org/10.3390/sym12122021.

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This paper proposes a technique to determine the possible optimal placement of the phasor measurement unit (PMU) in power grids for normal operating conditions. All possible combinations of PMU placement, including infeasible combinations, are typically considered in finding the optimal solution, which could be a massive search space. An integer search algorithm called the bounded search technique is introduced to reduce the search space in solving a minimum number of PMU allocations whilst maintaining full system observability. The proposed technique is based on connectivity and symmetry constraints that can be derived from the observability matrix. As the technique is coupled with the exhaustive technique, the technique is called the bounded exhaustive search (BES) technique. Several IEEE test systems, namely, IEEE 9-bus, IEEE 14-bus, IEEE 24-bus and IEEE 30-bus, are considered to showcase the performance of the proposed technique. An initial Monte Carlo simulation was carried out to evaluate the capability of the bounded search technique in providing a smaller feasible search space. The effectiveness of the BES technique in terms of computational time is compared with the existing exhaustive technique. Results demonstrate that the search space can be reduced tremendously, and the computational burden can be eased, when finding the optimal PMU placement in power grids.

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Ambareen, Javeria, and Prabhakar M. "Secured Wireless Sensor Network Protocol using Rabin-assisted Multifactor Authentication." International Journal of Computer Network and Information Security 14, no. 4 (August 8, 2022): 60–74. http://dx.doi.org/10.5815/ijcnis.2022.04.05.

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Wireless sensor networks (WSNs) when combined with Internet-of-things (IoT) enable a wide range of applications across multiple domains. Sensor nodes in these wireless sensor networks like any other Internet-connected device are resource constrained and vulnerable to a variety of malicious attacks thereby compromising security. Consequently, a secure and efficient lightweight cryptographic protocol is required that can provide a balance between end-to-end security offering all features but yet lightweight. For secure data transmission and access, newer multi-factor authentication and key management features must be developed as majority of existing techniques have high computational overheads and are vulnerable to a wide range of attacks. In this paper, we propose a Rabin-assisted three-factor authentication protocol that uses the computational asymmetry of Rabin cryptosystem in addition to user password, smartcard and biometric for increased security. NS2 based simulation proves that the proposed protocol outperforms the baseline ad-hoc on-demand distance vector (AODV) protocol in terms of throughput, computation cost, and delay performance. Also, it has the ability to tolerate most common attacks and offers additional functionality features thereby offering a lightweight and highly secure protocol that can be extended to other critical domains like Smart Transportation Systems (STS), Smart grids, Smart buildings etc.

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Hegde, Sujay N., H. K. Krishnappa, M. A. Rajan, and Srinivas D B. "An efficient greedy task scheduling algorithm for heterogeneous inter-dependent tasks on computational grids." International Journal of Grid and Utility Computing 1, no. 1 (2020): 1. http://dx.doi.org/10.1504/ijguc.2020.10026377.

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Journal articles on the topic 'Computational grids (Computer systems)'

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