Journal articles on the topic 'Computational calculation'
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Kelley, Jason, and Chad Higgins. "Computational efficiency for the surface renewal method." Atmospheric Measurement Techniques 11, no. 4 (April 16, 2018): 2151–58. http://dx.doi.org/10.5194/amt-11-2151-2018.
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Abstract. Measuring surface fluxes using the surface renewal (SR) method requires programmatic algorithms for tabulation, algebraic calculation, and data quality control. A number of different methods have been published describing automated calibration of SR parameters. Because the SR method utilizes high-frequency (10 Hz+) measurements, some steps in the flux calculation are computationally expensive, especially when automating SR to perform many iterations of these calculations. Several new algorithms were written that perform the required calculations more efficiently and rapidly, and that tested for sensitivity to length of flux averaging period, ability to measure over a large range of lag timescales, and overall computational efficiency. These algorithms utilize signal processing techniques and algebraic simplifications that demonstrate simple modifications that dramatically improve computational efficiency. The results here complement efforts by other authors to standardize a robust and accurate computational SR method. Increased speed of computation time grants flexibility to implementing the SR method, opening new avenues for SR to be used in research, for applied monitoring, and in novel field deployments.
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Liu, Dingjin, Bo Li, and Guofeng Liu. "Calculation of Surface Offset Gathers Based on Reverse Time Migration and Its Parallel Computation with Multi-GPUs." Applied Sciences 11, no. 22 (November 12, 2021): 10687. http://dx.doi.org/10.3390/app112210687.
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As an important method for seismic data processing, reverse time migration (RTM) has high precision but involves high-intensity calculations. The calculation an RTM surface offset (shot–receiver distance) domain gathers provides intermediary data for an iterative calculation of migration and its velocity building. How to generate such data efficiently is of great significance to the industrial application of RTM. We propose a method for the calculation of surface offset gathers (SOGs) based on attribute migration, wherein, using migration calculations performed twice, the attribute profile of the surface offsets can be obtained, thus the image results can be sorted into offset gathers. Aiming at the problem of high-intensity computations required for RTM, we put forth a multi-graphic processing unit (GPU) calculative strategy, i.e., by distributing image computational domains to different GPUs for computation and by using the method of multi-stream calculations to conceal data transmission between GPUs. Ultimately, the computing original efficiency was higher relative to a single GPU, and more GPUs were used linearly. The test with a model showed that the attributive migration methods can correctly output SOGs, while the GPU parallel computation can effectively improve the computing efficiency. Therefore, it is of practical importance for this method to be expanded and applied in industries.
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Pyatkin, P. A., and E. G. Skibin. "ACCOUNT THE INFLUENCE OF DEFORMATIONS FROM PART-TIME WORK OF THE TERRITORY ON THE STRESS-STRAIN STATE OF BUILDING STRUCTURES." Construction and Geotechnics 12, no. 3 (December 15, 2021): 53–62. http://dx.doi.org/10.15593/2224-9826/2021.3.06.
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The paper considers the possibility of taking into account the deformations from the part-time work of the territory when calculating buildings in the LIRA-SAPR. The parameters of part-time work deformation have been considered and analysed. The calculation diagrams have been drawn up which take into account the additional deformations of the part-time work at the nodes at the base level of the calculation diagram in addition to the deformations of the ground settlement. Two fundamentally different computational schemes are considered - frame buildings on freestanding columnar foundations and buildings on strip or slab foundations. Calculation algorithms for these schemes for the LIRA-SAPR software package are compiled. The description of calculation schemes operation is given. Difficulties that arise when solving the task are analysed. The results of solving test tasks are given. Transformation of the computational scheme according to the developed algorithm is performed, and results of calculations for the convex and concave forms of undercutting are presented. The calculation results showed that the proposed model of calculating buildings taking into account part-time work.
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Maahury, Mirella Fonda. "MOLECULAR STRUCTURE AND ELECTRONIC PROPERTIES OF EUGENOL AND ITS ANALOGUES USING DFT." JURNAL KIMIA MULAWARMAN 19, no. 2 (May 31, 2022): 58. http://dx.doi.org/10.30872/jkm.v19i2.1123.
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Eugenol is the active molecule naturally found in clove oil. The calculations have been done for the eugenol and its derivatives computationally. This computational calculation aims to obtain a stable structure and electronic properties of eugenol, methyl eugenol, and acetyl eugenol. The computational calculation used DFT for geometry optimization in the gas phase using B3LYP functional and 6-31G(d) as the basis set. The optimized structure of eugenol and its derivatives is not planar. The presence of methoxy replacing hydroxy increases the bond length and decreases the bond angle and the dihedral. The electronic properties such as atomic charge and density of HOMO-LUMO show the difference between the three molecules.
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Braatz, R. P., P. M. Young, J. C. Doyle, and M. Morari. "Computational complexity of μ calculation." IEEE Transactions on Automatic Control 39, no. 5 (May 1994): 1000–1002. http://dx.doi.org/10.1109/9.284879.
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Ebeling, John C., Ian C. Bacon, Trent P. Bates, Scott D. Sommerfeldt, and Jonathan D. Blotter. "Improved efficiency of vibration-based sound power computation through multi-layered radiation resistance matrix symmetry." Journal of the Acoustical Society of America 151, no. 4 (April 2022): A228. http://dx.doi.org/10.1121/10.0011146.
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Calculating sound power using complex-valued surface velocities is becoming an established practice in structural acoustics with rising optimism about this method’s potential versatility compared to traditional pressure-based methods. One approach involves using a geometry-dependent acoustic radiation resistance matrix multiplied by a velocity vector to compute sound power for a given frequency range. At scale, the computational costs incurred through this calculation limits the application of this method. Given a discretized surface with constant spacing and using a well-informed average radiator area approximation, a multilayered Toeplitz symmetry exists in the radiation resistance matrix. This symmetry, its origins and necessary assumptions are explored. By exploiting the Toeplitz symmetry, computationally expensive mathematical operations that used to be performed on the entire radiation resistance matrix, can be performed on a single row of the matrix, and then expanded using the pattern that will be presented. This approach preserves accuracy and greatly accelerates the processing, as evidenced through experimental data. The approach resulted in a maximum of ∼1300% computation time reduction for single radius curved plate calculations and a ∼9,600% computation time reduction for cylindrical shell calculations. [Funding for this work was provided by the National Science Foundation (NSF).]
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Krejsa, Martin, and Juraj Kralik. "Probabilistic Computational Methods in Structural Failure Analysis." Journal of Multiscale Modelling 06, no. 03 (September 2015): 1550006. http://dx.doi.org/10.1142/s1756973715500067.
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Probabilistic methods are used in engineering where a computational model contains random variables. Each random variable in the probabilistic calculations contains uncertainties. Typical sources of uncertainties are properties of the material and production and/or assembly inaccuracies in the geometry or the environment where the structure should be located. The paper is focused on methods for the calculations of failure probabilities in structural failure and reliability analysis with special attention on newly developed probabilistic method: Direct Optimized Probabilistic Calculation (DOProC), which is highly efficient in terms of calculation time and the accuracy of the solution. The novelty of the proposed method lies in an optimized numerical integration that does not require any simulation technique. The algorithm has been implemented in mentioned software applications, and has been used several times in probabilistic tasks and probabilistic reliability assessments.
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Qin, Xinming, Honghui Shang, Lei Xu, Wei Hu, Jinlong Yang, Shigang Li, and Yunquan Zhang. "The static parallel distribution algorithms for hybrid density-functional calculations in HONPAS package." International Journal of High Performance Computing Applications 34, no. 2 (May 9, 2019): 159–68. http://dx.doi.org/10.1177/1094342019845046.
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Hybrid density-functional calculation is one of the most commonly adopted electronic structure theories in computational chemistry and materials science because of its balance between accuracy and computational cost. Recently, we have developed a novel scheme called NAO2GTO to achieve linear scaling (Order-N) calculations for hybrid density-functionals. In our scheme, the most time-consuming step is the calculation of the electron repulsion integrals (ERIs) part, so creating an even distribution of these ERIs in parallel implementation is an issue of particular importance. Here, we present two static scalable distributed algorithms for the ERIs computation. Firstly, the ERIs are distributed over ERIs shell pairs. Secondly, the ERIs are distributed over ERIs shell quartets. In both algorithms, the calculation of ERIs is independent of each other, so the communication time is minimized. We show our speedup results to demonstrate the performance of these static parallel distributed algorithms in the Hefei Order-N packages for ab initio simulations.
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Tokarev, Vyacheslav, and Nikolay Novitsky. "The method of adjustment of heat supply systems with the multistage temperature control at pumping stations." MATEC Web of Conferences 212 (2018): 02006. http://dx.doi.org/10.1051/matecconf/201821202006.
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The lowering of the temperature graph in the lower-level heat networks is often carried out by a mixture of coolant from the return pipeline at mixing pumping stations in order to maintain the set temperature of the mixed water. In this case, part of the heat carrier is not returned to the source of thermal energy, but it circulates in the circuits from the mixing station to the lower consumption nodes. The presence of such circulation flows leads to the absence of a stabilizing moment of the temperature field when it is calculated by traditional methods, as well as to the “looping” of the computational process and the impossibility of obtaining a solution. In work to overcome these problems, a new computational scheme for commissioning calculation is proposed, which is based on: (a) decomposing the calculation of the thermal-hydraulic regime into calculations of the hydraulic and temperature conditions; (b) using the conditional regulator of the ratio of the mixing station’s output costs in calculating the hydraulic regime; (c) fixing the temperature at the station’s output when calculating the temperature regime; (d) iterative calculation with correction of the setpoint of the ratio controller of the flow rate based on the calculation of the temperature regime.
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Platov, Alexander J., and Juri I. Platov. "Efficient computation of ship’s wave-making resistance using michell’s integral." Russian Journal of Water Transport, no. 73 (December 20, 2022): 206–15. http://dx.doi.org/10.37890/jwt.vi73.327.
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The aim of the present paper is to find efficient method of computation the wave-making resistance of a ship using mitchell’s integral. The computational schemes described in publications suggest the use of simple quadratures (trapezoidal and Simpson’s rule) with a fixed number of integration’s intervals. This approach assumes manual setup of the algorithm for calculating the wave-making resistance for each new ship and makes it difficult to estimate the error of the obtained results. It is shown that the use of these simple quadratures makes it possible to obtain reliable results, but at the cost of tens of billions of calculations of the ship's surface function. The applicability of more advanced universal quadratures for calculating the mitchell’s integral is investigated: adaptive Newton-Cotes rules, Gauss-Kronrod rules and Clenshaw-Curtis quadratures. As a result, it is established that the Clenshaw-Curtis quadrature provides a reliable and efficient calculation of the mitchell’s integral. The computational scheme using this quadrature allows you to build an automatic algorithm for calculating the ship's wave-making resistance by type ship method.
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Kik, Tomasz. "Computational Techniques in Numerical Simulations of Arc and Laser Welding Processes." Materials 13, no. 3 (January 29, 2020): 608. http://dx.doi.org/10.3390/ma13030608.
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The article presents a comparison of modern computational techniques used in numerical analyses of welding processes. The principles of the “transient” technique calculations with a moving heat source, the “macro-bead” (MBD) technique, with an imposed thermal cycle on a selected weld bead section and the “local–global” approach with shrinkage calculation technique were described. They can be used, depending on the variant chosen, both for individual, simple weld joints and those made of many beads or constructions containing dozens of welds and welded elements. Differences in the obtained results and time needed to perform calculations with four different calculation examples of single and multipass arc and laser beam welding processes were presented. The results of calculations of displacements and stresses distributions in the welded joints using various computational techniques were compared, as well as the calculation times with the described techniques. The numerical analyses in the SYSWELD software package have shown the differences between the described computational techniques, as well as an understanding of the benefits and disadvantages of using each of them. This knowledge allows preparing an efficient and fast optimization of the welding processes, often aimed at minimizing deformations in the first place, as well as detection of potential defects of both simple and complex welded structures. In general, the possibilities and flexibility of modern numerical calculation software have been presented.
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Kurniadi, Rizal. "Application of The Computational Semi-Empirical Method in Calculating The Fission Yield with Reference to The JENDL Data." Indonesian Journal of Physics 33, no. 2 (December 22, 2022): 29–35. http://dx.doi.org/10.5614/itb.ijp.2022.33.2.5.
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Fission Yield calculation techniques can be completed in various ways. In this work, other calculation techniques will be described. Namely, a semi-empirical technique that utilizes random numbers. This semi-empirical method can produce fitting parameters to obtain other physical quantities. Because it uses a random number initiator, computations can be completed in parallel. Therefore, the computation time is shorter. This paper will show in sequence the steps of this technique. The calculation begins by assigning a value to the incident energy and random position of the nucleons, and then ends after fission products occur. This paper only describes the process of calculating the Fission Yield for several U isotopes.
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An, Leike, Qingmei Li, Chengqi Cheng, Bo Chen, and Tengteng Qu. "Spatial Grid-Based Position Calculation Method for Satellite-Ground Communication Links." Remote Sensing 14, no. 12 (June 11, 2022): 2808. http://dx.doi.org/10.3390/rs14122808.
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With the rapid development of global satellite constellation clusters and the popularity of ground-based intelligent terminals, the interconnection between large-scale low Earth orbit satellites and ground base stations has become more frequent. The calculation of satellite position requires a large number of floating point square calculations and coordinate system conversions, with high computational complexity and long computation time. Based on the grid encoding method of GeoSOT, we propose a GeoSOT-based grid calculation for a satellite-ground position (GCSGP) model. We use binary bit operations instead of complex topological operations and floating point calculations, and use grid distance calculations instead of existing angle calculations. Thus, the relative positions of satellites to the ground can be quickly calculated and thus connected to more suitable satellites quickly. The results of the grid calculation were verified by simulation experiments. The calculation speed was improved by about 82% compared with the traditional method. The test accuracy error of the 10-level grid at a terminal 45° inclination was less than 1% at all heights, and the maximum error of the 10-level grid within a 10–45° inclination was 7.2% at 10,000 km altitude, which provides theoretical support for the subsequent grid space calculation.
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Wang, Shengquan, Chao Wang, Yong Cai, and Guangyao Li. "A novel parallel finite element procedure for nonlinear dynamic problems using GPU and mixed-precision algorithm." Engineering Computations 37, no. 6 (February 22, 2020): 2193–211. http://dx.doi.org/10.1108/ec-07-2019-0328.
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Purpose The purpose of this paper is to improve the computational speed of solving nonlinear dynamics by using parallel methods and mixed-precision algorithm on graphic processing units (GPUs). The computational efficiency of traditional central processing units (CPUs)-based computer aided engineering software has been difficult to satisfy the needs of scientific research and practical engineering, especially for nonlinear dynamic problems. Besides, when calculations are performed on GPUs, double-precision operations are slower than single-precision operations. So this paper implemented mixed precision for nonlinear dynamic problem simulation using Belytschko-Tsay (BT) shell element on GPU. Design/methodology/approach To minimize data transfer between heterogeneous architectures, the parallel computation of the fully explicit finite element (FE) calculation is realized using a vectorized thread-level parallelism algorithm. An asynchronous data transmission strategy and a novel dependency relationship link-based method, for efficiently solving parallel explicit shell element equations, are used to improve the GPU utilization ratio. Finally, this paper implements mixed precision for nonlinear dynamic problems simulation using the BT shell element on a GPU and compare it to the CPU-based serially executed program and a GPU-based double-precision parallel computing program. Findings For a car body model containing approximately 5.3 million degrees of freedom, the computational speed is improved 25 times over CPU sequential computation, and approximately 10% over double-precision parallel computing method. The accuracy error of the mixed-precision computation is small and can satisfy the requirements of practical engineering problems. Originality/value This paper realized a novel FE parallel computing procedure for nonlinear dynamic problems using mixed-precision algorithm on CPU-GPU platform. Compared with the CPU serial program, the program implemented in this article obtains a 25 times acceleration ratio when calculating the model of 883,168 elements, which greatly improves the calculation speed for solving nonlinear dynamic problems.
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SAKK, ERIC. "ON THE COMPUTATION OF MOLECULAR SURFACE CORRELATIONS FOR PROTEIN DOCKING USING FOURIER TECHNIQUES." Journal of Bioinformatics and Computational Biology 05, no. 04 (August 2007): 915–35. http://dx.doi.org/10.1142/s0219720007002916.
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The computation of surface correlations using a variety of molecular models has been applied to the unbound protein docking problem. Because of the computational complexity involved in examining all possible molecular orientations, the fast Fourier transform (FFT) (a fast numerical implementation of the discrete Fourier transform (DFT)) is generally applied to minimize the number of calculations. This approach is rooted in the convolution theorem which allows one to inverse transform the product of two DFTs in order to perform the correlation calculation. However, such a DFT calculation results in a cyclic or "circular" correlation which, in general, does not lead to the same result as the linear correlation desired for the docking problem. In this work, we provide computational bounds for constructing molecular models used in the molecular surface correlation problem. The derived bounds are then shown to be consistent with various intuitive guidelines previously reported in the protein docking literature. Finally, these bounds are applied to different molecular models in order to investigate their effect on the correlation calculation.
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Li, Yinghui, and Russell T. Johns. "Rapid Flash Calculations for Compositional Simulation." SPE Reservoir Evaluation & Engineering 9, no. 05 (October 1, 2006): 521–29. http://dx.doi.org/10.2118/95732-pa.
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Summary The computational time for conventional flash calculations increases significantly with the number of components, making it impractical for use in many fine-grid compositional simulations and other applications. Previous research to increase flash-calculation speed has been limited to those with zero binary interaction parameters (BIPs) or approximate methods based on an eigenvalue analysis of the binary interaction matrix. Practical flash calculations, however, nearly always have some nonzero BIPs. Further, the accuracy and speed of the eigenvalue methods varies depending on the choice and number of the dominant eigenvalues. This paper presents a new and simple method for significantly increasing the speed of flash calculations for any number of nonzero BIPs. The approach requires the solution of up to six reduced parameters regardless of fluid complexity or the number of components and is based on decomposing the BIPs into two parameters using a simple quadratic expression. The new approach is exact in that the equilibrium-phase compositions for the same BIPs are identical to those with the conventional flash calculation; no eigenvalue analysis is required. Further, the new approach eliminates the Rachford-Rice procedure (1952) and is more robust than the conventional flash-calculation procedure. We demonstrate the new approach for several example fluids and show that speedup by a factor of approximately 3 to 20 is obtained over conventional flash calculations, depending on the number of components. Introduction Gas injection into oil reservoirs results in complex interactions of flow with phase behavior that often are not modeled accurately by black-oil simulation. This is especially true for miscible or nearly miscible floods in which significant mass transfer occurs between the hydrocarbon phases. Such floods are best modeled by compositional simulation. A significant disadvantage of compositional simulation, however, is that it is much more computationally intensive than black-oil simulation. The primary reason for the increased computational time is the result of solving repeated flash calculations with cubic equations of state (EOS). Research has shown that EOS flash calculations can occupy 50 to 70% of total computational time in compositional simulations (Stenby and Wang 1993; Chang 1990). This is also true for other applications, such as multiphase flow in pipelines. The use of fewer pseudocomponents can reduce the flash computation time, but fewer components results in less accuracy (Hong 1982; Liu 2001; Egwuenu et al. 2005). This is especially true in multicontact miscible displacements, in which miscibility is developed by a combined condensing/vaporizing drive process (Zick 1986; Johns et al. 1993; Egwuenu et al. 2005). Fluid characterization by pseudocomponent models can be improved by tuning to the analytical minimum miscibility enrichment or minimum miscibility pressure (Johns et al. 1994), but those models still require significant computational time, even for fewer pseudocomponents. Another way to reduce computation time is to reduce the number of gridblocks. With coarse grids, however, numerical dispersion is large, which may cloud the results (Solano et al. 2001). Ideally, fine grids should be used that better match the level of dispersion found at the field scale. More recently, methods have been examined to find reduced parameters for flash calculations. Michelsen (1982a, 1982b, 1986) significantly increased flash-calculation speed by finding three reduced parameters, regardless of the number of components. His method, however, assumes zero BIPs, which is too restrictive for real fluid characterization. Michelsen also gave a practical method for stability calculations using the tangent plane distance (TPD) (Michelsen 1982b).
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Тупов, Vladimir Tupov, Черешнева, and Olesya Chereshneva. "Calculation and Research of Traffic Flow Noise Abatement by Noise Screens." Safety in Technosphere 3, no. 5 (October 25, 2014): 17–24. http://dx.doi.org/10.12737/6020.
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Noise screen (NS) is an efficient and rather low-cost way of protection of highway-area territories against traffic flow noise (TFN). In engineering calculations NS are often considered infinite, disregarding the phenomenon of sound diffraction on its lateral edges. Presented computational method allows considering diffraction processes along all NS perimeter thus increasing accuracy of calculation of screen installation effect. The research also focuses on contribution of the sound diffracted on lateral edges of the screen to composite TFN at computational point (CP) depending on its position on NS, NS’s size, and sound-absorbing qualities of landscape around highway. Mathematical relations for calculating noise abatement have been built due to a number of factors instead of traditionally applied tables, nomograms and graphics thus simplifying programming process.
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Holloway, Ian, Aihua Wood, and Alexander Alekseenko. "Acceleration of Boltzmann Collision Integral Calculation Using Machine Learning." Mathematics 9, no. 12 (June 15, 2021): 1384. http://dx.doi.org/10.3390/math9121384.
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The Boltzmann equation is essential to the accurate modeling of rarefied gases. Unfortunately, traditional numerical solvers for this equation are too computationally expensive for many practical applications. With modern interest in hypersonic flight and plasma flows, to which the Boltzmann equation is relevant, there would be immediate value in an efficient simulation method. The collision integral component of the equation is the main contributor of the large complexity. A plethora of new mathematical and numerical approaches have been proposed in an effort to reduce the computational cost of solving the Boltzmann collision integral, yet it still remains prohibitively expensive for large problems. This paper aims to accelerate the computation of this integral via machine learning methods. In particular, we build a deep convolutional neural network to encode/decode the solution vector, and enforce conservation laws during post-processing of the collision integral before each time-step. Our preliminary results for the spatially homogeneous Boltzmann equation show a drastic reduction of computational cost. Specifically, our algorithm requires O(n3) operations, while asymptotically converging direct discretization algorithms require O(n6), where n is the number of discrete velocity points in one velocity dimension. Our method demonstrated a speed up of 270 times compared to these methods while still maintaining reasonable accuracy.
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Wang, Jun, Qing Fen Li, and Er Bao Liu. "Computational Program for Non-Equilibrium Grain Boundary Segregation Kinetics." Key Engineering Materials 385-387 (July 2008): 65–68. http://dx.doi.org/10.4028/www.scientific.net/kem.385-387.65.
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The solute segregation to grain boundaries may be classified into equilibrium and non-equilibrium segregation. The models and kinetics calculation equations were proved in previous work. However, the computational task for grain-boundary segregation kinetics process is complex and cumbersome as it can involve a vast amount of numerical data. It is therefore necessary to develop an easily usable computational program which can provide the researchers with a powerful tool in grain-boundary segregation kinetics process analysis in addition to having a sound theory. A computational program of non-equilibrium grain-boundary segregation (NGS) kinetics of solute is therefore developed in this paper. It includes programs for critical time calculation, effective time calculation and diffusion coefficients calculation, the program of Auger Electron Spectroscopy test data disposal, the program of curve fitting and the program of NGS kinetics simulation. A simulation example by using the computation program of NGS kinetic equations is in good accordance with the experimental observation of phosphorus in steel 12Cr1MoV. The computational program of NGS is therefore proved to be appropriate and helpful.
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Zhou, Hua Xiang, Zheng Zhou, and Jing Ping Liu. "Theoretical and Computational Research of Heat Radiant Transfer in Cylinder." Applied Mechanics and Materials 628 (September 2014): 311–16. http://dx.doi.org/10.4028/www.scientific.net/amm.628.311.
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In order to obtain the radiation heat transfer theory and calculation methods, the movement of the gas particles, location, intensity, temperature, are researched in cylinder under different conditions with combustion system and the mode of heat transfer. Under high temperature conditions in the cylinder, the gas radiation heat transfer is researched in the complex heat transfer theory. A statistical correlation K narrow band model, a mean absorption coefficient, a gas line databases, by-line calculation method are found, through research and analysis emissivity, transmittance, absorption coefficient, typical models, mathematical equations, database, calculation methods. Examine the distribution performance of each database for different media concentration and temperature, a statistical narrow-band band parametric model accuracy is tested, using statistical narrow band model, the results of the use of by-line method. Research shows: selected spectral database, calculation method has a greater impact on the results. The research also shows the result coincides calculations based by-line HITEWP2010 database method, whether radiant heat or wall flux, statistical narrow band model. These are supplied to the internal combustion engine cylinder design.
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Stephens, Hunter, Q. Jackie Wu, and Qiuwen Wu. "Introducing matrix sparsity with kernel truncation into dose calculations for fluence optimization." Biomedical Physics & Engineering Express 8, no. 1 (November 12, 2021): 017001. http://dx.doi.org/10.1088/2057-1976/ac35f8.
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Abstract Deep learning algorithms for radiation therapy treatment planning automation require large patient datasets and complex architectures that often take hundreds of hours to train. Some of these algorithms require constant dose updating (such as with reinforcement learning) and may take days. When these algorithms rely on commerical treatment planning systems to perform dose calculations, the data pipeline becomes the bottleneck of the entire algorithm’s efficiency. Further, uniformly accurate distributions are not always needed for the training and approximations can be introduced to speed up the process without affecting the outcome. These approximations not only speed up the calculation process, but allow for custom algorithms to be written specifically for the purposes of use in AI/ML applications where the dose and fluence must be calculated a multitude of times for a multitude of different situations. Here we present and investigate the effect of introducing matrix sparsity through kernel truncation on the dose calculation for the purposes of fluence optimzation within these AI/ML algorithms. The basis for this algorithm relies on voxel discrimination in which numerous voxels are pruned from the computationally expensive part of the calculation. This results in a significant reduction in computation time and storage. Comparing our dose calculation against calculations in both a water phantom and patient anatomy in Eclipse without heterogenity corrections produced gamma index passing rates around 99% for individual and composite beams with uniform fluence and around 98% for beams with a modulated fluence. The resulting sparsity introduces a reduction in computational time and space proportional to the square of the sparsity tolerance with a potential decrease in cost greater than 10 times that of a dense calculation allowing not only for faster caluclations but for calculations that a dense algorithm could not perform on the same system.
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RODRIGUES, B. O., L. A. C. P. DA MOTA, and L. G. S. DUARTE. "NUMERICAL CALCULATION WITH ARBITRARY PRECISION." International Journal of Modern Physics E 16, no. 09 (October 2007): 3045–48. http://dx.doi.org/10.1142/s0218301307009014.
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The vast use of computers on scientific numerical computation makes the awareness of the limited precision that these machines are able to provide us an essential matter. A limited and insufficient precision allied to the truncation and rounding errors may induce the user to incorrect interpretation of his or her answer. In this work, we have developed a computational package to minimize this kind of error by offering arbitrary precision numbers and calculation. This is very important in Physics where we can work with numbers too small and too big simultaneously.
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Vlasyuk, P. E., A. V. Chernyshev, I. R. Chinyayev, and A. V. Fominykh. "Calculation and Theoretical Study of Regimes of the Working Medium Flow in a Slide Gate Valve for Technological Lines in the Oil and Gas Industry." Proceedings of Higher Educational Institutions. Маchine Building, no. 5 (746) (May 2022): 43–51. http://dx.doi.org/10.18698/0536-1044-2022-5-43-51.
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Slide gate valves are widely used as shut-off and control valves in technological lines of the oil and gas industry. The most important tasks that arise when designing a gate valve include the calculation of the hydraulic characteristics of the working medium flow and the determination of throughput. The article presents an overview of the main methods for calculating the throughput of pipeline fittings, indicates their advantages and drawbacks. It proposes a method for determining the throughput and calculating the hydraulic characteristics of the working medium flow of a high-pressure slide gate valve based on a computational-theoretical study using a modern complex of engineering analysis. A mathematical model of the working medium flow was developed and a numerical calculation performed. The correctness of the operation of the mathematical model was confirmed by comparing the data of computational-theoretical and experimental research. Based on the results of calculations and assessment of their correspondence to the real flow process in the physical prototype of the slide gate valve, conclusions were drawn about the applicability of the mathematical model.
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Candela Esclapez, Alfredo, Miguel López García, Sergio Valero Verdú, and Carolina Senabre Blanes. "Reduction of Computational Burden and Accuracy Maximization in Short-Term Load Forecasting." Energies 15, no. 10 (May 17, 2022): 3670. http://dx.doi.org/10.3390/en15103670.
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Electrical energy is consumed at the same time as it is generated, since its storage is unfeasible. Therefore, short-term load forecasting is needed to manage energy operations. Due to better energy management, precise load forecasting indirectly saves money and CO2 emissions. In Europe, owing to directives and new technologies, prediction systems will be on a quarter-hour basis, which will reduce computation time and increase the computational burden. Therefore, a predictive system may not dispose of sufficient time to compute all future forecasts. Prediction systems perform calculations throughout the day, calculating the same forecasts repeatedly as the predicted time approaches. However, there are forecasts that are no more accurate than others that have already been made. If previous forecasts are used preferentially over these, then computational burden will be saved while accuracy increases. In this way, it will be possible to optimize the schedule of future quarter-hour systems and fulfill the execution time limits. This paper offers an algorithm to estimate which forecasts provide greater accuracy than previous ones, and then make a forecasting schedule. The algorithm has been applied to the forecasting system of the Spanish electricity operator, obtaining a calculation schedule that achieves better accuracy and involves less computational burden. This new algorithm could be applied to other forecasting systems in order to speed up computation times and to reduce forecasting errors.
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Marzhan, Danabayeva, Dairabayev Maxat, Autayeva Akbota, Kulakhmet Moldabek, Kenzhebekova Rabiga, and Galiya Rysbayeva. "The development of computational skills of visually impaired children of primary classes." Cypriot Journal of Educational Sciences 17, no. 2 (February 28, 2022): 451–63. http://dx.doi.org/10.18844/cjes.v17i2.6848.
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With this study, it is aimed to improve the calculation skills of visually impaired children in elementary grades. In this context, it is expected that mathematical calculation skills will gain meaning and target behaviours will be changed with the help of technology for visually impaired children. The study group of the study consists of 78 primary school students who continue to study in voluntary primary school classes. The research was conducted in the fall academic year of 2021–2022. In the study, elementary school students were given training on calculations in a 4-week classroom environment in order to gain calculation and mathematical skills. In the study, the ‘calculation skills’ measurement tool was used to collect data. The measurement tool used in the study was delivered to primary school students with the help of their families and collected. The analysis of the data was carried out using the SPSS programme; frequency analysis was carried out using the t-test; and the results obtained were added to the study accompanied by tables. As a result of the research, it was found that the calculation and mathematics skills of primary school students have a positive effect on education, as well as on motivation in their studies.
Keywords: Elementary school students, calculation skills, visually impaired students;
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Tschur, Nikolay, Sergey Polovko, and Andrey Deulin. "Application of the computational fluid dynamics methods to obtain the characteristics of AUV transient responses." Robotics and Technical Cybernetics 8, no. 4 (December 30, 2020): 287–95. http://dx.doi.org/10.31776/rtcj.8405.
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The purpose of this work is to create the most accurate mathematical model of the underwater vehicle dynamics. In fact, the proposed model should be an alternative to full-scale testing of the device. The paper presents a calculation method that implements coupled calculations of the underwater vehicle dynamics and the hydrodynamics of the fluid, flowing around it. From the point of view of mechanics and hydrodynamics, this approach is the most accurate method for modeling the device dynamics in the presence of arbitrary control actions. The main advantage of the proposed calculation method is the conservative approximation scheme for hydrodynamic calculations, which is extremely important when performing non-stationary calculations. In addition, the proposed method requires less computational resources than other currently used coupled calculations methods. The proposed method was verified on a large data volume received from real autonomous underwater vehicles (AUV) field tests and showed high accuracy in reproducing full-scale data. The developed calculation method was used for the designing AUV control system and showed its high efficiency.
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Gileva, Lyubov, Sergey Kartashov, Anatoliy Zuev, and Vyacheslav Ivanov. "Verification of the CFD calculation for the centrifugal compressor medium flow model stages with the help of supercomputer." MATEC Web of Conferences 245 (2018): 09011. http://dx.doi.org/10.1051/matecconf/201824509011.
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The goal of this work is to develop recommendations for the calculating problem formulation of the medium flow centrifugal compressor characteristics by computational fluid dynamics methods with the assessment of the computing resources necessary costs. Calculations are made on supercomputers of SPbPU “Polytechnic” and “DeltaCluster”. The object of the research is the centrifugal compressor stage for which the flow investigation has been held in the whole passage. The calculations result comparison with the practical experiment data for the whole working characteristics are shown in this work. The leakage in the lap seals and between the disks gaps investigation work has been made. The calculation of the whole 2π flat pattern has been made and also the influence on the calculation results of the between mesh interfaces has been analyzed.
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Galchenko, Vitaliy, Ihor Shlapak, and Volodymyr Gulik. "Computational benchmark for fuel assembly of VVER-1000 using the Monte Carlo Serpent code." Nuclear Technology and Radiation Protection 33, no. 1 (2018): 24–30. http://dx.doi.org/10.2298/ntrp1801024g.
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The use of a new Monte Carlo Serpent code for the calculation of water-cooled reactors is presented and a calculation scheme of the fuel assembly for VVER-1000 reactors developed. The calculation of neutron-physical characteristics for the fuel assembly of VVER-1000 is carried out for different states and the results obtained by the Serpent model compared with the results of other reactor codes. The analyses of these results are presented in the paper submitted here. Based on this article, the Monte Carlo Serpent code could be used for neutron-physical calculations of VVER-1000 reactors.
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Tailakova, Anna, and Alexander Pimonov. "Optimization Methods and Algorithms for Calculating the Construction of Non-Rigid Pavement for Technological Quarries Roads." E3S Web of Conferences 134 (2019): 01007. http://dx.doi.org/10.1051/e3sconf/201913401007.
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Previously developed by the authors of the optimization model for calculating the construction of non-rigid pavement of public roads is proposed to be used for the calculation of the construction of pavement technological career roads. The article describes the optimization methods and algorithms for calculating the construction of pavement. Possibilities of using methods of coordinate-wise descent, multi-start, dynamic programming for the selection of the optimal construction of pavement are presented. Application of genetic algorithms for the decision of an optimization problem of calculation of a construction of pavements on the basis of comparison of their efficiency with efficiency of search methods is proved. Described results of computational experiment of selection of genetic algorithm operators to reduce the volume of calculations and ensure the stability of the results.
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Alekseyev, D. P., and A. A. Sheypak. "Comparative analysis of methods for calculating airlift units." Izvestiya MGTU MAMI 4, no. 1-4 (July 10, 2014): 111–16. http://dx.doi.org/10.17816/2074-0530-67490.
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In the paper the authors present a calculation of the characteristics of an airlift unit based on the methods of computational fluid dynamics (CFD). As a result of numerical simulation of unit operation its characteristics were received as well as the scalar distribution field of the gas phase. The basic methodologies for calculating airlift units such as Geyer method, a method developed in Donetsk National Technical University (DonNTU) and cfd-method are considered. A comparative analysis of the accuracy of these methods was conducted. It was shown that the results of calculations based on computational fluid dynamics and results obtained by the method of DonNTU are consistent with each other.
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Rocha, Rênica Alves de Morais, Thaís Forest Giacomello, Antonio Maia de Jesus Chaves Neto, Gunar Vingre Da Silva Mota, and Fabio Luiz Paranhos Costa. "Carbon-13 Nuclear Magnetic Resonance Chemical Shift Calculation Protocol Applied to Rigid Triterpenes Molecules." Advanced Science, Engineering and Medicine 12, no. 8 (August 1, 2020): 995–1001. http://dx.doi.org/10.1166/asem.2020.2636.
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Nuclear magnetic resonance spectroscopy is one of the most powerful experimental techniques for obtaining three-dimensional structures of complex molecules, mainly for the analysis of the relative and absolute configurations of organic compounds. For this reason, this has become one of the most promising tools in the field of chemistry. From the theoretical point of view, advanced computational protocols have been developed for calculating nuclear magnetic resonance, mainly hydrogen-1 and carbon-13, parameters of isolated molecules, in which the environmental effects are neglected. These effects are predominantly related to the inherently large size of such systems, making conventional ab initio theories either very computationally demanding or even prohibitive. Despite the current advances in spectroscopic techniques, instances of revision of structures erroneously established for natural products are still common in the literature. Therefore, it is still necessary the development of quantum-chemical protocols that may assist in the correct structural determination of these compounds. This work aimed to test a universal scaling factor, based on a linear regression, for the calculation of carbon-13 nuclear magnetic resonance chemical shifts for rigid molecules, which has low computational cost and great accuracy to aid in the structural determination of natural products. The carbon-13 chemical shifts were calculated using the mPW1PW91/3-21G level of theory. Scaled chemical shifts were obtained according to the relation: 1.14x(calculated chemical shifts)–4.71. To test the application of the created scaling factor to problems related to stereochemistry, we investigated its ability to differentiate pentacyclic triterpenes regioisomers. Our results show that the mPW1PW91/3-21G//PM7 level of theory applied to the calculations, together with the use of the scaling factor, is an efficient and low-cost tool as an alternative to computational requirement approaches, usually applied to the calculation of carbon-13 nuclear magnetic resonance chemical shifts.
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KARPENKO, N. P., and M. A. SHIRYAEVA. "METHODS OF FORECAST CALCULATION OF GROUND WATER BACKWATER IN THE ZONE OF HYDRAULIC STRUCTURES INFLUENCE." Prirodoobustrojstvo, no. 5 (2020): 109–16. http://dx.doi.org/10.26897/1997-6011-2020-5-109-116.
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The purpose of the work is to consider methods for calculating the forecast of groundwater backwater in the zone of influence of hydraulic structures. The analysis of analytical dependences of calculation of the forecast of groundwater backwater for various calculation schemes is carried out. For a homogeneous scheme of the geofiltration structure, a numerical model is proposed and a computational program for calculating the groundwater backwater is developed. It allows calculating the groundwater backwater from the channel at any time in the discrete mode. To simplify the solution of the problem of calculating the groundwater backwater, a computer program was created in the programming language Phyton Version 8.3 which quickly solves this hydrogeological problem. A possible range of geofiltration parameters is proposed for calculating the groundwater backwater near main channels. The adaptation and implementation of the software model was carried out for a specific object – the Bolshoy Stavropol channel-5, for which forecast calculations were made. The results of predictive calculations of groundwater backwater are the basis for the assessment of areas of possible flooding – the territory within which the level of ground water increases as a result of their backup by a hydraulic structure.
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Borovkov, Maxim, and Tatjana Savyolova. "The computational approaches to calculate normal distributions on the rotation group." Journal of Applied Crystallography 40, no. 3 (May 15, 2007): 449–55. http://dx.doi.org/10.1107/s0021889807005626.
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There are several kinds of probability distribution widely used in quantitative texture analysis. One of them is the normal (Gaussian) distribution. The main application of the normal distribution is the orientation distribution function and pole-figure approximation on the rotation group SO(3) and sphere S2accordingly. The calculation of the normal distribution is a complicated computational task. There are currently several methods for calculating the normal distribution. Each of these methods has its advantages and disadvantages. The classical method of calculation by Fourier series summation is effective enough only in the case of continuous texture approximation. In the case of sharp texture approximation, the analytical approach is more suitable and effective. These two calculation methods result in a continuous function. The other method allows a discrete orientation set to be obtained, corresponding to a random sample of normal distribution similar to experimental electron backscatter diffraction data. This algorithm represents a statistical simulation by the particularized Monte Carlo method. A short review of these computational approaches to the calculation of normal distributions on the rotation group is presented.
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Thormann, R., and S. Timme. "Efficient aerodynamic derivative calculation in three-dimensional transonic flow." Aeronautical Journal 121, no. 1244 (July 10, 2017): 1464–78. http://dx.doi.org/10.1017/aer.2017.66.
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ABSTRACTOne key task in computational aeroelasticity is to calculate frequency response functions of aerodynamic coefficients due to structural excitation or external disturbance. Computational fluid dynamics methods are applied for this task at edge-of-envelope flow conditions. Assuming a dynamically linear response around a non-linear steady state, two computationally efficient approaches in time and frequency domain are discussed. A non-periodic, time-domain function can be used, on the one hand, to excite a broad frequency range simultaneously giving the frequency response function in a single non-linear, time-marching simulation. The frequency-domain approach, on the other hand, solves a large but sparse linear system of equations, resulting from the linearisation about the non-linear steady state for each frequency of interest successively. Results are presented for a NACA 0010 aerofoil and a generic civil aircraft configuration in very challenging transonic flow conditions with strong shock-wave/boundary-layer interaction in the pre-buffet regime. Computational cost savings of up to 1 order of magnitude are observed in the time domain for the all-frequencies-at-once approach compared with single-frequency simulations, while an additional order of magnitude is obtained for the frequency-domain method. The paper demonstrates the readiness of computational aeroelasticity tools at edge-of-envelope flow conditions.
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Maahury, Mirella Fonda, and Matthew Adi Honey Amos. "Computational Calculation of Nitrobenzene and Its Derivatives." Indo. J. Chem. Res. 10, no. 2 (September 30, 2022): 88–92. http://dx.doi.org/10.30598//ijcr.2022.10-mir.
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Nitrobenzene is one of benzene derivatives. Nitrobenzene can be found naturally and also from the synthesis process. Nitrobenzene is used as a raw material to synthesize aniline, textile dyes, pesticides, and drugs. Nitrobenzene is a solvent in the paint industry. The computational calculation was performed for nitrobenzene and its derivatives. Nitrobenzene and its four nitrobenzene derivatives have been optimized using density functional theory/B3LYP functional. The basis set is 3-21G(d). The optimized structure from geometry optimization of the nitrobenzene and its derivatives are in one plane (planar). The parameter structure is changed when substituents change. The bond length increases, and the bond angle decreases when substituents are present.
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Zhao, Jiaqi, Shuai Hu, Xichuan Liu, and Shulei Li. "The Computational Optimization of the Invariant Imbedding T Matrix Method for the Particles with N-Fold Symmetry." Remote Sensing 14, no. 16 (August 19, 2022): 4061. http://dx.doi.org/10.3390/rs14164061.
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The invariant imbedding T-matrix (IIM T-matrix) model is regarded as one of the most promising models for calculating the scattering parameters of non-spherical particles. However, the IIM T-matrix model needs to be iterated along the radial direction when calculating the T-matrix, which involves complex calculations such as matrix inversion and multiplication. Therefore, how to improve its computational efficiency is an important problem to be solved. Focused on particles with N-fold symmetric geometry, this paper deduced the symmetry in the calculation process of the IIM T-matrix model, derived the block iteration scheme of the T-matrix, and contracted the IIM T-matrix program for particles with N-fold symmetric geometry. Discrete Dipole Approximation (DDA) and Geometrical Optics Approximation (IGOA) were employed to verify the accuracy of the improved IIM T-matrix model. The results show that the six phase matrix elements (P11, P12/P11, P22/P11, P33/P11, P34/P11 and P44/P11) calculated by our model are in good agreement with other models. The computational efficiency of the improved IIM T-matrix model was further investigated. As demonstrated by the results, the computational efficiency for the particles with N-fold symmetry improved by nearly 70% with the improvement of the symmetry of U matrix and T matrix. In conclusion, the improved model can remarkably reduce the calculation time while maintaining high accuracy.
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Indeykin, Andrey, Olga Kuranova, Andrey Chernykh, and Georgiy Chanturiya. "On the improvement of computational accuracy during the construction of transportation lines." Proceedings of Petersburg Transport University, no. 3 (September 20, 2018): 391–98. http://dx.doi.org/10.20295/1815-588x-2018-3-391-398.
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Objective: To obtain analytic dependences for profile cubage volume calculation of subgrades (side hill fills), ditch cuts (side hill cuts), as well as borrow pits, soil banks, drainage ditches and other structures. Methods: Integral calculus and stereometry was applied. Results: New analytic dependencies for profile cubage volume calculation of subgrades (side hill fills), ditch cuts (side hill cuts), borrow pits, soil banks and drainage ditches were deducted. Relative errors of calculating the given profile cubage volume were determined in comparison with conventional methods for calculating the values in question. Mathematical demonstration of the given analytic dependencies, as well as the analysis of the latter was carried out. Practical importance: Computational accuracy of profile cubage volume of subgrades (side hill fills), ditch cuts (side hill cuts), borrow pits, soil banks and drainage ditches may be improved based on the examined dependencies. Research results may be applied in the design of information systems. The latter promptly implement the introduced analytic dependencies of more effective calculation indices and test planning of large earthwork volumes.
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Zuend, A., and J. H. Seinfeld. "Modeling the gas-particle partitioning of secondary organic aerosol: the importance of liquid-liquid phase separation." Atmospheric Chemistry and Physics Discussions 12, no. 1 (January 24, 2012): 2199–258. http://dx.doi.org/10.5194/acpd-12-2199-2012.
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Abstract. The partitioning of semivolatile organic compounds between the gas phase and aerosol particles is an important source of secondary organic aerosol (SOA). Gas-particle partitioning of organic and inorganic species is influenced by the physical state and water content of aerosols, and therefore ambient relative humidity (RH), as well as temperature and organic loading levels. We introduce a novel combination of the thermodynamic models AIOMFAC (for liquid mixture non-ideality) and EVAPORATION (for pure compound vapor pressures) with oxidation product information from the Master Chemical Mechanism (MCM) for the computation of gas-particle partitioning of organic compounds and water. The presence and impact of a liquid-liquid phase separation in the condensed phase is calculated as a function of variations in relative humidity, organic loading levels, and associated changes in aerosol composition. We show that a complex system of water, ammonium sulfate, and SOA from the ozonolysis of α-pinene exhibits liquid-liquid phase separation over a wide range of relative humidities (simulated from 30% to 99% RH). Since fully coupled phase separation and gas-particle partitioning calculations are computationally expensive, different simplified model approaches are tested with regards to computational costs and accuracy of predictions compared to the benchmark calculation. Both forcing a liquid one-phase aerosol considering non-ideal mixing or assuming an ideal mixture bear the potential for vastly incorrect partitioning predictions. Assuming an ideal mixture leads to substantial overestimation of the particulate organic mass, at high RH by more than 200%. Moreover, the simplified one-phase cases stress two key points for accurate gas-particle partitioning calculations: (1) non-ideality in the condensed phase needs to be considered and (2) liquid-liquid phase separation is a consequence of considerable deviations from ideal mixing in solutions containing inorganic ions and organics that cannot be ignored. Computationally much more efficient calculations relying on the assumption of a complete organic/electrolyte phase separation below a certain RH successfully reproduce gas-particle partitioning in systems in which the average oxygen-to-carbon (O:C) ratio is lower than ~0.6, as in the case of α-pinene SOA, and bear the potential for implementation in atmospheric chemical transport models and chemistry-climate models. A full equilibrium calculation is the method of choice for accurate offline (box model) computations, where high computational costs are acceptable. Such a calculation enables the most detailed predictions of phase compositions and provides necessary information on whether assuming a complete organic/electrolyte phase separation is a good approximation for a given aerosol system. Based on the group-contribution concept of AIOMFAC and O:C ratios as a proxy for polarity and hygroscopicity of organic mixtures, the results from the α-pinene system are also discussed from a more general point of view.
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Zuend, A., and J. H. Seinfeld. "Modeling the gas-particle partitioning of secondary organic aerosol: the importance of liquid-liquid phase separation." Atmospheric Chemistry and Physics 12, no. 9 (May 3, 2012): 3857–82. http://dx.doi.org/10.5194/acp-12-3857-2012.
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Abstract. The partitioning of semivolatile organic compounds between the gas phase and aerosol particles is an important source of secondary organic aerosol (SOA). Gas-particle partitioning of organic and inorganic species is influenced by the physical state and water content of aerosols, and therefore ambient relative humidity (RH), as well as temperature and organic loading levels. We introduce a novel combination of the thermodynamic models AIOMFAC (for liquid mixture non-ideality) and EVAPORATION (for pure compound vapor pressures) with oxidation product information from the Master Chemical Mechanism (MCM) for the computation of gas-particle partitioning of organic compounds and water. The presence and impact of a liquid-liquid phase separation in the condensed phase is calculated as a function of variations in relative humidity, organic loading levels, and associated changes in aerosol composition. We show that a complex system of water, ammonium sulfate, and SOA from the ozonolysis of α-pinene exhibits liquid-liquid phase separation over a wide range of relative humidities (simulated from 30% to 99% RH). Since fully coupled phase separation and gas-particle partitioning calculations are computationally expensive, several simplified model approaches are tested with regard to computational costs and accuracy of predictions compared to the benchmark calculation. It is shown that forcing a liquid one-phase aerosol with or without consideration of non-ideal mixing bears the potential for vastly incorrect partitioning predictions. Assuming an ideal mixture leads to substantial overestimation of the particulate organic mass, by more than 100% at RH values of 80% and by more than 200% at RH values of 95%. Moreover, the simplified one-phase cases stress two key points for accurate gas-particle partitioning calculations: (1) non-ideality in the condensed phase needs to be considered and (2) liquid-liquid phase separation is a consequence of considerable deviations from ideal mixing in solutions containing inorganic ions and organics that cannot be ignored. Computationally much more efficient calculations relying on the assumption of a complete organic/electrolyte phase separation below a certain RH successfully reproduce gas-particle partitioning in systems in which the average oxygen-to-carbon (O:C) ratio is lower than ~0.6, as in the case of α-pinene SOA, and bear the potential for implementation in atmospheric chemical transport models and chemistry-climate models. A full equilibrium calculation is the method of choice for accurate offline (box model) computations, where high computational costs are acceptable. Such a calculation enables the most detailed predictions of phase compositions and provides necessary information on whether assuming a complete organic/electrolyte phase separation is a good approximation for a given aerosol system. Based on the group-contribution concept of AIOMFAC and O:C ratios as a proxy for polarity and hygroscopicity of organic mixtures, the results from the α-pinene system are also discussed from a more general point of view.
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Huang, Xi Guang. "A Computational Algorithm for a Spatial Serial Robot." Advanced Materials Research 217-218 (March 2011): 233–37. http://dx.doi.org/10.4028/www.scientific.net/amr.217-218.233.
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The inverse kinematics of serial robots is a central problem in the automatic control of robot manipulators. The aim of this paper is to obtain a computational algorithm to compute the inverse kinematics problem of a spatial serial robot. We use a series of algebraic and numeric transformations to reduce the problem to a univariate polynomial equation. The results can be directly applied to symbolic calculations and decreased considerably the calculation time.
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KATTNER, URSULA R. "The need for reliable data in computational thermodynamics." High Temperatures-High Pressures 49, no. 1-2 (2020): 31–47. http://dx.doi.org/10.32908/hthp.v49.853.
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Computational methods have become indispensable tools for efficient development and processing of new materials and have led to the new discipline of integrated computational materials engineering (ICME). The CALPHAD (calculation of phase diagrams) method has been identified as one of the pillars of ICME. The CALPHAD method, originally developed to model thermodynamic properties and phase diagrams, uses extrapolation methods for the functions of binary and ternary systems that enable the calculation of the properties of higher-order systems. The CALPHAD functions are built to a large extent on available experimental data for these binary and ternary systems. To ensure reliability of the results from CALPHAD calculations, it is necessary to critically evaluate the experimental data that are being used for developing the CALPHAD functions. This review presents a brief overview of the CALPHAD method and its models, summarizes the data that are needed and the criteria that need to be applied for the evaluation of these data.
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Grubyi, S. V. "Calculation of the Cutting Forces and Torque when Milling with End Mills." Proceedings of Higher Educational Institutions. Маchine Building, no. 10 (727) (November 2020): 26–37. http://dx.doi.org/10.18698/0536-1044-2020-10-26-37.
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This paper presents a computational sequence for calculating the components of the cutting force and torque when milling with carbide end mills. The calculation algorithm includes the transition from the tangential and radial components of the force to the force components in the machine coordinate system. On the helical cutting edge, two parts are highlighted: one on the cylindrical (peripheral) surface and the other one on the arc of the rounded tip of the tooth. These parts of the cutting edge are divided into sections where the calculation is performed, followed by summation of the force components along the axes of the machine co-ordinate system and the moment relative to the axis of the cutter. An analysis of the components of the force and torque depending on the depth of cutting, feed, number of teeth of the cutter, blade wear and radius of the tip rounding is performed. The ratio of forces and moments for various milling conditions of structural carbon steel and aluminum alloys is shown. The developed algorithm is applied in a computational program that can be used to perform operational calculations of forces and torque for various milling conditions. The calculated parameters can be used as technological limiters in optimization problems, as well as for strength calculations of tools, milling equipment, and the selection of components of milling machine drives.
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Zuo, Jing, Sui Peng, Yan Yang, Zuohong Li, Zhengmin Zuo, Hao Yu, and Yong Lin. "A Modified Multiparameter Linear Programming Method for Efficient Power System Reliability Assessment." Processes 10, no. 11 (October 25, 2022): 2188. http://dx.doi.org/10.3390/pr10112188.
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Power systems face adequacy risks because of the high integration of renewable energy. It is urgent to develop efficient methods for power system operational reliability assessment. Conventional power system reliability assessment methods cannot achieve real-time assessment of system risk because of the high computational complexity and long calculation time. The high computational complexity is mainly caused by a large number of optimal power flow (OPF) calculations. To reduce the computational complexity, this paper transfers the optimal power flow model as a multiparameter linear programming model. Then, the optimal power flow can be obtained by linear calculations. Furthermore, this paper proposes a state reduction method considering the importance index of transmission lines for further improving the calculation efficiency. Case studies are carried out on IEEE standard systems and a provincial power grid in China. Compared with the conventional reliability assessment method, the reliability assessment efficiency of the proposed method increases by 10–40 times, and the assessment error is less than 1%.
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Nesterenko, A., G. Stolpovskiy, and M. Nesterenko. "Method of Calculation Flexural Stiffness Over Natural Oscillations Frequencies." Archives of Civil Engineering 64, no. 4 (December 1, 2018): 89–103. http://dx.doi.org/10.2478/ace-2018-0046.
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AbstractThe actual load-bearing capacity of elements of a building system can be calculated by dynamic parameters, in particular by resonant frequency and compliance. The prerequisites for solving such a problem by the finite element method (FEM) are presented in the article. First, modern vibration tests demonstrate high accuracy in determination of these parameters, which reflects reliability of the diagnosis. Secondly, most modern computational complexes do not include a functional for calculating the load-bearing capacity of an element according to the input values of resonance frequencies. Thirdly, FEM is the basis for development of software tools for automating the computation process. The article presents the method for calculating flexural stiffness and moment of inertia of a beam construction system by its own frequencies. The method includes calculation algorithm realizing the finite element method.
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Raček, Tomáš, Ondřej Schindler, Dominik Toušek, Vladimír Horský, Karel Berka, Jaroslav Koča, and Radka Svobodová. "Atomic Charge Calculator II: web-based tool for the calculation of partial atomic charges." Nucleic Acids Research 48, W1 (May 13, 2020): W591—W596. http://dx.doi.org/10.1093/nar/gkaa367.
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Abstract Partial atomic charges serve as a simple model for the electrostatic distribution of a molecule that drives its interactions with its surroundings. Since partial atomic charges are frequently used in computational chemistry, chemoinformatics and bioinformatics, many computational approaches for calculating them have been introduced. The most applicable are fast and reasonably accurate empirical charge calculation approaches. Here, we introduce Atomic Charge Calculator II (ACC II), a web application that enables the calculation of partial atomic charges via all the main empirical approaches and for all types of molecules. ACC II implements 17 empirical charge calculation methods, including the highly cited (QEq, EEM), the recently published (EQeq, EQeq+C), and the old but still often used (PEOE). ACC II enables the fast calculation of charges even for large macromolecular structures. The web server also offers charge visualization, courtesy of the powerful LiteMol viewer. The calculation setup of ACC II is very straightforward and enables the quick calculation of high-quality partial charges. The application is available at https://acc2.ncbr.muni.cz.
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McClung, R. Craig, Michael P. Enright, Jonathan P. Moody, Yi Der Lee, and John McFarland. "Integrating Fatigue Crack Growth into Reliability Analysis and Computational Materials Design." Advanced Materials Research 891-892 (March 2014): 1009–14. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.1009.
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Recently a new methodology was developed for automated fatigue crack growth (FCG) life analysis of components based on finite element stress models, weight function stress intensity factor solutions, and algorithms to define idealized fracture geometry models. This paper describes how the new methodology is being used to integrate FCG analysis into highly automated design assessments of component life and reliability. In one application, the FCG model automation is supporting automated calculation of fracture risk due to inherent material anomalies that can occur anywhere in the volume of the component. Automated schemes were developed to divide the component into a computationally optimum number of sub-volumes with similar life and risk values to determine total component reliability accurately and efficiently. In another application, the FCG model automation is supporting integration of FCG life calculations with manufacturing process simulation to perform integrated computational materials engineering. Calculation of full-field, location-specific residual stresses or microstructure is being linked directly with automated life analysis to determine the impact of manufacturing parameters on component reliability.
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Jingjing, Ling, Li Ruiqin, and Zhang Qisheng. "Flexibility Calculation of Like-U Type Flexure Hinge." Open Mechanical Engineering Journal 9, no. 1 (September 10, 2015): 532–39. http://dx.doi.org/10.2174/1874155x01509010532.
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A new like-U type flexure hinge structure is proposed, based on Castigliano’s second theorem and calculus theory. Taking the centrifugal angle parameters as the integration variable, and defining the intermediate parameters, it deduces the analytic computational formula for the like-U type flexure hinge flexibility. By changing the structural parameter of the flexure hinge, it is able to transform four different structure flexure hinges, and the deduced analytic computation formula can be applied to all of these four structures flexure hinges. After the twelve flexure hinges of different structures have been analyzed by applying finite-element method, it is found that the results are in good agreement with the results of analytic computation formula. Thus, the validity of the analytic computation formula is verified, realize accurate design and computation for such flexure hinges is realized, and the theoretical base for technical application of like-U type flexure hinge is provided.
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Liu, Yanli, Hongtao Wu, Yuxuan Yang, Shangyuan Zou, Xuexiang Zhang, and Yaoyao Wang. "Symmetrical Workspace of 6-UPS Parallel Robot Using Tilt and Torsion Angles." Mathematical Problems in Engineering 2018 (June 21, 2018): 1–10. http://dx.doi.org/10.1155/2018/6412030.
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For the fast and efficient closed-loop real-time feedback control of 6-UPS parallel robot (6-UPS), a novel high efficiency calculation of the workspace is proposed and investigated. As a typical Nearly General Platform (NGP), 6-UPS has good symmetries. The symmetries effectively reduce computational cost and improve computational efficiency in the kinematics, singularity, dynamics, and optimization. To scrupulously demonstrate the symmetries of workspace, a novel algorithm is proposed. The modified Euler angles (T&T angles) are employed to represent the orientation matrix of 6-UPS, the inverse kinematics is analyzed, and the workspace of 6-UPS is obtained using the discretization algorithm. Meanwhile, the symmetries of the total orientation workspace are also proved. Compared with the traditional methods, the total orientation workspace reduces 5/6 computation cost, which means that the corresponding computation efficiency is increased by 6 times. Through theoretical and numerical calculations, the symmetries of the total orientation workspace of 6-UPS are verified. The proof of the symmetries lays a solid foundation for improving the computational efficiency of kinematics, dynamics, and control of 6-UPS.
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Forouzesh, Negin, and Nikita Mishra. "An Effective MM/GBSA Protocol for Absolute Binding Free Energy Calculations: A Case Study on SARS-CoV-2 Spike Protein and the Human ACE2 Receptor." Molecules 26, no. 8 (April 20, 2021): 2383. http://dx.doi.org/10.3390/molecules26082383.
Full textAbstract:
The binding free energy calculation of protein–ligand complexes is necessary for research into virus–host interactions and the relevant applications in drug discovery. However, many current computational methods of such calculations are either inefficient or inaccurate in practice. Utilizing implicit solvent models in the molecular mechanics generalized Born surface area (MM/GBSA) framework allows for efficient calculations without significant loss of accuracy. Here, GBNSR6, a new flavor of the generalized Born model, is employed in the MM/GBSA framework for measuring the binding affinity between SARS-CoV-2 spike protein and the human ACE2 receptor. A computational protocol is developed based on the widely studied Ras–Raf complex, which has similar binding free energy to SARS-CoV-2/ACE2. Two options for representing the dielectric boundary of the complexes are evaluated: one based on the standard Bondi radii and the other based on a newly developed set of atomic radii (OPT1), optimized specifically for protein–ligand binding. Predictions based on the two radii sets provide upper and lower bounds on the experimental references: −14.7(ΔGbindBondi)<−10.6(ΔGbindExp.)<−4.1(ΔGbindOPT1) kcal/mol. The consensus estimates of the two bounds show quantitative agreement with the experiment values. This work also presents a novel truncation method and computational strategies for efficient entropy calculations with normal mode analysis. Interestingly, it is observed that a significant decrease in the number of snapshots does not affect the accuracy of entropy calculation, while it does lower computation time appreciably. The proposed MM/GBSA protocol can be used to study the binding mechanism of new variants of SARS-CoV-2, as well as other relevant structures.
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Deng, Rui, De Bo Huang, Guang Li Zhou, Hua Wei Sun, Liang Chang, and Chao Ma. "Research on Mesh Generation Effecting Resistance Calculation." Applied Mechanics and Materials 138-139 (November 2011): 886–93. http://dx.doi.org/10.4028/www.scientific.net/amm.138-139.886.
Full textAbstract:
In order to give consistent and agreeable results in resistance and other hydrodynamic performance with some of the viscous Computational Fluid Dynamics methods which appear to have difficulties when applied to hulls, the investigation of the influential factors like mesh generation which affect the calculation results are taken by the simulation of different cases in the present paper. Through calculation and analysis, specifically with the CFD code FLUENT, an alternative set of computation parameters of mesh generation for engineering application is suggested. The application of the suggestion to the hull researched in this paper result in better agreements with corresponding model tests.