检索结果-内蒙古大学图书馆

INTEGRATOR DESIGN FOR A DIFFERENTIAL ANALYZER

RADIO AND ELECTRONIC ENGINEER 1976年第12期46卷 593-604页

作者： FORSYTHE, W HOUSEMAN, SL LOUGHBOROUGH UNIV TECHNOL DEPT ELECTR & ELECT ENGN LOUGHBOROUGH LE11 3TU LEICESTERSHIRE ENGLAND

The paper sets out to examine various integration algorithms, suitable for implementation in the form of serial binary arithmetic, and concludes that only first-order integration is practicable at the present time and that only first-order prediction is necessary or *** examination is made of the errors inherent in digitizing the main functions of the traditional analogue computer (integration, multiplication, division) and some conclusions reached about the feasibility of building a digital differential analyser given the current state of technology.

关键词： errors integration digital differential analysers first order integration multiplication first order prediction serial arithmetic digital analogue computer digital differential analyser integration algorithms digitizing division total transmission analogue computer Numerical integration and differentiation increment transmission

来源：评论

学校读者我要写书评

暂无评论

A new explicit predictor-multicorrector high-order accurate method for linear elastodynamics

引用

JOURNAL OF SOUND AND VIBRATION 2008年第1-2期310卷 217-229页

作者： Idesman, An. Schmidt, M. Sierakowski, R. L. Texas Tech Univ Dept Mech Engn Lubbock TX 79409 USA USAF Munitious Directorate Eglin AFB FL 32542 USA

A new explicit predictor-multicorrector high-order accurate method is suggested for linear elastodynamics. The method is derived from the implicit high-order accurate method based on the time-continuous Galerkin method proposed earlier in our papers. The basic unknowns for the method are displacements and velocities;accelerations are not calculated. The explicit method uses a predictor-multicorrector technique with one or two passes in order to reach the fourth order of accuracy and has controllable numerical dissipation for the suppression of spurious high-frequency oscillations. In contrast to recently suggested explicit high-order accurate methods based on the time-discontinuous Galerkin method, the new method is more accurate (has a higher order of accuracy) and has better algorithmic properties (e.g., a higher-stability limit) at the same computational efforts. Presented numerical examples show the performance of the new method. The method appears to be competitive for medium- and long-term analysis when accuracy of numerical solutions arises an issue due to error accumulation. (c) 2007 Elsevier Ltd. All rights reserved.

关键词： DISCONTINUOUS GALERKIN METHODS SINGLE STEP algorithms FINITE-ELEMENT METHODS integration algorithms NONLINEAR DYNAMICS UNIFIED SET TIME Explicit high frequency oscillation Nonlinear Dynamics Galerkin method higher-order elastodynamics Finite element method

来源：评论

学校读者我要写书评

暂无评论

Efficient recursive Adams-Bashforth methods in molecular dynamics simulations of N-body systems interacting through pairwise potentials

引用

MOLECULAR SIMULATION 2020年第16期46卷 1248-1254页

作者： Marti, Jordi Diaz, Bernat Tech Univ Catalonia Barcelona Tech Dept Phys Barcelona Spain Tech Univ Catalonia Barcelona Tech Fac Comp Sci Barcelona Spain

A recursive multistep Adams-Bashforth method applied to the Molecular Dynamics simulations of N-body systems interacting through pairwise force fields is introduced and analysed. Equations of motion are obtained using a set of Cartesian coordinates solved by means of an Adams-Bashforth numerical integration scheme of orders, which requires the iterative computation of function time derivatives. The proposed algorithm has been implemented using a programming approach that makes it possible to re-use a source code resulting in small codes, easy to maintain. Practical examples and benchmarks that illustrate the performance of these implementations are included. The study of its performance gives clues to evaluate its efficiency and precision. Numerical tests for a N-particle system are made on the equilibrium configuration of liquid argon near its triple point at 86.5 K and 0.021 angstrom(-3). In most cases, the algorithms here presented outperform those implemented traditionally as the Gear corrector-predictor or the Verlet family, leading to important savings in terms of total computation times and significantly increasing the numerical precision obtained with standard algorithms.

关键词： Recursive formulation Adams-Bashforth methods integration algorithms molecular dynamics

来源：评论

学校读者我要写书评

暂无评论

Accelerating finite-rate chemical kinetics with coprocessors: Comparing vectorization methods on GPUs, MICs, and CPUs

引用

COMPUTER PHYSICS COMMUNICATIONS 2018年 226卷 18-29页

作者： Stone, Christopher P. Alferman, Andrew T. Niemeyer, Kyle E. Computat Sci & Engn LLC Athens GA 30605 USA Oregon State Univ Sch Mech Ind & Mfg Engn Corvallis OR 97331 USA

Accurate and efficient methods for solving stiff ordinary differential equations (ODES) are a critical component of turbulent combustion simulations with finite-rate chemistry. The ODEs governing the chemical kinetics at each mesh point are decoupled by operator-splitting allowing each to be solved concurrently. An efficient ODE solver must then take into account the available thread and instruction level parallelism of the underlying hardware, especially on many-core coprocessors, as well as the numerical efficiency. A stiff Rosenbrock and a nonstiff Runge-Kutta ODE solver are both implemented using the single instruction, multiple thread (SIMT) and single instruction, multiple data (SIMD) paradigms within OpenCL. Both methods solve multiple ODEs concurrently within the same instruction stream. The performance of these parallel implementations was measured on three chemical kinetic models of increasing size across several multicore and many-core platforms. Two separate benchmarks were conducted to clearly determine any performance advantage offered by either method. The first benchmark measured the run-time of evaluating the right-hand-side source terms in parallel and the second benchmark integrated a series of constant-pressure, homogeneous reactors using the Rosenbrock and Runge-Kutta solvers. The right-hand-side evaluations with SIMD parallelism on the host multicore Xeon CPU and many-core Xeon Phi co-processor performed approximately three times faster than the baseline multithreaded C++ code. The SIMT parallel model on the host and Phi was 13%-35% slower than the baseline while the SIMT model on the NVIDIA Kepler GPU provided approximately the same performance as the SIMD model on the Phi. The runtimes for both ODE solvers decreased significantly with the SIMD implementations on the host CPU (2.5-2.7x) and Xeon Phi coprocessor (4.7-4.9x) compared to the baseline parallel code. The SIMT implementations on the GPU ran 1.5-1.6 times faster than the baseline mult

关键词： Chemical kinetics integration algorithms Stiff ODEs SIMD GPU

来源：评论

学校读者我要写书评

暂无评论

An explicit formulation for multiscale modeling of bcc metals

引用

INTERNATIONAL JOURNAL OF PLASTICITY 2008年第12期24卷 2173-2191页

作者： Kuchnicki, S. N. Radovitzky, R. A. Cuitino, A. M. York Coll Penn Dept Phys Sci York PA 17405 USA MIT Dept Aeronaut & Astronaut Cambridge MA 02139 USA Rutgers State Univ Dept Mech & Aerosp Engn Piscataway NJ 08854 USA

Many materials for specialized applications exhibit a body-centered cubic structure;e.g., tantalum, vanadium, barium and chromium. In addition, the successful modeling of body-centered cubic (bcc) metals is a necessary step toward modeling of common structural materials such as iron. Implicit formulations for this class of materials exist [e.g., Stainier, L, Cuitino, A., Ortiz, M.. 2002. A micromechanical model of hardening, rate sensitivity, and thermal softening in bcc crystals. journal of the Mechanics and Physics of Solids 50 (7), 1511-1545;Kuchnicki, S., Radovitzky, R., Cuitino, A., Strachan, A., Ortiz, M., 2007. A pressure-dependent multiscale model for bcc metals], but are impractical to resolve large-scale dynamic deformation processes. In this article, we describe a procedure analogous to Kuchnicki et al. [Kuchnicki, S.. Cuitino, A., Radovitzky, R., 2006. Efficient and robust constitutive integrators for single-crystal plasticity modeling. International journal of Plasticity 22 (10),1988-2011]. wherein we construct an explicit formulation for the multiscale physics models. This update is based on the model of Kuchnicki et al. (in preparation) using a power law representation for the plastic slip rates. The existing implicit form of the model provides qualitative matching with experiments at quasi-static strain rates. The model is recast in an explicit form and applied first to a high quasi-static strain rate to verify that the two forms of the model return similar predictions for similar input parameters. The explicit model is also applied to several high strain rates, showing that it captures characteristic features observed in experimental tests of high-rate deformations, such as the drop in stress immediately after yield that is present in split Hopkinson pressure bar (SHPB) experiments. This test provides qualitative evidence that the model is suitable for high-strain-rate applications. The utility of the model is further demonstrated by a one-dimension

关键词： Crystal plasticity Explicit integration integration algorithms Dynamic deformation

来源：评论

学校读者我要写书评

暂无评论

Explicit solitons in the parabolic law nonlinear negative-index materials

引用

NONLINEAR DYNAMICS 2017年第1期88卷 595-607页

作者： Sonmezoglu, Abdullah Yao, Min Ekici, Mehmet Mirzazadeh, Mohammad Zhou, Qin Bozok Univ Dept Math Fac Sci & Arts TR-66100 Yozgat Turkey Wuhan Donghu Univ Sch Elect & Informat Engn Wuhan 430212 Peoples R China Univ Guilan Dept Engn Sci Fac Engn & Technol Rudsar Vajargah *** Iran

This paper deals with the existence of explicit ultra-short solitons in the negative-index materials with third-order dispersion and higher-order nonlinearities. Four integration algorithms, that are the improved modified extended tanh-function method, the extended trial equation method, the extended Jacobi elliptic function expansion method and the -expansion method, are employed to extract analytical traveling wave solutions. The presented results show that exact solitons can exist in this physical model.

关键词： Solitons Negative-index materials integration algorithms Traveling wave solutions

来源：评论

学校读者我要写书评

暂无评论

Efficient and robust constitutive integrators for single-crystal plasticity modeling

引用

INTERNATIONAL JOURNAL OF PLASTICITY 2006年第10期22卷 1988-2011页

作者： Kuchnicki, S. N. Cuitino, A. M. Radovitzky, R. A. Rutgers State Univ Dept Mech & Aerosp Engn Piscataway NJ 08854 USA MIT Dept Aeronaut & Astronaut Cambridge MA 02139 USA

Small-scale deformation phenomena such as subgrain formation, development of texture, and grain boundary sliding require simulations with a high degree of spatial resolution. When we consider finite-element simulation of metal deformation, this equates to thousands or hundreds of thousands of finite elements. Simulations of the dynamic deformations of metal samples require elastic-plastic constitutive updates of the material behavior to be performed over a small time step between updates, as dictated by the Courant condition. Further, numerical integration of physically-based equations is inherently sensitive to the step in time taken;they return different predictions as the time step is reduced, eventually approaching a stationary solution. Depending on the deformation conditions, this converged time step becomes short (10(-9) s or less). If an implicit constitutive update is applied to this class of simulation, the benefit of the implicit update (i.e., the ability to evaluate over a relatively large time step) is negated, and the integration is prohibitively slow. The present work recasts an implicit update algorithm into an explicit form, for which each update step is five to six times faster, and the compute time required for a plastic update approaches that needed for a fully-elastic update. For dynamic loading conditions, the explicit model is found to perform an entire simulation up to 50 times faster than the implicit model. The performance of the explicit model is enhanced by adding a subcycling algorithm to the explicit model, by which the maximum time step between constitutive updates is increased an order of magnitude. These model improvements do not significantly change the predictions of the model from the implicit form, and provide overall computation times significantly faster than the implicit form over finite-element meshes. These modifications are also applied to polycrystals via Taylor averaging, where we also see improved model performance. (c)

关键词： crystal plasticity explicit integration integration algorithms dynamic deformation

来源：评论

学校读者我要写书评

暂无评论

Consistent linearization for the: Exact stress update of Prandtl-Reuss non-hardening elastoplastic models

引用

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING 1996年第7期39卷 1219-1235页

作者： Wei, Z Peric, D Owen, DRJ Department of Civil Engineering University College of Swansea Swansea SA2 8PP Wales U.K.

This paper presents a consistent algorithm, which combines the advantages of the exact time integration of Prandtl-Reuss elastoplastic models and the quadratic asymptotic convergence of Newton-Raphson iteration strategies. The consistent modulus is evaluated by a full linearization of the exact stress update procedure. Numerical tests for a thin wall tube subjected-to combined loads of tension and torsion are performed to illustrate the accuracy and efficiency of the consistently linearized exact stress update algorithm described in the paper. For comparison purpose numerical results of the radial return method are also given.

关键词： plasticity numerical integration algorithms consistent linearization finite elements

来源：评论

学校读者我要写书评

暂无评论

CONTINUOUS SIMULATION OF A COMPLEX QUEUING SYSTEM

引用

SIMULATION 1977年第2期29卷 42-48页

作者： LAM, CF PEDERSEN, J MED UNIV S CAROLINA DEPT BIOMETRYCHARLESTONSC 29401 USDA FOREST SERVFORESTRY SCI LABSE FOREST EXPT STNRES TRIANGLE PKNC 27709

This paper deals with the continuous simulation of complex queuing systems on a digital computer. Con tinuous-system mathematical models of multicompart ment queuing systems based on a birth-death process consist of large sets of differential equations. A dynamic allocation algorithm can substantially de crease the required computer time and storage by con tinuously adjusting the size of the system of differ ential equations. The applicability of the continuous approach to simulation of complex queuing systems is demonstrated for a four-compartment outpatient clinic.

关键词： algorithm to avoid solving unneeded equa tions in a multicompartment simulation integration algorithms multicompartment continuous simulation simulating a clinic transients in a queuing system

来源：评论

学校读者我要写书评

暂无评论

Performance of explicit substepping integration scheme for complex constitutive models in finite element analysis

引用

COMPUTERS AND GEOTECHNICS 2023年第1期162卷

作者： Dong, Yuepeng Tech Univ Denmark Dept Environm & Resource Engn DK-2800 Lyngby Denmark

Advanced constitutive models for soils are critical to achieve reliable results in geotechnical analyses, but their implementation in finite element programs should be accurate, efficient, and robust. This paper describes the algorithm used to integrate a complex elastoplastic constitutive model for clays, the MIT-E3, in the finite element framework, followed by extensive evaluations. The explicit substepping scheme with different order of accuracy is adopted in the integration due to its simplicity, and also because of complexities in the model formulation. Several important issues are highlighted in the integration to improve the model performance in the analysis, (i) rigorous update of the void ratio, (ii) efficient intersection with the bounding surface, (iii) consistent correction of the drifted stress to the bounding surface, and (iv) consistently linearized tangent operator in the explicit substepping scheme. The numerical integration is verified by reproducing the stress-strain behaviour in single element tests, and also by checking the error behaviour with the order of accuracy of the integration method. The accuracy and efficiency of different methods in the integration are evaluated in a rigorous and consistent manner, which has practical implications for choosing suitable methods and parameters in the analysis. Good convergence rate can be achieved using the proposed consistently linearized tangent operator. The substepping scheme with error control is shown to be stable in the challenging geotechnical problems, while the efficiency is affected by the strain increment size which is problem dependent.

关键词： Constitutive models Finite element method integration algorithms Accuracy and efficiency

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：