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51.
Maria Laura Martins‐Costa Rogrio M. Saldanha da Gama 《International journal for numerical methods in engineering》2001,52(10):1047-1067
This work studies an unsaturated flow of a Newtonian fluid through a rigid porous matrix, using a mixture theory approach in its modelling. The mixture consists of three overlapping continuous constituents: a solid (porous medium), a liquid (Newtonian fluid) and an inert gas (to account for the mixture compressibility). A set of two nonlinear partial differential equations describes the problem, which is approximated by means of a Glimm's scheme, combined with an operator splitting technique. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
52.
Hongda Wang Jianchun Xing Qiliang Yang Wei Song Xuewei Zhang 《Software Testing, Verification and Reliability》2016,26(2):149-169
Web Service Business Process Execution Language (WS‐BPEL) is one of the most popular service‐oriented workflow applications. The unique features (e.g. dead path elimination semantics and correlation mechanism) of WS‐BPEL applications have raised enormous problems to its test case generation, especially in unit testing. Existing studies mainly assume that each path in the control flow graphs that correspond to WS‐BPEL applications is feasible, which always yields imprecise test cases or complicates testing results. The current study tackles this problem based on satisfiability modulo theory solvers. First, a new coverage criterion is proposed to measure the quality of test sets for testing WS‐BPEL applications. Second, decomposition algorithms are presented to obtain test paths that meet the proposed coverage criterion. Finally, this paper symbolically encodes each test path with several constraints by capturing the unique features of WS‐BPEL. These constraints are solved and the test cases (test paths and test data) are obtained with the help of satisfiability modulo theory solvers to test WS‐BPEL applications effectively. Experiments are conducted using our approach and other typical approaches (e.g. message‐sequence generation‐based approach and concurrent path analysis approach) with 10 WS‐BPEL applications. Experimental results demonstrate that the test cases generated by our approach can avoid instantiating idle instance and expose more faults. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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基于有限体积法及FDS格式的感潮河段二维泥沙冲淤模型 总被引:3,自引:0,他引:3
本文以木兰溪下游裁弯河段为例,建立了有限体积法的水平二维非恒定流均匀沙不平衡输移计算模型。采用黎曼近似解通量差分裂(FDS)格式计算通过各单元边的水流、含沙量法向数值通量,并应用相关的悬移质、推移质河床变形计算公式计算冲淤变化。数值模型经相应的河工模型试验资料率定、检验后,预测了裁弯工程建成后河道可能的冲淤变化,为工程设计和施工提供依据。 相似文献
56.
A new tridiagonal Toeplitz linear system (TTLS) solver is proposed. The solver first decomposes an n-dimensional strictly diagonally dominant TTLS equation into a number of m-dimensional subsystems employing a modified Gaussian elimination method. An analytic solution of a continued fraction is obtained to derive the solver. The solver based on the modified Gaussian elimination method fully exploits parallelism. Computation and communication complexities of the proposed algorithm are all shown to be O(n/m). 相似文献
57.
Erik Abenius Ulf Andersson Fredrik Edelvik Lasse Eriksson Gunnar Ledfelt 《International journal for numerical methods in engineering》2002,53(9):2185-2199
We present a new approach to time domain hybrid schemes for the Maxwell equations. By combining the classical FD‐TD scheme with two unstructured solvers, one explicit finite volume solver and one implicit finite element solver, we achieve a very efficient and flexible second‐order scheme. The second‐order accuracy of the hybrid scheme is verified through convergence studies on perfectly conducting as well as dielectric and diamagnetic circular cylinders. The numerical results also show its superiority to the FD‐TD scheme. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
58.
本文在用连续介质法推导出高层双肢剪力墙结构稳定特征方程的基础上,用常微分方程(简称:ODE──OrdinaryDifferentialEquation)求解器研究该结构的稳定特征值问题。首先,将该特征值问题归结为标准的非线性ODE边值问题;然后用ODE求解器求解这一等价的非线性问题。得到的结果与加权余量法和有限差分法结果进行比较,吻合得很好,表明稳定特征值问题能够凭借ODE求解器的功效得以精确、可靠、方便地求解。 相似文献
59.
L.K. Lundin 《Parallel Computing》1998,24(14):2021-2034
To compute the time-dependent flow of a rotating incompressible fluid we consider the velocity–vorticity formulation of the Navier–Stokes equations in cylindrical coordinates. In the numerical method employed the velocity field at each time-step is found as the least squares solution of an overdetermined system of linear equations, Ax=b. We consider how to compute x using the preconditioned conjugate gradient algorithm for least squares (PCGLS) on a distributed parallel computer. The various aspects of using a parallel computer are discussed, and results for a wide range of parallel computers are presented. The parallel speed-up depends on the architecture but is typically about 80% of the number of processors used. 相似文献
60.
In this paper we propose to use a TVD flux, instead of a first-order monotone flux, as the building block for designing very
high-order methods; we implement the idea in the context of ADER schemes via a new flux expansion. Systematic assessment of
the new schemes shows substantial gains in accuracy; these are particularly evident for problems involving long time evolution 相似文献