A numerical study of pulsatile blood flow in an eccentric catheterized artery using a fast algorithm

The pulsatile blood flow in an eccentric catheterized artery is studied numerically by making use of an extended version of the fast algorithm of Borges and Daripa [J. Comp. Phys., 2001]. The mathematical model involves the usual assumptions that the arterial segment is straight, the arterial wall is rigid and impermeable, blood is an incompressible Newtonian fluid, and the flow is fully developed. The flow rate (flux) is considered as a periodic function of time (prescribed). The axial pressure gradient and velocity distribution in the eccentric catheterized artery are obtained as solutions of the problem. Through the computed results on axial pressure gradient, the increases in mean pressure gradient and frictional resistance in the artery due to catheterization are estimated. These estimates can be used to correct the error involved in the measured pressure gradients using catheters.     

NUMERICAL SIMULATION OF VISCOUS FLOW AROUND AN APPENDED SUBMARINE MODEL

A multizone/multiblock coupled RANS equation solver is presented to numerically simulate the viscous flow around an appended submarine model at Reynolds number 1. E7. k-ε two equation turbulenc model together with wall function are used. The resulting finite difference equations are solved by SIMPLEC, ADI. The technique of rising up the bottom surface is presented to overcome radial contraction problem in Cartesian coordinate system. Benchmark numerical calculations have been compared with experimental data, the radial distribution of axial velocity on the propeller disk plane is 4. 63%.     

Generating effective test cases based on satisfiability modulo theory solvers for service‐oriented workflow applications

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.     

Excel规划求解在地下水资源管理中应用

由一个简单例子介绍了Excel规划求解步骤。通过两个示例介绍了Excel在应用嵌入法和响应矩阵法建立地下水资源管理模型求解中的应用。示例计算表明,Excel作为普及、简易的工具,应用于地下水资源管理线性规划模型求解具有简明、方便实用的特点。     

关于应力波在PHC管桩接头部位反射问题的探讨

针对反射波法检测PHC管桩时经常无法检测到接头板部位反射波的现象,从理论上分析了可能产生该现象的原因,并利用自主开发的＂基桩应力波反射法求解器＂验证了这一现象,最后结合工程实例提出了几点建议。     

基于有限体积法及FDS格式的感潮河段二维泥沙冲淤模型

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。     

A parallel algorithm solving a tridiagonal Toeplitz linear system

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).     

高效的插入式LED阵列驱动接口电路

基于插入技术以及能量回馈策略,提出一种插入式LED阵列驱动接口电路,可高效率地驱动规则及不规则LED阵列。在分析电路工作原理的基础上,推导了其主要关系式。制作并优化了单通道的插入式LED阵列驱动接口电路样机。实验结果表明在全负载范围内实验数据与理论分析值大致吻合,而且样机能实现高效率的LED驱动。     

Hybrid time domain solvers for the Maxwell equations in 2D

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.     

ODE求解器求解高层双肢剪力墙结构稳定特征值问题

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。