A continuation‐based task programming model for C++: design of the Causeway library

There is a big class of problems that requires writing programs in an asynchronous manner. Cloud computing, service‐oriented architectures, multi‐core and heterogeneous systems all require programs to be written with asynchronous components. The necessity of concurrency and asynchronous execution brings in the added complexity of the inversion of control into the system, either through message passing or through event processing. In this paper, we introduce explicit programming language support for asynchronous programming that completely hides inversion of control. The presented programming model defines a common abstraction of the different types of tasks, both synchronous and asynchronous. It defines common imperative control constructs equivalent to those of the host programming language, along with a few more advanced ones for transactional and parallel execution that can universally work for any task type. It allows the programmer to implement the logic of an asynchronous system in a natural way by writing simple, seemingly, synchronous imperative code. We will show that the programs written using this approach are easier to understand by programmers. They are also easier to design automated tests for, and for performing computer‐based static analysis of the program logic. The principles behind this approach were tested in a couple of real‐world systems with worldwide user base. Our experience shows that it makes the complex code with a lot of interdependencies between asynchronously executed tasks easy to write and reason about. Copyright © 2016 John Wiley & Sons, Ltd.     

带控制截面机翼结构基于非线性能量阱的颤振抑制

二元刚性机翼结构简化为三自由度结构,在浮沉位移和俯仰位移方向的非线性刚度简化为立方非线性,对于控制截面存在间隙采用双线性刚度代替.基于靶能量转移的原理在机翼结构耦合非线性能量阱,实现对机翼颤振的抑制.考虑准定常气流,建立机翼减振前后的运动方程,通过数值模拟构造减振前后峰值-峰值图,初步反应其整体的减振效果.通过弧长数值连续法和结合Floquet算子构造减振前后的分岔图,并研究其稳定性.通过分岔图结合数值模拟的峰值图,讨论在不同风速下的减振效果,结果表明机翼结构颤振可以部分甚至全部抑制.     

A wavelet regularization method for solving numerical analytic continuation

In this paper we consider the problem of analytic continuation of analytic function on a strip domain, where the data are given only on the real axis. This is an ill-posed problem. The occurrence of its ill-posedness is intrinsically due to the high-frequency perturbation of data. However, Meyer wavelet has compact support in the frequency space. By expanding the data and the solution in a basis of Meyer wavelets, high-frequency components can be filtered away, and the Hölder-type stability estimates for both a priori and a posteriori choice rules are obtained. Numerical illustrations show that the method works effectively.     

一种基于自适应步长控制与组合参数化的改进连续潮流计算方法

提出了一种可以完全跟踪光伏(PV)曲线斜率变化的自适应变步长算法,并在理论上比较分析了所提变步长法与常规变步长法的灵敏度特性,通过分析发现,所提变步长法具有更优的自适应性,在保证连续潮流计算精度的同时,大幅降低了计算时间。提出了一种组合参数化法,即在PV曲线的不同区域采用不同的参数化法,同时在PV曲线追踪过程中设置参数化切换断点,并以校正不收敛作为组合切换判据。基于IEEE标准节点系统的计算结果验证了所提自适应变步长算法与组合参数化法的有效性与优越性。     

具有时滞的二阶微分方程边值问题解的存在性

研究了一类具有时滞的二阶微分方程三点共振边值问题,利用Mawhin连续性定理获得了该边值问题解的存在性的充分条件,得到了一些新的结果.     

Chern numbers of smooth varieties via homotopy continuation and intersection theory

Homotopy continuation provides a numerical tool for computing the equivalence of a smooth variety in an intersection product. Intersection theory provides a theoretical tool for relating the equivalence of a smooth variety in an intersection product to the degrees of the Chern classes of the variety. A combination of these tools leads to a numerical method for computing the degrees of Chern classes of smooth projective varieties in Pⁿ. We illustrate the approach through several worked examples.     

同伦迭代法及应用于一般6-SPS并联机器人机构正位置问题

提出了一种基于同伦函数的新迭代法，它不需选取初值并可求出全部解，比传统的同伦（连续）法简化了求解过程，提高了计算效率和可靠性。将该方法应用于求解一般６－ＳＰＳ机械手的正位置问题，得到满意的结果，较方便地求出了问题的全部４０组解     

基于同伦摄动的同伦算法及其在机构学中的应用

根据同伦摄动的思想，改进预估校正计算公式，从而提出了同伦摄动的同伦算法，该法有效地避免了现有路径跟踪方程在求解亏欠方程组时易出现的漏解现象，并有效地提高了计算效率，从而保证了同伦算法的有效应用。并将该算法应用于求解机构学问题的亏欠方程组，取得了满意的效果。     

A continuation method for rigid‐cohesive fracture in a discontinuous Galerkin finite element setting

An energy minimization formulation of initially rigid cohesive fracture is introduced within a discontinuous Galerkin finite element setting with Nitsche flux. The finite element discretization is directly applied to an energy functional, whose term representing the energy stored in the interfaces is nondifferentiable at the origin. Unlike finite element implementations of extrinsic cohesive models that do not operate directly on the energy potential, activation of interfaces happens automatically when a certain level of stress encoded in the interface potential is reached. Thus, numerical issues associated with an external activation criterion observed in the previous literature are effectively avoided. Use of the Nitsche flux avoids the introduction of Lagrange multipliers as additional unknowns. Implicit time stepping is performed using the Newmark scheme, for which a dynamic potential is developed to properly incorporate momentum. A continuation strategy is employed for the treatment of nondifferentiability and the resulting sequence of smooth nonconvex problems is solved using the trust region minimization algorithm. Robustness of the proposed method and its capabilities in modeling quasistatic and dynamic problems are shown through several numerical examples.     

航磁寻找油气藏几种方法应用效果分析

航磁异常与油气藏之间有着密切的关系 ,烃类向上逸散及局部构造在磁异常中都有不同程度的表现 ,由此可以建立航磁异常与烃类分布关系的理论模式。文中探讨了 3种提取与油气相关异常的方法 ,即用剖面上延剩余法提取与烃类相关的高频微磁异常及与局部构造有关的中频局部异常 ;用归一化总梯度法确定油气上方场源位置 ;用线积分法圈定油气田范围等 ,并结合实例对以上方法的应用效果进行了分析