High-accuracy quadrature methods for solving boundary integral equations of steady-state anisotropic heat conduction problems with Dirichlet conditions

This paper presents the mechanical quadrature methods (MQMs) for solving the boundary integral equations of steady-state anisotropic heat conduction equation on the smooth domains and polygons, respectively. The costless and high-accurate Sidi–Israeli quadrature formula are applied to deal with the integrals in which the kernels have a logarithmic singularity. Especially, the Sidi transformation is used for the polygon cases in order to obtain a rapid convergence by degrading the singularity at the corners on the boundary. The convergence and stability of the MQMs solution are proved based on Anselone's collective compact theory. In addition, asymptotic error expansion of the MQMs shows that the approximation order is of O(h³), where h is the partition size of the boundary. Finally, numerical examples are tested and results verify the theoretical analysis.     

关于《求解LP问题的部分基变量算法》的勘误及补正

文章针对周康等人的《求解LP问题的部分基变量算法》一文进行了分析,指出其文中算法原理及算法步骤存在的一些错误,补正了算法的不完善之处,并通过数值试验验证算法的计算性能。     

水工混凝土结构裂缝成因挖掘的粗集方法研究

裂缝是水工混凝土结构常见病害之一,针对水工混凝土结构运行期的裂缝问题,应用粗集理论,结合实测资料,对裂缝产生的主要原因进行了系统地研究,提出了裂缝成因挖掘的粗集方法.     

Formation of CaO-TiO2-MgO-Al2O3 dual phase inclusion in Ti stabilized stainless steel

The formation of CaO-TiO2-MgO-Al2O3 dual phase inclusion in 321 stainless steel was investigated in the laboratory. The result indicated that the condition for the formation of CaO-TiO2-MgO-Al2O3 in 321 steel is [Ca]〉0.001wt%, [Ti]〉0.1wt%, and [A1]〉0.01wt%. The mechanism is the following： Al2O3 inclusion turns into CaO-Al2O3 after Ca-Si wire is fed into the molten steel; [Mg] is then obtained by reducing MgO in slag or crucible wall by [Al] and [Ti]; finally CaO-Al2O3 inclusion is changed into CaO-TiO2-MgO-Al2O3 by the reaction with [Mg], [Ti], and [O] in the molten steel simultaneously.     

Flume Experiment on Stream Blockage by the Debris Flow From Tributary

Stream blockage by the debris flow from tributary valleys is a common phenomenon in mountainous area,which takes place when large quantities of sediment transported by debris flow reaches a river channel causing its complete or partial blockage.The dam formed by debris flow may causes upstream and downstream flooding,and presents great threat to people and property.Because of the catastrophic influence on people and property,debris-flow dam has attracted many attentions from the researchers and local administration.But,lit- tle attention has been given to the quantitative interrelationships of the potential influential factors.In this pa- per,the interrelationships of important influential factors caused the stream blockage by debris flow were ana- lyzed through flume experiment,and a model to predict the blockage was presented.     

Analysis of a Gyroscope＇s Rotor Nonlinear Supported Magnetic Field Based on the B-Spline Wavelet-FEM

A supported framework of a gyroscope＇s rotor is designed and the B-Spline wavelet finite element model of nonlinear supported magnetic field is worked out. A new finite element space is studied in which the scaling function of the B-spline wavelet is considered as the shape function of a tetrahedton. The magnetic field is spited by an artificial absorbing body which used the condition of field radiating, so the solution is unique. The resolution is improved via the varying gradient of the B-spline function under the condition of unchanging gridding. So there are some advantages in dealing with the focus flux and a high varying gradient result from a nonlinear magnetic field. The result is more practical. Plots of flux and in the space is studied via simulating the supported system model. The results of the study are useful in the research of the supported magnetic system for the gyroscope rotor.     

固支简支端部边界条件下同轴圆柱壳体的流致不稳定性研究

基于Paiedoussis等同轴圆柱壳体流致不稳定性的数学模型和研究方法，分析了固支－简支端部约束条件下同轴圆柱壳体系统的流致不稳定性，结果表明：同两端固支相比，固支－简支端部边界下壳体系统的失稳临界流速更低。     

联合回归估计的优良性

讨论了联合回归估计的性质，证明了它是最小二乘估计的压缩估计，且有比它更好的抗干扰性和稳健性。     

1Cr17Ni2 钢锻造工艺试验

通过对１Ｃｒ１７Ｎｉ２钢锻造工艺试验，掌握了锻件成形后的组织和力学性能，找出了锻件形成过程中使锻件各质点处于最佳应力状态的锻造工艺方法，避免锻造裂纹