Cost-effective modeling strategies for the analysis of spliced steel connections

The paper presents several cost-effective modeling strategies that can be used by structural engineers in practice to determine the stresses in the spliced members. The computational efficiency and the modeling effort required for the several modeling options are also discussed. The deformation mechanisms and load transfer for several types of connections are illustrated. Optimization techniques are also presented to economize the computer time for connections with large number of bolts. Results are presented to compare the accuracy of several modeling strategies commonly used in practice. It is shown that for eccentric connections, the flexural bending largely affect the maximum tensile and compressive stresses within the joint. The difference may reach up to 54%. Finally, Experimental comparisons are made with the numerical procedures for typical connection model.     

Effect of anisotropic microstructure on magnetic Barkhausen noise in cold rolled low carbon steel

We have measured the orientation and depth dependence of the magnetic Barkhausen noise (MBN) in an industrial pipeline steel sheet. Thin samples were cut out from the sheet cross section at different depths, parallel and transverse to the rolling direction (rolling and transverse samples). The integrated MBN energy has shown no depth dependence for transverse samples. On the other hand, the rolling samples have shown larger MBN noise energy and strong depth dependence.The microstructure of the samples was studied by optical and electron microscopy, parameters related to the shape and the quantity of carbon precipitates and grains were extracted by image processing techniques. The strong depth and orientation dependence of the MBN have been explained by changes of the grain and precipitate microstructure.     

C~n中单位球上的面积积分与BMO

设B是Cn中的单位球,S是Cn中的单位球面,Sα(f)是B上的面积积分.设f∈BMOA, 若存在正测度集E(?)S,使Sα(f)<∞在E上成立,则Sα(f)<∞在S上几乎处处成立,同时 Sα(f)∈ BMO(S)且存在常数C,使得||Sαf||*≤C||f||*.     

Local convergence results of Gauss-Newton's like method in weak conditions

In this paper, we study the convergence of Gauss-Newton's like method for nonlinear least squares problems. Under the hypothesis that derivative satisfies some kind of weak Lipschitz condition, we obtain the sharp estimates of the radii of convergence ball of Gauss-Newton's like method and the uniqueness ball of the solution.     

钒(Ⅴ)-7-碘-8-羟基喹啉-5-磺酸显色体系测定钢样中的钒

研究了7-碘-8-羟基喹啉-5-磺酸（H2QSI）在乙醇存在下分光光度法测定钡（Ⅴ）的最佳条件。在乙醇存在下pH4的硫酸介质中,（H2QSI）与V（Ⅴ）形成了红棕色配合物,最大吸收位于506nm处,表观摩尔吸光系数εmax＝2.9×103L·mol-1·cm-1,有色配合物组成为V（Ⅴ）:（H2QSI）＝1:3。钒（Ⅴ）在0-14μg／25mL符合比耳定律、本法用于钢样中的测定,结果满意。H2QSI是光度分析中的一种显色剂,近年来,8-羟基喹啉类试剂用于钒（Ⅴ）的测定已有报道[1]:,H2QSI曾见用于稀土元素的光度测定[2],但用于钒（Ⅴ）的测定尚未见报道。本文研究了V（Ⅴ）与H2QSI的显色反应条件及组成,在pH4的乙醇介质中,V（Ⅴ）与H2QSI生成红棕色配合物ε506nm＝2.9×103L·mol-1·cm-1。本方法用于低碳合金钢中钒的测定,结果满意。     

单位球上F(p,q,s)空间到Bloch型空间的复合算子

该文分别给出了单位球B上空间F(p, q, s)到空间β^α之复合算子C_{varphi}为有界算子和紧算子的充要条件.同时作为推论获得了Bloch型空间的相应结果.     

A mathematical programming model and solution for scheduling production orders in Shanghai Baoshan Iron and Steel Complex

In this paper, we investigate the production order scheduling problem derived from the production of steel sheets in Shanghai Baoshan Iron and Steel Complex (Baosteel). A deterministic mixed integer programming (MIP) model for scheduling production orders on some critical and bottleneck operations in Baosteel is presented in which practical technological constraints have been considered. The objective is to determine the starting and ending times of production orders on corresponding operations under capacity constraints for minimizing the sum of weighted completion times of all orders. Due to large numbers of variables and constraints in the model, a decomposition solution methodology based on a synergistic combination of Lagrangian relaxation, linear programming and heuristics is developed. Unlike the commonly used method of relaxing capacity constraints, this methodology alternatively relaxes constraints coupling integer variables with continuous variables which are introduced to the objective function by Lagrangian multipliers. The Lagrangian relaxed problem can be decomposed into two sub-problems by separating continuous variables from integer ones. The sub-problem that relates to continuous variables is a linear programming problem which can be solved using standard software package OSL, while the other sub-problem is an integer programming problem which can be solved optimally by further decomposition. The subgradient optimization method is used to update Lagrangian multipliers. A production order scheduling simulation system for Baosteel is developed by embedding the above Lagrangian heuristics. Computational results for problems with up to 100 orders show that the proposed Lagrangian relaxation method is stable and can find good solutions within a reasonable time.     

Boundary Harnack Principle for <Emphasis Type="Italic">p</Emphasis>-harmonic Functions in Smooth Euclidean Domains

We establish a scale-invariant version of the boundary Harnack principle for p-harmonic functions in Euclidean C ^1,1-domains and obtain estimates for the decay rates of positive p-harmonic functions vanishing on a segment of the boundary in terms of the distance to the boundary. We use these estimates to study the behavior of conformal Martin kernel functions and positive p-superharmonic functions near the boundary of the domain. H. A. was partially supported by Grant-in-Aid for (B) (2) (No. 15340046) Japan Society for the Promotion of Science. N. S. was partially supported by NSF grant DMS-0355027. X. Z. was partially supported by the Taft foundation.     

Ball spin generation for oblique impacts with a tennis racket

In this paper, we describe an experimental investigation of the oblique impact between a tennis ball and head clamped tennis racket. It was found that the magnitude of the ball rebound spin was not a function of the material, gage or tension of the string used in the tennis racket. Furthermore, it was concluded that all strings exhibit a sufficiently large friction coefficient that the ball begins to roll during impact. There is anecdotal evidence from tennis players that suggests that a high string tension or a rough string surface enable them to impart more spin to the ball. For example, players have been quoted as saying that a high string tension makes the strings “bite” into the ball, giving more spin. The data reported in this study do not support these observations. Analysis of the experimental data has shown that the balls are rebounding from the surface with more spin than would typically be associated with rolling. A second experiment showed that the balls commenced rolling at the mid-point of the impact. This information was used in a theoretical model to show that the spin that acts on the ball during the impact can be higher than the value of the rolling spin at the end of the impact.     

XPS和AES研究A3钢表面杂多酸钝化膜

通过比较多种杂多酸及铬酸盐等纯化剂的钝化效果，发现Ｈ３ＰＭｏ１２Ｏ４０是一种优良的纯化剂。在５５℃，ｐＨ１．０的条件下，Ａ３钢在２０ｇ／Ｌ的Ｈ３ＰＭｏ１２Ｏ４０溶液中能形成致密的耐蚀性保护膜。ＡＥＳ结合Ａｒ＾＋溅射测得膜的元素组成为：Ｐ１．９％，Ｍｏ１７．９％，Ｏ６９．６％，Ｆｅ１０．７％．ＸＰＳ测得膜中Ｍｏ以Ｍｏ（Ⅵ）、Ｍｏ（Ｖ）ｔ Ｍｏ（Ⅳ）三种氧化态存在。红外及Ｒａｍａｎ光谱表明，膜的主要振