基于遗传算法的工作辊温度场参数优化模型

针对热连轧机工作辊热辊形计算中温度场模型的热交换等参数难以确定的问题 ,建立了基于遗传算法的参数优化模型 ,可以解决复杂条件下的热参数的求解问题。利用优化参数计算的轧辊温度场与实际测量结果一致。     

浅析铝带坯热轧机工作辊清刷辊的结构特点及使用工艺

本文阐述了工作辊清刷辊两种类型的结构特点及其使甩工艺，指出了按照合理的使用工艺对热轧生产的重要性。     

Analytical Method for Predicting the Mobility of Slow-Moving Landslides owing to Groundwater Fluctuations

This paper deals with the active landslides that are controlled by pore water pressure changes owing to groundwater fluctuations. These landslides are usually characterized by low displacement rate with deformations essentially concentrated within a narrow shear zone, above which the unstable soil mass moves as a rigid body. Taking advantage of some original analytical solutions, a method is developed for a preliminary prediction of the landslide mobility. This method is based on a simple sliding-block model and allows the landslide velocity to be readily evaluated once pore water pressure measurements are available. An application to a case study documented in the literature is also shown.     

刚架替代框架中框架梁的结构设计

在底层框架上部砖混的建筑结构中,以刚架替代框架中的框架梁,刚架降蔽在砖混墙体内。此结构设计既可以增大建筑空间,又可以满足层高和净空的要求。     

Analytical Framework for the Choice of Dispute Resolution Methods in International Construction Projects Based on Risk Factors

International construction projects provide opportunities for developing countries to advance in the global economy and for international construction and design firms to increase their profit and market share. Despite the attractive opportunities that international construction offers, international contractors are faced with many challenges and difficulties when moving into international markets. Many risks are associated with international construction, whether external or project-specific risks. Those risks affect how contract clauses are written, including the dispute resolution clause. This paper discusses the different dispute resolution methods employed in international construction contracts and develops an analytical framework (DRM-Risk matrix) suggesting the use of specific dispute resolution methods depending on the risks expected in the project. The matrix may eventually help international contractors in the selection of the appropriate dispute resolution method during contract formation depending on the risks involved in a project.     

An Approach for Predicting the Composition of a Recycled Al-Alloy

The present paper describes a method for predicting the imminence (hereafter referred to as ‘quality’) of the chemical composition of a recycled alloy to that of a standard alloy of aluminum recycled alloy made from aluminum scrap (used automotive components). The method has been validated experimentally, and the results obtained showed that the composition of the recycled alloy was close to that of the predicted one. These findings indicate that the present method can be effectively used for any other recycled alloys to predict the alloy composition based on the in-coming scrap alloys. A deviation factor has been defined in order to understand the composition of the recycled alloy obtained with reference to the ASTM alloy.     

农业高校分析化学课程教学绿色化的改革探索

针对农业高校分析化学课程教学的现状,以绿色化学为主线,进行了分析化学课程教学绿色化的改革探索.从教学理念、教学内容、教学方法和手段、考核手段等方面,提出了一系列改革思路和具体措施,取得了较好的教学效果.     

微细粒铜镍硫化矿浮选的电化学调控

采用电化学调控方法来有效改善易氧化的微细粒硫化镍矿物浮选效果。通过加入氯化调控剂、调整矿浆pH值等措施。实现对硫化铜镍矿物的电化学调控，提高浮选效率。     

Workload Distribution Framework for the Parallel Solution of Large Structural Models on Heterogeneous PC Clusters

One of the main problems of substructure-based parallel solution methods is the imbalances in the condensation times of substructures when direct solvers are used. Such imbalances usually decrease the performance of the parallel solution. Thus, in this study, a workload distribution framework for such methods at heterogeneous computing environment is presented. The main idea behind this framework is to iteratively adjust the shapes of substructures so that the imbalance in their condensation times is minimized. Both generated and actual structural models were solved to illustrate the applicability and the efficiency of this approach. In these examples, a PC cluster having eight different computers was used.     

An Intercomparison Study of Analytical Methods for the Determination of Magnesium in Low Alloy Steel

In an intercomparison study three low alloy steel materials were analyzed on their content of the trace element Mg, and five different analytical techniques were used, namely spark‐OES, inductively coupled plasma optical emission spectrometry (ICP‐OES), inductively coupled plasma time of flight mass spectrometry (ICP‐TOFMS), inductively coupled plasma quadrupole mass spectrometry (ICP‐QMS), and glow discharge mass spectrometry (GD‐MS). Solid steel discs were used for analysis with spark‐OES and GD‐MS. For the analyses with ICP‐OES, ICP‐TOFMS, and ICP‐QMS steel chips were wet‐digested in aqua regia, and the wet‐digestion was performed either in polypropylene tubes placed in a heating block or in Teflon pressure vessels using a microwave assisted system. The Mg concentrations obtained for the three steel materials were: 2.0, 2.8, and 10.3 µg g^?1, respectively, and the spread in results was acceptable, giving RSD values in the range of 20–30%.     

个体认同的意义框架及其作用机制分析

个体认同问题是现代社会凸现出来的重要议题,很多社会问题的产生均与此密切关联.个体认同总是在一定的意义框架下进行的,国家话语、市场话语和地方性话语这三种意义框架分别在中国社会的不同时期和不同地域对个体认同发挥着主导性作用.分析各种意义框架对个体认同的作用机制,有助于我们进一步思考如何建构更完善的文化系统来引导社会个体的自我认同,以期实现更佳的社会控制与社会整合.     

An Analytical Model for Dependence of Force and Forward Slip on Speed in Cold Rolling

An explicit analytical method for determining approximations for roll force and forward slip for strip rolling is introduced. It reproduces all main predictions of classical strip theory, but is completely free of any numerical algorithms. Nevertheless, for extreme cases of cold rolling, like foil or skin pass rolling, more sophisticated algorithms are still needed. For the friction coefficient in the roll gap and its increase from the entry to the neutral point also explicit relations are proposed. In the framework of this analysis, they are sufficiently precise for cold rolling with one‐phase lubricants and stochastic surfaces. Only a single parameter of adaptation is needed, the microscopic friction coefficient μ_micro. The quality of the total model is illustrated by means of the dependence of roll force and forward slip on railing speed. For this purpose measured process data (four different pass‐schedules, seven to ten coils each) for cold rolling of copper with rolling oil is analyzed.     

Approximate Analytical Solution for the Temperature Field in Welding

To determine the temperature fields associated with welding, significant efforts have been made to establish the relative merits of numerical approaches with variable material properties and the analytical approaches with constant material properties. Currently, analytical solutions are either based on the temperature field generated by a point source of heat or are developed for a finite domain derived approximately by using an infinite or semi-infinite heat kernel. Furthermore, the heat kernel applied in these solutions is derived from the Image method (for example, Nguyen’s book (Thermal Analysis of Welds, 2004)). The main problem with the heat kernels obtained from Image method is that they face the problem of singularity at and around the point where the heat source is located, and they do not satisfy the boundary condition accurately. That is why the Laplace transform method has been applied here instead of using the Image method to formulate a heat kernel that (1) converges rapidly, (2) avoids the problem of singularity, and (3) gives a good and robust approximation of the real analytic solution for the temperature field. The results obtained from the analytical solutions were compared with the results obtained from finite element method. The current work is believed to make a considerable contribution to the avoidance of previously mentioned problems by deriving a new approximate analytical solution for the temperature field on a three-dimensional finite body.     

New Variational Solutions for the Rolling of Flanged Sections in Universal Roll Passes

Metallurgist - The variational principle of minimum total power and modern computational means are used to describe the deformation of metal in and to determine the power/force conditions for...     

Research and Application of Flat Roll Technology in the Downstream Stands for CSP

  CVC mills are generally used in the whole stands of CSP (Compact Strip Product). Their special “s” curve of work roll contour and shifting strategy aimed at controlling strip shape, and the characteristics of continuous casting and rolling production, which make the work roll wear in downstream stands seriously uneven, and easily form abnormal transverse profile at the rolling end. As a result, CVC mill configuration in the downstream stands can not meet the profile and flatness control requirement for schedule free rolling, and bring some difficulties in profile and flatness control for the subsequent cold rolling. Based on the characteristics of the shape control system of CSP production line, and combined with the theory of flat roll technology, a kind of technology solution of using flat roll in the downsteam stands for CSP hot strip mills was proposed. At last, industrial test was carried out in the last stand of Masteel CSP, and good results were obtained.     

利用镍的次灵敏线火焰原子吸收法测定镍矿石中高含量的镍

利用镍的 35 2 .45nm吸收线 ,用火焰原子吸收测定了镍矿石中 0 .0 5 %～ 1.3%的镍 ,线性范围在 2 0～ 10 0 0 μg/ 5 0mL ,回收率为 98.1%～ 10 3.8%,RSD(n =10 )为 2 .0 3%,特征灵敏度 0 .116 μgmL-11·10 -2 ,检测下限 0 .0 43μgmL-1。本方法扩大了火焰原子吸收分析镍的线性范围。方法无临近谱线干扰 ,信噪比明显提高。     

An Improved Model for the Longitudinal Peak Strain in the Flange of a Roll Formed U‐Channel developed by FE‐Analyses

Today one can find cold roll forming (CRF) products in many applications, for example vehicles, furniture and in the building industry. Though CRF is a well known sheet metal process, it is still not entirely understood due to the geometrically complex forming. There are several computer aided engineering (CAE) programs on the market that can assist the tool maker when designing a new CRF machine. However, they are often based on simple formulas when predicting the stress and the strain in the strip. The main objective of this study is to improve formulas for the longitudinal peak membrane strain and the deformation length when a U‐channel is formed. These are important since they can be used to determine the number of forming steps and the distance between them. A two‐level factorial design is done using the finite element analysis to investigate which parameters affect the peak strain and the deformation length. The parameters are then used to build models for the peak strain and the deformation length.