建筑材料中放射性核素限量标准的探讨

《建筑材料放射性核素限量》（GB6566—2001）结束了我国建材标准长期不统一的局面，规定了对建材中放射性实现强制检定的要求，但在装修材料分类、空心材料、废渣利用、测量方法等方面存在着一些不合理的规定。与以往的国家标准相比。对建材中的放射性控制明显放宽，甚至比原来的建材行业标准对石材的控制还要宽，影响了公众的辐射防护安全。对此进行了详细的分析和讨论。     

Finite element shakedown analysis of two‐dimensional structures

In the present paper, the formulation proposed by Casciaro and Garcea (Comput. Meth. Appl. Mech. Eng., 2002; 191 :5761–5792) and applied to the shakedown analysis of plane frames, is extended to the analysis of two‐dimensional flat structures in both the cases of plane‐stress and plane‐strain. The discrete formulation is obtained using a mixed finite element in which both stress and displacement fields are interpolated. The material is assumed to be elasto‐plastic and a linearization of the elastic domain is performed. The result is a versatile iterative scheme well suited to implementation in general purpose FEM codes. An extensive series of numerical tests is presented showing the reliability of the proposed formulation. Copyright © 2005 John Wiley & Sons, Ltd.     

建设项目的投资工期和质量控制

根据监理工作实践，论述了投资、工期和质量的控制，提出控制工期是保证投资效益的重要途径，控制质量是保证工程投资的有效手段；设计阶段是投资控制的重要环节。     

两个更一般的求极限公式

推广了文献[1～3]的结果，给出了两个更为一般的求极限公式。     

浅论拱坝坝肩抗震稳定

本文从拱坝震害,分析了拱坝抗震的特点、薄弱部位和坝肩动力失稳的过程,指出了拱坝坝肩抗震稳定分析与边坡稳定分析的不同之处,探讨了失稳安全系数的定义和意义,最后,回顾了基于现行抗震规范要求的刚体极限平衡方法并指出了其局限性,以及“九五”攻关期间所采取的改进措施,提出了更切近实际,能反应拱坝抗震稳定诸特点,从概念和方法上都有别于传统的刚体极根平衡法的新的拱坝坝肩抗震稳定分析方法,以及与之相配套的以坝体为主体的坝肩岩体稳定的工程安全准则。     

适时调整矿山生产计划以适应钼价格波动

不同的经济技术条件确定不同的开采境界。钼价格的波动对钼矿山的生产影响非常大。作为企业就要以市场为先导，根据变动的钼价格确定短期开采境界，及时对矿山生产做出调整，以使企业的经济效益最佳。     

Axial offset control of PWR nuclear reactor core using intelligent techniques

Improved load following capability is one of the main technical performances of advanced PWR (APWR). Controlling the nuclear reactor core during load following operation encounters some difficulties. These difficulties mainly arise from nuclear reactor core limitations in local power peaking, while the core is subject to large and sharp variation of local power density during transients. Axial offset (AO) is the parameter usually used to represent of core power peaking, in form of a practical parameter. This paper, proposes a new intelligent approach to AO control of PWR nuclear reactors core during load following operation. This method uses a neural network model of the core to predict the dynamic behavior of the core and a fuzzy critic based on the operator knowledge and experience for the purpose of decision-making during load following operations. Simulation results show that this method can use optimum control rod groups maneuver with variable overlapping and may improve the reactor load following capability.     

Generalized notions of mind change complexity

Gold introduced the notion of learning in the limit where a class S is learnable iff there is a recursive machine M which reads the course of values of a function f and converges to a program for f whenever f is in S. An important measure for the speed of convergence in this model is the quantity of mind changes before the onset of convergence. The oldest model is to consider a constant bound on the number of mind changes M makes on any input function; such a bound is referred here as type 1. Later this was generalized to a bound of type 2 where a counter ranges over constructive ordinals and is counted down at every mind change. Although ordinal bounds permit the inference of richer concept classes than constant bounds, they still are a severe restriction. Therefore the present work introduces two more general approaches to bounding mind changes. These are based on counting by going down in a linearly ordered set (type 3) and on counting by going down in a partially ordered set (type 4). In both cases the set must not contain infinite descending recursive sequences. These four types of mind changes yield a hierarchy and there are identifiable classes that cannot be learned with the most general mind change bound of type 4. It is shown that existence of type 2 bound is equivalent to the existence of a learning algorithm which converges on every (also nonrecursive) input function and the existence of type 4 is shown to be equivalent to the existence of a learning algorithm which converges on every recursive function. A partial characterization of type 3 yields a result of independent interest in recursion theory. The interplay between mind change complexity and choice of hypothesis space is investigated. It is established that for certain concept classes, a more expressive hypothesis space can sometimes reduce mind change complexity of learning these classes. The notion of mind change bound for behaviourally correct learning is indirectly addressed by employing the above four types to restrict the number of predictive errors of commission in finite error next value learning (NV′′)—a model equivalent to behaviourally correct learning. Again, natural characterizations for type 2 and type 4 bounds are derived. Their naturalness is further illustrated by characterizing them in terms of branches of uniformly recursive families of binary trees.     

Process Quality Analysis of Products

Process capability indices are widely regarded as a flexible means of evaluating the quality and performance of a process. Accreditation by the Quality System Requirement QS9000 requires an agent to conduct a global evaluation on the process capability over the entire product family from a plant. Generally, the process capability of the whole product family is an important reference for evaluation when producing a new product or designing a new process. Therefore developing a scheme to evaluate the process capability of the whole product family or series is crucial for industry. This paper takes the production of capacitors as an example of a new method for evaluating the process capability of a whole product family. As the quality characteristic for producing capacitors is "the smaller the better", the upper specification limits of the capacitors of various specifications should first be established. The process capability index Cpu for products for which "smaller is better" is then used as an evaluation tool to calculate the process capability indices for individual specified products. The relationship between the process capability indices and the yield will be studied. A process capability index is proposed to reflect the global yield of the whole product family and to serve as a reference for evaluating process capability for designing new processes or developing new products. The process capabilities for all products can thus be evaluated and the performance of each process can be evaluated according to the colour management method. Managers can determine easily whether products meet their specifications and take action to improve them if necessary, according to the colour management method.     

考虑动作误差的低励限制与失磁保护定值配合方法研究

关于低励限制与失磁保护定值匹配的研究多聚焦于将其转换到同一功率平面或阻抗平面进行校核的方法,鲜有文献考虑实际装置动作特性对定值匹配结果的影响。该文从理论上详细分析各参数变化对失磁保护和低励限制的影响,提出基于装置动作误差的低励限制与失磁保护定值匹配校核原则,并论述定值失配时的定值调整方法,为当前各发电厂开展低励限制与失磁保护定值校核及整定提供了有效指导原则。