地源热泵的地热能利用方式与工程运用

地源热泵是一种新型的高效、节能、环保的空调系统 ,是我国调整能源利用结构 ,发展利用可再生能源策略的重点推广项目之一。本文介绍了地源热泵的工作原理及四种地热能利用方式。根据笔者的设计经验 ,为地源热泵空调系统的工程设计和推广应用提供了一些设计参数和参考意见     

Calculation of fatigue limits of case-hardened specimens with consideration of mean stresses and residual stresses

 The strength of case-hardened parts under cyclic loading can be determined in an experimental manner, but this can produce a large amount of costs due to the expenditure of material and testing time. Therefore, a calculation method is developed, that strongly reduces the number of experiments. The presented model is based on Weibull's weakest-link concept and allows to compute the survival probability of a case-hardened part which is loaded close to the fatigue limit. The essential quantities in this model are the distribution of Vicker's hardness of the material, the exponents of the Weibull distribution of the volume and the surface, the residual stress state, the surface roughness and the surface oxidation depth. By integrating the survival probabilities of the surface and the volume, the survival probability of the entire specimen or part can be calculated, which allows to compute the fatigue limit. The necessary parameters have to be determined from reference specimens. The model is successfully examined by comparing experimental and calculated results of smooth and notched case-hardened specimens under alternating torsion, rotating bending, repeated tension and tension-compression. Received 20 August 2001 / Accepted 11 November 2001     

CAD系统中产品设计三维实体建模方法的研究

三维建模是应用CAD系统进行产品设计的重要步骤。现在市场上已有不少的CAD系统，但是不同系统中的三维建模方法却是基本相同的。在这些三维建模的方法中，往往对用户施加了许多的限制，使得用户无法建立复杂的三维实体。笔者提出了一种新的三维建模方法－折叠法，应用这种方法的概念和原理，可以开发出先进的三维建模CAD系统。折叠二维平面图形构成三维实体是作者提出的一种新概念。     

轻钢结构屋面的应用

针对轻钢结构构屋面系统的性能、特点、构造和施工方法进行了论述，介绍了与传统建筑形成对照的一种新型结构形式，使传统的重盖、肥梁、胖柱、色彩单一的建筑状况得到改善。轻钢结构的优点将使它的生产规模、适用范围不断扩大，从而以其漂亮的外和合理的造价美化人类的生活环境。     

Feature-Based Parametric Design of a Gating System for a Die-Casting Die

This paper presents a semi-automated approach for designing the gating system of a die-casting die. This approach combines the P-Q 2 technique and feature-based parametric design for achieving the automatic generation of the geometries for the gating system. It also enables users to integrate their expertise in the design at an early stage. User-defined gating features are pre-defined and stored in a gating library, and are then retrieved from the library and applied to the gating part with the desired parameters and locations during the design process. Algorithms based on the P-Q 2 technique are proposed for calculating the related parameters of the gating system. A prototype design has been developed using this approach, and the system is able to shorten the time for constructing the 3D geometries of the gating elements such as the gate, runner, overflow, shot sleeve, sprue, etc.     

半导体量子点自组织生长的计算机模拟研究

采用平均场模型和非平均场模型对半导体量子点的自组织生长过程进行了计算机模拟研究。结果表明两种模型给出了相似的量子点的大小分布,但在平均尺寸、数量以及覆盖面积随时间的变化上存在着差别,针对这些差别给出了解释。     

实施ISO14000标准促进中国企业可持续发展

阐述ISO14000标准与国有企业可持续发展的关系。企业按ISO14000建立环境管理体系是企业可持续发展的重要方面，具有战略意义。企业施行ISO14000标准的效能显著，但目前实行IS O14000的企业相对较少。分析了企业施行ISO14000标准存在的困难，提出了建立环境管理体系的几点建议。     

固液相变蓄能的数学模型和自然对流换热系数的实验研究

引入自然对流换热系数 ,将固液蓄能数学模型简化为仅用能量方程加以描述。并通过实验测得相变过程的实际温度场 ,证明了自然对流固液相变换热的影响不可忽略 ,验证了固液相变界面移动速率随自然对流换热系数的增大而增大的定性关系     

臭氧法水处理在空调冷却水系统中的应用

探讨了臭氧法杀菌灭藻，缓蚀，阻垢的机理，认为臭氧法可用于空调冷却水处理，并给出在工程设计中的应用方法。