注塑件缺陷诊断专家系统的研究及应用

本文建立了一个基于知识的注塑件缺陷诊断专家系统ＫＢＤＤＥＳ。该系统采用不精确推理及确定性理论,按人类专家处理问题的思维方式来协调各专家对问题假设的不确定性,并运用正反向混合推理的控制策略,对常见的注塑件缺陷及注射过程中的故障进行诊断,得出结论并给出避免缺陷或故障的方法及建议。系统知识的表达采用了“框架十规则”的复合表达技术,使不同层次的知识源统一于同一知识表达结构内。     

Design of internal pins in injection mold CAD via the automatic recognition of undercut features

A methodology to deal with the automatic design of internal pins in injection mold CAD via the automatic recognition of undercut features is developed. The approach to automatically identifying the undercut features is first proposed. For the given parting directions, all the inner and outer undercut features are identified based on the topological relationship of geometrical entities. The outer edge loop, which represents the largest cross-section boundary along the given parting directions, is extracted and patched up. The surfaces of molding are then identified based on the classifications of their geometrical entities. To identify the deep inner undercuts in the molding, the projection of the main core, internal pins and their bounding boxes along the parting direction and the pin withdrawal direction are generated. Upon determination of whether the bounding boxes of any two internal pins and the main core projection have intersection area, the deep inner undercuts are located. The complete methodology is finally implemented and verified through case studies and the efficiency of the methodology in handling complex molded parts is thus illustrated.     

浅析基于B／S结构的信息系统的安全问题

安全问题是在设计B／S结构的信息系统时重点需要考虑的问题,本文分析了B／S结构的信息系统的安全隐患并提出了相应的对付策略。     

SQL注入漏洞及防范的研究

随着B/S模式应用开发的发展,相当大一部分程序员在编写代码的时候,没有对用户输入数据的合法性进行判断,使应用程序存在安全隐患。本文从SQL注入的原理入手,对于使用Access和SQL Server数据库的ASP网站,在SQL注入的常用方法和解决办法方面进行了研究。     

Web应用中的攻击防御技术的研究与实现

该文介绍了SQL注入式攻击、XSS跨站脚本攻击、会话劫持3种网络攻击手段的原理,并在此基础上重点论述了如何防范这些攻击的方法。     

MOLDFLOW在产品注塑分析中的应用研究

由于产品的注塑成型过程非常复杂，而注塑的计算机模拟能比较准确的预测产品的质量和存在的问题。本文介绍了Moldflow软件MPI／Stress中的MPI／Cool、MPI／Flow、MPI／Warpage模块的作用，并以标准齿轮为例进行了冷却、模流和翘曲分析，分析和讨论了影响产品质量的主要原因和问题。     

井口注入参数对CO_2注入井井底温度、压力影响研究

CO2驱既可以提高原油采收率又可以实现CO2气体的埋存,是目前国内外研究较多的驱油技术。对于CO2驱,一个重要工作就是根据油藏工程设计的井底压力通过井筒计算来优选井口注入参数,从而为注入井设计提供理论依据。目前CO2注入井筒温度、压力剖面计算主要将井筒中的CO2考虑为单一相态进行计算,因而计算结果精度较差。若将井筒中CO2的相态变化加以考虑,建立计算模型,对实例井进行计算。计算结果与实测结果对比显示模型计算精度较高。在此基础上,对注入温度、注入量等CO2井口注入参数进行了敏感性分析,结果表明,二者对CO2注入井井底温度、压力均有一定影响。     

人工神经网络在注塑参数预测中的应用

应用人工神经网络技术建立了注塑工艺参数值快速预测的双层BP网络模型。利用CAE软件进行模拟，获取训练样本。用Matlab语言编制了应用程序，对网络的训练及参数预测的过程进行求解。将网络预测结果与模拟所得验证数据进行比较和误差分析，显示出BP网络的稳定性和可靠性。经实例验证，表明人工神经网络技术应用于注塑参数值的快速预测和选取方面是可行的。     

定模推件板和动模哈夫斜滑块双向推件注塑模

在分析塑料外壳工艺特性的基础上,优选了注塑模设计方案。论述了模具结构特点和工作原理。该模具采用定模推件板及动模哈夫斜滑块双向推件解决塑件脱模问题。模具结构紧凑,安装操作方便,成型塑件质量好,生产效率高。     

Mechanical properties of textile-inserted PP/PP knitted composites using injection–compression molding

This paper concentrates on the experimental investigation of the self-reinforced all-polypropylene composites. There exists an optimum processing condition to produce high quality specimens by injection–compression molding. Tensile and 3-point bending properties of the virgin PP materials were nearly unaffected by the introduction of reinforcing knit layer(s) due to very low fibre content of the knitted fabrics used. 3-point bending properties were also unaffected by the surface of indentation-flexure. The applied impact energy was maintained at 5 J for the homo-PP and 27 J for the block-PP materials, respectively, to cause penetration during drop-weight impact tests. It is interestingly noteworthy that the self-reinforced homo-PP composites exhibited superior energy absorption capability when compared with the virgin matrix materials. The corresponding plate bending performances of the self-reinforced homo-PP composites also revealed consistent improvement as compared to their virgin counterparts. On the other hand, although virgin block-PP material exhibited better impact performances than its composite reinforced by the homo-PP knitted fabric, a notably small increase in the reinforcement fibre content revealed considerable improvement in the impact properties comparable to those of the virgin block-PP matrix materials. These self-reinforced homo-PP/block-PP materials have clearly indicated that they have the potential to out-perform the block-PP materials via modification and/or manipulation of the reinforcement knit structural/geometrical parameters and the content of reinforcement fibres. Both static and dynamic impact properties are likely to be affected by the local area properties of the tested face under indentation, and thereby contributing to the improved performances of the composite specimens with the knit face under the impact.