兰州地铁砂卵石地层土压平衡盾构刀具使用寿命延长技术

为了降低刀具的磨损,延长刀具的使用寿命,以兰州地铁工程施工案例为背景,对土压平衡盾构在砂卵石地层中掘进刀具磨损的问题进行了跟踪研究。通过理论计算与工程实际对比分析得出刀具的磨损规律,在刀盘设计和刀具组合等研究成果的基础上,对渣土改良、盾构掘进参数、盾构姿态和一般欠土压模式掘进等控制措施进行了系统的研究和实践,成功地延长了刀具使用寿命,减少了刀具更换的次数,加快了工程进度并降低了工程成本;同时,解决了土压平衡盾构在砂卵石地层掘进刀盘被卡、地面沉降控制等技术难题。     

Examining stakeholder participation and conflicts associated with large scale infrastructure projects: the case of Tema port expansion project,Ghana

ABSTRACT

Balancing economic activities with socio-environmental considerations has become a global standard for the construction of large scale infrastructure projects, including ports. In this discourse, stakeholder participation and environmental and social impact assessment (ESIA) have been stressed as important tools that can help port managers to co-create values, avoid conflicts and promote inclusive growth. Drawing on qualitative research tools and stakeholder theory, this paper explores whether and to what extent local stakeholders’ inclusion has substantial influence on addressing their socio-cultural concerns and interest. This is illustrated with a case study of an ongoing port expansion project at Ghana’s largest port of Tema. The findings suggest that although the port authority conducted an ESIA and engaged local stakeholders as part of the planning process, this did not translate into preventing the loss of valuable cultural resources of the local communities. The port authority did not place ‘value’ on cultural resources of the local communities that cannot be expressed in monetary terms. Further, lack of good faith engagement with local stakeholders led to conflicts in some cases that triggered a court action and delays. The paper concludes that stakeholder participation if not applied well, can become a ‘post-political’ tool.     

Fabrication and drilling tests of chemical vapor deposition diamond coated drills in machining carbon fiber reinforced plastics

Chemical vapor deposition (CVD) diamond coated drills are fabricated by depositing diamond films on Co-cemented tungsten carbide (WC-Co) drills. The characteristics of as-deposited diamond coatings are investigated by scanning electron microscope (SEM) and Raman spectra. To evaluate the cutting performance of diamond coated drills, comparative drilling tests are conducted using diamond coated and uncoated WC-Co drills, with carbon fiber reinforced plastics (CFRPs) as the workpiece on a high-speed computer numerical control (CNC) machine. Thrust force and tool wear are measured during the drilling process. The results show that diamond coated drill exhibits better cutting performance, compared with the uncoated drill. The value of flank wear is about 70 μm after machining 90 holes, about a half of that of theWC-Co drill with 145μm after drilling only 30 holes. The wear rate of WC-Co drill is higher than that of diamond coated drill before diamond films peeling off. The diamond coated drill achieves more predictable hole quality. The improved cutting performance of the diamond coated drill is due to the high hardness, wear resistance and low coefficient of friction.     

基于斯太尔平衡轴轴承间隙测量方法的探究

平衡轴是重型汽车的重要组成部分,然而斯太尔平衡轴作为一款经典的整体式平衡轴,广泛应运于重型汽车行业。斯太尔平衡轴的结构较为复杂,分装过程繁琐,若不能严格按照装配工艺要求进行操作,就会出现平衡轴漏油、轴承磨损等失效模式。由于受测量手段的约束,在平衡轴分装过程中最困难的就是如何测量出轴承轴向0.1-0.3mm的间隙,从而进一步地正确选配斯太尔技术所给的七种定位垫圈。本文从假设使用工装代替平衡轴头出发,模拟平衡轴分装过程,用测量规间接测出轴承轴向间隙,再加上理论值,从而得出定位垫圈的厚度,进行正确选配定位垫圈。     

半主动动力吸振镗杆系统的颤振抑制机理

深孔镗削过程中,针对影响工件加工精度和表面质量的颤振现象,建立单自由度切削颤振系统的动力学模型,利用谐波平衡法求得机床主轴转速与极限切削宽度的关系式,并绘制了机床主轴转速与极限切削宽度的稳定性图,结合半主动动力吸振镗杆刚度和阻尼系数的可控性,分析了机床结构刚度及阻尼系数大小对颤振抑制的影响。研究结果表明：机床颤振频率随着主轴转速呈分段线性变化,增大机床结构的刚度和阻尼,系统的稳定性区域在一定范围内相应的增大。为今后进行半主动动力吸振镗杆具体模型的建立和相关参数的选取提供了理论依据,具有实际意义。     

深水铺管船托管架总装工艺探讨

托管架是深水管道铺设中的重要设备之一,结合深水铺管起重船托管架建造项目,针对托管架的装配特点,从托管架的制造精度控制、虚拟装配、吊装、工装设计等方面对深水铺管托管架的海上总装工艺进行了探讨,进而为大型结构物的海上装配提供了技术参考.     

基于J2EE电子留言系统的设计与实现

传统的电子留言系统将页面,业务和数据混杂在一起,使得系统存在耦合性高,重用性、可维护性、可扩展性差以及Web用户界面响应灵敏性低等缺陷.提出采用Struts框架和Hibernate持久层,设计并实现一个电子留言系统,该系统分离页面逻辑、业务逻辑和数据逻辑,达到结构上松散耦合,提高重用性、可维护性和可扩展性的目的.此留言系统的特点是简洁实用,安全可靠,可维护性强,适用于通用网站.     

基于Hibernate+Spring+Struts的Web应用开发框架

介绍Hibernate,Spring和Struts开源框架,根据这3种框架整合出一种新的Web应用开发框架,分析该框架的特点.在该框架中,采用Struts架构表示层,Spring架构业务层,Hibernate架构持久层.     

车载自诊断的原理及使用

阐述车载自诊断系统对传感器、电控单元、执行器和多路传输系统的诊断原理;说明在自诊断过程中产生的故障代码和在使用中读取、清除故障代码的过程,以及使用自诊断的注意事项。介绍故障检测仪的功能,对自诊断系统的发展趋势作了展望。     

直线电机在数控机床中的应用

文章介绍了直线电机的发展,直线电机的工作原理及控制技术,并就其特点和优势作了论述,最后介绍了直线电机在数控机床中的应用实例。