Development of transfer type variable lamination manufacturing (VLM-st) process

RP technologies have been widely used to reduce the lead-time and development cost of new products. However, most of the developed RP technologies have disadvantageous characteristics, due to their working principle: a large building time, a stair-stepped surface of a part and additional post-processing. In addition, it requires a high cost to install, operate and maintain the RP apparatus.The objective of this paper is to propose a new rapid prototyping system, transfer type variable lamination manufacturing process using expandable polystyrene foam (VLM-st), to overcome the disadvantages. VLM-st has various technical novelties such as a thick layer with thickness of less than 4 mm, a sloped surface with the first order approximation between the top and bottom surfaces of each layer, a stacking method using the pilot pin and building board, a concept of unit shape layer (USL), and a synchronized four-axis hotwire cutter with linear heat source and a parallelogram mechanism.In this paper, the characteristics and the key features of VLM-st are discussed. In order to investigate the applicability of the new RP process, various prototypes, such as an extruded shape, son-o-kong shape, a world-cup logo, and a human head shape, are manufactured by the prototype of the VLM-st apparatus. All shapes are manufactured within one hour. In addition, the efficiency of the new RP process is examined by comparing the world-cup logo shape and the human head shape with those of Laminated Object Manufacturing (LOM) from the viewpoint of geometrical conformity, total building time, building cost, and dimensional accuracy.     

电网黑启动的广义模式评估算法

在实际黑启动模式的决策中,需要对电网可能存在的各种启动模式进行全方位分析和比较.文章提出了广义模式评估的概念,对各模式的黑启动边界条件、技术问题和整改措施进行分析,并综合比较了其成本及可靠性,从时间性、结构性、经济性和可靠性四个方面提取广义黑启动模式评估的指标,最终结合实例用层次化数据包络分析(DEA/AHP)方法对黑...     

Physical modification of polyetheretherketone for orthopedic implants

Polyetheretherketone （PEEK） is regarded as one of the most potential candidates for replacing current implant applications. To obtain good bone-implant interfaces, many modification methods have been developed to enable PEEK and PEEK- based composites from bio-inert to bioactive. Among them, physical methods have aroused significant attention and been widely used to modify PEEK for orthopedic implants. This review summarizes current physical modification techniques of PEEK for orthopedic applications, which include composite strategies, surface coating methods and irradiation treatments. The positive consequences of those modification methods will encourage continuing investigations and stimulate the wide range of applications of PEEK-based implants in orthopedics.     

大跨度双塔悬索桥在地震动行波激励下的响应规律研究

本文以一座主跨850m的大跨双塔悬索桥为工程背景,采用时程分析法研究了行波效应大跨双塔悬索桥地震响应的影响。通过建立三维有限元分析模型,在分析了大跨度双塔地锚式悬索桥动力特性及一致激励下地震响应规律的基础上,进一步探讨了行波效应对大跨双塔地锚式悬索桥地震响应的影响规律。分析结果表明:地震波纵向行波作用下,主塔的地震响应随着视波速的减小而先减小后增大;主梁的竖向振动则较一致激励下显著增大;主缆及吊索轴力则受地震动行波效应的影响不大。     

路灯配电系统若干问题的探讨

通过一路灯照明工程实例,探讨了路灯配电系统中的单相接地保护灵敏度校验、保护设置、接地型式选择等问题。路灯的保护应包括两级:配电线路干线保护和灯具短路保护,在TN-S系统中,路灯配电干线开关可选用B类断路器,在TT系统中,可选用RCD或其组合电器。每个灯具处宜设置短路保护,TN-S中可选用熔断器,在TT系统中,当接地电阻值较大时,可选用RCD作灯具的短路保护。路灯不宜采用TN-C系统,可考虑采用II类绝缘设备。     

基于CAN总线的EPB控制器的设计

研究了CAN总线在汽车EPB系统的应用,设计了一种EPB系统的控制器。通过CAN总线进行数据通信,并给出了控制器关键功能的部分软件及硬件电路,EPB控制器在驻车测试中能有效地驱动EPB系统。     

基于CAN控制器MCP2515-I/SO的模拟SPI串口通信的应用

SPI接口是单片机应用系统中常用的串行扩展接口之一,通过汽车EPB辅助控制器设计的具体项目的应用,重点介绍了基于SPI的CAN控制器与单片机通信的连接方法,及模拟SPI总线时序的软件实现。     

一种时延保证的QoS路由协议

针对无线传感器网络中多跳视频传输实时性难以保证以及节点失效造成的传输中断问题,本文在比较分析了考虑时延的路由协议基础上,提出并设计了一种保证时延QoS要求可自我修复的路由协议(Self Repaired and Delay Guarantee Routing Protocol)。该协议选择时延最短的节点作为路由节点,缩短了多跳传输时间;在路由表中增加备选路由节点,当某个路由节点失效时,自动启用备选节点修复路由,节省了路由重新建立的时间,保证了视频传输持续性。仿真结果表明该路由协议能够较好地满足无线传感器网络中多跳视频传输的时延要求。     

Influence of SBS modifiers on viscoelastic mechanical behavior of modified asphalt

In order to verify the influence of different block proportions S/B on the effect of SBS modified asphalt,the dynamic mechanical performance test and static loading test were performed on the samples composed of different kinds of SBS with base asphalt. It is found that different S/B values fix on different modified effects and different viscoelastic mechanical behaviors,due to biphasic separate fabric of polybutadiene and polystyrene in SBS. In low-speed running pavement,the modified asphalt with lower S/B value shows better pavement performance,while in high-speed running pavement,the modified asphalt with higher S/B value shows better pavement performance. As far as SBS modified asphalt itself is concerned,mixing proportion impacts on resisting displacement and block proportion S/B ratio impacts on strain recovery capacity. In the case that the conditions are the same,SBS modified asphalt with different S/B values can be used for different travelling speed pavement construction demands to get an intelligent use.