Experimental study on fitness of one-piece casting osseointegrated implant frameworks with relation to fixture abutment positions

An experiment on fitness of one-piece casting osseointegrated implant frameworks was performed among three fixture abument positions where other conditions were controlled. The result revealed that there was statistically significant differences in dimensional change among the three fixture abument positions. In terms of the relation between abument position and fitness, the more backward the abument position was, the worse the osseointegrated framework fitness was. The frameworks showed deformations in "arch form" and "warp" in three dimensions.     

近水平孔水力纠偏自动定向方案及其硬件实现

根据煤层气近水平孔钻进的实际需求,结合水力纠偏技术,提出了一种水力纠偏射流自动定向方案,并在此基础上设计了一种纠偏系统。该纠偏系统以单片机为控制核心,采用压力传感器监测钻井液压力的变化以启动或停止整个水力纠偏钻进过程,以倾角传感器和电子罗盘分别采集水平钻孔的倾角和方位角,单片机根据方位角和倾角的值及其互相关系确定射流方向后控制步进电动机调整射流方向。室内调试证明了该射流自动定向方案的可行性。     

皮革水分及其挥发物测定仪的设计

为了提高皮革水分及其挥发物测定精度,缩短测定时间,降低成本,采用24位超低噪声模数转换器ADS1232,结合红外加热、Bang-Bang控制、PID控制和多种抗干扰措施,设计出一款高性能皮革水分及其挥发物测定仪(简称:皮革水分仪);ADS1232高集成模块的应用,不但简化了硬件和软件设计,而且也解决了桥接传感器的前端问题和传统的高精度A/D转换电路需要加前置放大器而带来的成本及信号漂移问题;通过实验,仪器敏感度可达1mg,测量误差小于0.1%,试制样机与传统仪器相比,测量时间短,精度高,操作简单,性价比高.     

钢铁企业能源中心系统设计

在钢铁企业生产过程中,能源的稳定供给是保证正常生产的必备条件之一.如何高效、合理利用能源,已成为当今钢铁企业必须面对和亟待解决的战略问题.为了加强对钢铁企业复杂多样的能源介质和能源设施的综合管理,以国内某大型钢铁联合企业为背景,针对该企业能源管理分散和调度系统独立等问题,从系统总体结构和系统主要功能等方面介绍了能源中心...     

浅谈工科院校艺术设计专业人才培养模式

随着社会对艺术设计人才需求的不断增长,许多工科院校也开始设置艺术设计专业,那么对艺术设计专业的人才培养模式就要改革,不能照搬纯艺术的培养模式或套用传统的工科人才培养模式。本文探讨了工科院校艺术设计专业人才培养模式改革的问题,提出构建适应现代社会发展趋势和客观要求的工科院校艺术设计专业人才培养模式改革,是有着重要的理论意义和实践意义的。     

一种基于GSM-R的GMSK信号调制解调方法的实现

文章介绍了GMSK的调制原理和特点,在详细分析了GMSK信号产生过程的基础上,提出了一种实现GM—SK调制和解调的具体实现方法,并在Matlab平台上进行了仿真,仿真结果验证了该文方法的正确性。仿真程序也为真正实现GMSK数字化调制与解调提供了很好的参考。     

基于HS-3282的DSP与ARINC429总线通讯模块设计

设计了以芯片HS-3282为核心的DSP与ARINC429总线通信模块。该模块可实现DSP与ARINC429总线之间数据的高速、可靠的传输。模块主要由数据收发电路和逻辑控制电路组成。数据收发电路主要采用HS-3282完成数据的格式转换。逻辑控制电路由DSP和逻辑门电路组成,DSP发出的控制指令经地址译码后直接控制HS3282芯片,使芯片严格按照数据接收和发送的时序工作。测试表明,模块可实现DSP与429总线之间的数据通讯。     

Security analysis of two recently proposed RFID authentication protocols

Radio frequency identification (RFID) systems suffer many security risks because they use an insecure wireless communication channel between tag and reader. In this paper, we analyze two recently proposed RFID authentication protocols. Both protocols are vulnerable to tag information leakage and untraceability attacks. For the attack on the first protocol, the adversary only needs to eavesdrop on the messages between reader and tag, and then perform an XOR operation. To attack the second protocol successfully, the adversary may execute a series of carefully designed challenges to determine the tag’s identification.     

CHV190系列变频器在永磁同步电机驱动矿井提升机中的应用

本文分析了矿井提升机的运行特点,详细阐述了英威腾CHV190系列起重提升专用变频器用于永磁同步电动机驱动的节能型矿井提升机的选型配置原则,最后介绍了应用现场的调试步骤及注意事项。     

Anisotropic diffusion with generalized diffusion coefficient function for defect detection in low-contrast surface images

In this paper, an anisotropic diffusion model with a generalized diffusion coefficient function is presented for defect detection in low-contrast surface images and, especially, aims at material surfaces found in liquid crystal display (LCD) manufacturing. A defect embedded in a low-contrast surface image is extremely difficult to detect, because the intensity difference between the unevenly illuminated background and the defective region is hardly observable and no clear edges are present between the defect and its surroundings.The proposed anisotropic diffusion model provides a generalized diffusion mechanism that can flexibly change the curve of the diffusion coefficient function. It adaptively carries out a smoothing process for faultless areas and performs a sharpening process for defect areas in an image. An entropy criterion is proposed as the performance measure of the diffused image and then a stochastic evolutionary computation algorithm, particle swarm optimization (PSO), is applied to automatically determine the best parameter values of the generalized diffusion coefficient function. Experimental results have shown that the proposed method can effectively and efficiently detect small defects in various low-contrast surface images.