以太网热敏打印机控制装置的研制

利用热敏打印机体积小、速度快、噪音低、打印清晰等优点,结合目前应用十分广泛的基于TCP/IP协议的以太网技术,设计基于以太网的热敏打印机嵌入式控制装置。本文介绍系统开发的总体方案,系统主要包括硬件设计和软件设计,硬件部分以LM3S8962为控制核心,设计打印头步进电机驱动电路,缺纸和温度检测与保护、键盘与TFT、以太网接口等电路。软件部分设计上位机人机界面、以太网通讯软件,控制装置嵌入μC/OS-II实时操作系统,进行任务的划分和应用层任务软件、文字和图形打印,以太网驱动和步进电机驱动、温度检测与保护等软件设计。     

对电力免维护接地装置的探讨

传统的接地装置耐腐蚀能力差,使用寿命短,安全性能低,维护成本高。本文介绍了用铜包钢做成接地体和接地线,使接地装置全部组成元件都具有铜材的良好抗自然腐蚀能力的免维护的接地装置,分析了其保障人身安全、设备安全和电力系统安全的优越性。在此基础上,提出了免维护接地装置的制造工艺和设计要求,并对其应用前景进行了展望。     

Musculoskeletal symptoms among mobile hand-held device users and their relationship to device use: A preliminary study in a Canadian university population

The study aims were, in a population of university students, staff, and faculty (n = 140), to: 1) determine the distribution of seven measures of mobile device use; 2) determine the distribution of musculoskeletal symptoms of the upper extremity, upper back and neck; and 3) assess the relationship between device use and symptoms. 137 of 140 participants (98%) reported using a mobile device. Most participants (84%) reported pain in at least one body part. Right hand pain was most common at the base of the thumb. Significant associations found included time spent internet browsing and pain in the base of the right thumb (odds ratio 2.21, 95% confidence interval 1.02–4.78), and total time spent using a mobile device and pain in the right shoulder (2.55, 1.25–5.21) and neck (2.72, 1.24–5.96). Although this research is preliminary, the observed associations, together with the rising use of these devices, raise concern for heavy users.     

Pricing strategies for tied digital contents and devices

Media companies are increasingly offering digital content to consumers. Many of these companies are tying digital content with their proprietary digital devices. In this study, we develop a consumer demand model for digital device and digital content based on a constant elasticity demand function. In modeling consumer valuation of the digital device, we take consumer surplus on digital content into account. We further derive equilibrium prices for digital devices based on an oligopoly competition model with horizontal product differentiation. We analyze the equilibrium prices and how prices affect firm profits. We find product differentiation and the level of product substitutability affect prices. We also find that content price plays a significant role in affecting the price of the digital device. Content price can either increase or decrease the tied digital device price depending on the profit margin and demand elasticity of the digital content. We further analyze how content and device prices affect their respective profits and the overall profit of the firm. We extend our model to vertical product differentiation and find vertical product differentiation and the level of product quality affect prices.     

嵌入式Linux下PCI设备驱动的设计与实现

PCI局部总线具有使用方便、数据传输率高等特点,已成为计算机必备的一种接口。Linux是一种日趋成熟完善的操作系统,越来越多的软硬件厂商开始使用Linux平台开发自己的产品,因而对基于该平台的设备驱动程序的需求也愈来愈多。介绍了Linux驱动程序开发的一般方法,并实现了流媒体数据缓存PCI卡在Linux环境下的驱动程序。     

基于嵌入式Linux的绣花机实时控制软件设计

介绍了基于ARM9处理器S3C2440和嵌入式Linux操作系统的绣花机电控系统实时控制软件的设计,详细论述了在非实时操作系统下软件如何实现实时控制,并对驱动程序设计做了说明.     

飞机逃逸控制系统电磁兼容设计

飞机逃逸系统对可靠性有非常高的要求,但由于飞机内复杂的电磁环境,逃逸系统的电磁兼容性设计便尤为重要。本文给出从元器件布局与布线、电磁屏蔽、隔离技术以及双绞线应用在内的完整电磁兼容解决方案,实际应用说明电磁兼容性能达到设计要求,系统运行可靠。     

现代数控系统的微处理器结构分析

数控系统是推动数控技术发展的关键因素。自微处理器问世以来,以微处理器为基础的微型计算机数控逐渐取代了小型计算机数控。数控系统从硬件结构上,一般分为单微处理器和多微处理器结构两类,现今主要以多微处理器为主。     

基于RS485总线的监控系统研究与设计

PID调节仪表与传感器配合使用,可以实现对钢制品生产线上罩式炉温度的测量与显示。通过相应的执行器,可以实现对相关罩式炉设备的PID调节和控制、报警控制、数据采集和记录。然而对于具备多条生产线,而每条生产线使用多个PID调节仪表的现场环境而言,依次对每个仪表进行操作并不方便。采用Borland C++Builder 6设计了PID调节仪表的在线集中监控系统。,利用Borland C++Builder 6功能强大的图形化控制界面,及SPComm控件在串行口下编程,通过USB转RS485协议转换器,很好地实现了对生产线上各个分区仪表的实时监测与远程控制。     

基于线性旋转变压器的角度测控装置设计

某大型设备要求从水平状态起竖到垂直状态,在这个过程中,其液压系统工作的流量和压力是根据起竖角度而定的,所以,对该角度值的测量直接关系到对流量压力的控制精度。本文介绍了角度装置设计中的几个问题,对信号检测,测量结果不确定度分析等内容作了详细论述。