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ANSI/IEEE Std 1149.1 defines a standard implementation of boundary scan that, it is hoped, will be built into many catalog and application-specific integrated circuits. The standard was developed as a solution to two continuing trends that are having a significant, adverse, impact on the task of testing loaded printed wiring boards: increasing chip complexity and greater miniaturization. The former increases the difficulty of test generation, while the latter impedes access for the bed-of-nails and hand-held probes on which many established test techniques depend.This tutorial provides a guide to the principal features defined by the standard and to their operation. It is intended as a prelude to the standard itself, not as a substitute for it. In particular, it is recommended that readers who intend to implement integrated circuits, design tools, or test systems that support the standard read the standard document before doing so. 相似文献
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Spatial relationships in electrostimulation are examined with a myelinated nerve model. Excitation thresholds are determined for: 1) terminated axon within a locally constant electric field; 2) bent axon within a locally constant field; and 3) a field of finite extent over the affected axon. For application to electromagnetic field standards, the minimum excitation threshold of the in situ electric field applies to a straight, terminated axon; a field measurement averaging distance of 5 mm is recommended. 相似文献
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The possible generation of radiation in the millimeter range based on nanotubes by an alternating (rapidly oscillating) electric field under a constant (or nonstationary) electric field is studied. Radiation enhancement is based on a periodic dependence of the current in nanotubes in such electric fields. The results of a mathematical simulation are presented. 相似文献
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在天线和线缆为耦合途径的情况下,提出了应用于互连系统的差模注入等效替代辐照试验方法,可将注入法的应用频率上限从400 MHz提高到数个GHz水平,并保证了非线性情况下试验的准确性.利用定向耦合器构建耦合装置,实现了差模信号的定向注入和线缆上前向电压的监测.证明了对于线性辅助设备和任意特性受试设备,场强和注入源电压的等效关系是线性的,将该关系作为外推依据,可实现注入等效强场辐照试验.同时,针对受试设备为黑箱的情况,提出将耦合装置监测端电压作为等效依据.以某天线及其射频前端组件为试验对象,验证了不同耦合途径下该试验方法的可行性和准确性. 相似文献
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目的:探讨脉冲电磁场对周围神经损伤后再生作用机制。方法:选30只SD大鼠分成三组:脉冲电磁场治疗组、模型对照组和正常对照组,每组10只。按文献方法钳夹坐骨神经对治疗组和模型对照组大鼠造模。正常对照组不作任何处理,模型对照组不进行脉冲电磁场治疗,治疗组给予0.3mT 2Hz脉冲电磁场治疗三个疗程。治疗方法为2Hz、0.3mT电磁场每天2次,每次3小时。疗程结束后采用免疫组化方法检测上述三组大鼠坐骨神经的神经生长因子-信使核糖核酸(NGF-mRNA)水平,并进行统计学分析。结果:脉冲电磁场治疗组NGFmRNA表达水平明显强于模型对照组(P<0.05)。结论:脉冲电磁场治疗可明显增强坐骨神经损伤后NGFmRNA的表达,促进坐骨神经损伤后的修复与再生,使肢体功能得以恢复。 相似文献
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尽管已经经历了高速成长的20年,但面临着当今电子设计业对系统可配置性更高的要求,可编程器件厂商还是希望藉此实现新一轮的扩张.从Xilinx和Altera两家FPGA领导厂商的策略中,我们可以明显地感觉到他们正在通过技术创新来增强其在各市场领域的渗透力. 相似文献
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IEEE 754标准规定了可以精确表示某一浮点型数据的单精度(常用)和双精度表示方法,这在许多对数据精度要求较高的场合得到广泛应用,而在数据通信过程中所有数据都是以十六进制打包和解析、二进制形式传输的,所以研究如何根据该标准把所要传输的浮点型数据编程转换成8位十六进制数据具有重要的实用意义。这里在分析和研究IEEE 754标准中浮点型数据单精度表示方式的基础上,结合Borland C++Builder 6.0可视化编程工具,阐述了如何把单精度浮点型数据转换成所需要的8位十六进制数,以及如何把8位十六进制数转换成单精度浮点类型数据,并实现显示。 相似文献
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基于IEEE1149.7的新一代测试接口实现与应用 总被引:2,自引:0,他引:2
随着芯片集成度的不断增加和对低功耗设计的重视,原初开发的JTAG(IEEE STD1149.1)面对新的挑战,不能满足当今设计的需要。CJTAG基于IEEE STD1149.7标准和传统的JTAG的边界扫描原理来提供一个更加强大的测试和调试的标准,来达到现在系统的要求。CJTAG用更少的管脚来提供更多的功能,而同时保证了对IEEE1149.1的软件和硬件的兼容性。 相似文献
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随着信息化的建设在现代企业中的迅速发展,充分利用网络资源优化企业生产、提高效率、节约成本显得越发重要。文中论述了基于C/S结构的销售管理系统的设计思路、主要功能模块、实现方法,最终实现企业销售数据的一致性、完整性,为销售主管提供可靠的数据依据,为单位的高层决策者提供更及时的市场分析。 相似文献
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A procedure is presented for estimating the mean waiting time in an M/D/C queue with two levels of nonpre-emptive priority. The approximation gives a maximum relative error of 10% for heavy load and is greater than the simulated results. This makes the procedure useful for evaluating trunked radio systems 相似文献
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Rate-equation calculations are used to model accurately the near-threshold behavior of a Co:MgF2 laser operating at room temperature. The results demonstrate the limitations of the conventional threshold analysis in cases of practical interest. This conclusion is applicable to pulsed solid-state lasers in general. The calculations, together with experimental data, are used to determine emission cross sections for the Co:MgF2 laser 相似文献
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为了方便农机手能够迅速、准确地知道机具作业的深度,提出一种基于NEC单片机的田间超声波测距方法,设计非刚性接触地面仿形装置和电子控制系统,利用超声波测距传感器和NEC单片机,通过NEC专用软件开发工具Applilet自动生成代码,在PM+集成环境平中建立目标源文件,最后将程序经烧写器烧入到单片机中实现控制任务.驾驶员通过观察LCD显示的实时运行参数,LED状态指示灯,或根据蜂鸣器报警等情况及时监测和调整机具作业深度,本研究为研制智能化装备提供了开发平台. 相似文献
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