自回归功率谱密度（AR-PSD）方法的基础是生物组织的离散散射体模型〔超声体模〕理论，该模型认为生物组织为半规则的散射体分布的，这种方法是基于温度和频移的相关特性。本文介绍超声回波信号对HIFU（High Intensity Focused Ultrasound）治疗的测温技术，从测温模型和算法，实验仪器的设计和构建，仿真和离体实验中获取了一套有效的测温方法，利用Matlab7.1和VC++6.0作为工具对超声回波信号进行计算机仿真，并从实验获得的超声回波信号中分析出具体的温度变化，验证了算法的可行性。
上传时间： 2013-11-13
上传用户：eastimage
Abstract: This application note presents an overview of electronic margining and its value in detectingpotential system failures before a product ships from the factory. It is a calibration method that effectivelypredicts and allows adjustments to improve product quality. Margining also can be used to sort productsinto performance levels, allowing premium products to be sold at premium prices. We discuss thedownside of sorting and suggest alternative ways to segregate products.
上传时间： 2014-01-22
上传用户：lhw888
微电脑型RS-485显示电表（24*48mm/48*96mm） 特点： 5位数RS-485显示电表 显示范围-19999-99999位數 通訊协议Modbus RTU模式 宽范围交直流兩用電源設計 尺寸小,穩定性高 主要规格： 显示范围:-19999~99999 digit RS-485传输速度: 19200/9600/4800/2400 selective RS-485通讯位址: "01"-"FF" RS-485通讯协议: Modbus RTU mode 显示幕: Red high efficiency LEDs high 10.16 mm (0.4") (MMX-RS-11X) Red high efficiency LEDs high 20.32 mm (0.8") (MMX-RS-12X) Red high efficiency LEDs high 10.16 mm (0.4")x2 (MMX-RS-22X) 参数设定方式: Touch switches 记忆方式: Non-volatile E²PROM memory 绝缘耐压能力: 2KVac/1 min. (input/power) 使用环境条件: 0-50℃(20 to 90% RH non-condensed) 存放环境条件: 0-70℃(20 to 90% RH non-condensed) CE认证: EN 55022:1998/A1:2000 Class A EN 61000-3-2:2000 EN 61000-3-3:1995/A1:2001 EN 55024:1998/A1:2001
上传时间： 2015-01-03
上传用户：feitian920
微电脑型单相交流集合式电表（单相二线系统） 特点： 精确度0.25%满刻度±1位数 可同时量测与显示交流电压,電流,頻率,瓦特,(功率因數/視在功率) 交流電壓,電流,瓦特皆為真正有效值(TRMS) 交流電流,瓦特之小數點可任意設定 瓦特單位W或KW可任意設定 CT比可任意設定(1至999) 輸入與輸出絕緣耐压 2仟伏特/1分鐘( 突波測試強度4仟伏特(1.2x50us) 數位RS-485界面 (Optional) 主要规格： 精确度: 0.1% F.S.±1 digit (Frequency) 0.25% F.S.±1 digit(ACA,ACV,Watt,VA) 0.25% F.S. ±0.25o(Power Factor) (-.300~+.300) 输入负载: <0.2VA (Voltage) <0.2VA (Current) 最大过载能力: Current related input: 3 x rated continuous 10 x rated 30 sec. 25 x rated 3sec. 50 x rated 1sec. Voltage related input: maximum 2 x rated continuous 过载显示: "doFL" 显示值范围: 0~600.0V(Voltage) 0~999.9Hz(Frequency)(<20% for voltage input) 0~19999 digit adjustable(Current,Watt,VA) 取样时间: 2 cycles/sec. RS-485通讯位址: "01"-"FF" RS-485传输速度: 19200/9600/4800/2400 selective RS-485通信协议: Modbus RTU mode 温度系数: 100ppm/℃ (0-50℃) 显示幕: Red high efficiency LEDs high 10.16 mm(0.4") 参数设定方式: Touch switches 记忆型式: Non-volatile E²PROM memory 绝缘抗阻: >100Mohm with 500V DC 绝缘耐压能力: 2KVac/1 min. (input/output/power) 1600 Vdc (input/output) 突波测试: ANSI c37.90a/1974,DIN-IEC 255-4 impulse voltage 4KV(1.2x50us) 使用环境条件: 0-50℃(20 to 90% RH non-condensed) 存放环境条件: 0-70℃(20 to 90% RH non-condensed) CE认证: EN 55022:1998/A1:2000 Class A EN 61000-3-2:2000 EN 61000-3-3:1995/A1:2001 EN 55024:1998/A1:2001
上传时间： 2015-01-03
上传用户：几何公差
集合式直流电能表（小功率的） 特点： 精确度0.05%满刻度±1位数 可同时量测与显示/直流电压/电流/瓦特（千瓦）/瓦特小时（千瓦小时） 电压输入（DC0-99.99V/0-600.0V）自动变档功能 显示范围0-9999(电流/瓦特/千瓦),0至99999999(八位數瓦特小时)可任意规划 数位RS-485 界面 (Optional) 主要规格： 辅助电源消耗功率：＜0.35VA(DC12V/DC24V) ＜0.5VA（DC48V） ＜1.5VA（AC90-240V(50/60Hz)） 精确度: 0.05% F.S. ±1 digit (23 ±5℃) 输入范围：Auto range(DC0-99.99V/0-600.0V(DC voltage)) 输入抗阻：＞5MΩ（DC voltage） 取样时间：10 cycles/second(total) 过载显示: " doFL " 显示值范围: 0-9999 digit（DCA/W(KW)） 0-9999999.999 digit(WH/(KWH)) RS-485传输速度: 19200/9600/4800/2400 selective RS-485通讯位址: "01"-"FF"（0-255） RS-485通信协议: Modbus RTU mode 温度系数: 50ppm/℃ (0-50℃) 显示幕:Bight Red LEDs high 10.16 mm(0.4") 参数设定方式: Touch switches 记忆方式: Non-volatile E²PROM memory 绝缘耐压能力:2KVac/1min.(input/output)（RS-485(Isolating)） 1600 Vdc (input/output) （RS-485(Isolating)） 使用环境条件: 0-50℃(20 to 90% RH non-condensed) 存放环境条件: 0-70℃(20 to 90% RH non-condensed) CE认证: EN 55022:1998/A1:2000 Class A EN 61000-3-2:2000 EN 61000-3-3:1995/A1:2001 EN 55024:1998/A1:2001
上传时间： 2013-11-20
上传用户：s363994250
Abstract: Many modern industrial, medical, and commercial applications require temperature measurements in the extended temperature rangewith accuracies of ±0.3°C or better, performed with reasonable cost and often with low power consumption. This article explains how platinumresistance temperature detectors (PRTDs) can perform measurements over wide temperature ranges of -200°C to +850°C, with absolute accuracyand repeatability better than ±0.3°C, when used with modern processors capable of resolving nonlinear mathematical equation quickly and costeffectively. This article is the second installment of a series on PRTDs. For the first installment, please read application note 4875, "High-Accuracy Temperature Measurements Call for Platinum Resistance Temperature Detectors (PRTDs) and Precision Delta-Sigma ADCs."
上传时间： 2013-11-06
上传用户：WMC_geophy
The data plane of the reference design consists of a configurable multi-channel XBERT modulethat generates and checks high-speed serial data transmitted and received by the MGTs. Eachchannel in the XBERT module consists of two MGTs (MGTA and MGTB), which physicallyoccupy one MGT tile in the Virtex-4 FPGA. Each MGT has its own pattern checker, but bothMGTs in a channel share the same pattern generator. Each channel can load a differentpattern. The MGT serial rate depends on the reference clock frequency and the internal PMAdivider settings. The reference design can be scaled anywhere from one channel (two MGTs)to twelve channels (twenty-four MGTs).
上传时间： 2013-12-25
上传用户：jkhjkh1982
Delta-sigma ADCs, with their high accuracy and high noiseimmunity, are ideal for directly measuring many typesof sensors. Nevertheless, input sampling currents canoverwhelm high source impedances or low-bandwidth,micropower signal conditioning circuits. The LTC®2484family of delta sigma converters solves this problem bybalancing the input currents, thussimplifying or eliminatingthe need for signal conditioning circuits.
上传时间： 2015-01-03
上传用户：潜水的三贡
The high defi nition multimedia interface (HDMI) is fastbecoming the de facto standard for passing digitalaudio and video data in home entertainment systems.This standard includes an I2C type bus called a displaydata channel (DDC) that is used to pass extended digitalinterface data (EDID) from the sinkdevice (such as adigital TV) to the source device (such as a digital A/Vreceiver). EDID includes vital information on the digitaldata formats that the sink device can accept. The HDMIspecifi cation requires that devices have less than 50pFof input capacitance on their DDC bus lines, which canbe very diffi cult to meet. The LTC®4300A’s capacitancebuffering feature allows devices to pass the HDMI DDCinput capacitance compliance test with ease.
上传时间： 2013-11-21
上传用户：tian126vip
This application note discusses a variety of approaches for interfacing analog signals to 5V powered systems. Synthesizing a "rail-to-rail" op amp and scaling techniques for A/D converters are covered. A voltage-to-frequency converter, applicable where high resolution is required, is also presented.
上传时间： 2013-10-12
上传用户：181992417
