December 2007, San Jose, California: It seems a long time ago. I walked into a big networking company to head their small Power over Ethernet (PoE) applications team. Surprisingly, I hardly knew anything about PoE prior to that day, having been a switching-power conversion engineer almost all my life. But it seemed a great opportunity to widen my horizons. As you can see, one notable outcome of that seemingly illogical career choice five years ago is the book you hold in your hands today. I hope this small body of work goes on to prove worthy of your expectations and also of all the effort that went into it. Because, behind the scenes, there is a rather interesting story to relate—about its backdrop, intertwined with a small slice of modern PoE history, punctuated by a rather res- tive search for our roots and our true heroes, one that takes us back almost two centuries
上傳時間： 2020-06-07
上傳用戶：shancjb
With all the recent hype over radio frequency identification (RFID) and the requirements to implement it, you might think that RFID can turn water into wine, transform lead into gold, and cure the world’s diseases. You might also be worried that RFID will enable Big Brother to track your move- ments to within a foot of your location from a satellite five hundred miles up in space. The truth is, RFID can do none of these things. In this chapter, you find out the basics of what RFID is, what forces are dri- ving RFID as a replacement for the bar code in the marketplace, and what benefits RFID can offer
標簽： ForDummies_RFID_For_Dummies
上傳時間： 2020-06-08
上傳用戶：shancjb
To a quantum mechanic the whole universe is one godawful big interacting wavefunction ? but to the rest of us, it’s a world full of separate and distinguishable objects that hurt us when we kick them. At a few months of age, human children recognize objects, expect them to be permanent and move continuously, and display surprise when they aren’t or don’t. We associate visual, tactile, and in some cases audible and olfactory sensations with identifiable physical things. We’re hardwired to understand our environment as being composed of separable things with specific properties and locations. We understand the world in terms of what was where when.
上傳時間： 2020-06-08
上傳用戶：shancjb
Artificial Intelligence (AI) is a big field, and this is a big book. We have tried to explore the full breadth of the field, which encompasses logic, probability, and continuous mathematics; perception, reasoning, learning, and action; and everything from microelectronic devices to robotic planetary explorers. The book is also big because we go into some depth. The subtitle of this book is “A Modern Approach.” The intended meaning of this rather empty phrase is that we have tried to synthesize what is now known into a common frame- work, rather than trying to explain each subfield of AI in its own historical context. We apologize to those whose subfields are, as a result, less recognizable.
標簽： A-Modern-Approach Intelligence
上傳時間： 2020-06-10
上傳用戶：shancjb
前不久ARM正式宣布推出新款A(yù)RM8架構(gòu)的 Cortex-A50處理器系列產(chǎn)品，以此來擴大ARM在高性能與低功耗領(lǐng)域的領(lǐng)先地位，進一步搶占移動終端市場份額Cortex-A50是繼 Cortex-A15之后的又重量級產(chǎn)品，將會直接影響到主流PC市場的占有率。圍繞該話題，我們今天不妨總結(jié)一下近幾年來手機端較為主流的ARM處理器。以由高到低的方式來看，ARM處理器大體上可以排序為：Cortex-A57處理器、Cortex-A53處理器、Cortex-A15處理器、Cortex-A12處理器、Cortex-A9處理器、Cortex-A8處理器Cortex-A7處理器、Cortex-A5處理器、ARM11處理器、ARM9處理器、ARM7處理器，再往低的部分手機產(chǎn)品中基本已經(jīng)不再使用，這里就不再介紹。● Cortex-A57、A53處理器Cortex-A53、Cortex-A57兩款處理器屬于 Cortex-A50系列，首次采用64位ARM8架構(gòu)，意義重大，這也是ARM最近剛剛發(fā)布的兩款產(chǎn)品。Cortex-A57是ARM最先進、性能最高的應(yīng)用處理器，號稱可在同樣的功耗水平下達到當(dāng)今頂級智能手機性能的三倍；而 Cortex-A53是世界上能效最高、面積最小的64位處理器，同等性能下能效是當(dāng)今高端智能手機的三倍。這兩款處理器還可整合為 ARM big LITTLE（大小核心伴侶）處理器架構(gòu)，根據(jù)運算需求在兩者間進行切換，以結(jié)合高性能與高功耗效率的特點，兩個處理器是獨立運作的
標簽： arm
上傳時間： 2022-03-30
上傳用戶：默默
電學(xué)中的測量技術(shù)涉及范圍非常廣,電流測量在電學(xué)計量中占有非常重要的位置。如何精確地進行電流測量是精密測量的一大難題。傳統(tǒng)的電流檢測電路多采用運算放大芯片與片外電流檢測電路相結(jié)合的方式,電路集成度很低,需要較多的接口和資源才能完成對電路的檢測。本文把所有電路部分都集成在一塊芯片上,包括檢測電阻,運算放大器電路及模擬轉(zhuǎn)數(shù)字轉(zhuǎn)換電路,從而在電路內(nèi)部可以進行電流檢測,使電路更好的集成化。前置電路使用二級共源共柵結(jié)構(gòu)的運算放大器,減小溝道長度調(diào)制效應(yīng)造成的電流誤差。10位SAR ADC中采用電容驅(qū)動能力強的傳輸門保證了模數(shù)轉(zhuǎn)化器的有效精度。比較器模塊采用再生鎖存器與遲滯比較器作為基礎(chǔ)單元組合解決精密測量的問題。本設(shè)計可以作為嵌入芯片內(nèi)的一小部分而檢測芯片中的微小電流1mA~100mA,工作電壓在1.8v左右,電流檢測精度預(yù)期達到10uA的需求。The measurement technology in electricity involves a wide range,and current measurement plays a very important position in electrical measurement.How to accurately measure current is a big problem in precision measurement. The traditional current detecting circuit adopts the combination of the operational amplifier chip and theoff-chip current detecting circuit, The circuit integration is very low, and more interfaces and resources are needed tocomplete the circuit detection.This topic integrates all the circuit parts into one chip, including detection resistance, operational amplifier circuit andanalog to digital conversion circuit. Highly integrated circuit makes the external resources on the chip more intensive,so that current detection can be carried out inside the circuit, so that the circuit can be better integrated. Thefront-end circuit of this project uses two-stage cascade operational amplifier and cascade tube to reduce the currenterror caused by channel length modulation effect. In 10-bit SAR ADC, the transmission gate with strong capacitivedriving ability ensures the effective accuracy of the analog-to-digital converter. Comparator module uses regenerativelatch and hysteresis comparator as basic unit to solve the difficult problem of precision measurement. This topic can beused as a small part of the embedded chip to detect the micro-current in the chip 1 mA~100 mA, the working voltageis about 1.8v, and the current detection accuracy is expected to reach the requirement of 10 uA.
上傳時間： 2022-04-03
上傳用戶：
Android開發(fā)權(quán)威指南.rar 是一本學(xué)習(xí)Android書籍Big Nerd Ranch 是美國一家專業(yè)的移動開發(fā)技術(shù)培訓(xùn)機構(gòu)，本書主要以訓(xùn)練營的 5 天教學(xué)課程為基 礎(chǔ)，融合了兩位作者多年的心得體會，是一本完全面向?qū)崙?zhàn)的 Android 編程權(quán)威指南。全書共 37 章，詳細 介紹了 GeoQuiz、HelloMoon、DragAndDraw 等 8 個 Android 應(yīng)用。這些應(yīng)用的難易程度不一，最復(fù)雜的 CriminalIntent 應(yīng)用占用了 13 章的篇幅。通過這些精心設(shè)計的應(yīng)用，讀者可掌握很多重要的理論知識和開發(fā) 技巧，獲得最前沿的開發(fā)經(jīng)驗。
標簽： android
上傳時間： 2022-06-28
上傳用戶：
RK3399是瑞芯微推出的一款低功耗、高性能的應(yīng)用處理器芯片，該芯片基于Big.Little架構(gòu),即具有獨立的NEON協(xié)同處理器的雙核Cortex-A72及四核Cortex-A53組合架構(gòu)，主要應(yīng)用于計算機、個人互聯(lián)網(wǎng)移動設(shè)備、VR、廣告機等智能終端設(shè)備。RK3399內(nèi)置多個高性能硬件處理引擎，能夠支持多種格式的視頻解碼，如：4K*2K@60fps H.264/H.265/VP9，也支持1080P@30fps的H.264/MVC/VP8 以及高質(zhì)量的JPEG編解碼和圖像的前后處理器。寧遠電子科技最新研發(fā)的DLT3399A產(chǎn)品，搭建了最新android7.1 系統(tǒng)，2G 內(nèi)存，16G EMMC 存諸。DLT3399A產(chǎn)品為消費類電子、VR設(shè)備、人臉識別設(shè)備、車載控制、機器人、智能終端、MID、無線通訊、醫(yī)療設(shè)備、工業(yè)控制等行業(yè)產(chǎn)品的應(yīng)用開發(fā)而設(shè)計，超強的視頻處理能力，超高清視頻輸出優(yōu)勢，尤其適合做工業(yè)控制、廣告機和人臉識別設(shè)備等。DLT3399A其豐富的接口、精湛的設(shè)計，可供廣大企業(yè)用戶做產(chǎn)品使用。
上傳時間： 2022-07-25
上傳用戶：
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