The Internet of Things is considered to be the next big opportunity, and challenge, for the Internet engineering community, users of technology, companies and society as a whole. It involves connecting embedded devices such as sensors, home appliances, weather stations and even toys to Internet Protocol (IP) based networks. The number of IP-enabled embedded devices is increasing rapidly, and although hard to estimate, will surely outnumber the number of personal computers (PCs) and servers in the future. With the advances made over the past decade in microcontroller,low-power radio, battery and microelectronic technology, the trend in the industry is for smart embedded devices (called smart objects) to become IP-enabled, and an integral part of the latest services on the Internet. These services are no longer cyber, just including data created by humans, but are to become very connected to the physical world around us by including sensor data, the monitoring and control of machines, and other kinds of physical context. We call this latest frontier of the Internet, consisting of wireless low-power embedded devices, the Wireless Embedded Internet. Applications that this new frontier of the Internet enable are critical to the sustainability, efficiency and safety of society and include home and building automation, healthcare, energy efficiency, smart grids and environmental monitoring to name just a few.
标签： Embedded Internet Wireless 6LoWPAN The
上传时间： 2020-05-26
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The field of digital communication has evolved rapidly in the past few decades, with commercial applications proliferating in wireline communi- cation networks (e.g., digital subscriber loop, cable, fiber optics), wireless communication (e.g., cell phones and wireless local area networks), and stor- age media (e.g., compact discs, hard drives). The typical undergraduate and graduate student is drawn to the field because of these applications, but is often intimidated by the mathematical background necessary to understand communication theory.
标签： Communication Fundamentals Digital of
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FPGA HArd Ethercat Master
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The ever-increasing demand for private and sensitive data transmission over wireless net- works has made security a crucial concern in the current and future large-scale, dynamic, and heterogeneous wireless communication systems. To address this challenge, computer scientists and engineers have tried hard to continuously come up with improved crypto- graphic algorithms. But typically we do not need to wait too long to find an efficient way to crack these algorithms. With the rapid progress of computational devices, the current cryptographic methods are already becoming more unreliable. In recent years, wireless re- searchers have sought a new security paradigm termed physical layer security. Unlike the traditional cryptographic approach which ignores the effect of the wireless medium, physi- cal layer security exploits the important characteristics of wireless channel, such as fading, interference, and noise, for improving the communication security against eavesdropping attacks. This new security paradigm is expected to complement and significantly increase the overall communication security of future wireless networks.
标签： Communications Physical Security Wireless Layer in
上传时间： 2020-05-31
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This book was born from the perception that there is much more to spectrum use and sharing than one sees reflected in publications, whether academic, commercial or political. the former – in good research style – tend towards reductionism and concentrate on specific, detailed aspects. commercial publications tend to empha- size the positive aspects and they tend to put promise above practice. Given the ever increasing pace of technology development and recent successes of new wireless technologies, some pundits predict large-scale spectrum scarcity, potentially lead- ing to economic catastrophe. Although economic theory has a hard time explaining recent events that shook the world economy, the notion of spectrum scarcity is intui- tively acceptable, even if not correct or immediately relevant.
上传时间： 2020-06-01
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The serious study of the practice of how to determine the appropriate content of a specification is a seldom-appreciated pastime. Those who have the responsibility to design a product would prefer a greater degree of freedom than permitted by the con- tent of a specification. Many of those who would manage those who would design a product would prefer to allocate all of the project funding and schedule to what they consider more productive labor. These are the attitudes, of course, that doom a project to defeat but they are hard to counter no matter how many times repeated by design engineers and managers. A system engineer who has survived a few of these experiences over a long career may retire and forget the past but we have an endur- ing obligation to work toward changing these attitudes while trying to offer younger system engineers a pathway toward a more sure success in requirements analysis and specification publishing.
标签： Requirements Analysis System
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Machine learning is a broad and fascinating field. Even today, machine learning technology runs a substantial part of your life, often without you knowing it. Any plausible approach to artifi- cial intelligence must involve learning, at some level, if for no other reason than it’s hard to call a system intelligent if it cannot learn. Machine learning is also fascinating in its own right for the philo- sophical questions it raises about what it means to learn and succeed at tasks.
标签： Learning Machine Course in
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全志A20核心板配套开发底板Cadence原理图+ Pads2005格式PCB文件+转换后的AD格式原理图PCB文件：A20_DVK1_BASE_V16_Altium_Designer15.PcbDocA20_DVK1_BASE_V16_BOM_20151015.xlsxA20_DVK1_BASE_V16_Gerber制板文件.rarA20_DVK1_BASE_V16_PADS2005_PCB30.pcbA20_DVK1_BASE_V16_PADS2005_PCB_ASCII.PcbDocA20_DVK1_BASE_V16_PADS9.5.pcba20_dvk1_base_v16_SCH_20151015.pdfA20_DVK1_BASE_V16_元件位置查找图_20151102.pdfA20_DVK1_BASE_V16_原理图_OrCAD16.5.DSNA20_DVK1_BASE_V16_导出到AD格式的原理图和PCBA20_DVK1_BASE_V16_导出到AD格式的原理图和PCB.rarA20_DVK1_BASE_V16_顶层元件编号丝印图_20151102.pdfA20_DVK1_BASE_V16_顶层元件规格丝印图_20151102.pdf主要器件如下：Library Component Count : 58Name Description----------------------------------------------------------------------------------------------------ANTBATTERY_1BEAD CAPCAP NP 贴片电容,Y5V,6.3V,2.2uF,+80%-20%,0603CAP NP_2_Dup1 X5RCAP NP_Dup2 0402 1uF X5R 6.3V +/-10%CAP NP_Dup3 0402 1uF X5R 6.3V +/-10%CAPACITOR CAPACITOR POLCON1 CON12 CON3 CON4 CON50 CON6CON6A CONNECTOR45X4 C_Generic DB15-VGA_0 DIODE DIODE DUAL SERIESFM25CL64 FR9886SPGTR FUSEHOLDER_0 HDMI19_PLUG HEADER 2 INDUCTOR/SMINDUCTOR_4 C4K-2.5HINDUCTOR_Dup2 INDUCTOR_Dup3 IRM-2638LED_0M93C46_0 MINI USB-B_6 MODULE_CAM_PA0505 PH163539 PLAUSB-AF5P-WSMT_0 PUSHBUTTON_TSKB-2L_0PowerJACK R1 0805 R1_0805 RES2X4RESISTOR RESISTOR_Dup1 RESISTOR_Dup2 RESISTOR_V RJ45_8PGR_Generic S9013SMD_Dup2 SD_MMC_CARD2_0 TP_5 TestPoint_3TitleBlock_Gongjun USBPORT2 USB_WIFI_0 XC6204VZ_3 LDO 3.3V 300mA( SOT-25 )rRClamp0524P
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移动机器人路径规划尤其是未知环境下机器人路径规划是机器人技术中的一个重要研究领域，得到了很多研究者的关注，并取得了一系列重要成果。目前已存在许多用来解决该问题的优化算法，但是此类问题属于N-Hard问题，寻求更佳的算法就成为该领域的一个研究热点。为此，根据机器人路径规划算法的研究现状和向智能化，仿生化发展的趋势，研究了一种基于图的机器人路径规划蚂蚁优化算法。算法首先用栅格法对机器人的工作空间进行建模，并用一个状态矩阵表示其状态，由此构造出一个连通图，由一组蚂蚁在图上模拟蚂蚁的觅食行为，从而得到避碰的优化路径。最后，借鉴分枝随机过程和生灭过程的理论知识，用概率的方法从理论上对该算法的收敛性进行了分析，在此基础上，结合计算机仿真结果，证实了本文提出的算法的有效性和收敛性。迄今为止，对于未知环境下机器人路径规划，人们已经探索出了许多有效的求解方法诸如虚拟力场法、基于学习或Q学习的规划方法、滚动窗口规划方法、非启发式方法及各类定位、导航方法等等。近年来，不少学者用改进的遗传算法、神经网络、随机树、蚁群算法等方法对未知环境下机器人路径进行了规划机器人路径规划算法向智能化、仿生化发展是一个明显的趋势.由于已有算法不同程度的存在一定局限性，诸如搜索空间大、算法复杂、效率不高等，尤其对于未知环境，不少路径规划算法的复杂度较高，甚至无法求解，根据日前的研究现状和不足，本文提出了一种用于解决未知环境下机器人路径规划的基于图的蚂蚁算法，理论分析和实验结果都证明了本文算法的有效性和收敛性本课题研究的主要内容本文在用概格法对机器人的工作空间进行建模的基础上，用一个状态矩阵表示其状态，由此构造一个连通图，由一组蚂蚊在图上模拟蚂蚁的觅食行为，从而得到避碰的优化路径并借鉴分枝随机过程和生灭过程的理论知识用概率的方法从理论上对该算法的收敛性进行了分析，结合计算机仿真，证明了本文算法的有效性和收敛性
上传时间： 2022-03-10
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反激式开关电源变压器设计的详细步骤85W反激变压器设计的详细步骤 1. 确定电源规格. 1).输入电压范围Vin=90—265Vac; 2).输出电压/负载电流:Vout1=42V/2A, Pout=84W 3).转换的效率=0.80 Pin=84/0.8=105W 2. 工作频率，匝比, 最低输入电压和最大占空比确定. Ｖmos*0.8>Vinmax+n(Vo+Vf)600*0.8>373+n(42+1)得n<2.5Vd*0.8>Vinmax/n+Vo400*0.8>373/n+42得n>1.34 所以n取1.6最低输入电压Vinmin=√[(Vacmin√2)* (Vacmin√2)-2Pin(T/2-tc)/Cin=(90√2*90√2-2*105*(20/2-3)/0.00015=80V取:工作频率fosc=60KHz, 最大占空比Dmax=n(Vo+Vf)/[n(Vo+Vf)+Vinmin]= 1.6(42+1)/[1.6(42+1)+80]=0.45 Ton(max)=1/f*Dmax=0.45/60000=7.5us 3. 变压器初级峰值电流的计算. Iin-avg=1/3Pin/Vinmin=1/3*105/80=0.4AΔIp1=2Iin-avg/D=2*0.4/0.45=1.78AIpk1=Pout/?/Vinmin*D+ΔIp1=84/0.8/80/0.45=2.79A 4. 变压器初级电感量的计算. 由式子Vdc=Lp*dip/dt,得: Lp= Vinmin*Ton(max)/ΔIp1 =80*0.0000075/1.78 =337uH 取Lp=337 uH 5.变压器铁芯的选择. 根据式子Aw*Ae=Pt*1000000/[2*ko*kc*fosc*Bm*j*?],其中: Pt(标称输出功率)= Pout=84W Ko(窗口的铜填充系数)=0.4 Kc(磁芯填充系数)=1(对于铁氧体), 变压器磁通密度Bm=1500Gs j(电流密度): j=4A/mm2;Aw*Ae=84*1000000/[2*0.4*1*60*103*1500Gs*4*0.80]=0.7cm4 考虑到绕线空间,选择窗口面积大的磁芯,查表: ER40/45铁氧体磁芯的有效截面积Ae=1.51cm2 ER40/45的功率容量乘积为 Ap = 3.7cm4 >0.7cm4 故选择ER40/45铁氧体磁芯. 6.变压器初级匝数 1).由Np=Vinmin*Ton/[Ae*Bm],得: Np=80*7.5*10n-6/[1.52*10n-4*0.15] =26.31 取 Np =27T 7. 变压器次级匝数的计算. Ns1(42v)=Np/n=27/1.6=16.875 取Ns1 = 17T Ns2(15v)=(15+1)* Ns1/(42+1)=6.3T 取Ns2 = 7T
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