A Design and Implementation of The Online Shopping System Abstract: Along with the development of the computer ,the database technique is widespread in the application of Internet, more and more , providing more thoughtful and humanized service for the large network customer. characteristic services have already become gradually the current as the application of Wed nowadays. This text studied a method of project which composed of characteristic page and dynamic state of technical customer according to the data connection rule, compared with some projects that adopt already on present nets, this project have the advantage of providing customers more simple ,reflective obvious meticulous use and so on..
标签： Implementation development Abstract Shopping
上传时间： 2014-12-04
上传用户：410805624
An Overview of Smart Card Security. The smart card, an intelligent token, is a credit card sized plastic card embedded with an integrated circuit chip. It provides not only memory capacity, but computational capability as well. The self-containment of smart card makes it resistant to attack as it does not need to depend upon potentially vulnerable external resources. Because of this characteristic, smart cards are often used in different applications which require strong security protection and authentication.
标签： card intelligent Overview Security
上传时间： 2017-09-25
上传用户：busterman
Cooperation is not a natural characteristic attributed to humans. The typical human horizon is focused on short-term gains, which might be due to our instinct-driven subconscious occupying a grander importance than we dare to admit [1]. Cooperating with other individuals or entities, however, usually means that short-term losses may translate into long-term gains – something history has proved to hold true but humans for some reason rarely ever understand.
标签： Communications Cooperative
上传时间： 2020-05-27
上传用户：shancjb
Many good textbooks exist on probability and random processes written at the under- graduate level to the research level. However, there is no one handy and ready book that explains most of the essential topics, such as random variables and most of their frequently used discrete and continuous probability distribution functions; moments, transformation, and convergences of random variables; characteristic and generating functions; estimation theory and the associated orthogonality principle; vector random variables; random processes and their autocovariance and cross-covariance functions; sta- tionarity concepts; and random processes through linear systems and the associated Wiener and Kalman filters.
标签： Probability Processes Random and
上传时间： 2020-05-31
上传用户：shancjb
基于TMS320F2812 光伏并网发电模拟装置PROTEL设计原理图+PCB+软件源码+WORD论文文档,硬件采用2层板设计，PROTEL99SE 设计的工程文件，包括完整的原理图和PCB文件，可以做为你的学习设计参考。 摘要：本文实现了一个基于TMS320F2812 DSP芯片的光伏并网发电模拟装置，采用直流稳压源和滑动变阻器来模拟光伏电池。通过TMS320F2812 DSP芯片ADC模块实时采样模拟电网电压的正弦参考信号、光伏电池输出电压、负载电压电流反馈信号等。经过数据处理后，用PWM模块产生实时的SPWM 波，控制MOSFET逆变全桥输出正弦波。本文用PI控制算法实现了输出信号对给定模拟电网电压的正弦参考信号的频率和相位跟踪，用恒定电压法实现了光伏电池最大功率点跟踪（MPPT），从而达到模拟并网的效果。另外本装置还实现了光伏电池输出欠压、负载过流保护功能以及光伏电池输出欠压、过流保护自恢复功能、声光报警功能、孤岛效应的检测、保护与自恢复功能。系统测试结果表明本设计完全满定设计要求。关键词：光伏并网，MPPT，DSP Photovoltaic Grid-connected generation simulator Zhangyuxin，Tantiancheng，Xiewuyang(College of Electrical Engineering, Chongqing University)Abstract: This paper presents a photovoltaic grid-connected generation simulator which is based on TMS320F2812 DSP, with a DC voltage source and a variable resistor to simulate the characteristic of photovoltaic cells. We use the internal AD converter to real-time sampling the referenced grid voltage signal, outputting voltage of photovoltaic, feedback outputting voltage and current signal. The PWM module generates SVPWM according to the calculation of the real-time sampling data, to control the full MOSFET inverter bridge output sine wave. We realized that the output voltage of the simulator can track the frequency and phase of the referenced grid voltage with PI regulation, and the maximum photovoltaic power tracking with constant voltage regulation, thereby achieved the purpose of grid-connected simulation. Additionally, this device has the over-voltage and over-current protection, audible and visual alarm, islanding detecting and protection, and it can recover automatically. The testing shows that our design is feasible.Keywords: Photovoltaic Grid-connected，MPPT，DSP 目录引言 11. 方案论证 11.1. 总体介绍 11.2. 光伏电池模拟装置 11.3. DC-AC逆变桥 11.4. MOSFET驱动电路方案 21.5. 逆变电路的变频控制方案 22. 理论分析与计算 22.1. SPWM产生 22.1.1. 规则采样法 22.1.2. SPWM 脉冲的计算公式 32.1.3. SPWM 脉冲计算公式中的参数计算 32.1.4. TMS320F2812 DSP控制器的事件管理单元 42.1.5. 软件设计方法 62.2. MPPT的控制方法与参数计算 72.3. 同频、同相的控制方法和参数计算 8
标签： tms320f2812 光伏 并网发电 模拟 protel pcb
上传时间： 2021-11-02
上传用户：ooaaooxx
