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..
標簽： Implementation development Abstract Shopping
上傳時間： 2014-12-04
上傳用戶：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.
標簽： card intelligent Overview Security
上傳時間： 2017-09-25
上傳用戶：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.
標簽： Communications Cooperative
上傳時間： 2020-05-27
上傳用戶：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.
標簽： Probability Processes Random and
上傳時間： 2020-05-31
上傳用戶：shancjb
基于TMS320F2812 光伏并網(wǎng)發(fā)電模擬裝置PROTEL設(shè)計原理圖+PCB+軟件源碼+WORD論文文檔,硬件采用2層板設(shè)計，PROTEL99SE 設(shè)計的工程文件，包括完整的原理圖和PCB文件，可以做為你的學(xué)習(xí)設(shè)計參考。 摘要：本文實現(xiàn)了一個基于TMS320F2812 DSP芯片的光伏并網(wǎng)發(fā)電模擬裝置，采用直流穩(wěn)壓源和滑動變阻器來模擬光伏電池。通過TMS320F2812 DSP芯片ADC模塊實時采樣模擬電網(wǎng)電壓的正弦參考信號、光伏電池輸出電壓、負載電壓電流反饋信號等。經(jīng)過數(shù)據(jù)處理后，用PWM模塊產(chǎn)生實時的SPWM 波，控制MOSFET逆變?nèi)珮蜉敵稣也ā１疚挠肞I控制算法實現(xiàn)了輸出信號對給定模擬電網(wǎng)電壓的正弦參考信號的頻率和相位跟蹤，用恒定電壓法實現(xiàn)了光伏電池最大功率點跟蹤（MPPT），從而達到模擬并網(wǎng)的效果。另外本裝置還實現(xiàn)了光伏電池輸出欠壓、負載過流保護功能以及光伏電池輸出欠壓、過流保護自恢復(fù)功能、聲光報警功能、孤島效應(yīng)的檢測、保護與自恢復(fù)功能。系統(tǒng)測試結(jié)果表明本設(shè)計完全滿定設(shè)計要求。關(guān)鍵詞：光伏并網(wǎng)，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 目錄引言 11. 方案論證 11.1. 總體介紹 11.2. 光伏電池模擬裝置 11.3. DC-AC逆變橋 11.4. MOSFET驅(qū)動電路方案 21.5. 逆變電路的變頻控制方案 22. 理論分析與計算 22.1. SPWM產(chǎn)生 22.1.1. 規(guī)則采樣法 22.1.2. SPWM 脈沖的計算公式 32.1.3. SPWM 脈沖計算公式中的參數(shù)計算 32.1.4. TMS320F2812 DSP控制器的事件管理單元 42.1.5. 軟件設(shè)計方法 62.2. MPPT的控制方法與參數(shù)計算 72.3. 同頻、同相的控制方法和參數(shù)計算 8
標簽： tms320f2812 光伏 并網(wǎng)發(fā)電 模擬 protel pcb
上傳時間： 2021-11-02
上傳用戶：
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