ble Logic Controller，可編程邏輯控制器，一種數(shù)字運算操作的電子系統(tǒng)，專為在工業(yè)環(huán)境應(yīng)用而設(shè)計的。它采用一類可編程的存儲器，用于其內(nèi)部存儲程序，執(zhí)行邏輯運算，順序控制，定時，計數(shù)與算術(shù)操作等面向用戶的指令，并通過數(shù)字或模擬式輸入/輸出控制各種類型的機械或生產(chǎn)過程。是工業(yè)控制的核心部分。 另外PLC還有以下幾個名稱： PLC = Power Line Communication，電力線通信，即我們俗稱的“電力線上網(wǎng)”。 PLC = Public Listed Co
標簽： 驅(qū)動器
上傳時間： 2018-06-27
上傳用戶：454545
我們編寫的程序由兩個主要方面組成 1 算法的集合就是將指令組織成程序來解決某個特定的問題 2 數(shù)據(jù)的集合算法在這些數(shù)據(jù)上操作以提供問題的解決方案 縱觀短暫的計算機發(fā)展史這兩個主要方面算法和數(shù)據(jù)一直保持不變發(fā)展演化的 是它們之間的關(guān)系就是所謂的程序設(shè)計方法programming paradigm 在過程化程序設(shè)計方法procedural programming 中一個問題可直接由一組算法來建 立模型例如公共圖書館的資料借閱/登記check out/check in 系統(tǒng)是由一系列過程表現(xiàn) 出來的其中兩個主要的過程是資料的借閱和登記這些數(shù)據(jù)被獨立存儲起來我們既可以 在某個全局位置上訪問這些數(shù)據(jù)或者把數(shù)據(jù)傳遞給過程以便它能夠訪問這些數(shù)據(jù)Fortran C 和 Pascal 是三種著名的過程語言C++也支持過程化程序設(shè)計單獨的過程如check_in() check_out() over_due() fine()等等都被稱為函數(shù)第三篇將集中討論C++對過程化程序 設(shè)計方法的支持尤其將重點討論函數(shù)函數(shù)模板和通用算法 在20 世紀70 年代程序設(shè)計的焦點從過程化程序設(shè)計方法轉(zhuǎn)移到了抽象數(shù)據(jù)類型 abstract data type 簡寫為ADT 的程序設(shè)計上現(xiàn)在通常稱之為基于對象(object based 的程序設(shè)計在基于對象的程序設(shè)計方法中我們通過一組數(shù)據(jù)抽象來建立問題的模型在 C++中我們把這些抽象稱為類class 例如在這種方法下圖書館資料借閱登記系統(tǒng)就 由類的對象實例比如書借閱者還書時間罰款等之間的相互作用表現(xiàn)出來以此表 示出圖書館的抽象概念與每個類相關(guān)的算法被稱為該類的公有接口public interface 數(shù) 據(jù)以私有形式被存儲在每個對象中對數(shù)據(jù)的訪問應(yīng)與一般的程序代碼隔離開來CLU Ada 和Modula-2 是三種支持抽象數(shù)據(jù)類型的程序設(shè)計語言第四篇將說明和討論C++對抽象數(shù)據(jù) 類型程序設(shè)計方法的支持 面向?qū)ο蟮某绦蛟O(shè)計方法通過繼承inheritance 機制和動態(tài)綁定dynamic binding 機 制擴展了抽象數(shù)據(jù)類型繼承機制是對現(xiàn)有實現(xiàn)代碼的重用動態(tài)綁定是指對現(xiàn)有的公有接 口的重用以前獨立的類型現(xiàn)在有了類型/子類型的特定關(guān)系一本書一盒錄像帶一段錄 音甚至孩子的寵物盡管它們有各自的借閱/登記方式但都可以成為圖書館的收藏資料 共享的公有接口和私有的數(shù)據(jù)都放在一個抽象類圖書館資料LibraryMaterial 中每個特 殊的圖書館資料類都從LibraryMaterial 抽象類繼承共享的行為它們只需要提供與自身行為相 關(guān)的算法和數(shù)據(jù)Simula Smalltalk 和Java 是三種支持面向?qū)ο蟪绦蛟O(shè)計方法的著名語言 第五篇將集中討論C++對面向?qū)ο蟪绦蛟O(shè)計方法的支持 C++是一種支持多種程序設(shè)計方法的語言雖然我們主要把它當作面向?qū)ο蟮恼Z言但 實際上它也提供對過程化的和基于對象的程序設(shè)計方法的支持這樣做的好處是對每個問題 都能夠提供最合適的解決方案事實上沒有一種程序設(shè)計方法能夠
上傳時間： 2019-01-30
上傳用戶：jizhi111
The concept of smart cities emerged few years ago as a new vision for urban development that aims to integrate multiple information and communication technology (ICT) solutions in a secure fashion to manage a city’s assets. Modern ICT infrastructure and e-services should fuel sustainable growth and quality of life, enabled by a wise and participative management of natural resources to be ensured by citizens and government. The need to build smart cities became a requirement that relies on urban development that should take charge of the new infrastructures for smart cities (broadband infrastructures, wireless sensor networks, Internet-based networked applications, open data and open platforms) and provide various smart services and enablers in various domains including healthcare, energy, education, environmental management, transportation, mobility and public safety.
上傳時間： 2020-05-25
上傳用戶：shancjb
The current methods of communications are becoming less relevant under today’s growing demand for and reliance on constant connectivity. Of decreasing relevance are the models of a single radio to perform a single task. The expansion of wireless access points among coffee shops, airports, malls, and other public arenas is opening up opportunities for new services and applications.
上傳時間： 2020-05-26
上傳用戶：shancjb
Multiple-Input Multiple-Output (MIMO) systems have recently been the subject of intensive consideration in modem wireless communications as they offer the potential of providing high capacity, thus unleashing a wide range of applications in the wireless domain. The main feature of MIMO systems is the use of space-time processing and Space-Time Codes (STCs). Among a variety of STCs, orthogonal Space-Time Block Codes (STBCs) have a much simpler decoding method, compared to other STCs
標簽： Orthogonal Space-Time Processing Complex
上傳時間： 2020-05-26
上傳用戶：shancjb
Optical communication technology has been extensively developed over the last 50 years, since the proposed idea by Kao and Hockham [1]. However, only during the last 15 years have the concepts of communication foundation, that is, the modulation and demodulation techniques, been applied. This is pos- sible due to processing signals using real and imaginary components in the baseband in the digital domain. The baseband signals can be recovered from the optical passband region using polarization and phase diversity tech- niques, as well as technology that was developed in the mid-1980s.
標簽： Transmission Processing Digital Optical
上傳時間： 2020-05-27
上傳用戶：shancjb
The General Packet Radio Service (GPRS) allows an end user to send and receive data in packet transfer mode within a public land mobile network (PLMN) without using a permanent connection between the mobile station (MS) and the external network during data transfer. This way, GPRS opti- mizes the use of network and radio resources (RRs) since, unlike circuit- switched mode, no connection between the MS and the external network is established when there is no data flow in progress. Thus, this RR optimiza- tion makes it possible for the operator to offer more attractive fees.
上傳時間： 2020-05-27
上傳用戶：shancjb
OSCILLATORS are key building blocks in integrated transceivers. In wired and wireless communication terminals, the receiver front-end selects, amplifies and converts the desired high-frequency signal to baseband. At baseband the signal can then be converted into the digital domain for further data processing and demodula- tion. The transmitter front-end converts an analog baseband signal to a suitable high- frequency signal that can be transmitted over the wired or wireless channel.
標簽： High-Frequency Oscillator Design
上傳時間： 2020-05-27
上傳用戶：shancjb
In this paper we revisit hybrid analog-digital precoding systems with emphasis on their modelling and radio-frequency (RF) losses, to realistically evaluate their benefits in 5G system implementations. For this, we decompose the analog beamforming networks (ABFN) as a bank of commonly used RF components and formulate realistic model constraints based on their S-parameters. Specifically, we concentrate on fully-connected ABFN (FC-ABFN) and Butler networks for implementing the discrete Fourier transform (DFT) in the RF domain. The results presented in this paper reveal that the performance and energy efficiency of hybrid precoding systems are severely affected, once practical factors are considered in the overall design. In this context, we also show that Butler RF networks are capable of providing better performances than FC-ABFN for systems with a large number of RF chains.
標簽： Analog-Digital Precoding Hybrid
上傳時間： 2020-05-27
上傳用戶：shancjb
Mobile telephone service (MTS) is a type of service where mobile radio tele- phones connect people to the public switched telephone system (PSTN), to other mobile telephones or to other communication systems (such as to the Internet).
標簽： Introduction Telephone Systems Mobile to
上傳時間： 2020-05-27
上傳用戶：shancjb
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