无线电力传输外文文献翻译
无线电能传输
Frequency dependence of magnetic flux profile in the presence of metamaterials for wireless powertransferBoopalan GSchool of Electronics EngineeringVIT UniversityVellore, Tamil Nadu, Indiaboopalan@vit.ac.inSubramaniam C K School of Advance Sciences VIT University Vellore, Tamil Nadu, India subramaniam@vit.ac.inAbstract— We discuss the change in the magnetic flux profile by introducing a negative refractive index material (metamaterial) in between the source and receiver. The environment parameters, ε and μ , has a significant effect on the propagation of electromagnetic wave. The behavior of Transverse Magnetic (TM) wave when the medium in the path of propagation is changed to negative permittivity and permeability is simulated and discussed. The effect of size, shape and anisotrophy of the metamaterials, for near-field regions, on the magnetic flux density has been studied using finite element analysis. An enhancement in the magnetic flux density when a metamaterial is introduced in between the source and receiver was observed. The results show that the static and quasi-static behavior of the system is same.Keywords—metamaterials, quasi static, magnetic flux transverse magneticI.I NTRODUCTIONThe idea of charging on the go is an exciting option for various high power applications like Electric Vehicle. Wireless power charging can be done by radiative or non-radiative processes. Use of microwave and optical frequencies falls into the radiative category while non-radiative process refers to the near-field domain. This concept was put forward by Nikola Tesla when he invented an apparatus for transmitting electrical energy wirelessly [1]. Later, with the advent of microwave transmission technology in 1960’s researchers dreamed power transfer from satellite space station to earth [2]. For short distances inductive coupling is very convenient [3-4]. The enhancement in coupling efficiency is obtained by replacing coils with resonators [5-7]. The efficiency can further be improved by introducing a negative refractive index material between the source and the receiver [8-12]. The negative refractive index material or metamaterial has the unique property of enhancing the evanescent as well as non-evanescent waves [10].In this paper we present the magnetic flux density variations for quasi-static scenarios when a metamaterial is introduced in between the source and the receiver. The model used for simulation is a 2-dimensional one as we are interested only in the profile in that direction which is in the direction of propagation.II.T HEORYOur system consists of a source, receiver and a metamaterial as shown in fig. 1. The source is a circular loop of radius ‘a’ located in free space. The receiver is a point of interest ‘P’ where the magnetic flux density enhancement is observed. The metamaterial in between the source and the receiving point is a rectangular block which enhances the magnetic flux density at the point ‘P’. The transmitter is a single turn coil carrying current ‘I’ which in turn generates the magnetic field H in the surrounding medium. The magnetic field H at a distance ‘z’ from the center of the coil is given byI(1)The coil is fed with a current of ‘I’ amperes as given by the equation belowI . (2)Fig. 1. Schematic of Wireless Power transferyxzwhere, ‘J’ is the current density and ‘ds’ is the vector component perpendicular to the cross section of the circular coil. Then the applied potential V related to the current density J is given by the equationJ σVπ(3)where ‘σ’ is the conductivity of the coil and ‘a’ is the radiusof the coil.The direction of propagation is ‘z’, towards the point Pin fig. 1. To enhance the flux density the metamaterials of optimized dimension is placed in between the source and the receiver at a distance ‘z/2’ from the center of the transmitter coil as shown in figure 1. The metamaterial is one whose permittivity ε and permeability μ is negative. The materials can be classified on the values of εand μ as dielectric, plasmas, ferri-magnetic or metamaterial [11]. These parameters also constitute the propagation of electromagnetic waves in matter. Since the permittivity and permeability are negative for the metamaterial the refractive index also becomes negative as explained below. The refractive index is related to relative permittivity and relative permeability as mentioned belowε μ(4)If εr is -1 and μr is -1 then substituting e-iπ for -1 in the above equation gives refractive index as -1.We can solve the problem using FDTD (Finite Difference Time Domain) or the FEM (Finite Element Method). In both cases, the Maxwell equations are solved by dividing the solution region into nodes or elements considering suitable boundary conditions. We have used COMSOL Multiphysics, an FEM based tool for our simulation. The governing equation for quasi static situation is given byε (5)The magnetic flux density related to the magnetic potential and magnetic field intensity are given byμ (6)III.SIMULATIONA.ModelThe transmitter is a circular loop of radius 400mm excited with a current of 0.1 A. The coil is made up of copper of radius 1mm. From fig. 1 we can clearly see the structure of the system is symmetry and we are interested in the direction of propagation (z-direction). So it is sufficientto choose a 2D axisymmetry model for simulation. The metamaterial considered is anisotropic and characterised by uniaxial permittivity and permeability tensors as shown in equation belowε 000ε 000ε(7a)μ000μ00μ(7b)The distance between the source and the receiver is at a distance of 500mm. The magnetic flux density between the source and the receiving point of interest without the metamaterial is computed analytically and found to be be 3.87 × 10-8 Tesla. This scenario is simulated using COMSOL and found to be 3.74 × 10-8 Tesla.B.Results and DiscussionsThe propagation region can be subdivided into near field and far-field. In the far field region the efficiency is related to absorption and scattering by the environment. Also at high power electromagnetic interference becomes a critical issue. In reality propagation can occur by a simple radiative process. The radiative efficiency is reduced by losses due to absorption and scattering by the environment. At high intensities we will also have to deal with electromagnetic interference. In the near field, E/H ratio can be made negligible, thereby not causing any harm to biological and other objects in the vicinity. This in turn becomes a trade-off between the environmental benefits versus distance and efficiency of propagation. The propagation efficiency can be increased by introducing metamaterial in the medium between the source and receiver [8, 12].Fig. 2 shown below gives the magnetic flux density with when the transmitter coil is excited at a frequency ofFig. 2. Magnetic flux density (Tesla) with and without theNIM10 MHz without and with the metamaterial. It is clearly seen from the figure that there is an increase in the magnetic flux density when the metamaterial is introduced. Y. Urzhumov et al., [8] have also observed enhancement of transmission of TM polarized wave ie. magnetic field normal to propagation direction. Fig. 3 shows the relation between the size of the metamaterial and magnetic flux density. As the size of the material is increased radially in steps of 10mm we get a peak at a specific dimension. The same is observed when the material size is varied axially as seen in fig. 3. Similarly the distance between the material and receiver, size of the material, anisotrophy characteristics places a major role in enhancing the flux density [12]. Fig. 4 shows the magnetic flux density measured when the degree of anisotrophy in the direction of propagation εrzz /μrzz are varied from -1 to 1 in steps of 0.1. From the graph we can conclude that the magnetic flux density is high when εrzz and μrzz are -1.Y. Urzhumov et al., [8] suggests that the transverse wave propogation properties of a metamaterial slab of thickness ‘d’ and anisotropy ‘αTE ‘ are indistinguishable due to the invariance of the Maxwells equation, with respect to the coordinate transformation. This simply states that the metamaterial slab thickness can be reduced without effective change in performance. This is possible if the magnetic loss tangent is kept constant while increasing the negative real part of ‘μ‘.Fig. 5 shows the magnetic flux density is almost same from dc to 20 MHz. This gives an impression that the static and the quasi static behaviour of the system is same. This system can be used for High frequency RFID system (13.56 MHz) for enhancing the range and act as a power soure for charging the wireless devices in the Near-field regime. G. Shvet et al. [13], state that, for a single split ring resonator, SSR, of a metamaterial, the effective permeability approximately isμeff = 1 - F ω2 / ω2 – ωM 2 - i ωЃ andЄeff = 1 - (ωp 2 – ωE 2)/ ω2 – ωE 2 + i ωЃ (8)where F is the fractional area of a unit cell occupied by the SRR, ωM is the magnetic resonance frequency, and Ѓ, is the resistive loss coefficient, ωp is the characteristic ‘plasma’ frequency and ωE is the cut-wire resonance frequency. The filling factor F is typically kept small to avoid strong interaction between adjacent unit cells. Developing a metamaterial may require finding a resonant structure that has adjacent electric and magnetic resonances.For a periodic structure the effective permeability will reduce to [14]μ eff = μo [ 1 - (0.47)2 / { 1 – (1.05)2 / f 2 GHz } ] (9)where Єeff = 1.8 Єo . Here it is possible to show that a complex NIM structure can be equivalent to a uniform medium. The effective (Єeff - μeff ) of the medium will provide the width of the band around resonance. Here the losses are ignored, but from practical point it has a major impact. At the resonance, a very strong current is circulated in the loops and generates a considerable conduction loss.00.20.40.60.811.2100200M a g n e t i c f l u x d e n s i t y (×10-7) , T e s l aSize of the block increased in steps of 10mm in axial/radial direction, mmaxial radial00.20.40.60.811.2-2-112M a g n e t i c f l u x d e n s i t y (×10-7), T e s l aDegree of anisotrophy1.061.081.11.121.141.16-10102030M a g n e t i c f l u x d e n s i t y (×10-7), T e s l aFrequency, MHzFig. 3. Variation of magnetic flux density with block size(increased in steps of 10mm in axial/radial direction). Fig. 4. Degree of anisotrophy in z-direction varied from -1 to 1Fig. 5: Magnetic flux density variation from dc to 20 MHzThese are the issues that have to be resolved for practical purposes.IV.CONCLUSIONThere is an enhancement in the magnetic flux density when a metamaterial is introduced in between the source and receiver. This enhancement depends on the size, shape and anisotropy characteristics of the material. The above result implies that the static and quasi-static behavior of the system are same. Thus, the metamaterial can be used in between the source and receiver to enhance the range, which in turn increase the efficiency. It is also possible to further enhance the range if the source can be replaced with a resonator instead of the circular coil [6, 7]. This has immense possibility of application in high power energy transfer like electric vehicle wireless charging. An experimental setup is being fabricated and the results will be discussed in future. We are also looking at micro and nano-array architecture for the negative refractive index material. Preliminary results have been discussed elsewhere [15].A CKNOWLEDGMENTAuthors would like to thank the chancellor of VIT University for providing the encouragement and facilities to perform this work.R EFERENCES[1] N. Tesla, Apparatus for transmitting electrical energy, US patentnumber 1,119,732, December 1914.[2] W.C. Brown, “The history of power transmission by radio waves,”IEEE Trans. Microwave Theory Tech., vol. 32, pp.1230-1242, Sept.1984.[3] James O. McSpadden, John C. Mankins, “Space solar powerprograms and Microwave Wireless Power Transmission Technology”, IEEE Microwave Magazine, pp. 46-57, Dec. 2002.[4] A. Esser, H.-C. Skudelny, ”A new approach to Power supplies forRobots”, IEEE Trans. Industry Appl. Vol. 27, pp. 872-875, Oct. 1991. [5] J. Hirai, T.-W. Kim, A. Kawamura, “Wireless Transmission of Powerand Information for Cableless Linear Motor Drive”, IEEE Trans.Power Electron. vol. 15, pp. 21-27, Jan. 2000.[6] Andre Kurs, Aristeidis Karalis, Robert Moffatt, J.D. Joannopoulos,Peter Fisher, Marin Soljacic, “Wireless Power Transfer via StronglyCoupled Magnetic Resonances”, Science vol. 317, pp. 83-86, July 2007.[7] Aristeidis Karalis, J.D. Joannopoulos, Marin Soljacic, “Efficientwireless non-radiative mid-range energy transfer,” Annals of Physics,vol. 323, pp. 34-48, 2008.[8] Y. Urzhumov, D. R. Smith , “Metamaterial-enhanced couplingbetween magnetic dipoles for efficient wireless power transfer,”Physical Review B, vol. 83, 205114-1 to 205114-10, 2011.[9] B. Wang, K.H. Teo, T. Nishino, W. Yerazunius, J. Barnwell, J.Zhang, “Wireless Power Transfer with Metamaterials,” EuropeanConference on Antennas and Propagation (EuCAP 2011), CP03.3 (Rome, Italy), April 11-15, 2011.[10] J B Pendry, “Negative Refraction Makes a Perfect Lens”, PhysicsReview Letters, vol. 85, pp. 3966 – 3969, 2000.[11] C. Caloz, T. Itoh, “Electromagnetic metamaterials: Transmission linetheory and microwave applications”, Wiley-Interscience, 2006.[12] G. Boopalan and C.K. Subramaniam, “Study of Radiation FieldEffects in the presence of metamaterials”, presented at 7thInternational Conference on Materials for Advanced Technologies, ICMAT 2013, Singapore, pp. 176, 30th June to 5th July 2013.[13] G. Shvets and Y. Urzhumov, “Negative index meta-materials basedon two-dimensional metallic structures”, J. Opt. A: Pure Appl. Opt., vol. 8, pp. S122–S130, 2006.[14] H. Mosallaei and K. Sarabandi, A Novel Resonant Metallo-DielectricStructure for Design of High Performance Є - μ Meta-Materials, IEEE Antennas and Propagation Soc. International Symp., pp. 316-319, 2005.[15] G. Boopalan and C.K. Subramaniam, “A simulation study on theproperty of micro-arrayed negative refractive index material for the energy transfer”, Technical Proceedings of the 2013 NSTI Nanotechnology conference and Expo, NSTI-Nanotech 2013, pp.536-539, 12th May to 16th May 2013.。
电力系统毕业论文中英文外文文献翻译精选全文完整版
可编辑修改精选全文完整版电力系统电力系统介绍随着电力工业的增加，与用于生成和处置现今大规模电能消费的电力生产、传输、分派系统相关的经济、工程问题也随之增多。
这些系统组成了一个完整的电力系统。
应该着重提到的是生成电能的工业，它不同凡响的地方在于其产品应按顾客要求即需即用。
生成电的能源以煤、石油，或水库和湖泊中水的形式贮存起来，以备以后所有需。
但这并非会降低用户对发电机容量的需求。
显然，对电力系统而言服务的持续性相当重要。
没有哪一种服务能完全幸免可能显现的失误，而系统的本钱明显依托于其稳固性。
因此，必需在稳固性与本钱之间找到平稳点，而最终的选择应是负载大小、特点、可能显现中断的缘故、用户要求等的综合表现。
但是，网络靠得住性的增加是通过应用必然数量的生成单元和在发电站港湾各分区间和在国内、国际电网传输线路中利用自动断路器得以实现的。
事实上大型系统包括众多的发电站和由高容量传输线路连接的负载。
如此，在不中断整体服务的前提下能够停止单个发电单元或一套输电线路的运作。
现此生成和传输电力最普遍的系统是三相系统。
相关于其他交流系统而言，它具有简便、节能的优势。
尤其是在特定导体间电压、传输功率、传输距离和线耗的情形下，三相系统所需铜或铝仅为单相系统的75%。
三相系统另一个重要优势是三相电机比单相电机效率更高。
大规模电力生产的能源有：1.从常规燃料（煤、石油或天然气）、城市废料燃烧或核燃料应用中取得的蒸汽；2.水；3.石油中的柴油动力。
其他可能的能源有太阳能、风能、潮汐能等，但没有一种超越了试点发电站时期。
在大型蒸汽发电站中，蒸汽中的热能通过涡轮轮转换为功。
涡轮必需包括安装在轴承上并封锁于汽缸中的轴或转子。
转子由汽缸周围喷嘴喷射出的蒸汽流带动而平稳地转动。
蒸汽流撞击轴上的叶片。
中央电站采纳冷凝涡轮，即蒸汽在离开涡轮后会通过一冷凝器。
冷凝器通过其导管中大量冷水的循环来达到冷凝的成效，从而提高蒸汽的膨胀率、后继效率及涡轮的输出功率。
电的传输英语作文
电的传输英语作文Electricity is the lifeblood of modern society, powering our homes, industries, and cities. It is transmitted througha vast network of power lines and transformers, ensuring that every corner of our world is connected to this vital energy source.The process of electricity transmission begins at power stations, where it is generated from various sources such as coal, nuclear, or renewable energy. Once produced, the electricity is stepped up to high voltages using transformers to reduce energy loss during transmission.As the high-voltage electricity travels through the power lines, it encounters various challenges, including resistance and environmental factors. Engineers and technicians work tirelessly to maintain the stability and efficiency of the transmission system.Upon reaching its destination, the electricity is stepped down to safer voltages for distribution to homes and businesses. This process is crucial, as it ensures that the electricity is both safe and accessible to the end-user.The transmission of electricity is not without its environmental impacts, however. The infrastructure requiredfor transmission can disrupt landscapes and wildlife habitats. As a result, there is a growing focus on developing moresustainable and efficient transmission methods.In conclusion, the transmission of electricity is a complex and essential process that underpins our daily lives. As we continue to innovate and improve our transmission technologies, we must also consider the environmental implications and strive for a more sustainable future.。
文献检索无线电力传输地应用
题目：无线电力传输的应用The use of wireless power transmission一、背景知识：1、现代的有线电路传输虽然取得了巨大的发展与成就，但是其消耗了大量的线材，无论是橡胶、塑料抑或铜、锡等金属，浪费了社会资源、增加环境污染，不利于可持续发展的理念，而且其占用人类生活空间，给城市布局规划等造成巨大的不便。
2、国家坚持走可持续发展的科学发展观，坚持充分的利用现有的人类资源，建设环保型生态环境国家，并且国家设立了国家环保总局，统一管理我国的环保工作，以及一些有关生态、环境保护的法律。
在这种形势下，无线电力传输是很受欢迎的一种输电方式，它的实现将给人们生活带来革命性的变化，因此将迎来巨大的发展机遇。
二、课题分析: 人类追逐自由的本能，在现实面前屡屡受挫。
自从广泛使用电能以来，许多人都为了那些电器拖着的长长电线而绞尽脑汁，但无线供电却一直只能作为一个在前方远远招手的梦想。
现在，我们也许看到了一线曙光。
但要使无线电力传输在我们的日常生活当中得以广泛使用，我们应该解决什么样的问题，其主要的瓶颈在什么地方，如何才能解决无线电力传输的使用问题，这是我们首先要了解的知识。
进而可以从以下两方面考虑：1、当前无线电力传输的利用现状，特别是其在使用当中的具体情况，目前科学技术有限的条件下，无线传输领域在哪些方面有比较成熟的应用。
2、除了实用理论、技术方面，还应关注我国政府对此类无线电力传输技术的管理政策，同时希望了解：该项事业在拥有巨大社会效益的同时，是否能实现较好的经济效益，找到国内外典型的应用实例。
三、希望通过检索解决的问题：1、希望了解无线电力传输的历史发展及应用，相应的应用手段有哪些？目前比较可行的方法是什么？政府是否支持其发展应用？找一些专家分析和说明各方面问题的案例；2、希望了解我国在电力传输安全应用方面的法律规定，经济可行性。
国内外优秀环保组织的宗旨、主要活动介绍，先进经验的学习。
通过无线电传播英语作文
Growing up in a small town, the world outside my immediate surroundings felt distant and unreachable. But there was one magical device that bridged the gap between my little world and the vast universe of knowledge and culture: the radio. It was through the airwaves that I first encountered the English language, and it was a journey of discovery that continues to shape my life.The first time I heard English spoken fluently was on a latenight radio program. The host was discussing a book, their words flowing like a river, smooth and enchanting. I was captivated. The language was so different from my native tongue, with its unique rhythm and melody. It was like listening to a song, but one with meaning and depth. I knew right then that I wanted to learn this language, to understand the stories and ideas it carried.My journey with English began with the radio. Every day, I would tune in to various programs, trying to grasp the essence of the language. I started with simple phrases and gradually moved on to more complex sentences. The radio was my tutor, my companion, and my inspiration. It was through the radio that I learned about different cultures, histories, and perspectives, all through the medium of English.One of the most significant moments in my learning journey was when I started listening to English news broadcasts. It was a challenge at first, as the speed and accent were quite different from what I was used to. But with persistence and practice, I began to understand the gist of the news. It was exhilarating to be able to follow global events and understand theworld beyond my town.The radio also introduced me to English music. The lyrics were a treasure trove of vocabulary and idiomatic expressions. I would listen to the songs repeatedly, trying to decipher the meaning behind the words. It was a fun and engaging way to learn the language. Moreover, the music helped me appreciate the beauty and expressiveness of English.As I became more comfortable with English, I started participating in radio contests and quizzes. It was a thrilling experience to interact with the hosts and other listeners in English. The feedback and encouragement I received boosted my confidence and motivated me to keep improving.The radio also played a crucial role in preparing me for English exams. I would listen to educational programs that focused on grammar, vocabulary, and pronunciation. The explanations and examples provided by the experts were invaluable in honing my language skills.In addition to learning English, the radio also exposed me to other languages and dialects. It broadened my understanding of linguistic diversity and the importance of communication in connecting people from different backgrounds.Today, as a high school student, I am grateful for the role the radio played in my language learning journey. It opened up a world of opportunities and possibilities. The radio taught me that learning a language is not just about memorizing words and grammar rules its about immersing oneselfin the culture, history, and spirit of the language.The radio also instilled in me the importance of curiosity and perseverance. It showed me that learning is a lifelong journey, and that there is always more to explore and understand. The radio was my first step into the world of English, and it continues to inspire me to keep learning and growing.In conclusion, the radio was a powerful tool in my English learning journey. It was more than just a medium for entertainment it was a gateway to knowledge, understanding, and selfimprovement. As I continue to learn and grow, I will always cherish the memories and lessons from my time with the radio. It was through the airwaves that I discovered the beauty and power of the English language, and it will always hold a special place in my heart.。
通信外文翻译外文文献英文文献及译文
通信外文翻译外文文献英文文献及译文Communication SystemA generalized communication system has the following components:(a) Information Source. This produces a message which may be written or spoken words, or some form of data.(b) Transmitter. The transmitter converts the message into a signal, the form of which is suitable for transmission over the communication channel.(c) Communication Channel. The communication channel is the medium used transmit the signal, from the transmitter to the receiver. The channel may be a radio link or a direct wire connection.(d) Receiver. The receiver can be thought of as the inverse of the transmitter. Itchanges the received signal back into a message and passes the message on to its destination which may be a loudspeaker，teleprinter or computer data bank.An unfortunate characteristic of all communication channels is that noise is added to the signal. This unwanted noise may cause distorionsof sound in a telephone, or errors in a telegraph message or data.Frequency Diversion MultiplexingFrequency Diversion Multiplexing(FDM) is a one of analog technologies. A speech signal is 0~3 kHz, single sideband amplitude (SSB) modulation can be used to transfer speech signal to new frequency bands,four similar signals, for example, moved by SSB modulation to share the band from 5 to 20 kHz. The gaps between channels are known as guard spaces and these allow for errors in frequency, inadequate filtering, etc in the engineered system.Once this new baseband signal, a "group" of 4 chEmnels, has been foimed it ismoved around the Lrunk network as a single unit. A hierarchy can be set up withseveral channels fonning a "group". several groups a "supergroup" and several"supergraup" eicher a "nmsrergroup" or "hypergroup".Groups or supergroups are moved around as single units by the communicationsequipment and it is not necessary for the radios to know how many channels are involved. A radio can handle a supergroup provided sufficient bandwidth is available. The size of the groups is a compromise as treating each channel individually involves far more equipment because separate filters, modulators and oscillators are required for every channel rather than for each group. However the failure of one module will lose all of the channels associated with a group.Time Diversion MultiplexingIt is possible, with pulse modulation systems, to use the between samples to transmit signals from other circuits. The technique is knownas time diversion multiplexing (TDM). To do this, it is necessary to employ synchronized switches at eachend of the communication links to enable samples to be transmittedin turn, from each of several circuits. Thus several subscribers appear to use the link simultaneously. Although each user only has periodic short time slots, the original analog signalsbetween samples can be reconstituted at the receiver.Pulse Code ModulationIn analog modulation, the signal was used to modulate the amplitude or frequency of a carrier, directly. However, in digital modulation a stream of pulse, representing the original，is created. This stream is then used to modulate a carrier or alternatively is transmitted directly over a cable. Pulse Code Modulation (PCM) is one of the two techniques commonly used.All pulse systems depend on the analog waveform being sampled at regular intervals. The signal created by sampling our analog speech input is known as pulse amplitude modulation. It is not very useful in practice but is used as an intermediate stage towards forming a PCM signal. It will be seen later that most of the advantages of digital modulation come from the transmitted pulses having two levels only, this being known as a binary system. In PCM the height of each sample is converted into a binary number. There are three step in the process of PCM: sampling, quantizing and coding.Optical Fiber CommunicationsCommunication may be broadly defined as the transfer of information from one point to another. When the information is to be conveyed over any distance acommunication system is usually required. Within a communication system the information transfer is frequently achieved by superimposing or modulating the information on to an electromagnetic wave which acts as a carrier for the informationsignal. This modulated carrier is then transmitted to the required destination where it is received and the original information signal is obtained by demodulation. Sophisticated techniques have been developed for this process by using electromagnetic carrier wavesoperating at radio frequencies as well as microwave and millimeter wave frequencies. However，拻 communication?may also be achieved by using an electromagneticcarrier which is selected from the optical range of frequencies.In this case the information source provides an electrical signal to a transmitter comprising an electrical stage which drives an optical source to give modulation of the light-wave carrier. The optical source which provides the electrical-optical conversionmay be either a semiconductor laser or light emitting diode (LED). The transmission medium consists of an optical fiber cable and the receiver consists of an optical detector which drives a further electrical stage and hence provides demodulation optical carrier. Photodiodes (P-N, P-I-N or avalanche) and , in some instances,phototransistor and photoconductors are utilized for the detection of the optical signal and the electrical-optical conversion. Thus there is a requirement for electrical interfacing at either end of the optical link and at present the signal processing is usually performed electrically.The optical carrier may be modulated by using either an analog or digital information signal. Analog modulation involves the variation of the light emitted from the optical source in a continuous manner. With digital modulation, however, discrete changes in the light intensity are obtained (i.e. on-off pulses). Although often simpler to implement, analog modulation with an optical fiber communication system is lessefficient, requiring a far higher signal to noise ratio at the receiver than digital modulation. Also, the linearity needed for analog modulation is not always provided by semiconductor optical source, especially at high modulation frequencies. For thesereasons，analog optical fiber communications link are generally limited to shorter distances and lower bandwidths than digital links.Initially, the input digital signal from the information source is suitably encoded for optical transmission. The laser drive circuit directly modulates the intensity of the semiconductor laser with the encoded digital signal. Hence a digital optical signal is launched into the optical fiber cable. The avalanche photodiode detector (APD) is followed by a fronted-end amplifier and equalizer orfilter to provide gain as well as linear signal processing and noise bandwidth reduction. Finally, the signal obtained isdecoded to give the original digital information.Mobile CommunicationCordless Telephone SystemsCordless telephone system are full duplex communication systems that use radio to connect a portable handset to a dedicated base station，which is then connected to adedicated telephone line with a specific telephone number on the public switched telephone network (PSTN) .In first generation cordless telephone systems5(manufactured in the 1980s), the portable unit communications only to the dedicatedbase unit and only over distances of a few tens of meters.Early cordless telephones operate solely as extension telephones to a transceiver connected to a subscriber line on the PSTN and are primarily for in-home use.Second generation cordless telephones have recently been introduced which allowsubscribers to use their handsets at many outdoor locations within urban centers such as London or Hong Kong. Modern cordless telephones are sometimes combined with paging receivers so that a subscriber may first be paged and then respond to the pageusing the cordless telephone. Cordless telephone systems provide the user with limited range and mobility, as it is usually not possible to maintain a call if the user travels outside the range of the base station. Typical second generation base stations provide coverage ranges up to a few hundred meters.Cellular Telephone SystemA cellular telephone system provides a wireless connection to the PSTN for any user location within the radio range of the system.Cellular systems accommodate alarge number of users over a large geographic area, within a limited frequency spectrum. Cellular radio systems provide high quality service that is often comparable to that of the landline telephone systems. High capacity is achieved by limiting the coverage of each base station transmitter to a small geographic area called a cell so that the same radio channels may be reused by another base station located some distance away. A sophisticated switching technique called a handoff enables a call to proceeduninterrupted when the user moves from one cell to another.A basic cellular system consists of mobile station, base stations and a mobile switching center (MSC). The Mobile Switching Center is sometimes called a mobiletelephone switching office (MTSO), since it is responsible for connecting all mobiles to the PSTN in a cellular system. Each mobilecommunicates via radio with one of the base stations and may be handed-off to any number of base stations throughout the duration of a call. The mobile station contains a transceiver, an antenna, and control circuitry，and may be mounted in a vehicle or used as a portable hand-held unit. Thebase stations consists of several transmitters and receivers which simultaneously handlefull duplex communications and generally have towers which support several transmitting and receiving antennas. The base station serves as a bridge between all mobile users in the cell and connects the simultaneous mobile calls via telephone linesor microwave links to the MSC. The MSC coordinates the activities of all the base stations and connects the entire cellular system to the PSTN. A typical MSC handles 100000 cellular subscribers and 5000 simultaneous conversations at a time, andaccommodates all billing and system maintenance functions, as well. In large cities, several MSCs are used by a single carrier.Broadband CommunicationAs can be inferred from the examples of video phone and HDTV, the evolution offuture communications will be via broadband communication centered around video signals. The associated services make up a diverse set of high-speed and broadbandservices ranging from video services such as video phone，video conferencing，videosurveillance, cable television (CATV) distribution, and HDTV distribution to the high-speed data services such as high-resolution image transmission, high-speed datatransmission, and color facsimile. The means of standardizing these various broadbandcommunication services so that they can be provided in an integrated manner is no other than the broadband integrated services digital network (B-ISDN). Simple put, therefore,the future communications network can be said to be a broadband telecommunicationsystem based on the B-ISDN.For realization of the B-ISDN, the role of several broadband communicationtechnologies is crucial. Fortunately, the remarkable advances in the field of electronics and fiber optics have led to the maturation of broadband communication technologies.As the B-ISDN becomes possible on the optical communication foundation, the relevant manufacturing technologies for light-source and passive devices and for optical fiberhave advanced to considerable levels. Advances in high-speed device and integratedcircuit technologies for broadband signal processing are also worthy of close attention. There has also been notable progress in software, signal processing, and video equipment technologies. Hence, from the technological standpoint, the B-ISDN hasfinally reached a realizable state.On the other, standardization activities associated with broadband communication have been progressing. The Synchronous Optical Network (SONET) standardization centered around the T1 committee eventually bore fmit in the form of the Synchronous Digital Hierarchy (SDH) standards of the International Consultative Committee in Telegraphy and Telephony (CCITT), paving the way for synchronous digital transmission based on optical communication. The standardization activities of the 5integrated services digital network (ISDN), which commenced in early 1980s with the objective of integrating narrowband services, expanded in scope with the inclusion of broadband services, leading to the standardization of the B-ISDN in late1980抯 and establishing the concept of asynchronous transfer mode (ATM)communication in process. In addition, standardization of various video signals is becoming finalized through the cooperation among such organizations as CCITT, the International Radio-communications Consultative Committee (CCIR), and theInternational Standards Organization (ISO), and reference protocols for high-speedpacket communication are being standardized through ISO, CCITT, and the Institute of Electrical and Electronics Engineer (IEEE).Various factors such as these have made broadband communication realizable.5Therefore, the 1990s is the decade in which matured broadband communicationtechnologies will be used in conjunction with broadband standards to realize broadband communication networks. In the broadband communication network, the fiber opticnetwork will represent the physical medium for implementing broadband communication, while synchronous transmission will make possible the transmission of broadband service signals over the optical medium. Also, the B-ISDN will be essentialas the broadband telecommunication network established on the basis of optical medium and synchronous transmission and ATM is the communication means that enables the realization of the B-ISDN. The most important of the broadband services to be providedthrough the B-ISDN are high-speed data communication services and videocommunication services.Image AcquisitionA TV camera is usually used to take instantaneous images and transform them into electrical signals, which will be further translated into binary numbers for the computer to handle. The TV camera scans oneline at a time. Each line is further divided into hundreds of pixels. The whole frame is divided into hundreds (for example, 625) of lines.The brightness of a pixel can be represented by a binary number with certain bits, for example, 8 bits. The value of the binary number varies from 0 to 255, a range great enough to accommodate all possible contrast levels of images taken from real scene.These binary numbers are sorted in an RAM (it must have a great capacity) ready for processing by the computer.Image ProcessingImage processing is for improving the quality of the images obtained. First, it is necessary to improve the signal-to-noise ratio. Here noise refers to any interference flaw or aberation that obscure the objects on the image. Second, it is possible to improve contrast, enhance sharpness of edges between images through various computational means.Image AnalysisIt is for outlining all possible objects that are included in the scene. A computer program checks through the binary visual informationin store for it and identifies specific feature and characteristics of those objects. Edges or boundaries are identifiablebecause of the different brightness levels on either side of them. Usingcertain algorithms, the computer program can outline all possible boundaries of the objects in the scene. Image analysis also looks for textures and shadings between lines.Image ComprehensionImage Comprehension means understanding what is in a scene. Matching the prestored binary visual information with certain templates which represent specific objects in a binary form is technique borrowed from artificial intelligence, commonly referred to as "templeite matching"emplate matching? One by one,the templates are checked against the binary information representing the scene. Once a match occurs, an object is identified. The template matching process continues until all possible objects in the scene have been identified, otherwise it fails.通信系统一般的通信系统由下列部分组成:信源。
无线电力传输系统
实现方法
3.辐射式：利用微波辐射传输能量
1979年，美国航空航天局NASA和美国能源部联合提出太阳 能计划，建立“SPS太阳能卫星基准系统”。 SPS（Solar Power satellite）是太阳能发电卫星，处在地球约36000km 的静止轨道上，那里太阳的能量约为地球上的1.4倍。据测算， 一个SPS所装载的太阳电池的直流输出功率为10GW，其输 出的电力通过振荡器变换成微波电力，从送电的天线向地球 表面以微波（2.45GHz）形式无线送电。地球上的接收天线 由半波长的偶极天线、整流二极管、低通滤波器及旁路电容 组成，可接收到5GW的电力。
无线电力传输系统
—WIRELESS POWER TRANSMISSION
综述
Wireless power or wireless energy transmission is the transmission of electrical energy from a power source to an electrical load without man-made conductors. —
实现方法
优点：传输距离非常远，可定向传输能量，也可全方 向传输。
缺点：传输效率低，安全性有待验证。
前景展望
谢谢！
沃登克里弗塔
综述
20世纪60年代初期雷声公司(Raytheon)的布朗(W. C. Brown)做了大量的无线电能 传输研究工作,从而奠定了无线电能传输的实验基础,使这一概念变成了现实。 2007年，美国麻省理工学院的Marin Soljacic等人在无线电能传输方面取得了新 进 展，他们用两米外的一个电源，“隔空”点亮了一盏60瓦的灯泡。 2008年12月17日成立无线充电联盟（Wireless Power Consortium），2010年8月 31日，无线充电联盟在北京正式将无线充电技术引入中国。
读英语文章 远程电力传输
February 25,2021(CNN)A solar panel in space is collecting energy that could one day be beamed to anywhere on Earth太空中的一块太阳能电池板正在收集能量，这些能量有一天可能会被发射到地球上的任何地方Scientists working in the US have successfully tested a solar panel the size of a pizza box in space, designed as a prototype for a future system to send electricity from space back to any point on Earth.美国的科学家们成功地在太空中测试了一块披萨盒大小的太阳能电池板，该电池板被设计为未来系统的原型，可以将太空中的电力发送回地球上的任何地方。
The panel -- known as a Photovoltaic Radiofrequency Antenna Module (PRAM) -- was first launched in May 2020, attached to the Pentagon's X-37B unmanned drone, to harness light from the sun to convert to electricity. The drone is looping Earth every 90 minutes.该电池板被称为光伏射频天线模块(PRAM)，于2020年5月首次发射，连接在五角大楼的X-37B无人机上，利用来自太阳的光转化为电能。
无人机每90分钟在地球上空盘旋一次。
The panel is designed to make best use of the light in space, which doesn't pass through the atmosphere, and so retains the energy of blue waves, making it more powerful than the sunlight that reaches Earth. Blue light diffuses on entry into the atmosphere, which is why the sky appears blue.这种电池板的设计是为了充分利用太空中的光线，因为太空光线不会穿过大气层，所以它保留了蓝波的能量，使其比到达地球的阳光更有能量。
5G无线通信网络中英文对照外文翻译文献
5G无线通信网络中英文对照外文翻译文献(文档含英文原文和中文翻译)翻译：5G无线通信网络的蜂窝结构和关键技术摘要第四代无线通信系统已经或者即将在许多国家部署。
然而，随着无线移动设备和服务的激增，仍然有一些挑战尤其是4G所不能容纳的，例如像频谱危机和高能量消耗。
无线系统设计师们面临着满足新型无线应用对高数据速率和机动性要求的持续性增长的需求，因此他们已经开始研究被期望于2020年后就能部署的第五代无线系统。
在这篇文章里面，我们提出一个有内门和外门情景之分的潜在的蜂窝结构，并且讨论了多种可行性关于5G无线通信系统的技术，比如大量的MIMO技术，节能通信，认知的广播网络和可见光通信。
面临潜在技术的未知挑战也被讨论了。
介绍信息通信技术（ICT）创新合理的使用对世界经济的提高变得越来越重要。
无线通信网络在全球ICT战略中也许是最挑剔的元素，并且支撑着很多其他的行业，它是世界上成长最快最有活力的行业之一。
欧洲移动天文台（EMO）报道2010年移动通信业总计税收1740亿欧元,从而超过了航空航天业和制药业。
无线技术的发展大大提高了人们在商业运作和社交功能方面通信和生活的能力无线移动通信的显著成就表现在技术创新的快速步伐。
从1991年二代移动通信系统(2G)的初次登场到2001年三代系统（3G）的首次起飞，无线移动网络已经实现了从一个纯粹的技术系统到一个能承载大量多媒体内容网络的转变。
4G无线系统被设计出来用来满足IMT-A技术使用IP面向所有服务的需求。
在4G系统中，先进的无线接口被用于正交频分复用技术（OFDM），多输入多输出系统（MIMO）和链路自适应技术。
4G无线网络可支持数据速率可达1Gb/s的低流度，比如流动局域无线访问，还有速率高达100M/s的高流速，例如像移动访问。
LTE系统和它的延伸系统LTE-A，作为实用的4G系统已经在全球于最近期或不久的将来部署。
然而，每年仍然有戏剧性增长数量的用户支持移动宽频带系统。
无线通信外文文献译文
无线通信电机及电子学工程师联合会2005年国际研讨会上关于微波，天线，传播和无线通信的电磁兼容技术在技术发展上的最新动态竹内清一地区10主任东京电机大学摘要本文介绍无线通信技术的最新发展趋势以及组成无线通信技术的四个部分。
第一个也是最重要的发展是全球互联网流量的增长。
在全球互联网流量增长的重要趋势总结在全球地理区域和他们的互联网渗透方面。
第二个部分是实现无线通信所必备的骨干网络中的硬件配套技术的发展。
第三部分是无线通信的中心问题，特别是本地个人用户，第四和最后一个部分是总结发言。
1简介许多技术的发展显然是需要通过无线通信的实现，以满足环保要求的社会背景需要这的种技术发展。
例如，互联网流量每年约增加一倍，而这种快速增长的互联网流量和WWW（全球资讯网）需要为骨干网络配置无线并不一定需要，但对本地无线通信的实现至关重要的巨大带宽。
骨干网主要靠光纤电缆的技术发展以及相关的配套技术配套支持运行的。
这样的等配套技术包括信息处理和WDM（波分复用）和他们使取得的高效无线通信成为了可能。
无线通信，特别是无线互联网特别是无线互联网对于集中，甚至不断移动的短距离范围内的本地个人用户非常重要。
在IEEE 802.11是无线局域网用于与合作媒介访问控制协议的一般原则，也可以扩展到其他类型的无线网络，如无线个人区域网络（WPAN的）。
该服务区的范围变得越来越小，以便让当地个人用户的充分利用无线通讯媒介用于无线互联网流量。
无线通信是无线互联网最便捷的传输介质，这种无线传输介质的有效使用是至关重要的。
可靠的访问几十兆赫可以跨相当大的在其中无线互联网将需要十倍多的细胞的语音系统的地理区域，每个这样的monocles将测量面积小，几十平方米的大约是百分之常规细胞的大小。
它比传统电池可以容纳更多给定的数据速率的有源器件。
为了使这成为可能的，有效的射频频谱空间复用是必要的，从而能够让个人用户访问更贴近低功率的传输点。
对于快速增长的互联网流量的整体通信系统可以由的三个关键的重要领域的技术发展来支持，1）硬件技术需要个人用户的高密度无线传输的实现，2）配套硬件技术的光纤电缆，3）整体通信系统的运作和维护方面的软件技术，我们主要回顾了前两部分的硬件方面2互联网的发展表1显示了最高的互联网普及率最高的24个国家。
1外文文献翻译原文及译文汇总
华北电力大学科技学院毕业设计（论文）附件外文文献翻译学号：121912020115姓名：彭钰钊所在系别：动力工程系专业班级：测控技术与仪器12K1指导教师：李冰原文标题：Infrared Remote Control System Abstract2016 年 4 月 19 日红外遥控系统摘要红外数据通信技术是目前在世界范围内被广泛使用的一种无线连接技术，被众多的硬件和软件平台所支持。
红外收发器产品具有成本低，小型化，传输速率快，点对点安全传输，不受电磁干扰等特点，可以实现信息在不同产品之间快速、方便、安全地交换与传送，在短距离无线传输方面拥有十分明显的优势。
红外遥控收发系统的设计在具有很高的实用价值，目前红外收发器产品在可携式产品中的应用潜力很大。
全世界约有1亿5千万台设备采用红外技术，在电子产品和工业设备、医疗设备等领域广泛使用。
绝大多数笔记本电脑和手机都配置红外收发器接口。
随着红外数据传输技术更加成熟、成本下降，红外收发器在短距离通讯领域必将得到更广泛的应用。
本系统的设计目的是用红外线作为传输媒质来传输用户的操作信息并由接收电路解调出原始信号，主要用到编码芯片和解码芯片对信号进行调制与解调，其中编码芯片用的是台湾生产的PT2262，解码芯片是PT2272。
主要工作原理是：利用编码键盘可以为PT2262提供的输入信息，PT2262对输入的信息进行编码并加载到38KHZ的载波上并调制红外发射二极管并辐射到空间，然后再由接收系统接收到发射的信号并解调出原始信息，由PT2272对原信号进行解码以驱动相应的电路完成用户的操作要求。
关键字：红外线；编码；解码；LM386；红外收发器。
1 绪论1．1 课题研究的背景及意义红外数据通信技术是目前在世界范围内被广泛使用的一种无线连接技术，被众多的硬件和软件平台所支持。
是一种通过数据电脉冲和红外光脉冲之间的相互转换实现无线的数据收发的技术。
红外收发器产品具有成本低，小型化，传输速率快，点对点安全传输，不受电磁干扰等特点，可以实现信息在不同产品之间快速、方便、安全地交换与传送，在短距离无线传输方面拥有十分明显的优势。
电子通信专业 外文翻译 外文文献 英文文献 电信现代运营
毕业设计（外文翻译材料）Telecommunication Modern Operation TelephoneIn an analogue telephone network, the caller is connected to the person he wants to talk to by switches at various telephone exchanges. The switches form an electrical connection between the two users and the setting of these switches is determined electronically when the caller dials the number. Once the connection is made, the caller's voice is transformed to an electrical signal using a small microphone in the caller's handset. This electrical signal is then sent through the network to the user at the other end where it transformed back into sound by a small speaker in that person's handset. There is a separate electrical connection that works in reverse, allowing the users to converse.The fixed-line telephones in most residential homes are analogue — that is, the speaker's voice directly determines the signal's voltage. Although short-distance calls may be handled from end-to-end as analogue signals, increasingly telephone service providers are transparently converting the signals to digital for transmission before converting them back to analogue for reception. The advantage of this is that digitized voice data can travel side-by-side with data from the Internet and can be perfectly reproduced in long distance communication (as opposed to analogue signals that are inevitably impacted by noise).- 1 --Mobile phones have had a significant impact on telephone networks. Mobile phone subscriptions now outnumber fixed-line subscriptions in many markets. Sales of mobile phones in 2005 totalled 816.6 million with that figure being almost equally shared amongst the markets of Asia/Pacific (204 m), Western Europe (164 m), CEMEA (Central Europe, the Middle East and Africa) (153.5 m), North America (148 m) and Latin America (102 m). In terms of new subscriptions over the five years from 1999, Africa has outpaced other markets with 58.2% growth. Increasingly these phones are being serviced by systems where the voice content is transmitted digitally such as GSM or W-CDMA with many markets choosing to depreciate analogue systems such as AMPS.There have also been dramatic changes in telephone communication behind the scenes. Starting with the operation of TAT-8 in 1988, the 1990s saw the widespread adoption of systems based on optic fibres. The benefit of communicating with optic fibres is that they offer a drastic increase in data capacity. TAT-8 itself was able to carry 10 times as many telephone calls as the last copper cable laid at that time and today's optic fibre cables are able to carry 25 times as many telephone calls as TAT-8. This increase in data capacity is due to several factors: First, optic fibres are physically much smaller than competing technologies. Second, they do not suffer from crosstalk which means several hundred of them can be easily bundled together in a single cable. Lastly, improvements in multiplexing have led to an exponential growth in the data capacity of a single fibre.Assisting communication across many modern optic fibre networks is a protocol known as Asynchronous Transfer Mode (ATM). The ATM protocol allows for the side-by-side data transmission mentioned in the second paragraph. It is suitable for public telephone networks because it establishes a pathway for data through the network and associates a traffic contract with that pathway. The traffic contract is essentially an agreement between the client and the network about how the network is to handle the data; if the network cannot meet the conditions of the traffic contract it does not accept the connection. This is important because telephone calls can- 2 --negotiate a contract so as to guarantee themselves a constant bit rate, something that will ensure a caller's voice is not delayed in parts or cut-off completely. There are competitors to ATM, such as Multiprotocol Label Switching (MPLS), that perform a similar task and are expected to supplant ATM in the future.Radio and televisionIn a broadcast system, a central high-powered broadcast tower transmits a high-frequency electromagnetic wave to numerous low-powered receivers. The high-frequency wave sent by the tower is modulated with a signal containing visual or audio information. The antenna of the receiver is then tuned so as to pick up the high-frequency wave and a demodulator is used to retrieve the signal containing the visual or audio information. The broadcast signal can be either analogue (signal is varied continuously with respect to the information) or digital (information is encoded as a set of discrete values).The broadcast media industry is at a critical turning point in its development, with many countries moving from analogue to digital broadcasts. This move is made possible by the production of cheaper, faster and more capable integrated circuits. The chief advantage of digital broadcasts is that they prevent a number of complaints with traditional analogue broadcasts. For television, this includes the elimination of problems such as snowy pictures, ghosting and other distortion. These occur because of the nature of analogue transmission, which means that perturbations due to noise will be evident in the final output. Digital transmission overcomes this problem because digital signals are reduced to discrete values upon reception and hence small perturbations do not affect the final output. In a simplified example, if a binary message 1011 was transmitted with signal amplitudes [1.0 0.0 1.0 1.0] and received with signal amplitudes [0.9 0.2 1.1 0.9] it would still decode to the binary message 1011 — a perfect reproduction of what was sent. From this example, a problem with digital transmissions can also be seen in that if the noise is great enough it can significantly alter the decoded message. Using forward error correction a receiver can- 3 --correct a handful of bit errors in the resulting message but too much noise will lead to incomprehensible output and hence a breakdown of the transmission.In digital television broadcasting, there are three competing standards that are likely to be adopted worldwide. These are the ATSC, DVB and ISDB standards; the adoption of these standards thus far is presented in the captioned map. All three standards use MPEG-2 for video compression. ATSC uses Dolby Digital AC-3 for audio compression, ISDB uses Advanced Audio Coding (MPEG-2 Part 7) and DVB has no standard for audio compression but typically uses MPEG-1 Part 3 Layer 2. The choice of modulation also varies between the schemes. In digital audio broadcasting, standards are much more unified with practically all countries choosing to adopt the Digital Audio Broadcasting standard (also known as the Eureka 147 standard). The exception being the United States which has chosen to adopt HD Radio. HD Radio, unlike Eureka 147, is based upon a transmission method known as in-band on-channel transmission that allows digital information to "piggyback" on normal AM or FM analogue transmissions.However, despite the pending switch to digital, analogue receivers still remain widespread. Analogue television is still transmitted in practically all countries. The United States had hoped to end analogue broadcasts on December 31, 2006; however, this was recently pushed back to February 17, 2009. For analogue television, there are three standards in use. These are known as PAL, NTSC and SECAM. For analogue radio, the switch to digital is made more difficult by the fact that analogue receivers are a fraction of the cost of digital receivers. The choice of modulation for analogue radio is typically between amplitude modulation (AM) or frequency modulation (FM). To achieve stereo playback, an amplitude modulated subcarrier is used for stereo FM.The InternetThe Internet is a worldwide network of computers and computer networks that can communicate with each other using the Internet Protocol. Any computer on the Internet has a unique IP address that can be used by other computers to route- 4 --information to it. Hence, any computer on the Internet can send a message to any other computer using its IP address. These messages carry with them the originating computer's IP address allowing for two-way communication. In this way, the Internet can be seen as an exchange of messages between computers.An estimated 16.9% of the world population has access to the Internet with the highest access rates (measured as a percentage of the population) in North America (69.7%), Oceania/Australia (53.5%) and Europe (38.9%).In terms of broadband access, Iceland (26.7%), South Korea (25.4%) and the Netherlands (25.3%) lead the world.The Internet works in part because of protocols that govern how the computers and routers communicate with each other. The nature of computer network communication lends itself to a layered approach where individual protocols in the protocol stack run more-or-less independently of other protocols. This allows lower-level protocols to be customized for the network situation while not changing the way higher-level protocols operate. A practical example of why this is important is because it allows an Internet browser to run the same code regardless of whether the computer it is running on is connected to the Internet through an Ethernet or Wi-Fi connection. Protocols are often talked about in terms of their place in the OSI reference model, which emerged in 1983 as the first step in an unsuccessful attempt to build a universally adopted networking protocol suite.For the Internet, the physical medium and data link protocol can vary several times as packets traverse the globe. This is because the Internet places no constraints on what physical medium or data link protocol is used. This leads to the adoption of media and protocols that best suit the local network situation. In practice, most intercontinental communication will use the Asynchronous Transfer Mode (ATM) protocol (or a modern equivalent) on top of optic fibre. This is because for most intercontinental communication the Internet shares the same infrastructure as the public switched telephone network.- 5 --At the network layer, things become standardized with the Internet Protocol (IP) being adopted for logi cal addressing. For the world wide web, these “IP addresses” are derived from the human readable form using the Domain Name System (e.g.72.14.207.99 is derived from ). At the moment, the most widely used version of the Internet Protocol is version four but a move to version six is imminent.At the transport layer, most communication adopts either the Transmission Control Protocol (TCP) or the User Datagram Protocol (UDP). TCP is used when it is essential every message sent is received by the other computer where as UDP is used when it is merely desirable. With TCP, packets are retransmitted if they are lost and placed in order before they are presented to higher layers. With UDP, packets are not ordered or retransmitted if lost. Both TCP and UDP packets carry port numbers with them to specify what application or process the packet should be handled by. Because certain application-level protocols use certain ports, network administrators can restrict Internet access by blocking the traffic destined for a particular port.Above the transport layer, there are certain protocols that are sometimes used and loosely fit in the session and presentation layers, most notably the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols. These protocols ensure that the data transferred between two parties remains completely confidential and one or the other is in use when a padlock appears at the bottom of your web browser. Finally, at the application layer, are many of the protocols Internet users would be familiar with such as HTTP (web browsing), POP3 (e-mail), FTP (file transfer), IRC (Internet chat), BitTorrent (file sharing) and OSCAR (instant messaging).Local area networksDespite the growth of the Internet, the characteristics of local area networks (computer networks that run at most a few kilometres) remain distinct. This is because networks on this scale do not require all the features associated with larger networks and are often more cost-effective and efficient without them.- 6 --In the mid-1980s, several protocol suites emerged to fill the gap between the data link and applications layer of the OSI reference model. These were Appletalk, IPX and NetBIOS with the dominant protocol suite during the early 1990s being IPX due to its popularity with MS-DOS users. TCP/IP existed at this point but was typically only used by large government and research facilities. As the Internet grew in popularity and a larger percentage of traffic became Internet-related, local area networks gradually moved towards TCP/IP and today networks mostly dedicated to TCP/IP traffic are common. The move to TCP/IP was helped by technologies such as DHCP that allowed TCP/IP clients to discover their own network address —a functionality that came standard with the AppleTalk/IPX/NetBIOS protocol suites.It is at the data link layer though that most modern local area networks diverge from the Internet. Whereas Asynchronous Transfer Mode (ATM) or Multiprotocol Label Switching (MPLS) are typical data link protocols for larger networks, Ethernet and Token Ring are typical data link protocols for local area networks. These protocols differ from the former protocols in that they are simpler (e.g. they omit features such as Quality of Service guarantees) and offer collision prevention. Both of these differences allow for more economic set-ups.Despite the modest popularity of Token Ring in the 80's and 90's, virtually all local area networks now use wired or wireless Ethernet. At the physical layer, most wired Ethernet implementations use copper twisted-pair cables (including the common 10BASE-T networks). However, some early implementations used coaxial cables and some recent implementations (especially high-speed ones) use optic fibres. Optic fibres are also likely to feature prominently in the forthcoming 10-gigabit Ethernet implementations. Where optic fibre is used, the distinction must be made between multi-mode fibre and single-mode fibre. Multi-mode fibre can be thought of as thicker optical fibre that is cheaper to manufacture but that suffers from less usable bandwidth and greater attenuation (i.e. poor long-distance performance).- 7 --电信现代运营电话在一个模拟电话网络, 来电者通过交换机与对方进行不同的电话交流｡开关在两用户间形成一个电气连接,其参数是由来电者按键时的电气特性决定的｡一旦连接,来电者的声音通过来电端处的电话听筒转化为电信号｡然后电信号通过网络发送到另一端的用户,并通过小型扬声器将信号转化为声音｡有一个单独的电气连接用于进行转换,以使用户交谈｡固定电话,在多数居民区是模拟电话,那就是,发言者的声音,直接决定着信号的电压｡虽然距离短,来电可能会被作为模拟信号的端到端信号处理,越来越多电话服务供应商是适度的在传输前将模拟信号数字化以便传输,之后转为模拟信号以便接收｡它的优势是,数字化语音数据可以从互联网上以数字形式传输,而且可以完全转载于远程通信｡(对比来看,模拟信号无可避免会受到噪声影响｡) 手机已对电话网络产生了重大影响｡移动电话用户现在在许多市场超过了固定线路用户｡手机销量在2005年总额为8.166亿,被一下数字平分,其中亚洲/太平洋(2.04亿),西欧(1.64亿),cemea(中欧,中东和非洲)(1.535亿),北美(1.48亿)和拉丁美洲(1.02亿)｡在从1999年之后的五年时间内新增用户来看,非洲已以58.2 %的增长超过了其他地区的市场｡手机逐渐采用如GSM或W-CDMA这些可以数字化传输语音信号的系统,从而使AMPS这样的模拟系统衰落｡电话通信也隐约地有了戏剧性的变化｡开始运作的TAT-8(跨大西洋传输电缆)始于1988年, 20世纪90年代见证了基于光纤系统的普及｡光纤传输的优势在于其所提供的数据容量的急剧增加｡TAT-8可以传输相当于同轴电缆电话10倍的数据,而现在的光纤能传输25倍于TAT-8的数据｡数据能力的增加是由于几个因素:第一,光纤体积远小于其他竞争技术｡第二,他们不受到串扰这意味着数百条光纤可以很容易地捆绑在一个单一的电缆内｡最后,复用技术的改善导致了单条光纤数据容量的指数增长｡基于现代光纤网络的通信是一项称为异步传输模式( ATM )的协议｡如第二段所说,ATM协议允许为并排的数据传输｡它适用于公共电话网络,因为它建立了通过网络数据通道并以此进行通信｡传输协议基本上是一个用户与网络之间的协议,它规定了网络如何来处理数据;如果网络不能满足条件的传输协议,它不接受连接｡这很重要,因为电话可以通过协议,保证自己的恒定比特率,这将确保来电者的声音,不是延迟的部分或完全切断｡ATM的竞争对手,如多标签交换(MPLS),执行类似的任务,并可望在未来取代ATM｡电台和电视台在一个广播系统,中央高功率广播塔传输高频率的电磁波,到众多的低功率接收器上｡由广播塔发送的高频率波由信号调制且该信号载有视频或音频信息｡接收天线稍作调整，以提取高频率波,解调器用来恢复载有视力或音频信息的信号｡广播信号可以是模拟(信号多种多样,载有信息且连续)或数字(信息作为一套离散值,可以编码)｡广播媒体业正处于发展中一个关键的转折点,许多国家都从模拟发展到数字广播｡此举是可使生产更经济,更快且更能够集成电路｡与传统的模拟广播相比,数字广播最大的优势是,他们防止了一些投诉｡对电视来说,这包括消除问题,如雪花屏,重影和其他失真｡这些发生原因,是因为模拟传输的性质,这意味着噪声干扰会明显影响最后的输出｡数字传输,克服了这个问题,因为接收时数字信号变为离散值,这样小扰动不影响最终输出｡举一个简单的例子,一个二进制信息1011,已与信号的振幅[ 1.0 0.0 1.0 1.0 ]调制,并收到信号的振幅[ 0.9 0.2 1.1 0.9 ]它将仍然解码为二进制信息1011-一个完美原码再现｡从这个例子可以看出,数字传输也由一个问题,如果噪音足够大,它可以大大改变解码信息｡使用前向错误校正接收器可以在最终结果中纠正少数比特错误,但太多的噪音将导致难以理解的输出,因此,传输失败｡在数字电视广播中,有3个相互竞争的标准,很可能是全世界公认的｡它们是ATSC标准,DVB标准和ISDB标准;通过这些标准,到目前为止,应用于标题地图｡所有这三个标准,使用MPEG - 2 视频压缩｡ATSC标准采用杜比数字AC - 3音频压缩,ISDB利用先进音频编码( MPEG - 2的第7部分),而DVB没有音频压缩标准,但通常使用MPEG - 1第3部分第2层｡不同标准所用的调制方式也有所不同｡在数字音频广播中,标准更为统一,几乎所有国家都选择采用数字音频广播的标准(也称为作为尤里卡147标准)｡也有例外,美国已选择采用高清广播｡高清广播,不同于尤里卡147 ,它是基于称为在带内通道传输的传输方法,这使数字化信息,进行“背驮式”AM或FM模拟传输｡然而,尽管数字化迫在眉睫,模拟接收机仍然普遍应用｡模拟电视仍然传送几乎所有国家｡美国希望于2006年12月31日之前结束模拟广播;不过,最近又推到2009年2月17日｡对于模拟电视,有三个标准在使用中｡它们是PAL制式,NTSC制式和SECAM制式｡模拟电台,切换到数字变得更加困难,因为模拟接收器只占数字接收机的一小部分成本｡模拟电台调制方式通常采用AM(幅度调制)或FM(频率调制)｡为实现立体声播放,振幅调制副载波用于立体声调频｡互联网互联网是一个全球计算机组成的网络,也是一种用IP联系在一起的计算机网络｡在互联网上的任何一台计算机都有一个唯一的IP地址,其他计算机可以用其进行路由选择｡因此,在互联网上,任何一台电脑可以通过IP地址传送讯息给任何其他的计算机｡这些带有计算机IP地址的信息,允许计算机之间双向沟通｡这样一来,互联网可以被看作是一个计算机之间信息的交换｡据估计,16.9 %的世界人口已经进入互联网且具有最高访问率(以人口百分比衡量),它们在北美地区(69.7 %),大洋洲/澳大利亚(53.5%)和欧洲(38.9%)｡在宽带接入方面,冰岛(26.7%),韩国(25.4%)和荷兰(25.3 %)世界领先｡互联网的成功,部分是因为协议管理计算机和路由器如何互相沟通｡计算机网络通信本身的性质,有助于分层实现,此时,协议栈中的各个独立协议或多或少独立于其他协议｡这使得低级别的协议适应网络的情况,而不影响高层协议的实现｡一个实际的例子可以说明它的重要性,因为它允许一个互联网浏览器上运行相同的代码，不管运行的计算机连接到互联网是通过以太网还是通过Wi - Fi连接｡协议经常以其在OSI参考模型中的位置命名,1983年为第一步,也是一次不成功的尝试,它试图建立一个普遍采用的网络协议套件｡对于互联网来说,物理介质和数据链路层协议可以不同的数倍包遍历全球｡这是因为互联网对所用的物理介质或数据链路协议没有限制｡这导致媒体和协议的应用,它们最适合本地网络的情况｡在实践中,多数洲际通讯将使用异步转移模式( ATM )协议(或一个现代的替代物)并辅以光纤｡这是因为,对于大多数的洲际通信来说,互联网与公共交换式电话网络一样拥有相同的基础设施｡在网络层,适用于逻辑寻址的IP开始标准化｡在万维网上,这些“IP地址”来自通过域名系统处理的人类可读格式(例如72.14.207.99是来自)中｡目前,使用最广泛的版本的互联网协议是版本 4 ,但向版本六过渡已是迫在眉睫｡在传输层大部分通信采用的是传输控制协议(TCP)或用户数据报协议(UDP)｡TCP是基本协议,每条来自其他计算机的消息均需采用TCP,而UDP只有在有利时才会被采用｡有了TCP,数据包若在它们置于更高层次前丢失或乱序,它们会被重发｡有了UDP,数据包丢失时会乱序,也不会重发｡TCP和UDP数据包携带端口以便指出数据包应交由哪些应用程序或进程｡因为某些应用级协议使用某些端口,网络管理员可以通过阻断某一特定端口为目的端口的传输限制上网｡在传输层之上,有一些协议会用到并适当应用于会话层和表示层,最显着的是安全套接层(SSL)和传输层安全(TLS)协议｡这些协议,确保双方之间传输的数据仍然完全保密并且一方或另一方在使用时,挂锁出现于Web浏览器的底部｡最后,在应用层,有很多的协议为互联网用户所熟悉,如HTTP ( Web浏览) , 的POP3 (电子邮件),FTP (档案传输),IRC (网上聊天),BitTorrent(文件共享)和OSCAR(即时通讯)｡局域网不看互联网的发展, 仅局域网的特点(运行于几公里内的计算机网络)仍然明显｡这是因为这种规模的网络并不需要所有与较大的网络有关的功能,因此往往更具成本效益和高效率｡在二十世纪八十年代中期,几个协议套件的出现,填补了OSI参考模型中数据链路层和应用层之间的空隙｡如AppleTalk,IPX和NetBios与20世纪90年代初占主导地位,因MS-DOS而广受欢迎的协议套件IPX｡而TCP / IP,在这一点上,通常只用于大型政府和研究设施｡随着互联网的受欢迎程度的增长以及较大的流量与互联网逐渐相关,局域网逐步走向TCP / IP｡今天的网络大多用于TCP / IP流量是常见的｡向TCP / IP的转变由如允许的TCP / IP客户发现自己的网络地址的DHCP的技术支撑,而这与A ppleTalk,IPX/和N etBIOS协议套件以其成为标准｡在数据链路层,最现代的局域网偏离互联网｡而异步转移模式(ATM)或多协议标签转换(MPLS)技术是典型的数据链路协议,适用于较大的网络｡以太网和令牌环网是典型的局域网数据链路协议｡这些协议不同于前协议,因为它们更简单(例如,它们省略了服务质量保证等功能) ,并提供碰撞预防｡双方的这些差异,是基于经济成本的考虑｡尽管令牌环在80年代和90年代有了一定的普及,但是现在几乎所有的局域网使用有线或无线以太网｡在物理层,大多数有线以太网实现使用铜双绞线电缆(包括常用的10 Base-T的网络)｡然而,一些早期的实现使用同轴电缆,而最近的一些实现(特别是超高速的)使用光纤｡光纤也可能在即将到来的10千兆以太网的实现中有着出色的表现｡用光纤时,必须对多模光纤和单模光纤加以区分｡对于制造商来说,多模光纤可以被认为是便宜的厚光纤,但只有较少可用的带宽和更大的衰减(即较差的长途性能)｡。
电子通信专业 外文翻译 外文文献 英文文献 电信现代运营
毕业设计（外文翻译材料）Telecommunication Modern Operation TelephoneIn an analogue telephone network, the caller is connected to the person he wants to talk to by switches at various telephone exchanges. The switches form an electrical connection between the two users and the setting of these switches is determined electronically when the caller dials the number. Once the connection is made, the caller's voice is transformed to an electrical signal using a small microphone in the caller's handset. This electrical signal is then sent through the network to the user at the other end where it transformed back into sound by a small speaker in that person's handset. There is a separate electrical connection that works in reverse, allowing the users to converse.The fixed-line telephones in most residential homes are analogue — that is, the speaker's voice directly determines the signal's voltage. Although short-distance calls may be handled from end-to-end as analogue signals, increasingly telephone service providers are transparently converting the signals to digital for transmission before converting them back to analogue for reception. The advantage of this is that digitized voice data can travel side-by-side with data from the Internet and can be perfectly reproduced in long distance communication (as opposed to analogue signals that are inevitably impacted by noise).- 1 --Mobile phones have had a significant impact on telephone networks. Mobile phone subscriptions now outnumber fixed-line subscriptions in many markets. Sales of mobile phones in 2005 totalled 816.6 million with that figure being almost equally shared amongst the markets of Asia/Pacific (204 m), Western Europe (164 m), CEMEA (Central Europe, the Middle East and Africa) (153.5 m), North America (148 m) and Latin America (102 m). In terms of new subscriptions over the five years from 1999, Africa has outpaced other markets with 58.2% growth. Increasingly these phones are being serviced by systems where the voice content is transmitted digitally such as GSM or W-CDMA with many markets choosing to depreciate analogue systems such as AMPS.There have also been dramatic changes in telephone communication behind the scenes. Starting with the operation of TAT-8 in 1988, the 1990s saw the widespread adoption of systems based on optic fibres. The benefit of communicating with optic fibres is that they offer a drastic increase in data capacity. TAT-8 itself was able to carry 10 times as many telephone calls as the last copper cable laid at that time and today's optic fibre cables are able to carry 25 times as many telephone calls as TAT-8. This increase in data capacity is due to several factors: First, optic fibres are physically much smaller than competing technologies. Second, they do not suffer from crosstalk which means several hundred of them can be easily bundled together in a single cable. Lastly, improvements in multiplexing have led to an exponential growth in the data capacity of a single fibre.Assisting communication across many modern optic fibre networks is a protocol known as Asynchronous Transfer Mode (ATM). The ATM protocol allows for the side-by-side data transmission mentioned in the second paragraph. It is suitable for public telephone networks because it establishes a pathway for data through the network and associates a traffic contract with that pathway. The traffic contract is essentially an agreement between the client and the network about how the network is to handle the data; if the network cannot meet the conditions of the traffic contract it does not accept the connection. This is important because telephone calls can- 2 --negotiate a contract so as to guarantee themselves a constant bit rate, something that will ensure a caller's voice is not delayed in parts or cut-off completely. There are competitors to ATM, such as Multiprotocol Label Switching (MPLS), that perform a similar task and are expected to supplant ATM in the future.Radio and televisionIn a broadcast system, a central high-powered broadcast tower transmits a high-frequency electromagnetic wave to numerous low-powered receivers. The high-frequency wave sent by the tower is modulated with a signal containing visual or audio information. The antenna of the receiver is then tuned so as to pick up the high-frequency wave and a demodulator is used to retrieve the signal containing the visual or audio information. The broadcast signal can be either analogue (signal is varied continuously with respect to the information) or digital (information is encoded as a set of discrete values).The broadcast media industry is at a critical turning point in its development, with many countries moving from analogue to digital broadcasts. This move is made possible by the production of cheaper, faster and more capable integrated circuits. The chief advantage of digital broadcasts is that they prevent a number of complaints with traditional analogue broadcasts. For television, this includes the elimination of problems such as snowy pictures, ghosting and other distortion. These occur because of the nature of analogue transmission, which means that perturbations due to noise will be evident in the final output. Digital transmission overcomes this problem because digital signals are reduced to discrete values upon reception and hence small perturbations do not affect the final output. In a simplified example, if a binary message 1011 was transmitted with signal amplitudes [1.0 0.0 1.0 1.0] and received with signal amplitudes [0.9 0.2 1.1 0.9] it would still decode to the binary message 1011 — a perfect reproduction of what was sent. From this example, a problem with digital transmissions can also be seen in that if the noise is great enough it can significantly alter the decoded message. Using forward error correction a receiver can- 3 --correct a handful of bit errors in the resulting message but too much noise will lead to incomprehensible output and hence a breakdown of the transmission.In digital television broadcasting, there are three competing standards that are likely to be adopted worldwide. These are the ATSC, DVB and ISDB standards; the adoption of these standards thus far is presented in the captioned map. All three standards use MPEG-2 for video compression. ATSC uses Dolby Digital AC-3 for audio compression, ISDB uses Advanced Audio Coding (MPEG-2 Part 7) and DVB has no standard for audio compression but typically uses MPEG-1 Part 3 Layer 2. The choice of modulation also varies between the schemes. In digital audio broadcasting, standards are much more unified with practically all countries choosing to adopt the Digital Audio Broadcasting standard (also known as the Eureka 147 standard). The exception being the United States which has chosen to adopt HD Radio. HD Radio, unlike Eureka 147, is based upon a transmission method known as in-band on-channel transmission that allows digital information to "piggyback" on normal AM or FM analogue transmissions.However, despite the pending switch to digital, analogue receivers still remain widespread. Analogue television is still transmitted in practically all countries. The United States had hoped to end analogue broadcasts on December 31, 2006; however, this was recently pushed back to February 17, 2009. For analogue television, there are three standards in use. These are known as PAL, NTSC and SECAM. For analogue radio, the switch to digital is made more difficult by the fact that analogue receivers are a fraction of the cost of digital receivers. The choice of modulation for analogue radio is typically between amplitude modulation (AM) or frequency modulation (FM). To achieve stereo playback, an amplitude modulated subcarrier is used for stereo FM.The InternetThe Internet is a worldwide network of computers and computer networks that can communicate with each other using the Internet Protocol. Any computer on the Internet has a unique IP address that can be used by other computers to route- 4 --information to it. Hence, any computer on the Internet can send a message to any other computer using its IP address. These messages carry with them the originating computer's IP address allowing for two-way communication. In this way, the Internet can be seen as an exchange of messages between computers.An estimated 16.9% of the world population has access to the Internet with the highest access rates (measured as a percentage of the population) in North America (69.7%), Oceania/Australia (53.5%) and Europe (38.9%).In terms of broadband access, Iceland (26.7%), South Korea (25.4%) and the Netherlands (25.3%) lead the world.The Internet works in part because of protocols that govern how the computers and routers communicate with each other. The nature of computer network communication lends itself to a layered approach where individual protocols in the protocol stack run more-or-less independently of other protocols. This allows lower-level protocols to be customized for the network situation while not changing the way higher-level protocols operate. A practical example of why this is important is because it allows an Internet browser to run the same code regardless of whether the computer it is running on is connected to the Internet through an Ethernet or Wi-Fi connection. Protocols are often talked about in terms of their place in the OSI reference model, which emerged in 1983 as the first step in an unsuccessful attempt to build a universally adopted networking protocol suite.For the Internet, the physical medium and data link protocol can vary several times as packets traverse the globe. This is because the Internet places no constraints on what physical medium or data link protocol is used. This leads to the adoption of media and protocols that best suit the local network situation. In practice, most intercontinental communication will use the Asynchronous Transfer Mode (ATM) protocol (or a modern equivalent) on top of optic fibre. This is because for most intercontinental communication the Internet shares the same infrastructure as the public switched telephone network.- 5 --At the network layer, things become standardized with the Internet Protocol (IP) being adopted for logi cal addressing. For the world wide web, these “IP addresses” are derived from the human readable form using the Domain Name System (e.g.72.14.207.99 is derived from ). At the moment, the most widely used version of the Internet Protocol is version four but a move to version six is imminent.At the transport layer, most communication adopts either the Transmission Control Protocol (TCP) or the User Datagram Protocol (UDP). TCP is used when it is essential every message sent is received by the other computer where as UDP is used when it is merely desirable. With TCP, packets are retransmitted if they are lost and placed in order before they are presented to higher layers. With UDP, packets are not ordered or retransmitted if lost. Both TCP and UDP packets carry port numbers with them to specify what application or process the packet should be handled by. Because certain application-level protocols use certain ports, network administrators can restrict Internet access by blocking the traffic destined for a particular port.Above the transport layer, there are certain protocols that are sometimes used and loosely fit in the session and presentation layers, most notably the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols. These protocols ensure that the data transferred between two parties remains completely confidential and one or the other is in use when a padlock appears at the bottom of your web browser. Finally, at the application layer, are many of the protocols Internet users would be familiar with such as HTTP (web browsing), POP3 (e-mail), FTP (file transfer), IRC (Internet chat), BitTorrent (file sharing) and OSCAR (instant messaging).Local area networksDespite the growth of the Internet, the characteristics of local area networks (computer networks that run at most a few kilometres) remain distinct. This is because networks on this scale do not require all the features associated with larger networks and are often more cost-effective and efficient without them.- 6 --In the mid-1980s, several protocol suites emerged to fill the gap between the data link and applications layer of the OSI reference model. These were Appletalk, IPX and NetBIOS with the dominant protocol suite during the early 1990s being IPX due to its popularity with MS-DOS users. TCP/IP existed at this point but was typically only used by large government and research facilities. As the Internet grew in popularity and a larger percentage of traffic became Internet-related, local area networks gradually moved towards TCP/IP and today networks mostly dedicated to TCP/IP traffic are common. The move to TCP/IP was helped by technologies such as DHCP that allowed TCP/IP clients to discover their own network address —a functionality that came standard with the AppleTalk/IPX/NetBIOS protocol suites.It is at the data link layer though that most modern local area networks diverge from the Internet. Whereas Asynchronous Transfer Mode (ATM) or Multiprotocol Label Switching (MPLS) are typical data link protocols for larger networks, Ethernet and Token Ring are typical data link protocols for local area networks. These protocols differ from the former protocols in that they are simpler (e.g. they omit features such as Quality of Service guarantees) and offer collision prevention. Both of these differences allow for more economic set-ups.Despite the modest popularity of Token Ring in the 80's and 90's, virtually all local area networks now use wired or wireless Ethernet. At the physical layer, most wired Ethernet implementations use copper twisted-pair cables (including the common 10BASE-T networks). However, some early implementations used coaxial cables and some recent implementations (especially high-speed ones) use optic fibres. Optic fibres are also likely to feature prominently in the forthcoming 10-gigabit Ethernet implementations. Where optic fibre is used, the distinction must be made between multi-mode fibre and single-mode fibre. Multi-mode fibre can be thought of as thicker optical fibre that is cheaper to manufacture but that suffers from less usable bandwidth and greater attenuation (i.e. poor long-distance performance).- 7 --电信现代运营电话在一个模拟电话网络, 来电者通过交换机与对方进行不同的电话交流｡开关在两用户间形成一个电气连接,其参数是由来电者按键时的电气特性决定的｡一旦连接,来电者的声音通过来电端处的电话听筒转化为电信号｡然后电信号通过网络发送到另一端的用户,并通过小型扬声器将信号转化为声音｡有一个单独的电气连接用于进行转换,以使用户交谈｡固定电话,在多数居民区是模拟电话,那就是,发言者的声音,直接决定着信号的电压｡虽然距离短,来电可能会被作为模拟信号的端到端信号处理,越来越多电话服务供应商是适度的在传输前将模拟信号数字化以便传输,之后转为模拟信号以便接收｡它的优势是,数字化语音数据可以从互联网上以数字形式传输,而且可以完全转载于远程通信｡(对比来看,模拟信号无可避免会受到噪声影响｡) 手机已对电话网络产生了重大影响｡移动电话用户现在在许多市场超过了固定线路用户｡手机销量在2005年总额为8.166亿,被一下数字平分,其中亚洲/太平洋(2.04亿),西欧(1.64亿),cemea(中欧,中东和非洲)(1.535亿),北美(1.48亿)和拉丁美洲(1.02亿)｡在从1999年之后的五年时间内新增用户来看,非洲已以58.2 %的增长超过了其他地区的市场｡手机逐渐采用如GSM或W-CDMA这些可以数字化传输语音信号的系统,从而使AMPS这样的模拟系统衰落｡电话通信也隐约地有了戏剧性的变化｡开始运作的TAT-8(跨大西洋传输电缆)始于1988年, 20世纪90年代见证了基于光纤系统的普及｡光纤传输的优势在于其所提供的数据容量的急剧增加｡TAT-8可以传输相当于同轴电缆电话10倍的数据,而现在的光纤能传输25倍于TAT-8的数据｡数据能力的增加是由于几个因素:第一,光纤体积远小于其他竞争技术｡第二,他们不受到串扰这意味着数百条光纤可以很容易地捆绑在一个单一的电缆内｡最后,复用技术的改善导致了单条光纤数据容量的指数增长｡基于现代光纤网络的通信是一项称为异步传输模式( ATM )的协议｡如第二段所说,ATM协议允许为并排的数据传输｡它适用于公共电话网络,因为它建立了通过网络数据通道并以此进行通信｡传输协议基本上是一个用户与网络之间的协议,它规定了网络如何来处理数据;如果网络不能满足条件的传输协议,它不接受连接｡这很重要,因为电话可以通过协议,保证自己的恒定比特率,这将确保来电者的声音,不是延迟的部分或完全切断｡ATM的竞争对手,如多标签交换(MPLS),执行类似的任务,并可望在未来取代ATM｡电台和电视台在一个广播系统,中央高功率广播塔传输高频率的电磁波,到众多的低功率接收器上｡由广播塔发送的高频率波由信号调制且该信号载有视频或音频信息｡接收天线稍作调整，以提取高频率波,解调器用来恢复载有视力或音频信息的信号｡广播信号可以是模拟(信号多种多样,载有信息且连续)或数字(信息作为一套离散值,可以编码)｡广播媒体业正处于发展中一个关键的转折点,许多国家都从模拟发展到数字广播｡此举是可使生产更经济,更快且更能够集成电路｡与传统的模拟广播相比,数字广播最大的优势是,他们防止了一些投诉｡对电视来说,这包括消除问题,如雪花屏,重影和其他失真｡这些发生原因,是因为模拟传输的性质,这意味着噪声干扰会明显影响最后的输出｡数字传输,克服了这个问题,因为接收时数字信号变为离散值,这样小扰动不影响最终输出｡举一个简单的例子,一个二进制信息1011,已与信号的振幅[ 1.0 0.0 1.0 1.0 ]调制,并收到信号的振幅[ 0.9 0.2 1.1 0.9 ]它将仍然解码为二进制信息1011-一个完美原码再现｡从这个例子可以看出,数字传输也由一个问题,如果噪音足够大,它可以大大改变解码信息｡使用前向错误校正接收器可以在最终结果中纠正少数比特错误,但太多的噪音将导致难以理解的输出,因此,传输失败｡在数字电视广播中,有3个相互竞争的标准,很可能是全世界公认的｡它们是ATSC标准,DVB标准和ISDB标准;通过这些标准,到目前为止,应用于标题地图｡所有这三个标准,使用MPEG - 2 视频压缩｡ATSC标准采用杜比数字AC - 3音频压缩,ISDB利用先进音频编码( MPEG - 2的第7部分),而DVB没有音频压缩标准,但通常使用MPEG - 1第3部分第2层｡不同标准所用的调制方式也有所不同｡在数字音频广播中,标准更为统一,几乎所有国家都选择采用数字音频广播的标准(也称为作为尤里卡147标准)｡也有例外,美国已选择采用高清广播｡高清广播,不同于尤里卡147 ,它是基于称为在带内通道传输的传输方法,这使数字化信息,进行“背驮式”AM或FM模拟传输｡然而,尽管数字化迫在眉睫,模拟接收机仍然普遍应用｡模拟电视仍然传送几乎所有国家｡美国希望于2006年12月31日之前结束模拟广播;不过,最近又推到2009年2月17日｡对于模拟电视,有三个标准在使用中｡它们是PAL制式,NTSC制式和SECAM制式｡模拟电台,切换到数字变得更加困难,因为模拟接收器只占数字接收机的一小部分成本｡模拟电台调制方式通常采用AM(幅度调制)或FM(频率调制)｡为实现立体声播放,振幅调制副载波用于立体声调频｡互联网互联网是一个全球计算机组成的网络,也是一种用IP联系在一起的计算机网络｡在互联网上的任何一台计算机都有一个唯一的IP地址,其他计算机可以用其进行路由选择｡因此,在互联网上,任何一台电脑可以通过IP地址传送讯息给任何其他的计算机｡这些带有计算机IP地址的信息,允许计算机之间双向沟通｡这样一来,互联网可以被看作是一个计算机之间信息的交换｡据估计,16.9 %的世界人口已经进入互联网且具有最高访问率(以人口百分比衡量),它们在北美地区(69.7 %),大洋洲/澳大利亚(53.5%)和欧洲(38.9%)｡在宽带接入方面,冰岛(26.7%),韩国(25.4%)和荷兰(25.3 %)世界领先｡互联网的成功,部分是因为协议管理计算机和路由器如何互相沟通｡计算机网络通信本身的性质,有助于分层实现,此时,协议栈中的各个独立协议或多或少独立于其他协议｡这使得低级别的协议适应网络的情况,而不影响高层协议的实现｡一个实际的例子可以说明它的重要性,因为它允许一个互联网浏览器上运行相同的代码，不管运行的计算机连接到互联网是通过以太网还是通过Wi - Fi连接｡协议经常以其在OSI参考模型中的位置命名,1983年为第一步,也是一次不成功的尝试,它试图建立一个普遍采用的网络协议套件｡对于互联网来说,物理介质和数据链路层协议可以不同的数倍包遍历全球｡这是因为互联网对所用的物理介质或数据链路协议没有限制｡这导致媒体和协议的应用,它们最适合本地网络的情况｡在实践中,多数洲际通讯将使用异步转移模式( ATM )协议(或一个现代的替代物)并辅以光纤｡这是因为,对于大多数的洲际通信来说,互联网与公共交换式电话网络一样拥有相同的基础设施｡在网络层,适用于逻辑寻址的IP开始标准化｡在万维网上,这些“IP地址”来自通过域名系统处理的人类可读格式(例如72.14.207.99是来自)中｡目前,使用最广泛的版本的互联网协议是版本 4 ,但向版本六过渡已是迫在眉睫｡在传输层大部分通信采用的是传输控制协议(TCP)或用户数据报协议(UDP)｡TCP是基本协议,每条来自其他计算机的消息均需采用TCP,而UDP只有在有利时才会被采用｡有了TCP,数据包若在它们置于更高层次前丢失或乱序,它们会被重发｡有了UDP,数据包丢失时会乱序,也不会重发｡TCP和UDP数据包携带端口以便指出数据包应交由哪些应用程序或进程｡因为某些应用级协议使用某些端口,网络管理员可以通过阻断某一特定端口为目的端口的传输限制上网｡在传输层之上,有一些协议会用到并适当应用于会话层和表示层,最显着的是安全套接层(SSL)和传输层安全(TLS)协议｡这些协议,确保双方之间传输的数据仍然完全保密并且一方或另一方在使用时,挂锁出现于Web浏览器的底部｡最后,在应用层,有很多的协议为互联网用户所熟悉,如HTTP ( Web浏览) , 的POP3 (电子邮件),FTP (档案传输),IRC (网上聊天),BitTorrent(文件共享)和OSCAR(即时通讯)｡局域网不看互联网的发展, 仅局域网的特点(运行于几公里内的计算机网络)仍然明显｡这是因为这种规模的网络并不需要所有与较大的网络有关的功能,因此往往更具成本效益和高效率｡在二十世纪八十年代中期,几个协议套件的出现,填补了OSI参考模型中数据链路层和应用层之间的空隙｡如AppleTalk,IPX和NetBios与20世纪90年代初占主导地位,因MS-DOS而广受欢迎的协议套件IPX｡而TCP / IP,在这一点上,通常只用于大型政府和研究设施｡随着互联网的受欢迎程度的增长以及较大的流量与互联网逐渐相关,局域网逐步走向TCP / IP｡今天的网络大多用于TCP / IP流量是常见的｡向TCP / IP的转变由如允许的TCP / IP客户发现自己的网络地址的DHCP的技术支撑,而这与A ppleTalk,IPX/和N etBIOS协议套件以其成为标准｡在数据链路层,最现代的局域网偏离互联网｡而异步转移模式(ATM)或多协议标签转换(MPLS)技术是典型的数据链路协议,适用于较大的网络｡以太网和令牌环网是典型的局域网数据链路协议｡这些协议不同于前协议,因为它们更简单(例如,它们省略了服务质量保证等功能) ,并提供碰撞预防｡双方的这些差异,是基于经济成本的考虑｡尽管令牌环在80年代和90年代有了一定的普及,但是现在几乎所有的局域网使用有线或无线以太网｡在物理层,大多数有线以太网实现使用铜双绞线电缆(包括常用的10 Base-T的网络)｡然而,一些早期的实现使用同轴电缆,而最近的一些实现(特别是超高速的)使用光纤｡光纤也可能在即将到来的10千兆以太网的实现中有着出色的表现｡用光纤时,必须对多模光纤和单模光纤加以区分｡对于制造商来说,多模光纤可以被认为是便宜的厚光纤,但只有较少可用的带宽和更大的衰减(即较差的长途性能)｡。
关于煤矿以及Zigbee的外文文献加翻译
摘要-本文介绍并设计了一个新类型的煤矿安全监控系统，它是一种基于ZigBee 技术的无线传感器网络系统。
该系统包括地下和地面两部分。
地下的无线传感器网络由固定节点，移动节点和网关构成。
电脑监控软件部署在地面。
该系统不仅可以实时收集矿井环境数据，也可以通过计算矿工所穿的移动节点来实时定位。
关键词：ZigBee；定位；无线传感器网络；煤矿一、研究现状作为一种重要的能源，煤炭在经济发展中起着举足轻重的作用。
煤矿监控系统是煤矿安全和生产效率高的重要保证[1]。
为了确保安全运行，环境监测节点的安装是非常重要的。
然而，常用的传统监控节点通过有线连接获得与控制系统的通信，这个节点存在布线困难，价格昂贵等缺点。
相比之下，无线传感器网络节点可以很容易地与当前矿井监测网络连接，和良好的兼容性，方便组成煤矿瓦斯监测网络，以适应各种大小煤矿的应用。
由于无线节点是电池供电，所以完全摆脱线缆的束缚，缩短建设周期，可以随时安排使用。
这是一个新的短距离，低复杂度，低功耗，低数据速率，低成本的双向无线通信技术[2]。
现在，无线传感器ZigBee无线通信技术应用于煤矿环境监测系统。
基于ZigBee技术的网络产品的数量和种类很多，但真正的产品可以应用在地下环境中的特殊传感器节点是很少的[3]。
我们设计的系统，是真正能够适用于在井下环境，它通过无线传感器网络节点的安全认证。
同时，由于无线网络的特殊性质，它可以传播无线信号，我们可以很容易地找到工作人员以便对煤矿安全监控提供更多的保护[4]。
二、系统架构该系统是一个软件和硬件综合监控系统的融合。
硬件部分包括无线移动节点和固定节点而被地下隧道部署，它的主要功能是收集煤炭矿山环境的数据和人的位置。
电脑监控软件由VC++设计，是用于以总结和展示每个监控节点中移动节点和固定节点的数据。
他们正在使用的数据由无线传输ZigBee协议传输，由于在固定节点也使用无线数据传输的方法，所以在地下巷道部署变得非常方便。
无线电力传输的电车辆应用-英文
Wireless Power Transfer for Electric Vehicle ApplicationsSiqi Li,Member,IEEE,and Chunting Chris Mi,Fellow,IEEEAbstract—Wireless power transfer(WPT)using magnetic resonance is the technology which could set human free from the annoying wires.In fact,the WPT adopts the same basic theory which has already been developed for at least30 years with the term inductive power transfer.WPT tech-nology is developing rapidly in recent years.At kilowatts power level,the transfer distance increases from several mil-limeters to several hundred millimeters with a grid to load efficiency above90%.The advances make the WPT very attractive to the electric vehicle(EV)charging applications in both stationary and dynamic charging scenarios.This paper reviewed the technologies in the WPT area applicable to EV wireless charging.By introducing WPT in EVs,the obstacles of charging time,range,and cost can be easily mitigated.Battery technology is no longer relevant in the mass market penetration of EVs.It is hoped that researchers could be encouraged by the state-of-the-art achievements,and push forward the further development of WPT as well as the expansion of EV.Index Terms—Dynamic charging,electric vehicle(EV), inductive power transfer(IPT),safety guidelines,stationary charging,wireless power transfer(WPT).I.I NTRODUCTIONF OR energy,environment,and many other reasons,theelectrification for transportation has been carrying out for many years.In railway systems,the electric locomotives have already been well developed for many years.A train runs on a fixed track.It is easy to get electric power from a conductor rail using pantograph sliders.However,for electric vehicles(EVs), the highflexibility makes it not easy to get power in a similar way.Instead,a high power and large capacity battery pack is usually equipped as an energy storage unit to make an EV to operate for a satisfactory distance.Until now,the EVs are not so attractive to consumers even with many government incentive ernment subsidy and tax incentives are one key to increase the market share of EV today.The problem for an electric vehicle is nothing else but the electricity storage technology,which requires a battery which is the bottleneck today due to its unsatisfactory energy density,limited life time and high cost. Manuscript received February2,2014;revised April6,2014;accepted April18,2014.Date of publication April23,2014;date of current ver-sion January29,2015.Recommended for publication by Associate Editor ler.S.Li is with the Department of Electrical Engineering,Kunming Uni-versity of Science and Technology,Kunming650500,China(e-mail: lisiqi@).C. C.Mi is with the Department of Electrical and Computer Engineering,University of Michigan,Dearborn,MI48128USA(e-mail: chrismi@).Color versions of one or more of thefigures in this paper are available online at .Digital Object Identifier10.1109/JESTPE.2014.2319453In an EV,the battery is not so easy to design because of the following requirements:high energy density,high power density,affordable cost,long cycle life time,good safety, and reliability,should be met simultaneously.Lithium-ion batteries are recognized as the most competitive solution to be used in electric vehicles[1].However,the energy density of the commercialized lithium-ion battery in EVs is only 90–100Wh/kg for afinished pack[2].1This number is so poor compared with gasoline,which has an energy density about 12000Wh/kg.To challenge the300-mile range of an internal combustion engine power vehicle,a pure EV needs a large amount of batteries which are too heavy and too expensive. The lithium-ion battery cost is about500$/kWh at the present time.Considering the vehicle initial investment,maintenance, and energy cost,the owning of a battery electric vehicle will make the consumer spend an extra1000$/year on average compared with a gasoline-powered vehicle[1].Besides the cost issue,the long charging time of EV batteries also makes the EV not acceptable to many drivers.For a single charge, it takes about one half-hour to several hours depending on the power level of the attached charger,which is many times longer than the gasoline refueling process.The EVs cannot get ready immediately if they have run out of battery energy. To overcome this,what the owners would most likely do is tofind any possible opportunity to plug-in and charge the battery.It really brings some trouble as people may forget to plug-in andfind themselves out of battery energy later on. The charging cables on thefloor may bring tripping hazards. Leakage from cracked old cable,in particular in cold zones, can bring additional hazardous conditions to the owner.Also, people may have to brave the wind,rain,ice,or snow to plug-in with the risk of an electric shock.The wireless power transfer(WPT)technology,which can eliminate all the charging troublesome,is desirable by the EV owners.By wirelessly transferring energy to the EV,the charging becomes the easiest task.For a stationary WPT system,the drivers just need to park their car and leave.For a dynamic WPT system,which means the EV could be powered while driving;the EV is possible to run forever without a stop. Also,the battery capacity of EVs with wireless charging could be reduced to20%or less compared to EVs with conductive charging.Although the market demand is huge,people were just wondering whether the WPT could be realized efficiently at1Although lithium ion battery can achieve up to200Wh/kg for individual cells,the battery pack requires structure design,cooling,and battery manage-ment systems.The over energy density of a battery pack is much lower than the cell density.2168-6777©2014IEEE.Personal use is permitted,but republication/redistribution requires IEEE permission.See /publications_standards/publications/rights/index.html for more information.a reasonable cost.The research team from MIT published a paper in Science[3],in which60W power is transferred at a2-m distance with the so called strongly coupled magnetic resonance theory.The result surprised the academia and the WPT quickly became a hot research area.A lot of interesting works were accomplished with different kinds of innovative circuit,as well as the system analysis and control[4]–[9].The power transfer path can even be guided using the domino-form repeaters[10],[11].In order to transfer power more efficiently and further,the resonant frequency is usually selected at MHz level,and air-core coils are adopted.When the WPT is used in the EV charging,the MHz frequency operation is hard to meet the power and efficiency criteria.It is inefficient to convert a few to a few hundred kilowatts power at MHz frequency level using state-of-the-art power electronics devices.Moreover,air-core coils are too sensitive to the surrounding ferromagnetic objects.When an air-core coil is attached to a car,the magneticflux will go inside the chassis causing high eddy current loss as well as a significant change in the coil parameters.To make it more practical in the EV charging,ferrite as a magneticflux guide and aluminum plate as a shield are usually adopted in the coil design[12].With the lowered frequency to less than100kHz, and the use of ferrite,the WPT system is no different from the inductive power transfer(IPT)technology which has been developed for many years[13]–[39].In fact,since the WPT is based on the nonradiative and near-field electromagnetic,there is no difference with the traditional IPT which is based on magneticfield coupling between the transmitting and receiving coils.The IPT system has already been proposed and applied to various applications,such as underwater vehicles[32]–[34], mining systems[16],cordless robots in automation production lines[36]–[39],as well as the charging of electric vehicles [13],[14],[25]–[27].Recently,as the need of EV charging and also the progress in technology,the power transfer distance increases from several millimeters to a few hundred millimeters at kilowatts power level[12],[14],[40]–[60].As a proof-of-concept of a roadway inductively powered EV,the Partners for Advance Transit and Highways(PATH)program was conducted at the UC Berkeley in the late1970s[14],[54].A60kW, 35-passanger bus was tested along a213m long track with two powered sections.The bipolar primary track was supplied with1200A,400Hz ac current.The distance of the pickup from the primary track was7.6cm.The attained efficiency was around60%due to limited semiconductor technology.During the last15years,researchers at Auckland University have focused on the inductive power supply of movable objects. Their recent achievement in designing pads for the stationary charging of EV is worth noting.A766mm×578mm pad that delivers5kW of power with over90%efficiency for distances about200mm was reported[48],[55].The achieved lateral and longitudinal misalignment tolerance is 250and150mm,respectively.The knowledge gained from the on-line electric vehicle(OLEV)project conducted at the Korea Advanced Institute of Science and Technology(KAIST) also contributes to the WPT design.Three generations of OLEV systems have been built:a light golf cart as thefirst Fig.1.Typical wireless EV charging system.generation,a bus for the second,and an SUV for the third. The accomplishment of the second and the third is noteworthy: 60kW power transfer for the buses and20kW for the SUVs with efficiency of70%and83%,respectively;allowable vertical distance and lateral misalignment up to160mm and up to200mm,respectively[56],[57].In the United States, more and more public attention was drawn to the WPT since the publication of the2007Science paper[3].The WiTricity Corporation with technology from MIT released their WiT-3300development kit,which achieves90%efficiency over a 180mm gap at3.3kW output.Recently,a wireless charging system prototype for EV was developed at Oak Ridge National Laboratory(ORNL)in the United States.The tested efficiency is nearly90%for3kW power delivery[53].The research at the University of Michigan–Dearborn achieved a200mm distance,8kW WPT system with dc to dc efficiency as high as95.7%[61].From the functional aspects,it could be seen that the WPT for EV is ready in both stationary and dynamic applications.However,to make it available for large-scale commercialization,there is still abundant work to be done on the performance optimization,setup of the industrial standards, making it more cost effective,and so on.This paper starts with the basic WPT theory,and then gives a brief overview of the main parts in a WPT system, including the magnetic coupler,compensation network,power electronics converter,study methodology,and its control,and some other issues like the safety considerations.By introduc-ing the latest achievements in the WPT area,we hope the WPT in EV applications could gain a widespread acceptance in both theoretical and practical terms.Also,we hope more researchers could have an interest and make more brilliant contributions in the developing of WPT technology.II.F UNDAMENTAL T HEORYA typical wireless EV charging system is shown in Fig.1. It includes several stages to charge an EV wirelessly.First, the utility ac power is converted to a dc power source by an ac to dc converter with power factor correction.Fig.2.General two-coil WPT system.Then,the dc power is converted to a high-frequency ac todrive the transmitting coil through a compensation network.Considering the insulation failure of the primary side coil,a high-frequency isolated transformer may be inserted betweenthe dc-ac inverter and primary side coil for extra safety andprotection.The high-frequency current in the transmitting coilgenerates an alternating magneticfield,which induces an acvoltage on the receiving coil.By resonating with the secondarycompensation network,the transferred power and efficiencyare significantly improved.At last,the ac power is rectifiedto charge the battery.Fig.1shows that a wireless EV chargerconsists of the following main parts:1)the detached(or separated,loosely coupled)transmittingand receiving ually,the coils are built withferrite and shielding structure,in the later sections,theterm magnetic coupler is used to represent the entirety,including coil,ferrite,and shielding;2)the compensation network;3)the power electronics converters.The main difference between a wireless charger and aconventional conductive or wired charger is that a transformeris replaced by a set of loosely couple coils.To give a quickidea of the WPT principle,the coil and the compensationnetwork are pulled out separately,as shown in Fig.2,whereL1represents the self-inductance of the primary side transmit-ting coil and L2represents the self-inductance of the receivingcoil;˙I1and˙I2are the current in the two coils;˙U12is thevoltage in the secondary coil that is induced by the currentin the primary side coil.˙U21is the voltage in the primarycoil that is induced by the current in secondary side coil dueto coupling,or mutual inductance between the primary andsecondary coils.S1and S2are the apparent power goes intoL1and L2,respectively.S3and S4are the apparent powerprovided by the power converter.S12and S21represent theapparent power exchange between the two coils.The form ofthe compensation network is not specified.The characteristicsof the compensation network will be discussed later.As shown in Fig.2,neglecting the coil resistance andmagnetic losses,we can calculate the simplified form ofexchanged complex power from L1to L2˙S12=−˙U12˙I∗2=−jωM˙I1˙I∗2=ωM I1I2sinϕ12−jωM I1I2cosϕ12(1)˙S21=−˙U21˙I∗1=−jωM˙I2˙I∗1=−ωM I1I2sinϕ12−jωM I1I2cosϕ12(2)where I1and I2are the root mean square value andϕ12isthe phase difference between˙I1and˙I2.The active powertransfer from the primary side to the secondary side can beexpressed asP12=ωM I1I2sinϕ12.(3)The system shown in Fig.2can transfer active power inboth directions.In the analysis below,we assume the poweris transferred from L1to L2.Whenϕ12=π/2,which means˙I1leads˙I2by a quarter cycle,the maximum power can betransferred from L1to L2.The total complex power goes into the two-coil system is˙S=˙S1+˙S2=jωL1˙I1+ωM˙I2˙I∗1+jωL2˙I2+ωM˙I1˙I∗2=jωL1I21+L2I22+2M I1I2cosϕ12.(4)Therefore,the total reactive power goes into the two-coilsystem isQ=ωL1I21+L2I22+2M I1I2cosϕ12.(5)For a traditional transformer,the reactive power representsthe magnetizing power.Higher magnetizing power bringshigher copper and core loss.To increase the transformerefficiency,the ratio between the active power and reactivepower should be maximized.The ratio is defined byf(ϕ12)=|P12||Q|=ωM I1I2sinϕ12ωL1I21+ωL2I22+2ωM I1I2cosϕ12=k1−cos2ϕ12L1L2I1I2+L2L1I2I1+2k cosϕ21=k1−cos2ϕ12x+1x+2k cosϕ12(6)whereπ/2<ϕ12<πx=L1L2I1I2>0k is the coupling coefficient between L1and L2.To achieve the maximum value of f(ϕ12),we solve thefollowing equations:∂∂ϕ12f(ϕ12)=0,∂2∂2ϕ12f(ϕ12)<0(7)and the solutions arecosϕ12=−2kx+1x,sinϕ12=1−4k2x+1x2.(8)When k is close to1,it is a traditional transformer.In this case,if˙I2is an induced current by˙I1,x will be close to1. Thus,cosϕ12≈−1.The phase difference between˙I1and˙I2 is nearly180°.While for WPT,k is close to0.f(ϕ12)is maximized at sinϕ12=1,at which point the transferred power is also maximized.The phase between˙I1and˙I2is around90°instead of180°.Hence we can see the difference between the tightly and the loosely coupled coils.The degree of coupling affects the design of the compensa-tion network.Taking the series–series topology as an example, there are two ways to design the resonant capacitor.One way is design the capacitor to resonate with the leakage inductance [46],[62]which could achieve a higher f(ϕ12).Another way is to resonate with the coil self-inductance[27],[41],[63] which could maximum the transferred power at a certain coil current.When the coupling is tight with a ferrite,like k>0.5, it is important to increase f(ϕ12)to achieve better efficiency. In this case,resonate with the coil self inductance,which makesϕ12=π/2and lowers f(ϕ12),is not recommended. Otherwise the magnetizing loss may significantly increase. When the capacitor resonates with the leakage inductance,it is like the leakage inductance is compensated.This makes the transformer perform as a traditional one and increases f(ϕ12). However,the overall system does not work at a resonant mode.When the coupling is loose,like k<0.5,which is the case for the EV wireless charging,usually the capacitor is tuned with the self inductance to make the system working at a resonate mode to achieve maximum transferred power at a certain coil current.In this case,most of the magnetic field energy is stored in the large air gap between the two coils.The hysteresis loss in the ferrite is not so relative to the magnetizing power.However,the loss in the copper wire is proportional to the square of the conducting current. To efficiently transfer more power at a certain coil current,the induced current˙I2should lag˙I1by90°.Since the induced voltage˙U12on the receiving coil lags˙I1by90°,˙U12and˙I2 should be in phase.The secondary side should have a pure resistive characteristic seen from˙U12at the frequency of˙I1. At the meanwhile,the primary side input apparent power S3 should be minimized.At cosϕ12=0,the complex power˙S1is˙S1=jωL1I21+ωM I1I2.(9) Ideally,the primary side compensation network should cancel the reactive power and make S3=ω0M I1I2,where ω0is the resonant frequency.From the above analysis,we see for a certain transferred power,it is necessary to make the secondary side resonant to reduce the coil volt-ampere(V A) rating,which reduces the loss in the coils;and to make the primary side resonant to reduce the power electronics converter V A rating,which reduces the loss in the power converter. Therefore,we transfer power at the magnetic resonance. With the above analysis,we can calculate the power transfer efficiency between the two coils at the resonant frequency.We haveU12=I2(R2+R Le)=ωM I1=ωkL1L2I1(10) where R2is the secondary winding resistance and R Le is the equivalent load resistance.By defining the quality factor of the two coils, Q1=ωL1/R1,Q2=ωL2/R2,the transferred efficiency can be expressed asη=I22R LeI21R1+I22R2+I22R Le=R Le(R2+R Le)2k2Q1Q2R2+R2+R Le.(11)By defining a=R Le/R2,we obtain the expression of efficiency as a function of aη(a)=1a+1a+2k2Q1Q2+1a+1.(12)The maximum efficiency is obtained by solving the follow-ing equations:∂∂aη(a)=0,∂2∂2aη(a)<0.(13) The maximum efficiencyηmax=k2Q1Q21+1+k2Q1Q22is achieved at aηmax=1+k2Q1Q21/2.In[64],the maximum efficiency is also derived based on several different kinds of compensation network.The results are identical and accord with the above results.The analysis here does not specify a particular compensation form.It can be regarded as a general formula to evaluate the coil performance and estimate the highest possible power transfer efficiency. In EV wireless charging applications,the battery is usu-ally connected to the coil through a diode-bridge rectifier. Most of the time,there is some reactive power required. The reactive power can be provide by either the coil or the compensation network like a unit-power-factor pickup.The battery could be equivalent to a resistance R b=U b/I b,where U b and I b is the battery voltage and current,respectively. If the battery is connected to the rectifier directly in a series-series compensation form,the equivalent ac side resistance could be calculated by R ac=8/π2·R b.Thus,a battery load could be converted to a resistive load.The R ac equation is different for different battery connection style,like with or without dc/dc converter,parallel or series compensation. Most of the time,the equivalent R ac could be derived.Some typical equivalent impendence at the primary side is given in paper[42].By calculating the equivalent ac resistances,the above equations could also be applied to a battery load with rectifier.For stationary EV wireless charging,the coupling between the two coils is usually around0.2.If both the sending and receiving coils have a quality factor of300,the theoretical maximum power transfer efficiency is about96.7%.More efficiency calculations under different coupling and quality factors are shown in Fig.3.Fig.3.Theoretical maximum transfer efficiency between two coils.III.M AGNETIC C OUPLER D ESIGNTo transfer power wirelessly,there are at least two magnetic couplers in a WPT system.One is at the sending side,named primary coupler.The other is at the receiving side,named pickup coupler.Depending on the application scenarios,the magnetic coupler in a WPT for an EV could be either a pad or a track form.For higher efficiency,it is important to have high coupling coefficient k and quality factor Q. Generally,for a given structure,the larger the size to gap ratio of the coupler is,the higher the k is;the thicker the wire and the larger the ferrite section area is,the higher the Q is. By increasing the dimensions and materials,higher efficiency can be achieved.But this is not a good engineering approach. It is preferred to have higher k and Q with the minimum dimensions and cost.Since Q equalsωL/R,high frequency is usually adopted to increase the value of Q.The researchers at Massachusetts Institute of Technology(MIT)used a frequency at around10MHz and the coil Q value reached nearly 1000[3].In high power EV WPT applications,the frequency is also increased to have these benefits.In Bolger’s early design,the frequency is only180Hz[13].A few years later, a400Hz frequency EV WPT system was designed by System Control Technology[14].Neither180Hz nor400Hz is high enough for a loosely coupled system.Huge couplers were employed in the two designs.Modern WPT system uses at least10kHz frequency[15].As the technical progress of power electronics,100kHz could be achieved[65]at high power level.The WiTricity Company with the technology from MIT adopts145kHz in their design.In the recent researches and applications,the frequency adopted in an EV WPT system is between20and150kHz to balance the efficiency and cost.At this frequency,to reduce the ac loss of copper coils, Litz wire is usually adopted.Besides the frequency,the coupling coefficient k is sig-nificantly affected by the design of the magnetic couplers, which is considered one of the most important factors in a WPT system.With similar dimensions and materials,different coupler geometry and configuration will have a significant difference of coupling coefficient.A better coupler design may lead to a50%–100%improvement compared with some nonoptimal designs[48].Fig.4.Mainflux path of double-sided and single-sided coupler.(a)Double-sided type.(b)Single-sided type.A.Coupler in the Stationary ChargingIn a stationary charging,the coupler is usually designed in a pad form.The very early couplers are just like a simple split core transformer[19],[38],[56].Usually this kind of design could only transfer power through a very small gap. To meet the requirements for EV charging,the deformations from spilt core transformers and new magnetic coupler forms are presented for large gap power transfer[12],[31],[37],[42], [47]–[50],[66]–[71].According to the magneticflux dis-tribution area,the coupler could be classified as the double-sided and single-sided types.For the double-sided type,theflux goes to both sides of the coupler[12], [31],[67].Aflattened solenoid inductor form is pro-posed in[12]and[67].Because theflux goes through the ferrite like through a pipe,it is also called aflux-pipe coupler.To prevent the eddy current loss in the EV chassis,an aluminum shielding is usually added which bring a loss of1%–2%[12].When the shielding is added, the quality factor of aflux-pipe coupler reduces from 260to86[48].The high shielding loss makes the double-sided coupler not the optimal choice.For the single-sided coupler, most of theflux exists at only one side of the coupler.As shown in Fig.4,the mainflux pathflows through the ferrite in a single-sided coupler.Unlike the double-sided coupler having half of the mainflux at the back,the single-sided coupler only has a leakageflux in the back.This makes the shielding effort of a single-sided type much less.Two typical single-sidedflux type pads are shown in Fig.5. One is a circular unipolar pad[47].Another one is a rectan-gular bipolar pad proposed by University of Auckland,which is also named DD pad[48].Besides the mechanical support material,a single-sided pad is composed of three layers.The top layer is the coil.Below the coil,a ferrite layer is inserted for the purpose of enhancing and guiding theflux.At the bottom is a shielding layer.To transfer power,the two pads are put closed with coil to coil.With the shielding layer, most of the high-frequency alternating magneticflux can be confined in the space between the two pads.A fundamental flux path concept was proposed in theflux pipe paper[67].Fig. 5.Two typical single-sidedflux type pads.(a)Circular pad.(b)DD pad.Theflux path height of a circular pad is about one-fourth ofthe pad’s diameter.While for a DD pad,the height is abouthalf of the pad’s length.For a similar size,a DD pad has asignificant improvement in the coupling.The charge zone fora DD pad could be about two times larger than a circular padwith similar material cost.The DD pad has a good tolerant inthe y-direction.This makes the DD pad a potential solutionfor the dynamic charging when the driving direction is alongwith the y-axis.However,there is a null point for DD pad inthe x-direction at about34%misalignment[48].To increasethe tolerant in x-direction,an additional quadrature coil namedQ coil is proposed to work together with the DD pad,whichis called DDQ pad[48],[49],[68].With a DDQ receivingpad on a DD sending pad,the charge zone is increased tofivetimes larger than the circular configuration.As the additionalQ coil in the receiver side,the DDQ over DD configurationuses almost two times copper compared with the circularone[48].A variant of a DDQ pad,which is called a newbipolar pad,was also proposed by University of Auckland[49],[50].By increasing the size of each D pad and havingsome overlap between the two D coils,the new bipolar padcould have a similar performance of a DDQ pad with25%less copper.With all the efforts,at200mm gap,the cou-pling between the primary and secondary pads could achieve0.15–0.3with an acceptable size for an EV.Referred to Fig.3,at this coupling level,efficiency above90%could possibly beachieved.B.Coupler in the Dynamic ChargingThe dynamic charging,also called the OLEVs[56]orroadway powered electric vehicles[14],is a way to chargethe EV while driving.It is believed that the dynamic chargingcan solve the EVs’range anxiety,which is the main reasonlimits the market penetration of EVs.In a dynamic chargingsystem,the magnetic components are composed of a primaryside magnetic coupler,which is usually buried under the road,and a secondary side pickup coil,which is mounted under anEV chassis.There are mainly two kinds of primary magneticcoupler in the dynamic charging.Thefirst kind is a long trackcoupler[26],[31],[57],[70],[72]–[76].When an EV withaFig.6.Top view of W-shape and I-shape track configuration.pickup coil is running along with the track,continues powercan be transferred.The track can be as simple as just twowires[37],[77],or an adoption of ferrites with U-type orW-type[26],[56]to increase the coupling and power trans-fer distance.Further,a narrow-width track design with anI-type ferrite was proposed by KAIST[72],[73].The dif-ferences between the W-type and I-type are shown in Fig.6.For W-type configuration,the distribution area of the ferrite Wdetermines the power transfer distance,as well as the lateraldisplacement.The total width of W-type should be about fourtimes the gap between the track and the pickup coil.For I-typeconfiguration,the magnetic pole alternates along with the road.The pole distance W1is optimized to achieve better coupling atthe required distance.The width of pickup coil W2is designedto meet the lateral misalignment requirement.The relationbetween track width and transfer distance is decoupled andthe track can be built at a very narrow form.The width forU-type and W-type is140and80cm,respectively[73].ForI-type,it could be reduced to only10cm with a similar powertransfer distance and misalignment capacity.35kW power wastransferred at a200mm gap and240mm displacement usingthe I-type configuration[73].With the narrowed design,theconstruction cost could be reduced.Also,the track is far awayfrom the road side,the electromagneticfield strength exposedto pedestrians can also be reduced.The problem of the track design is that the pickup coil onlycovers a small portion of the track,which makes the couplingcoefficient very small.The poor coupling brings efficiencyand electromagnetic interference(EMI)issues.To reduce theEMI issue,the track is built by segments[52],[70],[75]with a single power converter and a set of switches to powerthe track.The excitation of each segment can be controlledby the switches’ON-OFF state.The electromagneticfieldabove the inactive segments is reduced significantly.However,there is always a high-frequency currentflowing through thecommon supply cables,which lowers the system efficiency.The published systems efficiency is about70%–80%,whichis much lower than the efficiency achieved in the stationarycharging.When each segment is short enough,the track becomes likea pad in the stationary charging,which is the other kind ofthe primary magnetic coupler.Each pad can be driven by anindependent power converter.Thus,the primary pads can beselectively excited without a high-frequency common current.Also,the energized primary pad is covered by the vehicle.Theelectromagneticfield is shielded to have a minimum impact。
无线功率传输概念说明书
Volume 1 – No. 13100Wireless Power Transmission – A Next Generation PowerTransmission SystemS. Sheik MohammedFaculty of Engineering, Dhofar University, PB No.2509 Salalah, Sultanate of Oman.K. RamasamyProfessorKamaraj College of Engg. andTech., Virudunagar, Tamilnadu, IndiaT. ShanmugananthamProfessor and HeadPerunthalaivar Kamarajar Inst. of Engg .and Tech., Karaikal, (Govt. of Pondicherry Institution), IndiaABSTRACTIn this paper, we present the concept of transmitting power without using wires i.e., transmitting power as microwaves from one place to another is in order to reduce the transmission and distribution losses. This concept is known as Microwave Power transmission (MPT). We also discussed the technological developments in Wireless Power Transmission (WPT). The advantages, disadvantages, biological impacts and applications of WPT are also presented.Key WordsMicrowave Power transmission (MPT), Nikola Tesla, Rectenna, Solar Power Satellites (SPS), Wireless Power transmission (WPT).1. INTRODUCTIONOne of the major issue in power system is the losses occurs during the transmission and distribution of electrical power. As the demand increases day by day, the power generation increases and the power loss is also increased. The major amount of power loss occurs during transmission and distribution. The percentage of loss of power during transmission and distribution is approximated as 26%. The main reason for power loss during transmission and distribution is the resistance of wires used for grid. The efficiency of power transmission can be improved to certain level by using high strength composite over head conductors and underground cables that use high temperature super conductor. But, the transmission is still inefficient. According to the World Resources Institute (WRI), India’s electricity grid has the highest transmission and distribution losses in the world – a whopping 27%. Numbers published by various Indian government agencies put that number at 30%, 40% and greater than 40%. This is attributed to technical losses (grid’s inefficiencies) and theft [1].Any problem can be solved by state–of-the-art technology. The above discussed problem can be solved by choose an alternative option for power transmission which could provide much higher efficiency, low transmission cost and avoid power theft. Microwave Power Transmission is one of the promising technologies and may be the righteous alternative for efficient power transmission.2. WIRELESS POWER TRANSMISSIONNikola Tesla he is who invented radio and shown us he is indeed the “Father of Wireless”. Nikola Tesla is the one who first conceivedthe idea Wireless Power Transmission and demonstrated “the transmission of electrical energy without wires" that depends upon electrical conductivity as early as 1891[2]. In 1893, Tesla demonstrated the illumination of vacuum bulbs without using wires for power transmission at the World Columbian Exposition in Chicago. The Wardenclyffe tower shown in Figure 1 was designed and constructed by Tesla mainly for wireless transmission of electrical power rather than telegraphy [3].Figure1.The 187-foot Wardenclyffe Tower(Tesla Tower)In 1904, an airship ship motor of 0.1 horsepower is driven by transmitting power through space from a distance of least 100 feet [4]. In 1961, Brown published the first paper proposing microwave energy for power transmission, and in 1964 he demonstrated a microwave-powered model helicopter that received all the power needed for flight from a microwave beam at 2.45 GHz [5] from the range of 2.4GHz – 2.5 GHz frequency band which is reservedVolume 1 – No. 13101for Industrial, Scientific, and Medical (ISM) applications. Experiments in power transmission without wires in the range of tens of kilowatts have been performed at Goldstone in California in 1975 [6] and at Grand Bassin on Reunion Island in 1997 [7] . The world’s first MPT experiment in the ionosphere called the MINIX (Microwave Ionosphere Non-linear Interaction Experiment) rocket experiment is demonstrated in 1983 at Japan [8]. Similarly, the world’s first fuel free airplane powered by microwave energy from ground was reported in 1987 at Canada. This system is called SHARP (Stationary High – Altitude Relay Platform) [9].In 2003, Dryden Flight Research Centre of NASA demonstrated a laser powered model airplane indoors. Japan proposed wireless charging of electric motor vehicles by Microwave Power Transmission in 2004. Powercast, a new company introduced wireless power transfer technology using RF energy at the 2007 Consumer Electronics Show [10]. A physics research group, led by Prof. Marin Soljačić, at the Massachusetts Institute of technology (MIT) demonstrated wireless powering of a 60W light bulb with 40% efficiency at a 2m (7ft) distance using two 60cm-diameter coils in 2007 [11]. Recently in 2008, Intel reproduced the MIT group's experiment by wirelessly powering a light bulb with 75% efficiency at a shorter distance [12].2.2 Wireless Power Transmission SystemWilliam C. Brown, the pioneer in wireless power transmission technology, has designed, developed a unit and demonstrated to show how power can be transferred through free space by microwaves. The concept of Wireless Power Transmission System is explained with functional block diagram shown in Figure 2. In the transmission side, the microwave power source generates microwave power and the output power is controlled by electronic control circuits. The wave guide ferrite circulator which protects the microwave source from reflected power is connected with the microwave power source through the Coax – Waveguide Adaptor. The tuner matches the impedance between the transmitting antenna and the microwave source. The attenuated signals will be then separated based on the direction of signal propagation by Directional Coupler. The transmitting antenna radiates the power uniformly through free space to the rectenna.In the receiving side, a rectenna receives the transmitted power and converts the microwave power into DC power. The impedance matching circuit and filter is provided to setting the output impedance of a signal source equal to the rectifying circuit. The rectifying circuit consists of Schottky barrier diodes converts the received microwave power into DC power.2.3 Components of WPT SystemThe Primary components of Wireless Power Transmission are Microwave Generator, Transmitting antenna and Receiving antenna (Rectenna). The components are described in this chapter.2.3.1Microwave GeneratorThe microwave transmitting devices are classified as Microwave Vacuum Tubes (magnetron, klystron, Travelling Wave Tube (TWT), and Microwave Power Module (MPM)) and Semiconductor Microwave transmitters (GaAs MESFET, GaN pHEMT, SiC MESFET, AlGaN/GaN HFET, and InGaAS). Magnetron is widely used for experimentation of WPT. Themicrowave transmission often uses 2.45GHz or 5.8GHz of ISM band. The other choices of frequencies are 8.5 GHz [13], 10 GHz [14] and 35 GHz [15]. The highest efficiency over 90% is achieved at 2.45 GHz among all the frequencies [15].2.3.2 Transmitting AntennaThe slotted wave guide antenna, microstrip patch antenna, and parabolic dish antenna are the most popular type of transmitting antenna. The slotted waveguide antenna is ideal for power transmission because of its high aperture efficiency (> 95%) and high power handling capability.2.3.3 RectennaThe concept, the name ‘rectenna’ and the rectenna was conceived by W.C. Brown of Raytheon Company in the early of 1960s [16]. The rectenna is a passive element consists of antenna, rectifying circuit with a low pass filter between the antenna and rectifying diode. The antenna used in rectenna may be dipole, Yagi – Uda, microstrip or parabolic dish antenna. The patch dipole antenna achieved the highest efficiency among the all. The performance of various printed rectenna is shown in Table I. Schottky barrier diodes (GaAs-W, Si, and GaAs) are usually used in the rectifying circuit due to the faster reverse recovery time and much lower forward voltage drop and good RF characteristics. The rectenna efficiency for various diodes at different frequency is shown in Table II.3. ADVANTAGES, DISADVANTAGES,AND BIOLOGICAL IMPACTS OF WPT3.1 AdvantagesWireless Power Transmission system would completely eliminates the existing high-tension power transmission line cables, towers and sub stations between the generating station and consumers and facilitates the interconnection of electrical generation plants on a global scale. It has more freedom of choice of both receiver and transmitters. Even mobile transmitters and receivers can be chosen for the WPT system. The cost of transmission and distribution become less and the cost of electrical energy for the consumer also would be reduced. The power could be transmitted to the places where the wired transmission is not possible. Loss of transmission is negligible level in the Wireless Power Transmission; therefore, the efficiency of this method is very much higher than the wired transmission. Power is available at the rectenna as long as the WPT is operating. The power failure due to short circuit and fault on cables would never exist in the transmission and power theft would be not possible at all.3.2 DisadvantagesThe Capital Cost for practical implementation of WPT seems to be very high and the other disadvantage of the concept is interference of microwave with present communication systems.3.3 Biological ImpactsCommon beliefs fear the effect of microwave radiation. But the studies in this domain repeatedly proves that the microwave radiation level would be never higher than the dose received while opening the microwave oven door, meaning it is slightly higherVolume 1 – No. 13102than the emissions created by cellular telephones[17]. Cellular telephones operate with power densities at or below the ANSI/IEEE exposure standards [18]. Thus public exposure to WPT fields would also be below existing safety guidelines.Figure 2. Functional Block Diagram of Wireless Power Transmission SystemTable 1. Performance of Printed RectennaType of Rectenna Operating Frequency (GHz) Measured Peak Conversion Efficiency (%)Printed Dipole [9] 2.45 85 Circular Patch[19] 2.45 81Printed dual rhombic [22] 5.6 78 Square patch [15]8.5166Table 2. Rectenna Efficiency for Various Diodes at Different FrequencyFrequency (GHz) Schottky Diode Measured Efficiency (%) Calculated Efficiency(%)2.45 [13] GaAs-W 92.5 90.5 5.8 [19] Si 82 78.3 8.51[20] GaAs 62.5 66.24. APPLICATIONS OF WPTGenerating power by placing satellites with giant solar arrays in Geosynchronous Earth Orbit and transmitting the power as microwaves to the earth known as Solar Power Satellites (SPS) is the largest application of WPT. Another application of WPT is moving targets such as fuel free airplanes, fuel free electric vehicles, moving robots and fuel free rockets. The other applications of WPT are Ubiquitous Power Source (or) Wireless Power Source, Wireless sensors and RF Power Adaptive Rectifying Circuits (PARC).5. CONCLUSIONThe concept of Microwave Power transmission (MPT) and Wireless Power Transmission system is presented. The technological developments in Wireless Power Transmission (WPT), the advantages, disadvantages, biological impacts and applications of WPT are also discussed.This concept offers greater possibilities for transmitting power with negligible losses and ease of transmission than any invention or discovery heretofore made. Dr. Neville of NASA states “You don’t need cables, pipes, or copper wires to receive power. We can send it to you like a cell phone call – where you want it, when you want it, in real time”. We can expect with certitude that in next few years’ wonders will be wrought by its applications if all the conditions are favourable.6.REFERENCES[1] /2008/07/16/indias-electricity-transmission-and-distribution-losses/[2] Nikola Tesla, My Inventions , Ben Johnston, Ed., Austin, Hart Brothers, p. 91,1982.[3] Nikola Tesla, “The Transmission of Electrical Energy Without Wires as a Means for Furthering Peace,” Electrical World and Engineer . Jan. 7, p. 21, 1905.[4] The Electrician (London), 1904).[5] W.C. Brown, J.R. Mims and N.I. Heenan, “An Experimental Microwave-Powered Helicopter”, 965 IEEE International Convention Record, Vol. 13, Part 5, pp.225-235.[6] Brown., W. C. (September 1984). "TheHistory of PowerTransmission by Radio Waves". Microwave Theory andVolume 1 – No. 13103Techniques, IEEE Transactions on (Volume: 32, Issue: 9 On page(s): 1230- 1242 + ISSN: 0018-9480). /xpl/freeabs_all.jsp?arnumber=1132833. [7]POINT-TO-POINT WIRELESS POWER TRANSPORTATION IN REUNION ISLAND 48th International Astronautical Congress, Turin, Italy, 6-10 October 1997 - IAF-97-R.4.08 J. D. Lan Sun Luk, A. Celeste, P. Romanacce, L. Chane Kuang Sang, J. C. Gatina - University of La Réunion - Faculty of Science and Technology.[8] Matsumoto, H.N. Kaya, I. Kimura, S. Miyatake, M. Nagatomo, and T. Obayashi, MINIX Project toward the Solar Power Satellites --- Rocket experiment of microwave energy transmission and associated plasma physics in the ionosphere, ISAS space energy symposium, pp 69-76, 1986.[9] J.J. Schelesak, A. Alden and T. Ohno, A microwave powered high altitude platform, IEEE MTT-S Int. Symp. Digest, pp - 283-286, 1988.[10] "CES Best of 2007"[11] "Goodbye wires…". MIT News. 2007-06-07. /newsoffice/2007/wireless-0607.html. [12] [13] L.W. Epp, A.R. Khan, H.K. Smith, and R.P. Smith, “A compact dual-polarized 8.51-GHz rectenna for high-voltage (50 V) actuator applications,” IEEE Trans. Microwave Theory Tech., vol. 48, pp. 111-120, 2000.[14] T-WYoo and K. Chang, “Theoretical and experimental development of 10 and 35 GHz rectennas,” IEEE Trans. Microwave Theory Tech., vol. 40, pp. 1259-1266, 1992.[15] P. Koert and J.T. Cha, “35 GHz rectenna development,” in Proc. 1st Annu. Wireless Power Transmission Conf., San Antonio, TX, 1993, pp. 457-466.[16] Brown, W.C, “The History of the Development of the Rectenna” Proc. Of SPS microwave systems workshop, pp.271-280, Jan 1980.[17] (How Micro Ovens Work – A Cooking Oven for the 21st century. By Gabriel Gache)[18] J.C. Lin, “Biological aspects of mobile communication fields,” Wireless Networks , vol. 3, pp. 439-453, 1997.[19]M. Onda,M. Fujita, Y. Fujino, N. Kaya, K. Tomita, andMYamada, “A stratospheric stationary LTAplatform concept and ground-to-vehiclemicrowave power transmission tests,” in 37th AIAA Aerospace Sciences Meeting and Exhibit , Reno, NV, 1999, pp. 1-7.[20] P. Koert and J.T. Cha, “35 GHz rectenna development,” in Proc.1st Annu. Wireless Power Transmission Conf., San Antonio, TX, 1993, pp. 457-466.[21] T.-W. Yoo, “Experimental and theoretical study on 35 GHz RF-to-DC power conversion receiver for millimeter-wave beamed power transmission,” Ph.D. dissertation, Dept. of Electrical Engineering, Texas A&M Univ., Dec. 1993.。
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无线电力传输外文文献翻译(含：英文原文及中文译文)文献出处：Weaver, Bill. " Can't Touch This: Wireless power transmission." 26.3(2009).英文原文Can't touch this - wireless power transmissionWilliam L. WeaverA few years ago, a colleague and I participated in a field trip project organized by the college student group to study the West Orange at the Edison National Historic Site in New Jersey. We visited with the public and participated in a laboratory set up inside a building to understand the development of incandescent light bulbs and film technology. However, what impressed me most was the two complex additional functions.First, it is a research library equipped with all publications of the then US Patent Office. Representatives of scientists and engineers are concerned that marketable products may be useful in creating new technologies. The university is a great place to discover science and technology with it, but Edison's laboratory exists as a company. In the late 19th century, there was no internet connection, so the library took up the laboratory's information repository. Just like today, when the researchers needed information about chemical reactions, a mathematical formula or their most advanced engineering solution and consulted the currentliterature, it was only through paper at the time.By simplifying the adoption of standards, this process is further simplified by the rapid adoption of standards. Since most of the tools and equipment can be developed locally, they can deploy their own standards and create the facility on a multi-acre campus.One of these criteria is the method of distribution of power. The final known power supply for grid development is the famous Edison bulb. The tools used in the early Edison lab were a long axis of rotation like a rear-wheel drive automobile driveshaft made up of a universal cable shaft or a marine vessel. The propeller shaft disperses the potential energy of the entire plant in the form of mechanical energy generated by the boiler.A belt and a simple clutch system are connected to the line shaft and the strength of the lever is enhanced by using a surrounding shaft belt. Over time, the belt was worn out due to excessive friction. However, this technology provides a less complex power distribution method than earlier high-pressure steam and hydraulic systems.Over time, as well as the development of electrical and electronic equipment, high-voltage power supplies and more distribution standards must be used in our production plants, offices and homes in the near future. In the United States, the electricity generated is 60 Hz and is eventually produced at a nominal voltage between 120, 240 and 480 volts.A typical power outlet is specified to accommodate 15 amps of currentand is equipped with three familiar prongs, a vertical and U-shaped ground pin consisting of two paddles. Forward-looking retailers make pins of different shapes and orientations to prevent other incompatible devices from connecting. Unless there are not enough power outlets, plugs or extension cords, the standard three-hole power cord is a ubiquitous device to "plug in" the power distribution system.With the continuous development of technology, mobile and handheld devices we currently have are booming, so battery companies will follow. Physically connecting these small devices to the grid will seriously affect their functionality. It is for this reason that they should exhaust their own power supplies or produce rechargeable batteries. Battery manufacturers quickly develop their own industry standards, including "AA" and "C" units, to reduce the confusion that consumers may have when replacing batteries.Although transistor radios and toy sensors were popular at the beginning of the year, single-use chemical batteries could not provide enough current for devices such as laptops, smart phones and personal entertainment games that have complicated computational requirements. Their rechargeable batteries are incorporated into the equipment and rarely need to be replaced by the user. These device manufacturers can choose how the battery is manufactured, such as size, battery life, and internal configuration capabilities of the device components. This featureof the battery has given manufacturers' industrial designers more rights to differentiate their products in style, look and feel.However, the disadvantage of rechargeable batteries is that they eventually still need to be charged. We can easily connect to the power supply via an AC/DC power adapter. However, it is more difficult to connect the battery to the adapter or "charger" because each battery manufacturer is free to design the battery's shape and interface. what? In the lovely 100-year-old innovation after this, it did not change with the mode it should have.A conspiracy theory may indicate that portable device manufacturers admit that battery chargers are a lucrative source of income. Similar bubble jet printer manufacturers rely on the consumption of ink in the device as a sales channel to make up for the difference between the selling price and the cost. Users pay $25 to $100 to replace the damaged or missing power adapter, which cancels out a service. The "real cost of freedom" in a planned or low-cost laptop phone. An innocent non-conspiratorial theory may be related to the 2000 (Y2K) problem. Programmers wou ldn’t expect much trouble for this device made in a two-digit year to create for the future, and few portable device designers may expect to consume laptops, mobile phones, MP3 players, and digital cameras today. The number of people. These functions may eventually be provided by an independent "super smartphone", but at present,individual charger users are still inconvenient. Chargers also have similar, incompatible problems between devices, and users may cause exchanges to rise or lose devices. If you are using your fifth mobile phone, it is very likely that there will be four outdated chargers on your garage's work bench.In February this year, the European Union Telecommunications Authority (CEPT) and the subsequent European Union (EU) jointly authorized the establishment of the Publicis Group Special Mobile Association (GSMA), which was developed in 2012 as a standard for use by mobile phones. Micro USB interface charger specification. In addition to making the user more convenient, this specification has also been applied to the recycling of discarded adapters. Although it is not aimed at the standardization of adapters between different mobile devices, it seems to be a good start.However, imagine that if the AC/DC adapter is completely eliminated. This is the future of wireless energy transfer. Nikola Tesla first published his utility in 1893. Inductively coupled transformers use wireless technology to replace an ordinary power adapter, correcting the drawbacks of the DC voltage required to charge the two inductive coils of an inductively coupled transformer supplied by an AC outlet. Unfortunately, as the distance between the transmitter and receiver increases, the inductance effect quickly diminishes and is often affectedby interference. In other recent developments, Professor Malinsoor and his colleagues at the Massachusetts Institute of Technology recently developed inductive coupling coils that can be tuned to specific resonant frequencies to overcome these limitations. This improves the understanding of the coupling efficiency of the power supply and reduces the interference around other devices or between coils in other indifferent locations. It is called eCoupled technology.While taking advantage of the high efficiency of the Witricity Resonance Sensing, the eCoupled system, including the sender and receiver, does not include the switching of a metal device or device of the RFID chip into sleep mode. The additional data services are robust and canonical communications, and will automatically power off when the battery is full. If widely adopted, wireless power transmission will be listed as a public service facility. Imagine eCoupled transmitters are simple when it comes to using new standards that are used to spur their own, usually using two main methods. To the new standard, there are usually two main methods used to promote its development. The first is a strong regulatory code. Second, inventing a technology that allows manufacturers to imitate and make it widely popular is powerful, but I prefer the latter's non-intervention method.中文译文不能触碰这个—无线电力传输William L. Weaver几年前, 一个同事和我参加在校大学生团体的组织的一个实地考察项目, 考察地位于新泽西州的爱迪生国家历史遗址的西橙。