Fordecades,microwavelineofsight(LOS)linkshavebeenoneofthebasictechnolo- gies used to build telephone networks. Until 1980, the fast rollout of high capacity transport networks and deployment of links in areas with challenging geographic Characteristics could not be understood without this technology.
上傳時間： 2020-05-28
上傳用戶：shancjb
At the macroscopic level of system layout, the most important issue is path loss. In the older mobile radio systems that are limited by receiver noise, path loss determines SNR and the maximum coverage area. In cellular systems, where the limiting factor is cochannel interference, path loss determines the degree to which transmitters in different cells interfere with each other, and therefore the minimum separation before channels can be reused.
標(biāo)簽： Characteristics Channel Mobile
上傳時間： 2020-05-30
上傳用戶：shancjb
The ever-increasing demand for private and sensitive data transmission over wireless net- works has made security a crucial concern in the current and future large-scale, dynamic, and heterogeneous wireless communication systems. To address this challenge, computer scientists and engineers have tried hard to continuously come up with improved crypto- graphic algorithms. But typically we do not need to wait too long to find an efficient way to crack these algorithms. With the rapid progress of computational devices, the current cryptographic methods are already becoming more unreliable. In recent years, wireless re- searchers have sought a new security paradigm termed physical layer security. Unlike the traditional cryptographic approach which ignores the effect of the wireless medium, physi- cal layer security exploits the important Characteristics of wireless channel, such as fading, interference, and noise, for improving the communication security against eavesdropping attacks. This new security paradigm is expected to complement and significantly increase the overall communication security of future wireless networks.
標(biāo)簽： Communications Physical Security Wireless Layer in
上傳時間： 2020-05-31
上傳用戶：shancjb
Part I provides a compact survey on classical stochastic geometry models. The basic models defined in this part will be used and extended throughout the whole monograph, and in particular to SINR based models. Note however that these classical stochastic models can be used in a variety of contexts which go far beyond the modeling of wireless networks. Chapter 1 reviews the definition and basic properties of Poisson point processes in Euclidean space. We review key operations on Poisson point processes (thinning, superposition, displacement) as well as key formulas like Campbell’s formula. Chapter 2 is focused on properties of the spatial shot-noise process: its continuity properties, its Laplace transform, its moments etc. Both additive and max shot-noise processes are studied. Chapter 3 bears on coverage processes, and in particular on the Boolean model. Its basic coverage Characteristics are reviewed. We also give a brief account of its percolation properties. Chapter 4 studies random tessellations; the main focus is on Poisson–Voronoi tessellations and cells. We also discuss various random objects associated with bivariate point processes such as the set of points of the first point process that fall in a Voronoi cell w.r.t. the second point process.
標(biāo)簽： Stochastic Geometry Networks Wireless Volume and
上傳時間： 2020-06-01
上傳用戶：shancjb
Intensive development of digital technologies coincided in time with the beginning of the new era in telecommunications. It made possible to formalize many proce- dures of data exchange and to atomize some operations which made providing of serviceandmakeworkofmanytelecommunicationworkersmucheasier. Somenew telecommunication technologies were born out of the necessity for use of specific configurations of network elements and networks, as well as for a possibility of providing maximum Characteristics of efficiency combined with high requirements to the stability of operation, the overcoming of different catastrophic situations and deadlockconditions,such as failuresand ”pending”of the networkandthe like. The thresholdbetweeninformationsystems andtelecommunicationsystems has become practically invisible. It resulted in such a new term as ”infocommunication”
標(biāo)簽： Telecommunication+Systems
上傳時間： 2020-06-01
上傳用戶：shancjb
It has been over a decade since the Chinese publication of Line Loss in Electric Power Systems. To keep pace with technological developments, I started a revision as early as 2002, following the main principles that the theoretical framework and Characteristics of the first edition should be retained, with new contents added according to new problems after the reform of electric power systems and the new requirements for line loss management practices and in combination with practical experience.
上傳時間： 2020-06-07
上傳用戶：shancjb
n present power system, the engineers face variety of challenges in planning, construction and operation. In some of the problems, the engineers need to use managerial talents. In system design or upgrading the entire system into automatic control instead of slow response of human operator, the engineers need to exercise more technical knowledge and experience. It is principally the engi- neer’s ability to achieve the success in all respect and provide the reliable and uninterrupted service to the customers. This chapter covers some important areas of the traditional power system that helps engineers to overcome the challenges. It emphasizes the Characteristics of the various components of a power system such as generation, transmission, distribution, protection and SCADA system. During normal operating conditions and disturbances, the acquired knowledge will pro- vide the engineers the ability to analyse the performance of the complex system and execute future improvement
上傳時間： 2020-06-07
上傳用戶：shancjb
EN 300220-1V2.4.1 Electromagnetic compatibility and Radio spectrum Matters (ERM);Short Range Devices (SRD);Radio equipment to be used in the 25 MHz to 1 000 MHz frequency range with power levels ranging up to 500 mW; Part 1: Technical Characteristics and test methods
標(biāo)簽： EMC
上傳時間： 2021-07-25
上傳用戶：beiyouxia
This paper presents a new type of electromagnetic damper with rotating inertial mass that has been devel oped to control the vibrations of structures subjected to earthquakes. The electromagnetic inertial mass damper (EIMD) consists of a ball screw that converts axial oscillation of the rod end into rotational motion of the internal flflywheel and an electric generator that is turned by the rotation of the inner rod. The EIMD is able to generate a large inertial force created by the rotating flflywheel and a variable damping force devel oped by the electric generator. Device performance tests of reduced-scale and full-scale EIMDs were under taken to verify the basic Characteristics of the damper and the validity of the derived theoretical formulae. Shaking table tests of a three-story structure with EIMDs and earthquake response analyses of a building with EIMDs were conducted to demonstrate the seismic response control performance of the EIMD. The EIMD is able to reduce story drifts as well as accelerations and surpasses conventional types of dampers in reducing acceleration responses.
標(biāo)簽： electromagnetic response Seismic control using
上傳時間： 2021-11-04
上傳用戶：a1293065
在半導(dǎo)體制冷技術(shù)的工作性能及其優(yōu)缺點(diǎn)研究的基礎(chǔ)上,設(shè)計了以單片機(jī)為核心控制元件,以TEC1-12706為執(zhí)行元件的半導(dǎo)體制冷溫度控制系統(tǒng)。采用高精度分段式PID控制算法配合PWM輸出控制的方法實現(xiàn)溫度控制;選擇數(shù)字傳感器DS18B20為溫度檢測元件,還包含1602液晶顯示模塊、按鍵調(diào)整輸入模塊和H橋驅(qū)動模塊等。實際測試表明,該系統(tǒng)結(jié)構(gòu)簡單易行,操作方便,工作性能優(yōu)良,同時針對該系統(tǒng)專門設(shè)計的溫控算法,使半導(dǎo)體制冷器能更好地適應(yīng)不同工況而充分發(fā)揮其制冷制熱工作特性。Based on the study of the performance and advantages and disadvantages of thermoelectric cooler(TEC)technology,a thermoelectric cooling temperature control system with single-chip microcomputer as the core control element and TEC1-12706 as the executive element was designed. High precision piecewise PID control algorithm combined with PWM output control method is adopted to realize temperature control. The digital sensor DS18B20 is selected as the temperature detection element. It also includes 1602 LCD module,key adjustment input module and H bridge drive module. The actual test shows that the system has simple structure,convenient operation and excellent performance. Meanwhile,the temperature control algorithm specially designed for the system can make the semiconductor cooler better adapt to different working conditions and give full play to its refrigeration and heating Characteristics.
標(biāo)簽： 半導(dǎo)體 溫度控制系統(tǒng)
上傳時間： 2022-03-27
上傳用戶：
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