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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.
標簽：
Microwave
Line
上傳時間：
2020-05-28
上傳用戶：shancjb
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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.
標簽：
characteristics
Channel
Mobile
上傳時間：
2020-05-30
上傳用戶：shancjb
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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.
標簽：
Communications
Physical
Security
Wireless
Layer
in
上傳時間：
2020-05-31
上傳用戶：shancjb
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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.
標簽：
Stochastic
Geometry
Networks
Wireless
Volume
and
上傳時間：
2020-06-01
上傳用戶：shancjb
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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”
標簽：
Telecommunication+Systems
上傳時間：
2020-06-01
上傳用戶：shancjb
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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.
標簽：
Analysis
Line
Loss
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
標簽：
Smart
Grids
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
標簽：
EMC
上傳時間：
2021-07-25
上傳用戶：beiyouxia
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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.
標簽：
electromagnetic
response
Seismic
control
using
上傳時間：
2021-11-04
上傳用戶：a1293065
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在半導體制冷技術的工作性能及其優缺點研究的基礎上,設計了以單片機為核心控制元件,以TEC1-12706為執行元件的半導體制冷溫度控制系統。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溫度控制;選擇數字傳感器DS18B20為溫度檢測元件,還包含1602液晶顯示模塊、按鍵調整輸入模塊和H橋驅動模塊等。實際測試表明,該系統結構簡單易行,操作方便,工作性能優良,同時針對該系統專門設計的溫控算法,使半導體制冷器能更好地適應不同工況而充分發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.
標簽：
半導體
溫度控制系統
上傳時間：
2022-03-27
上傳用戶：
