Xem 1-20 trên 32 kết quả Wide band
  • Recently an emerging ultra-wide band (UWB) technology is on development. It requires hard design specifications for antennas over a very wide bandwidth. U.S. Federal Communication Commission (FCC) defines UWB as higher than 20% fractional instantaneous bandwidth. Short-pulse UWB technology is applied in communication, radar and precision radiolocation.

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  • In this paper, materials of ZnS:Cu, ZnS:Mn and ZnO:Co were prepared by ceramic method and co-precipitated method. The presence of transition metals such as Cu2+(3d9), Mn2+(3d5) in ZnS and Co2+(3d7) in ZnO make blue bands at around 476 nm, 486 nm and green band at around 514 nm disappeared. Simultaneously, there are luminescence bands at around 533 nm, 582 nm, 693 nm for bulk samples of ZnS:Cu, ZnS:Mn, ZnO:Co and 603 nm for nanocrystalline sample of ZnS:Mn.

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  • We use computers in our daily lives, sometimes becoming so engrossed in the virtual world that we stop being conscious of the computer’s presence. Computers’ increasing capabilities, such as faster processing, larger capacity, and wide-band networking, make it possible for us to interact seamlessly with them. The field of human-computer interaction is the study of interaction between people (users) and computers. It is often regarded as the intersection of computer science, behavioral science, design, psychology, sociology, and several other fields.

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  • 1.Wireless USB là gì ? • Wireless USB là viết tắt của Wireless Universal Serial Bus là chuẩn giao tiếp không dây giữa PC và thiết bị ngoại vi hay giữa các thiết bị ngoại vi với nhau có tốc độ truyền dữ liệu cao . • WUSB được phát triển từ chuẩn giao tiếp USB. Nói cách khác WUSB là chuẩn USB không dây nối. • WUSB và USB dựa trên nền tảng công nghệ băng thông siêu rộng UWB (Ultra Wide Band).

    doc15p nguyenquangha1991 19-12-2012 63 24   Download

  • The Cisco TelePresence System 3000 (CTS-3000) is designed for large group meetings, seating up to 12 participants around a virtual table. It consists of: • Three 65” high definition plasma displays • Three high definition cameras • Three wide band microphones and speakers • A lighting shroud integrated around a purpose built meeting room table Customers must furnish their own chairs. A Cisco 7970G IP phone is used to launch, control, and end the meeting.

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  • 14 Active Vibration Absorption and Delayed Feedback Tuning 14.1 14.2 Nejat Olgac University of Connecticut Introduction Delayed Resonator Dynamic Absorbers The Delayed Resonator Dynamic Absorber with Acceleration Feedback • Automatic Tuning Algorithm for the Delayed Resonator Absorber • The Centrifugal Delayed Resonator Torsional Vibration Absorber Martin Hosek University of Connecticut 14.3 Multiple Frequency ATVA and Its Stability Synopsis • Stability Analysis; Directional Stability Chart Method • Optimum ATVA for Wide-Band Applications 14.

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  • Silicon carbide (SiC) is an interesting material that has found application in a variety of industries. The two best known applications of this material are its use as an abrasive material and its more recent use as a wide band gap semiconductor for high power, high temperature electronic devices. The high hardness of this material, known for many years, led to its use in machining tools and in other structural applications.

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  • Textbooks on radio antennas and propagation have changed little over the last 50 years. Invariably they base themselves on the famous electromagnetic equations described by James Clerk Max- well, a great nineteenth-century genius of theoretical physics (Torrance, 1982). Maxwell's equations brilliantly encompassed all the electromagnetic phenomena known by his time (except photo- electric long-wave cut-off, which remained ...

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  • Highpass and Bandstop Filters In this chapter, we will discuss some typical microstrip highpass and bandstop filters. These include quasilumped element and optimum distributed highpass filters, narrow-band and wide-band bandstop filters, as well as filters for RF chokes. Design equations, tables, and examples are presented for easy reference.

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  • Accurate determination of the mobile position constitutes the basis of many new applications. This book provides a detailed account of wireless systems for positioning, signal processing, radio localization techniques (Time Difference Of Arrival), performances evaluation, and localization applications. The first section is dedicated to Satellite systems for positioning like GPS, GNSS. The second section addresses the localization applications using the wireless sensor networks.

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  • The 71-76 and 81-86 GHz bands (widely known as “e-band”) are permitted worldwide for ultra high capacity point-to-point communications. E-band wireless systems offer full-duplex Gigabit Ethernet connectivity at data rates of 1 Gbps and higher in cost effective radio architectures, with carrier class availability at distances of a mile (1.6 km) and beyond.

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  • When I was first approached to edit a volume on Femtosecond Laser Spectroscopy in 2000, I did not anticipate that the field was about to explode, with the announcement of a series of remarkable new developments and advances. This volume describes these recent developments in eleven chapters written by leading international researchers in the field. It includes sections on: Femtosecond optical frequency combs, which are currently revolutionising ultrahigh precision spectroscopy and optical frequency metrology;...

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  • This second application of the global burden of disease framework permits an analysis of trends observed since the first application. The intervening period was clearly one of slow progress, impeded by the HIV/AIDS epidemic and setbacks in Eastern Europe. The volume is appropriately cautious in draw- ing inferences about disease-specific trends because of changes in data sources and, in some instances, improvements in approaches to measurement.

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  • Computer Networks 1: Lecture 10 (Part 2) - FTP and HTTP presents about FTP - File Transfer Protocol, FTP - Out of Band Control, FTP - Transfer Mode, World Wide Web, WWW Introduction, HTML, Other than HTML, Multithreads, Modern Web Server.

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  • To maximize the extent of the photonic bandgap in a finite-height photonic-crystal (PhC) slab one can increase the fill-factor in the PhC lattice. Among the realistic choices of possible 2D lattices, high fill- factor triangular lattices of cylindrical holes in a high index dielectric, namely silicon, are by far the most commonly used. In this paper, we present a method for fabrication of very high fill-factor PhC devices in silicon-on-insulator (SOI) substrates using electron-beam lithography and high-aspect-ratio reactive-ion etching (RIE).

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  • IELTS Graduation is a comprehensive course for students preparing to take the IELTS academic test. Aimed at the IELTS band 5.5 – 7.5, this topic-based book contains a wide range of activities to train students in all the required skills to help improve their IELTS score. It provides clear and practical information on all parts of the IELTS examination, as well as teaching them the skills required to do well.

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  • FILTER DESIGN A circuit designer frequently requires ®lters to extract the desired frequency spectrum from a wide variety of electrical signals. If a circuit passes all signals from dc through a frequency oc but stops the rest of the spectrum, then it is known as a low-pass ®lter. The frequency oc is called its cutoff frequency. Conversely, a high-pass ®lter stops all signals up to oc and passes those at higher frequencies. If a circuit passes only a ®nite frequency band that does not include zero (dc) and in®nite frequency, then it is called a band-pass ®lter.

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  • Microwaves are generally considered to be a specific part of the wide radio frequency spectrum. The band from 300 MHz to 30 GHz is typically considered to be “microwaves,” for example by the Institute of Electrical end Electronics Engineers (IEEE), although many of us prefer to set the lower limit somewhat higher—perhaps at 1 or even 3 GHz. Above 30 GHz, the term “millimeter waves” is used. High school physics suggests that we are talking about wavelengths ranging from about 30 cm down to 10 mm...

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  • A communication circuit designer frequently requires means to select (or reject) a band of frequencies from a wide signal spectrum. Resonant circuits provide such ®ltering. There are well-developed, sophisticated methodologies to meet virtually any speci®cation. However, a simple circuit suf®ces in many cases. Further, resonant circuits are an integral part of the frequency-selective ampli®er as well as of the oscillator designs. These networks are also used for impedance transformation and matching.

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  • The term ‘microwaves’ is used for those wavelengths measured in centimetres roughly from 1 m. to 0.1 cm or the bands of frequencies between 300 MHz to 300 GHz. Microwaves are most popularly used in point to point communication, TV broadcasting via satellites and in RADAR systems. Besides these, they are also being used in industrial, biomedical, chemical and in scientific research applications.

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