We analyze, both analytically and numerically, the effectiveness of cloaking an infinite cylinder from observations by electromagnetic waves in three dimensions. We show that, as truncated approximations of the ideal permittivity and permeability tensors tend towards the singular ideal cloaking fields, so that the anisotropy ratio tends to infinity, the D and B fields blow up near the cloaking surface. Since the metamaterials used to implement cloaking are based on effective Medium theory, the resulting large variation in D and B will pose a challenge to the suitability of the field averaged characterization of " and 碌. We also consider cloaking with and without the SHS (softand- hard surface) lining, shown in [6] to be theoretically necessary for cloaking in the cylindrical geometry. We demonstrate numerically that cloaking is significantly improved by the SHS lining, with both the far field of the scattered wave significantly reduced and the blow up of D and B prevented.
標(biāo)簽： effectiveness analytically numerically cloaking
上傳時(shí)間： 2017-03-30
上傳用戶：zxc23456789
nTIM PATRICK has been working professionally as a software architect and developer for nearly 25 years. By day he develops custom business applications in Visual Basic for small to Medium- sized organizations. He is a Microsoft Certified Solution Developer (MCSD). In April 2007, Microsoft awarded Tim with its Most Valuable Professional (MVP) award for his work in sup- porting and promoting Visual Basic and its community of users. Tim received his under- graduate degree in computer science from Seattle Pacific University. You can contact him through his web site, www.timaki.com.
標(biāo)簽： professionally architect developer software
上傳時(shí)間： 2013-12-26
上傳用戶：asdfasdfd
Digital Modulation Techniques are those echniques through which we convert digital signals into analog signal which can be transmitted through transmission Medium...this program demostrate some of the basics techniques
標(biāo)簽： Modulation Techniques echniques Digital
上傳時(shí)間： 2013-12-23
上傳用戶：wyc199288
Writing essays and dissertations can be a major concern for overseas students studying at English-Medium colleges and universities. Virtually all courses contain a large degree of written assessment and it is essential to ensure that your writing skills meet the necessary standard. Academic Writing is a new kind of writing course for all international students who have to write exams or coursework in English. This practical book thoroughly explains the writing process and covers all the key writing skills.
標(biāo)簽： Academic writing
上傳時(shí)間： 2015-11-13
上傳用戶：blackbat
msp430The LDC1312 and LDC1314 are 2- and 4-channel, 1? Easy-to-use – minimal configuration required 12-bit inductance to digital converters (LDCs) for ? Measure up to 4 sensors with one IC inductive sensing solutions. With multiple channels ? Multiple channels support environmental and and support for remote sensing, the LDC1312 and aging compensation LDC1314 enable the performance and reliability benefits of inductive sensing to be realized at minimal? Multi-channel remote sensing provides lowest cost and power. The products are easy to use, onlysystem cost requiring that the sensor frequency be within 1 kHz ? Pin-compatible Medium and high-resolution and 10 MHz to begin sensing. The wide 1 kHz to 10 options MHz sensor frequency range also enables use of very small PCB coils, further reducing sensing– LDC1312/4: 2/4-ch 12-bit LDC solution cost and size.– LDC1612/4: 2/4-ch 28
上傳時(shí)間： 2016-07-22
上傳用戶：tongmoonsky
The capability of radio waves to provide almost instantaneous distant communications without interconnecting wires was a major factor in the explosive growth of communica- tions during the 20th century. With the dawn of the 21st century, the future for communi- cations systems seems limitless. The invention of the vacuum tube made radio a practical and affordable communications Medium.
標(biāo)簽： Communications Receivers
上傳時(shí)間： 2020-05-26
上傳用戶：shancjb
This thesis is about wireless communication in shared radio spectrum. Its origin and motivation is ideally represented by the two quotations from above. In this thesis, the support of Quality-of-Service (QoS) in cognitive radio networks is analyzed. New approaches to distributed coordination of cognitive radios are developed in different spectrum sharing scenarios. The Wireless Local Area Network (WLAN) 802.11 proto- col of the Institute of Electrical and Electronics Engineers (IEEE) (IEEE, 2003) with its enhancement for QoS support (IEEE, 2005d) is taken as basis. The Medium Access Control (MAC) of 801.11(e) is modified to realize flexible and dynamic spectrum assignment within a liberalized regulation framework.
標(biāo)簽： Quality-of-Service Distributed Support
上傳時(shí)間： 2020-05-27
上傳用戶：shancjb
Wireless is one of the most rapidly developing technologies in our time, with dazzling new products and services emerging on an almost daily basis. These developments present enormous challenges for communications engineers, as the demand for increased wireless capacity grows explosively. Indeed, the discipline of wireless communications presents many challenges to designers that arise as a result of the demanding nature of the physical Medium and the complexities in the dynamics of the underlying network.
標(biāo)簽： Communications Wireless MIMO
上傳時(shí)間： 2020-05-28
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(shí)間： 2020-05-31
上傳用戶：shancjb
Wireless networking is undergoing a transformation from what has been primarily a Medium for supporting voice traffic between telephones, into what is increasingly becoming a Medium for supporting traffic among a variety of digital devices transmitting media of many types (voice, data, images, video. etc.) Wireline networking underwent a similar transformation in the 1990s, which led to an enormous build-up in the capacity of such networks, primarily through the addition of new optical fiber, switches and other infrastructure.
標(biāo)簽： Multiusers Detection Wireless Networks
上傳時(shí)間： 2020-06-01
上傳用戶：shancjb
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