It was proposed that perfect invisibility cloaks can be constructed for hiding objects from electromagnetic
illumination (Pendry et al., Science 312, p. 1780). The cylindrical cloaks experimentally
demonstrated (Schurig et al., Science 314, p. 997) and theoretically proposed (Cai et al., Nat. Photon.
1, p. 224) have however simplified material parameters in order to facilitate easier Realization
as well as to avoid infinities in optical constants. Here we show that the cylindrical cloaks with
simplified material parameters inherently allow the zeroth-order cylindrical wave to pass through
the cloak as if the cloak is made of a homogeneous isotropic medium, and thus visible. To all
high-order cylindrical waves, our numerical simulation suggests that the simplified cloak inherits
some properties of the ideal cloak, but finite scatterings exist.
標簽：
invisibility
constructed
proposed
electrom
上傳時間：
2013-12-18
上傳用戶：13215175592
搶答器是一種智力競賽常用的器件,搶答器的設計方法千差萬別,文章利用常用的數字電子器件,設計了八路搶答器電路的設計、仿真及實現的全過程,提出兩種可行的設計方案:方案1采用74ls373實現電路鎖存,74ls148實現電路編碼,74ls74及數碼管實現電路顯示;方案二采用CD4511BCN和LMC555CM集成電路及數碼管實現搶答器的控制和顯示。本文設計用的器件簡單,容易理解,適用于初學電子技術的人員。Answer scrambler is a common device in intelligence competition, and its design methods vary greatly. This paper designs the whole process of design, simulation and Realization of the circuit of eight-way answer scrambler by using common digital electronic devices, and puts forward two feasible design schemes: scheme 1 uses 74 ls373 to realize circuit latching, 74 ls148 to realize circuit coding,74 ls74 and digital tube to realize circuit. The second scheme uses CD4511 BCN, LMC555 CM integrated circuit and digital tube to control and display the answerer. The device designed in this paper is simple and easy to understand, and it is suitable for the beginners of electronic technology.
標簽：
搶答器
上傳時間：
2022-04-05
上傳用戶：
本文設計了一種磁致伸縮位移傳感器,介紹了該磁致伸縮位移傳感器的測量原理,通過結構優化設計提高了儀器的性能,詳述了硬件電路設計及實現方法,完成了軟件設計,實現了高壓充電、問詢脈沖加載、時間測量及濾波等功能,并通過實驗對其性能進行了驗證。所研制的磁致伸縮位移傳感器具有測量精度高、長期穩定性好等特點,滿足了大量程、高精度、惡劣環境等測量的要求。A kind of sensor based on magnetostrictive principle is designed.The measuring principle of the magnetostrictive displacement sensor is introduced,the performance of the instrument is improved by the structural optimization design,and introduced the hardware circuit design and the Realization method,completed the software design,realized the functions of the high voltage charging,inquiries pulse loading,time measurement and filtering,and its performance is verified through the experiment.The magnetostrictive displacement sensor has the characteristics of high measuring precision.The sensor meets the requirements of large range,high precision,poor environment and so on.
標簽：
位移傳感器
上傳時間：
2022-04-06
上傳用戶：
