low frequency group 中文意思是什麼
low frequency group
解釋
低頻率組-
Due to the short distance among the planes which fly in a group, the conventional low resolution radar can not distinguish them in both distance and azimuth ? if we use the technology of isar to resolve the difference among doppler frequency of the targets and obtain a fine resolution cross - cross image, we may separate them, but a long time of coherent processing is needed <, for the formation targets, it can be approximately divided to rigid body and nonrigid body, so for the formation targets, that can be regarded as rigid which has a relative position and an identical movement, can be approximately considered as a large target, and be compensated by translational phase with the rule of minimum entropy, but for the most those cannot accord with the approximation of rigid, being the doppler - frequency of the aim is linear changed, by the relax method with short data, increases the resolving performance of multiple target to the aim in the frequency domain, since cross - range resolution is based on the accumulative time, so it is greatly improve the resolution to formation targets by the instant cross - range image which produced by radon - wigner transformation
低分辨isan成像及干涉技術應用研究一因此直接無法分辨編隊目標的架數，我們借鑒isar的技術，通過較長時間的相干積累，在多普勒頻域上對目標進行分辨。而對于編隊目標，可分為近似剛性的多目標和非剛性的多目標，所以對于可以近似為剛體的編隊目標相對位置固定，運動方式一致，可以近似看作一個大目標，採用最小墑準則對平動相位的進行補償，但是大多數並不滿足剛體近似的編隊目標，由於目標在相干積累時間的多普勒頻率近似呈線性變化，通過對較短數據利用relax的時頻分析方法，提高了頻率域上目標分辨的性能。由於橫向解析度取塊于橫向積累時間，所以利用radnwigner變換得到瞬時的一維橫向距離像大大提高了對編隊目標的分辨，對模擬和實測數據的大量分析結果表明此方法的有效性和可行。 -
In this paper, difficulties such as the design of hts microwave passive component, the lithography technology, encapsulation and testing at low temperature etc. are solved. a hts delayline with center frequency at 4ghz, bandwidth of 4ghz is manufactured and tested. it ’ s group delay is larger than 10 ns
本文在解決高溫超導微波無源器件的設計、光刻工藝、密封封裝和低溫測量等難點的同時，對一個f _ 0 （中心頻率）為4ghz ，帶寬4ghz的高溫超導延遲線進行加工、封裝、測量，群時延大於10ns 。 -
In the fifth chapter, a new fully differential operational amplifier with voltage and current - mode negative feedback has been proposed, which can stabilize its quiescent operation point, using the characteristic of mos transistors which operate in the triode region acting as active variable resistor, a fully differential fourth - order chebyshev low - pass filter with tunable frequency and bessel low - pass filter with accurate group delay based on r - mosfet - c and operational amplifier has been designed
第五章：提出了一種新的既具有電壓共模負反饋又同時具有電流共模負反饋的全差分運算放大器電路，能較好地穩定電路的靜態工作點，並應用mos管工作在線性區可作有源可變電阻用的特性設計得到了截止頻率可連續調節的高性能r - mosfet - c 、運放結構切比雪夫（ chebyshev ）和精確群時延值貝塞爾（ bessel ）低通濾波器。 -
Results the frequency of discomfort, low blood pressure and arrhythmia in the treatment group is lower than that in control group ( p < 0. 01 ) but the density of kalemia in serum does not obvious change
結果高鉀透析組患者在不適癥狀、低血壓、心律失常發生率等方面均顯著低於對照組（ p < 0 . 01 ） ，而透析后血清鉀濃度無明顯改變。
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