頻數多角形 的英文怎麼說
中文拼音 [bīnshǔduōjiǎoxíng]
頻數多角形
英文
polygon frequency-
In the terms of interpolation, the image reconstructed from nearest interpolation or linear interpolation has good edge but serious noise ; reconstruction from 4 * 4cubic interpolation or three b - spline or three - order lagrange interpolations has better local character. 2 x 2cubic interpolations which has both better edge and local character is the ideal interpolation, the following is the basic principle during reconstruction : ( 1 ) the more width of interpolation, the more number of summation and the more order of interpolation polynomial, the higher of density resolution ; ( 2 ) the more of interpolation polynomial and width of interpolation, the more of reconstruction time simultaneously, aimed at eliminating the effects of noise contained in projection data, in this paper, author analysis cause and effects of common artifacts. importantly, discusses convolution back - projection reconstruction algorithm with a shift axis of rotation has been derived for correcting images that acquired with a divergence axis of rotation using the fan beam geometry with an angle - equaled detector
在ct圖像重建時，選擇有限帶寬窗有較好的空間解析度，三角形窗有較好的密度解析度，選擇餘弦窗則使得空間解析度與密度解析度的折衷；從窗函數的頻譜角度來講，可以用於圖像重建的一個良好的卷積窗函數應該具備以下條件： （ ? ）小的3db帶寬b ，即最小的主瓣寬度； （ ? ）最小的旁瓣最大峰值a ； （ ? ）最大的旁瓣峰值衰減速度d ；就內插函數而言，臨近點內插與線性內插重建圖像噪聲大，但有較好的邊緣與細節； 4 4三次內插、三次b -樣條與四次拉格朗日多項式內插圖像平滑，局部特性較好。Firstly a microstrip - fed microstrip patch antenna has been emulated and validated. on the base of this, the multi - band property of sierpinski equilateral triangle and squareness microstrip fractal patch antennas are carefully studied, and the effect of antenna ' s property by the permittivity, the size of patch, the order of the fractal and the decrease of fractal patches is depicted ; secondly on the base of analysis and comparison of performance of microstrip - fed semicircle and rectangle double - band microstrip patch antennas, warranty of dimension curtailment is offered ; finally expansion of band of those antennas above is discussed
在此基礎上，著重分析了微帶線耦合饋電的sierpinski等邊三角形微帶分形貼片天線以及sierpinski方形微帶分形貼片天線的多頻特性，給出了介質參數、貼片尺寸、分形的階數以及減少分形貼片數對微帶線耦合饋電的sierpinki等邊三角和sierpinski方形微帶分形貼片天線特性的影響；其次基於微帶線耦合饋電的半圓雙頻微帶貼片天線和矩形雙頻微帶貼片天線的性能分析和比較，提供了尺寸縮減的依據；最後對以上天線的頻帶擴展進行了探論。
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