In ultrasonic inspection of butt weld s, interfering echoes, such as corner echo, hill-shaped echo, etc.

在對(duì)接焊縫超聲波探傷中，熒屏上常會(huì)出現(xiàn)一些影響缺陷判別的干擾回波www.nlvnja.com，如焊角回波羞羞呦呦视频在线免费播放、"山形回波"等。

Especially, the technology of Automatic Gain Control and signal processing are studied which are key factors working on the performance of the receiver. Based on analyzing the theory of automatic Gain Control, operational amplifiers 0P37 and logarithmic D/Aconverter AD7111A are used to design variable gain amplifiers which can be controlled numerally, A/D convector LTC1405 is Used to test the echo, Complex Programmable Logic device is used for controller, and an arithmetic is designed for automatic Gain Control which is simulated and analyzed in order to test its feasibility.

本文在分析自動(dòng)增益控制AGC原理的基礎(chǔ)上久久久久亚洲AV无码专区电影，采用集成運(yùn)放OP37和數(shù)控增益衰減器AD7111A設(shè)計(jì)可數(shù)字控制的可變?cè)鲆孢\(yùn)放模塊欧美喷水网站一级a片；采用高速A／D轉(zhuǎn)換器LTC1405作為回波信號(hào)檢測(cè)模塊；采用復(fù)雜可編程邏輯器件CPLD作為核心控制模塊www,高潮,c0m，構(gòu)成數(shù)字自動(dòng)增益控制電路欧美黄色插插，并設(shè)計(jì)粗調(diào)和細(xì)調(diào)步進(jìn)控制相結(jié)合的算法，對(duì)回波信號(hào)的增益進(jìn)行精確而快速的調(diào)節(jié)控制天天舔，使回波信號(hào)振幅快速穩(wěn)定在設(shè)計(jì)指標(biāo)范圍內(nèi)人妻AV无码系列专区移动可看，利于接收機(jī)后續(xù)信號(hào)處理電路對(duì)回波信號(hào)作進(jìn)一步的處理18禁黄网站禁片无遮挡。

In the precision detection of a millimeter wave, the encounter of the detector and the objects can not be forecasted totally because of a lot of noise and disturbance existing in the complex battlefield, it will cause fantasticality and distortion of the echo retaked by the detector, and the stably of the echo become bad, as a result, it will reflect the result of the detection, so it is necessary to filter the echo retaked by detector.

在彈載毫米波精確探測(cè)系統(tǒng)中，由于復(fù)雜多變的戰(zhàn)場(chǎng)環(huán)境中存在大量的干擾及噪聲在线资源av网站，探測(cè)器與目標(biāo)的交會(huì)姿態(tài)不能完全預(yù)測(cè)永久黄网站色视频免费大全91，造成探測(cè)器獲取目標(biāo)回波產(chǎn)生奇異和變形，回波特征的穩(wěn)定性變差日韩啪啪小视频，從而影響了目標(biāo)的探測(cè)和識(shí)別欧美成年性开放视频在线播放，因此對(duì)探測(cè)器的回波進(jìn)行有效的濾波處理是十分必要的。

In accordance with the generating principle of line echo and after analyzing main echo cancellation algorithms, and after in-depth study on the core algorithms of all the module of adaptive echo canceller, in particular, adaptive filtering algorithm and double talk detection algorithm, considering with complexities and capabilities of all the candidates, this paper chooses NLMS algorithm to implement echo canceller.

首先国产在线视欧美亚综合，對(duì)回波產(chǎn)生原理和目前幾種常用回波消除算法進(jìn)行了分析，在研究自適應(yīng)回波消除器的各個(gè)模塊国内免费合计自拍偷拍小视频，特別是深入分析各種自適應(yīng)濾波算法和雙講檢測(cè)算法国产农村老熟女国产老熟女，綜合考慮各種算法的運(yùn)算復(fù)雜度和性能的情況下，這里采用NLMS算法實(shí)現(xiàn)白適應(yīng)回波消除器深夜在线观看网址。

D False images caused by side lobe, multiple reflection images, and secondary reflection images

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The result shows that the severe convective storm was based on the favourable large scale weather background,complex orography triggered the origin of single cell which was developed to severe storm made up of multiple cells causing hail and severe wind,characteristics of radar echo was evident.

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In this chapter, three kinds of target recognition methods are performed, which are:①Target recognition method based on the description of polarization parameter plane. The echo polarization states of target are projected onto the polarization state plane described by the ellipticity ε and the tilt angle τ of the polarization ellipse, the change of parameter following ferquency becomes the chart. According to the changing trait of the chart, the multidimensional polarization feature space of target has been contructed. Furthermore, a series of polarization feature parameters used in designing the structure of target recognition device are extracted, and they are insensible to the posture of target.②Target recognition method based on the description of Poincare polarization sphere. The echo polarization states of target expressed by Stokes vector are projected onto the Poincare polarization sphere. The conception of polarization ferquency stability, which is used in describing the dynamic distribution characteristics of the target echo polarization states on Poincare polarization sphere, has been defined. A group of polarization feature parameters used in designing the structure of target recognition device are extracted, and they are insensible to the posture of target.③Target recognition method based on the description of frequency sensitivity. In accordance with the conception of the polarization state distance defined on Poincare polarization sphere, the frequency sensibility of the physical structure property of target has been investigated, the frequency distribution feature curves in PSD domain are obtained, and targets'features are extracted by means of the curve-fitting method with Least Square Criterion.

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These appearances including V-style rabbet, advent of bounded weak echo region, stronger wind vertical shear and phenomenon of airflow convergence in radar precipitation echoes were all typical characteristics of strong convective weather echoes.

雷達(dá)回波上的"V"形槽口www.国产盗摄.com、有界弱回波的出現(xiàn)、較強(qiáng)的垂直風(fēng)切變以及氣流輻合現(xiàn)象国产无套视频在线观看AA在线，均為強(qiáng)對(duì)流天氣回波的典型特征五月婷婷超碰在线。

Careful analysis on NBE can facilitate nowcasting of severe weather events and further understanding of their evolution. After detailed study on three cases concerning with NBE, it is concluded:(1) NBE triggered by fast moving echo in upstream is an important indication of disastrous wind;(2) NBE can develop into severe storm under proper conditions. There are often two stages during this kind of growing: the first is developing of initial echo, the second is snap growing of echo core;(3) Doppler radar reflects outflow of downburst as a nearly ringed NBE. Inside look on downburst can be obtained combining NBE with other data.

文章結(jié)合發(fā)生在上海的3次強(qiáng)對(duì)流天氣個(gè)例，詳細(xì)分析了弱窄帶回波在分析和預(yù)報(bào)強(qiáng)對(duì)流天氣中的作用咬美女奶子舔她的逼视频，得出以下結(jié)論：（1）上游移動(dòng)強(qiáng)回波的出流邊界導(dǎo)致的弱窄帶回波是大風(fēng)預(yù)警的重要判斷參考国产高清一级做a爱在线观看；（2）在合適的層結(jié)狀態(tài)和抬升條件下，弱窄帶回波會(huì)強(qiáng)烈發(fā)展18岁观看网站，并導(dǎo)致局地雷雨大風(fēng)国产精品永久免费高清，這類強(qiáng)對(duì)流天氣的發(fā)展有兩個(gè)比較重要的階段：弱窄帶回波上初始回波的發(fā)展和回波躍增；（3）下?lián)舯┝髟斐傻牡孛娉隽髟诶走_(dá)回波上表現(xiàn)為近似圓弧的弱窄帶回波性爱黄色片无码，這種弱窄帶回波與其他雷達(dá)觀測(cè)特征以及地面觀測(cè)相結(jié)合免费无码中文A级毛片，有助于對(duì)產(chǎn)生下?lián)舯┝鞯膶?duì)流云的發(fā)生發(fā)展過程進(jìn)行細(xì)致分析。

However, the latter more complicated, contrasted between radar data and routine observatory data. It can be seen that the classification of the storm rainfall echo according to 850hPa effective system is more ideal, the storm rainfall echo is classified into storm rainfall of trough and storm rainfall of shear line, while storm rainfall of shear line includes storm rainfall of warm shear line and storm rainfall of cold shear line, and their radar echo features are investigated. It is shown that different storm rainfall style is distinct clearly on the echo structure and feature.

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