全部

• 2017-11-20 21:32發(fā)布了問答

  求解答這是什么畫，就是用彩泥在木板涂上去加工的。

  365人看過

• 2017-05-29 21:46發(fā)布了問答

  熱水采暖系統(tǒng)中的定壓排氣等問題，工程上采用什么措施來解決

  　

  380人看過

• 2014-02-10 13:37發(fā)布了問答

  2014年亳州市事業(yè)單位公告發(fā)布了嗎？什么時(shí)候考試?

  考試內(nèi)容是什么？... 考試內(nèi)容是什么？ 展開

  494人看過

• 2013-12-15 15:44發(fā)布了問答

  空投聲納浮標(biāo)

  　

  383人看過

• 2013-11-05 01:09發(fā)布了問答

  超聲換能器工作在串聯(lián)諧振頻率還是并聯(lián)諧振頻率？

  　

  779人看過

• 2013-08-19 01:19發(fā)布了問答

  怎樣測(cè)試玉的真假?

  　

  379人看過

• 2012-11-05 11:48發(fā)布了問答

  如何測(cè)試水的透明度，急急急！

  我不是測(cè)試一大片水域的，只是一杯水，比較少，要簡(jiǎn)便一點(diǎn)的方法，我只有12歲!!!!!!... 我不是測(cè)試一大片水域的，只是一杯水，比較少，要簡(jiǎn)便一點(diǎn)的方法，我只有12歲!!!!!! 展開

  445人看過

• 2010-06-08 06:43發(fā)布了問答

  什么是水采采煤法？請(qǐng)高手解釋一下（采礦專業(yè)問題）

  老師提過這個(gè)問題，可惜記不住了

  395人看過

• 2010-03-18 09:49發(fā)布了問答

  仿生學(xué)的資料

  仿生學(xué)的資料... 仿生學(xué)的資料 展開

  476人看過

• 2010-01-17 08:59發(fā)布了問答

  通信方面的英文文獻(xiàn)翻譯??！

  以下是文獻(xiàn)的一部分，愿意幫忙的高手留下郵箱，我把文件發(fā)給你，若能完成，加分：SpatialCompressiveSensingApproachForFieldDirectionalityEstimation.I.INTRODUCTIONVarietyoft... 以下是文獻(xiàn)的一部分，愿意幫忙的高手留下郵箱，我把文件發(fā)給你，若能完成，加分： Spatial Compressive Sensing Approach For Field Directionality Estimation. I. INTRODUCTION Variety of techniques for field directionality estimation were studied in literature [1]-[5]. Thus， a theoretical analysis of the relationship between the hydrophone array output and the noise field was conducted in [1]-[5]. The developed techniques were based on the array beamformer output or the crossspectral matrix between outputs of array elements [4]-[5]. The problem of a field directionality estimation in ocean， using horizontal line towed array was also addressed in literature [5]- [8]. Recently， problems of direction of arrival and field directionality estimation for moving sensors arrays have attracted renewed interest [9]-[12]. It was shown that an array motion can improve an array performance assuming temporal coherence of successive samples [10]-[11]. In [12]， the wavefield sampling method that exploits the linear relationship between the noise field and the collection of beamformer outputs over various array orientations was proposed. It was shown that the wavefield sampling (WS) method outperforms other tested methods. This algorithm was implemented via the recursive estimation method and its convergence to the unique solution was promised for a specific set of array orientations and beamformer look directions. However， a method for a proper array orientation and beamformer look direction sequence selection remains an open question. The quality of the field directionality estimation is determined by the angular resolution. The higher angular resolution is， the more accurate estimation of the far field sources， and better detection performance can be achieved. One of fundamental relations in the array signal processing is that the angular resolution is directly proportional to the number of the array elements [13]. This relation motivates the desire for longer arrays that can achieve higher resolution. Unfortunately， the requirement contradicts the implementation and installation limitations that motivate shorter arrays. Moreover， implementation of longer arrays for maneuvering platforms such as unmanned underwater vehicles (UUV) can even be impossible [14]. These contradictions motivate the quest for alternative array signal processing methods. Usually， the field directionality is modeled as a finite set of strong far-field narrow-band sources and an isotropic lowpower noise [1]. In this work， the model of the field directionality is adopted in the following way. First， the bearing angle space is uniformly sampled into a large number of discrete angles. Next， it is assumed that ether the high energy that corresponds to the far-field strong sources or the low-energy that corresponds to the isotropic noise is received at the sensor array from every of these discrete azimuth angles. 展開

  676人看過

• 2009-03-16 16:29發(fā)布了問答

  海信彩色電視機(jī)選擇亮度，【柔和】還是【個(gè)人】對(duì)眼睛刺激小

  如題。【柔和】情況下電視畫面太暗，而【個(gè)人】就會(huì)亮得多。請(qǐng)問前者是否對(duì)眼睛刺激小？有什么道理？... 如題?！救岷汀壳闆r下電視畫面太暗，而【個(gè)人】就會(huì)亮得多。請(qǐng)問前者是否對(duì)眼睛刺激小？ 有什么道理？ 展開

  798人看過