回声

This thesis focuses on two main issues of acoustic echo cancellation, namely the adaptation algorithm and the control of adaptation in double talk situation presents all the theory backgrounds.

本文重点的两个主题是声学回声消除技术，也就是在双重谈话的情况下，回声过滤器适应算法和适应控制。

Based on the study of adaptive echo cancellation techniques, an echo cancellation scheme without the need for double talk detection is presented.

首次提出了无双端对讲检测回声抵消系统的概念和框架，突破了传统自适应回声抵消技术必须进行双端对讲检测的限制。

The penile mass was located just proximal to the glans penis and measured 3 x 4 x 3 cm. Sonography revealed the mass to be located in the midline, displacing both corpora cavernosa laterally. It was well encapsulated, showing a uniform echo texture, isoechoic to the corpus cavernosum, with no involvement of Buck's fascia.

阴茎的肿块就位于龟头的近端，大小为3×4×3cm，超声显示肿块位于中线处，将两侧海绵体挤向侧方，其包膜清晰，回声均质，与海绵体呈等回声，未累及Buck筋膜。

Thus, the neurons with sharp frequency tuning and high Q 10 -dB values showed that there was certain relationship between echolocation call and frequency tuning of IC neurons in the leaf-nosed bats.

结果表明，大蹄蝠回声定位信号与下丘神经元频率调谐存在相关性，表现为最佳频率在回声定位信号主频附近的神经元频率调谐曲线的Q10-dB值较大，具有很强的频率分析能力。

The results showed that the echolocation calls of the leaf-nosed bats were constant frequency-frequency modulation signals with 2-3 harmonics and the second one among these three harmonics was its dominant frequency. The constant frequency components of three harmonics (Mean±SD, n=18 ) were 33.3±0.2 kHz, 66.5±0.3 kHz, and 99.4±0.5 kHz, respectively. In examined FTCs of 72 IC neurons, their Q 10 -dB values ranged from 0.5 to 95.4 (9.2±14.6) and the neurons whose best frequency around the dominant frequency had sharp frequency tuning.

结果发现，大蹄蝠回声定位叫声为恒频-调频(constant frequency-frequency modulated，CF-FM)信号，一般含有2~3个谐波，第二谐波为其主频，CF成分频率(Mean±SD，n=18)依次为：(33.3±0.2)、(66.5±0.3)、(99.4±0.5)kHz；电生理实验共获得72个神经元的频率调谐曲线，Q10-dB值的范围是0.5~95.4(9.2±14.6， n=72)，最佳频率(best frequency，BF)在回声定位主频附近的神经元具有尖锐的频率调谐特性。

After thyroid artery embolization, the size and vascularity of thyroids werereduced while the thyroid echo was increased. The thyroid arteries were narrowedwithout any blood flow at the embolized site.

结果：术前腺体增大为弥漫性、均质或是非均质低回声，部分有结节，腺体内血管多而粗；术后腺体缩小，回声增强，血管变细而小。

Results In the 24 cases, B - Flow displayed low level echo or medium echo blocked the lumen of the vessels or pardy, and clearly showed the shape and size of thrombus and relationships between the thrombus and the vessels wall without overflowing artifact.

结果24例病例中，B—Flow显示在血管内见低回声或中等回声，充填或部分充填血管腔，并能清晰地显示血栓形态、大小、血栓与管壁的关系，无血流外溢伪像。

Results As compared with the group without plaque ,The mean wall shear stress in group with plaque was lower.

结果 无斑块组和有斑块组之间、高回声和低回声斑块组之间血流壁切应力均有显著性差异（P〈0.01）。

Results Smooth hypoechogenicity, size and abundant blood supply of hyperparathyroidism were observed by color Doppler ultrasound before treatment.

结果 增生的甲状旁腺在治疗前回声呈均匀一致的低回声，腺体内血供丰富。

This method is different from the traditional methods which need to detect the double-talk cases in solving the echo problem during the double-talk periods.

该算法不同于现有的回声抵消算法，它在进行回声抵消的过程中，不需要进行双端会话检测。

It has been put forward that there exists single Ball point and double Ball points on the symmetrical connecting-rod curves of equilateral mechanisms.

从鲍尔点的形成原理出发，分析对称连杆曲线上鲍尔点的产生条件，提出等边机构的对称连杆曲线上有单鲍尔点和双鲍尔点。

The factory affiliated to the Group primarily manufactures multiple-purpose pincers, baking kits, knives, scissors, kitchenware, gardening tools and beauty care kits as well as other hardware tools, the annual production value of which reaches US$ 30 million dollars.

集团所属工厂主要生产多用钳、烤具、刀具、剪刀、厨具、花园工具、美容套等五金产品，年生产总值3000万美元，产品价廉物美、选料上乘、质量保证，深受国内外客户的青睐