声学

Making use of test data and some instances presented in test,it could be apprvoed that partial resonant vibrations of acoustics system occurred in ultrasonic hoing.Meanwhile,it was pointed out in this paper that flexible pole-oilstone holder cou

文摘：经试验证实了超声珩磨声学系统中存在着局部共振现象，指出&挠性杆-油石座&振动子系统设计时可作为一个单独的振动体系进行考虑，为超声珩磨声学系统设计开辟了一条新的思路。

First , a syllable-based Taiwanese speech recognition system was implemented. And the effect on the recognition performance of the syllable with entering tone was carefully exiamined. Based on the linguistics knowledge, the syllable with entering tone in database was re-labeled according to the tone sandhi of Taiwanese in order to improve the recognition rate. In addition, Kullback Leibler distance between the acoustic model before and after re-labeling was examined to verify the linguistics knowledge.

在论文中首先针对台语语音特性入声调的部份深入研究，我们由confusion matrix去分析入声调对辨识系统的影响性，且根据语言学上的知识修改文字拼音资料库，使得训练出来的声学模型更为可靠，进而提升辨识率；并利用Kullback Leibler distance去观察声学模型在修改前与修改后之间的差异。

The influence of thickness of acoustic absorbing material on propagation characteristics of unsteady gaseous detonation through the right-angle tee joint bend was analyzed.

在上述的直角三通弯管中安装声学吸收材料，研究气体非稳定爆轰波的传播特性。结果表明：声学吸收材料对弯管中非稳定爆轰波传播有很大的影响。

First, it introduced the basic acoustic principle and summarized the aeroacoustic and the aero sound's source.

首先，介绍了声学的基本原理，对气流声学和气流声源作了概述。

Based on the violin, cello and double bass for the same position on the fingers rubbing strings rolling away from comparison and analysis of acoustic patterns; means single and double string rubbing rubbing means of acoustic string playing patterns and specific examples of analysis and comparison; refers to rub in the two-string Mixing strings with a single means to achieve the same sound, the string in the rubbing action on the comparison, so as to demonstrate the two-finger chord rubbing means smaller, the palm of your hand for a small, in the string rubbing speed, rubbing the string action is better than the single rate means the string rubbing , and can also increase the need for greater low-double bass string, the bit rate of rubbing

本文通过对小提琴、大提琴和低音提琴进行在同一把位上揉弦的手指滚动距离比较和声学图谱分析比较；进行单指揉弦和双指揉弦的声学图谱和具体演奏实例分析和比较；在双指揉弦与单指揉弦达到同样音响效果的情况下，在揉弦动作上的比较，以论证双指揉弦对于手指较细、手掌窄小的人来说，在揉弦速度、揉弦动作幅度上优越于单指揉弦，并且还可以根据需要更大程度上加大低音提琴低把位揉弦的幅度。

Objective To assess the role of acoustic densitometry technique in tissue characterization of normal femoral artery and atherosclerotic plaque.

目的 应用声学密度定量技术检测正常股动脉管壁及不同类型粥样斑块的声学定量参数。

Diving behavior and echolocation pulse rate of three captive porpoises in Wuhan Baiji Dolphinarium were observed continuously using both behavioral and acoustic data loggers on 23?25 November 2002. A total of 38 hr of behavioral data and 40 hr of acoustic data were recorded for each porpoise.

同时使用行为和声学微型生物跟踪记录仪，于2002 年11 月23-25日，跟踪记录了白鱀豚馆3 头江豚的行为和发声，每头江豚行为记录时间38 hr，声学记录时间40hr。

This paper investigates the acoustic features of English monophthongs produced by ethnic Korean English major students in Yanbian University.

本文运用声学分析的方法对延边大学英语专业朝鲜语主导型大学生生成的英语单元音的共振峰和音长声学特征进行实态调查与分析。

Using fluid dynamics FEM (two dimensional, three dimensional andaxisymmetric) and three dimensional acoustic FEM in meticulous analysis ofexpansion muffler structure, this paper studies the influences of each mufflercomponents' position, dimension, form and quantity on the fluid dynamic andacoustic performances;therefore the paper indicates that the end of the intruding tubeis the linchpin of the fluid dynamic performance of the whole muffler structure, thespringhead of muffler fluid dynamic performance is the smoothness of air current, themain factor which affects the acoustic attenuation value of expansion chamber muffleris the grade of saltation of the section of air conducting access, and the attenuationvalue of specific frequency can be dramatically enhanced by carefully designing thelength of expansion chamber.

本文通过流体力学有限元方法和三维声学有限元方法对扩张腔消声结构的参数化模型进行了细致的分析，研究了这种结构的各个组成部份的位置、大小、形状和数量对其流体力学与声学性能的影响，指出插入管端口是影响整个结构流体力学性能的关键，消声结构流体力学性能的根源是气流通过时的平稳程度；影响扩张腔消声量的主要因素为声波传播通路截面突变的程度，并可以通过精细的设计扩张腔轴向长度获得宽频或指定频率消声量的大幅度提高。

Based on the integration of the results of acoustic andfluid dynamic analysis, this paper points out that synthetical acoustic and fluiddynamic performance of muffler can be obtained by using square expansion chamber,by stringing together several podgy expansion chambers, by applying noise absorbingmaterial on chamber walls, by making chambers and pipers co-axial, by adding filletson the end of intruding pipes, and by making the diameter of outlet pipe a little greaterthan the diameter of the inlet pipe.

通过综合流体力学和声学有限元两方面的分析的结果，指出了采用方形扩张腔，采用多个短粗扩张腔串联，扩张腔壁面附吸声材料，使各管道同轴，在插入管端口加上圆角，并且令出口插入管管径略微大于入口插入管管径可以使消声结构获得最佳的声学和流体力学综合性能。

Cynanchum Lingtai apricot production in the average weight 65 grams, the brightly-colored fruit, juicy rich, sweet-sour taste, sweet from the nucleolus, when the late Qing Dynasty famous Shaanxi, Gansu provinces, the Qing imperial court Tongzhi tribute for years.

灵台生产的牛心杏平均单果重65克，果实色泽鲜艳，汁多味浓，甜酸适口，离核仁甜，清末时就驰名陕、甘两省，清同治年间曾为朝廷贡品。

Chenopodium album,Solanum nigrum, and Amaranthus retroflexus were very susceptible to the herbicides. Polygonum persicaria and Abutilon theophrasti were relatively less susceptible to the herbicides, and Lycopersicon esculentum was not susceptible to it. The relationship between reduction rates of weed biomass and PPM values of weed leaves 2,4, and 6 days after treatment was established.

供试的6种杂草对该混剂的敏感性存在显著差异：红心藜Chenopodium album、龙葵Solanum nigrum和反枝苋Amaranthus retroflexus对该混剂最敏感，ED90值分别为47.65、71.67和29.17g/hm2；春蓼Polygonum persicaria和苘麻Abutilon theophrasti敏感，ED90值分别为96.91、114.20g/hm2；而番茄不敏感。