声波

Active noise control is achieved by introducing a canceling "anti-noise"wave of equal amplitude and opposite phase using a secondary source.

主动消声是利用声波之间的相消性干涉原理，使声场局部区域声能相互抵消，从而达到降低噪声的目的。

Paraxial approximation absorption boundary condition based on acoustic wave equation can obtain better absorption results by increasing paraxial approximation order of Taylor series. However, this kind of operation will increase the complexity of difference computation, and result in instability of computation process.

基于声波波动方程的旁轴近似吸收边界条件可以通过提高泰勒级数展开的旁轴近似阶数获得更好的吸收效果，但这样不仅增加了差分计算的复杂性，同时还导致计算过程不稳定。

Based on this, a new WENO difference scheme which based on Dispersion-Relation-Preserving relation is developed, and representative test cases with this scheme for computational aeroacoustics problems has been implemented and compared in order to test capability of wave capturing; In addition, WENO schemes generally do not converge at high order in the presence of contact discontinuity of Euler equations, so a conservative front tracking technique coupling WENO schemes and Level Set method to simulate the translating density profile is presented here, and numerical simulation with this technique for representative test case has been implemented and results show the desired accuracy.

本文研究了高阶精度加权基本无振荡格式及其在双曲守恒律方程中的应用，在此基础上作了两个方面的工作：一是针对高频声波问题构造出一种基于保色散关系的WENO有限差分格式，并对计算气动声学问题的代表性算例进行了大量数值实验，比较了该格式捕捉波数的能力；另外，针对高阶WENO格式在处理Euler方程的接触间断时精度有所降低的问题，研究了利用界面追踪技术Level Set方法和高阶激波捕捉WENO格式相结合的一种守恒追踪方法，并且给出有代表性的密度滑移面问题的算例，得到一致高阶精度的数值模拟结果。

Rock mechanics ; orthotropy ; experimental method ; true triaxiality ; cross-multipole array acoustilog

岩石力学；各向异性；实验方法；真三轴；偶极声波测井

This paper has presented the types and distribution characteristic of the Quaternary glacial deposits on the west side of the Yulong Mountains, which was an important task for the selection and optimization of the Yunnan-Tibet railway line in Northwest Yunnan. Based on lab test of physics and mechanics, the results of engineering properties of moraine/outwash rocks, including the cement composition and their cementation, stability in water, mechanical property, and sound spreading velocity, etc., have been reported, which can not only enrich the research contents of rock mechanics, but also have important practical value for railway construction and water power development in mountain regions.

结合滇藏铁路滇西北段线路比选和优化工作，对云南玉龙雪山西麓第四纪冰川堆积物的类型和分布特征进行了详细的野外调查；在室内物理力学试验的基础上，着重研究了冰碛砾岩的胶结物成分与胶结作用、水稳性、力学性质、声波速度等方面的特性，这不仅可以丰富现代岩石力学的研究内容，而且对本区铁路工程建设和水力资源的开发具有重要的实际价值。

Fluorescent or dye penetrating substances may be used for liquid penetrant inspection.

超音波测试利用自然的电子被计时的波浪和声波一样，但一个高音调或频率。

Versatile cleaner is perfect for any number of small household items that require special care.

先进的声波技术使用普通的自来水，轻柔彻底消除珠宝表面的污物和锈蚀。

Hearing begins when sound waves that travel through the air reach the outer ear, or pinna, which is the part of the ear you can see.

听证会开始时，声波的旅行通过空气进入外耳，或耳廓，这是一部分的耳朵可以看到。

Hearing begins when sound waves that travel through the air reach the outer ear, or pinna, which is the part of the ear that's visible.

听证会开始时，声波的旅行通过空气进入外耳，或耳廓，这是一部分的耳朵是可见的。

It is important to recall that a sound wave in a nonhomogeneously deformed material cannot be a plane wave.

重要的是要记得，非均匀变形材料中的声波不可能是平面波。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。