压下

FEM model of coupled acoustic-structure is set up, modal superpose method is used to deduce sensitivity of response acoustic pressure level to structure design variable.

基于结构-声场耦合系统有限元模型，用有限元模态叠加法推导了系统在动力载荷作用下响应声压级对结构设计变量的灵敏度。

Moreover, the hot compressive deformation behavior of the RS/PM AZ91 magnesium alloy and AZ91 alloy matrix composite were also investigated, the conclusions are drawn as follows:1. The processing parameters of the atomization-twin rolls quenching technology were optimized as follows: the diameter of the nozzle 1mm, the wheel velocity 25m/s, the pressure of atomization gas 0.3MPa and Ar gas for melt injection 0.1MPa. The RS AZ91 alloy flakes exhibited fine and uniform microstructures. When the flakes were extruded at 673K, extruded velocity of 0.1mm/min and extrusion ratio of 25:1,the magnesium alloy rods with clean surface, uniform dimension and excellent mechanical properties were obtained.2. The RS AZ91 magnesium alloy powders prepared by atomization-twin rolls quenched technology exhibited fine equiaxed grains with the grain size of 1-3μm, the phase constituent included supersaturate solid solution phaseα-Mg and miner fineβ-Mg_(17)Al_(12) phase. The as-extruded materials also exhibited equiaxed grains with the size of 5-7μm and a large number of fineβ-Al_(12)Mg_(17) and fewer AlMg_2Zn phases were detected in the alloy.

本文还研究了快速凝固/粉末冶金AZ91镁合金热压缩变形流变应力行为，快速凝固/粉末冶金法原位生成Mg_2Si增强AZ91镁基复合材料，经过系统的研究，获得如下结论：1、雾化-双辊急冷法在下列工艺参数组合下：双辊线速度25m/s；喷嘴直径1mm；熔体压射压力0.1MPa；雾化气体压力0.3MPa。，可获得宏观尺寸细小、微观组织均匀细小、综合性能优良的的快速凝固AZ91镁合金细碎箔带，快速凝固箔带在挤压温度为673K、挤压速度为0.1mm/min，挤压比为25：1时，可获得的外表光洁、尺寸均匀、组织性能优异的镁合金棒材。2、雾化-双辊急冷法制备的AZ91镁合金粉末态为细小等轴晶组织，晶粒尺寸1-3μm，组织为α-Mg过饱和固溶体和微量的细小β-Mg_(17)Al_(12)相组成；粉末挤压棒材为等轴晶组织，晶粒尺寸5-7μm，组织中含有大量细小的β-Al_(12)Mg_(17)以及AlMg_2Zn析出相，室温力学性能，抗拉强度383MPa，屈服强度275MPa，断后伸长率7.5%。

The influence of tailboard on the exit flow fields of compressor cascades with normal straight, positive and negative curved blades were investigated at zero incidence.

进行了带尾板的常规直叶片、正弯曲叶片、反弯曲叶片组成的三种矩型压气机叶栅在低速风洞上的实验研究，测量了叶栅出口流场，分析了零冲角下尾板对叶栅出口能量损失分布情况和二次流速度矢量的影响。

Axial - flow impeller compressor can be used also as a highly swirling strong swirl generator, using its strong centrifugal field and large tangential velosity component, fully utilining the high flame propagation speed in swirling flow and the strong backflow, to organize swirl combustion .

本文将轴流式叶轮压气机兼做高漩数强漩流发生器，利用其强离心力场大切向分速，充分发挥漩流下高火焰传播速度和强回流特点，组织起漩流燃烧。

The product can be used safely since the product itself is nonpoisonous and nonchemically polluted at the same time. 2.the septic tank maintainer can easily biodegrade waste materials, albumin, starch, oils, and fats. the product can eliminate 90% of the odor, decrease polluted materials, surrounding files, and improve the quality of water and environment.

当加入化粪池中以后，在压氧情况下的微生物分解能力大大提升分解排泄物中所含蛋白质淀粉油脂，可清除恶臭味达90%，减少污染泥累积延长抽水肥时间改善排放水质，减少周边的蚊蝇蟑螂等，改善环境卫生。

Marius had entered the tap-room, and had seized the barrel of powder, then he had taken advantage of the smoke, and the sort of obscure mist which filled the entrenched enclosure, to glide along the barricade as far as that cage of paving-stones where the torch was fixed.

他拔出那根火炬，把火药桶放在一叠石块上，往下一压，那桶底便立即通了，轻易到使人惊异，这一切都是在马吕斯一弯腰一起立的时间内完成的。

While Ron told Hagrid all about Charlie's work with dragons, Harry picked up a piece of paper that was lying on the table under the tea cozy.

罗恩向海格讲查理研究龙的情况时，哈利发现茶壶暖罩下压着一张小纸片，（当罗恩向海格讲述查理研究龙的情况时，哈利从茶壶暖罩下拿起了压在那儿的一张小纸片

Log-domain companding technique takes advantage of the exponential I/V characteristics of the active devices such as bipolar junction transistors, compressing the dynamic range of the input sigal and reducing internal voltage amplitudes, it can maintain large dynamic range and high operating frequency under low supply voltage , the main area of application for this technique is the implementation of continuous-time fully integrated filters with low voltage, wide dynamic range, high-frequency, and wide tenability.

对数域压扩技术利用BJT晶体管等有源器件的指数Ⅰ-Ⅴ特性，对信号作对数压缩处理，大大降低了电路内部节点电压的摆幅，能在低电源电压下保持大信号动态范围和高工作频率，该技术的主要应用是设计具有低电压、宽调谐范围、高工作频率和宽动态范围特性的连续时间全集成滤波器——对数域滤波器。

The strength criterion of rock loaded by compression stress and tensile stress can be described with linear relation of stresses.

岩石在压拉应力作用下发生的拉伸破坏可以利用应力之间的线性关系描述。

As a result, the crack propagation rates and threshold stress intensity factors for crack arrest in air and water were obtained, and revealed anisotropy.

结果表明，恒载荷下，压痕裂纹在空气和水中不断扩展， 120 h后趋于稳定，从而就可获得裂纹扩展速率和裂纹止裂的门槛应力强度因子KISCC，它们均显示各向异性。

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。