压下的

The principle is using thefast breakover of avalanche transistor drive the electron tube. The full time of 4200Vvoltage is about 20ns. The circuit can normally work under 100kHz frequencies.Design an extra fast Q-switch circuit by series arrangement of avalanche transistor.

本论文主要做了以下几方面工作：1、推导了重复率激光基本参数(脉冲能量、脉冲宽度和峰值功率)与周期的关系，并且分析了重复率激光系统运转的稳定性。2、设计了雪崩管-电子管退压电路，由雪崩管驱动电子管开关，4200V高压退压沿20ns左右，能够在100kHz频率下工作。

Using the first order shear deformation theory for plate and mechanical-electro coupled variational equation, the two dimensional dynamic finite element formulation containing the effect of pressure in the cavity was derived.

数值分析了在不同的结构和声腔共振频率下主动控制效果，结果表明通过合适地布置压电片，能够很好地控制腔体的声压与位移。

The average depth of erosion on gritstone for cavitation water jets is 2 times as much as common water jets, and its mass erosion is 7 times as much as common water jets, and its diameter of erosion is 2.3 times as much as common water jets.

对于含有空泡的磨料射流，围压增加空化噪音减少，泵压增加空化噪音增加；有效靶距直径比增加，对花岗岩的冲蚀深度与冲蚀质量存在一最优有效靶距直径比；在最佳冲蚀时间下，较纯水空化射流工作效率提高2倍。

The damage represents complex mechanism. In this research based on T300/HT3 laminate structure, fatigue life is predicted phenomenologically, dealing mainly with in-plane stresses without accounting for out-of-plane failures such as craze. Fatigue modulus, based on damage mechanics, is used as a physical parameter which helps to describe the basic fatigue behaviors of unidirectional laminates and obtain expressions for cumulative damages defined by strains and stress. Based on some typical fatigue test data for unidirectional composite laminates, residual modulus sequence is found out.

本文以T300/HT3复合材料层压结构为研究对象，从唯象的观点出发，以损伤力学为基础构造损伤函数，考虑了剩余刚度和应变比率对复合材料的疲劳性能的影响，以这些变化着的机械性能作为损伤变量，建立了复合材料的疲劳损伤模型，基于层压板拉—拉疲劳试验数据，拟合出损伤模型中的参数，从而得到层压板拉—拉疲劳损伤变化规律，并建立损伤变量与内部损伤及疲劳寿命的联系，从而预测常幅应力作用下疲劳寿命。

Based on the project of high-embankment widening of highway, the water content and degree of compaction of foundation soil, filling and improved soil by lime were determined by means of indoor physicomechanical test. The centrifugal modeling tests were used to simulate increasing degree of compaction and improve soil by lime for coordinating deformation between new and old high-embankment widening.

针对高速公路拓宽工程高填方路段新老路堤拼接问题，通过室内物理力学试验确定地基土、素土填料及其石灰改性土在拼接路堤填筑时的含水量和压实度控制参数；利用离心模型试验手段，进行提高填料压实度和石灰改性措施下拼接路堤协调变形试验研究。

It is helpful to removing the particles of blocking flow channel, reducing formation damage and improving underbalance perforation.Perforating-well testing operation is performed at a pressure higher than the minimum underbalance.

在大于最小测试压差下进行射孔测试联合作业，有利于堵塞地层的细小微粒返排出来，减少地层损害，提高负压射孔效果。

Such as: calibrating the laser system, calibrating the measurement region and focusing the CCD camera for the diffuser passage with complex shape, selecting the best incidence angle for the laser sheet,, setting the time parameter including the time between pulses and the time between records, designing the laser system, and selecting water fog with 1～5μm diameter as seedings for PIV measurement after comparing several particles. All of the work is useful to accumulate the PIV measurement experience in turbomachinery. 2. Experimental research of the unsteady flow in diffusers The instantaneous velocity fields within the vaneless and vaned diffuser were measured by using PIV technique.

本文在国内首次进行PIV测量系统对离心风机扩压器内部非定常流动的测量，为此，作者作了必要的实验前期工作：双谐振激光器工作特性的标定；针对扩压器复杂的流道形状，解决了片光源照射区域位置的标定和CCD相机的聚焦等问题；为复杂流道形状的扩压器内部流动的PIV测量选择了最佳片光源入射角度；选择了合适的PIV测量时间参数；为实现非定常内流的PIV测量设计了PIV系统的光路布置；根据非接触测量示踪粒子的选取原则，对几种示踪粒子进行了筛选，最终1～5μm的水雾粒子在本文实验条件下获得最佳效果。

The leaching residue was cyanided to recover gold and silver in the presence of rich oxygen.

在较低的压力下(氧压0.4-0.6MPa)对所得精矿进行氧压氨浸，使硫转化为硫酸铵，铜进入溶液，金银留在浸渣中。

The study we have performed demonstrated that the main roof first broke with asymmetry character; gully mining-induced slope was divided into multilateral blocks by surface advance cracks. Furthermore, multilateral blocks rotated and subsided by the function of extrusion and friction between the broken rock block above the goaf and the rock mass advance the coalface.

冲沟坡体下开采时，基本顶初次破断具有不对称性；冲沟采动坡体被地表超前裂隙切割成多边块状，并在两侧坡体的夹持摩擦作用下缓慢回转下沉；相同地质条件下，坡角越大，采动坡体对工作面矿压影响越大。

The shoe must be under the second stage pressure for a minimum of 12 seconds,under the correct pressure

在正确的压力下，压底时间应从第二个压底过程开始算起至少12秒

This one mode pays close attention to network credence foundation of the businessman very much.

这一模式非常关注商人的网络信用基础。

Cell morphology of bacterial ghost of Pasteurella multocida was observed by scanning electron microscopy and inactivation ratio was estimated by CFU analysi.

扫描电镜观察多杀性巴氏杆菌细菌幽灵和菌落形成单位评价遗传灭活率。