退下

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。

The main research contents and results are given as follows:(1) Principles and characteristics of different types of polarization controllers are analyzed, the compare of the difference of these polarization controllers are discussed based on them, drawn a conclusion that the polarization controller which based on squeezing fiber and has variable delay quantity are suitable for high speed optical communication system.(2) The reset principle of the typical four channel polarization controller which is based on squeezing fiber is analyzed, and the design of its concrete reset scheme is given based on them. The reset process and the corresponding operation list are given in detail.(3) The systematical experiment is made when the typical four channel polarization controller is put into the PMD compensator. The experiment result showed that the channel which needs reset can efficiently return to the mean place, and the effect of reset was good, it didn't cause any badness infection on PMD compensation.(4) A new type optical signal time-domain depolarizer is given, and a new PMD compensate method is given based on it.

由此得出延迟量可变型光纤挤压型偏振控制器适用于高速光通信系统的结论；(2)具体分析了典型的四通道光纤挤压型偏振控制器的复位原理，并在此基础上对其进行了具体复位方案的设计，给出了各种情况下的详细复位流程和相应的复位操作列表；(3)将四通道光纤挤压型偏振控制器应用于偏振模色散补偿器中进行系统实验，实验结果表明，需要复位的通道能有效地回到中间值，复位效果良好，且复位未对PMD补偿产生不良影响；(4)设计了一种新型的光信号时域退偏器，并基于该退偏器提出了一种新型的偏振模色散补偿方法。

Thus in this thesis, we will made a detailed introduction of our method--perturbation based on unitary transformation, and apply it to several models to investigate the Non-Markovian decoherence and disentanglement dynamics of dissipation two-state system.

本文中，我们介绍一种新的解析方法-基于幺正变换下的微扰理论，并且把此理论应用到具体的实验模型中，推导了耗散二能级系统非马尔可夫退相干和退纠缠动力学。

Among these methods, it is surprising that few if any fundamental treatments of decoherence exist that include the dynamics of disentanglement with better than the Markovian approximation or phenomenological tradition.

所以研究环境对量子系统的影响，以便减缓环境对其包围下的量子系统的耗散、退相干、退纠缠等负面作用，就成为当今非常重要的课题。

The magnetic stripe of the drum demagnetization on a drum on latent image to demagnetization treated so that it does not take magnetic, in preparation for the next page of the business card printing and membership card production

磁鼓退磁磁条（对磁鼓上的磁化潜影进行退磁处理，使之不带磁性，以准备下一页的制卡和会员卡制作

The concentration and inventory of SOC and the decreasing magnitude of SOC with the soil profile depth under all the studied reafforestation patterns were lower than those under shrubbery land conditions, which received the least impact of land use change.

9与农耕地相比，退耕还林实施5年后，大部分退耕模式下0～30 cm的土层SOC含量和碳密度都有不同程度的提高，但在整个0～60cm土层，SOC含量和碳密度没有显著变化(个别模式甚至还有一定程度的下降)。

The main contributions are as follows:(1) The decoherence suppression of N level Markovian systems is investigatedby the optimal control in the coherence vector representation. The N level Markoviansystem can be described by the master equation, and possesses a standard bilinear formin the coherence vector representation.

本论文利用密度矩阵相干向量表示研究了退相干效应的抑制和相应的纠缠控制问题，论文主要工作包括：(1)在密度矩阵相干向量表示下，利用最优控制研究N能级Markov系统的退相干抑制问题。N能级Markov系统可以用主方程模型描述，在相干向量表示下具有标准的双线性形式。

Results Extensive and diffuse synovial hyperplasia can be seen in patients with RA;synovial pannus formation can be seen in 25 cases.

结果RA组病人均可见广泛、弥漫的滑膜增生，其中25例病人可见滑膜血管翳形成，而OA组仅7例病人可见轻度滑膜增厚，未见滑膜血管翳形成者(X2=55.78P.005)；RA组关节软骨及软骨下骨改变较严重且弥漫，而OA组软骨退变则较局限，且以关节摩擦大的部位受损为著，其软骨下骨改变较为局限，常常见于IV软骨退变；关节腔积液、半月板及韧带改变，在OA组与RA组之间无差异。

Taking household\'s land use preference as classification rule, household agent types were divided though classification tree. Different choosing process of current production strategies and theirs probabilities after expiration of GFGP chosen by various types of household agents\' were put forward by experience-weighted attraction model based on bounded -rational approach. Finally, forecasting the results of households\' recultivation behaviour after the expiration of GFGP by scenario analysis method. The results show that relative policies are useful to rectify deviation of households\' bounded-rational behaviours and reinforce outcomes of GFGP.

以农户家庭户主的土地利用选择偏好作为分类依据，采用分类树方法对农户智能体类型进行划分；基于有限理性决策理论，引用经历—权重吸引模型，对农户智能体的目前生产策略决策过程和退耕还林政策期满后农户对不同生产策略的选择概率进行了分析；最后，在ERDAS环境下对退耕还林政策期满后农户的复垦行为进行了情景分析，认为政府制定并实施的相关政策措施对于纠正农户的有限理性行为偏差，维持和巩固退耕还林政策成果具有重要作用。

Based on the simulation of 3D unsteady muzzle brake flow field, computed the force given to the barrel while the powder flow through the muzzle brake, calculated the max backlash velocity, and lastly got the efficiency of muzzle brake.

该方法以带炮口制退器三维非定常流场的数值模拟为基础，通过计算火药气体流经制退器时火炮身管的受力，计算出身管在火药气体作用下的最大自由后坐速度，进而根据制退器效率的定义得到炮口制退器的效率。

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。