Wu-King 加载偶极天线的FDTD分析

 用时域有限差分法分析了高斯脉冲激励的Wu-King加载偶极天线的特性。给出了天线周围空间瞬态场的变化情况及天线上的电流波形，这种形象化的结果为加载脉冲辐射天线的设计和改进提供了直观的物理依据。通过时域远近场变换，得到了天线脉冲辐射远场。计算并给出了描述脉冲辐射器性能的时域参数：保真度和能量方向图。     

Single-frequency 1.25 W monolithic lasers at 1123 nm

Experimental investigation ofd Nd:YAG monolithic nonplanar ring lasers operated at 1123 nm wavelength is presented. Stable single-frequency 1123 nm laser output has been obtained with successful suppression of the strong 1064 nm radiation. Single-frequency output power of 1.25 W is demonstrated with a pump power of 3.98 W at 808 nm, which gives a slope efficiency of 39%. The laser frequency tuning range is over 3 GHz, and the average tuning rate with temperature is -2.6 GHz/ degrees C. A strong iodine absorption line can be covered within the laser frequency tuning range.     

Multiphonon Bundle Emission in a Strong-Coupling Cavity Optomechanical System

Nonclassical effects in mesoscopic systems have attracted much attention recently. In this paper, it is shown that multiphonon bundle emission can be observed in a strong-coupling cavity optomechanical system. Theoretical analysis shows that when the driving field is adjusted to nth-order sideband excitation, the coupling between the cavity mode and the vibrational mode leads to super-Rabi oscillations, and finally results in an n-phonon bundles emission. Based on the current technology, this process can work in a wide range of parameters. Numerical simulation confirms the validity of the derivation. It is thought that this physical mechanism broadens the applications of cavity optomechanical system in realm of quantum phononics, such as in quantum metrology and phonon laser.     

A model for dependent default with hyperbolic attenuation effect and valuation of credit default swap

A hyperbolic function is introduced to reflect the attenuation effect of one firm's default to its partner.If two firms are competitors(copartners),the default inten- sity of one firm will decrease(increase)abruptly when the other firm defaults.As time goes on,the impact will decrease gradually until extinct.In this model,the joint distri- bution and marginal distributions of default times are derived by employing the change of measure,and the fair swap premium of a credit default swap(CDS)can be valued.     

结构综合的曲线寻优近似解析方法

本文首次在结构优化领域应用曲线寻优近似解析方法，数值实验表明本文方法的效率较高     

转镜式高速相机扫描速度及其不均匀性测量

介绍了高速相机扫描速度不均匀性产生的原因、扫描速度测量的方法，简要地介绍了测量系统的工作原理，测时精度达到３ｎｓ，测速精度达到 ３，最后给出了测量 ＧＳＪ型和ＳＪＺ－１５型相机的结果。     

关于陀螺信号处理中小波基选取的研究

在建立陀螺漂移的数学模型的基础上，使用不同的小波基对陀螺输出信号进行多尺度小波分解，去除由噪声产生的小波系数，从而达到消除噪声的目的。从不同小波基的滤波效果来看，双正交样条小波Biorl.5具有较好的去噪效果，从而也验证了小波对称性在陀螺信号去噪中的重要性。     

Cavity nucleation, growth and stress field in elastic-plastic medium

A finite element method is used to study the cavity nucleation and growth in an elastic-plastic medium. The critical cohesion strength, _c at IPM (interface between second phase particle and matrix) is employed as the criterion of cavity formation. Three different values of _c are taken to examine their influence on the overall mechanical behaviour and process of cavity formation.     

泄爆过程中二次爆炸的动力学机理研究

在容积为0.00814m3的柱形泄爆容器中，对泄爆现象进行实验研究. 容器内充满当量比为1的甲烷-空气预混气，采用底端中心点火，泄爆压力为230±15kPa. 基于k-ε湍流模型和EBU燃烧模型，利用同位网格的SIMPLE算法，对该现象进行了数值模拟. 实验和计算获得的外轴线上4个测压点的压力曲线和外流场的阴影和数值照片，形象地描述了高压泄爆时外部流场的变化. 数值结果与实验结果基本一致. 根据实验和数值结果，详细地讨论了泄爆过程中二次爆炸产生的动力学机理. 泄爆的初始阶段，在破膜激波的引导下，泄出的未燃气体因欠膨胀在外流场形成稀疏波低压区和悬激波高压区. 高压区可燃气体密度和温度上升，成为高密度的预热区域. 随后，火焰以射流形式从泄爆口泄出，点燃可燃气云. 受湍流等因素的影响，特别在高密度的预热区域，燃烧速率可能迅速增大，从而导致二次爆炸.     

Turbulence,vortex and external explosion induced by venting

The process of explosion venting to air in a cylindrical vent vessel connected to a duct, filling with a stoichiometric methane-oxygen gas mixture, was simulated numerically by using a colocated grid SIMPLE scheme based on k-epsilon turbulent model and Eddydissipation combustion model. The characteristics of the combustible cloud, flame and pressure distribution in the external flow field during venting were analyzed in terms of the predicted results. The results show that the external explosion is generated due to violent turbulent combustion in the high pressure region within the external combustible cloud ignited by a jet flame. And the turbulence and vortex in the external flow field were also discussed in detail. After the jet flame penetrating into the external combustible cloud, the turbulent intensity is greater in the regions with greater average kinetic energy gradient, rather than in the flame front ; and the vortex in the external flow field is generated primarily due to the baroclinic effect, which is greater in the regions where the pressure and density gradients are nearly perpendicular.