On general form of Navier-Stokes equations and implicit factored scheme

A general weak conservative form of Navier-Stokes equations expressed with respect to non-orthogonal Curvilinear coordinates and with primitive variables was obtained by using tensor analysis technique, where the contravariant and covariant velocity components were employed. Compared with the current coordinate transformation method, the established equations are concise and forthright, and they are more convenient to be used for solving problems in body-fitted curvilinear coordinate system. An implicit factored scheme for solving the equations is presented with detailed discussions in this paper. For n-dimensional flow the algorithm requires n-steps and for each step only a block tridiagonal matrix equation needs to be solved. It avoids inverting the matrix for large systems of equations and enhances the speed of arithmetic. In this study, the Beam- Warming’s implicit factored schceme is extended and developed in non-orthogonal curvilinear coordinate system.     

建筑物爆炸泄压的试验研究

本文报导了在1米~3和30米~3两个爆炸泄压试验装置内进行的360余次试验结果。证明了在有平行壁面的建筑物内发生的可燃气爆炸泄压过程中,声动不稳定燃烧压力峰P3是建筑物的主要破坏因素。试验表明,本文发展的一种爆炸减压板具有消除P3的效应。     

铋系氧化物高温超导相晶格软化研究

本文报道了在液氮温区以上铋系高 T_c 超导相变温穆斯堡尔谱的实验结果.穆斯堡尔无反冲因子随温度变化表明,在超导转变温度 T_c 以上,铋系高 T_c 相的 Cu-O 层中出现了明显的晶格软化现象,这种与晶格软化相联系的结构不稳定行为可认为是超导转变的前驱效应.在 Cu-O 层上发生的品格软化的特殊性质,对超导电性的影响不能忽略.     

Upgrade of beamline 3W1B at Beijing Synchrotron Radiation Facility

To improve the performance of Beamline 3W1B at the Beijing Synchrotron Radiation Facility for the soft X-ray magnetic linear dichroism research at transition metals L_{2, 3} edges, a new monochromator was designed and built to replace the original one. After the assemblage, alignment and adjustment of the monochromator system, the first commissioning results were obtained. The photon energy range is from 50 to 1000 eV with spectral resolutions of 1600 at 250 eV and 1000 at 870 eV. The photon flux is of the order of 10⁸-10⁹ photons/s/200 mA/0.1%BW. In the electron's orbital plane the linear polarization degree of the light is higher than 99% at 704 eV. The beamline has satisfied the basic experimental requirements.     

Optical properties of InGaAsBi/GaAs strained quantum wells studied by temperature-dependent photoluminescence

The effect of bismuth on the optical properties of InGaAsBi/GaAs quantum well structures is investigated using the temperature-dependent photoluminescence from 12 K to 450 K.The incorporation of bismuth in the InGaAsBi quantum well is confirmed and found to result in a red shift of photoluminescence wavelength of 27.3 meV at 300 K.The photoluminescence intensity is significantly enhanced by about 50 times at 12 K with respect to that of the InGaAs quantum well due to the surfactant effect of bismuth.The temperature-dependent integrated photoluminescence intensities of the two samples reveal different behaviors related to various non-radiative recombination processes.The incorporation of bismuth also induces alloy non-uniformity in the quantum well,leading to an increased photoluminescence linewidth.     

基于多重散射强度和偏振特征的舰船尾流气泡激光探测方法

研究多重散射效应对舰船尾流气泡群光散射强度和偏振特征的影响是舰船光尾流探测以及新型光自导鱼雷研究的基础. 基于矢量Monte Carlo方法建立了舰船尾流气泡群激光后向探测仿真模型, 重点研究了尾流气泡群的多重散射机理,分析了多重散射效应、尾流气泡群密度对回波信号强度和偏振特征的影响规律. 基于粒子碰撞重要性抽样的基本思想, 在传统能量接收方法的基础上, 提出了回波光子偏振贡献接收方法和回波信号偏振信息统计方法, 解决了小视场系统光子返回概率低无法形成回波能量的难题. 构建了模拟尾流气泡群激光散射强度和偏振探测实验平台, 从实验的角度验证了模拟结果的准确性. 实验和模拟结果的一致性表明, 利用回波强度、偏振信息可表征气泡群距离、密度信息, 从而可对舰船尾流特别是低密度尾流进行高精度的探测和辨识. 关键词： Monte Carlo 偏振 多重散射 气泡     

在柱坐标系中求解轴对称的静电场

提出了求解轴对称静电场的柱函数展开法,推导出用对称轴上的电势分布表示空间电势分布的级数展开式,并给出了求解轴对称静电场的例子.     

非定常膨胀过程中水蒸汽凝结对流场影响的数值分析

采用数值目的对激波管非定常膨胀过程中,汽液相变与流场的相互作用进行了模拟.主要研究了含有水蒸汽的混合气体在激波管中的非平衡凝结过程以及其对流场的作用.结果表明由于水蒸气的凝结释放热量对流场局部进行加热,使流场参数发生扰动而产生凝结激波.经过与凝结激波的相互作用后,流场参数和结构将发生明显的变化.