水位骤变时的饱和-不饱和渗流数值计算

本文应用全隐式交替方向迭代法对水位骤变时的饱和-不饱和渗流问题求出了数值解。对于赤井模型,计算结果与实验结果十分接近,比有限元法的计算结果好。对于大尺度的驹田蓄水池模型,计算结果与有限元法的结果基本一致。     

冲击压缩下NaCl单晶光辐射特性的研究

 用光辐射技术研究了氯化钠单晶冲击压缩下的光辐射特性,得到了在45～70 GPa压力范围内NaCl单晶的光谱吸收系数随冲击压力的变化,把这一结果与Kormer等人的结果比较,发现在较低压力下与Kormer等人的结果相差较少,当压力较高时实验结果比Kormer等人的结果约大1个数量级。并用实验结果计算了电子迁移率随冲击温度的变化,得到的结果与Ziman理论基本一致,从而解决了一直来Kormer的实验结果与Ziman理论不一致的困难,进一步证明了Ziman理论的正确性。     

用质点源方法计算三维内电磁脉冲

本文给出用质点法求解三维长方腔体中的初级电流及其相应的内电磁脉冲的数值结果。井把这种方法得到的结果与三维欧拉方法的计算结果作了比较。在相同的计算条件下,两种方法得到的结果符合较好。     

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The simulation results of the plasma reconstruction were obtained and compared with the accurate balance results. With the introduction of random errors in the simulation process, robustness of the inversion procedure had been verified. The reconstruction results using the experimental data from EAST device had been compared with the inversion results from EAST’s RTEFIT to verify the correctness of the results that a single time and the continuous-time inversion. The results show that, choosing the current distribution model and magnetic diagnostic data through the equilibrium reconstruction algorithm can correctly identify the plasma shape.     

Melting of xenon monolayers - computer simulations

The results of Monte Carlo simulations of xenon monolayers deposited on graphite are presented. Systems of various surface densities and in a wide range of temperatures are investigated. The results are compared to the experimental data and to the previous results for nitrogen. The results of simulations are in good agreement with the experimental ones and confirm that melting in two dimensions is vacancy-driven. Typical real-space configurations of Xe atoms and calculated specific heat results are shown.     

柱二维内电磁脉冲的自洽计算方法(Ⅲ)

本文是[1]、[2]两篇的续篇,也是这一工作的最后一篇。其主要内容是用拉格朗日方法求解初级电子数方程组,同时给出用PIC方法、欧拉方法和该方法的数值计算结果。并把这些计算结果同非自洽方法的计算结果作了比较。当场强比较高(E>10⁵V/m)时,自洽方法自身的计算结果比较接近。当场强比较低(E≤10⁵V/m)时,两类方法的计算结果符合较好。     

Experimental investigation of asymptotic modal analysis for a rectangular plate

Experimental investigations of the response of a rectangular plate under a point random force have been performed to verify the asymptotic behavior predicted by Asymptotic Modal Analysis (AMA). Measurements have been made for various frequency bandwidths, center frequencies, and locations of the point force. The experimental results approach the results predicted by AMA as the frequency bandwidth becomes large. Moreover, experimental results show that the responses at all points of the plate except for some special areas become the same as the frequency bandwidth becomes large. However, the ratio of experimental results to AMA results has a greater variation from unity when the location of the point force is near the edge of the plate, than when the location of the point force is at the center of the plate. All experimental results show good agreement with the expected results from AMA.     

抗爆容器内爆炸流场数值模拟

 采用计算流体动力学中的二阶精度TVD差分格式和特殊算子分裂法,按轴对称问题,对半球顶圆柱筒密闭式抗爆容器内部爆炸流场进行了数值模拟。计算得到的容器壁面载荷分布与实验结果基本一致。不同时刻爆炸流场压力分布图像清晰地描述了容器壁面的冲击波加载过程。     

惰性气体原子和离子在强激光场中的隧道电离

在隧道电离区域利用ADK模型并考虑了激光的体积效应,对惰性气体原子及各价离子在强激光场中的电离产额进行了计算,并与BSI模型及实验结果进行了比较,结果发现ADK模型的结果会随着原子序数的增加而变好,尤其对Xe离子,不需要进行强度转换就能给出很好的结果．由此可以得出结论：对于重原子（或离子）,用ADK模型得到的离子产额与实验结果符合得更好．最后通过分析ADK模型的适用范围,给出了和计算结果相一致的结论．     

采样窗口对光学系统MTF测量影响的研究

对光学系统MTF测试中采样窗口对其测量影响进行了研究。在对标准镜头MTF测试时,采用离散傅里叶变换计算,线扩散函数扫描方向长度为所选针孔像线扩散函数半高宽的5倍左右时,MTF测试结果与设计值差异极值为0．011;采用快速傅里叶变换计算,线扩散函数扫描方向长度为所选针孔像线扩散函数半高宽的5倍左右时,同时采样点数要满足2^N,测试结果与设计值差异极值为0．010。为了证明此结论的普适性,按所提的采样窗口选取原则,对大像差镜头轴上和轴外的MTF进行了试验,并将测试结果与OPTIKOS的测试结果进行对比,最大极差为0．013。试验结果表明,此结论能够为光学系统MTF测试时采样窗口选择提供依据。     

临界装置实验大厅散射中子分布研究

采用蒙特卡罗方法,通过MCNP5程序对实验大厅内不同散射体产生的散射贡献及散射中子分布进行了计算。结果表明,散射中子强度随离开临界中子源距离先呈减小趋势,在接近大厅墙壁处则出现增加,呈现明显的"W"形状。同时设计并验证了模拟结果的正确性,结果表明模拟计算与实验测量结果的趋势相同,证明了计算结果的可靠性。     

Computation of triple differential cross-sections with the inclusion of exchange effects in atomic K-shell ionization by relativistic electrons for symmetric geometry

The triple differential cross-section for K-shell ionization of silver and copper atoms by relativistic electrons have been computed in the coplanar symmetric geometry with the inclusion of exchange effects following the multiple scattering theory of Das and Seal [1] multiplied by suitable spinors. Present computed results are marginally improved in some cases from the previous computed results [2]. Present results are compared with measured values [3] and with previous computation results [2]. Some other theoretical computational results are also presented here for comparison.      

Determination of equivalent salt deposit density using wind velocity for a contaminated insulator

This paper illustrates a new analytical model for determining equivalent salt deposit density (ESDD) on contaminated insulators using wind velocity. The analytical model is derived using the dimensional analysis technique. The values of ESDD from the analytical model are calculated using different values of wind velocity. These results are compared with the experimental results obtained from sites. The analytical results are also compared with the polynomial model output obtained via least-squares analysis of experimental data. It is found that the results obtained by the analytical model are quite consistent with the experimental results for different range of wind velocity.     

Experimental and Simulation Analysis of Two-Tone and Three-Tone Photodetector Linearity Characterizing Systems

Two measurement techniques are investigated to characterize photodetector linearity. A model for the two-tone and three-tone photodetector systems is developed to thoroughly investigate the influences of setup components on the measurement results. We demonstrate that small bias shifts from the quadrature point of the modulator will induce deviation into measurement results of the two-tone system, and the simulation results correspond well to experimental and calculation results.     

Impact on short length bars

A finite element method for the solution of an axisymmetric wave propagation problem of a bar of finite length is proposed. The results are obtained for a uniform bar with (i) a displacement input and (ii) a stress input. Also results are obtained for a discontinuous bar with stress input. They are compared with the existing finite difference solutions and experimental results. It is observed that the results are in close agreement. The study is then extended to the case of bars with an hemispherical end. The advantage of using the finite element method for such problems is indicated. Finally the results for a composite bar comprising a hallow cylinder and hemisphere are obtained by using the finite element method. Experiments are conducted to verify these results.     

Excited states of muonium in atomic hydrogen

Muonium formation in excited states in muon-hydrogen charge-exchange collision is investigated using a method developed in a previous paper. Differential cross-section results are found to resemble positronium formation cross-section results of positron—hydrogen charge-exchange problem. Forward differential and integrated cross-sections are computed for muon energy of 2 keV and higher. Total muonium formation cross-sections are computed using Jackson and Schiff scaling rules. Muonium formation cross-section results obtained from proton—hydrogen charge-exchange cross-section results, using velocity scaling are compared with the results of the present calculation     

凹型钝头体超音速粘性流场的数值模拟

本文首先从单个方程出发,根据TVD思想,比较自然地给出了二阶带通量限制器的CSCM^[1]差分方法,然后推广到方程组情形。为了验证方法和程序,将球头绕流计算结果同文献[2]作了比较,然后运用此方法模拟了轴对称凹型钝体的粘性超音速分离绕流流场,对一阶与二阶、粘性与无粘性数值结果作了比较。计算网格采用了简单、快速易行的拟正交代数生成方法。     

Focusing of electromagnetic waves into a biaxial crystal, experimental results

We present experimental results for focusing of an electromagnetic wave from air into a biaxial crystal. These results are compared with numerical results, and good agreement is found. The experimental results show distinct tangential and sagittal foci, whose positions agree with numerical predictions. The theory is outlined both for the exact solution, which includes extra-paraxial geometries and double refraction, and for the paraxial solution, in which double refraction is ignored. We also present a simple ray-optical interpretation of the results, which allows us to predict the positions of the sagittal and tangential foci.     

A practical comparison of surface resistance test electrodes

Four surface resistance test electrodes are compared using a selection of materials under similar test conditions. The results vary considerably with some materials due to variation in surface resistivity. Using a relatively uniform material two concentric ring electrodes compliant with the same standard differed in results by a factor of 1.8. Silver stripe and copper tape electrodes gave results a factor 0.4 and 0.7 compared to the reference electrode. A 2-pin electrode gave results a factor 4.7 greater. The 2 pin probe cannot be expected to give similar results to the other electrodes for materials that have variable resistivity.     

耦合带状线定向耦合器大功率合成器的设计

介绍了直线加速器高频全固态功率源中大功率合成器件-3 dB定向耦合器的理论计算和工程设计过程, 该合成器工作频率80.5 MHz, 输出连续波功率大于20 kW。 分析了合成器的功率容量, 并对相应的理论计算结果、 CST (Computer Simulation Technology)软件模拟计算结果和实际功率合成器件测量结果进行了比较。 通过比较得出, CST仿真结果与测试结果基本一致, 隔离度和电压驻波比等实测指标优于设计指标, 只有耦合度与设计指标有些偏差, 总体上达到了预期的设计要求。 在输出功率20 kW时, 取样波形无失真, 合成器无明显温升, 满足固态功率源大功率稳定运行的要求。 The principle of design and calculation of the power synthesis in the solid state amplifier are described in this paper. The working frequency of the synthesizer is 80.5 MHz. The output continuous wave power is more than 20 kW; The synthesizer power capacity is analyzed. The theoretical calculation results, Computer Simulation Technology (CST) simulated results are compared with the measured results of the actual 3 dB couplers. The analysis of the measured results and CST calculated results shows that the simulation is in agreement with the measurement results which meet the design requirements of the solid state amplifier. Except the coupling coefficient, the isolation, the VSWR and other parameters are better than the design target. When the output power is 20 kW, the sampling waveform has no deform and the temperature of the synthesizer is stable.