SS Cyg爆发时连续谱的偏振

本文利用改进了的盘大气(加上冕结构),计算了SS Cyg爆发时连续谱的线偏振,结果表明:紫外波段的线偏振明显高于光学波段;波长λ?2000A时,偏振度大小随质量吸积率M增加而增加,λ<2000A 时则反之.爆发期间,偏振度皆为负,这是由于SS Cyg较小的吸积盘倾角所致.比较了利用标准恒星大气模型(Ku-rucz模型大气)所计算的结果,发现当M较大时,利用恒星大气所得的紫外波段的偏振度转为正值,这是由于该大气下不透明度较高的缘故.利用紫外波段的线偏振观测,将有利于对盘大气合理性的鉴别.     

对高灵敏电流计零点飘移根源的商榷

本刊1988第5期刊登的“高灵敏电流计的零点飘移及由此引起的内阻测量误差与消除”(以下简称“零飘研究”)提出零点飘移的根源主要应是空间电磁波的影响。为了弄清实验教学中这一问题,我们也做了一些探讨,但结果表明,温差电动势应是零点飘移的主要根源。现将实验结果与分析介绍如下。     

光流控流式细胞术的研究进展北大核心CSCD

光流控是一项将光学和微流控技术结合起来,在微芯片上实现部分种类细胞计数、分选等功能的新技术。近些年来伴随着光流控技术的蓬勃发展,流式细胞仪小型化、价格下降以及更紧凑的趋势逐渐明显,而这将会给医疗保健诊断以及某些疾病的预防检测带来极大的便利。对目前该领域液流控制、照明及探测光学、新型分选装置等方面的最新进展进行了介绍。     

分区迭代计算流动问题中重叠边界的处理

本文首先采用四种重叠边界的处理方法,对顶盖驱动流动问题进行了分区迭代并行计算,探讨分区迭代并行计算流动问题时重叠边界处理方法对计算时间和计算精度的影响。计算结果表明,当采用一个网格重叠迭代计算时,计算结果具有明显的误差;多个网格重叠计算精度较高,但重复的计算量很大,失去了并行计算提高计算速度的意义;而采用无网格重叠与两...     

锕系端基亚胺金属有机化合物研究进展

在过去的30多年中,锕系端基亚胺金属有机化合物因其具有独特的结构特征以及在基团转换与催化方面的潜在应用而受到人们的广泛研究,并取得了一些很好的成果.目前,锕系端基亚胺金属有机化合物已成为金属有机化学领域中一个引人注目的研究热点.这篇综述主要介绍了锕系端基亚胺金属有机化合物在合成及反应性能方面的研究进展.     

Copper ion beam emission in solid electrolyte Rb4Cu16I6.5Cl13.5

Copper ion conducting solid electrolyte Rb$_{4}$Cu$_{16}$I$_{6.5}$Cl$_{13.5 }$ was prepared by means of mechano-chemical method. The structure and morphology of the powder was investigated by x-ray diffraction and scanning electron microscopy. The grain size was estimated to be 0.2-0.9 μm and the ionic conductivity at room temperature was approximately 0.206 S/cm. The solid electrolyte Rb$_{4}$Cu$_{16}$I$_{6.5}$Cl$_{13.5 }$ was exploited for copper ion beam generation. The copper ion emission current of several nA was successfully obtained at acceleration voltages of 15 kV and temperature of 197 $^\circ$C in vacuum of 2.1$\times10^{-4}$ Pa. A good linear correlation between the logarithmic ion current $(\log I)$ and the square root of the acceleration voltage ($U_{\rm acc}$) at high voltage range was obtained, suggesting the Schottky emission mechanism in the process of copper ion beam generation.     

低强度脉冲伽马辐射测量中LaCl_3、YAG∶Yb和CeF_3闪烁探测器优选

为了在低强度脉冲伽马辐射测量中获得更精密可靠的测试数据,对La Cl3(50 mm×30 mm)、YAG∶Yb(50mm×50 mm)两种新型闪烁探测器和常用Ce F3(45 mm×20 mm)闪烁探测器的灵敏度、伽马/中子甑别能力、时间响应特性、统计涨落等主要参量进行了实验测量和对比。实验测量结果表明:La Cl3闪烁探测器灵敏度最高;伽马/中子甑别能力比另两种闪烁探测器高1倍以上;时间响应与Ce F3闪烁探测器相当;统计涨落最小(测点注量率相当的情况下)。进行中子、伽马混合脉冲辐射场中的低强度脉冲伽马辐射测量时,三种闪烁探测器中,La Cl3闪烁探测器是一种更佳的实用候选闪烁探测器。     

Characterizing a proton beam with two different methods in beam halo experiments

In beam halo experiments, it is very important to correctly characterize the RFQ output proton beam. In order to simulate the beam dynamics properly, we must first know the correct initial beam parameters. We have used two different methods, quadrupole scans and multi-wire scanners to determine the transverse phase-space properties of the proton beam. The experimental data were analyzed by fitting to the 3-D nonlinear simulation code IMPACT. For the quadrupole scan method, we found that the RMS beam radius and the measured beam-core profiles agreed very well with the simulations. For the multi-wire scanner method, we choose the case of a matched beam. By fitting the IMPACT simulation results to the measured data, we obtained the Courant-Snyder parameters and the emittance of the beam. The difference between the two methods is about eight percent, which is acceptable in our experiments.     

$C_3$型的退化Ringel-Hall代数的Gr\"{o}bner-Shirshov基

The Gr?bner-Shirshov basis of the degenerate Ringel-Hall Algebras of type C₃ is obtained by studying the generic extension monoid algebra.