New Receiving Mode of Extinction for Determining Particle Size and Density without Convex Lens

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｉｆａｌｉｇｈｔｂｅａｍ ｐａｓｓｅｓｔｈｒｏｕｇｈｔｈｅｐａｒｔｉｃｕｌａｔｅｔｒａｎｓｐａｒｅｎｔｍｅｄｉｕｍ ,ｉｔｓｉｎｔｅｎｓｉｔｙｗｉｌｌｂｅｗｅａｋｅｎｅｄｂｅｃａｕｓｅｏｆｔｈｅｅｘｔｉｎｃｔｉｏｎｏｆｐａｒｔｉｃｌｅｓ[1] .Ｔｈｉｓｐｈｅｎｏｍｅｎｏｎｉｓｃａｕｓｅｄｂｙｔｈｅｓｃａｔｔｅｒｉｎｇａｎｄａｂｓｏｒｐｔｉｏｎｏｆ ｐａｒｔｉｃｌｅｓ.Ｔｈｅｓｃａｔｔｅｒｉｎｇｅｌｅｃｔｒｏｍａｇｎｅｔｉｃｗａｖｅｓａｒｅｄｉｆｆｕｓｅｄｉｎｓｐａｃｅａｌ…     

最小偏差分析法在经济周期分析中的应用

利用最小偏差分析法,分析了我国GDP增长率的周期性特征,并对我国今后几年的GDP增长率进行了预测.分析的结果是:从1953—2006年,我国GDP增长率存在着7年左右的小周期,15年左右的中周期,19年左右的中长周期和28年左右的大周期,而且随着时间的推移,经济周期的波动幅度逐渐趋小,反映出经济增长的稳定性增强.预测的结果是:今后几年(2年或更长一段时间)我国GDP增长率应该保持在10%左右,波动的区间为[9%,11%].     

半导体激光列阵泵浦连续和准连续Nd：YAG激光器稳定输出

用连续输出100mw和脉冲输出200mW的国产双异质结激光二极管(DH-LD)泵浦Nd:YAG激光器,得到稳定的半导体激光泵浦的固体激光器连续输出12mW和10～50kHz重复频率的准连续输出,每个脉冲激光峰值功率20mW,起伏小于1%,与计算结果基本一致.     

用涨落模型解释有关主被动锁模Nd:YAG激光器的若干问题

应用锁模理论的涨落模型分析研究了已报道的若干主被动锁模Nd:YAG激光器的实验现象.对锁模的阈值行为,锁模几率随调制器调制功率的变化规律和系统的稳定性随可饱和吸收染料的相对浓度的变化规律等实验结果从理论上进行了比较成功的解释.     

微光成像系统的阈值探测理论和视距探测方程的研究

研究目前文献中常见的１８种微光成像系统探测方程之间的内在联系和异同之处，分析论证各种阈值探测理论和探测方程存在的问题和不足。在此基础上，从人眼的视觉理论和阈值特性出发，建立微光成像系统新的阈值探测理论模型，并分别导出微光直视系统和微光电视系统的视距探测方程。应用所导出的理论公式计算的数据与各种实际系统的实测数据进行了比较，证明新的阈值探测理论和视距探测方程是正确可靠的，且具有很高的精度。     

New Receiving Mode of Extinction for Determining Particle Size and Density without Convex Lens

In this article a new receiving mode for scattering light by particle is theoretically discussed. Using this receiving mode the convex lens can be omitted during determining the extinction of particle. Therefore the extinction coefficient of sphere particles is redefined by extrapolating the conventional one. In terms of the calculation results of light scattering the definition of near-field extinction coefficient of a swarm particle is depicted. Through the error analysis it is proved that the error coming from the new definition of extinction coefficient is acceptable for engineering application. In addition, a technique for determining the particle size and density is presented in this article and the advantage using this receiving mode is described.     

Electronic structure and magnetism of YbRhSn

The electronic band structure of YbRhSn has been calculated using the self-consistent full potential nonorthogonal local orbital minimum basis scheme based on the density functional theory. We investigated the electronic structure with the spin-orbit interaction and on-site Coulomb potential for the Yb-derived 4f orbitals to obtain the correct ground state of YbRhSn. The exchange interaction between local f electrons and conduction electrons play an important role in the heavy fermion characters of them. The fully relativistic band structure scheme shows that spin-orbit coupling splits the 4f states into two manifolds, the 4f_7/2 and the 4f_5/2 multiplet.     

Plankton growth dynamic driven by plankton body size in deterministic and stochastic environments

In this paper, we establish a new phytoplankton–zooplankton model by considering the effects of plankton body size and stochastic environmental fluctuations. Mathematical theory work mainly gives the existence of boundary and positive equilibria and shows their local as well as global stability in the deterministic model. Additionally, we explore the dynamics of V-geometric ergodicity, stochastic ultimate boundedness, stochastic permanence, persistence in the mean, stochastic extinction, and the existence of a unique ergodic stationary distribution in the corresponding stochastic version. Numerical simulation work mainly reveals that plankton body size can generate great influences on the interactions between phytoplankton and zooplankton, which in turn proves the effectiveness of mathematical theory analysis. It is worth emphasizing that for the small value of phytoplankton cell size, the increase of zooplankton body size can not change the phytoplankton density or zooplankton density; for the middle value of phytoplankton cell size, the increase of zooplankton body size can decrease zooplankton density or phytoplankton density; for the large value of phytoplankton cell size, the increase of zooplankton body size can increase zooplankton density but decrease phytoplankton density. Besides, it should be noted that the increase of zooplankton body size cannot affect the effect of random environmental disturbance, while the increase of phytoplankton cell size can weaken its effect. There results may enrich the dynamics of phytoplankton-zooplankton models.     

高超音速湍流分离表面热流率的脉动特性

本文给出高超音速湍流分离不稳定特性的实验研究结果。试验条件是:自由流马赫数为 7.8,单位长度雷诺数为 3.5×10~7/米。分离流场由有限展长前向台阶产生,并用有高空间分辨率和快速响应的一列平齐安装的铂膜电阻温度计和多通道系统测量其表面热流率脉动。信号的条件采样分析结果表明:分离激波的根部由一束压缩波构成,流向展长约二分之一来流边界层厚度,在边界层外汇聚成单一主激波。这种激波结构极其不稳定,出现大尺度运动,流向运动的尺度约为分离激波上游影响区域长度的22％。激波振荡频率为一宽频带,主要集中在 1～3 千赫。在分离激波运动区域,热流脉动呈间歇性,在无扰动和激波扰动间跳跃。可以认为这种间歇性是分离激波系统大尺度振荡的结果。在激波运动区域的下游为分离区,流体继续压缩,热流脉动无间歇。     

阻抗式和简单调压室甩荷时水位波动的显式计算方法

目前对调压室水位波动的研究主要有图解法和数值计算。尚未看到考虑阻力项后调压室水位波动随时间变化的显函数计算方法。本文从调压室的基本微分方程出发，采用泰勒级数展开式推导了阻抗式和简单式调压室甩荷时水位波动的显式计算方法。运用这种方法不仅可以计算调压室水位波动的过程，而且可以方便的计算调压室的最高涌浪和第二振幅。