随机变量间一种新的散布函数

设ＤＸ（ｔ）＝Ｅ｜Ｘ－ｔ｜，ｔ∈Ｒ，定义一种散布函数Ｄ＊Ｘ（ｔ）＝１２［ＤＸ（ｔ）＋ＤＸ（－ｔ）］．这种散布函数导出了一种新的散布序。

关于分布函数的散布函数

研究了一种散布函数Ｄｘ（ｔ）的性质，得到了如下结论：设Ｘ～Ｎ（μ１，σ１２），Ｙ～Ｎ（μ２，σ２２）。

分布函数间一种新的散布序

设Ｆ是一分布函数，对α∈（０，１），记Ｘ_Ｆ~＋（α）＝ｓｕｐ｛ｘ；Ｆ（ｘ）＜α｝，Ｘ_Ｆ~－（α）＝ｉｎｆ｛ｘ；Ｆ（ｘ）＞α｝，ＸＦ（α）＝（Ｘ_Ｆ~＋（α）＋Ｘ_Ｆ~－（α））／２．本文给出了分布函数Ｆ和Ｇ之间的一种散布序，记作；对α，β∈（０，１），α＜β，ＸＦ（β）－ＸＦ（α）＋ＸＦ（１－α）－ＸＦ（１－β）≤ＸＧ（β）－ＸＧ（α）＋ＸＧ（１－α）－ＸＧ（１－β），得到了这种序关系的若干性质，并与Ｌｅｗｉｓ Ｔ和Ｔｈｏｍｐｓｏｎ Ｍ（１９８２）给出的散布序作了比较，我们的序关系弱于Ｌｅｗｉｓ Ｔ和Ｔｈｏｍｐｓｏｎ Ｍ给出的散布序关系．

基于延迟-移频的SAR有源欺骗干扰有效区域研究

基于延迟-移频的SAR有源欺骗干扰方法具有局部区域有效性,有效区域的研究是合理运用干扰、确保达到欺骗效果的基础。该文通过分析干扰信号与真实点目标回波的差异,指出影响干扰信号聚焦的因素为残余距离单元徙动、方位向匹配滤波器失配和多普勒带宽损失,得到了延迟-移频干扰有效区域的解析表达式,并用仿真结果验证了理论分析的正确性。研究表明,基于延迟-移频的SAR有源欺骗干扰适用于干扰机附近小范围区域的防护。

圆周SAR与线性SAR成像特性分析与对比

圆周合成孔径雷达因其独特优势已经成为雷达领域的研究热点。分析圆周合成孔径雷达与线性合成孔径雷达在成像区域大小、点散布函数特性、回波频谱特点、三维成像能力等方面的差异,凸显了圆周合成孔径雷达的成像特点。发现单航过圆周合成孔径雷达频域成像处理的难点在于其回波频谱的空变性。为提高频域成像处理的效率,分析了平面圆周合成孔径雷达与多航过圆周合成孔径雷达成像模式,并指出这两种模式易于在频域开展一致化处理。仿真试验证明了分析内容的正确性。

视频序列中自适应背景的运动目标提取

在视频序列的运动目标实时检测中常用的方法是背景差分法,但因背景图像未随监视场景光照变化及时更新而限制了本方法的适应性.对此,本文首先提出了一种自适应背景更新方法,得到差分二值图像;然后引入散布函数准则计算出差分图像的最佳分割阈值,实现运动目标的自适应阈值分割.实验结果表明:本文提出的背景更新方法可随着光照条件的变化实时、准确地更新背景图像,在此基础上提出的基于散布函数准则的自适应阈值分割方法可以实现运动目标的完整分割,这为运动目标的后续识别与理解奠定了基础.

Density distribution in a heavy-medium cyclone

Heavy-medium cyclones are widely used to upgrade run-of-mine coal.But the understanding of flow in a cyclone containing a dense medium is still incomplete.By introducing turbulent diffusion into calculations of centrifugal settling a theoretical distribution function giving the density field can be deduced.Qualitative analysis of the density field in every part of a cylindrical cyclone suggests an optimum design that has exhibited good separation effectiveness and anti-wear performance when in commercial operation.

β-Diketones at Water/Supercritical CO2 Interface： A Molecular Dynamics Simulation

The structural and dynamical properties of hexafluoroacetylacetone(HFA) and acetylacetone(AA) at the water/supercritical CO2(Sc-CO2) interface at 20 MPa and 318.15 K are investigated by molecular dynamics simulations.The TIP3P potential is used for water and the EPM2 model is for CO2.The water phase and SC-CO2 phase form a distinct immiscible liquid-liquid interface.The two chelating molecules show interfacial preference.Comparatively,the AA molecules show somewhat more preference for interfacial region,whereas the HFA molecules are preferably near the Sc-CO2 phase.The orientational distribution of the β-diketone molecules and the radial distribution functions between β-diketones and solvents are obtained in order to study the microscopic structural properties of the β-diketones at the water-SC-CO2 interface.It is found that the translational diffusion and rotational diffusion of HFA and AA are obviously anisotropic and decrease as the β-diketone molecules approach the interface.The anisotropic dynamic behavior for the solute molecules is related to the corresponding structural properties.

Extraction of Structure Function and Gluon Distribution Function at Low-x from Cross Section Derivative by Regge Behavior

An approximation method based on Regge behavior is presented. This new methodrelates the reduced cross section derivative and the structure function Regge behavior at low x.With the use of this approximation method, the C and λ parameters are calcuiated from the HERAreduced cross section data taken at low-x. Also, we calculate the structure functions F_2(x, Q~2)even for low-x values, which have not been investigated. To test the validity of calculatedstructure functions, we find the gluon distribution function in the Leading order approximationbased on Regge behaviour of structure function and compare to the NLO QCD fit to H1 data and NLOparton distribution function.

Comparison study of several underwater light scattering phase functions

Scattering phase function is assumed to be one of the most significant factors in the inherent optical properties （lOPs） of natural water. According to three criteria proposed for assessment, several commonly used empirical phase functions are compared with their related practical or theoretical scattering distributions in terms of fitting errors under the circumstances of typical seawater and single-component polydisperse systems. The optimal factors corresponding to the minimum fitting errors are also calculated. It is found that both the one-term Henyey-Greenstein （OTHG） and two-term Henyey-Greenstein （TTHG） phase functions agree well with the theoretical ones for small particles, while the Fouriner-Forand （FF） phase function can be used in the case of suspensions with large suspended particles. The fitting accuracy of OTHG is the worst, FF is better and TTHG is the best.