遥感相机中时间延时积分电荷耦合器件 积分级数的最优选择

针对时间延时积分电荷耦合器件积分级数对成像质量的影响,提出了一种航天遥感相机中时间延时积分电荷耦合器件积分级数的最优选择方法.构造了典型成像系统的信噪比与积分级数关系模型和调制传递函数与卫星姿态角和积分级数的函数模型;以信噪比和调制传递函数的容许值为约束条件,推导出了任意条件下时间延时积分电荷耦合器件的可选积分级数区间并给出了最优的积分级数解,给出了对应的增益设置指导函数.运用仿真实验对该方法进行验证,并与传统方法进行比较,结果表明:该方法能够选取最优的积分级数,从而获得满足信噪比和调制传递函数指标的最佳成像质量;若该值不存在,依然能获取相对最佳的折中值和视觉效果;同时,本文成像效果优于传统方法.     

多光束非定域干涉反射光强分布

研究了多光束非定域干涉现象,得到了多光束非定域干涉的反射光强分布函数.数值计算结果表明:随着镜面反射系数的增加,多光束非定域干涉条纹半值宽度降低,条纹变得更加锐细,光谱分辨率提高;当镜面反射率较高时,除了暗条纹外,在低干涉级次处紧邻暗条纹还有很窄的亮条纹存在;亮条纹振幅逐渐衰减至背景光强度,干涉级次越低亮条纹振荡越明显;第一束反射光提供了一个均匀的背景,第二束反射光的加入产生了双光束干涉,干涉条纹较粗,对比度较低,更多光束的加入使干涉暗条纹变得锐细,在相邻暗条纹间出现了明暗相间的低强度明暗条纹;足够多光束的加入使相邻暗条纹间低强度变化的明暗条纹消失,同时在紧邻暗条纹处出现了振幅振荡衰减的亮条纹.最后,将多光束非定域干涉理论应用于光学滤波器的研究,结果表明:提高镜面反射率,可以显著降低多光束非定域干涉的滤波带宽;改变镜面间距,可以灵活调整多光束干涉仪滤波波长和相消波长间距.     

Diversity of photonic differentiators based on flexible demodulation of phase signals

We theoretically propose a multifunctional photonic differentiation （DIFF） scheme based on phase demodulation using two cascaded linear filters. The photonic D1FF has a diversity of output forms, such as the 1 st order intensity DIFF, the 1 st order field DIFF and its inversion, and the 2nd-order field DIFF, depending on the relative shift between the optical carrier and the filter＇s resonant notches. As a proof, we also experimentally demonstrate the DIFF diversity using a phase modulator and two delay interferometers （Dis）. The calculated average deviation is less than 7% for all DIFF waveforms. Our schemes show the advantages of flexible DIFF functions and forms, which may have different optical applications. For example, high order field differentiators can be used to generate complex temporal waveforms, and intensity differentiators are useful for the ultra-wideband pulse generation.     

Icosahedral quasicrystals solids with an elliptic hole under uniform heat flow

The complex variable method for solving the two-dimensional thermal stress problem of icosahedral quasicrystals is stated. The closed-form solutions for icosahedral quasicrystals containing an elliptical hole subjected to a remote uniform heat flow are obtained. When the hole degenerates into a crack, the explicit solutions for the stress intensity factors is presented.     

Memristance controlling approach based on modification of linear M–q curve

The memristor has broad application prospects in many fields, while in many cases, those fields require accurate impedance control. The nonlinear model is of great importance for realizing memristance control accurately, but the im- plementing complexity caused by iteration has limited the actual application of this model. Considering the approximate linear characteristics at the middle region of the memristance-charge （M-q） curve of the nonlinear model, this paper pro- poses a memristance controlling approach, which is achieved by linearizing the middle region of the M-q curve of the nonlinear memristor, and establishes the linear relationship between memristances M and input excitations so that it can realize impedance control precisely by only adjusting input signals briefly. First, it analyzes the feasibility for linearizing the middle part of the M-q curve of the memristor with a nonlinear model from the qualitative perspective. Then, the lin- earization equations of the middle region of the M-q curve is constructed by using the shift method, and under a sinusoidal excitation case, the analytical relation between the memristance M and the charge time t is derived through the Taylor series expansions. At last, the performance of the proposed approach is demonstrated, including the linearizing capability for the middle part of the M-q curve of the nonlinear model memristor, the controlling ability for memristance M, and the influence of input excitation on linearization errors.     

浅谈2011年高考题中出现的数形结合

数形结合思想是一种很重要的数学思想.数学研究的对象是数量关系和空间形式,即数与形两个方面,把数量关系的研究转化为图形性质的研究,或者把图形性质的研究转化为数量关系的研究,这种解决问题过程中“数’”与“形”相互转化的研究策略,就是数形结合的思想.数形结合思想就是要使抽象的数学语言与直观的图形结合起来,使抽象思维与形象思维结合起来.在使用的过程中,由“形”到“数”的转化,往往比较明显,而由“数”到“形”的转化却需要转化的意识,因此,数形结合思想的使用往往偏重于由“数”到“形”的转化.在一维空间,实数与数轴上的点建立一一对应关系;在二维空间,实数对与坐标平面上的点建立一一对应关系.特别是集合、函数、不等式、数列、向量、解析几何、导数与积分等能够用图形表述的知识点,就要用数形结合形象化,高考在选择题、填空题侧重考查数到形的转化,在解答题中,考虑推理论证的严密性,突出形到数的转化.下面谈谈数形结合思想在2011年高考中的体现.     

不同的数学问题源于同一个函数模型

近来几个出现在多家刊物上的数学问题引起笔者的兴趣,经过研究发现,尽管它们的表述形式不同,考查方向不一,解决办法多样,但笔者认为它们的内涵一致、背景相同,共生于一个函数,倘     

室内环境下基于图优化的UWB定位方法

针对室内三维环境中对定位结果准确性的要求,提出了一种基于图优化的室内超宽带(UWB)定位算法。首先,利用最小二乘法对UWB技术测量的距离进行解算,得到第一次定位初值。然后,将第一次定位初值代入泰勒级数展开算法,得到更可靠的第二次定位初值。最后,建立包括定位残差和位移残差两项的目标函数,通过基于图优化的算法,得到目标函数的最小值,计算出优化之后的最终定位结果。通过样机实验验证定位精度,实验结果表明平均水平定位误差小于10 cm,同时平均高度定位误差也比相同实验条件下使用Chan算法和改进的卡尔曼滤波方法分别低了77%和61%。     

无穷级数引入的教学设计

给出针对无穷级数引入的一种教学设计.以趣味故事作为实例引入,通过对π的计算这个实际问题的讲解,让学生抓住概念的本质,并对无穷级数的应用有一个初步的了解,从而对无穷级数有一个总体的认识.在教学过程中,步步引导,全程既具有趣味性又具有启发性.     

FURTHER APPLICATIONS OF POLAR COORDINATES IN C~n

Simplify the proof on the domain of convergence of multiple power series and consider the case where some of z1, ··· , zn are contained only in a finite number of terms of the series. Obtain some results on holomorphic functions in Cn.