A new automatic exposure algorithm for video cameras using luminance histogram

Automatic exposure (AE) is one of the indispensable functions of modern video cameras. According to the attention mechanism of human visual systems, peak regions in luminance histogram correspond to the region of no interest in an image. Based on this assumption, a new AE algorithm using the luminance histogram of an image is proposed in this paper. The algorithm finds the first two largest peak regions in the histogram and calculates the mean weighted luminance (MWL) of the entire image by weighting the luminance of pixels inside the two peak regions. The MWL is then used to control the exposure of video cameras. The weight of pixel luminance is decided by a set of quadratic curves, and the parameters of the quadratic curves are affected by the brightness of the image background. Fuzzy logic is also applied to optimize the practical AE systems. Results show that the proposed algorithm gives efficient exposure control over various scene tests.     

静水中正方形孔口的有障碍浮射流(Ⅱ)——流场特性分析

在数值计算成果的基础上,对正方形阻力盘浮力射流的流场进行了分析和总结,基于轴线流速的变化规律将盘后流场分为3个区域:回流区、过渡区和自相似区．验证了竖直方向流速自相似性的存在．根据给出的轴线流速的变化图也可以区分盘后3个区域的位置,同时发现各工况在自相似区域的轴线流速沿同一规律曲线变化,采用Chen和Rodi对流速的表示方法,得到了所有工况下自相似区域轴线流速的分布公式．给出了典型工况下阻力盘后不同高度位置处的压强场等值线变化过程,发现盘后各负压中心区域的产生、膨胀、破裂和消失．     

Study on electrochemical fingerprints of different Chrysanthemums by using B-Z oscillation system

A sensitive and convenient method for the study of electrochemical fingerprints of Chrysanthemums from different regions is studied by Belousov-Zhabotinskii(B-Z) oscillation system with malonate as a dissipative material.The results indicated that the electrochemical fingerprints of Chrysanthemums from different regions show significantly different characteristics,and can be used to identify the regions of Chrysanthemums.     

一种改进的显著区域提取模型

图像的显著区域代表的是图像的主要内容,提取显著区域在图像检索、压缩、识别等方面有重要的应用。基于Itti模型提出一种改进的模型来提取图像的显著区域,即分别提取原始图像的亮度、颜色、方向、形状四个特征,并将这四个特征的多尺度图像特征合并成一幅总的显著图;在图像方向特征提取中采用倒数函数来代替Gabor特征函数,使得方向特征图更加完善。该模型与经典的Itti模型相比较,提取出的显著图更为明显,速度较快且易于实现。     

基于MDS和SDP的分布式节点定位算法

提出一种新的节点定位算法,基于MDS和SDP的分布式节点定位算法(DLMS)。该算法的主要思想是将整个无线传感器网络划分成若干个局部定位区域,在每个局部定位区域选择MDS定位算法或SDP定位算法建立一个局部相对定位图,然后将所有的局部相对定位图合并成全局相对定位图,最后利用锚节点的信息得到节点的估计位置。实验仿真结果表明,该算法能够提高节点的定位精度,尤其是在节点分布不均匀的情况下,同时该算法还能够节约锚节点数量。     

一种应用于全球导航卫星系统接收机的低功耗宽带压控振荡器

该文设计了一种应用于全球导航卫星系统(GNSS)射频接收芯片的新型低功耗小面积宽频率调节范围的压控振荡器(VCO)。根据全波段GNSS信号的特点,将VCO分成两个离散的频率工作区域,可分别对这两个区域进行功耗、相位噪声的优化,减小了VCO结构的复杂度,并节省了芯片面积。利用调谐曲线线性化技术,克服了传统的VCO控制电压有效调节范围窄的问题,使VCO在整个控制电压范围内调节曲线线性,减小了幅度调制转频率调制(AM-FM),降低了相位噪声。测试结果显示,该VCO频率调节范围为49.5%,控制电压在0.1~0.9 V内,VCO增益(KVCO)恒定,当频率偏移为1 MHz时相位噪声小于-120 dBc/Hz,消耗电流2 mA,占用芯片面积为0.24mm2。提出的VCO在0.13μm 1P6M工艺上实现,已成功应用于全波段GNSS接收机中。     

AVS标准中的灵活条带结构

通过对AVS和H.264/AVC中条带层语法的比较分析,针对现有条带相关技术的不足,在图像层和条带层之间,提出了灵活条带集技术。通过辅以非均衡差错保护策略,采用灵活条带集技术可以增强关注区域的抗误码能力。同时,可通过对条带集量化参数的调整实现基于区域的变质量编码,在总码率相当的情况下大大增强了关注区域的主客观质量。     

Weighted-mean regions of a probability distribution

In this paper we investigate a new class of central regions for probability distributions on R^d, called weighted-mean regions. Their restrictions to an empirical distribution are the weighted-mean trimmed regions investigated by Dyckerhoff and Mosler (2011) for d-variate data. Furthermore a new class of stochastic orderings of variability, the weighted-mean orderings, is introduced.     

The electric potential of tripolar spikes

We present an analytical formula for the waveform of the electric potential associated with a tripolar spike in a plasma. This formula is based on the construction and on the subsequent solution of a differential equation for the waveform. We work out this equation as a direct consequence of the morphological and functional properties of the observed waveform, without making any reference to the velocity distributions of the electrons and of the ions which sustain the spike. In the approximation of small potential amplitudes, we solve this equation by quadrature. In particular, in the second order approximation, the solution of this equation is given in terms of elementary functions. This analytical solution is able to reproduce the potential waveforms associated with electron holes, ion holes, monotonic and nonmonotonic double layers and tripolar spikes, in excellent agreement with observations.