拉曼差分法探测大气中的臭氧

介绍了拉曼差分法测量对流层底部污染物O_3的基本原理。计算和研究了N_2,O_2的拉曼光谱强度分布特征,利用O_3对N_2,O_2紫外波段拉曼散射光的不同吸收特性,推导出O_3浓度反演公式;设计了拉曼差分激光雷达(Raman-DIAL)系统,该系统采用双通道分别接收N_2和O_2对紫外266 nm激光的拉曼散射光,通过拉曼差分法反演大气中O_3浓度。分析了激光雷达系统噪声的来源,对双通道滤光片提出了相应的要求;分析了大气中污染物SO_2,NO_2在紫外波段的吸收特性对拉曼差分法测量O_3的影响及造成的相对误差;利用差分激光雷达AML-2测得的O_3数据模拟了拉曼差分激光雷达系统N_2与O_2的拉曼信号,从而证实了该方法探测对流层底部大气臭氧含量垂直分布的可行性。     

动态模板匹配算法对运动目标进行自动锁定跟踪的研究

模板匹配技术在目标识别跟踪领域得到了广泛应用,它利用已知图像作为模板,在未知图像中移动模板,求图像与模板的相似度,找到相似度最大的点即为匹配成功。针对导弹跟踪锁定目标过程,提出一种动态模板匹配算法,以期达到实时处理的效果,实现对目标的锁定。通过实验仿真显示,该算法是切实可行的。     

基于区域特征合并的分水岭图像分割

传统分水岭变换图像分割方法容易造成过度分割,不利于后期的图像分析与处理。采用一种分水岭变换结合区域特征合并的方法,首先将原始图像进行形态学变换,获取梯度图像;再进行分水岭变换,并将运算后的结果进行基于区域纹理、灰度一致性及区域平滑性等特征的区域合并;最终获取分割结果。实验结果表明,与传统分水岭变换方法相比,该方法能够有效降低因噪声、明暗纹理产生的过分割现象,方法可行、有效。     

基于重叠变换的CDMA Overlay系统窄带干扰抑制

研究了如何利用既有快速实现算法,又有良好滤波性能的重叠变换来分辨并抑制扩增信号中的窄带干扰。首先分析了重叠变换的工作原理,然后在此基础上设计基于重叠变换的窄带干扰抑制接收机,最后对该收机在CD－MA Overlay系统中抑制干扰的性能进行了仿真分析。     

基于漏区边界曲率分析的射频RESURF LDMOS耐压与导通电阻优化

分析了漏区边界曲率半径与射频RESURF LDMOS击穿电压的关系,指出漏区边界的弯曲对RESURF技术的效果具有强化作用.理论分析与模拟结果表明,满足RESURF条件时,提高漂移区掺杂浓度或掺杂深度的同时相应减小漏区边界的曲率半径,可以在维持击穿电压不变的前提下,明显降低导通电阻.     

一种适合医学图像分割的改进分水岭算法

对分水岭算法提出两点改进:先对原始图像的高帽和低帽形态作滤波预处理,滤除原始图像中的噪声和非感知信息,保留原始图像的结构信息;再采用修改了标记符的梯度图像进行分水岭分割,整个分割过程无须进行分割后的区域合并处理,降低了分割的复杂性.这种改进的方法不仅很好地抑制过分割现象,还能使医学图像中的病变区域被有效分割出来,该方法还支持任意形状,与新的静态图像压缩标准JPEG2000兼容,效果很好.     

高速集总型双耗尽电吸收调制器的研制

设计并研制了一种新的直脊波导集总型电吸收调制器——集总型双耗尽电吸收调制器（D-EAM）。同时,作为实验对照组,还制备了一种普通有源区结构的电吸收调制器（N—EAM）。两种器件的测试结果对比分析表明,D-EAM的电容明显要小于N—EAM。脊波导长度为250μm,宽度为2．5弘m的D-EAM在－3V偏压下电容为0．225pF,对应的调制带宽估算为28．3GHZ;1550nm输入波长条件下,D-EAM在偏压为－1V至－2V之间调制效率最大,达到10dB／V,而－3V、－6V下的调制深度分别为22dB和26dB,满足40Gbit／s光纤通信要求。     

A smart spectrum utilization approach using multiantenna‐based cognitive relays in cognitive radio network

Efficient spectrum utilization is a promising technique for a prolonged unused radio frequency (RF) spectrum in a wireless network. In this paper, an adaptive spectrum sharing cognitive radio (CR) network has been proposed consisting of a primary user (PU) and secondary user transmitter (SU ? Tx) that communicates with secondary user receiver (SU ? Rx) via multiantenna‐based proactive decode‐and‐forward (DF) relay selection scheme. In our model, strategically an adaptable joint venture on underlay/overlay protocol is defined based on channel occupancy using spectrum sensing technique. Here, secondary transmitters (i.e., source transmitter) continuously sense the PU activities by energy detector and can simultaneously transmit to secondary receivers. Depending on sensing result secondary transmitters automatically switches in underlay mode if PU is active otherwise operates in overlay mode. The advantage of this scheme is that the joint mode of transmission allows the SUs to maximize their transmission rate. The outage performance at SU ? Rx and closed‐form expressions of joint underlay/overlay protocol has been evaluated. The power control policies at different transmitter nodes are taken care of. With the same diversity order, a trade‐off between multiantenna and multirelay is shown. This comparison shows improvement in outage behavior when the count in relays surpasses the number of antennas. Finally, the analytical model of smart efficient spectrum utilization without harming license users in CR is validated by MATLAB simulation.     

A Novel Algorithm of Water Region Detection in SAR Image Based on Bag of Visual Words and Local Pattern Histogram

Water region detection based on SAR images is a difficult problem for its computing complexity.This paper proposes a novel water region detection method in SAR image of complex scenery.The algorithm takes advantages of Bag of visual words (BOV) to precisely describe the homogeneous region in complex scenery.Local pattern histogram (LPH) and single-class Support vector machine (SVM) are adopted to determine the edge information of water region precisely.The feature extraction is calculated block by block,which reduces computing workload and interference from noise.The experiments based on SAR images of real complex scenery show that the proposed method achieves higher accuracy and robustness.     

基于感兴趣区域的HEVC压缩性能优化

根据人类视觉系统(HVS)对纹理复杂及运动区域具有较强感知度的特点,提出了一种基于感兴趣区域的高效率视频编码(HEVC)压缩性能优化算法.首先使用Sobel梯度检测算子和运动矢量分别检测纹理复杂区域和运动区域,把检测到的纹理复杂及运动区域定义为感兴趣区域;再对感兴趣区域分级,通过调整量化参数(QP),优化比特分配.实验结果表明,与HEVC标准算法相比,所提算法码率平均减少了15.29％,时间平均节省了11.38％.