Rate Control Strategy Based on the Distributed Character of DCT Coefficients

根据缓存器的状态和信道速率为待编码帧在图像层上预分配目的视频编码比特数 ,使用DCT系数分布特性来表征图像特性 ,继而为帧内每一具体宏块选定最佳量化因子 ,提出了基于DCT系数分布特性的码率控制策略 .并分析了算法的复杂度 ,提出了改进策略 .模拟实验表明 ,该码率控制策略能有效地减少、避免缓存器出现上、下溢的情况 ,而输出码率趋于稳定 .提高了重建图像的信噪比 ,并且在视频图像质量没有明显失真的前提下 ,改进了计算复杂度 .Rate control strategy based on the distributed character of DCT coefficients is proposed , we allocates the target number of bits firstly on picture layer based on the status of the buffer and the channel rate, and then denotes the characteristics of the picture by the distributed characteristics of the DCT coefficients and select a best quantized parameter for every macroblock in a frame. The complexity of the algorithm is analyzed and an improved method is proposed. The experiment shows that this rate control strategy can effectively reduce and avoid the overflow and underflow of the encoder buffer, and the output bit rates tend to stabilization. The PSNR of the reconstructed picture is raised, and the complexity of the algorithm is improved with no visible distortion in video image.安徽省教委自然科学基金资助项目 (99j10 0 18

DNA修饰电极的研究——Ⅶ.共价键合和吸附DNA-SAM/Au修饰电极的制备及表征

采用先通过 2 ,2′ 二硫二乙醇自组装得到自组装单分子层 (SAM) ,再在SAM上共价键合和吸附固定dnA的方法制备了两类dnA修饰电极 ,并对得到的dnA修饰电极进行了电化学和谱学表征 .结果表明该方法是可行的 ,也是较为理想的在电极表面固定dnA的方法 .国家自然科学基金!(批准号:39370213;39770220;29773034);厦门大学固体表面物理化学国家重点实验室基金;湖北省自然科

包层结构对光子晶体光纤光栅反射谱的影响

利用RSoft软件对包层空气孔为正六边形对称结构的光子晶体光纤的模场进行了分析,并使用模式耦合理论和传输矩阵法对光子晶体光纤光栅（PCFG）特性进行了计算和仿真,对比了不同包层结构和纤芯尺寸的PCFG反射谱之间的差异。仿真结果显示,占空比和纤芯尺寸的大小可影响谐振峰的数量和谐振波长值的大小

新型太赫兹波塑料光子晶体光纤的色散特性

文章提出一种新型低损耗太赫兹波塑料光子晶体光纤（THz-PPCF）结构,其包层是由两种直径不同的空气孔周期性排列而成。利用时域有限差分法（FDTD）对其色散特性进行了分析。结果表明,通过调节包层中两种空气孔的直径以及晶格常数,可以得到低损耗、超平坦趋于零色散的太赫兹波塑料光子晶体光纤

Extending Atomic-resolution Electrochemical Scanning Tunneling Microscopy Studies to Polycrystalline Electrode SurFaces

Electrochemical Scanning TUnneling Microscopy (ECSTM) has been extended to characterizc polycrystalline silver electrode surFaces in iodide solution.Potential-dependcnt ordered and disordered structures of the silver electrode as well as the iodine adsorption layer have been obscrved to coexist on polycrystalline silver electrode surFaces, For the First time.A very special column arrangement of the iodine adsorption layer, similar to the so called "ndssing row" type of structure has been obseryed.Some columns of the iodine adsorption layer roll over From one place to another along with the time and changing potential.A proposed model has been given to better describe the structure.The highly corrugated and loose surFace structure of the polycrystalline surFace are responsible For this special phenomenon.固体表面物理化学国家重点实验室和国家自然科学基

Face Recognition Based on Selective Attention and Parcone Model

为了克服以往人脸识别方法因特征提取带来的信息损失与不确定性因素,提出了一种应用于复杂场景中人脸识别方法,这种方法不需要进行特征提取.先对整幅图像使用选择性注意方法,在得到的显著区域中利用AdAbOOST算法进行人脸搜索与定位,最后将可能包含人脸区域的所有像素全部输入训练好的部分连接神经网络(PArCOnE)模型进行识别.整个识别过程全部自动完成,不需人工干预,也不必对图像进行预处理.通过利用MIT-CbCl人脸数据库和自建图像库进行的仿真实验表明,该人脸识别方法在复杂背景中具有较高的识别率,可适用于其他类型的目标识别.In order to overcome the loss of information and uncertainties in the previous methods of face recognition,this paper proposes a face recognition method in complex scene,and it does not need feature extraction.The method first used selective attention in the whole image,and then used Adaboost to search and locate the faces in the salience region.Finally,it put all pixels of the region which may contain face into trained partially connected neural evolutionary(Parcone) module to recognize.All of the recognition process was automatically and there is no need for image preprocessing.The experiments use MIT-CBCL face database and self-build image database,and the results show that this face recognition method has good recognition rate in complex background.The method in this paper can be applied to other types of target recognition.福建省自然科学基金(2009J01305);厦门大学“985工程”二期项目资

隧道电子和局域场对固液界面纳米区域反应的影响——控电位下的Si(111)表面的STM诱导纳米刻蚀

隧道电子和局域场对固液界面纳米区域反应的影响①——控电位下的Ｓｉ（１１１）表面的ＳＴＭ诱导纳米刻蚀谢兆雄＊蔡雄伟施财辉毛秉伟田昭武（厦门大学固体表面物理化学国家重点实验室物理化学研究所化学系厦门３６１００５）扫描隧道显微技术（ＳＴＭ）目前已成为纳米加..

基于PolSK调制格式的FWM型全光比较器

文章提出了一种利用偏振移位键控（PolSK）信号光,基于半导体光放大器（SOA）中的四波混频（FWM）效应的超快全光比较器方案。该方案由于采用了功率恒定的PolSK信号光,可以消除SOA中的码型效应。通过数值模拟,研究了两输入信号光功率、SOA注入电流以及有源区长度对超快全光比较器输出特性的影响

Gold Electrodeposition on Microelectrodes

本工作利用循环伏安法和阶跃电位法研究在ＡｕＣｌ３的酸性溶液中金在玻碳和铂微电极上的电沉积行为．结果表明，金在微电极上成核所需的过电位较高，但成核几率也高，在所研究的微电极尺寸范围内，金可形成大量的临界单核，且核的生长速率很快．铂微电极上金电沉积的Ⅰ－ｔ曲线符合连续成核的模式．玻碳微电极的沉积历史对金的电沉积行为的影响较大，可以加速金的成核和生长，而铂却没有这种影响．The initial stage electrodeposition behaviors of gold onto glassy carbon and platinum microelectrodes are studied in an acid solution containing AuCl_3using cyclic voltammetry and potential step techniques. The results suggest that gold nucleation on microelectrodes requires a higher driving force with high probability. Within the range of the microelectrode dimension that have been used in the present work, large amount of gold nucleus could be formed at short time scale at overpotentials higher than a threshole value. The It curves from the platinum microelectrode are in consistence with the continuous nucleation model. It has been found that the deosition history of the glassy carbon microelectrode substrate has strong influences on subsequent electrodeposition behavior while the platinum microelectrode does not show such effects.作者联系地址：江西师范大学化学系,厦门大学固体表面物理化学国家重点实验室Author's Address: Dept. of Chem., Jiangxi Normal Univ., Nanchang 330027Shi Caihui Li Xiaoqni Mao Beigwei*State Kay Lab. for Phy. Chem. of Solid Suface, Inst. of Phy. Chem., Chem. Dept., Xiamen Univ., Xiamen 36100