颈动脉B超估计血管壁搏动位移的干扰抑制

超声检测时,由于测量者把握探头的不稳定、受试者的呼吸运动等造成的干扰,将对通过B超图像进行斑点跟踪提取到的动脉壁位移的精度造成影响.为此,本文提出基于B超序列相位图像的全局刚性特征进行配准消除干扰.相位特征通过对B超图像进行Riesz变换,再采用高斯差分法提取得到.为了更快地完成寻优,减少配准误差,采用了基于位置加权的主轴质心法与互信息相结合的分阶段的配准方法.结果表明,与直接对B超或相位图采用斑点跟踪的方法相比,该方法有效去除了干扰,管壁位移提取的精度有显著提高.本文方法还可用于心脑等医学图像的配准.     

滞止火焰场中TiO2颗粒的烧结特征研究

由于对颗粒粒径分布和晶型的显著影响,纳米TiO2颗粒的烧结特征在滞止火焰合成工艺中至关重要.本文通过插入式热泳采样和对合成时间的调控,对颗粒在火焰中和滞止板上的烧结特征进行了研究,进而利用颗粒群平衡模型结合表面积线性衰减理论,对火焰中颗粒的团聚和滞止板上沉积颗粒的粒径分布进行了理论分析预测,其结果与实验结果相吻合.     

Enhancement of water permeation across nanochannels by partial charges mimicked from biological channels

In biological water channel aquaporins （AQPs）, it is believed that the bipolar orientation of the single-file water molecules inside the channel blocks proton permeation but not water transport. In this paper, the water permeation and particularly the water-selective behaviour across a single-walled carbon nanotube （SWNT） with two partial charges adjacent to the wall of the SWNT are studied by molecular dynamics simulations, in which the distance between the two partial charges is varied from 0.14 nm to 0.5 nm and the charges each have a quantity of 0.5 e. The two partial charges are used to mimic the charge distribution of the conserved non-pseudoautosomal （NPA） （asparagine/proline/alanine） regions in AQPs. Compared with across the nanochannel in a system with one ＋1 ε charge, the water permeation across the nanochannel is greatly enhanced in a system with two ＋0.5 e charges when charges are close to the nanotube, i.e. the two partial charges permit more rapid water diffusion and maintain better bipolar order along the water file when the distance between the two charges and the wall of SWNT is smaller than about 0.05 nm. The bipolar orientation of the single-file water molecules is crucial for the exclusion of proton transfer. These findings may serve as guidelines for the future nanodevices by using charges to transport water and have biological implications because membrane water channels share a similar single-file water chain and positive charged region at centre and provide an insight into why two residues are necessitated in the central region of water channel protein.     

基于晶图IS1521芯片的DVB—C机顶盘系统方案

本文介绍采用国产芯片实现DVB—C有线机顶盒的解决方案。在此方案中，解码的核心芯片采用杭州晶图微芯技术有限公司的IS1521。IS1521是由杭州晶图微芯技术有限公司（ImageSilicon^TM）自主研发的一款针对数字电视机顶盒DVB—S／C／T的大规模系统级（SoC）数字电视信源解码芯片。     

多运动平台多传感器机动目标自适应跟踪

针对多运动平台多传感器背景下的机动目标跟踪问题,提出了模糊自适应无迹卡尔曼滤波(FUKF)算法,基于良好机动性描述的"当前统计"模型和良好非线性滤波能力的UKF(Unscented Kalman Filter),利用模糊推理技术实时自适应地调整系统噪声协方差矩阵,来提高对目标机动性的理解能力和跟踪精度.仿真实验表明该算法的有效性.     

Photoluminescence Property of Co3O4 Nanowires

Co3O4 nanowire arrays are fabricated by electrodeposition with following heat-treatment in atmosphere ambient. Photoluminescence is investigated at 295K. In the experiment, when increasing the excitation light wavelength from 260 nm to 360 nm, two kinds of emissions corresponding to the increasing excitation light wavelength are observed. One of them alters the excited emission position, another keeps its emission position. The distinct behaviour of excited emissions related to the increasing excitation wavelength indicates that the mechanism of them must be different. According to the experimental comparison and first-principle calculation, the two kinds of emissions are discussed.     

Mn0.1Ti0.9O2-δ稀磁半导体薄膜的MBE生长及表征

采用OPA-MBE方法在SrTiO3(STO)衬底上成功制备了Mn0.1Ti0.9O2-δ(MTO)稀磁半导体薄膜.利用X射线衍射仪、X射线光电子能谱仪、紫外可见光分度计以及直流四探针测试仪研究了薄膜的晶体结构、化学组成、光吸收和电荷输运性质.MTO薄膜具有锐钛矿和金红石的混合相,光吸收带边界发生"红移",电荷输运性质明显提高,室温环境下电阻率仅为37.5Ω·m.     

横向激励CO2激光器内腔等离子体开关

横向激励CO2激光器由于输出能量和峰值功率高，所以得到了广泛应用。然而这种激光器的固有脉冲形状在一些特殊场合往往不理想，在光雷达和非线性现象研究等应用中，效果不佳。这里报道的内腔等离子体开关，装置结构简单、牢固，尤其适用于大孔径焦耳级激光器。开关很容易插到标准激光谐振腔里面，无需任何附加光学元件或内光束聚焦。     

激光电弧复合焊接AZ31B镁合金

采用激光束与电弧复合焊接AZ31B镁合金，研究了这种复合热源对焊接熔深、表面成型的影响，探索了激光-电弧不同复合方式对焊接过程中电弧稳定性的影响。结果表明，激光束与焊接电弧共同组成的复合热源在正向焊接镁合金时形成的焊接熔深，比单独采用钨极氩弧焊(TIG)焊接增加了1倍左右，同时复合热源焊接电弧稳定性也较钨极氩弧焊接提高了1倍以上，是一种理想的镁合金焊接方法；而当激光-电弧复合热源反向焊接时，电弧稳定性较正向焊接进一步增大。对复合热源的电弧稳定性和激光吸引电弧的现象以及熔深增加的机理进行了讨论。