蒸发器支撑板板孔精密测量系统

建立了蒸发器支撑板板孔精密测量系统,并提出了基于边缘约束条件的轮廓参量测量方法.首先采用图像处理技术将待测目标转化为二维离散坐标点,计算其最小外接矩形并对轮廓进行预定位;然后将轮廓分割成相互重合的扩展邻域轮廓,建立以曲率角为原则的边缘约束算法对各轮廓段精确定界,实现对轮廓参量的精密测量.实验和误差分析表明,该系统测量准确度优于0.02mm,对具有复杂轮廓的零件参量测量有参考价值.     

Electrode “edge effects” analyzed by the Green function method

An exact method based on Green's equation is used to find the diffusion-controlled faradaic current for certain electrode geometries that incorporate edges and vertices. Thereby the magnitudes of the time-independent current density associated with angled electrode/electrode and electrode/insulator junctions are calculated. As well, the square-root-of-time-dependent currents associated with vertices, receive attention. These terms extend to longer times, the Cottrell formulation appropriate for short times. Though most of the problems solved here have been tackled previously, the novel Green function approach is shown to be straightforward and intuitive.     

Solution Crystallization Behavior of Linear and Star-shaped Poly(ethylene glycol)-b-Poly(ε-caprolactone) Block Copolymers简

Lamellar crystals of diblock, triblock and four-arm poly（ethylene glycol）-b-poly（ε-caprolactone） （PEG-b-PCL） crystalline-crystalline copolymers were successfully obtained from their solution. Morphology and structure of lamellar crystals of crystalline-crystalline copotymers were investigated using tapping-mode atomic force microscopy （AFM） and selected area electron diffraction （SAED）. All of these samples showed the truncated-lozenge multilayer basal shapes with central screw dislocation or central stack, which were all obtained simultaneously from the oil bath. The diffraction pattern of PEG block lamellar crystal is attributed to the （120） diffracting planes and the pattern of PCL block lamellar crystal is attributed to the （1 I0） diffracting planes and （200） diffracting planes according to the SAED results. Four （110） crystal growth planes and two （200） crystal growth planes are discovered for the PCL blocks, but the （120） crystal growth planes of PEG blocks are hided in the figure of AFM. The crystalline structure of the four-arm copolymers （FA） is more disorder and confused than that of the diblock （DI） copolymer and the striated fold surface structures of lamellar crystals of four-arm copolymers （FA） are smoother than these of linear analogues, owing to the confused crystallization of blocks caused by the mutual restriction of blocks and the hindrance of the dendritic cores. In addition, the aspect ratio of FA is greater than that of the others. It is hypothesized that there are two reasons for the change of aspect ratios. First, the （200） diffracting planes of PCL crystals grew slowly compared to their （110） diffracting planes because of difference in the energy barrier. Secondly, edge dislocations on the （200） diffracting planes are also responsible for the variation of the aspect ratio. Consequently, the crystalline defects are augmented by the competing blocks crystallized simultaneously and the hindrance of the dendritic cores.     

Field Desorption Mass Spectrometry of Standard Organophosphorus Pesticides and Their Identification in Waste Water

The characteristic behaviour of four groups of commonly used organophosphorus pesticides such as phosphates, phosphorothionates, phosphorothiolates and phosphorodithioates has been investigated by field desorption mass spectrometry. Their spectra show molecular ions of high abundance and characteristic fragmentation patterns. The phosphates and phosphorothionates usually show the α-cleavage with respect to the P-atom with and without proton transfer. In contrast, the phosphorothiolates and phosphorodithioates usually show the β-cleavage from the P-atom. The fragments with the charge retention on the phosphorus moiety were also observed in the field desorption mass spectra, although their abundances were often relatively low.

The analyses of standard mixtures as well as some waste water samples indicate that field desorption mass spectrometry is suitable for the identification of organophosphorus pesticides at nanogram level in mixtures and environmental samples without preliminary separation and purification.     

高多层Mini型金属化边PCB制作技术研究

多层Mini型金属化边PCB作为印制电路板的一种特殊产品,在电子元器件向轻、薄、短、小的发展要求下,而得到广泛应用。然而此类PCB在实际生产过程中仍有一些与普通PCB板制作的不同点。Mini型金属化边,顾名思义,就是指成品尺寸在30 mm×30 mm以下,且板边有小于6 mm长度的电镀金属化边,并且整个PCB的成型尺寸也十分小,没有定位孔,制作难高十分高,需要就包括制前设计、过程控制、成品铣板和成品尺寸测量等问题进行综合考虑。针对多层金属化边Mini型PCB的特征,从设计方法进行了详述,并对其制作技术难点分别提出了解决方案。可帮助读者清晰的了解此类产品的特性和制作方法,以为业者提供一些可以借鉴的行业经验。     

边缘图像滤波算法

图像经过边缘提取之后常会带有各种噪声,提取的边缘还不能满足需要,讨论了对边缘图像的滤波算法,先对边缘的图像进行闭运算,再进行区域标记。实验结果表明,该算法对提高边缘图像的质量是非常有效的。     

Adaptive–interpolative binarization with stroke preservation for restoration of faint characters in degraded documents

A novel technique for binarization with stroke preservation of faint characters in degraded documents is proposed. It works in a multi-scale framework with an adaptive–interpolative thresholding technique. Instead of computing a global threshold value, it computes the local threshold values for a small set of grid points by observing the intensity pattern of the pixels lying in the concerned grid cells. Estimated thresholds are used, in turn, to compute the threshold values of all the remaining pixels using a fast-yet-efficient interpolation procedure. To handle noises in degraded images, this grid-based adaptive thresholding is applied in successively reducing scales to obtain the near-optimal binarization as a set of connected components. After a post-processing meant for stroke preservation with these connected components, we get the final output. Exhaustive experimentation and comparison with other existing methods have been successfully carried out with benchmark datasets and also with our own datasets.     

LDPC码的全并行概率译码

针对LDPC码和积译码算法运算量大、电路实现复杂度高,介绍一种新的LDPC译码实现结构——概率译码器。该结构结合随机运算思想,运算量大幅降低,电路布线实现压力减小,吞吐量显著提高,针对该算法的内部路由可能出现的死锁问题引入了边存储器（EM,Edge Memory）概念。在AWGN信道下,对上述方法进行了仿真验证,给出了新方案和旧算法的性能分析比较,结果显示该算法的性能相比传统LDPC译码器有近0.2 dB的性能损失,但译码复杂度得到显著降低。