Viscoelastic characterization of moderately concentrated polystyrene solutions by dynamic light scattering

The dynamic light scattering measurements were performed for moderately concentrated entangled solutions of atactic polystyrene in benzene (BZ) at 25.0 °C, in cyclohexane (CH) at 34.5 °C (Θ), and in diethyl malonate (DEM) at 35.0 °C (Θ) to characterize their viscoelastic properties. The results have shown that while the mutual diffusion coefficient D increases in the BZ solutions and decreases in the CH and DEM solutions with increasing polymer mass concentration c, the friction coefficient ζ for the three solutions increases with c showing the same power-law behavior irrespective of the weight-average molecular weight M_w and solvent quality. It has been found that the instantaneous longitudinal modulus L₀ for the CH and DEM solutions increases in proportion to c², obeying the familiar relation for the plateau value (4/3)G_N of the longitudinal stress relaxation modulus, but the L₀ values for these solutions are somewhat smaller than the values predicted from the relation. The terminal relaxation time τ_m for the two Θ solvent systems has been found to follow the power-law τ_m∝c^2.7, showing good correspondence to the relation established by rheological measurements.     

改进Otsu算法的镀锌板表面缺陷检测方法

针对镀锌板在生产工艺和传输过程中对镀锌板表面造成缺陷的问题;文章应用了基于Otsu算法的镀锌板表面缺陷检测系统,由数字光源控制器、高速CCD相机、同步触发器和编码器等硬件设备共同连接组成,采集到镀锌板表面的图像,然后将图像传输给基于Otsu算法的图像处理系统;改进优化了Ostu算法,在一维直方图求解最佳截距阈值,利用该阈值和二维信息完成图像的分割,提高了图像的抗噪能力;使用分块检验所发初步判定镀锌板表面缺陷,再逐个排查确认缺陷区域,对缺陷特征进行分类并保存在缺陷数据库中,同时发出预警;实验结果显示文章研究的检测系统对镀锌板表面缺陷检出率最高可高达98％,检测出缺陷镀锌板的数量最多,系统的检测精度高.     

Visible light localization algorithm based on multi-measurements constraints

In the indoor visible light transmission environment with complex noise, traditional received signal strength indication(RSSI)localization algorithm and imaging localization algorithm are unable to accurately determine the reason of the inaccurate localization model and inadequate constraints of position coordinates. In order to solve the problems, a visible light localization algorithm based on multi-measurements constraints is presented in the paper. The algorithm first constructs a joint localization state space model based on RSSI localization and the imaging localization algorithm. Then, states, measurements and their equations are constructed based on the space model. Finally, the equations are resolved using the unscented Kalman filter(UKF). Compared with RSSI localization and imaging localization, simulation results show that the RMSE of the proposed algorithm could be closer to the Cramer Rao bound. Besides, the localization probability of the proposed algorithm is higher than that of RSSI localization and imaging localization algorithm.     

Low-loss light propagation in the chain of microcavities

According to the focusing property of the photonic nanojet, the coupling characteristics for the chain of microcavities have been studied. Low-loss light propagation in the chain of microcavities is proposed. The influence of different wavelengths on the intensity of the photonic nanojet and the location of the focal spot are given. Intensity distribution and transmission characteristics for the chain of coupled spherical microcavities are analysed. Simulation results and theoretical analysis show that the chain of spherical microcavities has a highly focused beam and low-loss characteristics because of the focusing effect and backscattering enhancement of the photonic nanojet. A low-loss waveguide can be designed by using these properties of the chain of spherical microcavities. Sub-wavelength focusing of the beam, high optical throughput, and broad spectral transmission properties make the chains of microspheres able to be used in a variety of biomedical applications including minimally invasive and ultraprecise laser surgery.     

轻钢构造柱填充墙的抗侧移性能试验分析

在砌筑填充墙中使用轻钢构造柱,符合绿色建筑发展方向,为研究轻钢构造柱填充墙的整体性力学性能,对轻钢构造柱片墙和混凝土构造柱片墙进行试验对比分析。试验表明,在相同外在条件下,轻钢构造柱片墙试验时墙体侧移发展较缓慢,较混凝土构造柱片墙具有较好的力学性能和抗震性能,由此可为轻钢构造柱在工程设计和实际应用中提供一些参考依据。     

日晒牢度的色度学评价方法研究

传统的牢度测试方法一直是人工目测色差,受到环境、光源、工作人员的视力、辨色经验等因素的限制。随着电脑测色配色技术的迅速发展,研究证明使用仪器代替人眼来评价颜色之间的差异是完全可行的。在5级标准的牢度评价中,有关牢度等级和色度值变化规律已经逐步成熟,但8级评价体系的日晒牢度人工评定等级与色度值变化关系还未见报道。为客观评价日晒牢度,通过测定大量已人工评级的日晒试样的色度值,根据所得的色差值,建立了日晒牢度人工评级和计算机测色的色差值关系表。为了检验所建立的色差值与牢度级别的关系表,测定日晒牢度标准色样中各牢度级别对应的色差值,结果表明,在标准色样中,牢度级别对应的色差值基本符合所建立的关系表。这为日晒牢度的色差值评定提供了参考。     

人眼屈光度校正算法的研究现状

人类能够与用户图像界面进行交互是依赖于一个清晰正常的视觉。然而,屈光不正（例如近视、远视、散光等）能使人眼视网膜中所显示的图像质量退化。图像质量的好坏严重影响了我们在军事、医学、娱乐领域所取得的研究成果。目前,对于人眼屈光度校正算法的研究主要有五种方法：1.应用一个维纳滤波的预补偿算法来校正人眼屈光度;2.用一个全变差的方法绘制图像对人眼屈光度进行校正;3.用视觉分析系统来校正人眼屈光度;4.使用多层显示器来校正视觉畸变;5.使用可计算的光场显示器来校正视觉畸变。通过研究这几种算法的优缺点提出现有算法的改进以及新的算法研究。     

卡塞格林式星敏感器杂散光分析

卡塞格林系统是新型星敏感器的光学系统,具有口径大、体积小的优点,但外界杂散光对卡塞格林系统的影响很大。介绍了一种焦距为425mm,口径为102mm的卡塞格林系统,考虑轴外渐晕的影响,给出星敏感器主遮光罩以及主、次遮光罩的设计方法。这种设计方法相比于其他方法更加便捷和精准。并用Tracepro对系统进行杂散光分析。计算得到点源垂直照度透射比（Point Source Transmittance,PST）曲线。分析结果表明,当杂散光入射角大于临界角30°时,PST值小于10-8量级,满足系统使用要求。证明设计方法是可行的。     

基于偏振光检测的溶液浓度测量方法研究

为了克服旋转检偏片法测量旋光性溶液浓度存在的误差大、精度低等不足,提出了一种基于旋转波片的偏振光检测溶液浓度的测量方法。采用PIN光电二极管对带有溶液浓度信息的偏振光信号进行探测,经过光电变换后利用信号调理电路实现信号处理、采集等,并将数据通过串口传送到上位机,利用LabVIEW程序进行数据处理与显示。实验结果表明,基于旋转波片的偏振光检测溶液浓度的测量方法测量精度为0.6%。该测量方法能够减小测量误差、提高测量精度,并且用户界面友好、结果显示直观。     

虾蛄眼识别偏振光机理的分析

虾蛄眼最显著的特点是它可以识别偏振光,这种特性对偏振探测和目标识别的研究有很大的帮助。通过实验对虾蛄眼的生物特征参数进行了测试,获得微绒毛尺寸,本文主要分析了虾蛄眼光感细胞微绒毛之间的关系、微绒毛的排列方向以及微绒毛内壁发色团的特性,即平行排列在微绒毛内壁的发色团具有二向色性,并且研究该特性与圆偏振光探测机理的关系,从而为虾蛄眼圆偏振光识别机理的研究奠定了基础。