基于数据挖掘的刮刀压力对印刷质量影响分析

针对电子产品制造的锡膏印刷过程参数众多、交互作用复杂的问题，文中利用神经网络算法建立一种短时印刷质量预测模型。对基于刮刀压力设置值和基于刮刀压力实际值的模型精度进行比较，结果表明，基于实际值的模型误差为2.12%，基于设置值的模型误差为5.42%，基于实际值模型的精度优于基于设置值的模型。进一步分析具体数据发现，基于刮刀压力设置值模型误差较大的原因是：不同设置值对应的实际值波动较大，且设置粒度分辨力无法完全区分不同设置值对应的实际值。由于设置值和实际值存在较大差异，印刷时钢网承受的压力与预设的压力值范围不同，导致实际的下锡量与参数调整时预想不同，所以刮刀压力设置值的印刷质量预测模型精度较差。     

电力营销报装模式新变革

随着经济的发展与高新科技的进步,电力系统部门也在不断地进行变化,在电力营销报装模式上进行变革是对电力系统整体的一个技能提高,电力系统的营销报装模式的新变革可以使一些高压报装的模式变得较为简单,可以适应电力系统的营销概念,本文从电力营销报装模式的新变革为重点,展开对报装模式的论述,以期对电力营销报装模式的新变革能起到推动作用。     

功能化离子液体[bmim]OTs催化乙酰化反应

以离子液体1-丁基-3-甲基咪唑四氟硼酸盐([bmim]BF4)为溶剂,对甲基苯磺酸根(OTs-)为阴离子的功能化离子液体[bmim]OTs为催化剂进行苯甲醇的乙酰化反应.结果表明,该体系循环使用10次后仍能保持良好的催化活性和稳定性,并对各种(伯、仲、叔)醇类、酚类和胺类化合物的乙酰化反应表现出良好的普适性.核磁共振波谱(13C NMR)分析结果表明,具有亲核性的[bmim]OTs和酰化试剂乙酸酐(Ac2O)形成的活性中间体AcOTs,是催化反应的活性物种.     

改进格雷码条纹投影三维测量方法

传统的格雷码加相移法已经广泛应用于三维测量,但是相位解包裹一般需要投影多幅格雷码条纹,如何实现快速、准确的三维测量仍具有一定挑战性。提出了一种基于几何约束的改进格雷码条纹投影三维测量方法,可以有效减少格雷码条纹的数量。为了实现高速条纹投影,使用二值抖动技术将8位正弦相移条纹转换为1位二值图像。总共使用六幅条纹图像,其中三幅相移条纹用于计算截断相位,三幅格雷码条纹用于对截断相位进行初步展开获得伪展开相位,最后利用几何约束对伪展开相位进行解包裹获得绝对相位。实验结果表明,所提方法可以有效地重建被测物体的三维形貌。     

城轨列车网络控制系统方案设计简析

为满足轨道车辆系统部件的稳定性、安全性,确保车辆长期良好的运行状态,需对列车网络控制系统方案进行设计优化,通过软件指导帮助用户对列车运行及事件情况进行分析,对列车进行调试与维护。     

Double-rod metasurface for mid-infrared polarization conversion

Resonant responses of metasurface enable effective control over the polarization properties of lights. In this paper,we demonstrate a double-rod metasurface for broadband polarization conversion in the mid-infrared region. The metasurface consists of a metallic double-rod array separated from a reflecting ground plane by a film of zinc selenide. By superimposing three localized resonances, cross polarization conversion is achieved over a bandwidth of 16.9 THz around the central frequency at 34.6 THz with conversion efficiency exceeding 70%. The polarization conversion performance is in qualitative agreement with simulation. The surface current distributions and electric field profiles of the resonant modes are discussed to analyze the underlying physical mechanism. Our demonstrated broadband polarization conversion has potential applications in the area of mid-infrared spectroscopy, communication, and sensing.     

Boundary segmentation based on modified random walks for vascular Doppler optical coherence tomography images

Vascular Doppler optical coherence tomography(DOCT) images with weak boundaries are usually difficult for most algorithms to segment. We propose a modified random walk(MRW) algorithm with a novel regularization for the segmentation of DOCT vessel images. Based on MRW, we perform automatic boundary detection of the vascular wall from intensity images and boundary extraction of the blood flowing region from Doppler phase images. Dice, sensitivity, and specificity coefficients were adopted to verify the segmentation performance. The experimental study on DOCT images of the mouse femoral artery showed the effectiveness of our proposed method, yielding three-dimensional visualization and quantitative evaluation of the vessel.     

一种基于用户行为习惯的主机安全性检测方法

文中提出了一种基于用户行为习惯的主机安全性检测方法.通过建立一种以攻击树root代表主机的拓展攻击树模型来研究用户的行为习惯对主机的影响,并以此来描述主机安全性.该方法实现了对不同用户主机安全性的智能评估,为主机安全性检测提供了一种新方向.     

Syntheses,Crystal Structures and Fluorescence Properties of Four Coordination Polymers Based on Enantiomeric 2-(4-Carboxyphenyl)-4,5-dihydrothiazole-4-carboxylic Acid Ligands

A pair of enatiomerically pure ligands,(R-)/(S-)2-(4-carboxyphenyl)-4,5-dihydrothiazole-4-carboxylic acid(H2L^R & H2L^S), have been synthesized by the reactions of 4-cyanobenzoic acid with L-and D-cysteine, respectively. Four coordination polymers have been prepared from the ligands and structurally determined by single-crystal X-ray diffraction analysis. Complexes 1 R and 1 S([NiL(Py)(H2 O)]×H2 O, for 1 R, L =(L^R)^2-;for 1 S, L =(L^S)^2-) exhibit chiral helical one-dimensional chains, and complexes 2 R and 2 S({[ZnL2(H2 O)3]×CH3 CN}n, for 2 R L =(L^R)^2-, for 2 S L =(LS)^2-) are two-dimensional sheets. Luminescent and chir-optical properties have been investigated and compared with the free ligands. The complexes have blue-shift in luminescence spectrum compared with the free ligands.     

基于柔性玻璃衬底ZnO∶B薄膜的非晶硅太阳能电池的制备及其光电性能研究

采用低压化学气相沉积法(LPCVD)在大面积(40 cm ×40 cm)超薄柔性玻璃和硬质玻璃衬底上分别制备了B掺杂的ZnO(BZO)透明导电薄膜及非晶硅薄膜太阳能电池,对比了两种衬底上BZO薄膜的形貌、光学和导电性能及其非晶硅薄膜电池的性能.结果表明,在相同LPCVD工艺下,超薄柔性玻璃衬底上BZO薄膜的生长速率相对减小;当生长相同厚度BZO薄膜时,超薄柔性玻璃衬底的透光率相对于硬质玻璃衬底提高约2;,同时并具有相同的导电能力.在柔性玻璃衬底上制备的非晶硅薄膜电池的初始和稳定转化效率也相对提高,分别达到9.16;和7.82;.