面向图像局部重建的梯度分析

在基于场方向导数的图像局部区域重建过程中,梯度计算对图像边缘的重建效果有很大影响。分析选择单向计算梯度分量的必要性,提出梯度计算的就近原则,对参与梯度分量单向计算的相邻点设置优先级,将缺损点与已知点之间的边缘特征反映在已知点的梯度中,进而影响重建过程,从而实现对图像中边缘特征的重建。实验结果表明,采用该梯度计算模式能有效改善对图像边缘特征的重建效果。     

基于MMFD-FCM的退化状态识别方法及其应用研究

为了有效地对机械设备运行状态进行监测,进而对其性能退化状态进行识别,提出一种基于形态多重分形维数(MMFD)与模糊C均值聚类(FCM)的性能退化状态识别方法;该方法首先计算机械设备振动信号的形态多重分形维数,以此作为性能退化特征指标;该特征指标能够有效反映峰值在振动信号中概率分布的不均匀程度,从而定量描述振动信号的性能退化状态,并且与多重形态分形维数相比,利用数学形态学计算的MMFD精度更高,计算速度更快;在此基础上,鉴于不同退化状态之间的模糊性,针对性地采用模糊C均值聚类方法对特征指标进行模糊聚类,从而有效识别性能退化状态;将该方法应用于滚动轴承全寿命周期振动信号中,分析结果验证了该方法的有效性。     

Investigation on formaldehyde gas sensor with ZnO thick film prepared through microwave heating method

ZnO nanopowders were prepared through microwave heating method. ZnO thick film sensors were fabricated by using ZnO nanopowders as sensing materials. The phase composition and morphology of the material particles were characterized by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The gas-sensing properties of the sensors based on ZnO nano-materials were investigated. It was found that the sensor based on ZnO nano-materials (low power, 10× 10 min) exhibited very high responses to benzene and toluene when operating at 440 and 370 °C, respectively; but the sensor based on ZnO (low power, 10× 10 min) showed very low responses to benzene and toluene when operating at 205–215 °C. The sensor based on ZnO (low power, 10× 10 min) showed high response and good selectivity to dilute formaldehyde when operating at 210 °C; especially, the response to 0.001 ppm HCHO attained 7.4 when operating at 210 °C.     

基于故障树的智能电能表可靠性分析

智能电能表系统复杂且广泛运用于日常生活,智能电能表可靠性的提升对于整个电力部门的正常运行具有重要意义。提出了基于故障树的智能电能表可靠性分摊算法,利用可靠性指标对系统可靠性进行分析。该算法包括智能电能表故障树的建立,可靠性分摊算法在故障树最小割集中的结合应用,提出元件可靠性指标进行智能电能表元件可靠性评估。根据智能电能表的结构特点、各功能作用进行定性分析,建立完整的智能电能表故障树。由可靠性指标进行智能电能表元件故障追踪,确定对电能表故障影响的关键元件,从而通过相应措施进行故障预防提高智能电能表可靠性。通过对智能电能表可靠性指标的评定证明本算法对系统可靠性指标的改进,有效提高分析系统可靠性。     

Investigation of CMP of Ni in the Preparation Process of Micro-Electro-Mechanical System Devices

利用自制的抛光液对高纯镍片进行化学机械抛光,研究化学机械抛光过程中抛光压力、pH值、H2O2浓度、络合剂种类及其浓度、SiO2浓度等参数对抛光速率的影响。结果表明在抛光压力为13.79kPa、H2O2浓度为0.5%,pH值为3.0,SiO2浓度为0.5%,络合剂EDTA及其浓度为1%时,得到最大抛光速率为312.3nm/min;在抛光压力为13.79kPa、pH值为4.0、SiO2浓度为1%、络合剂EDTA为1%、H2O2浓度为1%条件下抛光得到的镍片表面质量较好,表面粗糙度Ra达到5nm。并利用电化学手段研究了镍片在抛光液中的溶解与钝化行为。     

Preparation and gas-sensing properties of SnO<Subscript>2</Subscript>/graphene quantum dots composites via solvothermal method

SnO₂/graphene quantum dots (GQDs) nano-composites were prepared via solvothermal method (160 °C, 10 h), in which graphene quantum dots were synthesized from graphene oxide by one-step solvothermal method. The nano-composites were characterized by means of HRTEM, XRD, SEM, FTIR, XPS and N₂ adsorption–desorption, respectively. The sensor devices were fabricated using SnO₂/GQDs nano-composites as sensing materials. The effect of the GQDs content on the gas-sensing responses and the gas-sensing selectivity was investigated. The experimental results showed that the sensor based on SnO₂/GQDs nano-composite (S-2) exhibited good response and good selectivity to acetone vapor. When operating at 275 °C, the responses of the sensor based on SnO₂/GQDs nano-composite (S-2) to 1000 and 0.1 ppm acetone reached 120.6 and 1.3, respectively; the response time and the recovery time for 1000 ppm acetone were 17 and 13 s, respectively.     

锇在甲酸体系抛光液中化学机械抛光研究

基于金属锇有可能成为大规模集成电路铜互连扩散阻挡层新材料,利用自制的甲酸(HCOOH)体系抛光液对金属锇进行了化学机械抛光研究,利用原子力显微镜(AFM)观察抛光后锇的表面形貌。采用电化学分析方法研究双氧水(H2O2)、HCOOH和苯丙三氮唑(BTA)对样品腐蚀效果的影响。结果表明:当抛光液中仅含H2O2时,金属锇表面腐蚀不明显;而在H2O2-HCOOH体系中,H2O2浓度的增加可使金属锇表面的腐蚀速度明显加快,但不利于金属锇表面钝化膜的形成;缓蚀剂BTA的加入促进了金属锇表面钝化膜的生成,降低了抛光速率,但同时提高了金属锇的表面质量,表面粗糙度Ra由8.0 nm降低到4.2 nm。     

Acetic acid gas sensors based on Ni2+ doped ZnO nanorods prepared by using the solvothermal method

Ni²⁺-doped ZnO nanorods with different doping concentrations are prepared via the solvothermal method. The doped ZnO nanorods are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The amount of Ni²⁺ ions that enter the lattice of ZnO increases with increasing the Ni²⁺/Zn²⁺ molar ratio when the molar ratio of Ni²⁺/Zn²⁺ in the starting solution is lower than 3% and does not change obviously if the mole ratio of Ni²⁺/Zn²⁺ in the starting solution is in the range of 3-10 mol%. The effect of Ni²⁺ doping on the gas-sensing properties is investigated. The results reveal that the amount of Ni²⁺ has a great influence on the response (R_a/R_g) and the gas-sensing selectivity. The sensor based on 1 mol % Ni²⁺ doped ZnO nanorods (120 ℃, 10 h) exhibits a high response to acetic acid vapor, in particular, the responses to 0.001 ppm and 0.01 ppm acetic acid vapor reach 1.6 and 2, respectively. The response time and the recovery time for 0.001 ppm acetic acid are only 4 s and 27 s, respectively.     

光接入网在惠州本地电信网中的应用

本文介绍了惠州市光接入网的建设现状 ,并讨论了目前存在的一些问题以及采取的原则与策略。     

基于小波分析和克隆选择算法的模拟电路故障诊断

提出一种基于人工免疫系统的模拟电路故障诊断新方法.该方法首先对电路输出节点的电压信号进行小波分解,提取各频段的能量作为故障样本;然后利用人工免疫算法对每类故障的故障样本进行自学习,得到该类故障的最优聚类中心;最后计算故障样本和学习得到的聚类中心的距离对电路故障样本进行分类,从而实现故障元件定位.计算机仿真实验结果表明,该方法对容差模拟电路故障定位具有较高的准确率.