Aspects of Ozone Generation from Air

In many fields of industrial application the usage of ozone is a question of economics. In order to improve the efficiency of especially air-fed ozone generators, fundamental research work on modelling of microdischarges, the chemical reaction scheme, and extensive experimental investigations have been undertaken. By proper choice of the operation conditions like pressure, gap width, and cooling conditions, the efficiency can be improved considerably. The reaction temperature in the process volume and the concentration of nitrogen oxides are the main factors influencing the ozone yield.     

龙门式电火花线切割机床间隙状态控制系统设计

间隙状态控制系统是电火花线切割机床的重要组成部分.基于龙门式电火花线切割机床的结构特点,研制了一种全新的间隙状态模糊控制系统.实际使用效果表明,此系统性能良好.     

锯齿型径向迷宫密封的实验研究

采用轴对称多齿迷宫密封模型,实验研究了锯齿型径向迷宫密封的密封性能。结果表明,密封性能并非随着齿插入长度的增加而单调增加,而是存在一个最佳的齿插入长度。     

Airborne discrete-return LIDAR data in the estimation of vertical canopy cover, angular canopy closure and leaf area index

Remote sensing of forest canopy cover has been widely studied recently, but little attention has been paid to the quality of field validation data. Ecological literature has two different coverage metrics. Vertical canopy cover (VCC) is the vertical projection of tree crowns ignoring within-crown gaps. Angular canopy closure (ACC) is the proportion of covered sky at some angular range around the zenith, and can be measured with a field-of-view instrument, such as a camera. We compared field-measured VCC and ACC at 15° and 75° from the zenith to different LiDAR (Light Detection and Ranging) metrics, using several LiDAR data sets and comprehensive field data. The VCC was estimated to a high precision using a simple proportion of canopy points in first-return data. Confining to a maximum 15° scan zenith angle, the absolute root mean squared error (RMSE) was 3.7-7.0%, with an overestimation of 3.1-4.6%. We showed that grid-based methods are capable of reducing the inherent overestimation of VCC. The low scan angles and low power settings that are typically applied in topographic LiDARs are not suitable for ACC estimation as they measure in wrong geometry and cannot easily detect small within-crown gaps. However, ACC at 0-15° zenith angles could be estimated from LiDAR data with sufficient precision, using also the last returns (RMSE 8.1-11.3%, bias -6.1-+4.6%). The dependency of LiDAR metrics and ACC at 0-75° zenith angles was nonlinear and was modeled from laser pulse proportions with nonlinear regression with a best-case standard error of 4.1%. We also estimated leaf area index from the LiDAR metrics with linear regression with a standard error of 0.38. The results show that correlations between airborne laser metrics and different canopy field characteristics are very high if the field measurements are done with equivalent accuracy.     

A multisensor fusion approach to improve LAI time series

High-quality and gap-free satellite time series are required for reliable terrestrial monitoring. Moderate resolution sensors provide continuous observations at global scale for monitoring spatial and temporal variations of land surface characteristics. However, the full potential of remote sensing systems is often hampered by poor quality or missing data caused by clouds, aerosols, snow cover, algorithms and instrumentation problems. A multisensor fusion approach is here proposed to improve the spatio-temporal continuity, consistency and accuracy of current satellite products. It is based on the use of neural networks, gap filling and temporal smoothing techniques. It is applicable to any optical sensor and satellite product. In this study, the potential of this technique was demonstrated for leaf area index (LAI) product based on MODIS and VEGETATION reflectance data. The FUSION product showed an overall good agreement with the original MODIS LAI product but exhibited a reduction of 90% of the missing LAI values with an improved monitoring of vegetation dynamics, temporal smoothness, and better agreement with ground measurements.     

剪板机上刀架结构型式的优化设计

针对剪板机刀具间隙调整过程繁琐及上刀架结构存在的缺点,进行结构优化设计,简化刀具间隙调整方法,提高设备生产效率。     

基于Navier滑移的油膜缝隙微流动特性数值分析

针对液压系统中微米级油膜缝隙流动内的近壁面滑移微观尺度效应,采用计算流体力学(Computational fluid dynamics,CFD)方法分析壁面滑移作用对微米级油膜缝隙流动规律特性的影响。在对静压支承系统中封油边内油膜缝隙流动进行边界条件处理时,采取了壁面滑移速度与壁面滑移系数和当地局部速度梯度都成正比的Navier滑移模型边界条件。在数值模拟和理论基本吻合的基础上,进一步讨论分析壁面滑移系数对微米级油膜缝隙流动特性的影响,侧重分析考虑壁面表观粘度系数、温粘特性和非牛顿流体属性对微米级油膜缝隙流动特性分布和缝隙壁面滑移速度大小的影响。研究表明在微观尺度下具有界面滑移的油膜缝隙流动区别于无滑移的缝隙流动特性,壁面材料特性系数φ=0.01时,缝隙壁面的滑移速度越大,油膜缝隙流动分布均匀。其温粘特性将最大限度地影响壁面滑移速度大小和缝隙流动特性分布。     

活塞副泄漏的分析及实验研究

活塞副的泄漏对液压系统的工作性能和工作效率有很大影响;本文分析活塞副接触面的间隙、粗糙度、工作压力、运动速度、液体粘度等参数与泄漏的关系,采用有限元分析方法建立相应的数学模型,并通过试验得出了接触面磨损与泄漏的关系,提出了相对泄漏的评价准则。     

基于改进Otsu算法的游标卡尺缝隙检测

工业检测过程中,根据分辨率的高低,采集的图像分为加工纹理清晰和模糊两种情况。提出一种基于改进Otsu算法的游标卡尺卡爪缝隙检测方法,基于四叉树理论解决目标像素点较少时Otsu算法效果不好的问题。高分辨率图像下的游标卡尺表面纹理清晰,难以区分纹理特征和缝隙特征。为解决此问题,对采集的缝隙图像进行预处理,利用改进Otsu计算其阈值,进行边缘检测、缝隙特征提取和直线拟合,以完成对游标卡尺缝隙的自动检测和准确识别。建立一套实验装置,利用纹理清晰的缝隙图像验证所提缝隙检测方法的有效性。结果表明：该算法可以实现对缝隙边缘的精确自动提取和检测,同时单张图片的检测时间约为400 ms,满足工业实时检测的要求。     

光纤接头的菲涅尔反射损耗分析及其对传输特性的影响

本文对光纤接头的菲涅尔反应损耗进行了理论分析，并通过实验得出与理论基本一致的结论，最后讨论了光纤接头的菲涅尔反射对传输特性的影响。