负角保护针在降低220 kV线路雷电绕击方面的应用

针对地处山坡或山顶的输电线路经常出现雷电绕击导线引起线路跳闸的现象,以“闪击距离”的概念为理论基础,在220 kV线路杆塔上采取装设负角保护针的措施,有效地防止了输电线路遭受雷电绕击,大大地降低了线路跳闸率,提高了输电线路安全运行水平。     

基于夫琅禾费衍射的激光束散角外场检测

基于圆孔衍射原理,通过对菲涅耳衍射和夫琅禾费衍射特性的对比分析,综合圆孔夫琅禾费衍射光强艾里斑分布特征,提出了一种基于夫琅禾费衍射的激光束散角检测方法,通过布设激光靶对激光远场光斑进行采集、分析、处理,得到激光器关键性能参数束散角的实测值。测量结果表明:采用该方法可获得较高的检测精度,并对影响测量精度的因素进行了分析,该方法可为激光器束散角外场检测提供科学指导。     

轮式牵引车传动系扭转自激振动的分析

将牵引车的传动系简化为一个2自由度的扭转振动系统,并以二阶微分方程描述.通过构造内外境界线,基于环域定理证明在满足两个代数不等式的条件下该微分方程必有极限环,从而给出系统产生扭转自激振动的条件.数值计算表明,自激振动的振幅与初始滑转率相关.最后,提出通过增加传动系扭转阻尼来防止在任何初始滑转率下发生剧烈的扭转自激振动的措施.     

硅片处理预对准系统的研究

介绍了所研制的12 in硅片预对准系统．首先,根据硅片预对准系统的任务和流程设计了系统的结构．其次,设计了预对准检测算法,采用最小二乘圆法对硅片圆心进行定位;提出了检测硅片缺口的边缘变化率法和计算缺口基准点的曲线拟合法．对预对准系统进行了误差分析．最后,采用光学式预对准方法,对12 in硅片进行了预对准实验研究．实验结果表明硅片缺口的重复定位精度小于48 μm,预对准时间为23 s,满足设计要求．     

新型大相对孔径Schwarzschild光谱成像系统设计

为满足高分辨率大相对孔径宽波段高光谱成像仪的要求,克服Offner光谱成像系统中凸面光栅加工的困难和改进型Czerny-Turner光谱成像系统相对孔径小的缺点,提出一种新型的基于平面光栅的大相对孔径Schwarzschild光谱成像系统,根据反射球面罗兰圆理论分析了该系统的像散校正方法,利用Matlab软件编制了初始结构快速计算程序。作为实例,设计了一个相对孔径为1/2.5,工作波段为400~1000nm的Schwarzschild光谱成像系统。首先利用自己编制的Matlab程序计算初始结构参数,再利用Zemax-EE光学设计软件对该光谱成像系统进行光线追迹和优化设计,并对设计结果进行分析。结果表明,在整个工作波段内,点列图弥散斑的尺寸小于13μm,实现了大相对孔径宽波段像差的同时校正,在宽波段内获得了良好的成像质量,满足设计指标要求,也证明了这种新型Schwarzschild光谱成像系统是可行的,其在航空和航天高光谱遥感领域具有广阔的应用前景。     

分离燃尽风水平摆角对1000 MW八角切圆锅炉燃烧特性影响的数值研究

以某1000 MW八角双切圆锅炉为研究对象,采用数值模拟方法分析了分离燃尽风(SOFA)水平摆角对炉膛出口烟气温度、速度以及炉内主要燃烧产物分布的影响.结果 表明:将SOFA水平摆角正向增大5°时可同时降低CO与NOx排放量;正向增大SOFA水平摆角,即SOFA正旋切圆直径增大,炉膛出口两侧逐渐出现双峰型高温烟气区,烟...     

消费空间生产视角下杭州市美丽乡村发展特征——以下满觉陇、龙井、龙坞为例

在新型城镇化背景下,传统乡村的更新升级日益与大都市消费空间扩张、农业现代化紧密联系在一起。以杭州为例,其外围乡村地域已经形成动力机制各异的不同消费空间圈层模式,研究选取3个典型美丽乡村为案例分析对象,构建美丽指数对其现状特征进行评价,并探索各自不同的动力机制。结论是,3个乡村均具有生产与消费兼具的地域空间特征,在人居环境、社会文化、产业经济方面具有一定的差异性,这是由于受不同的动力主体推动所致,由此也形成了都市化背景下乡村空间的圈层模式。     

Packing equal circles into a circle with circular prohibited areas

The paper considers the problem of packing a maximal number of identical circles of a given radius into a multiconnected domain. The domain is a circle with prohibited areas to be finite unions of circles of given radii. We construct a mathematical model of the problem and investigate its characteristics. The starting points are constructed in a random way or on the ground of the hexagonal lattice. To find the local maxima, a modification of the Zoutendijk method of feasible directions and a strategy of active inequalities are applied. We compare our results with the benchmark instances of packing circles into circular and annular containers. A number of numerical examples are given.     

Hand gesture recognition using valley circle feature and Hu’s moments technique for robot movement control

Hand gesture recognition is a simpler and more natural way of human computer interaction. The goal of this paper is to detect the continuous gestures and use them to convey information for the robot movement control. So the hand gesture recognition requires fast and extremely robust. In this paper, three strategies were used to realize the hand gesture recognition: (1) the valley circle (VC) was created for the first stage of 6 fingertip numbers classification; (2) the hybrid feature vector of Hu’s moments, convexity and compactness (HCC) were constructed for the second stage of gesture recognition of the remainder unknown gesture classes; (3) a new template matching recognition (NTMR) algorithm was proposed to realize 10 gesture classes recognition. To test the hand gesture recognition method, the robot movement control system was built. It is experimental proved that the NTMR algorithm is effective and corrective for the hand gesture recognition. It increased the recognition accuracy by 4% and decreased the recognition duration by 112 ms compared with Hu’s moment method. It had good performances of the real-time hand gesture acquisition and information conveyance, and it had the invariant properties when the gesture was rotated and shifted and scaled.     

水泵转子径向圆跳动检测数据修正

针对应用千分表和电涡流传感器进行水泵转子径向圆跳动检测时,检测结果出现正弦变化规律的现象,分析了安装偏心误差对检测结果的影响原理,建立了相应的数学模型.运用最小二乘拟合法计算出变化曲线的幅值及初相位,从而消除偏心误差实现误差分离.结果表明,当将所提方法应用在水泵转子径向圆跳动检测的工程实践中时,可以有效消除安装偏心引起的误差,从而提高检测精确度.拟合平方和误差约为0. 000 9,所提方法可以广泛应用于轴类工件的检测实践.