Diagnosis of a Moist Thermodynamic Advection Parameter in Heavy-Rainfall Events

A moist thermodynamic advection parameter,defined as an absolute value of the dot product of horizontal gradients of three-dimensional potential temperature advection and general potential temperature,is introduced to diagnose frontal heavy rainfall events in the north of China.It is shown that the parameter is closely related to observed 6-h accumulative surface rainfall and simulated cloud hydrometeors.Since the parameter is capable of describing the typical vertical structural characteristics of dynamic,thermodynamic and water vapor fields above a strong precipitation region near the front surface,it may serve as a physical tracker to detect precipitable weather systems near to a front.A tendency equation of the parameter was derived in Cartesian coordinates and calculated with the simulation output data of a heavy rainfall event.Results revealed that the advection of the parameter by the three-dimensional velocity vector,the covariance of potential temperature advection by local change of the velocity vector and general potential temperature,and the interaction between potential temperature advection and the source or sink of general potential temperature,accounted for local change in the parameter.This indicated that the parameter was determined by a combination of dynamic processes and cloud microphysical processes.     

Dieless drawing steel wires using a dielectric heating method and modeling the process dynamics

Modern industries require the production of multi-functional, inorganic, micron-sized metal wires. This study suggests a novel method that could potentially offer a highly efficient dieless drawing technology for manufacturing thin stainless steel fibers. The method is based on a hot-working principle, using microwaves as the heat source and SiC as the susceptor. Experimental trials with a laboratory rig showed that the new system worked effectively for drawing the stainless steel wires and should be able to realize the diameter attenuation with a diameter reduction of up to 21%. The theoretical model describing the deformation behavior of the stainless steel wires in the working zone along with the constitutive equation of Bingham model modified with a power law and Zener–Hollomon parameter turned out to match very good with the actual results of the experiment. The coefficient of variation of the drawn wire diameter increased, as the draw ratio increased, which could be attributed to the occurrence of the narrow necking zone.     

IMH4A2电梯专用变频器的技术特性

根据IMH4A2电梯专用变频器的技术特性 ,较详细地介绍了该种变频器的功能、控制信号、参数设置与监视、故障显示与处理及在使用中的注意事项。     

电力系统稳定性计算用励磁系统数学模型的完善

在已有电力系统稳定性计算用励磁系统数学模型(以下简称:励磁模型)的基础上,结合励磁系统的调研和参数测定工作,对励磁模型进行了4个方面的改进与完善;增加了并联PID控制;增加了PID控制的限幅环节;对原有晶闸管整流器模型进行了补充修订;对低励限制环节(UEL)的限制曲线设置进行了修改。     

异极性永磁偏置径向磁轴承的参数设计与实现

为了克服现有异极性永磁偏置径向磁轴承参数设计的不足,对一种异极性永磁偏置径向磁轴承进行了研究,分析其结构和工作原理。以其为对象提出了一种根据二维有限元仿真结果构建等效磁路,以满足承载力所需的偏置磁场与控制磁场的磁通量为基本目标;并以软磁材料不饱和为约束条件,结合等效磁路,推导出永磁材料和定转子结构的参数设计方法;设计了径向悬浮力400N的原理样机,进行了三维仿真分析和实验验证。结果表明:提出的参数设计方法合理,利用该方法设计的异极性永磁偏置径向磁轴承悬浮性能优良,为其他型永磁偏置磁轴承的研究奠定了基础。     

利用瞬态热栅法测定固体材料的热扩散率

实验采用两束脉冲激光干涉形成瞬态热栅的方法，测量了半导体、金属和合金等固体材料的热扩散率。将实验测定值、理论预计值及公认值进行了比较，并对比较的结果进行了分析讨论，说明瞬态热栅法是定征固体热学性质及结构的灵敏且有效的方法。此外，在实验过程中还检测到固体材料表面附近空气中存在的界面波。     

一种半集总微波带通滤波器的设计

本文设计了一种适用于阵列天线的带通滤波器,主要用于抑制杂波干扰。该滤波器以传统椭圆函数滤波器设计理论为基础,并对输入输出端口进行高低通包络匹配,从而解决了椭圆函数滤波器带外抑制平缓的问题 。为了满足滤波器设计指标的要求,电路采用半集总参数思路实现。文中给出了该滤波器的设计过程及实际测量结果。实测结果和仿真结果相符合,满足技术指标要求。     

摄像机标定中的角点提取方法及改进

简述了摄像机标定的原理,分别采用Harris角点提取法和改进的Harris角点提取法提取角点的两组图像坐标,采用Tsai标定法标定,并使用标定结果重构世界坐标,比较了两者的误差．     

相控阵雷达资源受限时搜索参数调整策略

相控阵雷达最主要的工作方式为搜索和跟踪,针对跟踪任务抢占雷达总资源导致搜索性能下降的问题,文中在搜索空域需要适时进行调整的条件下,考虑到扫描过程中产生的波束展宽效应,提出了以空域覆盖系数为优化函数的资源受限时的搜索性能优化模型,给出了波束宽度调整(ABW)、观测空域调整(AOA)和波束宽度和观测空域联合调整(ABWAOA)三种策略,通过仿真比较了三种参数调整策略的搜索性能,结果表明ABWAOA策略的调度性能最优。     

基于红外成像的小型化稳定平台参数辨识

针对红外成像的小型化稳定平台参数辨识的问题,对系统中非线性因素进行尽可能抑制,并在高速环境下对系统进行辨识.在辨识过程中,利用伪随机信号(Pseudo random binary signal,PRBS)作为调制的输入电压信号对系统激励,相应的系统输出响应为速度信号,并应用增广最小二乘方法辨识线性离散模型参数,最后通过参数化和非参数化两种方式,对辨识模型的精确度进行了验证.结果表明:辨识得到的用来衡量实际系统输出随输入变化的传函关系的参数模型,能够反映真实系统的动态特性,满足辨识精度要求.