老旧机动车淘汰更新及补贴政策的成本有效性分析——以北京市为例

以氮氧化物和PM_2.5削减量为减排效果评估指标, 以车辆残值成本、政策执行成本、燃油成本节约为社会成本指标, 借助单位减排产生的社会成本(社会成本/减排量比值), 对北京市2011年6月至2020年12月老旧机动车淘汰更新及补贴政策的实施效果进行成本有效性分析。结果表明, 研究覆盖期内, 该政策的成本有效性并非单调递减, 而是呈现阶段性和结构性特点: 在重点淘汰柴油货车时期, 政策成本有效性最佳, 在重点淘汰国III汽油车时期, 成本有效性较差, 两者氮氧化物及PM_2.5单位污染物减排成本分别相差14倍和34倍; 随着车型拓展到更高排放标准, 淘汰小型客车的成本有效性呈下降趋势, 国III和国IV排放标准的小型客车减排潜力已较为有限, 且成本有效性远低于政策早期; 淘汰重型货车的成本有效性较高, 且在部分时期存在社会成本的节约。建议后续相关政策的制定应基于成本有效性, 审慎地将排放标准更高的小型客车纳入该政策管制范围, 应更关注重型柴油货车加速淘汰的政策设计优化。     

An Improved Composite Multiscale Fuzzy Entropy for Feature Extraction of MI-EEG

Motor Imagery Electroencephalography (MI-EEG) has shown good prospects in neurorehabilitation, and the entropy-based nonlinear dynamic methods have been successfully applied to feature extraction of MI-EEG. Especially based on Multiscale Fuzzy Entropy (MFE), the fuzzy entropies of the τ coarse-grained sequences in τ scale are calculated and averaged to develop the Composite MFE (CMFE) with more feature information. However, the coarse-grained process fails to match the nonstationary characteristic of MI-EEG by a mean filtering algorithm. In this paper, CMFE is improved by assigning the different weight factors to the different sample points in the coarse-grained process, i.e., using the weighted mean filters instead of the original mean filters, which is conductive to signal filtering and feature extraction, and the resulting personalized Weighted CMFE (WCMFE) is more suitable to represent the nonstationary MI-EEG for different subjects. All the WCMFEs of multi-channel MI-EEG are fused in serial to construct the feature vector, which is evaluated by a back-propagation neural network. Based on a public dataset, extensive experiments are conducted, yielding a relatively higher classification accuracy by WCMFE, and the statistical significance is examined by two-sample t-test. The results suggest that WCMFE is superior to the other entropy-based and traditional feature extraction methods.     

基于MATLAB的异步电动机线性化控制系统的仿真

从异步电动机在同步旋转坐标系下的状态方程出发，在一定的条件下，对其系数矩阵简化．推出异步电动机的线性化控制模型．并基于该模型得出异步电动机的线性化控制系统．以给定电机为例，对该模型的有效性、响应用MATLAB进行仿真分析．验证的结果说明上述模型具有实用价值．     

0.8W/80K直线驱动斯特林制冷机的研制

介绍了一种 0 .8W/ 80 K分置式斯特林制冷机。该制冷机采用当前国外先进的直线电机驱动 ,双活塞对称布置结构。该制冷机已通过军品所要求的环境试验 ,输入功率小于 4 0 W(DC)情况下 ,其 +6 0℃高温环境下制冷量≥ 0 .5 W/ 80 K ,带载 0 .5 W工况下 MTTF已突破 2 0 0 0小时。文中主要论述了其工作原理、结构特点、试验情况。     

基于PC的电机云母槽自动下刻机测控系统的设计

采用工业用计算机实现自动下刻电机云母槽测控系统的设计方法.在加工工艺允许的情况下,系统采用接触式的检测方法能降低成本,提高可靠性,并提高其自动化的水平.在软件设计上,系统由找槽控制算法和下刻深度算法双闭环控制组成,槽控制算法与下刻深度算法之间相互切换直到加工完电机的所有槽.     

Rotation of a Fine Particle with Circularly Polarized Anti-Parallel Collinear Laser Beams

We have succeeded in the operation of rotating a fine particle which was held without mechanical contact by circularly polarized laser beams with opposite propagation directions. A polystyrene latex particle 11.9 μm in diameter deformed in a disk-like shape was dispersed in water, and was trapped using the anti-parallel collinear laser beams which were set up so that they had the circular polarization rotating in the same direction. It was observed that the trapped particle rotated in the same direction as the rotation of the circular polarization of light. Inversion of the rotational direction of the circular polarization of light reversed the direction of the rotation of the particle. Although the rotational speed of a particle varied significantly from particle to particle, it was found to be proportional to the laser beam intensity. A typical value for the rotational speed per beam intensity was 2.1 Hz/W.     

300 km·h-1电动车组制动参数研究

在我国研制的先锋号电动车组制动系统的基础上 ,借鉴国外高速列车的经验 ,对自行研制 30 0km·h-1高速动车组制动系统的重要参数进行了研究 ,并提出了可供运用的设计值 .通过对先锋号动车组和 30 0km·h-1高速动车组制动参数的比较分析 ,指出先锋号制动系统的模式比较适合于 30 0km·h-1动车组 .     

离心式风机导流器调节的经济性分析

全面分析和比较了G4－73型离心风机在较大负荷变化范围内分别采用轴向导流器调节和轴向导流器加双速电动机调节的运行经济性，对各种风机的节能具有重要的指导意义。     

感应加热钢包炉电磁与结构优化

感应加热钢包炉是国外新发展的一种二次精炼及加热设备，具有高效、低能耗、无污染的特点，本文在感应加热钢包炉电磁与结构分析工作的基础上，用电磁场数值模拟方法对感应加热钢包炉的电磁设计和包壳结构进行优化。     

光束偏转法自动测试激光等离子体冲击波系统的研制

根据光束偏转原理，研制了激光等离子体冲击波自动测试系统的硬件和软件。该系统使用计算机与可编程序控制器作为上下位机，采取上下位机通讯的方式控制步进电机及二维移动架的移动，以改变探测光的相对位置，并利用单模光纤和光电倍增管将探测到的光偏转信号传入数字示波器进行存储，最后计算机将示波器中采集到的光偏转信号进行分析处理。使用该系统对激光等离子冲击波的衰减过程进行了实际测试，得到了较为理想的实验结果。