可变速风力发电系统综述

介绍风力发电的发展状况,分析了风力发电的技术动态,说明可变速发电方式和风车大型化的优点。详述同步发电机配备大功率变频装置和双重励磁绕线式转子异步发电机配备电力变换装置的两种方式。今后风力发电将始终围绕着降低成本、提高系统稳定性和可靠性这几个要点,得到广泛应用,成为对国民经济有着举足轻重影响的产业。     

Triangle-based key management scheme for wireless sensor networks

For security services in wireless sensor networks, key management is a fundamental building block. In this article, we propose a triangle-based key predistribution approach and show that it can improve the effectiveness of key management in wireless sensor networks. This is achieved by using the bivariate polynomial in a triangle deployment system based on deployment information about expected locations of the sensor nodes. The analysis indicates that this scheme can achieve higher probability of both direct key establishment and indirect key establishment. On the other hand, the security analysis shows that its security against node capture would increase with a decrease of the sensor node deployment density and size of the deployment model and an increase of the polynomial degree.     

基于ControlLogix PLC的水利工程自动化系统

简要介绍了水利工程信息自动化系统原理与结构.研讨罗克韦尔ControlLogix系列PLC的功能特性及其在水利工程信息自动化系统中的应用。     

高性能InGaAs/AlAs共振隧穿二极管的研制与器件模拟分析

在半绝缘的InP衬底上采用分子束外延的方法生长制备了不同势垒厚度的RTD材料样品,室温下测量的最高峰-谷电流比为18.39.通过模拟得到RTD直流特性与势垒厚度、势阱材料及厚度、隔离层厚度以及掺杂浓度间的关系,对结果进行了分析与讨论.     

气藏采收率影响因素研究与启示——以靖边气田A井区为例

以鄂尔多斯盆地靖边气田A井区为例,采用单因素相关分析和数值模拟方法,对比研究了井网控制程度、储层物性及地层废弃压力对气藏采收率影响及其主次关系。结果表明,井网控制程度是影响采收率的首要因素,井网控制程度每增加10%,采收率提高8.5%;渗透率是影响采收率的重要因素,渗透率每增加10%,采收率平均增加6%;废弃压力对采收率亦有较大影响,废弃压力每降低10%,采收率可提高1.6%。三者对采收率影响综合排序为：井网控制程度>储层物性>废弃压力。分析认为,渗透率是储层固有属性,很难从根本改变;而废弃压力受井口外输压力和增压开采成本制约,降低幅度有限。因此,优化井网及增加井网控制程度是提高气藏采收率的有效途径。研究成果具有实践意义,可为改进气田开发方式和提高气藏采收率提供参考。     

最小化拖期任务数并行机调度问题的一种基于知识的遗传算法

本文研究了最小化拖期任务数并行调度问题,提出了一种基于知识的遗传算法,并在问题的描述、遗传算法编码、初始种群的产生办法、交叉方法、变异方法等方面作了研究,不同规模问题的数值计算结果表明了本文提出的基于知识的遗传算法优于目前为止最好的启发式算法和普通的遗传算法,并且能适应于较大规模的并行机调度问题。     

Self‐Healing,Flexible, and Tailorable Triboelectric Nanogenerators for Self‐Powered Sensors based on Thermal Effect of Infrared Radiation

Self‐healing triboelectric nanogenerators (TENGs) with flexibility, robustness, and conformability are highly desirable for promising flexible and wearable devices, which can serve as a durable, stable, and renewable power supply, as well as a self‐powered sensor. Herein, an entirely self‐healing, flexible, and tailorable TENG is designed as a wearable sensor to monitor human motion, with infrared radiation from skin to promote self‐healing after being broken based on thermal effect of infrared radiation. Human skin is a natural infrared radiation emitter, providing favorable conditions for the device to function efficiently. The reversible imine bonds and quadruple hydrogen bonding (UPy) moieties are introduced into polymer networks to construct self‐healable electrification layer. UPy‐functionalized multiwalled carbon nanotubes are further incorporated into healable polymer to obtain conductive nanocomposite. Driven by the dynamic bonds, the designed and synthesized materials show excellent intrinsic self‐healing and shape‐tailorable features. Moreover, there is a robust interface bonding in the TENG devices due to the similar healable networks between electrification layer and electrode. The output electric performances of the self‐healable TENG devices can almost restore their original state when the damage of the devices occurs. This work presents a novel strategy for flexible devices, contributing to future sustainable energy and wearable electronics.     

基于等离子体镜的太赫兹单脉冲选择方法

研究了一种用于中国工程物理研究院太赫兹自由电子激光装置(CTFEL)输出的太赫兹的单脉冲选择方法,以满足一些对太赫兹脉冲的时间分辨率和峰值强度提出较高要求同时要保证较低平均功率的实验的需要。利用自诱导等离子体开关技术,太赫兹能够被短脉冲激光打靶产生的等离子体镜反射,从而使等离子体镜可以作为门控开关,选出单个太赫兹微脉冲。通过理论分析计算出等离子体临界密度和激光功率密度阈值,采用辐射流体模拟软件对激光打靶过程进行数值模拟。模拟结果表明,激光激发出的等离子体密度远大于临界密度。由此证明了实验的可行性,进而给出实验所需装置的参数指标以及实验光路设计。     

激光深熔焊等离子体电信号振荡特征与焊缝熔深的特征关系

针对激光深熔焊接过程的监控问题,基于小孔内部压力平衡条件分析了小孔振荡和小孔深度的关系。在此基础上基于小孔行为与等离子体行为的耦合性,以及等离子体振荡特征与等离子体电信号波动特征的一致性,利用短时自相关分析方法分析了A304不锈钢和Q235碳钢在激光深熔焊接过程中等离子体电信号振荡周期与焊缝熔深之间的关系。结果表明,等离子体电信号振荡周期随焊缝熔深的增加而增大,并且不同焊接材料的等离子体电信号振荡周期与焊缝熔深之间的关系不同。最后,在可变热输入连续焊接验证实验中,在焊接过程稳定的条件下,等离子体电信号的短时自相关分析结果与焊缝熔深之间有比较好的对应关系,与所分析的小孔振荡特征方程具有一致性。     

一种新的含噪混沌信号降噪算法

该文针对低信噪比、非高斯加性噪声和混沌动力学系统参数未知的含噪混沌信号降噪问题,提出了一种基于粒子滤波(Particle Filtering, PF)的降噪新算法。该算法将混沌信号和动力学系统中的未知参数作为一个多维状态矢量,利用PF方法递推计算多维状态矢量的联合后验概率分布,进而实现了对混沌信号的最优估计。对于混沌信号轨道分离过快所导致的退化问题,提出了有效的解决方法,并利用核平滑和自回归(Auto-Regression, AR)模型建模的方法分别实现了非时变以及时变参数的递推估计。仿真实验的结果表明,与现有的降噪方法相比,该文提出的新算法能够更加有效地抑制含噪混沌信号中的加性噪声。