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脉冲密度调节谐振逆变器的功率控制技术
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作者 朱辉 黄潇潇 +2 位作者 彭咏龙 李亚斌 王海滨 《通信电源技术》 2012年第4期16-19,共4页
脉冲密度调节谐振逆变器主要优点在于调节负载功率的同时能够保证逆变器开关器件始终工作在零电压和零电流开关状态,整个运行过程都具有较高的负载功率因数和较低的谐波畸变率。然而,脉冲密度调节谐振逆变器的输出功率响应往往是离散和... 脉冲密度调节谐振逆变器主要优点在于调节负载功率的同时能够保证逆变器开关器件始终工作在零电压和零电流开关状态,整个运行过程都具有较高的负载功率因数和较低的谐波畸变率。然而,脉冲密度调节谐振逆变器的输出功率响应往往是离散和非线性的,这就要求找出一种控制策略能够实现可靠地负载功率调节。文中针对脉冲密度调节谐振逆变器提出了一种基于CycloneⅡ可编程门阵列的预期算法和滞环比较的实现方案。仿真实验结果表明这种控制方法能够在较大的范围内实现精确的功率调节。 展开更多
关键词 脉冲密度调节 预期算法 滞环比较 逻辑控制器
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A new support vector machine optimized by improved particle swarm optimization and its application 被引量:3
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作者 李翔 杨尚东 乞建勋 《Journal of Central South University of Technology》 EI 2006年第5期568-572,共5页
A new support vector machine (SVM) optimized by an improved particle swarm optimization (PSO) combined with simulated annealing algorithm (SA) was proposed. By incorporating with the simulated annealing method, ... A new support vector machine (SVM) optimized by an improved particle swarm optimization (PSO) combined with simulated annealing algorithm (SA) was proposed. By incorporating with the simulated annealing method, the global searching capacity of the particle swarm optimization(SAPSO) was enchanced, and the searching capacity of the particle swarm optimization was studied. Then, the improyed particle swarm optimization algorithm was used to optimize the parameters of SVM (c,σ and ε). Based on the operational data provided by a regional power grid in north China, the method was used in the actual short term load forecasting. The results show that compared to the PSO-SVM and the traditional SVM, the average time of the proposed method in the experimental process reduces by 11.6 s and 31.1 s, and the precision of the proposed method increases by 1.24% and 3.18%, respectively. So, the improved method is better than the PSO-SVM and the traditional SVM. 展开更多
关键词 support vector machine particle swarm optimization algorithm short-term load forecasting simulated annealing
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Short-term forecasting optimization algorithms for wind speed along Qinghai-Tibet railway based on different intelligent modeling theories 被引量:8
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作者 刘辉 田红旗 李燕飞 《Journal of Central South University》 SCIE EI CAS 2009年第4期690-696,共7页
To protect trains against strong cross-wind along Qinghai-Tibet railway, a strong wind speed monitoring and warning system was developed. And to obtain high-precision wind speed short-term forecasting values for the s... To protect trains against strong cross-wind along Qinghai-Tibet railway, a strong wind speed monitoring and warning system was developed. And to obtain high-precision wind speed short-term forecasting values for the system to make more accurate scheduling decision, two optimization algorithms were proposed. Using them to make calculative examples for actual wind speed time series from the 18th meteorological station, the results show that: the optimization algorithm based on wavelet analysis method and improved time series analysis method can attain high-precision multi-step forecasting values, the mean relative errors of one-step, three-step, five-step and ten-step forecasting are only 0.30%, 0.75%, 1.15% and 1.65%, respectively. The optimization algorithm based on wavelet analysis method and Kalman time series analysis method can obtain high-precision one-step forecasting values, the mean relative error of one-step forecasting is reduced by 61.67% to 0.115%. The two optimization algorithms both maintain the modeling simple character, and can attain prediction explicit equations after modeling calculation. 展开更多
关键词 train safety wind speed forecasting wavelet analysis time series analysis Kalman filter optimization algorithm
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微观计量分析中缺失数据的极大似然估计 被引量:6
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作者 孙凤 《数量经济技术经济研究》 CSSCI 北大核心 2005年第11期51-56,共6页
微观计量经济分析中常常遇到缺失数据,传统的处理方法是删除所要分析变量中的缺失数据,或用变量的均值替代缺失数据,这种方法经常造成样本有偏。极大似然估计方法可以有效地处理和估计缺失数据。本文首先介绍缺失数据的极大似然估计方法... 微观计量经济分析中常常遇到缺失数据,传统的处理方法是删除所要分析变量中的缺失数据,或用变量的均值替代缺失数据,这种方法经常造成样本有偏。极大似然估计方法可以有效地处理和估计缺失数据。本文首先介绍缺失数据的极大似然估计方法,然后对一实际调查数据中的缺失数据进行极大似然估计,并与传统处理方法的估计结果进行比较和评价。 展开更多
关键词 极大似然估计 预期-最大算法 缺失数据
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