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基于MATLAB的二孩政策下人口增长模型研究——以郑州市人口为例 被引量:1
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作者 田海丽 《河南教育学院学报(自然科学版)》 2017年第2期30-35,共6页
综合考虑影响二孩的各种因素,以郑州市历年人口数据为基础,给出二孩政策下人口增长模型函数——改进的Logistic模型,并采用MATLAB进行参数预测和函数建模;在建模过程中着重分析影响MATLAB建模性能优劣的两个关键因素:初值的设定和曲线... 综合考虑影响二孩的各种因素,以郑州市历年人口数据为基础,给出二孩政策下人口增长模型函数——改进的Logistic模型,并采用MATLAB进行参数预测和函数建模;在建模过程中着重分析影响MATLAB建模性能优劣的两个关键因素:初值的设定和曲线拟合的实现方式;用MATLAB仿真软件,尝试多种Logistic曲线拟合的方法,找出性能良好的Logistic函数实现方法,最终确定二孩政策下的郑州人口增长模型;对多种方法设置不同的初始值来检验拟合方法对初始值的宽容度,最终找出对初始值宽容度较高的两种MATLAB,实现Logistic曲线拟合的方法:nlinfit非线性拟合和lsqcurvefit最小二乘拟合. 展开更多
关键词 二孩人口增长模型 MATLAB Logic回归模型 初始值设置 曲线拟合方法
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基于免疫遗传算法的单神经元PID控制器设计
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作者 李晓龙 《软件导刊》 2008年第7期51-53,共3页
传统单神经元PID控制器中神经元比例系数及学习速率的初始值设置往往依靠经验,或先采用试凑法再根据曲线响应加以微调,针对这一缺点,提出了一种基于免疫遗传算法的单神经元PID控制器。将比例系数及学习速率作为待优化参数,通过参数寻优... 传统单神经元PID控制器中神经元比例系数及学习速率的初始值设置往往依靠经验,或先采用试凑法再根据曲线响应加以微调,针对这一缺点,提出了一种基于免疫遗传算法的单神经元PID控制器。将比例系数及学习速率作为待优化参数,通过参数寻优自行在搜索空间内获得全局最优点。仿真结果表明,新方法自适应能力更强、鲁棒性更好,不仅能够保证较好的控制效果,而且解决了传统方法初始值设置这一大难题。 展开更多
关键词 单神经元 免疫遗传算法 初始值设置 参数寻优
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Effects of Temperature, Salinity, Light Intensity, and pH on the Eicosapentaenoic Acid Production of Pinguiococcus pyrenoidosus 被引量:3
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作者 SANG Min WANG Ming +2 位作者 LIU Jianhui ZHANG Chengwu LI Aifen 《Journal of Ocean University of China》 SCIE CAS 2012年第2期181-186,共6页
The effects of temperature, light intensity, salinity, and initial pH on the growth and fatty acid composition of Pinguiococcus pyrenoidosus 2078 were studied for eicosapentaenoic acid (EPA) production potential. The ... The effects of temperature, light intensity, salinity, and initial pH on the growth and fatty acid composition of Pinguiococcus pyrenoidosus 2078 were studied for eicosapentaenoic acid (EPA) production potential. The fatty acid composition was assayed by gas chromatography-mass spectrometry, which indicated that the main fatty acids were C14:0, C16:0 and EPA. The highest EPA percentage 20.83% of total fatty acids was obtained at 20℃ with the temperature being set at 20, 24, and 28℃. Under different salinities and light intensities, the highest percentages of total polyunsaturated fatty acids (PUFAs) and EPA were 17.82% and 31.37% of total fatty acids, respectively, which were achieved at salinity 30 and 100μmol photon m-2s-1 illumination. The highest percentages of total PUFAs and EPA were 38.75% and 23.13% of total fatty acids, respectively, which were reached at an initial pH of 6 with the test range being from 5.0 to 9.0. 展开更多
关键词 Pinguiococcus pyrenoidosus TEMPERATURE light intensity SALINITY PH EPA fatty acids
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