分析我国常见呼吸道传染病疫情发病的波动规律,揭示季节特征、长期趋势特征和循环周期特征,为制定防控策略提供科学依据。基于Census X-13季节调整法分析呼吸道传染病的季节特征与波动规律,使用HP(Hodrick-Prescott)滤波法剖析呼吸道传...分析我国常见呼吸道传染病疫情发病的波动规律,揭示季节特征、长期趋势特征和循环周期特征,为制定防控策略提供科学依据。基于Census X-13季节调整法分析呼吸道传染病的季节特征与波动规律,使用HP(Hodrick-Prescott)滤波法剖析呼吸道传染病的长期趋势和循环周期,同时构建整合移动平均自回归模型(autoregressive integrated moving average model,ARIMA)乘积季节模型预测呼吸道传染病的发病趋势。结果显示,我国常见呼吸道传染病具有季节性变动特征,季节因素的贡献率为35.40%,当年的12月至次年的1、4、5月为波动最高峰,当年的10月和2月为波动最低谷。呼吸道传染病的循环波动大致将整体分为3个完整的周期,循环周期变长,波峰上升。根据贝叶斯信息准则(Bayesian Information Criterion,BIC)最小和平稳R^(2)最大准则确定最佳模型为ARIMA(1,0,2)(1,0,0)_(12),拟合的预测值与实际发病值基本一致。根据呼吸道传染病的季节特征与循环周期特征,构建ARIMA乘积季节模型,为制定呼吸道传染病的预防控制措施和优化卫生资源配置提供科学依据。展开更多
The hydrogen absorption of the LaFe（10.9）-Co（0.8）Si（1.3） compound under constant 1.01 × 10-5 Pa H2 gas in a flow hydrogen atmosphere was studied. The effects of hydrogen absorption on structure, Curie tempe...The hydrogen absorption of the LaFe（10.9）-Co（0.8）Si（1.3） compound under constant 1.01 × 10-5 Pa H2 gas in a flow hydrogen atmosphere was studied. The effects of hydrogen absorption on structure, Curie temperature, phase transition and magnetic property were investigated by X-ray diffraction（XRD）, differential scanning calorimeter（DSC） and superconducting quantum interference device,respectively. The hydrides of LaFe（10.9）Co（0.8）Si（1.3） crystallize into NaZn（13）-type structural phase after hydrogen absorption at temperature from 548 to 623 K. Lower hydrogen absorption temperature is of no advantage for pure 1：13 phase formation in a flow H2 atmosphere. The Curie temperature（TC） of LaFe（10.9）Co（0.8）Si（1.3） compound increases by70 K or more after hydrogen absorption. For LaFe（10.9）-Co（0.8）Si（1.3）H（1.8） compound, the maximum magnetic entropy change and the relative cooling power under a magnetic field change of 0-2 T are 6.1 J·kg^-1·K^-1 and 170 J·kg^-1,respectively. Large refrigerant capacity, low hysteresis loss and wide temperature span of magnetic entropy change peak make it a competitive practical candidate for magnetic refrigerant.展开更多
文摘分析我国常见呼吸道传染病疫情发病的波动规律,揭示季节特征、长期趋势特征和循环周期特征,为制定防控策略提供科学依据。基于Census X-13季节调整法分析呼吸道传染病的季节特征与波动规律,使用HP(Hodrick-Prescott)滤波法剖析呼吸道传染病的长期趋势和循环周期,同时构建整合移动平均自回归模型(autoregressive integrated moving average model,ARIMA)乘积季节模型预测呼吸道传染病的发病趋势。结果显示,我国常见呼吸道传染病具有季节性变动特征,季节因素的贡献率为35.40%,当年的12月至次年的1、4、5月为波动最高峰,当年的10月和2月为波动最低谷。呼吸道传染病的循环波动大致将整体分为3个完整的周期,循环周期变长,波峰上升。根据贝叶斯信息准则(Bayesian Information Criterion,BIC)最小和平稳R^(2)最大准则确定最佳模型为ARIMA(1,0,2)(1,0,0)_(12),拟合的预测值与实际发病值基本一致。根据呼吸道传染病的季节特征与循环周期特征,构建ARIMA乘积季节模型,为制定呼吸道传染病的预防控制措施和优化卫生资源配置提供科学依据。
基金financially supported by the Tianjin Research Program of Application Foundation and Advanced Technology (No.14JCQNJC04000)the National Key Research and Development Program of China (No.2017YFB0702700)the Hebei Provincial Education Department Project (No.ZD2017066)
文摘The hydrogen absorption of the LaFe（10.9）-Co（0.8）Si（1.3） compound under constant 1.01 × 10-5 Pa H2 gas in a flow hydrogen atmosphere was studied. The effects of hydrogen absorption on structure, Curie temperature, phase transition and magnetic property were investigated by X-ray diffraction（XRD）, differential scanning calorimeter（DSC） and superconducting quantum interference device,respectively. The hydrides of LaFe（10.9）Co（0.8）Si（1.3） crystallize into NaZn（13）-type structural phase after hydrogen absorption at temperature from 548 to 623 K. Lower hydrogen absorption temperature is of no advantage for pure 1：13 phase formation in a flow H2 atmosphere. The Curie temperature（TC） of LaFe（10.9）Co（0.8）Si（1.3） compound increases by70 K or more after hydrogen absorption. For LaFe（10.9）-Co（0.8）Si（1.3）H（1.8） compound, the maximum magnetic entropy change and the relative cooling power under a magnetic field change of 0-2 T are 6.1 J·kg^-1·K^-1 and 170 J·kg^-1,respectively. Large refrigerant capacity, low hysteresis loss and wide temperature span of magnetic entropy change peak make it a competitive practical candidate for magnetic refrigerant.
