Landslides are common natural hazards occurring in most parts of the world and have considerable adverse economic effects. Residual shear strength of clay is one of the most important factors in the determination of s...Landslides are common natural hazards occurring in most parts of the world and have considerable adverse economic effects. Residual shear strength of clay is one of the most important factors in the determination of stability of slopes or landslides. This effect is more pronounced in sensitive clays which show large changes in shear strength from peak to residual states. This study analyses the prediction of the residual strength of clay based on a new prediction model, functional networks（FN） using data available in the literature. The performance of FN was compared with support vector machine（SVM） and artificial neural network（ANN） based on statistical parameters like correlation coefficient（R）, Nash–Sutcliff coefficient of efficiency（E）, absolute average error（AAE）, maximum average error（MAE） and root mean square error（RMSE）. Based on R and E parameters, FN is found to be a better prediction tool than ANN for the given data. However, the R and E values for FN are less than SVM. A prediction equation is presented that can be used by practicing geotechnical engineers. A sensitivity analysis is carried out to ascertain the importance of various inputs in the prediction of the output.展开更多
恐惧情绪的研究对于动物情绪控制和发展有着重要意义。当前恐惧情绪对动物(尤其是鸟类)行为和脑活动的影响多偏重于行为学和生理学现象,缺乏涉及特定相关核团内神经电活动模式的动态分析研究。为了了解鸽子在恐惧情绪下的神经信号变化规...恐惧情绪的研究对于动物情绪控制和发展有着重要意义。当前恐惧情绪对动物(尤其是鸟类)行为和脑活动的影响多偏重于行为学和生理学现象,缺乏涉及特定相关核团内神经电活动模式的动态分析研究。为了了解鸽子在恐惧情绪下的神经信号变化规律,以鸽子为模式动物,以其脑室纤维膜周围灰质(stratum griseum periventriculare,SGP)核团为目标脑区,采用危险逐渐迫近的实验方法研究不同恐惧迫近距离下神经活动的变化模式,深入分析基于局部场电位(local field potential,LFP)信号的频域、时频能量和功能连接节律性差异。首先采集2只鸽子在静息状态和恐惧迫近实验的LFP信号,并提取Delta、Theta、Beta和Gamma这4个特征节律成分;然后采用自回归模型法计算了安静和恐惧两种状态在各节律下的功率谱密度占比差异;接着分析了恐惧状态下的时频能量随着迫近距离的变化的特异性变化;同时构建了基于相干性的脑功能网络,并对鸽子在安静和恐惧两种状态下的局部网络连接特性采用双因素方差分析方法进行了统计分析;最后对网络拓扑特征与迫近距离之间的关系进行了线性拟合分析。结果表明,鸽子恐惧迫近状态下Theta频段的功率谱占比和脑功能网络连接强度显著增加。随着迫近距离的缩短,Theta和Beta频段内的时频能量变化呈逐渐上升趋势,且局部网络连接强度与迫近距离之间呈现显著的负相关。说明Theta频段可能与恐惧情绪的表征有关,Theta和Beta频段的神经电信号特征差异能够表征恐惧迫近距离的变化。研究结果可以为进一步探索鸟类恐惧情绪的神经编码机制研究及其神经调控提供有价值的参考。展开更多
文摘Landslides are common natural hazards occurring in most parts of the world and have considerable adverse economic effects. Residual shear strength of clay is one of the most important factors in the determination of stability of slopes or landslides. This effect is more pronounced in sensitive clays which show large changes in shear strength from peak to residual states. This study analyses the prediction of the residual strength of clay based on a new prediction model, functional networks（FN） using data available in the literature. The performance of FN was compared with support vector machine（SVM） and artificial neural network（ANN） based on statistical parameters like correlation coefficient（R）, Nash–Sutcliff coefficient of efficiency（E）, absolute average error（AAE）, maximum average error（MAE） and root mean square error（RMSE）. Based on R and E parameters, FN is found to be a better prediction tool than ANN for the given data. However, the R and E values for FN are less than SVM. A prediction equation is presented that can be used by practicing geotechnical engineers. A sensitivity analysis is carried out to ascertain the importance of various inputs in the prediction of the output.
文摘恐惧情绪的研究对于动物情绪控制和发展有着重要意义。当前恐惧情绪对动物(尤其是鸟类)行为和脑活动的影响多偏重于行为学和生理学现象,缺乏涉及特定相关核团内神经电活动模式的动态分析研究。为了了解鸽子在恐惧情绪下的神经信号变化规律,以鸽子为模式动物,以其脑室纤维膜周围灰质(stratum griseum periventriculare,SGP)核团为目标脑区,采用危险逐渐迫近的实验方法研究不同恐惧迫近距离下神经活动的变化模式,深入分析基于局部场电位(local field potential,LFP)信号的频域、时频能量和功能连接节律性差异。首先采集2只鸽子在静息状态和恐惧迫近实验的LFP信号,并提取Delta、Theta、Beta和Gamma这4个特征节律成分;然后采用自回归模型法计算了安静和恐惧两种状态在各节律下的功率谱密度占比差异;接着分析了恐惧状态下的时频能量随着迫近距离的变化的特异性变化;同时构建了基于相干性的脑功能网络,并对鸽子在安静和恐惧两种状态下的局部网络连接特性采用双因素方差分析方法进行了统计分析;最后对网络拓扑特征与迫近距离之间的关系进行了线性拟合分析。结果表明,鸽子恐惧迫近状态下Theta频段的功率谱占比和脑功能网络连接强度显著增加。随着迫近距离的缩短,Theta和Beta频段内的时频能量变化呈逐渐上升趋势,且局部网络连接强度与迫近距离之间呈现显著的负相关。说明Theta频段可能与恐惧情绪的表征有关,Theta和Beta频段的神经电信号特征差异能够表征恐惧迫近距离的变化。研究结果可以为进一步探索鸟类恐惧情绪的神经编码机制研究及其神经调控提供有价值的参考。
