Rock bursts represent a formidable challenge in underground engineering,posing substantial risks to both infrastructure and human safety.These sudden and violent failures of rock masses are characterized by the rapid ...Rock bursts represent a formidable challenge in underground engineering,posing substantial risks to both infrastructure and human safety.These sudden and violent failures of rock masses are characterized by the rapid release of accumulated stress within the rock,leading to severe seismic events and structural damage.Therefore,the development of reliable prediction models for rock bursts is paramount to mitigating these hazards.This study aims to propose a tree-based model—a Light Gradient Boosting Machine(LightGBM)—to predict the intensity of rock bursts in underground engineering.322 actual rock burst cases are collected to constitute an exhaustive rock burst dataset,which serves to train the LightGBMmodel.Two population-basedmetaheuristic algorithms are used to optimize the hyperparameters of the LightGBM model.Finally,the sensitivity analysis is used to identify the predominant factors that may incur the occurrence of rock bursts.The results show that the population-based metaheuristic algorithms have a good ability to search out the optimal hyperparameters of the LightGBM model.The developed LightGBM model yields promising performance in predicting the intensity of rock bursts,with which accuracy on training and testing sets are 0.972 and 0.944,respectively.The sensitivity analysis discloses that the risk of occurring rock burst is significantly sensitive to three factors:uniaxial compressive strength(σc),stress concentration factor(SCF),and elastic strain energy index(Wet).Moreover,this study clarifies the particular impact of these three factors on the intensity of rock bursts through the partial dependence plot.展开更多
针对储能电池组在电网典型储能工况下荷电状态(state of charge,SOC)估算精度较低的问题,提出一种基于核主成分分析(kernel principal component analysis,KPCA)-鹈鹕优化(pelican optimization algorithm,POA)-双向门控循环单元(bidire...针对储能电池组在电网典型储能工况下荷电状态(state of charge,SOC)估算精度较低的问题,提出一种基于核主成分分析(kernel principal component analysis,KPCA)-鹈鹕优化(pelican optimization algorithm,POA)-双向门控循环单元(bidirectional gated recurrent unit,Bi GRU)的SOC估计模型。通过设计调峰/调频工况下电池组充放电实验,从数据中提取表征SOC变化的融合特征作为模型输入;分别构建不同工况下Bi GRU网络,并利用POA对其超参数进行优化,提高模型性能;进一步在混合工况下验证模型的有效性。结果表明,所建模型有着更好的SOC估计效果和更强的鲁棒性,能够提高复杂储能工况下储能电池组SOC估计精度。展开更多
Literature on spot-billed pelican has not been reviewed lately which could provide a critique of the emerging data. We have now chosen it as a key species through which we suggest a conservation action plan which will...Literature on spot-billed pelican has not been reviewed lately which could provide a critique of the emerging data. We have now chosen it as a key species through which we suggest a conservation action plan which will benefit several waterbird species. The information provided here is scholastic in nature and is meant to focus on aspects that require attention and help plan future work for applied conservation. All known information on this species is brought together in this review which will also provide an update of its biology. Notes on the breeding biology of the species first published in the Journal of the Bombay Natural History Society. So far, 380 works have appeared on the species; of these, 36 contain material reported in earlier works or appeared as papers subsequently. Most appeared as articles in journals, both national and regional, a few international journals, newsletters/bulletins （48.2%）, 4 dissertations, 76 reports and 6 popular science articles in magazines. This review on the species will provide an insight into different factors that can be weighed and combined while making a decision in investing resources in species conservation, i.e. importance of the species, level of threat and the time frame over which results are to be achieved.展开更多
《新塘鹅英国文学指南》(The New Peli-can Guide to English Literature)是在1954年初次出版的《塘鹅英国文学指南》(The Peli-can Guide to English Literature)的基础上,经过十五次重印,于1982年大事增订修改后出版的一套新书。目前...《新塘鹅英国文学指南》(The New Peli-can Guide to English Literature)是在1954年初次出版的《塘鹅英国文学指南》(The Peli-can Guide to English Literature)的基础上,经过十五次重印,于1982年大事增订修改后出版的一套新书。目前,这套丛书在英国销路很畅。展开更多
文摘Rock bursts represent a formidable challenge in underground engineering,posing substantial risks to both infrastructure and human safety.These sudden and violent failures of rock masses are characterized by the rapid release of accumulated stress within the rock,leading to severe seismic events and structural damage.Therefore,the development of reliable prediction models for rock bursts is paramount to mitigating these hazards.This study aims to propose a tree-based model—a Light Gradient Boosting Machine(LightGBM)—to predict the intensity of rock bursts in underground engineering.322 actual rock burst cases are collected to constitute an exhaustive rock burst dataset,which serves to train the LightGBMmodel.Two population-basedmetaheuristic algorithms are used to optimize the hyperparameters of the LightGBM model.Finally,the sensitivity analysis is used to identify the predominant factors that may incur the occurrence of rock bursts.The results show that the population-based metaheuristic algorithms have a good ability to search out the optimal hyperparameters of the LightGBM model.The developed LightGBM model yields promising performance in predicting the intensity of rock bursts,with which accuracy on training and testing sets are 0.972 and 0.944,respectively.The sensitivity analysis discloses that the risk of occurring rock burst is significantly sensitive to three factors:uniaxial compressive strength(σc),stress concentration factor(SCF),and elastic strain energy index(Wet).Moreover,this study clarifies the particular impact of these three factors on the intensity of rock bursts through the partial dependence plot.
文摘Literature on spot-billed pelican has not been reviewed lately which could provide a critique of the emerging data. We have now chosen it as a key species through which we suggest a conservation action plan which will benefit several waterbird species. The information provided here is scholastic in nature and is meant to focus on aspects that require attention and help plan future work for applied conservation. All known information on this species is brought together in this review which will also provide an update of its biology. Notes on the breeding biology of the species first published in the Journal of the Bombay Natural History Society. So far, 380 works have appeared on the species; of these, 36 contain material reported in earlier works or appeared as papers subsequently. Most appeared as articles in journals, both national and regional, a few international journals, newsletters/bulletins （48.2%）, 4 dissertations, 76 reports and 6 popular science articles in magazines. This review on the species will provide an insight into different factors that can be weighed and combined while making a decision in investing resources in species conservation, i.e. importance of the species, level of threat and the time frame over which results are to be achieved.
文摘《新塘鹅英国文学指南》(The New Peli-can Guide to English Literature)是在1954年初次出版的《塘鹅英国文学指南》(The Peli-can Guide to English Literature)的基础上,经过十五次重印,于1982年大事增订修改后出版的一套新书。目前,这套丛书在英国销路很畅。
