Intrusion detection is a predominant task that monitors and protects the network infrastructure.Therefore,many datasets have been published and investigated by researchers to analyze and understand the problem of intr...Intrusion detection is a predominant task that monitors and protects the network infrastructure.Therefore,many datasets have been published and investigated by researchers to analyze and understand the problem of intrusion prediction and detection.In particular,the Network Security Laboratory-Knowledge Discovery in Databases(NSL-KDD)is an extensively used benchmark dataset for evaluating intrusion detection systems(IDSs)as it incorporates various network traffic attacks.It is worth mentioning that a large number of studies have tackled the problem of intrusion detection using machine learning models,but the performance of these models often decreases when evaluated on new attacks.This has led to the utilization of deep learning techniques,which have showcased significant potential for processing large datasets and therefore improving detection accuracy.For that reason,this paper focuses on the role of stacking deep learning models,including convolution neural network(CNN)and deep neural network(DNN)for improving the intrusion detection rate of the NSL-KDD dataset.Each base model is trained on the NSL-KDD dataset to extract significant features.Once the base models have been trained,the stacking process proceeds to the second stage,where a simple meta-model has been trained on the predictions generated from the proposed base models.The combination of the predictions allows the meta-model to distinguish different classes of attacks and increase the detection rate.Our experimental evaluations using the NSL-KDD dataset have shown the efficacy of stacking deep learning models for intrusion detection.The performance of the ensemble of base models,combined with the meta-model,exceeds the performance of individual models.Our stacking model has attained an accuracy of 99%and an average F1-score of 93%for the multi-classification scenario.Besides,the training time of the proposed ensemble model is lower than the training time of benchmark techniques,demonstrating its efficiency and robustness.展开更多
Tanlu fault zone(TLFZ)is the largest active fault zone in eastern China.It is characterized by complex tectonic evolution and multiple faults and marks the boundary between the North and South China blocks.An indepth ...Tanlu fault zone(TLFZ)is the largest active fault zone in eastern China.It is characterized by complex tectonic evolution and multiple faults and marks the boundary between the North and South China blocks.An indepth understanding of the distinct crustal structures of both parts of the TLFZ will provide valuable insights into the lithospheric and crustal thinning in eastern China,extensive magmatism since the Mesozoic,and formation mechanisms of metallogenic belts along the Yangtze River.In this study,a two-layer H-κstacking approach was adopted to estimate the thicknesses of the sediment and crystalline crust as well as the corresponding vP/vS ratios based on high-quality teleseismic P-wave receiver functions recorded by permanent and temporary stations in and around the TLFZ.The geological units in the study region were delineated,especially the crustal structures beneath extensive sedimentary basins on both sides of the TLFZ.The following conclusions can be drawn:(1)The crustal thickness in and around the TLFZ greatly varies depending on the segment.In the northern segment,the crust is relatively thin beneath the eastern part of the Songliao Basin,a broad uplift of the Moho can be observed,and the Moho descends from south to north.The crust below the central and southern segments becomes thinner from west to east.The thickness of the crust is less than 30 km toward the eastern side of the boundary between the Jiangsu and Anhui provinces,that is,significantly thinner than in other areas.In terms of the vP/vS ratios,high anomalies were detected in the central-southern segments of the TLFZ,indicating the upwelling of deep mantle magma via deep faults.(2)Positive isostatic gravity anomalies were observed in the eastern part of the northern segment of the TLFZ and in the eastern part of the Suwan segment.The crustal thickness is smaller than that obtained from the Airy model of isostasy.This suggests that the lower crust in this area may have experienced intensive transformation processes,which may be related to crustal thinning(caused by crustal extension)and the strong uplift of the mantle in eastern China.The isostatic gravity anomalies between the eastern and western parts of the TLFZ indicate that the fault zone plays a dominant role in controlling the development of the deep crustal structure.(3)Significant crustal thinning was observed beneath the eastern part of the boundary between the Jiangsu and Anhui provinces in the southern segment of the TLFZ,suggesting that this area is prone to lithospheric thinning of the North China Craton.Due to the subduction,compression,and retreat of the Paleo-Pacific Plate during the Yanshanian Period as well as the dehydration of subducting oceanic crust(within subduction zones),the asthenosphere and oceanic crust in eastern China partially melted,resulting in mantle enrichment.The basic magma from the mantle is accumulated at the base of the crust,leading to magmatic underplating.In areas with weak topography toward the east of the TLFZ,magma rises to the upper crust and surface,resulting in the enrichment of multiple metal deposits in this area.展开更多
为了精准定位窃电行为,减小电力窃取给电力系统带来的经济损失,提出了一种基于熵权法Stacking(stacking based entropy,E_Stacking)集成学习的多分类窃电检测模型。首先基于用电量信息共线性的特点,使用方差膨胀因子(variance inflation...为了精准定位窃电行为,减小电力窃取给电力系统带来的经济损失,提出了一种基于熵权法Stacking(stacking based entropy,E_Stacking)集成学习的多分类窃电检测模型。首先基于用电量信息共线性的特点,使用方差膨胀因子(variance inflation factor,VIF)作为标准对数据降维,以降低数据复杂度。然后在模型训练时嵌入k折交叉验证,有效防止模型过拟合。该模型包含初级学习器和元学习器两层学习器,可以充分结合两层学习器的优点,将学习的互补特征和判别特征相结合,进一步提高检测性能。最后,使用爱尔兰数据集和部分加州大学欧文分校(University of California Irvine,UCI)数据集验证模型,结果优于目前几种常见的方法,证明该模型的有效性和稳定性。展开更多
A method to improve the low-velocity impact performance of composite laminate is proposed, and a multi-island genetic algorithm is used for the optimization of composite laminate stacking sequence under low-velocity i...A method to improve the low-velocity impact performance of composite laminate is proposed, and a multi-island genetic algorithm is used for the optimization of composite laminate stacking sequence under low-velocity impact loads based on a 2D dynamic impact finite element analysis. Low-velocity impact tests and compression-after impact(CAI) tests have been conducted to verify the effectiveness of optimization method. Experimental results show that the impact damage areas of the optimized laminate have been reduced by 42.1% compared to the baseline specimen, and the residual compression strength has been increased by 10.79%, from baseline specimen 156.97 MPa to optimized 173.91 MPa. The tests result shows that optimization method can effectively enhance the impact performances of the laminate.展开更多
Twisting the stacking of layered materials leads to rich new physics. A three-dimensional topological insulator film hosts two-dimensional gapless Dirac electrons on top and bottom surfaces, which, when the film is be...Twisting the stacking of layered materials leads to rich new physics. A three-dimensional topological insulator film hosts two-dimensional gapless Dirac electrons on top and bottom surfaces, which, when the film is below some critical thickness, will hybridize and open a gap in the surface state structure. The hybridization gap can be tuned by various parameters such as film thickness and inversion symmetry, according to the literature. The three-dimensional strong topological insulator Bi(Sb)Se(Te) family has layered structures composed of quintuple layers(QLs) stacked together by van der Waals interaction. Here we successfully grow twistedly stacked Sb_2Te_3 QLs and investigate the effect of twist angels on the hybridization gaps below the thickness limit. It is found that the hybridization gap can be tuned for films of three QLs, which may lead to quantum spin Hall states.Signatures of gap-closing are found in 3-QL films. The successful in situ application of this approach opens a new route to search for exotic physics in topological insulators.展开更多
By combining with the actual situation in the rural area,the practical technology of domestic wastewater treatment which had the wide popularization value was developed in the rural area of Taihu Basin.Moreover,the mu...By combining with the actual situation in the rural area,the practical technology of domestic wastewater treatment which had the wide popularization value was developed in the rural area of Taihu Basin.Moreover,the multi-soil-layering system was used to treat the concentrated rural domestic wastewater,and the demonstration project was established in Fenshui Village,Yixing,Jiangsu.The result showed that the infrastructure and operating cost of system was low,and the treatment effect was good.The average removal ratios of COD,NH+4-N,TN,TP and SS were respectively 70%,83%,59%,76% and 94%.The quality of yielding water could reach Grade A standard of Pollutant Emission Standards in Urban Wastewater Treatment Plant.展开更多
文摘Intrusion detection is a predominant task that monitors and protects the network infrastructure.Therefore,many datasets have been published and investigated by researchers to analyze and understand the problem of intrusion prediction and detection.In particular,the Network Security Laboratory-Knowledge Discovery in Databases(NSL-KDD)is an extensively used benchmark dataset for evaluating intrusion detection systems(IDSs)as it incorporates various network traffic attacks.It is worth mentioning that a large number of studies have tackled the problem of intrusion detection using machine learning models,but the performance of these models often decreases when evaluated on new attacks.This has led to the utilization of deep learning techniques,which have showcased significant potential for processing large datasets and therefore improving detection accuracy.For that reason,this paper focuses on the role of stacking deep learning models,including convolution neural network(CNN)and deep neural network(DNN)for improving the intrusion detection rate of the NSL-KDD dataset.Each base model is trained on the NSL-KDD dataset to extract significant features.Once the base models have been trained,the stacking process proceeds to the second stage,where a simple meta-model has been trained on the predictions generated from the proposed base models.The combination of the predictions allows the meta-model to distinguish different classes of attacks and increase the detection rate.Our experimental evaluations using the NSL-KDD dataset have shown the efficacy of stacking deep learning models for intrusion detection.The performance of the ensemble of base models,combined with the meta-model,exceeds the performance of individual models.Our stacking model has attained an accuracy of 99%and an average F1-score of 93%for the multi-classification scenario.Besides,the training time of the proposed ensemble model is lower than the training time of benchmark techniques,demonstrating its efficiency and robustness.
文摘Tanlu fault zone(TLFZ)is the largest active fault zone in eastern China.It is characterized by complex tectonic evolution and multiple faults and marks the boundary between the North and South China blocks.An indepth understanding of the distinct crustal structures of both parts of the TLFZ will provide valuable insights into the lithospheric and crustal thinning in eastern China,extensive magmatism since the Mesozoic,and formation mechanisms of metallogenic belts along the Yangtze River.In this study,a two-layer H-κstacking approach was adopted to estimate the thicknesses of the sediment and crystalline crust as well as the corresponding vP/vS ratios based on high-quality teleseismic P-wave receiver functions recorded by permanent and temporary stations in and around the TLFZ.The geological units in the study region were delineated,especially the crustal structures beneath extensive sedimentary basins on both sides of the TLFZ.The following conclusions can be drawn:(1)The crustal thickness in and around the TLFZ greatly varies depending on the segment.In the northern segment,the crust is relatively thin beneath the eastern part of the Songliao Basin,a broad uplift of the Moho can be observed,and the Moho descends from south to north.The crust below the central and southern segments becomes thinner from west to east.The thickness of the crust is less than 30 km toward the eastern side of the boundary between the Jiangsu and Anhui provinces,that is,significantly thinner than in other areas.In terms of the vP/vS ratios,high anomalies were detected in the central-southern segments of the TLFZ,indicating the upwelling of deep mantle magma via deep faults.(2)Positive isostatic gravity anomalies were observed in the eastern part of the northern segment of the TLFZ and in the eastern part of the Suwan segment.The crustal thickness is smaller than that obtained from the Airy model of isostasy.This suggests that the lower crust in this area may have experienced intensive transformation processes,which may be related to crustal thinning(caused by crustal extension)and the strong uplift of the mantle in eastern China.The isostatic gravity anomalies between the eastern and western parts of the TLFZ indicate that the fault zone plays a dominant role in controlling the development of the deep crustal structure.(3)Significant crustal thinning was observed beneath the eastern part of the boundary between the Jiangsu and Anhui provinces in the southern segment of the TLFZ,suggesting that this area is prone to lithospheric thinning of the North China Craton.Due to the subduction,compression,and retreat of the Paleo-Pacific Plate during the Yanshanian Period as well as the dehydration of subducting oceanic crust(within subduction zones),the asthenosphere and oceanic crust in eastern China partially melted,resulting in mantle enrichment.The basic magma from the mantle is accumulated at the base of the crust,leading to magmatic underplating.In areas with weak topography toward the east of the TLFZ,magma rises to the upper crust and surface,resulting in the enrichment of multiple metal deposits in this area.
文摘为了精准定位窃电行为,减小电力窃取给电力系统带来的经济损失,提出了一种基于熵权法Stacking(stacking based entropy,E_Stacking)集成学习的多分类窃电检测模型。首先基于用电量信息共线性的特点,使用方差膨胀因子(variance inflation factor,VIF)作为标准对数据降维,以降低数据复杂度。然后在模型训练时嵌入k折交叉验证,有效防止模型过拟合。该模型包含初级学习器和元学习器两层学习器,可以充分结合两层学习器的优点,将学习的互补特征和判别特征相结合,进一步提高检测性能。最后,使用爱尔兰数据集和部分加州大学欧文分校(University of California Irvine,UCI)数据集验证模型,结果优于目前几种常见的方法,证明该模型的有效性和稳定性。
基金Funded by the National Natural Science Foundation of China(No.51275393)the Fundamental Research Funds for the Central Universities(No.xjj2017160)
文摘A method to improve the low-velocity impact performance of composite laminate is proposed, and a multi-island genetic algorithm is used for the optimization of composite laminate stacking sequence under low-velocity impact loads based on a 2D dynamic impact finite element analysis. Low-velocity impact tests and compression-after impact(CAI) tests have been conducted to verify the effectiveness of optimization method. Experimental results show that the impact damage areas of the optimized laminate have been reduced by 42.1% compared to the baseline specimen, and the residual compression strength has been increased by 10.79%, from baseline specimen 156.97 MPa to optimized 173.91 MPa. The tests result shows that optimization method can effectively enhance the impact performances of the laminate.
基金Supported by the National Natural Science Foundation of China (Grant Nos.61804056 and 92065102)。
文摘Twisting the stacking of layered materials leads to rich new physics. A three-dimensional topological insulator film hosts two-dimensional gapless Dirac electrons on top and bottom surfaces, which, when the film is below some critical thickness, will hybridize and open a gap in the surface state structure. The hybridization gap can be tuned by various parameters such as film thickness and inversion symmetry, according to the literature. The three-dimensional strong topological insulator Bi(Sb)Se(Te) family has layered structures composed of quintuple layers(QLs) stacked together by van der Waals interaction. Here we successfully grow twistedly stacked Sb_2Te_3 QLs and investigate the effect of twist angels on the hybridization gaps below the thickness limit. It is found that the hybridization gap can be tuned for films of three QLs, which may lead to quantum spin Hall states.Signatures of gap-closing are found in 3-QL films. The successful in situ application of this approach opens a new route to search for exotic physics in topological insulators.
基金Supported by The Important Special Item of National Water Body Pollution Control and Treatment Science Technology(2009ZX07528005)~~
文摘By combining with the actual situation in the rural area,the practical technology of domestic wastewater treatment which had the wide popularization value was developed in the rural area of Taihu Basin.Moreover,the multi-soil-layering system was used to treat the concentrated rural domestic wastewater,and the demonstration project was established in Fenshui Village,Yixing,Jiangsu.The result showed that the infrastructure and operating cost of system was low,and the treatment effect was good.The average removal ratios of COD,NH+4-N,TN,TP and SS were respectively 70%,83%,59%,76% and 94%.The quality of yielding water could reach Grade A standard of Pollutant Emission Standards in Urban Wastewater Treatment Plant.