随着深度伪造技术的发展,制作虚假人脸门槛降低。网络传播中图像压缩削弱伪造痕迹,导致传统检测方法性能下降。提出融合频率注意力机制和对比学习的智能检测方法,其中频率注意力模块捕获压缩环境下伪造频谱特征,对比学习优化特征空间分...随着深度伪造技术的发展,制作虚假人脸门槛降低。网络传播中图像压缩削弱伪造痕迹,导致传统检测方法性能下降。提出融合频率注意力机制和对比学习的智能检测方法,其中频率注意力模块捕获压缩环境下伪造频谱特征,对比学习优化特征空间分布,不确定度学习增强压缩噪声健壮性。实验显示,该方法在Celeb-DF数据集上曲线下的面积(Area Under Curve,AUC)达0.672,压缩图像检测AUC达0.584。展开更多
为实现海洋资源合理配置与环境保护协调发展,海洋功能区划将近岸海域划分成为不同功能区域,各功能区承受人类活动压力类型不同,科学评估不同功能区生态质量差异对于海洋空间资源可持续利用至关重要。于2020—2022年对鸭绿江口邻近海域...为实现海洋资源合理配置与环境保护协调发展,海洋功能区划将近岸海域划分成为不同功能区域,各功能区承受人类活动压力类型不同,科学评估不同功能区生态质量差异对于海洋空间资源可持续利用至关重要。于2020—2022年对鸭绿江口邻近海域的港口区、海洋保护区、捕捞区和航道区的底栖动物群落开展调查,并基于底栖动物的分类和功能性状构建了底栖完整性指数(Benthic Index of Biotic Integrity;B-IBI)评价指标。共采集大型底栖动物139种,其中环节动物63种、节肢动物39种、软体动物22种、棘皮动物6种、脊索动物3种,其他类群6种。不同海洋功能区的底栖动物的分类和功能性状呈现差异,港口区主要呈现耐污类群落特征,如更高比例的多毛类、二阶机会种、小型种、食沉积物者、管栖者等,然而海洋保护区、捕捞区和航道区主要呈现清洁类群落特征,如高比例的软体动物、中小型种、食浮游生物者、自由生活者以及游泳者等。基于底栖动物的分类和功能性状选择了41个候选指标,并通过分布范围、判别能力、冗余分析筛选出6个核心指标用于构建B-IBI评估体系。评估结果表明,鸭绿江口邻近海域的整体生态质量良好且呈现从港口区向其他海洋功能区升高的趋势,除港口区生态质量“较差”外,海洋保护区、捕捞区和航道区的生态质量均为“良好”,这表明港口区可能受到陆源污染、港口营运等人类活动的影响。相关性分析表明,B-IBI与NO_(3)^(-)-N,NH_(4)^(+)-N,PO_(4)^(3-)-P、Hg等污染因子呈显著负相关,暗示其可以反映周边入海河流和养殖排污对鸭绿江口生态质量的影响,证明了B-IBI用于评估鸭绿江口不同海洋功能区生态质量的有效性,可以反映污染物对海洋生态系统结构和功能的影响,为海洋功能区划评估提供依据。展开更多
Pitch is an excellent precursor for the production of hard carbon,with pre-oxidation crucial process in the fabrication.The structural changes in the different molecular components of pitch during thermochemical treat...Pitch is an excellent precursor for the production of hard carbon,with pre-oxidation crucial process in the fabrication.The structural changes in the different molecular components of pitch during thermochemical treatment are a key factor in determining the sodium-ion storage of pitchbased hard carbon anodes.We investigated the effects of the different molecular structures in the asphaltene precursor,including aromatic rings and aliphatic chains,on the sodiumion storage behavior of the resulting carbon.We found that polar oxygen functional groups limit the steric hindrance caused by the aromatic rings in pitch,and thus facilitate the introduction of cross-linked structures.During high-temperature carbonization,aromatic rings form a rigid carbon framework that prevents the rearrangement of ordered carbon layers,leading to a short-range disordered carbon structure and promotes the production of closed pores.For example,a material prepared from asphaltene,which contains a large number of oxygen-containing functional groups and macromolecular aromatic rings,using pre-oxidation at 300℃ and carbonization at 1200℃ had a reversible capacity of 316.7 mAh g^(−1) when used as the anode for sodium ion batteries.Our research provides a theoretical basis for the selection of raw materials for the development of high-quality pitch-based hard carbons.展开更多
文摘随着深度伪造技术的发展,制作虚假人脸门槛降低。网络传播中图像压缩削弱伪造痕迹,导致传统检测方法性能下降。提出融合频率注意力机制和对比学习的智能检测方法,其中频率注意力模块捕获压缩环境下伪造频谱特征,对比学习优化特征空间分布,不确定度学习增强压缩噪声健壮性。实验显示,该方法在Celeb-DF数据集上曲线下的面积(Area Under Curve,AUC)达0.672,压缩图像检测AUC达0.584。
文摘为实现海洋资源合理配置与环境保护协调发展,海洋功能区划将近岸海域划分成为不同功能区域,各功能区承受人类活动压力类型不同,科学评估不同功能区生态质量差异对于海洋空间资源可持续利用至关重要。于2020—2022年对鸭绿江口邻近海域的港口区、海洋保护区、捕捞区和航道区的底栖动物群落开展调查,并基于底栖动物的分类和功能性状构建了底栖完整性指数(Benthic Index of Biotic Integrity;B-IBI)评价指标。共采集大型底栖动物139种,其中环节动物63种、节肢动物39种、软体动物22种、棘皮动物6种、脊索动物3种,其他类群6种。不同海洋功能区的底栖动物的分类和功能性状呈现差异,港口区主要呈现耐污类群落特征,如更高比例的多毛类、二阶机会种、小型种、食沉积物者、管栖者等,然而海洋保护区、捕捞区和航道区主要呈现清洁类群落特征,如高比例的软体动物、中小型种、食浮游生物者、自由生活者以及游泳者等。基于底栖动物的分类和功能性状选择了41个候选指标,并通过分布范围、判别能力、冗余分析筛选出6个核心指标用于构建B-IBI评估体系。评估结果表明,鸭绿江口邻近海域的整体生态质量良好且呈现从港口区向其他海洋功能区升高的趋势,除港口区生态质量“较差”外,海洋保护区、捕捞区和航道区的生态质量均为“良好”,这表明港口区可能受到陆源污染、港口营运等人类活动的影响。相关性分析表明,B-IBI与NO_(3)^(-)-N,NH_(4)^(+)-N,PO_(4)^(3-)-P、Hg等污染因子呈显著负相关,暗示其可以反映周边入海河流和养殖排污对鸭绿江口生态质量的影响,证明了B-IBI用于评估鸭绿江口不同海洋功能区生态质量的有效性,可以反映污染物对海洋生态系统结构和功能的影响,为海洋功能区划评估提供依据。
文摘Pitch is an excellent precursor for the production of hard carbon,with pre-oxidation crucial process in the fabrication.The structural changes in the different molecular components of pitch during thermochemical treatment are a key factor in determining the sodium-ion storage of pitchbased hard carbon anodes.We investigated the effects of the different molecular structures in the asphaltene precursor,including aromatic rings and aliphatic chains,on the sodiumion storage behavior of the resulting carbon.We found that polar oxygen functional groups limit the steric hindrance caused by the aromatic rings in pitch,and thus facilitate the introduction of cross-linked structures.During high-temperature carbonization,aromatic rings form a rigid carbon framework that prevents the rearrangement of ordered carbon layers,leading to a short-range disordered carbon structure and promotes the production of closed pores.For example,a material prepared from asphaltene,which contains a large number of oxygen-containing functional groups and macromolecular aromatic rings,using pre-oxidation at 300℃ and carbonization at 1200℃ had a reversible capacity of 316.7 mAh g^(−1) when used as the anode for sodium ion batteries.Our research provides a theoretical basis for the selection of raw materials for the development of high-quality pitch-based hard carbons.
