检索结果-南通市图书馆

Evaluation of the glacial isostatic adjustment(GIA) models for Antarctica based on GPS vertical velocities

Science China Earth Sciences 2020年第4期63卷 575-590页

作者： Fei LI Chao MA Shengkai ZHANG jintao lei Weifeng HAO Qingchuan ZHANG Wenhao LI Chinese Antarctic Center of Surveying and Mapping Wuhan UniversityWuhan 430079China

Due to the scarcity of data, modeling the glacial isostatic adjustment(GIA) for Antarctica is more difficult than it is for the ancient ice sheet area in North America and Northern Europe. Large uncertainties are observed in existing GIA models for Antarctica. Modern space-based geodetic measurements provide checks and constraints for GIA models. The present-day uplift velocities of global positioning system(GPS) stations at 73 stations in Antarctica and adjacent regions from 1996 to 2014 have been estimated using GAMIT/GLOBK version 10.5 with a colored noise model. To easily analyze the effect of difference sources on the vertical velocities, and for easy comparison with both GIA model predictions and GPS results from Argus et al.(2014) and Thomas et al.(2011), seven sub-regions are divided. They are the northern Antarctic Peninsula, the Filchner-Ronne Ice Shelf, the Amundsen Sea coast, the Ross Ice Shelf, Mount Erebus, inland Southwest Antarctica and the East Antarctic coast,respectively. The results show that the fast uplift in the north Antarctic Peninsula and Pine Island Bay regions may be caused by the elastic response to snow and ice mass loss. The fast subsidence near Mount Erebus may be related to the activity of a magma body. The uplift or subsidence near the East Antarctic coast is very slow while the uplift for the rest regions is mainly caused by GIA. By analyzing the correlation and the associated weighted root mean square(WRMS) between the GIA predictions and the GPS velocities, we found that the ICE-6G_C(VM5a) model and the Geruo 13 model show the most consistency with our GPS results, while the W12a and IJ05_R2 series models show poor consistency with our GPS results. Although improved greatly in recent years, the GIA modeling in Antarctica still lags behind the modeling of the North American. Some GPS stations, for example the Bennett Nunatak station(BENN), have observed large discrepancies between GIA predictions and GPS velocities.Because of the large uncertainties in calculating elastic respo

关键词： Antarctica GPS Glacial isostatic adjustment Vertical velocity Uncertainty

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Self-powered stimuli responsive material for dual stimulation of heat and guest molecules

引用

Chinese Chemical Letters 2024年第2期35卷 590-593页

作者： jintao Men Ke Xu Taiting Sha lei He Yan Xu Jie Mu Tijian Yin Qiong Ye Jiangsu Key Laboratory for Science and Applications of Molecular Ferroelectrics and School of Chemistry and Chemical Engineering Southeast UniversityNanjing 211189China

Stimuli-responsive smart materials exhibit reverse chemical/physical changes in response to external stimuli and research on stimuli-responsive smart materials with self-powered properties is still uncultivated ground.Here,we report perovskite crystalline self-powered multiple stimuli-responsive materials triggered by chemical and thermal stimuli.[HMEP]PbI_(3)·(H_(2)O)(1;HMEP is a hydroxytris(1-methylethyl)phosphorus cation)crystallizes in a chiral space group P 21 at 293 K and has the piezoelectric reaction(d_(33)=10 pC/N and output voltage=1 V)of self-powered modes,this value is larger than the value of 3 pC/N for the classical piezoelectric material ZnO.Piezoelectric materials can generate energy due to mechanical deformation,and using thermal heating to lose water,[HMEP]PbI_(3)(2)can be obtained.2 crystallizes in the non-centrosymmetric space group,undergoes two reversible phase transitions at 243/255 K and 315/348 K,and shows second harmonic generation switching.Interestingly,2 can return to the hydrated form 1 after absorbing water.This work will lay the foundation for self-powered stimuli-responsive compounds and contribute to the construction of novel organic-inorganic hybrid materials with second harmonic generation switching.

关键词： Self-powered Dual stimulation reactive Phase transition SHG switch Organic-inorganic hybrid perovskite

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

山地城市内涝形成机理及管理策略研究

引用

重庆建筑 2024年第7期23卷 5-9页

作者：马念徐永新吴欢魏静婉李书钺雷锦涛韩璐明仆林同棪国际工程咨询<中国>有限公司重庆401121 西开普大学自然科学学院地球科学系南非开普敦7535

城市化改变了区域水文过程,涉及城市内涝的水安全问题成为城市普遍面临的挑战。该文以城市化水文效应和排水系统替代模型为基础研究了山地城市内涝机理和成因,在此基础上提出了城市内涝管理的总体策略。城市化后安全要求提高而人工的排... 详细信息

城市化改变了区域水文过程,涉及城市内涝的水安全问题成为城市普遍面临的挑战。该文以城市化水文效应和排水系统替代模型为基础研究了山地城市内涝机理和成因,在此基础上提出了城市内涝管理的总体策略。城市化后安全要求提高而人工的排水系统并不能完全替代原有的泄流通道,这一矛盾是城市内涝产生的根源;为管理等级有序的城市雨洪系统,需要根据系统构成、功能定位和等级制定与之相适应的技术标准,采取相适应的技术措施;雨洪管理需要防御性和适应性相结合,同时利用工程措施和非工程管理措施,并引入智慧管理手段以提高城市洪涝韧性。

关键词：山地城市城市内涝城市化水文效应排水系统替代模型形成机理内涝管理城市韧性

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Analysis of GPS Time Series Based on Spatio-temporal Filtering in Antarctic Peninsula

Analysis of GPS Time Series Based on Spatio-temporal Filteri...

引用

第九届中国卫星导航学术年会

作者： Wenhao Li Fei Li Shengkai Zhang jintao lei Qingchuan Zhang Chinese Antarctic Center of Surveying and Mapping

The high-accuracy GPS velocity field is one of effective approaches to study the regional crustal displacement, and can provide validations and constraints for GIA models. There are spatially and temporally correlated errors in GPS data. Applying a spatiotemporal filter can reduce these effects and improve the accuracy of GPS time series. To obtain high-accuracy GPS vertical velocities in Antarctic peninsula, a "regional filter" is used to remove the spatially correlated errors in the selected 6 GPS time series, and the classic autocorrelation function is used to mitigate the temporally correlated errors of each GPS time series. The result shows that the scatter of GPS time series is reduced significantly after spatiotemporal filtering, the reduction of maximum RMS can reach up to 41.82%, and mean RMS reduction is 35.44%.

关键词： Antarctic Peninsula GPS vertical velocities spatiotemporal filtering common mode errors

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Slope-climbing of cropland and its effects in China

引用

Journal of Mountain Science 2024年第8期 2754-2769页

作者： CHEN Wanxu XIE Youping YUAN jintao ZENG Jie YANG Liyan GU Tianci lei Fan Hubei Key Laboratory of Regional Ecology and Environmental Change School of Geography and Information Engineering China University of Geosciences Key Laboratory of Natural Resources Monitoring and Supervision in Southern Hilly Region Ministry of Natural Resources Yunnan Key Laboratory of Plateau Geographic Processes and Environmental Changes Faculty of Geography Yunnan Normal University

In recent decades, the spatio-temporal patterns of China's croplands have been reshaped by disturbances from anthropogenic activities, with complex changes in the topographic characteristics of croplands. Slope-climbing of croplands(SCCL) is an important issue that threatens sustainable agricultural development. While providing land with prominent location advantages, SCCL weakens the water and fertilizer retention capacity for cropland, intensifies various geological disasters, and adversely affects the ecological environment and food yield of these croplands. It is crucial to determine the spatiotemporal variation features and effects of SCCL in China to formulate more accurate cropland protection policies and to maintain food security; however, the current lack of relevant studies is detrimental for capturing trends in cropland resources and sustainable cropland use. In this study, we constructed a multiscale slope spectrum for cropland and total terrain to explore the spatial differences and trends of SCCL from a three-dimensional view. We evaluated the natural and socioeconomic effects of SCCL in China from multiple perspectives. Results indicate that the proportion of cropland with slopes below 2°, 5°, and 6° in China decreased by 0.43%, 0.47%, and 0.50% from 1980 to 2020, respectively. SCCL became apparent during 1980–1990 and 2010–2020, especially over the recent decade. The cropland climbing index(CCI) and upper limited slope change(ULSC) to measure the spatio-temporal pattern of SCCL were 0.99% and 1.17°, respectively, during 2010–2020. At the agricultural regional scale, the SCCL was also concentrated in 1980–1990 and 2010–2020, and it is more pronounced in the southern areas. The proportion of provinces and prefecture-level cities with highintensity SCCL during 1980–2020 were 87.10% and 49.73%, respectively. SCCL was comparatively more pronounced and broader from 2010 to 2020. During this period, 17.84% of prefecture-level cities had no SCCL, and the average CCI for all prefecture-level cities peaked

关键词：

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

一种基于LSTM-Blacklist的动态信任度证明机制

引用

武汉大学学报（理学版） 2023年第2期69卷 156-168页

作者：徐超雷锦涛陈勇南京审计大学计算机学院江苏南京211815

针对区块链网络中共识节点的恶意行为导致的区块链系统安全问题,提出一种基于LSTM(long short-term memory)-Blacklist的动态信任度证明机制(PoDT-LSTMB)。该动态信任度证明机制通过前向注意力机制的两层LSTM神经网络学习并分析参与共... 详细信息

针对区块链网络中共识节点的恶意行为导致的区块链系统安全问题,提出一种基于LSTM(long short-term memory)-Blacklist的动态信任度证明机制(PoDT-LSTMB)。该动态信任度证明机制通过前向注意力机制的两层LSTM神经网络学习并分析参与共识节点的行为数据,预测节点行为倾向。以节点信任度为基础构建黑名单,剔除低于信任度阈值的节点,提高全网节点的总体可信性。以正常区块上链率以及节点信任度的变化为主要评估指标,与信任度证明PoT(Proof of Trust)机制以及不带黑名单的PoDT-LSTM机制进行了对比实验。实验结果表明,基于前向注意力机制的两层LSTM神经网络结构准确率可达0.9151,本文提出的PoDT-LSTMB机制比PoT机制的正常区块上链率提高30%~33%。

关键词：区块链共识机制动态信任度长短期记忆黑名单机制

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Recent advances in cancer-associated fibroblast:Biomarkers,signaling pathways,and therapeutic opportunities

引用

Chinese Medical Journal 2024年第6期137卷 638-650页

作者： Donger Zhou lei Zheng Department of Hepatobiliary-Pancreatic Surgery The Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang 310009China Sidney Kimmel Comprehensive Cancer Center The Skip Viragh Pancreatic Cancer Center for Clinical Research and Careand The Bloomberg-Kimmel Institute for Immunotherapy at Johns Hopkins University School of MedicineBaltimoreMD 21287USA

Anti-cancer therapies usually focus on tumor cells,but non-tumor stromal components in the tumor microenvironment also play vital roles in tumor initiation and progression,which may be the prognostic factors and potential therapeutic targets.Cancer-associated fibroblasts(CAFs)are the essential component in the tumor environment,exhibiting high heterogeneity in their cell origin and phenotype with diverse functions that influence tumor angiogenesis,immune systems,and metabolism.Single-cell RNA sequencing and genetically engineered mouse models have increased our understanding of CAF diversity,and many subtypes have been defined.However,the precise functions of these subtypes need to be studied and validated.Studies of signaling pathways and epigenetic changes in CAFs facilitate understanding of the phenotypes of CAFs and the crosstalk between tumor cells and CAFs to provide potential therapeutic targets.Some clinical trials,including phase III trials targeting CAFs,have been performed recently.However,few of these trials have generated promising results,which indicates that the complexity of CAFs in the tumor microenvironment remains largely unknown,and in-depth investigations of CAFs should be performed.This review summarizes the research on CAFs,focusing on the heterogeneity of their phenotypes and functions,specific signaling pathways,and the therapeutic strategies involving CAFs.Additionally,we briefly discuss the current technologies commonly used in CAF studies and describe the challenges and future perspectives of CAF research.

关键词： Cancer-associated fibroblasts Tumor microenvironment Anti-cancer therapy Targeted therapy

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Metarelation2vec:A Metapath-Free Scalable Representation Learning Model for Heterogeneous Networks

引用

Tsinghua Science and Technology 2024年第2期29卷 553-575页

作者： lei Chen Yuan Li Yong lei Xingye Deng School of Information and Electrical Engineering Hunan University of Science and TechnologyXiangtan 411201China School of Computer Science and Engineering Hunan University of Science and TechnologyXiangtan 411201China

Metapaths with specific complex semantics are critical to learning diverse semantic and structural information of heterogeneous networks(HNs)for most of the existing representation learning models.However,any metapaths consisting of multiple,simple metarelations must be driven by domain experts.These sensitive,expensive,and limited metapaths severely reduce the flexibility and scalability of the existing models.A metapath-free,scalable representation learning model,called Metarelation2vec,is proposed for HNs with biased joint learning of all metarelations in a bid to address this problem.Specifically,a metarelation-aware,biased walk strategy is first designed to obtain better training samples by using autogenerating cooperation probabilities for all metarelations rather than using expert-given metapaths.Thereafter,grouped nodes by the type,a common and shallow skip-gram model is used to separately learn structural proximity for each node type.Next,grouped links by the type,a novel and shallow model is used to separately learn the semantic proximity for each link type.Finally,supervised by the cooperation probabilities of all meta-words,the biased training samples are thrown into the shallow models to jointly learn the structural and semantic information in the HNs,ensuring the accuracy and scalability of the models.Extensive experimental results on three tasks and four open datasets demonstrate the advantages of our proposed model.

关键词： metarelation random walk heterogeneous network metapath representation learning

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Structural energy storage composites based on modified carbon fiber electrode with metal-organic frame enhancing layered double hydroxide

引用

Nano Research 2024年第3期17卷 1552-1563页

作者： Jinrui Ye Zhongbao Wang Qin lei lei Sun Jinfeng Gu School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Tangshan Research Institute Beijing Institute of TechnologyTangshan 063000China School of Materials Science and Engineering Shenyang Jianzhu UniversityShenyang 110168China Department of Stomatology PLA Strategic Support Force Characteristic Medical CenterBeijing 100101China Beijing Electromechanical Engineering Research Institute Beijing 100074China

Structural energy storage composites present advantages in simultaneously achieving structural strength and electrochemical properties.Adoption of carbon fiber electrodes and resin structural electrolytes in energy storage composite poses challenges in maintaining good mechanical and electrochemical properties at reasonable cost and effort.Here,we report a simple method to fabricate structural supercapacitor using carbon fiber electrodes(modified by Ni-layered double hydroxide(Ni-LDH)and in-situ growth of Co-metal-organic framework(Co-MOF)in a two-step process denoted as Co-MOF/Ni-LDH@CF)and bicontinuous-phase epoxy resin-based structural electrolyte.Co-MOF/Ni-LDH@CF as electrode material exhibits improved specific capacity(42.45 F·g^(-1))and cycle performance(93.3%capacity retention after 1000 cycles)in a three-electrode system.The bicontinuous-phase epoxy resin-based structural electrolyte exhibits an ionic conductivity of 3.27×10^(-4) S·cm^(-1).The fabricated Co-MOF/Ni-LDH@CF/SPE-50 structural supercapacitor has an energy density of 3.21 Wh·kg^(-1) at a power density of 42.25 W·kg^(-1),whilst maintaining tensile strength and modulus of 334.6 MPa and 25.2 GPa.These results show practical potential of employing modified commercial carbon fiber electrodes and epoxy resin-based structural electrolytes in structural energy storage applications.

关键词： carbon fiber electrode structural electrolyte structural energy storage composites supercapacitor

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

DCVAE-adv:A Universal Adversarial Example Generation Method for White and Black Box Attacks

引用

Tsinghua Science and Technology 2024年第2期29卷 430-446页

作者： lei Xu Junhai Zhai College of Mathematics and Information Science Hebei UniversityBaoding 071002China

Deep neural network(DNN)has strong representation learning ability,but it is vulnerable and easy to be fooled by adversarial examples.In order to handle the vulnerability of DNN,many methods have been proposed.The general idea of existing methods is to reduce the chance of DNN models being fooled by observing some designed adversarial examples,which are generated by adding perturbations to the original images.In this paper,we propose a novel adversarial example generation method,called DCVAE-adv.Different from the existing methods,DCVAE-adv constructs adversarial examples by mixing both explicit and implicit perturbations without using original images.Furthermore,the proposed method can be applied to both white box and black box attacks.In addition,in the inference stage,the adversarial examples can be generated without loading the original images into memory,which greatly reduces the memory overhead.We compared DCVAE-adv with three most advanced adversarial attack algorithms:FGSM,AdvGAN,and AdvGAN++.The experimental results demonstrate that DCVAE-adv is superior to these state-of-the-art methods in terms of attack success rate and transfer ability for targeted attack.Our code is available at https://***/xzforeverlove/DCVAE-adv.

关键词： deep neural network adversarial examples white box attack black box attack robustness

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：