检索结果-南通市图书馆

Spatiotemporal optical properties of dissolved organic matter in a sluice-controlled coastal plain river with both salinity and trophic gradients

引用

Journal of Environmental Sciences 2023年第7期129卷 1-15页

作者： Yu Liu yucheng hu Chengxun Yu Yuqi Gao Zhenying Liu Khan M.G.Mostofa Siliang Li Yumei hu Guanghui Yu School of Earth System Science Institute of Surface-Earth System ScienceTianjin UniversityTianjin 300072China Tianjin Hydraulic Science Research Institute Tianjin 300061China School of Environmental Science and Safety Engineering Tianjin University of TechnologyTianjin 300191China School of Mathematics Tianjin UniversityTianjin 300072China

Due to the combined effect of sluices and sea tide,the sluice-controlled coastal plain river would be characterized by both trophic state and salinity gradients,affecting the spatiotemporal optical properties of dissolved organicmatter(DOM).In this study,we investigated the spatiotemporal variation of water quality parameters and optical properties of DOM in the Haihe River,a representative sluice-controlled coastal plain river in Tianjin,China.A significant salinity gradient and four trophic states were observed in the water body of the Haihe River.Two humic-and one protein-like substances were identified from the DOM by the three-dimensional fluorescence spectra combined with the parallel factor(PARAFAC)analysis.Pearson’s correlation analysis and redundancy analysis(RDA)showed that the salinity significantly affected the abundance of chromophoric DOM(CDOM)but did not cause significant changes in the fluorescence optical characteristics.In addition,the effect of Trophic state index(TSI)on the CDOM abundance was greater than that on the fluorescence intensity of fluorescent dissolved organic matter(FDOM).In the water body with both salinity and trophic state gradients,TSI posed a greater influence than salinity on the CDOM abundance.Our results fill the research gap in spatiotemporal DOM characteristics and water quality variation in water bodies with both salinity and trophic state gradients.These results are beneficial for clarifying the joint influence of saline intrusion and sluices on the DOM characteristics and water quality in sluice-controlled coastal plain rivers.

关键词： Dissolved organic matter Optical characteristics Trophic state index Salinity gradient Haihe River Sluice-controlled coastal plain river

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

Water quality characteristics and assessment of Yongding New River by improved comprehensive water quality identification index based on game theory

引用

Journal of Environmental Sciences 2021年第6期33卷 40-52页

作者： Yu Liu yucheng hu Yumei hu Yuqi Gao Zhenying Liu School of Earth System Science Institute of Surface-Earth System ScienceTianjin UniversityTianjin 300072China Tianjin Hydraulic Science Research Institute Tianjin 300061China School of Mathematics Tianjin UniversityTianjin 300072China School of Environmental Science and Safety Engineering Tianjin University of TechnologyTianjin 300191China

The Yongding New River is essential for the water supplies of Tianjin.To date,there is no comprehensive report that assesses the year-round water quality of the Yongding New River Main stream.Moreover,little attention has been given to determining a combined weight for improving the traditional comprehensive water quality identification index(ICWQII)by the game theory.Seven water quality parameters were investigated monthly along the main stream of the Yongding New River from May 2018 to April 2019.Organic contaminants and nitrogen pollution were mainly caused by point sources pollution,and the total phosphorus mainly by non-point source pollution.Dramatic spatio-temporal variations of water quality parameters were jointly caused by different pollutant sources and hydrometeorological factors.In terms of this study,an improved comprehensive water quality identification index(ICWQII)based on entropy weight or variation coefficient and traditional CWQII underestimated the water qualities,and an ICWQII based on the superstandard multiple method overvalued the assessments.By contrast,water qualities assessments done with an ICWQII based on the game theory matched perfectly with the practical situation.The ICWQII based on game theory proposed in this study takes into account not only the degree of disorder and variation of water quality data,but also the influence of standard-exceeded pollution indicators,whose results are relatively reasonable.All findings and the ICWQII based on game theory can provide scientific support for decisions related to the water environment management of the Yongding New River and other waters.

关键词： Water quality assessment Improved comprehensive water quality identification index Game theory Combined weight Spatio-temporal variation Yongding New River

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

基于MEFD-小波阈值降噪的舰船电场特征提取

引用

华中科技大学学报（自然科学版） 2024年第4期52卷 88-93页

作者：胡育诚王向军汪石川海军工程大学电气工程学院湖北武汉430033

为实现低信噪比情况下的舰船轴频电场特征提取,提出一种基于MEFD-小波阈值的特征提取方法.首先采用引入自回归滑动平均模型(ARMA)的改进经验傅里叶分解(MEFD)分解含噪信号;然后采用L2范数筛选出有效信息分量;最后对后续的信号采用小波... 详细信息

为实现低信噪比情况下的舰船轴频电场特征提取,提出一种基于MEFD-小波阈值的特征提取方法.首先采用引入自回归滑动平均模型(ARMA)的改进经验傅里叶分解(MEFD)分解含噪信号;然后采用L2范数筛选出有效信息分量;最后对后续的信号采用小波阈值降噪进行处理.为验证所提方法的有效性,采用仿真信号与船模实测信号进行对比实验.结果表明:本文方法对环境噪声干扰具有鲁棒性,在船模实验2B距离下的提取结果正交性指数为0.0015,相似性指数为0.4503,具有更好的特征提取效果,能实现更远距离的电场信号检测,为后续的电场特性分析及应用打下良好基础.

关键词：轴频电场改进经验傅里叶分解小波阈值去噪 L2范数特征提取

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

CHEBYSHEV METHODS WITH DISCRETE NOISE:THE T-ROCK METHODS

引用

Journal of Computational Mathematics 2010年第2期28卷 195-217页

作者： Assyr Abdulle yucheng hu Tiejun Li Mathematics Section Ecole Polytechnique Federale de Lausanne CH-1015 Lausanne Switzerland Laboratory of Mathematics and Applied Mathematics and School of Mathematical Sciences Peking University Beijing 100871 China

Stabilized or Chebyshev explicit methods have been widely used in the past to solve stiff ordinary differential equations. Making use of special properties of Chebyshev-like polynomials, these methods have favorable stability properties compared to standard explicit methods while remaining explicit. A new class of such methods, called ROCK, introduced in [Numer. Math., 90, 1-18, 2001] has recently been extended to stiff stochastic differential equations under the name S-ROCK [C. R. Acad. Sci. Paris, 345（10）, 2007 and Commun. Math. Sci, 6（4）, 2008]. In this paper we discuss the extension of the S-ROCK methods to systems with discrete noise and propose a new class of methods for such problems, the τ-ROCK methods. One motivation for such methods is the simulation of multi-scale or stiff chemical kinetic systems and such systems are the focus of this paper, but our new methods could potentially be interesting for other stiff systems with discrete noise. Two versions of the τ-ROCK methods are discussed and their stability behavior is analyzed on a test problem. Compared to the τ-leaping method, a significant speed-up can be achieved for some stiff kinetic systems. The behavior of the proposed methods are tested on several numerical experiments.

关键词： Stiff stochastic differential equations Runge-Kutta Chebyshev methods Chem-ical reaction systems tau-leaping method

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

Boosted Hybrid Method for Solving Chemical Reaction Systems with Multiple Scales in Time and Population Size

引用

Communications in Computational Physics 2012年第9期12卷 981-1005页

作者： yucheng hu Assyr Abdulle Tiejun Li Laboratory of Mathematics and Applied Mathematics and School of Mathematical Sciences Peking UniversityBeijing 100871China Mathematics Section Ecole Polytechnique Federale de LausanneCH-1015 LausanneSwitzerland

A new algorithm,called boosted hybrid method,is proposed for the simulation of chemical reaction systems with scale-separation in time and disparity in species population.For such stiff systems,the algorithm can automatically identify scale-separation in time and slow down the fast reactions while maintaining a good approximation to the original effective dynamics.This technique is called boosting.As disparity in species population may still exist in the boosted system,we propose a hybrid strategy based on coarse-graining methods,such as the tau-leaping method,to accelerate the reactions among large population species.The combination of the boosting strategy and the hybrid method allow for an efficient and adaptive simulation of complex chemical reactions.The new method does not need a priori knowledge of the system and can also be used for systems with hierarchical multiple time scales.Numerical experiments illustrate the versatility and efficiency of the method.

关键词： Chemical reaction multiscale boosting hybrid method

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

天津市乡村旅游高质量发展研究

引用

北方经贸 2024年第4期 147-152页

作者：范留洋胡宇橙天津商业大学管理学院天津300133

乡村旅游是助力乡村振兴的新兴产业之一,在我国社会主义新农村建设发展中具有重要作用。为带动县乡消费和促进旅游业可持续发展提供助力,在梳理乡村旅游概念、乡村旅游高质量发展背景和乡村旅游高质量发展的研究内容的基础上,对天津市... 详细信息

乡村旅游是助力乡村振兴的新兴产业之一,在我国社会主义新农村建设发展中具有重要作用。为带动县乡消费和促进旅游业可持续发展提供助力,在梳理乡村旅游概念、乡村旅游高质量发展背景和乡村旅游高质量发展的研究内容的基础上,对天津市乡村旅游的现状以及存在的问题进行分析,并从发展规划、产业融合、基础设施、人才供给四个方面提出相关建议,以期对天津市乡村旅游高质量发展有所裨益。

关键词：乡村旅游高质量发展天津市

来源：

维普期刊数据库

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

考虑外平台影响下海上风机单桩基础结构地震动力响应分析

引用

水力发电 2024年第1期50卷 82-89,102页

作者：侯法垒姚莫凡胡雨承张永赵杨山能新能源(东营)有限公司山东东营250014 中国电建集团华东勘测设计研究院有限公司浙江杭州311100 浙江华东工程咨询有限公司浙江杭州311100 水资源工程与调度全国重点实验室(武汉大学) 湖北武汉430072

随着海上风机单桩基础的广泛应用,分析单桩基础及其附属结构在地震荷载作用下的动力响应具有重要意义。为此,采用ABAQUS有限元分析软件建立了单桩-外平台整体结构模型,采用粘弹性边界法模拟地震荷载施加,分析了地震作用下整体结构的动... 详细信息

随着海上风机单桩基础的广泛应用,分析单桩基础及其附属结构在地震荷载作用下的动力响应具有重要意义。为此,采用ABAQUS有限元分析软件建立了单桩-外平台整体结构模型,采用粘弹性边界法模拟地震荷载施加,分析了地震作用下整体结构的动力响应情况,并探究了外平台对单桩自振特性及响应的影响。研究结果表明:地震荷载作用下,单桩-外平台整体结构的应力最大值出现在工作平台和支撑杆连接处,水平位移最大值出现在顶部工作平台上,牛腿应力和位移相对较小;外平台对单桩的自振频率具有减缓增大的作用,可降低基频,且会小幅度增大单桩基础应力,对单桩基础的稳定工作不会产生较大影响。

关键词：海上风机单桩基础外平台地震动力响应有限元分析

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

Influence of human Activity Intensity on Habitat Quality in Hainan Tropical Rainforest National Park,China

引用

Chinese Geographical Science 2024年第3期34卷 519-532页

作者： HAN Nianlong YU Miao JIA Peihong ZHANG yucheng hu Ke School of Geography and Tourism Huizhou UniversityHuizhou 516007China School of Public Administration Hainan Uni-versityHaikou 570228China Department of Land Surveying and Geo-Informatics The Hong Kong Polytechnic UniversityHong KongChina School of Geographic Sciences and Remote Sensing Guangzhou UniversityGuangzhou 510006China School of Public Administration Nanjing Agricultural UniversityNanjing 210095China

Due to long-term human activity interference,the Hainan Tropical Rainforest National Park(HTRNP)of China has experienced ecological problems such as habitat fragmentation and biodiversity loss,and with the expanding scope and intensity of human activity impact,the regional ecological security is facing serious challenges.A scientific assessment of the interrelationship between human activity intensity and habitat quality in the HTRNP is a prerequisite for achieving effective management of ecological disturbances caused by human activities and can also provide scientific strategies for the sustainable development of the region.Based on the land use change data in 2000,2010,and 2020,the spatial and temporal variations and the relationship between habitat quality(HQ)and human activity intensity(HAI)in the HTRNP were explored using the integrated valuation of ecosystem services and trade-offs(InVEST)model.System dynamics and land use simulation models were also combined to conduct multi-scenario simulations of their relationships.The results showed that during 2000–2020,the habitat quality of the HTRNP improved,the intensity of human activities decreased each year,and there was a negative correlation between the two.Second,the system dynamic model could be well coupled with the land use simulation model by combining socio-economic and natural factors.The simulation scenarios of the coupling model showed that the harmonious development(HD)scenario is effective in curbing the increasing trend of human activity intensity and decreasing trend of habitat quality,with a weaker trade-off between the two compared with the baseline development(BD)and investment priority oriented(IPO)scenarios.To maintain the authenticity and integrity of the HTRNP,effective measures such as ecological corridor construction,ecological restoration,and the implementation of ecological compensation policies need to be strengthened.

关键词： human activity intensity(HAI) habitat quality(HQ) bivariate spatial autocorrelation system dynamics model integrated valuation of ecosystem services and trade-offs(InVEST)model Hainan Tropical Rainforest National Park(HTRNP)of China

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

基于影像组学的CT和MRI诊断肝癌射频消融术后复发预测中的比较研究

引用

影像科学与光化学 2024年第3期42卷 177-186页

作者：陈飞胡羽澄吴桐郑凯文张雪君郭丽天津医科大学天津300203

目的:旨在评估CT和MRI影像在诊断肝癌射频消融术后复发情况的有效性。方法:通过对27名肝癌患者进行射频消融术后的31个结节进行回顾性分析,本文对增强CT和MRI T1序列延迟期图像提取影像组学特征,并进行数据处理和特征选择。采用影像组... 详细信息

目的:旨在评估CT和MRI影像在诊断肝癌射频消融术后复发情况的有效性。方法:通过对27名肝癌患者进行射频消融术后的31个结节进行回顾性分析,本文对增强CT和MRI T1序列延迟期图像提取影像组学特征,并进行数据处理和特征选择。采用影像组学方法,结合多种机器学习模型,对增强CT和MRI T1序列图像进行分析。通过准确率、F1值、精确率、召回率/敏感度、特异度和ROC曲线下面积(AUC)对模型进行评估。结果:CT图像的1334个组学特征中,经过删除和特征降维,最终保留6个关键特征。而MRI图像则从相同数量的特征中保留10个关键特征。这一对比结果显示出CT在特征简洁性上的优势。在测试集上,随机森林模型表现最佳,CT图像的ROC曲线下面积为0.92,而MRI图像为0.83。结论:增强CT和MRI在对于肝癌射频消融术后患者复发情况的诊断均具有重要价值。在影像组学特征中CT图像相较于MRI T1序列对肝癌射频消融术后复发情况的诊断有相对更高的准确率和应用价值。

关键词：肝癌射频消融诊断影像组学机器学习

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

Generation of Quantum-dot Photon Emission in h-BN via Local Strain Engineering

引用

Journal of Wuhan University of Technology(Materials Science) 2023年第4期38卷 803-806页

作者：马亮胡玉成 ZHOU Zeyi Zhu Bo ZHENG Wenjie 张瑞 School of Physics and Optoelectronics Engineering Anhui UniversityHefei230039China

We reported a low-cost and easy-to-make method to effectively generate quantum dot(QD)states in 2D hBN films for quantum emissions at room temperature by utilizing silica nanospheres,in comparison with the sophisticated nanofabrication method reported in previous studies.The QDs created in 2D hBN films using silica nanospheres exhibit pronounced photon emissions with a good photo-stability in air,a narrow distribution of the emission peaks within the range of 580-620 nm,and a directional emission pattern,behaving as a single electric dipole.Our work develops the method of controllable fabrication of quantum emitters in 2D materials by using nano materials and structures.

关键词： hexagonal boron nitride silica nanospheres local strain quantum dots quantum emission

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

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：