检索结果-南通市图书馆

Changes in Surface Energy Partitioning in china over the Past Three Decades

Advances in Atmospheric Sciences 2017年第5期34卷 635-649页

作者： Yitian QIAN Pang-chi HSU chi-han cheng Key Laboratory of Meteorological Disaster of Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of lnformation Science and Technology Nanjing Jiangsu 210044 China Applied Hydrometeorological Research Institute Nanjing University of Information Science and Technology Nanjing Jiangsu 210044 China

Surface energy balance and the partitioning of sensible heat flux(SHF) and latent heat flux(LHF) play key roles in land–atmosphere feedback. However,the lack of long-term observations of surface energy fluxes,not to mention spatially extensive ones,limits our understanding of how the surface energy distribution has responded to a warming climate over recent decades(1979–2009) at the national scale in china. Using four state-of-the-art reanalysis products with long-term surface energy outputs,we identified robust changes in surface energy partitioning,defined by the Bowen ratio(BR = SHF/LHF),over different climate regimes in china. Over the past three decades,the net radiation showed an increasing trend over almost the whole of china. The increase in available radiative energy flux,however,was balanced by differential partitioning of surface turbulent fluxes,determined by local hydrological conditions. In semi-arid areas,such as Northeast china,the radiative energy was transferred largely into SHF. A severe deficiency in near-surface and soil moistures led to a significant decreasing trend in LHF. The combined effect of increased SHF and decreased LHF resulted in significant upward trends in the BR and surface warming over Northeast china. In contrast,in the wet monsoon regions,such as southern china,increased downward net radiation favored a rise in LHF rather than in SHF,leading to a significant decreasing trend in the BR. Meanwhile,the increased LHF partly cancelled out the surface warming. The warming trend in southern china was smaller than that in Northeast china. In addition to impacts on heat-related events,the changes in the BR also reflected recent cases of extreme drought in china. Our results indicate that information regarding the BR may be valuable for drought monitoring,especially in regions prone to such conditions.

关键词： surface energy partitioning Bowen ratio climate change long-term trend

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

Honeycomb-like biochar framework coupled with Fe_(3)O_(4)/FeS nanoparticles as efficient heterogeneous Fenton catalyst for phenol degradation

引用

Journal of Environmental Sciences 2024年第2期136卷 390-399页

作者： Aihua cheng Yi He Xiaohe Liu chi He Department of Environmental Engineering College of Geology and EnvironmentXi’an University of Science and TechnologyXi’an 710054China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an 710049China National Engineering Laboratory for VOCs Pollution Control Material and Technology University of Chinese Academy of SciencesBeijing 101408China

Achieving an efficient and stable heterogeneous Fenton reaction over a wide pH range is of great significance for wastewater ***,a pollen-derived biochar catalyst with a unique honeycomb-like structure,coupled with the dispersion of magnetic Fe_(3)O_(4)/FeS(Fe/S)nanoparticles,was synthesized by simple impregnation precursor,followed by *** prepared Fe/S-biochar catalyst demonstrated outstanding phenol degradation efficiency across a wide pH range,with 98%of which eliminated even under neutral conditions(pH 7.0).The high catalytic activity was due to the multilevel porous structure of pollenderived biochar provided enough active sites and allowed for better electron transfer,then increases oxidation ability to promote the ***,the acid microenvironment formed by SO_(4)^(2-)group from Fe/S composite extended the pH range for Fenton reaction,and S^(2-)facilitated the conversion of≡Fe^(3+)to≡Fe^(2+),resulting in remarkable degradation ***,biochar can effectively promote cycling stability by limiting Fe *** work may provide a general strategy for designing 3D framework biochar-based Fe/S catalysts with excellent performance for heterogeneous Fenton reactions.

关键词： Biomass Biochar Fenton reaction Fe_(3)O_(4)/FeS(Fe/S) Phenol degradation

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

Prediction and Output Estimation of Pattern Moving in Non-Newtonian Mechanical Systems Based on Probability Density Evolution

引用

Computer Modeling in Engineering & Sciences 2024年第4期139卷 515-536页

作者： cheng han Zhengguang Xu School of Automation and Electrical Engineering University of Science and Technology BeijingBeijing100083China Key Laboratory of Knowledge Automation for Industrial Processes University of Science and Technology BeijingBeijing100083China

A prediction framework based on the evolution of pattern motion probability density is proposed for the output prediction and estimation problem of non-Newtonian mechanical systems,assuming that the system satisfies the generalized Lipschitz *** a complex nonlinear system primarily governed by statistical laws rather than Newtonian mechanics,the output of non-Newtonian mechanics systems is difficult to describe through deterministic variables such as state variables,which poses difficulties in predicting and estimating the system’s *** this article,the temporal variation of the system is described by constructing pattern category variables,which are non-deterministic *** pattern category variables have statistical attributes but not operational attributes,operational attributes are assigned to them by posterior probability density,and a method for analyzing their motion laws using probability density evolution is ***,a data-driven form of pattern motion probabilistic density evolution prediction method is designed by combining pseudo partial derivative(PPD),achieving prediction of the probability density satisfying the system’s output *** on this,the final prediction estimation of the system’s output value is realized by minimum variance unbiased ***,a corresponding PPD estimation algorithm is designed using an extended state observer(ESO)to estimate the parameters to be estimated in the proposed prediction *** effectiveness of the parameter estimation algorithm and prediction method is demonstrated through theoretical analysis,and the accuracy of the algorithm is verified by two numerical simulation examples.

关键词： Non-newtonian mechanical systems prediction and estimation pattern moving probability density evolution pseudo partial derivative

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

Reactor field reconstruction from sparse and movable sensors using Voronoi tessellation-assisted convolutional neural networks

引用

Nuclear Science and Techniques 2024年第5期35卷 173-185页

作者： He-Lin Gong han Li Dunhui Xiao Sibo cheng Paris Elite Institute of Technology Shanghai Jiao Tong UniversityShanghai 200240China School of Mathematical Sciences Tongji UniversityShanghai 200092China Department of Computing Data Science InstituteImperial College LondonLondon SW72AZUK

The aging of operational reactors leads to increased mechanical vibrations in the reactor *** vibration of the incore sensors near their nominal locations is a new problem for neutronic field *** field-reconstruction methods fail to handle spatially moving *** this study,we propose a Voronoi tessellation technique in combination with convolutional neural networks to handle this *** from movable in-core sensors were projected onto the same global field structure using Voronoi tessellation,holding the magnitude and location information of the *** convolutional neural networks were used to learn maps from observations to the global *** proposed method reconstructed multi-physics fields(including fast flux,thermal flux,and power rate)using observations from a single field(such as thermal flux).Numerical tests based on the IAEA benchmark demonstrated the potential of the proposed method in practical engineering applications,particularly within an amplitude of 5 cm around the nominal locations,which led to average relative errors below 5% and 10% in the L_(2) and L_(∞)norms,respectively.

关键词： Voronoi tessellation Field reconstruction Nuclear reactors Reactor physics On-line monitoring

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

Monocular Distance Estimated Based on PTZ Camera

引用

Computers, Materials & Continua 2024年第5期79卷 3417-3433页

作者： Qirui Zhong Xiaogang cheng Yuxin Song han Wang Bell Honors School Nanjing University of Posts and Telecommunications Nanjing210003China College of Telecommunications and Information Engineering Nanjing University of Posts and TelecommunicationsNanjing210003China College of Automation and College of Artificial Intelligence Nanjing University of Posts and TelecommunicationsNanjing210003China

This paper introduces an intelligent computational approach for extracting salient objects fromimages and estimatingtheir distance information with PTZ (Pan-Tilt-Zoom) cameras. PTZ cameras have found wide applications innumerous public places, serving various purposes such as public securitymanagement, natural disastermonitoring,and crisis alarms, particularly with the rapid development of Artificial Intelligence and global infrastructuralprojects. In this paper, we combine Gauss optical principles with the PTZ camera’s capabilities of horizontal andpitch rotation, as well as optical zoom, to estimate the distance of the *** present a novel monocular objectdistance estimation model based on the Focal Length-Target Pixel Size (FLTPS) relationship, achieving an accuracyrate of over 95% for objects within a 5 km range. The salient object extraction is achieved through a simplifiedconvolution kernel and the utilization of the object’s RGB features, which offer significantly faster computingspeeds compared to Convolutional Neural Networks (CNNs). Additionally, we introduce the dark channel beforethe fog removal algorithm, resulting in a 20 dB increase in image definition, which significantly benefits distanceestimation. Our system offers the advantages of stability and low device load, making it an asset for public securityaffairs and providing a reference point for future developments in surveillance hardware.

关键词： Public security location information PTZ camera image processing

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

Spatio-Temporal Service Analysis in Multi-Layer Non-Terrestrial Networks

引用

Journal of Communications and Information Networks 2024年第1期9卷 43-55页

作者： Qian Chen Weixiao Meng Shuai han cheng Li School of Electronics and Information Engineering Harbin Institute of TechnologyHarbin 150001China School of Engineering Science Simon Fraser UniversityBurnabyBC V5A 1S6Canada Department of Electrical and Computer Engineering Memorial UniversitySt.John’sNL A1B 3X5Canada

In the advent of the 6G era, non-terrestrial networks (NTN) with expansive coverage are being increasingly recognized as a vital supplement to cellular networks for facilitating seamless communication. The intricate interplay between network performance and service quality necessitates a thorough investigation into the modeling and analysis of services for efficient construction of *** studies on service analysis, predominantly focused on terrestrial networks,fall short in addressing the unique challenges posed by NTN,particularly those related to platform distribution and antenna gain modeling. This deficiency in research,coupled with the varying preferences of users for different network types, forms the basis of this study. This paper explores the spatio-temporal characteristics of services within a multi-layered NTN *** this context,the spatial distribution of the platforms is modeled using a binomial point process, and the antennas are characterized by a sectorized beam pattern. We derive the closed-form expressions for the association probability,the number of accessed users, and the arrival rate of services with certain delay requirements towards different types of NTN. Simulation results are provided to evaluate the influence of various parameters on the association probability, the number of accessed users, and the total arrival rate of services. The number of satellites can be determined to achieve the optimal system utility,balancing the accessed services, offloading effects, and launching costs. This initial investigation lays the groundwork for further theoretical progress in the service analysis and platform deployment of NTN.

关键词： association strategy non-terrestrial networks service analysis stochastic geometry system utility

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

Differential Operator Approach to■quantum Groups and Their Oscillator Representations

引用

Acta Mathematica Sinica,English Series 2024年第5期40卷 1360-1374页

作者： Zhao Bing FAN Ji cheng GENG Shao Long han College of Mathematical Science Harbin Engineering UniversityHarbin 150001P.R.China

For a quasi-split Satake diagram,we define a modified q-Weyl algebra,and show that there is an algebra homomorphism between it and the corresponding■quantum *** other words,we provide a differential operator approach to■quantum ***,the oscillator representations of■quantum groups are *** crystal basis of the irreducible subrepresentations of these oscillator representations are constructed.

关键词： ■quantum group differential operator oscillator representation crystal basis

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

Geochemistry and origins of hydrogen-containing natural gases in deep Songliao Basin,china:Insights from continental scientific drilling

引用

Petroleum Science 2024年第2期21卷 741-751页

作者： Shuang-Biao han Chao-han Xiang Xin Du Lin-Feng Xie Jie Huang cheng-Shan Wang College of Geoscience and Surveying Engineering China University of Mining and TechnologyBeijing100083China State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesBeijing100083China

The different reservoirs in deep Songliao Basin have non-homogeneous lithologies and include multiple layers with a high content of hydrogen *** gas composition and stable isotope characteristics vary significantly,but the origin analysis of different gas types has previously been *** on the geochemical parameters of gas samples from different depths and the analysis of geological settings,this research covers the diverse origins of natural gas in different *** gas components are mainly methane with a small amount of C_(2+),and non-hydrocarbon gases,including nitrogen(N_(2)),hydrogen(H_(2)),carbon dioxide(CO_(2)),and helium(He).At greater depth,the carbon isotope of methane becomes heavier,and the hydrogen isotope points to a lacustrine sedimentary *** increasing depth,the origins of N_(2)and CO_(2)change gradually from a mixture of organic and inorganic to *** origins of hydrogen gas are complex and include organic sources,water radiolysis,water-rock(Fe^(2+)-containing minerals)reactions,and *** shales of Denglouku and Shahezi Formations,as source rocks,provide the premise for generation and occurrence of organic ***,the deep faults and fluid activities in Basement Formation control the generation and migration of mantle-derived *** discovery of a high content of H_(2)in study area not only reveals the organic and inorganic association of natural-gas generation,but also provides a scientific basis for the exploration of deep hydrogen-rich gas.

关键词： Gas compositions Stable isotopes Gas origins Hydrogen gas Songliao Basin

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

Early peripheral perfusion index predicts 28-day outcome in patients with septic shock

引用

World Journal of Emergency Medicine 2024年第5期15卷 372-378页

作者： cheng chi Hao Gong Kai Yang Peng Peng Xiaoxia Zhang Department of Emergency Peking University People's HospitalBeijing 100044China Department of Emergency Intensive Care Unit the First Affi liated Hospital of Xinjiang Medical UniversityUrumqi 830000China

BACKGROUND:To investigate the prognostic value of the peripheral perfusion index(PPI)in patients with septic ***:This prospective cohort study,conducted at the emergency intensive care unit of Peking University People's Hospital,recruited 200 patients with septic shock between January 2023 and August *** patients were divided into survival(n=84)and death(n=116)groups based on 28-day *** evaluations included laboratory tests and clinical scores,with lactate and PPI values assessed upon admission to the emergency room and at 6 h and 12 h after *** factors associated with mortality were analyzed using univariate and multivariate Cox regression *** operator characteristic(ROC)curve was used to assess predictive *** rates were compared,and Kaplan-Meier survival plots were ***:Compared to the survival group,patients in the death group were older and had more severe liver damage and coagulation dysfunction,necessitating higher norepinephrine doses and increased fl uid *** lactate levels and lower PPI levels at 0 h,6 h,and 12 h were observed in the death *** Cox regression identifi ed prolonged prothrombin time(PT),decreased 6-h PPI and 12-h PPI as independent risk factors for *** area under the curves for 6-h PPI and 12-h PPI were 0.802(95%CI 0.742-0.863,Phan in the high PPI groups(6-h PPI:77.52%vs.22.54%;12-h PPI:92.04%vs.13.79%,P<0.001).CONCLUSION:PPI may have value in predicting 28-day mortality in patients with septic shock.

关键词： Peripheral perfusion index Septic shock Prognosis Predictive value

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

Printable,flexible ceramic fiber paper based on electrospinning

引用

Rare Metals 2024年第6期43卷 2739-2746页

作者： Yong-Shuai Xie Yuan cheng Yang Lyu Rui Li Jie-Cai han National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Harbin Institute of TechnologyHarbin 150001China State Key Laboratory of Intelligent Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China

Based on the fact that it is challenging for the polymer flexible circuit substrates to meet the requirements of serving in high-temperature environments,this work proposed the idea of using printable ceramic fiber paper as a high-temperature flexible circuit substrate.A ceramic fiber paper with all ceramic components had been developed via electrospinning,solving the problems of low strength and severe strength drop at high temperatures of traditional ceramic fiber *** tensile strength of the prepared ceramic fiber paper is 2.63 MPa,and the reliable service temperature is 1200℃.Its bulk density is about 1.5 times that of traditional ceramic fiber *** can be printed with patterns by commercial inkjet printers like ordinary printing paper and has excellent *** feasibility of ceramic fiber paper as a flexible circuit substrate was verified by constructing a simple *** the fiber paper is significantly bent,the circuit still forms a complete path,which proves that it has a strong application potential for high-temperature flexible circuit substrate and is expected to promote the development of flexible electronic devices serving at extreme high-temperature environments.

关键词： Ceramic fiber paper High temperature Inkjet printing Flexible electronic

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：