期刊文献+
共找到9,964篇文章
< 1 2 250 >
每页显示 20 50 100
Method of Multi-Mode Sensor Data Fusion with an Adaptive Deep Coupling Convolutional Auto-Encoder
1
作者 Xiaoxiong Feng Jianhua Liu 《Journal of Sensor Technology》 2023年第4期69-85,共17页
To address the difficulties in fusing multi-mode sensor data for complex industrial machinery, an adaptive deep coupling convolutional auto-encoder (ADCCAE) fusion method was proposed. First, the multi-mode features e... To address the difficulties in fusing multi-mode sensor data for complex industrial machinery, an adaptive deep coupling convolutional auto-encoder (ADCCAE) fusion method was proposed. First, the multi-mode features extracted synchronously by the CCAE were stacked and fed to the multi-channel convolution layers for fusion. Then, the fused data was passed to all connection layers for compression and fed to the Softmax module for classification. Finally, the coupling loss function coefficients and the network parameters were optimized through an adaptive approach using the gray wolf optimization (GWO) algorithm. Experimental comparisons showed that the proposed ADCCAE fusion model was superior to existing models for multi-mode data fusion. 展开更多
关键词 multi-Mode Data Fusion coupling Convolutional Auto-Encoder Adaptive Optimization Deep Learning
下载PDF
Cellular Automata-based Chloride Ion Diffusion Simulation of Concrete Bridges under Multi-factor Coupling Actions 被引量:2
2
作者 朱劲松 HE Likun 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2012年第1期160-165,共6页
In order to accurately simulate the diffusion of chloride ion in the existing concrete bridge and acquire the precise chloride ion concentration at given time, a cellular automata (CA)-based model is proposed. The pro... In order to accurately simulate the diffusion of chloride ion in the existing concrete bridge and acquire the precise chloride ion concentration at given time, a cellular automata (CA)-based model is proposed. The process of chloride ion diffusion is analyzed by the CA-based method and a nonlinear solution of the Fick's second law is obtained. Considering the impact of various factors such as stress states, temporal and spatial variability of diffusion parameters and water-cement ratio on the process of chloride ion diffusion, the model of chloride ion diffusion under multi-factor coupling actions is presented. A chloride ion penetrating experiment reported in the literature is used to prove the effectiveness and reasonability of the present method, and a T-type beam is taken as an illustrative example to analyze the process of chloride ion diffusion in practical application. The results indicate that CA-based method can simulate the diffusion of chloride ion in the concrete structures with acceptable precision. 展开更多
关键词 氯离子扩散 元胞自动机 多因素耦合 混凝土桥梁 扩散模拟 扩散模型 氯离子浓度 非线性分析
下载PDF
An Evaluation of the Coupling Coordination of Technological Innovation System in China’s Marine Biopharmaceutical Industry
3
作者 FU Xiumei ZHENG Yangming +2 位作者 LIN Chunyu WANG Ping WANG Changyun 《Journal of Ocean University of China》 SCIE CAS CSCD 2023年第1期271-284,共14页
The marine biopharmaceutical industry(MBI)has been considered as an important part of the blue economy.The high-quality development of this industry depends on the high-level coordinated development of technological i... The marine biopharmaceutical industry(MBI)has been considered as an important part of the blue economy.The high-quality development of this industry depends on the high-level coordinated development of technological innovation system(TIS).In the present study,the coupling mechanism of industrial innovation input subsystem and innovation output subsystem was analyzed for the first time.On this basis,the development level and coupling coordination level of TIS in China’s MBI during 2008-2018 were empirically evaluated with the capacity coupling coordination model.Then,the obstacle factors were diagnosed and recognized with the obstacle model.The results showed that the innovation input index fluctuated at a low level in China’s MBI.The innovation output index has basically maintained a growth trend,whereas the quality of development was not high.Although the coupling coordination level of TIS showed a positive change as mild disordered→primary coordinated→well-coordinated,the development type of innovation system has changed from the lagging output of innovation into the lagging input of innovation.Insufficient input of innovation factors remained the main obstacle to the improvement of coordination level.Based on the above analysis,suggestions were put forward from the perspectives of policy and fund guarantees to improve the coupling coordination level in China’s MBI. 展开更多
关键词 marine biopharmaceutical industry technological innovation system subsystem coupling coordinated development obstacle factor
下载PDF
Spatial Coupling Relationship and Driving Mechanism of Population and Economy in Rural Areas in Qinling-Daba Mountains,China
4
作者 XIAO Jie QIAO Jiajun +2 位作者 HAN Dong LIU Yang PAN Tao 《Chinese Geographical Science》 SCIE CSCD 2023年第5期779-795,共17页
Addressing the issue of the healthy and coordinated development of the population and economic factors in rural areas will not only help consolidate and expand the achievements of poverty alleviation,but will also lay... Addressing the issue of the healthy and coordinated development of the population and economic factors in rural areas will not only help consolidate and expand the achievements of poverty alleviation,but will also lay a foundation for comprehensive rural revitalization.In this paper,the spatial coupling relationship between the population and economic factors in rural areas in the QinlingDaba Mountains,China,is explored to provide a reference for rural revitalization and regional sustainable development in poverty areas.Sixty-eight county units in rural areas in the Qinling-Daba Mountains,as well as the population and economic factors in rural areas,are used to study the spatial coupling relationship between population and economy,as well as the driving mechanism,in rural areas in the Qinling-Daba Mountains from 2010 to 2020.The results show that a population contraction phenomenon occurred in the rural areas in the Qinling-Daba Mountains,and the spatial agglomeration trends of the population and economic factors were consistent.The agglomeration was mainly located in the suburban areas of the municipal area,and the agglomeration degree was significantly higher in these areas than in other areas.In terms of the spatial distribution,the economic development level of the rural areas in the northeastern part of the Qinling-Daba Mountains was generally higher than that in the central and western parts,and the unbalanced trends of the population and economic spatial differentiation in the eastern and western regions were significant.The spatial coupling relationship between the population and economy changed from coordinated development to economic advancement.This was mainly due to the mutual restriction and joint actions of the industrial structure,capital situation,natural environment,policies,and institutional regulations,among which the industrial structure and capital status had significant effects. 展开更多
关键词 rural poverty population distribution economic development pattern spatial coupling influencing factors rural revitalization Qinling-Daba Mountains China
下载PDF
Factors Associated with Unmet Need for Family Planning among Couples Living in Urban and Rural Areas of Guinea in 2019
5
作者 Soumah Aboubacar Fode Momo Conte Ibrahima +2 位作者 Bah Oumou Hawa Daniel William Athanass Leno Sy Telly 《Open Journal of Obstetrics and Gynecology》 2023年第6期1081-1093,共13页
Introduction: Unmet need for family planning (UNFP) is defined as women with unmet needs who want to stop or delay childbearing but are not using any method of contraception. The objective of this study was to analyze... Introduction: Unmet need for family planning (UNFP) is defined as women with unmet needs who want to stop or delay childbearing but are not using any method of contraception. The objective of this study was to analyze the factors associated with unmet needs for family planning among couples living in rural and urban areas of Guinea in 2019. Methodology: This was a prospective, analytical cross-sectional, multicenter study of a six-month period from August 1, 2018 to January 31, 2019, focusing on couples with unmet needs for family planning. Result: Among 189 couples interviewed, 567 had UNFP (33.3%), the reasons for not using modern contraceptive methods were desire for pregnancy (AOR = 2.74, 95% CI: 1.74, 4.31), husband’s refusal (AOR = 0.23, 95% CI: 0.06, 0.81), spousal attitude (AOR = 0.20, 95% CI: 0.130, 30), birth spacing (AOR = 2.10% to 95%: 1.16, 3.82), difficulty with a new pregnancy (AOR = 0.17, 95% CI: 0.04, 0.74), and spousal attitude (AOR = 0.20, 95% CI: 0.14, 0.30). Conclusion: The involvement of spouses, especially in rural communities, would help achieve family planning objectives and reduce unmet needs for family planning. 展开更多
关键词 Associated factors Unmet Need Family Planning couplE RURAL URBAN GUINEA 2019
下载PDF
Multi-component Dirac equation hierarchy and its multi-component integrable couplings system 被引量:8
6
作者 夏铁成 尤福财 《Chinese Physics B》 SCIE EI CAS CSCD 2007年第3期605-610,共6页
关键词 圈代数 多分量可积耦合系统 多分量迪拉克方程谱系 零曲率方程
下载PDF
A generalized multi-field coupling approach and its application to stability and deformation control of a high slope 被引量:5
7
作者 Chuangbing Zhou Yifeng Chen +1 位作者 Qinghui Jiang Wenbo Lu 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE 2011年第3期193-206,共14页
Human activities,such as blasting excavation,bolting,grouting and impounding of reservoirs,will lead to disturbances to rock masses and variations in their structural features and material properties.These engineering... Human activities,such as blasting excavation,bolting,grouting and impounding of reservoirs,will lead to disturbances to rock masses and variations in their structural features and material properties.These engineering disturbances are important factors that would alter the natural evolutionary processes or change the multi-field interactions in the rock masses from their initial equilibrium states.The concept of generalized multi-field couplings was proposed by placing particular emphasis on the role of engineering disturbances in traditional multi-field couplings in rock masses.A mathematical model was then developed,in which the effects of engineering disturbances on the coupling-processes were described with changes in boundary conditions and evolutions in thermo-hydro-mechanical(THM) properties of the rocks.A parameter,d,which is similar to damage variables but has a broader physical meaning,was conceptually introduced to represent the degree of engineering disturbances and the couplings among the material properties.The effects of blasting excavation,bolting and grouting in rock engineering were illustrated with various field observations or theoretical results,on which the degree of disturbances and the variations in elastic moduli and permeabilities were particularly focused.The influences of excavation and groundwater drainage on the seepage flow and stability of the slopes were demonstrated with numerical simulations.The proposed approach was further employed to investigate the coupled hydro-mechanical responses of a high rock slope to excavation,bolting and impounding of the reservoir in the dam left abutment of Jinping I hydropower station.The impacts of engineering disturbances on the deformation and stability of the slope during construction and operation were demonstrated. 展开更多
关键词 高边坡开挖 多场耦合 变形控制 稳定性 广义 锦屏一级水电站 岩体工程 应用
下载PDF
COMSOL Multiphysics在锂离子电池中的应用
8
作者 李校磊 高健 +1 位作者 周伟东 李泓 《储能科学与技术》 CAS CSCD 北大核心 2024年第2期546-567,共22页
作为一种具有前景的能量存储系统,锂离子电池需要进一步提高能量密度、功率密度、可靠性和循环稳定性,以满足不断增长的大型能源存储、电动汽车和便携式电子设备需求。当前对锂离子电池的实验研究仍然面临多个挑战,这些挑战包括电解液... 作为一种具有前景的能量存储系统,锂离子电池需要进一步提高能量密度、功率密度、可靠性和循环稳定性,以满足不断增长的大型能源存储、电动汽车和便携式电子设备需求。当前对锂离子电池的实验研究仍然面临多个挑战,这些挑战包括电解液的导电性和安全性、高能量负极的沉积-剥离机制的优化、高能量正极的循环电压和容量维持、高电流条件下的界面极化和容量释放,以及在极端电流-温度-针刺条件下的热失控管理等问题。这些问题涉及到电-化-力-热等多个场的耦合作用,需要进行协同优化处理。COMSOL Multiphysics提供了一种可行的工具,通过求解多物理场耦合的连续方程,能够同时考虑载流子浓度、电流密度、电-化学势、温度、应力/应变和几何形态等综合信息的演化。本文概述了该工具在锂离子电池的电解液、负极和正极设计等方面的研究,并聚焦于多场耦合对电池性能的综合影响、多场耦合模拟方法以及理论模拟与实验表征的结合。最后,本文对理论与实验联合研究中的多场和多尺度问题进行了展望。 展开更多
关键词 COMSOL multiphysics 锂离子电池 多场耦合 模拟计算
下载PDF
Analysis of high-frequency local coupling instability induced by multi- transmitting formula - P-SV wave simulation in a 2D waveguide 被引量:6
9
作者 Xie Zhinan Zhang Xubin 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2017年第1期1-10,共10页
Local coupling instability will occur when the numerical scheme of absorbing boundary condition and that of the field wave equation allow energies to spontaneously enter into the computational domain.That is, the two ... Local coupling instability will occur when the numerical scheme of absorbing boundary condition and that of the field wave equation allow energies to spontaneously enter into the computational domain.That is, the two schemes support common wave solutions with group velocity pointed into the computation domain.The key to eliminate local coupling instability is to avoid such wave solutions.For lumped-mass finite element simulation of P-SV wave motion in a 2D waveguide, an approach for stable implementation of high order multi-transmitting formula is provided.With a uniform rectangular mesh, it is proven and validated that high-frequency local coupling instability can be eliminated by setting the ratio of the element size equal to or greater than 2^(1/2) times the ratio of the P wave velocity to the S wave velocity.These results can be valuable for dealing instability problems induced by other absorbing boundary conditions. 展开更多
关键词 多次透射公式 P-SV波 有限元模拟 耦合失稳 波导 二维 高频 吸收边界条件
下载PDF
Dynamic Response Impact of Vehicle Braking on Simply Supported Beam Bridges with Corrugated Steel Webs Based on Vehicle-Bridge Coupled Vibration Analysis
10
作者 Yan Wang Siwen Li Na Wei 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第6期3467-3493,共27页
A novel approach for analyzing coupled vibrations between vehicles and bridges is presented,taking into account spatiotemporal effects and mechanical phenomena resulting fromvehicle braking.Efficient modeling and solu... A novel approach for analyzing coupled vibrations between vehicles and bridges is presented,taking into account spatiotemporal effects and mechanical phenomena resulting fromvehicle braking.Efficient modeling and solution of bridge vibrations induced by vehicle deceleration are realized using this method.The method’s validity and reliability are substantiated through numerical examples.A simply supported beam bridge with a corrugated steel web is taken as an example and the effects of parameters such as the initial vehicle speed,braking acceleration,braking location,and road surface roughness on the mid-span displacement and impact factor of the bridge are analyzed.The results show that vehicle braking significantly amplifies mid-span displacement and impact factor responses in comparison to uniform vehicular motion across the bridge.Notably,the influence of wheelto-bridge friction forces is of particular significance and cannot be overlooked.When the vehicle initiates braking near the middle of the span,both the mid-span displacement and impact factor of the bridge exhibit substantial increases,further escalating with higher braking acceleration.Under favorable road surface conditions,the midspan displacement and the impact factor during vehicle braking may exceed the design values stipulated by codes.It is important to note that road surface roughness exerts a more pronounced effect on the impact factor of the bridge in comparison to the effects of vehicle braking. 展开更多
关键词 Corrugated steel web girder bridges simply supported beam bridges vehicle-bridge coupled vibration BRAKING impact factor
下载PDF
Numerical analysis of stability for mined-out area in multi-field coupling 被引量:5
11
作者 罗周全 谢承煜 +3 位作者 周吉明 贾楠 刘晓明 徐海 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第2期669-675,共7页
There were differences between real boundary and blast hole controlling boundary of irregular mined-out area in underground metal mines. There were errors in numerical analysis of stability for goaf, if it was analyze... There were differences between real boundary and blast hole controlling boundary of irregular mined-out area in underground metal mines. There were errors in numerical analysis of stability for goaf, if it was analyzed as regular 3D mined-out area and the influence of coupling stress-seepage-disturbance was not considered adequately. Taking a lead zinc mine as the background, the model was built by the coupling of Surpac and Midas-Gts based on the goaf model precisely measured by CMS.According to seepage stress fundamental equations based on the equivalent continuum mechanical and the theory about equivalent load of dynamic disturbance in deep-hole blasting, the stability of mined-out area under multi-field coupling of stress-seepage-dynamic disturbance was numerically analyzed. The results show that it is more consistent between the numerical analysis model based on the real model of irregular 3D shape goaf and the real situation, which could faithfully reappear the change rule of stress–strain about the surrounding rock under synthetic action of blasting dynamic loading and the seepage pressure. The mined-out area multi-field coupling formed by blasting excavation is stable. Based on combination of the advantages of the CMS,Surpac and Midas-Gts, and fully consideration of the effects of multi-field coupling, the accurate and effective way could be provided for numerical analysis of stability for mined-out area. 展开更多
关键词 数值分析模型 多场耦合 采空区 稳定性 地下金属矿山 耦合应力 渗透压力 等效负载
下载PDF
Generalized Multi-component TC Hierarchy and Its Multi-component Integrable Coupling System 被引量:1
12
作者 XIA Tie-Cheng YOU Fu-Cai 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第5X期793-798,共6页
A new 3M-dimensional Lie algebra X is constructed firstly. Then, the corresponding loop algebra X is produced, whose commutation operation defined by us is as simple and straightforward as that in the loop algebra A1.... A new 3M-dimensional Lie algebra X is constructed firstly. Then, the corresponding loop algebra X is produced, whose commutation operation defined by us is as simple and straightforward as that in the loop algebra A1.It follows that a generalscheme for generating multi-component integrable hierarchy is proposed. By taking advantage of X, a new isospectral problem is established, and then well-known multi-component TC hierarchy is obtained. Finally,an expanding loop algebra FM of the loop algebra X is presented. Based on the FM, the multi-component integrable coupling system of the generalized multi-component TC hierarchy has been worked out. The method in this paper can be applied to other nonlinear evolution equations hierarchies. It is easy to find that we can construct any finite-dimensional Lie algebra by this approach. 展开更多
关键词 LIE代数 可积分耦合函数 环代数 TC层次
下载PDF
Measurements of electron-phonon coupling factor and interfacial thermal resistance of metallic nano-films using a transient thermoreflectance technique 被引量:3
13
作者 王海东 马维刚 +2 位作者 过增元 张兴 王玮 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第4期209-216,共8页
Using a transient thermoreflectance (TTR) technique,several Au films with different thicknesses on glass and SiC substrates are measured for thermal characterization of metallic nano-films,including the electron-phono... Using a transient thermoreflectance (TTR) technique,several Au films with different thicknesses on glass and SiC substrates are measured for thermal characterization of metallic nano-films,including the electron-phonon coupling factor G,interfacial thermal resistance R,and thermal conductivity K s of the substrate. The rear heating-front detecting (RF) method is used to ensure the femtosecond temporal resolution. An intense laser beam is focused on the rear surface to heat the film,and another weak laser beam is focused on the very spot of the front surface to detect the change in the electron temperature. By varying the optical path delay between the two beams,a complete electron temperature profile can be scanned. Different from the normally used single-layer model,the double-layer model involving interfacial thermal resistance is studied here. The electron temperature cooling profile can be affected by the electron energy transfer into the substrate or the electron-phonon interactions in the metallic films. For multiple-target optimization,the genetic algorithm (GA) is used to obtain both G and R. The experimental result gives a deep understanding of the mechanism of ultra-fast heat transfer in metals. 展开更多
关键词 电声子相互作用 电子温度 纳米薄膜 金属薄膜 测量技术 热电阻 耦合系数 激光束聚焦
下载PDF
Coupling effects of influence factors on probability of corrosion initiation time of reinforced concrete 被引量:6
14
作者 张小刚 赵衍刚 +1 位作者 邢锋 卢朝辉 《Journal of Central South University》 SCIE EI CAS 2011年第1期223-229,共7页
The coupling model of major influence factors such as environmental relative humidity,load-induced crack and stress state affecting the chloride diffusion process in concrete is discussed.The probability distributions... The coupling model of major influence factors such as environmental relative humidity,load-induced crack and stress state affecting the chloride diffusion process in concrete is discussed.The probability distributions of the critical chloride concentration CC,the chloride diffusion coefficient D,and the surface chloride concentration Cs were determined based on the collected natural exposure data.And the estimation of probability of corrosion initiation considering the coupling effects of influence factors is presented.It is found that the relative humidity and curing time are the most effective factors affecting the probability of corrosion initiation before and after 10 years of exposure time.At the same exposure time,the influence of load-induced crack and stress state on the probability of corrosion initiation is obvious,in which the effect of crack is the most one. 展开更多
关键词 钢筋混凝土腐蚀 影响因素 概率分布 起始时间 耦合作用 环境相对湿度 氯离子浓度 氯离子扩散系数
下载PDF
Transport properties in a multi-terminal regular polygonal quantum ring with Rashba spin-orbit coupling 被引量:1
15
作者 唐翰昭 翟利学 刘建军 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第12期66-73,共8页
Transport properties in a multi-terminal regular polygonal quantum ring with Rashba spin-orbit coupling(SOC) are investigated analytically using quantum networks and the transport matrix method.The results show that c... Transport properties in a multi-terminal regular polygonal quantum ring with Rashba spin-orbit coupling(SOC) are investigated analytically using quantum networks and the transport matrix method.The results show that conductances remain at exactly the same values when the output leads are located at axisymmetric positions.However,for the nonaxisymmetrical case,there is a phase difference between the upper and lower arm,which leads to zero conductances appearing periodically.An isotropy of the conductance is destroyed by the Rashba SOC effect in the axisymmetric case. In addition,the position of zero conductance is regulated with the strength of the Rashba SOC. 展开更多
关键词 自旋轨道耦合 传输性能 正多边形 多终端 子环 运输 非轴对称 SOC
下载PDF
MULTI-FIELD COUPLING BEHAVIOR OF SIMPLY-SUPPORTED CONDUCTIVE PLATE UNDER THE CONDITION OF A TRANSVERSE STRONG IMPULSIVE MAGNETIC FIELD 被引量:3
16
作者 Zhu Linli Zhang Jianping Zheng Xiaojing 《Acta Mechanica Solida Sinica》 SCIE EI 2006年第3期203-211,共9页
以便学习在一个外部地侧面的强壮的冲动的磁场的条件下面联合 支持thesimply 的传导性的矩形的薄板的机械行为的多地,那是在在旋涡水流和磁场之间的相互作用生产的磁性的体积力量的效果的薄盘子的动态弄弯现象,一个女性的分析节目被... 以便学习在一个外部地侧面的强壮的冲动的磁场的条件下面联合 支持thesimply 的传导性的矩形的薄板的机械行为的多地,那是在在旋涡水流和磁场之间的相互作用生产的磁性的体积力量的效果的薄盘子的动态弄弯现象,一个女性的分析节目被开发描绘磁电的弄弯和盘子的不稳定性的现象。为三个不同起始的颤动模式的磁场的批评价值被获得,与在应用磁场的批评的值B_( 0cr )上在板和长度宽度比率 a/b 以及推动参数τ 的长度厚度比率 a/h 的效果上做的详细讨论。 展开更多
关键词 多场耦合 传导薄板 冲击磁场 涡流 动态压曲 磁场力
下载PDF
Coupling and Coordination Characteristics and Influencing Factors of the Livable Environment System for the Elderly in China
17
作者 CHEN Xiaohong ZHANG Mingxuan +3 位作者 WANG Ying XU Xiaoqing LIU Shuang MA Lingyu 《Chinese Geographical Science》 SCIE CSCD 2022年第6期1052-1068,共17页
The construction of a livable environment for the elderly is an important measure to address the challenges of aging and improve their livelihood and well-being.Based on China’s national conditions and combined with ... The construction of a livable environment for the elderly is an important measure to address the challenges of aging and improve their livelihood and well-being.Based on China’s national conditions and combined with the actual development needs of the cities,it is of great significance to explore the coupling and coordination characteristics and influencing factors within the livable environment system for the elderly for the coordination and stable development.This article was based on the three subsystems of’living service environment,socioeconomic environment and ecological livable environment’,following the research framework of’process-pattern-trend-impact’,constructs an evaluation index system for the livable environment for the elderly.Entropy weight-TOPSIS evaluation model,coupling coordination degree model,center of gravity and standard deviation ellipse model and the geographic detector model were used starting from the evolution of coupling coordination types to study the spatial and temporal pattern and dynamic trend characteristics and influencing factors of internal coupling coordination types in the livable environment system for the elderly from2010 to 2019.The results showed that:1)The coordinated development of life service environment system and ecological livable environment system(LE)and socioeconomic environment system and ecological livable environment system(SE)in the livable environment for the elderly decreased from the intermediate coordination level coordination areas to the low-level quality improvement and optimization areas:coordinated transition type.The overall development level of life service environment system and socioeconomic environment system(LS)was low,and it was always at a low level.2)The coupling degree of livable environment system for the elderly was high,the coupling coordination type shown a gradually decreasing layer structure with Zhejiang,Beijing and Guangdong high-level leading demonstration areas as the axis belt.3)The coupling coordination center of the elderly livable environment system was located in Henan,and the standard deviation ellipse was distributed in the northeast-southwest direction.The development center and the ellipse of the high-level leading demonstration areas and the intermediate coordination level areas were concentrated in the central and eastern regions,while the low-level coordination areas for improving quality and efficiency are mainly located in the western region.4)Urban development,green facilities,infrastructure,government macroscopic regulation and control,economic stimulus,and housing construction were all important factors affecting the coordinated development of the livable environment system for the elderly,exerting a varying degree of effect on the level of coordinated development of various types of systems. 展开更多
关键词 livable environment system the elderly coupling coordination degree spatial and temporal pattern dynamic trend influencing factors China
下载PDF
Carbon,nitrogen and phosphorus coupling relationships and their influencing factors in the critical zone of Dongting Lake wetlands,China
18
作者 Yan-hao Wu Nian-qing Zhou +2 位作者 Zi-jun Wu Shuai-shuai Lu Yi Cai 《Journal of Groundwater Science and Engineering》 2022年第3期250-266,共17页
Wetland is a transition zone between terrestrial and aquatic ecosystems,and is the source and sink of various biogenic elements in the earth’s epipelagic zone.In order to investigate the driving force and coupling me... Wetland is a transition zone between terrestrial and aquatic ecosystems,and is the source and sink of various biogenic elements in the earth’s epipelagic zone.In order to investigate the driving force and coupling mechanism of carbon(C),nitrogen(N)and phosphorus(P)migration in the critical zone of lake wetland,this paper studies the natural wetland of Dongting Lake area,through measuring and analysing the C,N and P contents in the wetland soil and groundwater.Methods of Pearson correlation,non-linear regression and machine learning were employed to analyse the influencing factors,and to explore the coupling patterns of the C,N and P in both soils and groundwater,with data derived from soil and water samples collected from the wetland critical zone.The results show that the mean values of organic carbon(TOC),total nitrogen(TN)and total phosphorus(TP)in groundwater are 1.59 mg/L,4.19 mg/L and 0.5 mg/L,respectively,while the mean values of C,N and P in the soils are 18.05 g/kg,0.86 g/kg and 0.52 g/kg.The results also show that the TOC,TN and TP in the groundwater are driven by a variety of environmental factors.However,the concentrations of C,N and P in the soils are mainly related to vegetation abundance and species which influence each other.In addition,the fitted curves of wetland soil C-N and C-P appear to follow the power function and S-shaped curve,respectively.In order to establish a multivariate regression model,the soil N and P contents were used as the input parameters and the soil C content used as the output one.By comparing the prediction effects of machine learning and nonlinear regression modelling,the results show that coupled relationship equation for the C,N and P contents is highly reliable.Future modelling of the coupled soil and groundwater elemental cycles needs to consider the complexity of hydrogeological conditions and to explore the quantitative relationships among the influencing factors and chemical constituents. 展开更多
关键词 Dongting Lake Wetland critical zone CARBON Nitrogen and phosphorus Driving factors coupling mechanisms
下载PDF
Research on novel multi-layer and multi-polarized slot-coupling planar antenna array
19
作者 ZhangHou Wu Wenzhou Wang Jian 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2009年第2期297-303,共7页
A novel multi-layer planar antenna array to achieve multi-polarized radiation is developed. U-shaped coupling slots are embedded in the ground plane to extend the bandwidth. The phase relation between adjacent element... A novel multi-layer planar antenna array to achieve multi-polarized radiation is developed. U-shaped coupling slots are embedded in the ground plane to extend the bandwidth. The phase relation between adjacent elements in the radiation field is analyzed when adjacent elements are fed in opposite phase. Return loss and radiation pattern are measured for a 16-element antenna array at 12.5 GHz. The radiation pattern shows a good agreement with the calculated one in the shape of the main beam. The return-loss of the proposed antenna array is less than –20 dB in the 12.5 GHz frequency band (12.25-12.75 GHz). Because of two feed ports the antenna can transmit arbitrary elliptic polarized waves if the two feed ports have different amplitude and phase. The main factors such as element spacing, substrate medium and manufacturing imperfection are analyzed and the corresponding conclusions are presented. 展开更多
关键词 天线阵列 多极化 平面 插槽 耦合 椭圆极化波 辐射场 测量模式
下载PDF
Multi-component Levi Hierarchy and Its Multi-component Integrable Coupling System
20
作者 XIA Tie-Cheng YOU Fu-Cai ZHAO Wen-Ying 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第6X期990-996,共7页
A simple 3M-dimensional loop algebra X is produced, whose commutation operation defined by us is as simple and straightforward as that in the loop algebra A1. It follows that a general scheme for generating multicompo... A simple 3M-dimensional loop algebra X is produced, whose commutation operation defined by us is as simple and straightforward as that in the loop algebra A1. It follows that a general scheme for generating multicomponent integrable hierarchy is proposed. By taking advantage of X, a new isospectral problem is established, and then by making use of the Tu scheme the well-known multi-component Levi hierarchy is obtained. Finally, an expanding loop algebra FM of the loop algebra X is presented, based on the FM, the multi-component integrable coupling system of the multi-component Levi hierarchy is worked out. The method in this paper can be applied to other nonlinear evolution equation hierarchies. 展开更多
关键词 多分量Levi层 多分量可积偶合系统 环代数 环论
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部