期刊文献+
共找到1,377篇文章
< 1 2 69 >
每页显示 20 50 100
Input Structure Design for Structural Controllability of Complex Networks 被引量:1
1
作者 Lifu Wang Zhaofei Li +2 位作者 Guotao Zhao Ge Guo Zhi Kong 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2023年第7期1571-1581,共11页
This paper addresses the problem of the input design of large-scale complex networks.Two types of network components,redundant inaccessible strongly connected component(RISCC)and intermittent inaccessible strongly con... This paper addresses the problem of the input design of large-scale complex networks.Two types of network components,redundant inaccessible strongly connected component(RISCC)and intermittent inaccessible strongly connected component(IISCC)are defined,and a subnetwork called a driver network is developed.Based on these,an efficient method is proposed to find the minimum number of controlled nodes to achieve structural complete controllability of a network,in the case that each input can act on multiple state nodes.The range of the number of input nodes to achieve minimal control,and the configuration method(the connection between the input nodes and the controlled nodes)are presented.All possible input solutions can be obtained by this method.Moreover,we give an example and some experiments on real-world networks to illustrate the effectiveness of the method. 展开更多
关键词 Complex network input configuration minimum controlled node set structural controllability
下载PDF
Defected Ground Structure Multiple Input-Output Antenna For Wireless Applications
2
作者 Ramya Sridhar Vijayalakshimi Patteeswaran 《Computer Systems Science & Engineering》 SCIE EI 2023年第8期2109-2122,共14页
In this paper,the investigation of a novel compact 2×2,2×1,and 1×1 Ultra-Wide Band(UWB)based Multiple-Input Multiple-Output(MIMO)antenna with Defected Ground Structure(DGS)is employed.The proposed Elect... In this paper,the investigation of a novel compact 2×2,2×1,and 1×1 Ultra-Wide Band(UWB)based Multiple-Input Multiple-Output(MIMO)antenna with Defected Ground Structure(DGS)is employed.The proposed Electromagnetic Radiation Structures(ERS)is composed of multiple radiating elements.These MIMO antennas are designed and analyzed with and without DGS.The feeding is introduced by a microstrip-fed line to significantly moderate the radiating structure’s overall size,which is 60×40×1 mm.The high directivity and divergence characteristics are attained by introducing the microstripfed lines perpendicular to each other.And the projected MIMO antenna structures are compared with others by using parameters like Return Loss(RL),Voltage Standing Wave Ratio(VSWR),Radiation Pattern(RP),radiation efficiency,and directivity.The same MIMO set-up is redesigned with DGS,and the resultant parameters are compared.Finally,the Multiple Input and Multiple Output Radiating Structures with and without DGS are compared for result considerations like RL,VSWR,RP,radiation efficiency,and directivity.This projected antenna displays an omnidirectional RP with moderate gain,which is highly recommended for human healthcare applications.By introducing the defected ground structure in bottom layer the lower cut-off frequencies of 2.3,4.5 and 6.0 GHz are achieved with few biological effects on radio propagation in human body communications.The proposed design covers numerous well-known wireless standards,along with dual-function DGS slots,and it can be easily integrated into Wireless Body Area Networks(WBAN)in medical applications.This WBAN links the autonomous nodes that may be situated either in the clothes,on-body or beneath the skin of a person.This system typically advances the complete human body and the inter-connected nodes through a wireless communication channel. 展开更多
关键词 MIMO-multiple input multiple output defected ground structure WBAN-wireless body area networks ULTRA-WIDEBAND voltage standing wave ratio
下载PDF
Factor input structure,environmental policies,and the export quality upgrade:a perspective of heterogeneity 被引量:3
3
作者 Jiayue Liu Jing Xie 《Chinese Journal of Population,Resources and Environment》 2018年第1期67-76,共10页
In the analysis of how environmental regulation affects the comparative advantage of trade,existing literature ignores industry's inherent heterogeneity, which draws remarkably different conclusions. In view of th... In the analysis of how environmental regulation affects the comparative advantage of trade,existing literature ignores industry's inherent heterogeneity, which draws remarkably different conclusions. In view of this, the paper analyzed the mechanism of environmental regulation on the export quality of different industries from the perspective of factor input structure heterogeneity. Based on the panel data of China's manufacturing industry, the paper used the system generalized method of moments method to examine the heterogeneity influence of environmental regulation on manufacturing export quality. The study found that, first, environmental regulation affected the export quality upgrade of the manufacturing sector through offset effect and compensation effect, and the direction of the impact would mainly depend on the industry's factor input structure. Second, for industries with larger fixed-asset investment(FAI) ratio in the factor input structure, the current environmental regulation policy was not conducive to the export quality upgrading of the industries. However, there was a significant U-shaped dynamic relationship between them. As environmental regulations became stricter, when regulatory stringency went beyond the inflection point, the policy would promote the upgrading of export quality. But for industries with smaller proportion of FAI, environmental regulation exerted a favorable impact on the export quality upgrade, following a J-shaped marginal growth curve.Third, for industries with different factor input structure, their export quality had been effectively upgraded as expected by factors like human capital investment, independent R&D, technology introduction, and foreign direct investment; but raising per capita capital stock and expanding enterprise size did not produce significant direct impact on export quality upgrade. These conclusions remained robust after using different measurement methods and replacing with other variables. Therefore, this paper suggests that governments should take industry heterogeneity into consideration and formulate differentiated hierarchical environmental policies.Besides, they should strengthen the enforcement of the current environmental regulation policies. By doing so, enterprises are forced to improve their technology and product quality so that they can better cope with rising compliance costs, eliminate backward industries, and resolve excess capacity. In this way, the economic structure would be transformed and upgraded from the supply side. 展开更多
关键词 Environmental regulation export quality factor input structure industry heterogeneity
下载PDF
Seismic wave input method for three-dimensional soil-structure dynamic interaction analysis based on the substructure of artificial boundaries 被引量:16
4
作者 Liu Jingbo Tan Hui +2 位作者 Bao Xin Wang Dongyang Li Shutao 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2019年第4期747-758,共12页
The method of inputting the seismic wave determines the accuracy of the simulation of soil-structure dynamic interaction. The wave method is a commonly used approach for seismic wave input, which converts the incident... The method of inputting the seismic wave determines the accuracy of the simulation of soil-structure dynamic interaction. The wave method is a commonly used approach for seismic wave input, which converts the incident wave into equivalent loads on the cutoff boundaries. The wave method has high precision, but the implementation is complicated, especially for three-dimensional models. By deducing another form of equivalent input seismic loads in the fi nite element model, a new seismic wave input method is proposed. In the new method, by imposing the displacements of the free wave fi eld on the nodes of the substructure composed of elements that contain artifi cial boundaries, the equivalent input seismic loads are obtained through dynamic analysis of the substructure. Subsequently, the equivalent input seismic loads are imposed on the artifi cial boundary nodes to complete the seismic wave input and perform seismic analysis of the soil-structure dynamic interaction model. Compared with the wave method, the new method is simplifi ed by avoiding the complex processes of calculating the equivalent input seismic loads. The validity of the new method is verifi ed by the dynamic analysis numerical examples of the homogeneous and layered half space under vertical and oblique incident seismic waves. 展开更多
关键词 soil-structure dynamic interaction SEISMIC WAVE input WAVE method EQUIVALENT input SEISMIC loads SUBstructure of artifi cial boundaries
下载PDF
AN ANALYSIS ON INPUT IMPEDANCE OF A SINGLE MICROSTRIP PATCH IN THE QUASI-OPTICAL CAVITY
5
作者 何宜军 杨铨让 《Journal of Electronics(China)》 1994年第2期150-155,共6页
The electromagnetic field integral equation in the quasi-optical cavity is obtained using the dyadic Green’s function. An expression is derived for the input impedance of a single microstrip patch cavity excited by a... The electromagnetic field integral equation in the quasi-optical cavity is obtained using the dyadic Green’s function. An expression is derived for the input impedance of a single microstrip patch cavity excited by a coaxial probe using moment method. The input impedance of a rectangular microstrip patch is discussed with this method. The result of this paper is similar to that of the microstrip antenna. This paper is of very important value for designing microstrip quasi-optical oscillator. 展开更多
关键词 OSCILLATOR quasi-optical CAVITY input IMPEDANCE MICROSTRIP PATCH MOMENT method
下载PDF
ROBUST STABILIZATING FOR A OLASS OF UNOERTAIN NONLINEAR INTEROONNECTED SYSTEMS USING VARIABLE STRUCTURE CONTROL
6
作者 姜斌 万健如 王先来 《Transactions of Tianjin University》 EI CAS 1999年第1期42-46,共5页
The robust stabilizating control problem for a class of uncertain nonlinear large-scale systems is discussed. Based on the theory of both input/output (I/O) linearization and decentralized variable structure control (... The robust stabilizating control problem for a class of uncertain nonlinear large-scale systems is discussed. Based on the theory of both input/output (I/O) linearization and decentralized variable structure control (VSC),two-level and decentralized variable structure control laws for this kind of systems are presented respectively,which achieve asymptotically stabilization despite the uncertainties and disturbances. At last,sirnulation of the disturbed two-pendulum system is given to illustrate the feasibility of proposed technique. 展开更多
关键词 nonlinear interconnected systems UNCERTAINTY STABILIZATION variable structure control input/output linearization
下载PDF
Decentralized Variable Structure Control of Complex Giant Singular Uncertainty Systems 被引量:1
7
作者 Wen Xiangcai&Liu Yongqing (Department of Automation, South China University of Technology Guangzhou, 510641, P. R. China.) 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 1996年第1期23-34,共12页
This paper, at the first time, considers the problem of decentralized variable structure control of complex giant singular uncertainty systems by using the property of diagonally dominant matrix and Frobenius-Person t... This paper, at the first time, considers the problem of decentralized variable structure control of complex giant singular uncertainty systems by using the property of diagonally dominant matrix and Frobenius-Person theorem. The splendid selection of switching manifold for each subsystem makes the design relatively straightforward and can be easily realized. An illustrate example is given. 展开更多
关键词 Complex giant singular uncertainty systems Multiple input interconnected Decentralized variable structure control Sliding mode Completely controllable.
下载PDF
Crosscumulants Based Approaches for the Structure Identification of Volterra Models
8
作者 Houda Mathlouthi Kamel Abederrahim +1 位作者 Faouzi Msahli Gerard Favier 《International Journal of Automation and computing》 EI 2009年第4期420-430,共11页
In this paper, we address the problem of structure identification of Volterra models. It consists in estimating the model order and the memory length of each kernel. Two methods based on input-output crosscumulants ar... In this paper, we address the problem of structure identification of Volterra models. It consists in estimating the model order and the memory length of each kernel. Two methods based on input-output crosscumulants are developed. The first one uses zero mean independent and identically distributed Caussian input, and the second one concerns a symmetric input sequence. Simulations are performed on six models having different orders and kernel memory lengths to demonstrate the advantages of the proposed methods. 展开更多
关键词 structure identification Volterra model crosscumulants Caussian input symmetric input
下载PDF
New Formula for Evaluating the Number of Unit Cell of a Finite Periodic Structure Considered as Infinite Periodic One
9
作者 Samia Bouali Taoufik Aguili 《Journal of Electromagnetic Analysis and Applications》 2011年第9期343-350,共8页
This paper presents a modeling and an analysis of one-dimensional periodic structure composed of a cascade connection of N cells considered as infinite. The ABCD matrix representations with the Floquet analysis have b... This paper presents a modeling and an analysis of one-dimensional periodic structure composed of a cascade connection of N cells considered as infinite. The ABCD matrix representations with the Floquet analysis have been used to derive the dispersion relation and input impedance of infinite periodic structure. The transmission matrix for the N identical cascaded cells has been successfully used to obtain an efficient and easy-to-use formula giving the necessary number of cells such that they can be considered infinite. As an illustrative example, the formula is applied and verified to finite size TL periodically loaded with obstacles. Scattering parameters and the input impedance of the structure are expressed and plotted. 展开更多
关键词 PERIODIC structure FLOQUET THEOREM Dispersion RELATION Scattering Parameters input IMPEDANCE
下载PDF
A comparative analysis of seismic response of shallow buried underground structure under incident P,SV and Rayleigh waves
10
作者 Xin Bao Jingbo Liu +2 位作者 Hui Tan Shutao Li Fei Wang 《Earthquake Research Advances》 CSCD 2022年第4期72-78,共7页
In this study,A time-domain seismic response analysis method and a calculation model of the underground structure that can realize the input of seismic P,SV and Rayleigh waves are established,based on the viscoelastic... In this study,A time-domain seismic response analysis method and a calculation model of the underground structure that can realize the input of seismic P,SV and Rayleigh waves are established,based on the viscoelastic artificial boundary elements and the boundary substructure method for seismic wave input.After verifying the calculation accuracy,a comparative study on seismic response of a shallow-buried,double-deck,double-span subway station structure under incident P,SV and Rayleigh waves is conducted.The research results show that there are certain differences in the cross-sectional internal force distribution characteristics of underground structures under different types of seismic waves.The research results show that there are certain differences in the internal force distribution characteristics of underground structures under different types of seismic waves.At the bottom of the side wall,the top and bottom of the center pillar of the underground structure,the section bending moments of the underground structure under the incidences of SV wave and Rayleigh wave are relatively close,and are significantly larger than the calculation result under the incidence of P wave.At the center of the side wall and the top floor of the structure,the peak value of the cross-sectional internal force under the incident Rayleigh wave is larger than the calculation result under SV wave.In addition,the floor of the underground structure under Rayleigh waves vibrates in both the horizontal and vertical directions,and the magnification effect in the vertical direction is more significant.Considering that the current seismic research of underground structures mainly considers the effect of body waves such as the shear waves,sufficient attention should be paid to the incidence of Rayleigh waves in the future seismic design of shallow underground structures. 展开更多
关键词 Underground structure Rayleigh wave Artificial boundary Seismic wave input Seismic response
下载PDF
Electromagnetic Modeling of a Planar Structure Integrating a Via-Hole Using the Method FWCIP
11
作者 Sameh Toumi Sahli Fethi Mejri Taoufik Aguili 《Open Journal of Antennas and Propagation》 2016年第2期64-84,共21页
We present in this paper a new formulation of the iterative method FWCIP “Fast Wave Concept Iterative Process” based on the wave concept. It calculates the electromagnetic parameters of a planar structure including ... We present in this paper a new formulation of the iterative method FWCIP “Fast Wave Concept Iterative Process” based on the wave concept. It calculates the electromagnetic parameters of a planar structure including a via-hole. This is modelled by the electromagnetic field that it creates in the structure. The validation of results found by this new formulation is ensured by comparison with those obtained by HFSS “high frequency structural simulator” software from Ansoft. They show that they are in good agreement. 展开更多
关键词 Microstrip Line Iterative Method FWCIP Impedance input Planar structure Via-Hole
下载PDF
The Application of Two-stage Structure Decomposition Technique to the Study of Industrial Carbon Emissions
12
作者 Yanqiu HE 《International Journal of Technology Management》 2015年第8期53-56,共4页
The total carbon emissions control is the ultimate goal of carbon emission reduction, while industrial carbon emissions are the basic units of the total carbon emission. On the basis of existing research results, in t... The total carbon emissions control is the ultimate goal of carbon emission reduction, while industrial carbon emissions are the basic units of the total carbon emission. On the basis of existing research results, in this paper, a two-stage input-output structure decomposition method is creatively proposed for fully combining the input-output method with the structure decomposition technique. In this study, more comprehensive technical progress indicators were chosen in comparison with the previous studies and included the utilization efficiency of all kinds of intermediate inputs such as energy and non-energy products, and finally were positioned at the factors affecting the carbon emissions of different industries. Through analysis, the affecting rate of each factor on industrial carbon emissions was acquired. Thus, a theory basis and data support is provided for the total carbon emissions control of China from the perspective of industrial emissions. 展开更多
关键词 CARBON EMISSIONS Total CARBON EMISSIONS COEFFICIENT input and Output TWO-STAGE structure DECOMPOSITION
下载PDF
Pipeline structure Schnorr-Euchner Sphere Decoding Algorithm
13
作者 Xinyu Mao Jianjun Wu Haige Xiang 《Communications and Network》 2013年第3期108-112,共5页
We propose a pipeline structure for Schnorr-Euchner sphere decoding algorithm in this article. It divides the search tree of the original algorithm into blocks and executes the search from block to block. When one blo... We propose a pipeline structure for Schnorr-Euchner sphere decoding algorithm in this article. It divides the search tree of the original algorithm into blocks and executes the search from block to block. When one block search of a signal is over, the part in the pipeline structure that processes this block search can load another signal and search. Several signals can be processed at the same time in one pipeline. Blocks are arranged to lower the whole complexity in the way that the previously search blocks are the blocks those have more probability to generate the final solution. Simulation experiment results show the average process delay can drop to the range from 48.77% to 60.18% in a 4-by-4 antenna system with 16QAM modulation, or from 30.31% to 61.59% in a 4-by-4 antenna system with 64QAM modulation. 展开更多
关键词 MULTIPLE-input Multiple-Output SYSTEM Schnorr-Euchner SPHERE DECODING PIPELINE structure
下载PDF
基于IO-SDA法的2020~2060年中国行业CO_(2)排放预测与分析 被引量:2
14
作者 王火根 汪钰婷 肖丽香 《中国环境科学》 EI CAS CSCD 北大核心 2024年第3期1743-1755,共13页
采用IO-SDA法测算2017~2020年CO_(2)排放,后结合国内权威预测报告,利用RAS法推导2025~2060年投入产出表和各行业能源消费数据,利用IO-SDA法定量评价各驱动因素在2020~2060年对CO_(2)排放总量和各行业CO_(2)排放量变化的贡献.结果表明:20... 采用IO-SDA法测算2017~2020年CO_(2)排放,后结合国内权威预测报告,利用RAS法推导2025~2060年投入产出表和各行业能源消费数据,利用IO-SDA法定量评价各驱动因素在2020~2060年对CO_(2)排放总量和各行业CO_(2)排放量变化的贡献.结果表明:2020~2060年中国行业CO_(2)排放总量呈现先增后降的趋势,2030年左右达峰,后经历平台期,2035年开始快速减排,2050年后减排速度变慢;CO_(2)排放增长的驱动因素为最终需求规模,最主要的促降因素为碳排放强度;投入产出结构和最终需求结构只在个别时期促进CO_(2)排放增长,总体上对CO_(2)减排有积极作用,但作用有限,且伴随着经济结构趋于稳定,这两者的作用逐渐削弱;CO_(2)排放总量和4项因素的变化幅度在达峰平台期、快速减排期与全面中和期3个阶段由小变大再变小;从行业角度看,电力等公共品生产和供应业、金属产品制造业、交通运输仓储和邮政业、化学工业是CO_(2)减排的主要动力.为有效实现CO_(2)减排目标,政府实施CO_(2)减排政策的过程中,应在继续充分发挥碳排放强度积极效应的同时,更加注重释放重点行业技术创新、最终需求结构优化对CO_(2)减排的积极作用. 展开更多
关键词 碳中和 投入产出 结构分解法 RAS法 中国
下载PDF
基于复杂网络分析的广东省城镇居民碳足迹研究 被引量:1
15
作者 谭蓉娟 单一丹 《生态经济》 北大核心 2024年第7期33-43,共11页
应用投入产出模型和复杂网络分析方法,计算了广东省城镇居民直接碳足迹、间接碳足迹,构建了城镇居民间接碳足迹复杂网络,并对碳足迹重点产业部门进行了结构分解分析。研究结果表明:(1)广东省城镇居民直接碳足迹的主要来源是汽油和液化... 应用投入产出模型和复杂网络分析方法,计算了广东省城镇居民直接碳足迹、间接碳足迹,构建了城镇居民间接碳足迹复杂网络,并对碳足迹重点产业部门进行了结构分解分析。研究结果表明:(1)广东省城镇居民直接碳足迹的主要来源是汽油和液化石油气,间接碳足迹网络的核心产业部门是电力、热力的生产和供应业。(2)广东省城镇居民碳足迹的主要来源为间接碳足迹,对所构建的碳足迹网络进行整体结构和个体特征两方面的分析发现,城镇居民间接碳足迹网络的通达性逐年向好,但各产业部门之间的协同碳关联关系的发挥尚有提升空间。(3)根据产业部门在碳足迹网络中的地位和作用,运用相关指标将其划分为碳核心社区、碳中介社区、碳边缘社区,在对碳核心社区的结构分解分析中发现,碳排放强度效应均为减碳因素,消费水平效应、城镇化水平效应、人口效应为增碳因素,且消费水平效应的增碳贡献率最大。 展开更多
关键词 城镇居民消费 碳足迹 投入产出分析 复杂网络 结构分解分析
下载PDF
需求侧视角下数字经济拉动经济增长的因素分解 被引量:1
16
作者 刘宇 娜尔克斯·努尔旦别克 《兰州财经大学学报》 2024年第1期33-42,共10页
文章从需求侧角度研究数字经济对国民经济的影响,在此基础上运用国家统计局发布的数字经济核心产业分类标准,构建了2017年、2020年数字经济核心产业可比价非竞争型投入产出表,采用“假设抽取”调整的Leonti-ef模型测算了需求拉动作用下... 文章从需求侧角度研究数字经济对国民经济的影响,在此基础上运用国家统计局发布的数字经济核心产业分类标准,构建了2017年、2020年数字经济核心产业可比价非竞争型投入产出表,采用“假设抽取”调整的Leonti-ef模型测算了需求拉动作用下数字经济核心产业的产出效应,进一步地运用结构分解方法对各产业部门的产出增长因素进行分析。结果表明:数字经济核心产业对国民经济有显著的需求拉动效应,且通过后向关联效应对上游产业具有一定的带动作用,其产出量的变化是引起国民经济其他部门产出增长的主要原因。因此,发展数字经济需要在加强数字经济与传统产业融合的同时,特别要重视数字经济核心产业从需求侧“赋能”所引发的产出效应,并充分发挥其在需求侧产出效应的优势。 展开更多
关键词 数字经济核心产业 需求拉动 投入产出 结构分解
下载PDF
基于输入−状态联合估计的漂浮式风机塔架结构载荷反演及状态分析
17
作者 王超 崔明浩 +2 位作者 周楠 陈鹏 程正顺 《中国舰船研究》 CSCD 北大核心 2024年第4期167-175,共9页
[目的]旨在研究波浪作用下漂浮式风机塔架的结构载荷反演方法及动力响应状态。[方法]以半潜型风机为研究对象,通过时域仿真模拟测量数据,并且基于漂浮式风机的频域仿真模型计算塔架的质量归一化模态,将二者作为输入−状态联合估计(joint ... [目的]旨在研究波浪作用下漂浮式风机塔架的结构载荷反演方法及动力响应状态。[方法]以半潜型风机为研究对象,通过时域仿真模拟测量数据,并且基于漂浮式风机的频域仿真模型计算塔架的质量归一化模态,将二者作为输入−状态联合估计(joint input-state estimation,JIS)算法的输入,对漂浮式风机塔架开展结构载荷反演以及实时状态分析。[结果]结果表明:基于JIS算法,以塔架节点的仿真数据作为算法的输入,估计的塔根载荷以及塔架节点响应与仿真结果具有良好的一致性,实现了高精度的反演。[结论]反演结果验证了JIS算法的有效性,可以用于漂浮式风机的实时状态分析,保障漂浮式风机长期安全稳定运行。 展开更多
关键词 漂浮式风机 结构载荷反演 输入−状态联合估计 实时状态分析
下载PDF
一种紧凑型低耦合超宽带MIMO天线设计
18
作者 南敬昌 赵龙友 +2 位作者 高明明 陆筝 苏东蕊 《电波科学学报》 CSCD 北大核心 2024年第4期732-740,共9页
针对目前超宽带多输入多输出(ultra wideband multiple-input multiple-output,UWB-MIMO)天线存在尺寸大、隔离度低等不足,设计了一款紧凑型高隔离度UWB-MIMO天线。天线正面由“花瓶”形辐射贴片与阶梯形微带馈线组合而成,背面是具有切... 针对目前超宽带多输入多输出(ultra wideband multiple-input multiple-output,UWB-MIMO)天线存在尺寸大、隔离度低等不足,设计了一款紧凑型高隔离度UWB-MIMO天线。天线正面由“花瓶”形辐射贴片与阶梯形微带馈线组合而成,背面是具有切角的矩形接地板。通过对矩形辐射贴片对称切角、对接地板刻蚀矩形槽,实现天线的宽带化;通过在介质基板正反两面分别加载“鱼骨”形和改进对称“Y”形去耦枝节,实现天线的高隔离度。仿真与实测结果表明:天线尺寸较小,仅有22 mm×29 mm×0.8 mm,最终工作带宽可达1.5~18 GHz(相对带宽为169%),带内隔离度均高于17 dB,包络相关系数小于0.02。天线辐射性能良好且结构简单紧凑,可以很好地应用于UWB-MIMO无线通信系统中。 展开更多
关键词 阶梯形馈线 多输入多输出(MIMO) 高隔离度 去耦枝节 渐变结构
下载PDF
基于多区域投入产出的黄河流域贸易隐含碳排放时空格局及结构分解
19
作者 吴乐英 赵义义 +1 位作者 苗长虹 杜锦 《生态学报》 CAS CSCD 北大核心 2024年第19期8737-8750,共14页
厘清黄河流域贸易隐含碳排放时空格局及其驱动因素,对于制定公平有效的减排方案,实现区域合作减排的重要目标至关重要。利用多区域投入产出模型深入研究2007—2017年黄河流域9个省区贸易隐含碳排放的构成,以及其在省级和行业层面的转移... 厘清黄河流域贸易隐含碳排放时空格局及其驱动因素,对于制定公平有效的减排方案,实现区域合作减排的重要目标至关重要。利用多区域投入产出模型深入研究2007—2017年黄河流域9个省区贸易隐含碳排放的构成,以及其在省级和行业层面的转移路径;通过结构分解方法,追踪黄河流域贸易隐含碳排放区域内外的影响因素,揭示其区域内外影响因素的异质性。结果表明:黄河流域整体呈净贸易隐含碳转出区域,主要由中间投入的贸易方式进入其他各省的生产需求时导致。该流域的生产供应和整体需求正向中西部和东北地区转移,而对东南沿海省份的供应和需求正逐渐减少。区域外的最终需求和本地的碳排放强度是影响转出贸易隐含碳的主要因素,区域内的最终需求和区域外的碳排放强度是影响转入贸易隐含碳的主要因素。此外,生产结构和最终需求是影响黄河流域贸易隐含碳排放的关键因素,前者对黄河流域贸易隐含碳排放起抑制作用,后者则主要起驱动作用。 展开更多
关键词 黄河流域 多区域投入产出模型 贸易隐含碳排放 结构分解
下载PDF
地下结构地震响应分析的高效混合模拟方法
20
作者 禹海涛 王治坤 《岩土工程学报》 EI CAS CSCD 北大核心 2024年第1期45-53,共9页
数值模拟是地下结构抗震分析的重要手段之一,然而地震动输入及边界效应、模型尺度规模等因素均会影响数值模拟的计算精度和效率,并且存在计算尺度、计算时间、计算精度之间的矛盾,因此如何高效、精确地模拟地下结构与地层相互作用体系... 数值模拟是地下结构抗震分析的重要手段之一,然而地震动输入及边界效应、模型尺度规模等因素均会影响数值模拟的计算精度和效率,并且存在计算尺度、计算时间、计算精度之间的矛盾,因此如何高效、精确地模拟地下结构与地层相互作用体系的地震响应仍是亟待解决的关键问题。基于区域缩减法(DRM)将边界元和有限元相融合的核心思想,旨在建立能够合理模拟地下结构-地层系统地震响应特征的高效混合分析方法。首先将地下结构-地层整体模型划分为近场地层-结构内域子模型和远场地层外域子模型,通过构造重合节点保证内域-外域耦合边界处的位移连续性;其次,基于边界元求解外域自由场或地形影响下的非自由场地震动特征,并采用DRM构造矩阵方程将外域动力响应转化为等效地震荷载,可以在保证地震动合理输入的前提下极大地缩减外域模型尺寸,进而实现对内域中地下结构地震响应的快速参数化分析;最后,设计了两组典型算例以检验该方法的可靠性和高效性。结果表明:对于无地形影响下的双线隧道地震响应模拟,通过与远置边界参考解对比验证了方法的有效性;对于受地形条件影响下的双线隧道地震响应模拟,本方法在保证精度要求的基础上极大缩减了包括地形在内的外域模型范围,相比远置边界法和传统黏弹性法,可使计算模型尺度分别缩减97%和83%,计算时间减少72%和58%。此外,该方法还可推广到斜入射地震动作用下地下结构的动力响应分析。 展开更多
关键词 地下结构 混合方法 区域缩减法 非自由场地震输入
下载PDF
上一页 1 2 69 下一页 到第
使用帮助 返回顶部