期刊文献+
共找到4,657篇文章
< 1 2 233 >
每页显示 20 50 100
Analysis and Comparison of Slope-cutting Widening Schemes in Highway Reconstruction and Expansion Project Based on MIDAS Software
1
作者 Zhiqiang Qiu Yun Shi Lei Jiang 《Journal of Architectural Research and Development》 2024年第2期75-83,共9页
In this paper,the geological condition of the right-side slope of the K114+694–K115+162 section of Yong-tai-wen Expressway is investigated and analyzed with the results showing that the strength of rock mass is the m... In this paper,the geological condition of the right-side slope of the K114+694–K115+162 section of Yong-tai-wen Expressway is investigated and analyzed with the results showing that the strength of rock mass is the main contributor to the stability of the slope.Then,two widening schemes are proposed,which are the steep slope with strong support and the gentle slope with general support schemes.The static/slope module of MIDAS GTS finite element analysis software and the strength reduction method were used to compare the two schemes.The results show that the steep slope with a strong support scheme has obvious advantages in land requisition,environmental protection,and safety and is more suitable for reconstructing and expanding the highway slope. 展开更多
关键词 Highway reconstruction and expansion Slope excavation MIDAS GTS Scheme selection
下载PDF
Comparison, Selection and Progeny Test of Natural Populations of White Birch (Betula platyphylla Suk.) in Northern China
2
作者 Shibo LAN 《Agricultural Biotechnology》 CAS 2019年第4期113-118,共6页
[Objectives]This study was conducted to rationally and effectively use natural genetic resources of white birch(Betula platyphylla Suk.),and improve the scientific and technological content of improved varieties.[Meth... [Objectives]This study was conducted to rationally and effectively use natural genetic resources of white birch(Betula platyphylla Suk.),and improve the scientific and technological content of improved varieties.[Methods]With the progeny of the white birch populations naturally distributed in northern China as objects,based on genetic effect analysis and comprehensive evaluation,the genetic variation,heritability and genetic gain of the growth characters in the progeny forest were systematically analyzed,by which populations or individuals with good growth vigor and strong stress resistance and adaptability were finally selected.[Results]There were extremely significant differences in the growth characters between the natural populations of white birch in northern China.The variation was the smallest in tree height,followed by crown width,and largest in DBH,and the average coefficients of variation were 20.56%,32.25%and 33.00%,respectively.The differences in characters between progeny of the same population were also extremely significant.The growth characters of white birch were more controlled by genes,and the genetic gains were larger.The heritability of tree height,DBH and crown width was 0.971,0.816 and 0.576,respectively,and the genetic gains were 15.97%,21.54%and 13.87%,respectively.[Conclusions]With the growth characters as the main evaluation indexes,taking various influencing factors into account,the Shanxi[SX]population,Hebei[HB]population and Liaoning[LN]population were selected to be excellent populations,and LN305,SX516 and HB403 were excellent individuals,which are advised to be widely used in multi-generation genetic improvement breeding. 展开更多
关键词 BETULA platyphylla Suk. Natural population comparison and selection PROGENY test GENETIC effect GENETIC gain
下载PDF
Quantitative comparison screening of seismological indexes and research on the integrated prediction method in North China
3
作者 周翠英 朱元清 +3 位作者 王红卫 梁凯莉 李平 郭爱香 《Acta Seismologica Sinica(English Edition)》 CSCD 1999年第2期232-237,共6页
关键词 comparison screening method quantitative selecting SEISMOLOGY parameters INTEGRATED Prediction
下载PDF
Theoretical Basis for Multiple Criteria Analysis of Variants and Selection of the Most Effective Technological Scheme for Hard Rock Surface Mining
4
作者 Antipas T. S. Massawe Mussa Daniel 《Engineering(科研)》 2011年第1期83-89,共7页
The technological scheme of a hard rock surface mine is a multiple level production system of interdependently func-tioning elements. Selection of the optimum combination of its elements constitutes a complex multiple... The technological scheme of a hard rock surface mine is a multiple level production system of interdependently func-tioning elements. Selection of the optimum combination of its elements constitutes a complex multiple variant and criteria problem of decision making. In this paper describes the theoretical part of the method proposed for the quantitative analysis and selection of the most competent technological schemes, based on the mathematical formulations of the selection criteria of the element of each level as functions of the alternative variants of the elements of the level and its adjacent levels. It is realized in accordance to standard procedures of decision making in the formation of the economical mathematical model of the cumulative influence of levels and elements on the effectiveness of all alternative variants in their analysis and generation of a small subset of the most competent variants, which are subjected to further analysis using the criterion of reliability in the generation of the optimum technological scheme. The scientific challenge inherent in its realization constitutes a PhD research opportunity for those interested in the problems of optimization in hard rock surface mines. 展开更多
关键词 Level Alternative VARIANTS TECHNOLOGICAL schemes selection COMPETENT VARIANTS
下载PDF
Establishment of Knowledge Base Management System and the Type Selection of Mechanism for Mechanism Kinematic Scheme
5
作者 叶志刚 邹慧君 +4 位作者 郭为忠 胡松 田永利 王生泽 唐林 《Journal of Donghua University(English Edition)》 EI CAS 2003年第4期145-149,共5页
Firstly data standardization technology and combined classification method have been applied to carry out classification of kinematic behaviors and mechanisms in the mapping field between the kinematic behavior level ... Firstly data standardization technology and combined classification method have been applied to carry out classification of kinematic behaviors and mechanisms in the mapping field between the kinematic behavior level and the mechanism level of conceptual design.The principle of computer coding and storing have been built to give a fast and broad selection of mechanisms that meets the requirements of basic motion characters.Then on the basis of mentioned above,the heuristic matching propagation principle (HMPP) of kinematic behaviors and its true table serves as a guide to perform mechanism types selection.Finally an application is given to indicate its practicability and effectiveness. 展开更多
关键词 知识基础管理系统 自动控制系统 类型选择机械 数据标准化技术 联合分级方法 运动行为 启发式匹配传播理论 计算机译码
下载PDF
Comparison of Parallel Kinematic Machines with Three Translational Degrees of Freedom and Linear Actuation 被引量:7
6
作者 PRAUSE Isabel CHARAF EDDINE Sami CORVES Burkhard 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2015年第4期841-850,共10页
The development of new robot structures, in particular of parallel kinematic machines(PKM), is widely systematized by different structure synthesis methods. Recent research increasingly focuses on PKM with less than... The development of new robot structures, in particular of parallel kinematic machines(PKM), is widely systematized by different structure synthesis methods. Recent research increasingly focuses on PKM with less than six degrees of freedom(DOF). However, an overall comparison and evaluation of these structures is missing. In order to compare symmetrical PKM with three translational DOF, different evaluation criteria are used. Workspace, maximum actuation forces and velocities, power, actuator stiffness, accuracy and transmission behavior are taken into account to investigate strengths and weaknesses of the PKMs. A selection scheme based on possible configurations of translational PKM including different frame configurations is presented. Moreover, an optimization method based on a genetic algorithm is described to determine the geometric parameters of the selected PKM for an exemplary load case and a prescribed workspace. The values of the mentioned criteria are determined for all considered PKM with respect to certain boundary conditions. The distribution and spreading of these values within the prescribed workspace is presented by using box plots for each criterion. Thereby, the performance characteristics of the different structures can be compared directly. The results show that there is no "best" PKM. Further inquiries such as dynamic or stiffness analysis are necessary to extend the comparison and to finally select a PKM. 展开更多
关键词 parallel kinematic machines comparison BENCHMARK selection scheme
下载PDF
Performance Comparison of Two Efficient Genomic Selection Methods(gsbay & MixP ) Applied in Aquacultural Organisms
7
作者 SU Hailin LI Hengde +2 位作者 WANG Shi WANG Yangfan BAO Zhenmin 《Journal of Ocean University of China》 SCIE CAS CSCD 2017年第1期137-144,共8页
Genomic selection is more and more popular in animal and plant breeding industries all around the world, as it can be applied early in life without impacting selection candidates. The objective of this study was to br... Genomic selection is more and more popular in animal and plant breeding industries all around the world, as it can be applied early in life without impacting selection candidates. The objective of this study was to bring the advantages of genomic selection to scallop breeding. Two different genomic selection tools Mix P and gsbay were applied on genomic evaluation of simulated data and Zhikong scallop(Chlamys farreri) field data. The data were compared with genomic best linear unbiased prediction(GBLUP) method which has been applied widely. Our results showed that both Mix P and gsbay could accurately estimate single-nucleotide polymorphism(SNP) marker effects, and thereby could be applied for the analysis of genomic estimated breeding values(GEBV). In simulated data from different scenarios, the accuracy of GEBV acquired was ranged from 0.20 to 0.78 by Mix P; it was ranged from 0.21 to 0.67 by gsbay; and it was ranged from 0.21 to 0.61 by GBLUP. Estimations made by Mix P and gsbay were expected to be more reliable than those estimated by GBLUP. Predictions made by gsbay were more robust, while with Mix P the computation is much faster, especially in dealing with large-scale data. These results suggested that both algorithms implemented by Mix P and gsbay are feasible to carry out genomic selection in scallop breeding, and more genotype data will be necessary to produce genomic estimated breeding values with a higher accuracy for the industry. 展开更多
关键词 GENOMIC selection SCALLOP BREEDING method comparison
下载PDF
Analysis and Research on Interchange and Expansion options of Expressway
8
作者 Yaoping Luo 《Journal of World Architecture》 2023年第4期64-74,共11页
China's road network consists of numerous older expressways experiencing high traffic volumes and severe congestion,necessitating urgent reconstruction and expansion efforts.This study discusses the reconstruction... China's road network consists of numerous older expressways experiencing high traffic volumes and severe congestion,necessitating urgent reconstruction and expansion efforts.This study discusses the reconstruction and expansion project of the Yinkun Expressway's Chongqing High-tech Zone to Rongchang District section,with a detailed exploration of the entire design process.Through a comprehensive analysis,the strengths and weaknesses of different plans are examined,so as to determine the optimal plan.The design chosen saves costs while effectively addressing traffic demands.Additionally,the study summarizes the valuable design insights gained from this interchange transformation,aiming to provide valuable reference for similar interchange projects in the future. 展开更多
关键词 EXPRESSWAY comparison and selection of expressway interchange reconstruction and expansion designs
下载PDF
An approach for choosing discretization schemes and grid size based on the convection-diffusion equation
9
作者 Lin ZHOU Zhenghong GAO Yuan GAO 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2018年第6期877-890,共14页
A new approach for selecting proper discretization schemes and grid size is presented. This method is based on the convection-diffusion equation and can provide insight for the Navier-Stokes equation. The approach mai... A new approach for selecting proper discretization schemes and grid size is presented. This method is based on the convection-diffusion equation and can provide insight for the Navier-Stokes equation. The approach mainly addresses two aspects, i.e., the practical accuracy of diffusion term discretization and the behavior of high wavenum- ber disturbances. Two criteria are included in this approach. First, numerical diffusion should not affect the theoretical diffusion accuracy near the length scales of interest. This is achieved by requiring numerical diffusion to be smaller than the diffusion discretization error. Second, high wavenumber modes that are.much smaller than the length scales of interest should not be amplified. These two criteria provide a range of suitable scheme combinations for convective flux and diffusive flux and an ideal interval for grid spacing. The effects of time discretization on these criteria are briefly discussed. 展开更多
关键词 convection-diffusion equation cell ReynOlds number diffusion term accu-racy high wavenumber mode scheme selection
下载PDF
Comparison and Selection of Water Restoration Techniques for Artificial Landscape Lakes in Nantong City
10
作者 Shengrong YAN Yuyue MA +2 位作者 Yi'an CHEN Jiafeng SUN Mingqing CHEN 《Agricultural Biotechnology》 2024年第3期90-92,95,共4页
As an important part of urban infrastructure,urban water system is of great and far-reaching significance for ensuring urban flood control and waterlogging safety,protecting ecological environment and building livable... As an important part of urban infrastructure,urban water system is of great and far-reaching significance for ensuring urban flood control and waterlogging safety,protecting ecological environment and building livable homes.Taking the urban water system of Nantong as an example,Nantong Water Resources Bureau issued R evision of Nantong Urban Water System Planning in 2017,and put forward the construction of the"two circles,eight lakes and nine veins"water system layout,giving new vitality to the urban water system.In view of problems existing in newly excavated artificial landscape lakes,such as fragile water ecosystem,strong eutrophication trend,poor environmental sensory effect and unsatisfactory water landscape effect,it is urgent to study the in-situ water ecological restoration technique of"algae-controlling zooplankton+submerged plant community"to build a"grass-type clear water"ecosystem for artificial landscape lakes,so as to improve the water sensory index and self-purification ability and finally realize the double improvement of"sensory effect and water quality"of artificial landscape lakes. 展开更多
关键词 Water body remediation technique Artificial landscape lake comparison and selection Nantong City
下载PDF
Edge Computing-Based Joint Client Selection and Networking Scheme for Federated Learning in Vehicular IoT 被引量:4
11
作者 Wugedele Bao Celimuge Wu +3 位作者 Siri Guleng Jiefang Zhang Kok-Lim Alvin Yau Yusheng Ji 《China Communications》 SCIE CSCD 2021年第6期39-52,共14页
In order to support advanced vehicular Internet-of-Things(IoT)applications,information exchanges among different vehicles are required to find efficient solutions for catering to different application requirements in ... In order to support advanced vehicular Internet-of-Things(IoT)applications,information exchanges among different vehicles are required to find efficient solutions for catering to different application requirements in complex and dynamic vehicular environments.Federated learning(FL),which is a type of distributed learning technology,has been attracting great interest in recent years as it performs knowledge exchange among different network entities without a violation of user privacy.However,client selection and networking scheme for enabling FL in dynamic vehicular environments,which determines the communication delay between FL clients and the central server that aggregates the models received from the clients,is still under-explored.In this paper,we propose an edge computing-based joint client selection and networking scheme for vehicular IoT.The proposed scheme assigns some vehicles as edge vehicles by employing a distributed approach,and uses the edge vehicles as FL clients to conduct the training of local models,which learns optimal behaviors based on the interaction with environments.The clients also work as forwarder nodes in information sharing among network entities.The client selection takes into account the vehicle velocity,vehicle distribution,and the wireless link connectivity between vehicles using a fuzzy logic algorithm,resulting in an efficient learning and networking architecture.We use computer simulations to evaluate the proposed scheme in terms of the communication overhead and the information covered in learning. 展开更多
关键词 vehicular IoT federated learning client selection networking scheme
下载PDF
High-end equipment development task decomposition and scheme selection method 被引量:3
12
作者 XU Xiangqian YANG Kewei +3 位作者 DOU Yajie ZHOU Zhexuan CHEN Ziyi TAN Yuejin 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2021年第1期118-135,共18页
Decomposition of tasks and selection of optimal schemes are key procedures in high-end equipment development processes.However,such procedures are highly innovative,technology intensive,interdisciplinary,and multi-par... Decomposition of tasks and selection of optimal schemes are key procedures in high-end equipment development processes.However,such procedures are highly innovative,technology intensive,interdisciplinary,and multi-party engineering projects,making the decomposition and scheme selection more difficult and complicated than that in the development of ordinary equipment.In this study,we consider three factors,namely,functional structure,task granularity,and task feasibility in task decomposition of high-end equipment development.Based on the principles of systems engineering,a method of task decomposition is proposed.As for decomposition scheme selection,a method based on the superiority and inferiority ranking(SIR)method mixed information and multiple attribute decision making is proposed by considering attributes of scheme feasibility,uncertainty risk and task integration complexity.To verify the proposed method,development of a military electric vehicle is used as an example to demonstrate the calculation process. 展开更多
关键词 high-end equipment task decomposition decomposition scheme selection
下载PDF
Protection of Distributed Generation: Challenges and Solutions 被引量:1
13
作者 Umair Shahzad Salman Kahrobaee Sohrab Asgarpoor 《Energy and Power Engineering》 2017年第10期614-653,共40页
Distributed generation (DG) is the future of energy. This technology allows the bidirectional flow of power within an electrical network. Researchers are faced with many challenges to the accurate implementation of pr... Distributed generation (DG) is the future of energy. This technology allows the bidirectional flow of power within an electrical network. Researchers are faced with many challenges to the accurate implementation of protection schemes for DG-connected distribution network. The schemes designed must satisfy the performance requirements of selectivity, reliability, and sensitivity. Most researchers opine that conventional protection schemes based on over current detection are insufficient to completely and accurately protect a DG-connected distributed power system. There are many challenges?that?need to be tackled before embarking upon the journey to successfully implement these schemes. This paper summarizes the major challenges which one can encounter while designing protection schemes for DG-connected distribution networks. Some possible solutions from the literature are also mentioned. Moreover, a suggested solution for protecting future active distribution networks is provided. It is expected that this paper will act as a benchmark for future researchers in this field to tackle the challenges related to the protection of active distribution networks. 展开更多
关键词 Distributed Generation (DG) Energy SELECTIVITY Sensitivity RELIABILITY PROTECTION schemes ACTIVE Distribution Networks
下载PDF
Comparison of capacities at road intersections
14
作者 冯树民 张凤霖 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2010年第4期467-470,共4页
In order to research the capacity differences of road intersections,this paper analyzed the influence factors and calculation models of various types of capacity at intersections and then obtained simplified models th... In order to research the capacity differences of road intersections,this paper analyzed the influence factors and calculation models of various types of capacity at intersections and then obtained simplified models through reasonable assumption. 2 /2,4 /2,4 /4 intersections at which saturation and forecasted traffic volume were given were taken as examples,and an appropriate type was selected through capacity comparison. This paper can give a predictive estimation of the intersection capacity and provides theoretical data for the type selection of intersections. 展开更多
关键词 INTERSECTION type selection capacity comparison simplified model
下载PDF
Optimal Selection Model of Equipment Design Scheme Based on Set Pair Analysis
15
作者 赵劲松 康建设 +1 位作者 张春润 贺宇 《Journal of Donghua University(English Edition)》 EI CAS 2015年第6期982-985,共4页
Selecting the optimal one from similar schemes is a paramount work in equipment design.In consideration of similarity of schemes and repetition of characteristic indices,the theory of set pair analysis(SPA)is proposed... Selecting the optimal one from similar schemes is a paramount work in equipment design.In consideration of similarity of schemes and repetition of characteristic indices,the theory of set pair analysis(SPA)is proposed,and then an optimal selection model is established.In order to improve the accuracy and flexibility,the model is modified by the contribution degree.At last,this model has been validated by an example,and the result demonstrates the method is feasible and valuable for practical usage. 展开更多
关键词 set pair analysis(SPA) equipment design scheme optimal selection model nearness degree
下载PDF
A Genetic Fuzzy Analytical Hierarchy Process Based Projection Pursuit Method for Selecting Schemes of Water Transportation Projects 被引量:1
16
作者 JIN Juliang LI Lei +1 位作者 WANG Wensheng ZHANG Ming 《Journal of Ocean University of China》 SCIE CAS 2006年第4期289-294,共6页
The optimal selection of schemes of water transportation projects is a process of choosing a relatively optimal scheme from a number of schemes of water transportation programming and management projects, which is of ... The optimal selection of schemes of water transportation projects is a process of choosing a relatively optimal scheme from a number of schemes of water transportation programming and management projects, which is of importance in both theory and practice in water resource systems engineering. In order to achieve consistency and eliminate the dimensions of fuzzy qualitative and fuzzy quantitative evaluation indexes, to determine the weights of the indexes objectively, and to increase the differences among the comprehensive evaluation index values of water transportation project schemes, a projection pursuit method, named FPRM-PP for short, was developed in this work for selecting the optimal water transportation project scheme based on the fuzzy preference relation matrix. The research results show that FPRM-PP is intuitive and practical, the correction range of the fuzzy preference relation matrix [WTHX]A[WT] it produces is relatively small, and the result obtained is both stable and accurate; therefore FPRM-PP can be widely used in the optimal selection of different multi-factor decision-making schemes. 展开更多
关键词 调水工程 优化方案 遗传算法 模糊解析分层过程 投影寻踪法
下载PDF
MOF/CdS梯型光催化剂同时进行苯甲醇氧化和析氢反应及其机理研究
17
作者 刘博文 蔡家杰 +3 位作者 张建军 谭海燕 程蓓 许景三 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2023年第8期204-215,共12页
太阳能驱动的光催化水分解制氢是一种清洁、可持续的技术,可以减少碳排放.一般来说,光催化全解水的析氧半反应过程需要消耗四个空穴,且迟缓的反应动力学会抑制整体反应,因此光催化全解水极具挑战性.在光催化制氢中通常利用空穴牺牲剂来... 太阳能驱动的光催化水分解制氢是一种清洁、可持续的技术,可以减少碳排放.一般来说,光催化全解水的析氧半反应过程需要消耗四个空穴,且迟缓的反应动力学会抑制整体反应,因此光催化全解水极具挑战性.在光催化制氢中通常利用空穴牺牲剂来提升产氢半反应的效率.然而,这些过程会产生无用的氧化产物,造成光生空穴氧化能力的浪费,且增加了系统成本.因此,构建一个由光催化产氢和选择性有机合成相结合的双功能氧化还原体系,可同时利用光生电子和空穴,并且产物中氢气和高附加值的有机产品容易分离,因此具有较高的可持续经济效应.利用梯型异质结将两种带隙适合且能带结构匹配的光催化剂复合在一起,可以最大程度地利用两种光催化剂的氧化还原能力,为解决上述问题提供了一条理想途径.本文采用化学浴法将CdS纳米颗粒原位生长在锆基金属有机框架UiO-66-NH_(2)(U6N)上.在光照条件下,梯型异质结催化苯甲醇选择性氧化生成苯甲醛和氢气的性能大幅度提升,UC0.75(U6N/CdS理论质量比为0.75)复合物光照3 h产氢速率为630μmol·g^(-1)h^(-1),同时苯甲醇氧化为苯甲醛的选择性达到99%.原位辐照X射线光电子能谱结果表明,UC0.75梯型异质结界面的电子转移路径,在暗态下电子由CdS转移到U6N,在光照下电子由U6N转移到CdS.利用飞秒瞬态吸收(fs-TA)光谱进一步研究了异质结的载流子迁移的动力学信息,结果表明,复合样品中基态漂白信号衰减时间减少,梯型异质结界面处电子转移效率较高.此外,通过原位漫反射红外傅里叶变换光谱、电子顺磁共振和同位素实验揭示了苯甲醇的氧化机理,光照下,位于U6N的光生空穴与苯甲醇相互作用,先氧化苯甲醇上的α-C产生·CH(OH)Ph,然后进一步氧化产生苯甲醛,同时,CdS上的光生电子与水中产生的H+结合产生氢气.综上,本文通过飞秒瞬态吸收光谱(fs-TAS)光谱来阐述梯型异质结的电子转移机制,并为金属有机框架/无机物复合光催化剂的设计提供了借鉴. 展开更多
关键词 梯型异质结 光催化产氢 选择性有机氧化 超快光谱
下载PDF
A Simple Application and Design of Genetic Algorithm in Card Problem
18
作者 顾鹏程 《电脑知识与技术》 2016年第2Z期25-26,共2页
According to traditional card problem solving which is based on the idea of genetic algorithm(GA),a set of algorithms is designed to find final solution.For each process in genetic algorithm,including choices of fitne... According to traditional card problem solving which is based on the idea of genetic algorithm(GA),a set of algorithms is designed to find final solution.For each process in genetic algorithm,including choices of fitness function,parameters determination and coding scheme selection,classic algorithm is used to realize the various steps,and ultimately to find solution of problems. 展开更多
关键词 genetic algorithm card problem fitness function parameters determination coding scheme selection
下载PDF
跨海桥梁基础波浪力断面对比与研究 被引量:1
19
作者 崔苗苗 毕昕宇 +1 位作者 李鑫 祝兵 《铁道标准设计》 北大核心 2024年第2期80-85,92,共7页
桥梁基础在波浪环境下的施工安全关乎桥梁建设的稳定性,需要给予足够的重视。利用数值模拟手段,基于改进的RNG κ-ε模型,采用VOF法模拟自由液面,在保持相同迎浪断面的情况下,建立圆形、圆端形、矩形和多边形4种不同断面形式桥梁基础受... 桥梁基础在波浪环境下的施工安全关乎桥梁建设的稳定性,需要给予足够的重视。利用数值模拟手段,基于改进的RNG κ-ε模型,采用VOF法模拟自由液面,在保持相同迎浪断面的情况下,建立圆形、圆端形、矩形和多边形4种不同断面形式桥梁基础受波浪作用的三维数值模型,对比其受力差异,并结合流场数据加以分析。结果表明:相同波浪条件下4种不同断面形式的结构所受到水平波浪力中以圆形结构为最小,矩形结构为最大,其总水平波浪力幅值较圆形结构增大10%左右;桥梁基础结构在波浪的作用下,基础周围会受到绕流作用,使得结构部分位置处的流速增大并出现流速集中现象,在矩形结构周围这一现象最为突出,多边形结构的情况与之类似,而圆形及圆端形结构的流速集中现象则相对较弱;按规范计算得到的等效圆柱波浪力相较于数值模拟结果大23%~29%,按等效方柱计算得到的波浪力相较于数值模拟结果大10%~13%。从工程设计的角度看,采用圆弧形的结构设计有助于减小波浪荷载和削弱桥梁基础局部的流速增大与流速集中现象。 展开更多
关键词 跨海桥梁 桥梁基础 波浪力 结构比选 数值模拟
下载PDF
基于超效率DEA的地铁初近远期编组方案比选研究
20
作者 朱昌锋 王学贵 +2 位作者 刘康儒 安轲 周宏昌 《铁道标准设计》 北大核心 2024年第8期14-22,共9页
编组方案是实现不同时期地铁运营模式与客流特征相匹配的基础,也是直接影响地铁规划建设成本和低碳运营的关键问题。在综合分析影响地铁编组方案关键要素的基础上,构建了地铁初近远期编组方案比选的综合评价指标体系,以及编组方案比选... 编组方案是实现不同时期地铁运营模式与客流特征相匹配的基础,也是直接影响地铁规划建设成本和低碳运营的关键问题。在综合分析影响地铁编组方案关键要素的基础上,构建了地铁初近远期编组方案比选的综合评价指标体系,以及编组方案比选的两步筛选法;通过分析各指标对地铁编组方案影响的差异性,提出基于超效率DEA的地铁初近远期编组方案评价比选模型,并在对指标体系进行约简合并的基础上,从投入和产出两个角度对指标体系进行划分;最后,以实例验证和分析了地铁初近远期编组方案评价比选模型的可行性和合理性。算例分析结果表明:(1)固定编组方案属于成本赋能型方案,需较高的设备设施成本和运营投入;而更改编组方案属于技术赋能型方案,通过提高管理和技术水平,实现了运能匹配和乘客时间满意度等方面的有效产出;(2)更改编组方案和固定编组方案之间的优劣具有一定的动态性,需结合具体的线路条件、城市或企业财政情况、运营管理和技术水平等条件进行综合判断。本文提出的地铁初近远期编组方案比选理论方法适用于多种实践场景,具有一定的实用性,可为地铁初近远期编组方案比选的规范化提供一定的理论参考。 展开更多
关键词 地铁 编组方案 初近远期 超效率DEA 指标体系 方案比选
下载PDF
上一页 1 2 233 下一页 到第
使用帮助 返回顶部