An improved model updating method of reduced-models for finite element model

Most of exiting model updating methods based on the substructure matrices did not consider the effect of model reduction process on model updating which led to the updating results could not become more and more accurate with the improvement of the model reduction precision and the convergence rate was greatly reduced. In order to solve this problem, this paper analyses the basic reason about this problem, and proposes an improved model updating method of reduced-models, named as improved reduced cross-model cross-mode (IRCMCM) method. The proposed method eliminates the disadvantageous effect by adding a correction term to the model updating formula and employing an iterative process. The results obtained by the referenced method and IRCMCM method are compared by numerical examples of satellite’s plates, which indicate the model updating results are more accurate by using the proposed method, and the model updating precision becomes better with the precision of the model reduction upgraded and the convergence rate is improved to a large extent at the same time.     

桥梁结构非线性模型修正研究综述

针对桥梁服役期间由于结构力学性能减弱从而表现出具有时变特征的非线性振动问题,在回顾非线性模型修正发展的基础上,分别从非线性系统识别、非线性模型修正方法和非线性模型不确定性量化3个方面入手,总结了结构非线性模型修正技术中存在的一些关键问题;结合复杂结构损伤识别、性能评估与安全监测等内容,对其在桥梁结构中的应用展开了讨论。研究结果表明:以固有频率和模态振型为代表的响应特征量仅能反映时不变结构的物理特性,对于非线性结构而言其力学性能随外激励作用而不断变化,基于线性系统特征量的模型修正方法不能很好地适用于具有明显时变特性的非线性结构;结构动力响应主分量的瞬时频率和瞬时幅值包含了振动响应信号的相位信息和幅值信息,可以较为全面地反映动力荷载作用下结构响应的非平稳特性,选择具有时变特性的瞬时特征量来构建目标函数能够更为合理地表征非线性结构的动力特性;不确定性模型修正方法通过综合利用实测响应数据,考虑了测量噪声、模型误差和数值计算方法等不确定因素的影响,提高了模型修正结果的准确性;复杂结构非线性模型修正过程中涉及的参数众多,计算量大,极大地限制了其在实际工程结构中的应用,因此,合理选择具有代表性的非线性模型参数以及提高模型修正的计算效率是当前亟需解决的问题。      

一种“效率-公平-运力”多维权衡的需求可拆分配送方法

针对自然灾害及重大社会公共事件等各类突发事件的配送问题，本文以公路运输为研究场景，将配送时间最短、加权时间攀比值最小和使用车辆数最少为多维目标，在引入需求可拆分这一限制条件的基础上，构建“效率-公平-运力”多维权衡的需求可拆分应急物资配送模型。针对该问题设计改进的蚁群算法求解模型。从选择拆分点、信息素更新和引入变邻域搜索算子这3个方面改进了算法，并实现当解持续不变时，初始化信息素，以增加随机性。结果表明，与传统求解算法相比，改进算法的稳定性更高(平均偏差率降低7.00%)，寻优性更好(优化率提高7.41%)。 通过分析考虑三目标、双目标和决策者具有明显偏好的多重场景下的求解结果得知：效率、公平、 运力这3个子目标相互悖反，增加运力投入可以显著提高配送方案的效率与公平；当运力不变时，效率与公平之间近似呈同比例反比关系。研究结论可为救灾目标不确定条件下多因素考量的应急物资配送决策生成与优化问题提供方法改进与可量化决策支撑。     

基于新一代信息技术的农村公路基础设施数据更新管理系统功能架构研究

为了提升农村公路基础设施更新数据准确性及更新工作的管理效率,分析了当前农村公路建设规划政策、部级与省级农村公路管理流程;梳理了已有更新系统的部署现状;通过对系统功能框架的分析,总结了现有系统与新时代农村公路建设更新需求的差距;归纳了前沿信息技术对农村公路基础设施更新的促进与推动作用。在此基础上,提出了适用于新时代农村公路发展建设、充分利用新一代信息技术优势的信息耦合链式农村公路基础设施数据更新管理系统功能架构;同时提出了基于此功能架构的系统功能流程与系统模块详细架构。较之现有系统,新架构能够提升对更新数据的分析解译能力与管理部门的相关工作效率,提升农村公路基础设施数据更新能力。     

三维水流作用下哑铃型围堰周围海床局部冲刷

为研究跨海桥梁施工过程中围堰周围海床的局部冲刷深度与冲刷坑形态,运用有限差分软件Flow-3D建立了水流作用下哑铃型围堰周围海床冲刷的三维数值模型.对新建模型的精度进行了验证,基于此模型研究了哑铃型围堰周围的流场特征及吃水深度、流速对围堰周围海床局部冲刷深度的影响.研究结果表明:受围堰与钢护筒影响,围堰周围流场特征比较紊乱;随着吃水深度与流速的增加,哑铃型围堰周围海床的冲刷深度逐渐增大,当吃水深度为12.88 m,流速大小为4 m/s时,围堰周围最大冲刷深度接近8 m,然而与流速相比,吃水深度对哑铃型围堰周围海床冲刷深度的影响相对较小,围堰吃水深度由6.88 m增加到15.88 m时,最大冲刷深度增加不超过25%;最大冲刷深度发生在靠近围堰中心线的钢护筒附近;冲刷坑平面形态与围堰形状类似,围堰周围海床冲刷范围受流速影响较大,而受围堰吃水深度影响较小.      

导航电子地图中道路网增量信息的多尺度探测

针对常用增量信息提取方法中根据经验阈值确定新旧目标匹配的不足,提出一种导航电子地图中道路网增量信息的多尺度探测方法.该方法用最大类间方差法自适应地确定几何匹配阈值来探测增量信息,完善了基于道路网眼密度的增量变化目标渐进式选取算法,实现了增量信息在较小比例尺下的缩编提取.增量信息探测实验研究结果表明:基于自适应匹配阈值的新旧版本对应路网目标匹配准确率达到了90%,优于传统的经验阈值匹配精度;改进的增量变化目标渐进式选取算法可以满足路网增量更新的结构选取需求.      

Application of Classical Transportation Methods for Solving Fuzzy Transportation Problems

There are several methods, in the literature, for finding a fuzzy optimal solution to fully fuzzy transportation problems (transportation problems in which all the parameters are represented by fuzzy numbers). In this study, the shortcomings of some existing methods are pointed out, and to overcome these shortcomings, two new methods (based on fuzzy linear programming formulation and classical transportation methods) are proposed to find a fuzzy optimal solution to fuzzy transportation problems with a new representation of trapezoidal fuzzy numbers. The advantages of the proposed methods over existing methods are discussed. Also, it is shown that it is better to use the proposed representation of trapezoidal fuzzy numbers instead of the existing representation of trapezoidal fuzzy numbers for finding a fuzzy optimal solution to fuzzy transportation problems. To illustrate the proposed methods, a fuzzy transportation problem (FTP) is solved using the proposed methods and the obtained results are discussed. The proposed methods are easy to understand and to apply for finding a fuzzy optimal solution to fuzzy transportation problems occurring in real-life situations.     

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既有文献中关于求解模糊交通问题（所有参数均为模糊数据）的模糊最优解的方法有多种。本文在分析现有方法缺点的基础上,提出了两种方法用于求解具有梯形模糊数的模糊交通问题,其基于模糊线性规划和经典交通方法。同时论证了这两种方法不同于现有方法的优势。通过算例阐述本文方法求解模糊交通问题的过程并分析了求解结果。所提出的方法易于理解且在求解模糊交通问题最优解问题上具有良好的应用前景。     

Application of PETSc in soil-water coupled geotechnical problems

In this paper, parallel library, portable extensible toolkit for scientific computation (PETSc), is used to solve linear systems in soil-water coupled finite element method (FEM) for geotechnical problems. The parallel environment is integrated into GLEAVES, which is a geotechnical software package used for the finite element simulation. The linear system ·· = · which is a fundamental and the most time-consuming part of the FEM is solved with iterative solvers in PETSc. In order to find a robust and effective combination of iterative solvers and corresponding preconditioners for the soil-water coupled problems, performance evaluations on Krylov subspace methods and four preconditioners are carried out. The results indicate that general minimal residual (GMRES) method coupled with preconditioners can provide an effective solution. The application to a construction project is presented to illustrate the potential of the proposed solution.     

平衡接线牵引变压器同相供电下的容量设计方法

为了给同相供电系统牵引变压器容量选择提供理论依据,在既有异相牵引供电系统设计方法的基础上,分析了同相供电系统馈线电流与既有牵引供电系统馈线电流的差异,并针对既有线改造和新线建设两种情况提出同相供电系统牵引变压器容量设计方法.通过既有线和新建线路实现同相供电系统两个算例,说明新建线路和既有线牵引变压器容量可降低1~2个容量等级,并有效提高牵引供电系统运行经济性.      

基于蚂蚁算法的动态分布式路由算法

提出了一种利用蚂蚁算法进行动态更新分布式路由表的方法,该方法以路由表中的信息素强度和当时链路的负载状况为基础,来选择路由和更新路由表,给出了更新路由表的规则并利用计算机进行了仿真验证.仿真结果表明,蚂蚁算法可兼顾路由长度和网络负载两方面的因素,其选路效果优于传统动态分布式算法.     

基于LLE和LS_SVM的胃粘膜肿瘤细胞图像分类

胃粘膜肿瘤细胞图像的复杂性,组织器官形状的不规则性以及不同细胞的差异性,使得采用一般的线性分类方法对其进行分类很困难,结合局部线性嵌入（LLE）在处理非线性数据及最小二乘支持向量机（LS_SVM）在处理小样本、高维数及泛化问题方面的优势,文章提出一种基于LLE＋LS_SVM的胃粘膜肿瘤细胞图像分类方法,并采用LS_SVM的线性拟合误差来判断实验效果,最后比较本文方法与其他分类方法的优越性。实验结果表明,该方法在分类准确率和运行时间方面都有很大的优势。     

基于参数更新的体外索张力识别方法

以有限元分析模型参数更新理论为基础,提出了一种通过测试自振频率得到体外索张力的新方法,其参数更新的目标是使试验实测体外预应力体系的频率与有限元模型计算所得频率最为接近,进而识别出体外索张力大小,经实例验证,用所提出的方法来识别体外索的张力具有很高的精度．     

General precoder design for mitigation of intercarrier interference in OFDM mobile systems

For orthogonal frequency-division multiplexing （OFDM） communication systems, the frequency offset in mobile radio channels distorts the orthogonality between sub-carriers, which results in Intercarrier Interference（ICI） and seriously degrades the performance of systems. Based on ICI coefficients analysis, a novel preceder design scheme is proposed for mitigation of ICI. In this technique, preceder matrix is designed by the way of linear counteraction and inserted in the former transmitter signal. Computer simulation results show that this new scheme can effectively reduce ICI and significantly provide the carrier-interference power ratio improvement. Compared with existing ICI mitigation schemes with channel estimation, the proposed scheme has lower computational complexity, and compared with self- cancellation scheme, the bandwidth efficiency can be improved in this proposed scheme. The proposed scheme also has better convergence stability for time-varying frequency selective fading channel.     

基于DACS3的改进蚁群算法求解TSP问题

蚁群算法是优化领域中新出现的一种仿生进化算法。该算法采用分布式并行计算机制,具有较强的鲁棒性,易与其他算法结合,但存在运行时间长,容易陷入局部最优解,导致出现停滞现象等缺点。针对蚁群算法,首先介绍其基本原理及不足之处。随后提出了一种改进算法,该算法在选择路径时仅考虑信息素强度,在信息素强度更新时采用基于3层动态信息素更新(Dynamic Ant Colony System with 3 level updates,DACS3)机制,更好地模仿了自然蚂蚁。最后通过仿真验证该算法,结果表明该算法可以取得较好的搜索效果。     

A New Approach to Evidence Combination and Its Application to Targets Recognition in Image Sequence

The classical Dempster's combination rule is the most popular rule of combinations,but it is a poor solution for the management of the evidence conflict at the normalization step.When deal with high conflict information it can even involve counter-intuitive results.Based on evidence distance,some inherent characters of evidences are extracted,and discount method to combine conflicting evidence was proposed.The discount method can be also used to fuse image sequences to recognize targets.Examples show that the proposed method can provide reasonable results with good convergence efficiency.     

Code-aided interference suppression in direct sequence spread spectrum systems with eigenvector sign spreading code

For direct sequence spread spectrum (DSSS) communication systems suffering interference, it is known that code-aided interference suppression technique outperforms all of the previous linear or nonlinear methods. In this paper, we proposed an improved code-aided technique which can improve the system performance greatly by using the eigenvector sign (EVS) spreading sequence which depends on the statistical characteristics of the interference and the thermal noise. Foundation item: the National Natural Science Foundation of China (No. 60772100)     

既有桥梁的贝叶斯网络评估方法

结合贝叶斯网络的因果关系推理能力，将其用于对结构技术状态的推断，采用高斯贝叶斯网络对既有桥梁的评价方面作了初步的尝试．根据先验的各变量的统计特征，在找出各变量的因果关系、构建相应的贝叶斯网络后，即可以从观测到的信息中推断结构的技术状况，这对现有桥梁的评估具有实际意义．文中提出了既有桥梁的贝叶斯网络的构建和推理运算方法．并利用桥梁中受弯构件的安全度作为实例给出了说明．     

省级基础空间要素数据库联动更新的设计与实现

以某省为例,利用GIS技术设计与开发了基础空间要素数据库联动更新系统,阐述了系统的总体设计及系统所实现的功能。系统的建立实现多比例尺间各个要素更新的联动,保证了数据库中地理对象的完整性和数据的一致性,从而为数据库的检索、查询以及分析应用提供方便。     

列控车载设备控制程序及参数远程实时更新方法

针对既有列车控制系统不具备对车载设备控制程序及参数进行远程在线实时更新功能的问题,提出一种基于无线传输和嵌入式的列控车载设备控制程序与参数实时更新方法,在无线机车信号实际应用测试中表明,所实现的程序更新机制具有较高的适应性和可靠性,可有效提高运营中的车载设备程序升级效率,提高了对列车控制的安全性,降低了系统维护成本.