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无控制交叉口车辆延误迭代计算法 被引量:3
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作者 冯树民 孙祥龙 《哈尔滨工业大学学报》 EI CAS CSCD 北大核心 2011年第4期63-66,共4页
无控制交叉口车辆延误对于评价交叉口服务水平有重要意义.为研究一种合乎实际的无控制交叉口延误的计算方法,分析了车辆的运行特征,将延误分为等待延误和加减速延误,利用概率理论推导了各进口的平均服务时间和服务时间方差的迭代计算方... 无控制交叉口车辆延误对于评价交叉口服务水平有重要意义.为研究一种合乎实际的无控制交叉口延误的计算方法,分析了车辆的运行特征,将延误分为等待延误和加减速延误,利用概率理论推导了各进口的平均服务时间和服务时间方差的迭代计算方法,用M/G/1排队系统描述排队现象,提出了交叉口的平均等待延误计算公式,借鉴信号交叉口加减速延误的分析方法,提出无控制交叉口加减速延误的计算方法.对哈尔滨市十字街与宣威街十字型无控制交叉口进行调查,利用实测数据对理论计算结果进行检验,平均相对误差较小,理论值与实测值吻合较好. 展开更多
关键词 无控制交叉口 车辆延误 迭代计算法 M/G/1排队系统 等待延误
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迭代法在高温高压井套管柱设计计算中的应用
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作者 杨明合 夏宏南 《钻采工艺》 CAS 2002年第1期65-67,共3页
针对高温高压井套管柱校核计算的特殊性和出现的问题 ,采用迭代法进行套管柱强度校核计算。计算结果完全满足校核计算的要求。这种计算方法不仅适合套管柱的强度校核计算 。
关键词 迭代计算法 高温高压 套管柱 设计 计算 石油钻井
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用迭代法计算明渠均匀流水深和临界水深 被引量:3
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作者 葛节忠 陈雪峰 黄建平 《水利水电技术》 CSCD 北大核心 2006年第1期75-78,共4页
针对明流水力计算中人工渠道均匀流水深h0和临界水深hk用试算法和查图法计算繁琐,查算精度较低等问题,本文提出了迭代计算方法,并完整地介绍了几种常用规则过水断面明流的均匀流水深和临界水深的迭代计算关系式和算例。
关键词 明渠 均匀流水深 临界水深 迭代计算法
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A New Technique for Constructing Higher-order Iterative Methods to Solve Nonlinear Systems
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作者 XIAO Xiaoyong 《应用数学》 北大核心 2025年第3期762-774,共13页
In this paper,a new technique is introduced to construct higher-order iterative methods for solving nonlinear systems.The order of convergence of some iterative methods can be improved by three at the cost of introduc... In this paper,a new technique is introduced to construct higher-order iterative methods for solving nonlinear systems.The order of convergence of some iterative methods can be improved by three at the cost of introducing only one additional evaluation of the function in each step.Furthermore,some new efficient methods with a higher-order of convergence are obtained by using only a single matrix inversion in each iteration.Analyses of convergence properties and computational efficiency of these new methods are made and testified by several numerical problems.By comparison,the new schemes are more efficient than the corresponding existing ones,particularly for large problem sizes. 展开更多
关键词 Systems of nonlinear equation Order of convergence Higher-order method Extended Newton iteration Computational efficiency
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反相高效液相色谱中死时间的测定 被引量:2
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作者 马桂英 孙科夫 朱明华 《华东理工大学学报(自然科学版)》 CAS CSCD 1994年第6期829-833,共5页
采用不同极性的同系物,通过迭代计算法计算了反相液相色谱的死时间,并与用探测物直接测定法所得结果进行了比较,两者基本一致。采用同系物计算得到的死时间能反映出有机溶剂吸附层对死体积的影响。同系物的极性对死时间存在影响。用... 采用不同极性的同系物,通过迭代计算法计算了反相液相色谱的死时间,并与用探测物直接测定法所得结果进行了比较,两者基本一致。采用同系物计算得到的死时间能反映出有机溶剂吸附层对死体积的影响。同系物的极性对死时间存在影响。用弱极性的烷基苯同系物求得的死时间略大于用非极性的正构烷烃所求得的死时间。 展开更多
关键词 死时间 高效液相色谱 迭代计算法
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淮北平原地下水埋深变化对气候变化的响应及预测 被引量:10
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作者 鞠琴 刘小妮 +4 位作者 刘智天 高慧滨 赵雯颉 尼玛扎西 郝文龙 《农业工程学报》 EI CAS CSCD 北大核心 2022年第7期136-145,共10页
分析气候变化下的地下水埋深变化对区域未来的水资源利用和长期规划有着重要的意义。该研究利用五道沟水文实验站实测资料,分析淮北平原地下水埋深历史变化,在评估考虑了潜水蒸发的地下水埋深迭代算法在淮北平原的适用性的基础上,以CMIP... 分析气候变化下的地下水埋深变化对区域未来的水资源利用和长期规划有着重要的意义。该研究利用五道沟水文实验站实测资料,分析淮北平原地下水埋深历史变化,在评估考虑了潜水蒸发的地下水埋深迭代算法在淮北平原的适用性的基础上,以CMIP5中三种气候模式的未来降水为主要影响因子,通过多模式集成方法,预估未来气候变化下淮北平原地下水埋深变化。结果表明:淮北平原地下水埋深年际变化波动较大,多年平均地下水埋深在季节上表现为春季(2.52 m)>冬季(2.49 m)>秋季(2.21 m)>夏季(2.17 m),空间上整体呈由北向南逐渐变浅的变化趋势;考虑了潜水蒸发的地下水埋深迭代算法对淮北平原地下水埋深变化趋势的模拟结果与实际变化趋势基本一致;在RCP4.5情景下,未来降水量将持续增加的影响,地下水埋深年内月变化先降低后增加,7月最浅为0.73 m,1月最深为4.22 m;季节变化夏季最浅0.94 m,冬季最深为3.98 m,但年变化整体呈下降趋势,起伏相对较小。研究结果对合理调控区域水资源及水环境保护具有重要的借鉴和指导意义。 展开更多
关键词 气候变化 降水 地下水埋深 叶水庭公式 迭代计算法 淮北平原
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A modified method to calculate reliability index using maximum entropy principle 被引量:3
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作者 徐志军 郑俊杰 +1 位作者 边晓亚 刘勇 《Journal of Central South University》 SCIE EI CAS 2013年第4期1058-1063,共6页
Routine reliability index method, first order second moment (FOSM), may not ensure convergence of iteration when the performance function is strongly nonlinear. A modified method was proposed to calculate reliability ... Routine reliability index method, first order second moment (FOSM), may not ensure convergence of iteration when the performance function is strongly nonlinear. A modified method was proposed to calculate reliability index based on maximum entropy (MaxEnt) principle. To achieve this goal, the complicated iteration of first order second moment (FOSM) method was replaced by the calculation of entropy density function. Local convergence of Newton iteration method utilized to calculate entropy density function was proved, which ensured the convergence of iteration when calculating reliability index. To promote calculation efficiency, Newton down-hill algorithm was incorporated into calculating entropy density function and Monte Carlo simulations (MCS) were performed to assess the efficiency of the presented method. Two numerical examples were presented to verify the validation of the presented method. Moreover, the execution and advantages of the presented method were explained. From Example 1, after seven times iteration, the proposed method is capable of calculating the reliability index when the performance function is strongly nonlinear and at the same time the proposed method can preserve the calculation accuracy; From Example 2, the reliability indices calculated using the proposed method, FOSM and MCS are 3.823 9, 3.813 0 and 3.827 6, respectively, and the according iteration times are 5, 36 and 10 6 , which shows that the presented method can improve calculation accuracy without increasing computational cost for the performance function of which the reliability index can be calculated using first order second moment (FOSM) method. 展开更多
关键词 reliability index maximum entropy principle first order second moment Newton iteration Monte Carlo simulation
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Inverse kinematics of a heavy duty manipulator with 6-DOF based on dual quaternion 被引量:8
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作者 王恒升 占德友 +1 位作者 黄平伦 陈伟锋 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第7期2568-2577,共10页
An iterative method is introduced successfully to solve the inverse kinematics of a 6-DOF manipulator of a tunnel drilling rig based on dual quaternion, which is difficult to get the solution by Denavit-Hartenberg(D-H... An iterative method is introduced successfully to solve the inverse kinematics of a 6-DOF manipulator of a tunnel drilling rig based on dual quaternion, which is difficult to get the solution by Denavit-Hartenberg(D-H) based methods. By the intuitive expression of dual quaternion to the orientation of rigid body, the coordinate frames assigned to each joint are established all in the same orientation, which does not need to use the D-H procedure. The compact and simple form of kinematic equations, consisting of position equations and orientation equations, is also the consequence of dual quaternion calculations. The iterative process is basically of two steps which are related to solving the position equations and orientation equations correspondingly. First, assume an initial value of the iterative variable; then, the position equations can be solved because of the reduced number of unknown variables in the position equations and the orientation equations can be solved by applying the solution from the position equations, which obtains an updated value for the iterative variable; finally, repeat the procedure by using the updated iterative variable to the position equations till the prescribed accuracy is obtained. The method proposed has a clear geometric meaning, and the algorithm is simple and direct. Simulation for 100 poses of the end frame shows that the average running time of inverse kinematics calculation for each demanded pose of end-effector is 7.2 ms on an ordinary laptop, which is good enough for practical use. The iteration counts 2-4 cycles generally, which is a quick convergence. The method proposed here has been successfully used in the project of automating a hydraulic rig. 展开更多
关键词 heavy-duty manipulator dual quaternion robotic kinematics inverse kinematics(IK) iterative algorithm tunnel drilling rig
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An accelerated scheme with high quality mesh based on Lloyd iteration 被引量:1
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作者 秦衡峰 王艺 +1 位作者 李明富 周后明 《Journal of Central South University》 SCIE EI CAS 2012年第10期2797-2802,共6页
High quality mesh plays an important role for finite element methods in science computation and numerical simulation.Whether the mesh quality is good or not,to some extent,it determines the calculation results of the ... High quality mesh plays an important role for finite element methods in science computation and numerical simulation.Whether the mesh quality is good or not,to some extent,it determines the calculation results of the accuracy and efficiency.Different from classic Lloyd iteration algorithm which is convergent slowly,a novel accelerated scheme was presented,which consists of two core parts:mesh points replacement and local edges Delaunay swapping.By using it,almost all the equilateral triangular meshes can be generated based on centroidal Voronoi tessellation(CVT).Numerical tests show that it is significantly effective with time consuming decreasing by 40%.Compared with other two types of regular mesh generation methods,CVT mesh demonstrates that higher geometric average quality increases over 0.99. 展开更多
关键词 Lloyd iteration mesh generation Delaunay triangulation high quality mesh centroidal Voronoi tessellation
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