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复合三角Bezier曲面和平面的求交及其应用 被引量:8
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作者 李际军 柯映林 程耀东 《汽车工程》 EI CSCD 北大核心 2000年第2期120-124,共5页
本文提出了一种根据组成复合三角Bezier曲面的各三角Bezier曲面片与平面的相交类型,采用不同方法求取初始交点;通过迭代求精、求近曲面点和边界点计算,由一个初始交点顺序跟踪出整条交线的方法。这种包括各曲面片边界点的交线计算方法... 本文提出了一种根据组成复合三角Bezier曲面的各三角Bezier曲面片与平面的相交类型,采用不同方法求取初始交点;通过迭代求精、求近曲面点和边界点计算,由一个初始交点顺序跟踪出整条交线的方法。这种包括各曲面片边界点的交线计算方法可处理复合曲面与平面间形成多条交线、交线环的情况,所得到的交点记录了坐标值和相应曲面片的参数值。测试显示这种交线计算方法简单可靠,精度高,在自由曲面数控加工编程中具有广泛的应用场合,对提高汽车等领域的自由曲面NC加工精度具有重要的工程价值。 展开更多
关键词 复合三角Bezier曲面 NC加工 汽车 交线计算
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土方边坡开挖CAD辅助设计 被引量:2
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作者 刘立昌 《测绘技术装备》 2014年第4期32-34,23,共4页
在房屋建筑、铁路公路工程边坡施工中,边坡顶线的确定是土方施工工作的关键,应用土方边坡开挖CAD辅助设计可以快速方便地解决此类问题。根据一具体工程实例,介绍了边坡施工中,土方边坡开挖CAD辅助设计方法。
关键词 计算线 断面图 数字高程模型 设计坡比
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Route choice models based on altering OD
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作者 裴玉龙 郎益顺 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2003年第4期367-370,共4页
The condition and physical sense of actual dynamic user optimum are explained by analyzing a simple road network route choice. To match the practical application requirements, assignment network and simulation network... The condition and physical sense of actual dynamic user optimum are explained by analyzing a simple road network route choice. To match the practical application requirements, assignment network and simulation network are classified account for varying flowing loading. Instantaneous dynamic user optimum model should be applied to the former and actual dynamic user optimum model the latter respectively. The two model’s feasibility is studied as well. Considering the application in ATMS, the model is mainly used to analyze the altering OD problem. Moreover, it adds the method of route adapting into the object function selection to appraise elastic trip strategy and set up real means of route inducement. 展开更多
关键词 altering OD dynamic traffic assignment instantaneous dynamic user optimum actual dynamic user optimum
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Bus coordination holding control for transit hubs under APTS
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作者 滕靖 赵明 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2009年第1期131-137,共7页
To increase the passenger transferring efficiency, the bus coordination holding control for transit hubs, which is as an important dynamic dispatching method for improving the service level of transit hubs, was studie... To increase the passenger transferring efficiency, the bus coordination holding control for transit hubs, which is as an important dynamic dispatching method for improving the service level of transit hubs, was studied in the framework of bus coordination dispatching mode. Firstly, the bus coordination holding control flow was studied based on Advanced Public Transportation Systems (APTS) environment. Then a control model was presented to optimize the bus vehicle holding time, and a genetic algorithm was designed as the solving method. In the end, an example was given to illustrate the effectiveness of the control strategy and the algorithm. 展开更多
关键词 public transport system holding control transit hub coordination dispatching
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A modified BFGS algorithm based on a hybrid secant equation 被引量:7
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作者 BABAIE-KAFAKI Saman 《Science China Mathematics》 SCIE 2011年第9期2019-2036,共18页
By making a convex combination of the modified secant equations proposed by Yuan and Wei et al., a hybrid secant equation and also, a modified BFGS algorithm is proposed. The hybridization parameter is effectively com... By making a convex combination of the modified secant equations proposed by Yuan and Wei et al., a hybrid secant equation and also, a modified BFGS algorithm is proposed. The hybridization parameter is effectively computed using the available information of recent iterations. Under proper conditions, it is shown that the proposed algorithm is globally, locally and superlinearly convergent. By using the performance profile introduced by Dolan and Mor6, a comparison between the implementations of the proposed algorithm and two efficient modified BFGS algorithms proposed by Yuan and Wei et al., on a set of unconstrained optimization test problems from the CUTEr collection, is done. Numerical results demonstrating the efficiency of the proposed modified BFGS algorithm are reported. 展开更多
关键词 unconstrained optimization hybrid secant equation BFGS update global convergence local andsuperlinear convergence
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Sufficient Conditions for Heegaard Splittings with Disjoint Curve Property
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作者 尹逊波 雷逢春 《Journal of Mathematical Research and Exposition》 CSCD 北大核心 2008年第2期435-438,共4页
In the paper,we give two conditions that the Heegaard splitting admits the disjoint curve property.The main result is that for a genus g(g■2)strongly irreducible Heegaard splitting(C_1,C_2;F),let D_i be an essential ... In the paper,we give two conditions that the Heegaard splitting admits the disjoint curve property.The main result is that for a genus g(g■2)strongly irreducible Heegaard splitting(C_1,C_2;F),let D_i be an essential disk in C_i,i=1,2,satisfying(1)at least one of ■D_1 and ■D_2 is separating in F and|■D_1∩■D_2|■2g-1;or(2)both ■D_1 and ■D_2 are non-separating in F and|■D_1∩■D_2|■2g-2,then(C_1,C_2;F)has the disjoint curve property. 展开更多
关键词 Heegaard splitting disjoint curve property
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