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Assuming linear theory, the two-dimensional problem of water wave scattering by a horizontal nearly circular cylinder submerged in infinitely deep water with an ice cover modeled as a thin-elastic plat... 相似文献
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Stephen D. Boyles 《Transportation Research Part B: Methodological》2012,46(1):139-155
Subnetwork analysis is often used in traffic assignment problems to reduce the size of the network being analyzed, with a corresponding decrease in computation time. This is particularly important in network design, second-best pricing, or other bilevel problems in which many equilibrium runs must be solved as a subproblem to a master optimization program. A fixed trip table based on an equilibrium path flow solution is often used, but this ignores important attraction and diversion effects as drivers (globally) change routes in response to (local) subnetwork changes. This paper presents an approach for replacing a regional network with a smaller one, containing all of the subnetwork, and zones. Artificial arcs are created to represent “all paths” between each origin and subnetwork boundary node, under the assumption that the set of equilibrium routes does not change. The primary contribution of the paper is a procedure for estimating a cost function on these artificial arcs, using derivatives of the equilibrium travel times between the end nodes to create a Taylor series. A bush-based representation allows rapid calculation of these derivatives. Two methods for calculating these derivatives are presented, one based on network transformations and resembling techniques used in the analysis of resistive circuits, and another based on iterated solution of a nested set of linear equations. These methods are applied to two networks, one small and artificial, and the other a regional network representing the Austin, Texas metropolitan area. These demonstrations show substantial improvement in accuracy as compared to using a fixed table, and demonstrate the efficiency of the proposed approach. 相似文献
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静态爆破法在深圳地铁施工中的应用 总被引:1,自引:0,他引:1
静态爆破是近年来发展起来的一种新型爆破施工技术,它可在无震动、无飞石,无噪音、无污染的条件下破碎或切割岩石或混凝土构筑物。深圳地铁2号线东延线土建工程安托山站—侨香站区间矿山法施工竖井系选用此工法在2 500 mm×3 000 mm雨水箱涵附近成功地进行了中、微风化花岗岩开挖施工,确保了雨水箱涵的安全性。 相似文献
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基于悬索桥在恒载作用下的受力特点,建立了主缆线形控制计算的解析迭代方法,以此确定主缆无应力长度、成桥线形、空缆线形。算例结果表明该解析法具有适合程序计算、收敛速度快、计算精度高的特点,可用于悬索桥设计与施工控制计算。 相似文献
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《铁道标准设计通讯》2016,(9)
怀邵衡铁路沅江特大桥主桥为矮塔斜拉加劲连续梁组合结构,跨径为(90+180+90)m,采用塔、梁固结体系,综述该桥上部结构设计与计算。主梁采用单箱单室变截面混凝土箱梁;桥塔采用双柱式桥塔,塔高28 m;斜拉索为空间双索面体系,扇形布置。采用MIDAS Civil2006及BDAP程序对该桥进行结构计算分析,结果表明:该桥静力、稳定及动力特性均满足要求。 相似文献
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Yutaka Masuyama Yusuke Tahara Toichi Fukasawa Naotoshi Maeda 《Journal of Marine Science and Technology》2009,14(2):137-160
A database of full-scale three-dimensional sail shapes is presented with the aerodynamic coefficients for the upwind condition
of International Measurement System (IMS) type sails. Three-dimensional shape data are used for the input of numerical calculations
and the results are compared with the measured sail performance. The sail shapes and performance were measured using sail
dynamometer boat Fujin. This is a boat of 10.3-m length overall in which load cells and CCD cameras were installed to simultaneously measure the
sail forces and shapes. At the same time, the sailing conditions of the boat, e.g., boat speed, heel angle, wind speed, and
wind angle, were measured. The sail configurations tested were: mainsail with 130% jib, mainsail with 75% jib, and mainsail
alone. Sail shapes were measured at several vertical positions for the shape parameters defined by: chord length, maximum
draft, maximum draft position, entry angle at the luff, and exit angle at the leech, all of which finally yield three-dimensional
coordinates of the sail geometry. The tabulated shape data, along with aerodynamic coefficients, are presented in this article.
In addition, numerical flow simulations were performed for the measured sail shapes and the sailing conditions to investigate
the capability and limitations of the methods through detailed comparison with the measurements. Two numerical methods were
used: a vortex lattice method (VLM) and a Reynolds-averaged Navier–Stokes (RANS)-based computational fluid dynamics method.
The sail shape database, in association with the numerical results, provides a good benchmark for the sail performance analysis
of the upwind condition of IMS type sails. 相似文献