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871.
872.
Rectangular tiles can be laid on a ship’s hull for protection, but the sides of the tiles must be adjusted so adjacent tiles
will conform to the curvature of the hull. A method for laying tiles along a reference line was proposed, and an allowable
range of displacement for the four vertices of the tile was determined. Deformations of each tile on a specific reference
line were then obtained. It was found that the least deformation was required when the tiles were laid parallel to a line
with the least curvature. After calculating the mean curvature on the surface, the surface was divided into three layout areas.
A set of discrete points following the least deformation of the principal curvatures was obtained. A NURBS interpolation curve
was then plotted as the reference line for laying tiles. The optimum size of the tiles was obtained, given the allowable maximum
deformation condition. This minimized the number of bolts and the amount of stuffing. A typical aft hull section was selected
and divided into three layout areas based on the distribution of curvature. The optimum sizes of rectangular tiles were obtained
for every layout area and they were then laid on the surface. In this way the layout of the rectangular tiles could be plotted. 相似文献
873.
While much of the scholarly literature on immigrants’ travel focuses on transit use, the newest arrivals to the United States
make over twelve times as many trips by carpool as by transit. Using the 2001 National Household Travel Survey and multinomial
logit mode choice models, we examine the determinants of carpooling. In particular, we focus on the likelihood of carpooling
among immigrants—carpooling both within and across households. After controlling for relevant determinants of carpooling,
we find that immigrants are far more likely to form household carpools than native-born adults and also are more likely than
the native-born to form external carpools (outside the household). Moreover, when faced with the options of carpooling and
public transit, immigrants—even recent arrivals—appear to prefer carpools over transit more strongly than the native born. 相似文献
874.
Based on nonlinear trajectory generation (NTG) software package, a general approach (i.e. numerical solution) to trajectory
planning for yoyo motion is presented. For the real-time control of such periodical dynamic system, a critical problem is
how to implement fast solving the optimal trajectory, so as to meet the real-time demand. However, traditional numerical solution
methods are very time-consuming. In this paper, the optimization problem is solved by mapping the problem to a lower-dimension
space. And combined with multithread programming technology, the computation time for solving the optimal trajectory is greatly
reduced. Simulation results show that the numerical solution is identical to the analytic one, which demonstrates the correctness
of the proposed method. The computation time of one cycle of yoyo simulation is about 10 ms, which shows that the proposed
numerical method can be applied to the real-time control of yoyo playing. 相似文献
875.
Comprised by a swarm of acoustically linked and cooperative autonomous underwater vehicles (AUVs) with onboard sensors, an
underwater mobile sensing network (UMSN) will be a complementary means to fixed observatory networks, e.g. seafloor observatory
networks and moored buoy arrays. It has obvious advantages over a single large AUV in higher efficiency due to parallel observation,
stronger robustness to vehicle failures and lower cost. Although an UMSN can be viewed as a counterpart of wireless mobile
sensing networks for air and terrestrial applications, it is much more challenging due to poor performance of underwater acoustic
communication, poor performance of underwater positioning and high degree of uncertainty in vehicle dynamics and underwater
environment. In order to verify key technologies involved in an UMSN, e.g. cooperation of multi-AUVs based on acoustic communication,
a low cost testbed has been developed for experimental study. The design of both hardware and software is introduced. Also
the results of a functional test for verification of the effectiveness of the testbed are presented. 相似文献
876.
Abstract This article argues that using the public sector and the private market in the historically delineated and traditional ways offers only the bluntest of tools with which to approach the complex problem of coastal zone management. It therefore seeks to provide a basis for reformulating our understanding of sectoral responsibility with regard to resources management. First, it conceptually analyzes the relative strengths and weaknesses of the two sectors. Second, it examines three examples of coastal resources management—beaches and shorelands, artificial reefs, and coastal wetlands—in analyzing the complexities of the coastal management challenge and the limitations of our current approaches. Finally, we provide an alternative perspective on how these common property resource allocation decisions can be made. 相似文献
877.
从地铁车站建筑的特性出发,结合目前国内地铁车站建筑现状,分析车站建筑形态的自明性表现,总结分析营造车站建筑的差异性的三种典型处理手法,探讨以可持续设计观念来实现车站建筑技术与人文精神的结合。 相似文献
878.
A combination of methods was developed that can determine hydrodynamic forces on a planing hull in steady motion. Firstly, a potential-based boundary-element method was used to calculate the hydrodynamic pressure, induced resistance and lift. Then the frictional resistance component was determined by the viscous boundary layer theory. Finally, a particular empirical technique was applied, to determine the region of upwash geometry and determine spray resistance. Case studies involving four models of Series 62 planing craft were run. These showed that the suggested method is efficient and capable, with results that are in good agreement with experimental measurements over a wide range of volumetric Froude numbers. 相似文献
879.
针对福州火车站高架候车室工程运营过渡和施工组织技术特点,介绍了在边运营边过渡环境条件下,突出优化运营过渡、设计和施工组织所采取的技术措施以及所取得的成效,为同类工程运营过渡和施工组织提供可借鉴的关键技术. 相似文献
880.
随着克拉玛依经济飞速发展,交通量日趋加大,道路面临的压力越来越大,交通的迅猛发展对路面材料的性能提出了更高的要求。沥青玛蹄脂碎石混合料(StoneMatrixAsphalt,缩写为SMA)是近年来在国际上出现的一种非常引人注目的新型沥青混合料,从SMA混合料配合比设计的角度论述了如何确保SMA优异路面使用性能的发挥。 相似文献