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281.
Kazuhiro Iijima Kazuhiro Kimura Weijun Xu Masahiko Fujikubo 《Journal of Marine Science and Technology》2011,16(4):379-389
Dynamic collapse behavior of a ship’s hull girder in waves is investigated; post-ultimate strength behavior is the focus.
Firstly, a simulation method is proposed. Assuming that a plastic hinge is formed during the collapse of the hull girder,
the whole ship is modeled as two rigid bodies connected amidship via a nonlinear rotational spring. The post-ultimate strength
behavior, such as the reduction of load carrying capacity due to buckling and yielding, is reflected in the model. Hydrodynamic
loads are evaluated by using nonlinear strip theory to account for the effect of large plastic deformations on the loads.
A scaled model for validation of the simulation is designed and fabricated. Then a series of tank tests is conducted using
the scaled model to validate the simulation results. Post-ultimate strength behavior characteristics in waves are clarified
by using the numerical and tank test results. It is shown that the hull girder collapses rapidly after reaching ultimate strength,
and then the plastic deformation grows until unloading starts at the collapsed section. Finally, several parametric dependencies
of the extent of the collapse behavior are discussed based on a series of the simulations. 相似文献
282.
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284.
物联网被称为继计算机、互联网之后世界信息产业的第三次浪潮。[1]2009年温家宝总理基于物联网技术发展提出"感知中国"理念并将其上升为国家战略,美国总统奥巴马也把IBM基于物联网技术提出的"智慧地球"理念上升为国家战略。由此可见,当前许多国家都把发展新兴产业的突破口聚焦 相似文献
285.
介绍了柴油机电控单体泵高速电磁阀工作原理及其特点,基于Matlab Simulink对其驱动控制方式进行了仿真分析,给出了单体泵高速电磁阀控制的关键技术。结合分析结果通过对其驱动电路进行了设计,实现了单体泵电磁阀的快速开启与截止,从而精确控制喷油量。 相似文献
286.
This paper presents a numerical analysis of the dynamic transient behaviors of undersea cables. In this numerical study, the
governing equations based on Euler-Bernoulli beam theory are adopted, and they can satisfy many applications no matter what
the magnitude of the cable tension is. The nonlinear coupled equations are solved by a popular central finite difference method,
and the numerical results of transient behaviors are presented when several kinds of surrounding conditions, such as different
towing speeds of surface vessel, different currents and waves with various frequencies and amplitudes, are exerted. Then a
detailed comparison of the results, including the upper end tension and cable shape in time-domain, is made under the above
external excitations, and finally the possible reasons for these are further explained. 相似文献
287.
Interfacial heat transfer is a key issue in many solidification processes. In the paper, a novel experimental apparatus has
been designed and on this basis, the instantaneous interfacial heat transfer between molten steel or solidified shell and
copper substrate during the first 0.2 s has been studied. The investigated parameters include melt superheat, substrate temperature
and surface roughness. The results show that the peak value of the interfacial heat flux in the first stage of liquid/solid
contact increases with melt superheat and changes slightly with substrate temperature and surface roughness. The interfacial
heat flux in the stage of solid/solid contact has a similar trend of slow decrease in most conditions. 相似文献
288.
The numerous construction projects in China provide the best environment for the development of information technology applied
in building design. Various commercial CAD/CAE software applications are purchased by design firms for multi-disciplinary
design tasks. However, researches on integration and interoperability are seldom considered. This study pursues a breakthrough
point of integration in the architectural and structural domains and expects further development in other aspects. A central
building information modeling (BIM) framework based on the industry foundation classes (IFC) is proposed to handle the data
exchange between IFC-compatible architectural models and structural models. A central XML(extensible markup language)-based
unified finite element model (FEM) is proposed for model conversion among various commercial structural CAE software applications.
In addition to bidirectional data interfaces among IFC-based BIM, XML-based FEM and various commercial FEMs, some other components
such as visualization, calculation and model editing/check are also equipped into the prototype system. 相似文献
289.
It has been a focus of debate for a large time on construction methods for large-span loess tunnel. Reasonable construction
method has much effect on stability of tunnel and construction schedule. Deformation and failure of surrounding rock are quite
complex. Associating with the large-span loess tunnel of Zhengzhou—Xi’an high-speed passenger rail line in China, large scale
model test with geometric proportion 1:20 is applied to study on dynamic mechanical behavior of various construction methods.
They include full-face excavation with support and no support, and benching method with support. It is found that pre-deformation
and stress accumulation take place ahead of working face. The effects of three construction methods are further studied, particularly
in terms of tunnel displacement and stress changes. It is revealed that benching method transfers load to an unexcavated area,
limits horizontal deformation, reduces stress concentration effectively, lengthens the distance between location of peak for
stress concentration and working face, and consequently increases stability. The model test results not only supply theoretical
foundation for determination of reasonable construction method, but also can act as reference for similar tunnel and underground
engineering construction. 相似文献
290.
In the field of 3D model matching and retrieval, an effective method for feature extraction is spherical harmonic or its mutations,
and is acted on the spherical images. But the obtainment of spherical images from 3D models is very time-consuming, which
greatly restrains the responding speed of such systems. In this paper, we propose a quantitative evaluation of the whole process
and give a detailed two-sided analysis based on the comparative size between pixels and voxels. The experiments show that
the resultant optimized parameters are fit for the practical application and exhibit a satisfactory performance. 相似文献