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排序方式: 共有108条查询结果,搜索用时 15 毫秒
81.
本文通过对我公司制动蹄产品双排孔加工步序设备进行调整和更新,极大的提高了该步序的加工能力,由原来的日产1500件提升到日产2500件,减少了机床投入,降低了员工劳动强度,提高了加工效率,为企业创造了可观的经济效益。 相似文献
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以大连开发区小窑湾立交桥为例,从设计概述、主要技术指标及线形设计方面对该立交桥进行论述,并对立交桥线形设计进行总结。 相似文献
84.
A primitive equation ocean model is used to generate trajectories of simulated clusters of drifters in the California Current (CC) region. These trajectories allow us to evaluate a least squares (LS) method of estimating vorticity and vertical velocity along a cluster's path. Two clusters provide examples of successful and less successful estimates of vorticity and vertical velocity. Our analysis quantifies the dependence of estimate quality on several parameters that can be used as error predictors in the LS estimate of vorticity: cluster separation, number of drifters in a cluster, and cluster shape. A combination of cluster separation and ellipticity shows the most promise as an indicator of quality for the vorticity estimate. 相似文献
85.
Jong-Chun Park Moo-Hyun Kim Hideaki Miyata 《Journal of Marine Science and Technology》2001,6(2):70-82
A finite-difference scheme and a marker-and-cell (MAC) method are used for numerical wave tank (NWT) simulations to investigate
the characteristics of nonlinear wave motions and their interactions with a stationary three-dimensional body in the presence
of steady uniform currents. The Navier–Stokes (NS) equation is solved in the computational domain, and the boundary values
are updated at each time-step by a finite-difference time-marching scheme in the frame of a rectangular coordinate system.
The fully nonlinear kinematic free-surface condition is satisfied by the marker–density function technique developed for two
fluid layers. The incident waves are generated from the inflow boundary by prescribing a velocity profile resembling the motions
of a flexible flap wavemaker, and the outgoing waves are numerically dissipated inside an artificial damping zone located
at the end of the tank. Using the NS–MAC NWT, nonlinear wave and current interactions around a stationary vertical truncated
circular cylinder are studied, and the results are compared with the experimental results of Mercier and Niedzwecki, a time-domain
NWT based on linear potential theory, a fully nonlinear NWT, and a second-order diffraction computation.
Received: July 3, 2001 / Accepted: September 25, 2001 相似文献
86.
Wave-induced vertical bending moment (VBM) and horizontal bending moment (HBM) on a large-scale segmented model with a box-type backbone beam in short-crested irregular seas are systematically analyzed using sea trial measurement data. New insights into the relationship between nonlinear VBM and HBM of the ship sailing in short-crested sea waves are explored and presented. The results indicate that the HBM significantly contributes to the total sectional loads when the ship is sailing in a seaway and the HBM has a strong correlation with VBM in both magnitude and tendency. Therefore, design loads of HBM and the corresponding lateral structural strength issues should also be concerned in addition to VBM at the ship design phase. 相似文献
87.
Although the nonlinear effects of the ship motions, wave-induced loads and structural responses of conventional vessels have been investigated experimentally and numerically in recent years, similar studies on the wave-piercing tumblehome (WPTH) vessels are rare, in spite of the urgent necessary due to their extensive applications. This paper experimentally investigated the nonlinear effects of the vertical motions and vertical bending moment (VBM) for a WPTH vessel based on a hydro-elastic segmented model test. The model test was carried out in head regular waves for three amplitudes, in the towing tank at Harbin Engineering University. Based on the band-pass filter technique, four kinds of decomposed harmonics are defined by mean offset, linear wave-frequency response, nonlinear wave-frequency response and nonlinear high-frequency vibration. Meanwhile, based on mean offset, three kinds of combined responses are defined by considering linear wave-frequency response, nonlinear wave-frequency response and nonlinear high-frequency vibrations step by step. The transfer functions of vertical motions and VBM are presented as function of the incident wave frequency, and the measured data and VBM were compared with numerical calculations for validation. With the method proposed above, the results of VBM are analyzed by focusing on the influences of decomposed harmonics on the amplitudes and asymmetry of combined responses. Strong nonlinear effects are observed in the VBM. The nonlinearity of VBM can be identified by the significant amplitudes of decomposed harmonics, variation of amplitude with the wave amplitude and remarkable asymmetry about the zero axis. The hogging VBM of WPTH vessel can be even larger than the sagging VBM, which is in contrast to the general experiences from conventional vessels. Combined the calculated relative motion with the decomposed and combined histories of VBM, the occurrence of the transient impact and its characteristics are discussed, and these are then used to analyze the unconventional asymmetry of VBM. Furthermore, the influences of the bow shape over the vertical motions and VBM are discussed. At the end of the paper, the uncertainties in the test are provided. 相似文献
88.
The vertical axis wind turbine (VAWT) configuration has many advantages for an offshore wind turbine installation. The VAWT is omnidirectional and its rotating mechanical components can be placed close to sea level. In this paper, the structural analysis of a VAWT blade structure subject to a critical load case was investigated with two methods, an analytical model and a finite element (FE) model. It was shown that the utilisation of a composite blade topology can resist the induced flapwise loading and the material strains were contained within their allowable limits. The analytical approach was demonstrated to be a quick and accurate technique to compute the composite blade strain distribution when compared to the FE model results. 相似文献
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采用方格网法将交叉口划分为四边形或三角形网格,将所有网格点作为设计计算点,利用圆心法确定各计算点的初始高程计算线,通过等分法、迭代法对初始高程计算线进行调整,并得到计算点的设计高程,根据网格点平面坐标及高程数据绘制设计等高线及三维表面效果图用于设计调整与质量检验。综合法所得竖向设计表面平顺,计算结果便于直接应用于工程的图纸设计与施工,该方法集成了方格网法、圆心法、等分法及等高线法的优点并加以改进,方法更加完善,工程适用性得到提高。 相似文献