侧推孔球状气泡逸出轨迹及振动初探(英文)

In an atrocious ocean environment,the lateral propulsion hole could potentially be partly out of water and capture an air cavity.Bubbles would form when the captured air cavity escapes underwater and they may affect the performance of the sonar.The common commercial computational fluid dynamics software CFX was adopted to calculate the ambient flow field around the lateral propulsion hole generated by a moving vessel.The oscillation of the spherical bubble was based on the Rayleigh-Plesset equation and its migration was modeled using the momentum equation.The radiated noise of the oscillating bubble was also studied.The aim is that the results from this paper would provide some insight into corresponding fluid and acoustic study.     

多管齐下破解堵航难题

近年来，京杭运河、长湖申线等主干航道出现了大范围、持续性的堵航。据不完全统计，2002年至2004年，长湖申线湖州至江苏平望航段共发生大小堵航百余次，其中2002年堵航20次、累计1440小时，疏导受堵船舶18万艘次。2003年堵航31次、累计2232小时，疏导受堵船舶27.9万艘次；2004年实施交通管制122天、累计3000多小时，疏导受堵船舶29万艘次。     

等截面抛物线拱桥内力实用解析解研究

鉴于抛物线拱解析解研究不充分的现状,提出使用近似弧长微分表达式替代精确弧长微分,得出曲线积分的显式表达式,简化了抛物线拱桥内力解析解表达式.基于此方法,对抛物线两铰拱、无铰拱在主拱圈自重、桥面均布荷载作用下的内力实用表达式进行了推导,用常变位数值比较和具体工程实例结果证明了本文方法比常规解析解有更好的精度,比有限元法数...     

Pulsed eddy current signal denoising based on singular value decomposition

The noise as an undesired phenomenon often appears in the pulsed eddy current testing (PECT) signal, and it is difficult to recognize the character of the testing signal. One of the most common noises presented in the PECT signal is the Gaussian noise, since it is caused by the testing environment. A new denoising approach based on singular value decomposition (SVD) is proposed in this paper to reduce the Gaussian noise of PECT signal. The approach first discusses the relationship between signal to noise ratio (SNR) and negentropy of PECT signal. Then the Hankel matrix of PECT signal is constructed for noise reduction, and the matrix is divided into noise subspace and signal subspace by a singular valve threshold. Based on the theory of negentropy, the optimal matrix dimension and threshold are chosen to improve the performance of denoising. The denoised signal Hankel matrix is reconstructed by the singular values of signal subspace, and the denoised signal is finally extracted from this matrix. Experiment is performed to verify the feasibility of the proposed approach, and the results indicate that the proposed approach can reduce the Gaussian noise of PECT signal more effectively compared with other existing approaches.     

世纪大桥平行钢丝斜拉索施工

本文结合世纪大桥平行钢丝拉索的构造特点,着重介绍拉索施工的工艺方法。