检索结果-南通市图书馆

Hydrodynamics of A Flexible Riser Undergoing the Vortex-Induced Vibration at High Reynolds Number

China Ocean Engineering 2018年第5期32卷 570-581页

作者： REN Tie ZHANG Meng-meng fu shi-xiao SONG Lei-jian State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Centre for Advanced ship and Deep-Sea Exploration Shanghai 200240China Marine Design&Research Institute of China Shanghai 200011China Shanghai Electric Wind Power Group Shanghai 200030China

This study proposed a method to obtain hydrodynamic forces and coefficients for a flexible riser undergoing the vortex-induced vibration(VIV), based on the measured strains collected from the scale-model testing with the Reynolds numbers ranging from 1.34 E5 to 2.35 E5. The riser is approximated as a tensioned spatial beam, and an inverse method based on the FEM of spatial beam is adopted for the calculation of hydrodynamic forces in the cross flow(CF) and inline(IL) directions. The drag coefficients and vortex-induced force coefficients are obtained through the Fourier Series Theory. Finally, the hydrodynamic characteristics of a flexible riser model undergoing the VIV in a uniform flow are carefully investigated. The results indicate that the VIV amplifies the drag coefficient, and the drag coefficient does not change with time when the CF VIV is stable. Only when the VIVs in the CF and IL directions are all steady vibrations, the vortex-induced force coefficients keep as a constant with time, and under"lock-in" condition, whether the added-mass coefficient changes with time or not, the oscillation frequency of the VIV keeps unchanged. It further shows that the CF excitation coefficients at high frequency are much smaller than those at the dominant frequency, while, the IL excitation coefficients are in the same range. The axial distributions of the excitation and damping region at the dominant frequency and high frequency are approximately consistent in the CF direction, while, in the IL direction, there exists a great difference.

关键词： flexible riser vortex-induced vibration vortex-induced force excitation coefficient added-mass coefficient drag coefficient

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Tension and Drag Forces of Flexible Risers Undergoing Vortex-Induced Vibration

引用

China Ocean Engineering 2017年第1期31卷 1-10页

作者： SONG Lei-jian fu shi-xiao LI Man GAO Yun MA Lei-xin State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center for Advanced ship and Deep-Sea Exploration Shanghai 200240China Marine Design & Research Institute of China Shanghai 200011China State Key Laboratory of Oil and Gas Reservoir Geology and Exploration Southwest Petroleum UniversityChengdu 610500China

This paper presents the results of an experimental investigation on the variation in the tension and the distribution of drag force coefficients along flexible risers under vortex-induced vibration（VIV） in a uniform flow for Reynolds numbers（Re） up to 2.2×10^5. The results show that the mean tension is proportional to the square of the incoming current speed, and the tension coefficient of a flexible riser undergoing VIV can be up to 12. The mean drag force is uniformly and symmetrically distributed along the axes of the risers undergoing VIV. The corresponding drag coefficient can vary between 1.6 and 2.4 but is not a constant value of 1.2, as it is for a fixed cylinder in the absence of VIV. These experimental results are used to develop a new empirical prediction model to estimate the drag force coefficient for flexible risers undergoing VIV for Reynolds number on the order of 10^5, which accounts for the effects of the incoming current speed, the VIV dominant modal number and the frequency.

关键词： Reynolds riser cylinder vortex Vortex hydrodynamic empirical turbulent averaged oscillating

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Hydrodynamics of the Semi-Immersed Cylinder by Forced Oscillation Model Testing

引用

China Ocean Engineering 2018年第1期32卷 110-116页

作者： SONG Chun-hui fu shi-xiao TANG xiao-ying HU Ke MA Lei-xin REN Tong-xin State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center for Advanced shipand Deep-Sea Exploration Shanghai 200240China School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China Tianjin Research Institute for Water Transport Engineering Tianjin 300000China Massachusetts Institute of Technology CambridgeMA 02139USA

In this paper, the hydrodynamic coefficients of a horizontal semi-immersed cylinder in steady current and oscillatory flow combining with constant current are obtained via forced oscillation experiments in a towing tank. Three nondimensional parameters(Re, KC and Fr) are introduced to investigate their effects on the hydrodynamic *** experimental results show that overtopping is evident and dominates when the Reynolds number exceeds 5×105 in the experiment. Under steady current condition, overtopping increases the drag coefficient significantly at high Reynolds numbers. Under oscillatory flow with constant current condition, the added mass coefficient can even reach a maximum value about 3.5 due to overtopping while the influence of overtopping on the drag coefficient is minor.

关键词： semi-immersed cylinder hydrodynamic coefficient forced oscillation experiment overtopping

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

An experiment study of vortex induced vibration of a steel catenary riser under steady current

引用

Journal of Hydrodynamics 2020年第5期32卷 834-844页

作者： Tie Ren Yu-wang Xu Jungao Wang Hao-jie Ren Meng-meng Zhang shi-xiao fu Yao-song Chen State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Centre for Advanced ship and Deep-Sea Exploration Shanghai 200240China Marine Design and Research Institute of China Shanghai 200011China Norweigian Public Road Administration StavangerNorway

The vortex induced vibration(VIV)of marine risers has been investigated by many researchers in experimental studies of a straight flexible riser model as well as a rigid cylinder to reveal the dynamic response characteristic and the mechanics behind ***,due to the limitation of experimental apparatus,very few studies are about the VIV of a steel catenary riser(SCR)which is with a complex *** investigate the VTV features and to further develop the corresponding numerical predictions of a SCR under steady current,a large-scale model test of a SCR was towed in an ocean basin at various *** Bragg grating strain sensors are instrumented on the riser model to measure both in-plane and out-of-plane *** characteristics of oscillating amplitude and dominating frequency response,the phenomenon of mode competition and travelling wave and the fatigue damage of the steel catenary riser in inline and cross-flow direction under steady current are analyzed.

关键词： Vortex induced vibration(VTV) steel catenary riser(SCR) experimental study

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Clinicians’prescription preferences for treating patients with Alzheimer’s disease in Shanghai

引用

Translational Neurodegeneration 2016年第1期5卷 67-74页

作者： Chun-Xia Ban shi-fu xiao Xiang Lin Tao Wang Qi Qiu Min-Jie Zhu Xia Li Alzheimer’s Disease and Related Disorders Center Department of Geriatric PsychiatryShanghai Mental Health CenterShanghai Jiao Tong University School of MedicineShanghaiChina Mental Health Center of Jiading District in Shanghai ShanghaiChina

Background:China has more cases of Alzheimer’s disease(AD)than any other country in the *** training to recognize and manage dementia is in its early stage,it is important to study clinicians’current prescription preferences for treating patients with ***:This study surveyed neurologists,psychiatrists,and general physicians(GPs)in Shanghai who had outpatients with AD,using a questionnaire asking about their prescription preferences for these ***:Among the 148 clinicians in the study,26.4%were psychiatrists,44.6%were neurologists,and 29.1%were *** groups did not differ significantly in age,gender,or their monthly cases of new patients with mild or moderate AD(P>0.05).Most clinicians prescribed Cholinesterase inhibitors(ChEIs),including Huperzine A,but there were significant group-differences in prescribing specific ChEIs(P0.05),and all three groups prescribed piracetam,ergot,and ginkgo biloba *** three groups also tended to treat AD patients with a combination of antidepressants and anxiolytics,although psychiatrists were significantly more likely than neurologists to combine antipsychotics with other drugs(P<0.05).Conclusion:Clinicians in Shanghai prescribed low doses of ChEIs and Memantine for patients with AD.A relatively high proportion also prescribed cognitive enhancers,which lack evidence-based support of their use,and *** is a need for more training about treating patients with AD and for clinicians to standardize their clinical practice.

关键词： Alzheimer’s disease Clinicians Cognitive enhancers Prescriptions Survey research

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Cognitive decline is related to high blood glucose levels in older Chinese adults with the ApoE ε3/ε3 genotype

引用

Translational Neurodegeneration 2019年第1期8卷 134-140页

作者： Qi Qiu Xiang Lin Lin Sun Min-jie Zhu Tao Wang Jing-hua Wang Guan-jun Li shi-fu xiao Xia Li Department of Psychogeriatrics Shanghai Mental Health CenterShanghai Jiao Tong University School of MedicineSouth WanPing Road 600Shanghai 200030China

Background:Few studies have investigated the effects of blood glucose(BG)on cognitive function in communitydwelling elderly individuals carrying the apolipoprotein E(APOE)ε3 ***:To explore the effect of high BG levels on cognitive function in APOEε3-carrying,non-demented,community-dwelling older adults,as compared to their counterparts carrying the APOEε4 or APOEε2 ***:Within the China Longitudinal Ageing Study,we recruited 282 elderly adults without *** collected included demographic information;psychological measures;laboratory test results,including BG and plasma lipid levels;and APOE *** divided the participants into APOEε2(ε2/ε2,ε2/ε3),ε3(ε3/ε3),andε4(ε3/ε4,ε4/ε4)*** correlation analyses and multivariate linear regression analyses were utilized to compare the cognitive function and laboratory data between the APOE *** matter hyperintensity(WMH)was measured on magnetic resonance images in 77 ***:With adjustment for age,sex,education,and diabetes,higher BG in non-demented community-dwelling older adults was associated with cognitive decline in immediate memory and executive *** the APOEε3 group,elevated BG was associated with cognitive decline in immediate memory,executive function,and perceptual *** the APOEε4 group,higher BG was also correlated with a decline in abstract *** was a trend for association between higher BG and more severe ***:Worse cognitive function was correlated withApoEε3/ε3 genotype carriers with higher BG in community-dwelling older adults.

关键词： Apolipoproteins E Cognition Blood glucose Aged White matter Community-based

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

不规则波和流下的重力式网箱水弹性响应研究（英文）

引用

船舶力学 2018年第3期22卷 260-275页

作者：胡克付世晓上海交通大学海洋工程国家重点实验室上海200240 高新船舶与深海开发装备协同创新中心上海200240

文章对重力式网箱在不规则波和流作用下的水弹性响应分析进行了研究,通过有限元方法建立实尺度网箱模型并对网箱的运动和变形进行了分析。在数值模型中,通过非线性弹簧单元和Truss单元来模拟锚链和渔网结构,通过若干耦合的梁按照"浮力... 详细信息

文章对重力式网箱在不规则波和流作用下的水弹性响应分析进行了研究,通过有限元方法建立实尺度网箱模型并对网箱的运动和变形进行了分析。在数值模型中,通过非线性弹簧单元和Truss单元来模拟锚链和渔网结构,通过若干耦合的梁按照"浮力分配法"来计算浮圈的瞬时浮力。基于这个计算模型,文中充分研究了当网箱处于波流载荷下,浮圈的各阶弹性体模态所占权重。结果显示,当有义波高增大时,在垂直方向上会激发出更多的浮圈弹性体模态,而流则主要影响水平方向上的刚体模态。

关键词：重力式网箱有限元分析不规则波和流水弹性响应

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

弹性浮体的二阶平均漂移力研究

引用

船舶力学 2024年第5期28卷 651-662页

作者：李帅付世晓张仕元上海交通大学海洋工程国家重点实验室上海200240 高新船舶与深海开发装备协同创新中心上海200240

本文基于离散模块思想,提出一种求解弹性浮体二阶平均漂移力的数值方法。首先将连续弹性浮体离散为弹性梁连接的刚性模块系统,实现弹性梁刚度和各模块水动力信息的耦合,在频域内求解浮体一阶水弹性响应。然后利用二阶多体水动力理论,并... 详细信息

本文基于离散模块思想,提出一种求解弹性浮体二阶平均漂移力的数值方法。首先将连续弹性浮体离散为弹性梁连接的刚性模块系统,实现弹性梁刚度和各模块水动力信息的耦合,在频域内求解浮体一阶水弹性响应。然后利用二阶多体水动力理论,并考虑计及结构弹性变形影响后的各模块一阶运动信息,获得各刚性模块上的二阶平均漂移力。最后,利用该方法求解自由柔性驳船的平均漂移力,并与基于模态叠加思想的三维水弹性理论的计算结果进行对比验证。此外,由于本文方法在水动力求解方面的离散特性,该方法可直接拓展到非均匀波浪场下浮体的水弹性响应分析。

关键词：水弹性离散模块平均漂移力频域

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

海上风力发电机组支撑结构动力特性分析

引用

振动与冲击 2012年第2期31卷 86-90页

作者：陈前付世晓邹早建上海交通大学船舶海洋与建筑工程学院上海200240 上海交通大学海洋工程国家重点实验室上海200240

采用欧拉-伯努利梁模型来模拟海上风力发电机组的支撑结构,利用通用有限元软件ANSYS对机组支撑结构进行计算建模。在此基础上,分析了风力发电机组上端结构质量(风轮、机舱等)、整个机组重力以及海水对支撑结构固有频率的影响,并给出瞬... 详细信息

采用欧拉-伯努利梁模型来模拟海上风力发电机组的支撑结构,利用通用有限元软件ANSYS对机组支撑结构进行计算建模。在此基础上,分析了风力发电机组上端结构质量(风轮、机舱等)、整个机组重力以及海水对支撑结构固有频率的影响,并给出瞬态冲击下支撑结构的动力响应历程。计算结果表明,在计算海上风力发电机组支撑结构固有频率时应考虑上端结构质量的影响,可以不考虑重力的影响,而海水对高阶固有频率影响很大;在瞬态冲击下,上端结构质量使得支撑结构响应变得平缓。

关键词：海上风力发电机组支撑结构固有频率动力响应

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

基于HHT方法的柔性立管涡激振动特性分析研究

引用

船舶力学 2022年第1期26卷 81-90页

作者：李曼傅何琪朱青淳付世晓中国船舶及海洋工程设计研究所上海200011 上海交通大学海洋工程国家重点实验室上海200240

本文针对试验中的柔性立管涡激振动响应特性问题,使用HHT方法进行分析。首先,将试验中获得的应变时历转化为位移时历,并进行EMD分解,分析确认分解结果的正确性。然后,根据分解结果,统计分析立管涡激振动模态数与流速的关系。之后,使用HH... 详细信息

本文针对试验中的柔性立管涡激振动响应特性问题,使用HHT方法进行分析。首先,将试验中获得的应变时历转化为位移时历,并进行EMD分解,分析确认分解结果的正确性。然后,根据分解结果,统计分析立管涡激振动模态数与流速的关系。之后,使用HHT方法分析立管涡激振动的频率响应特性,获得确认立管振动阶数的方法,在试验中发现“倍频”现象,并总结“倍频”现象分布的流速区间。最终,通过观察立管振动位移的时空分布,获得立管振动的阶数,发现了振型的不对称特性,并分析其导致模态混淆的原因,同时观察到立管振动模态的激励发展过程,并最终总结了不同流速下立管响应模态阶数及对应频率。

关键词：柔性立管涡激振动 HHT方法响应特性

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：