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Flow-Induced Vibration Fatigue Damage of A Pair of Flexible Cylinders in A Staggered Array

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China Ocean Engineering 2021年第6期35卷 878-890页

作者： xu wan-hai LI Yu-han JIA Kun LAI Jiang State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China Nuclear Power Institute of China Chengdu 610041China

Flow-induced vibration(FIV)of a group of long,flexible cylinders involves a complex interaction between fluid and *** a substantial number of studies have been devoted to assessing FIV response behaviours,fatigue damage features of staggered flexible cylinders are not fully ***,the wake-induced flutter constitutes an intricate hydrodynamic behaviour that frequently occurs when one cylinder is in the vicinity of another ***,existing studies on the fatigue damage caused by wake-induced flutter are incapable of achieving better *** paper,therefore,estimates the FIV fatigue damage of two staggered flexible cylinders with an aspect ratio of 350 and a mass ratio of 1.90 based on normal S−N curves according to Det Norske Veritas(DNV)*** staggered cases(cross-flow spacing ratios of 2.0,3.0,4.0,and 6.0 and in-line spacing ratios of 4.0,6.0,and 8.0)are discussed for comparison,and fatigue damage caused by wake-induced flutter is thoroughly *** damage results indicate that the variation of the cross-flow(CF)spacing ratio has a greater influence than that of the in-line(IL)spacing ratio on the CF fatigue damage of the upstream *** IL fatigue damages of the upstream cylinder are observed when reduced velocity V_(r)≥15.03 due to the wake flow patterns with different IL spacing ***,wake interference,especially wake-induced flutter,predominates the fatigue damage characteristics of the downstream *** V_(r)=8.77−11.27,wake-induced flutter enhances the IL fatigue damage of the downstream cylinder and slightly affects that of the upstream ***,wake-induced flutter causes considerable IL fatigue damage disparity between the two staggered cylinders by suppressing the IL fatigue damage of the upstream cylinder when V_(r)≥20.04.

关键词： flow-induced vibration fatigue damage flexible cylinder staggered arrangement wake-induced flutter

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军工电子行业的工装管理体系优化

电子质量 2022年第6期 125-127页

作者：杨白丁万海旭何志义中国电子科技集团公司第二十九研究所四川成都610036

传统的军工电子行业科研生产管理中,工装依附于不同的项目进行管理,容易造成工装成本的浪费,数量不精确影响生产计划等问题。该文从规范工装设计数据、优化工装投产策略、规范工装账实管理及加强工装成本核算等维度提出了工装全生命周... 详细信息

传统的军工电子行业科研生产管理中,工装依附于不同的项目进行管理,容易造成工装成本的浪费,数量不精确影响生产计划等问题。该文从规范工装设计数据、优化工装投产策略、规范工装账实管理及加强工装成本核算等维度提出了工装全生命周期管理的整体解决方案。通过本方案的落地实施,在保障军工装备生产计划顺利完成的同时,大幅节约了工装投产成本,有力推动了军工电子行业科研生产管理精益化程度提升。

关键词：工装全生命周期管理成本计划

Study on Pure IL VIV of A Free Spanning Pipeline Under General Boundary Conditions

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China Ocean Engineering 2017年第1期31卷 114-122页

作者： xu wan-hai xu Jing-yu WU Ying-xiang JI Chun-ning State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin University Tianjin 300072 China Collabomtive Innovation Centre for Advanced Ship and Deep-Sea Exploration Shanghai 200240 China Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China

Pipeline spans may occur due to natural seabed irregularities or local scour of bed sediment. The pure in-line（IL）vortex-induced vibrations（VIV） analysis of the free spans is an important subject for design of pipeline in uneven seabed. The main objective of this paper is to analyze the characteristics of pure IL VIV of a free spanning pipeline under general boundary conditions. An IL wake oscillator model which can describe the coupling of pipeline structure and fluctuating drag is introduced and employed. The coupled partial differential equations of structure and wake are transformed into a set of ordinary differential equations using two-mode Galerkin method. Some case studies are presented and thoroughly discussed in order to investigate the effects of internal fluid, axial force and boundary conditions on the pure IL VIV.

关键词： pipeline oscillator spans Pipeline spanning transformed fluctuating details offshore ordinary

雌激素调控瞬时外向钾通道对大鼠慢性颞叶癫发作的影响

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中国临床神经科学 2017年第3期25卷 259-265页

作者：张昱雯黄逸安任婉婷徐海王云汪昕复旦大学附属中山医院神经内科 200032 复旦大学脑科学研究院 200032

目的探讨雌激素对大鼠慢性颞叶癫发作的影响及其与瞬时外向钾通道(kv4.2)之间的关系。方法 SD雌性大鼠随机分为正常对照组、去势对照组、正常致组、去势致组。应用毛果芸香碱诱导大鼠癫持续状态(SE),观察大鼠行为学变化。经4周后成... 详细信息

目的探讨雌激素对大鼠慢性颞叶癫发作的影响及其与瞬时外向钾通道(kv4.2)之间的关系。方法 SD雌性大鼠随机分为正常对照组、去势对照组、正常致组、去势致组。应用毛果芸香碱诱导大鼠癫持续状态(SE),观察大鼠行为学变化。经4周后成为慢性颞叶癫大鼠。Western bolt方法检测大鼠海马瞬时外向钾通道Kv4.2蛋白表达水平。结果与正常致组比较,去势致组达到SE的潜伏期延长、死亡率降低,但差异无统计学意义(P>0.05);去势致组的癫发作强度较正常致组轻,差异有统计学意义(P<0.05)。去势致组和正常致组在SE 4周后海马Kv4.2均较正常对照组显著升高,均差异有统计学意义(P<0.05和P<0.01)。去势对照组和去势致组比较,均未见对Kv4.2蛋白表达产生影响,说明Kv4.2蛋白表达升高为癫发作所致。结论大鼠癫发作后Kv4.2表达增加、瞬时外向钾电流增强、神经冲动的发放频率减慢,可能是产生代偿性自我保护反应的结果;虽然去势雌性大鼠未对Kv4.2表达产生影响,但出现潜伏期延长和死亡率降低、发作强度降低的行为学趋势,提示低剂量雌激素可能存在对癫发作的保护作用。

关键词：雌激素癫 癫持续状态瞬时外向钾通道

Functional response, host stage preference and interference of two whitefly parasitoids

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Insect Science 2016年第1期23卷 134-144页

作者： hai-Yun xu Nian-wan Yang Min Duan Fang-Hao wan State Key Laboratory for Biology of Plant Diseases and Insect Pests Institute of Plant Protection Chinese Academy of Agricultural Sciences Beijing Agricultural Genome Institute at Shenzhen Chinese Academy of Agricultural Sciences Shenzhen Qingdao Agricultural University Qingdao Shandong Province China

The functional responses of two parasitoids, Eretmocerus hayati Zolnerowich ＆ Rose and Encarsia sophia Girault ＆ Dodd, of whitefly Bemisia tabaci Gennadius Middle East-Asia Minor 1 were studied under laboratory conditions. In addition, the influence of host density and host stage on the competitive interactions between the two parasitoids, and biological control effect on whitefly were evaluated. In the functional response study, adult parasitoids were tested individually, with a conspecific or heterospecific competitor. Both Er. hayati and En. sophia exhibited a type II response to increasing host density, whether a conspecific or heterospecific competitor was present or not. Difference of searching rates and handling times between treatments suggested interference interactions existed between two parasitoid species. In the host stage preference study, two parasitoid species were jointly tested. Er. hayati had a competitive advantage over En. sophia when provided young host instars （first and second instar）, whereas no advantage was found on old host instars （third and fourth instar）. The biological control effect ofEr hayati and En. sophia in different introductions varied with host density. However, the effect of host instar on host mortality was not significant. These findings provide information for the practice of biological control and give better insight into how parasitoid species may coexist in diverse environments.

关键词： Bemisia tabaci Encarsia sophia Eretmocerus hayati functional response interspecific competition

Vortex-Induced Vibration Response Features of A Submarine Multi-Span Pipeline via Towing Tank Experimental Tests

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China Ocean Engineering 2023年第2期37卷 175-189页

作者： xu wan-hai JIA Kun MA Ye-xuan SONG Zhi-you State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China

In offshore engineering, the phenomenon of free span often occurs, and the pipeline may have multiple free spans adjacent to each other, forming a multi-span pipeline. The interaction of different spans makes the structural vibration characteristics more complex, which may change the fatigue characteristics of the pipeline and affect the safety of the structure. In this paper, model tests were designed to explore the vortex-induced vibration(VIV) characteristics of multi-span pipelines and investigate the multi-span interaction mechanism. The experimental study mainly focused on the dynamic response of double-span pipelines, and further extended to triple-span pipelines, hoping that the results can be applied to more complex environment. The effects of span-length ratio, buried depth and axial force on VIV of the pipeline were investigated and discussed. The dynamic response of the pipeline varied with the span length. There was obvious interaction between different spans of multi-span pipelines, and the pipe-sediment interaction obviously affected the vibration characteristics of pipeline. The differences of pipeline burial depth and axial force changed the structural stiffness. With the increase of buried depth, the response amplitude presented a downward trend. The spanwise evolutions were asymmetric caused by the pipe-sediment interaction and multi-span interaction. The results can help to identify multi-span pipelines in engineering, and realize the prevention and control of free spans.

关键词： vortex-induced vibration submarine pipeline pipe-sediment interaction multi-span interaction

Passive VIV Reduction of An Inclined Flexible Cylinder by Means of Helical Strakes with Round-Section

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China Ocean Engineering 2018年第4期32卷 413-421页

作者： xu wan-hai QIN Wen-qi HE Ming GAO Xi-feng State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin University

A series of experimental tests of passive VIV suppression of an inclined flexible cylinder with round-sectioned helical strakes were carried out in a towing tank. During the tests, the cylinder models fitted with and without helical strakes were towed along the tank. The towing velocity ranged from 0.05 to 1.0 m/s with an interval of 0.05 m/*** different yaw angles(a=0°, 15°, 30° and 45°), defined as the angle between the axis of the cylinder and the plane orthogonal of the oncoming flow, were selected in the experiment. The main purpose of present experimental work is to further investigate the VIV suppression effectiveness of round-sectioned helical strakes on the inclined flexible cylinder. The VIV responses of the smooth cylinder and the cylinder with square-sectioned strakes under the same experimental condition were also presented for comparison. The experimental results indicated that the roundsectioned strake basically had a similar effect on VIV suppression compared with the square-sectioned one, and both can significantly reduce the VIV of the vertical cylinder which corresponded to the case of a=0°. But with the increase of yaw angle, the VIV suppression effectiveness of both round-and square-section strakes deteriorated dramatically, the staked cylinder even had a much stronger vibration than the smooth one did in the in-line(IL)direction.

关键词： VIV suppression Helical strakes inclined flexible cylinder yaw angle round-section

Response of Two Unequal-Diameter Flexible Cylinders in A Side-by-Side Arrangement:Characteristics of FIV

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China Ocean Engineering 2020年第4期34卷 475-487页

作者： xu wan-hai ZHANG Qian-nan MA Wen-chen wanG En-hao State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China Department of Civil and Environmental Engineering and Construction University of NevadaNV 89154USA

Till now,little information is available on the flow-induced vibration(FIV)of multiple flexible cylinders with unequal *** FIV characteristics of unequal-diameter cylinders can be predicted based on the knowledge of equal-diameter cylinders,while there are still other features remaining *** this paper,the FIV characteristics of two flexible cylinders with unequal diameters arranged side-by-side are experimentally *** diameter ratio of the small cylinder(Small Cyl.)to the large cylinder(Large Cyl.)is nearly *** aspect ratios and mass ratios of the two flexible cylinders are 350/181 and 1.90/1.47,*** centre-tocentre spacing ratio in the cross-flow(CF)direction is kept constant as 6.0 and the two cylinders can oscillate freely in both the CF and in-line(IL)*** towing velocity varies from 0.05 m/s to 1.00 m/*** dominant modes and frequencies,CF and IL displacement amplitudes and response trajectories are *** with the case of two identical cylinders in our previous study,the FIV responses demonstrate some similarities and *** similarities are as *** cylinders exhibit multi-mode vibration features and they interact with each ***,the IL FIV shows a more complex behaviour than that in the CF *** difference is that as the diameter of one cylinder is increased,the effect on the smaller cylinder becomes more *** Large Cyl.,the FIV response is similar to its isolated counterpart,which indicates that Small *** a negligible effect on the FIV of the larger *** Large *** the FIV of Small *** the vibration *** spacing would change when both cylinders are *** interference between the two cylinders and wake shielding effect of the Large *** *** dominant frequencies of Small *** reduced and the wake-induced flutter of Small *** observed from the response trajectories at different mea

关键词： flow-induced vibration(FIV) flexible cylinder side-by-side unequal diameter wake-induced flutter

Passive Control of Flow-Induced Vibration(FIV)by Helical Strakes for Two Staggered Flexible Cylinders

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China Ocean Engineering 2021年第4期35卷 475-489页

作者： xu wan-hai wanG Qi-cheng QIN Wen-qi DU Zun-feng State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China School of Civil Engineering Tianjin UniversityTianjin 300072China CIMC Offshore Co.Ltd Shenzhen 518000China

Helical strake is a widely-used device for passive flow-induced vibration(FIV)control of cylindrical *** is omnidirectional and can effectively reduce FIV response *** on the passive FIV control for cylindrical structures are mainly concerned with a single isolated cylinder,while the influence of wake interference between multiple cylinders on FIV suppression devices is less considered up to *** engineering applications,multiple flexible cylinders with large aspect ratios can be subjected to complex flow forces,and the effects of wake interference are *** FIV suppression effect of helical strake of a common configuration(17.5D pitch and 0.25D height,where D is the cylinder diameter)in two staggered cylinders system is still *** paper systematically studied the FIV response of multiple cylinders system fitted with the helical strakes by model *** relative spatial position of the two cylinders is fixed at S=3.0D and T=8.0D,which ensures the cylindrical structures in the flow interference *** experimental results show that the helical strakes effectively reduce the FIV response on staggered upstream cylinder,and the suppression efficiency is barely affected by the smooth or straked downstream *** corresponding FIV suppression efficiency on the downstream cylinder is remarkably reduced by the influence of the upstream wake *** wake-induced vibration(WIV)phenomenon is not observed on the staggered downstream cylinder,which normally occurs on the downstream straked cylinder in a tandem arrangement.

关键词： flow-induced vibration(FIV) passive control helical strakes flexible cylinders staggered arrangement