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A novel structural modification to eliminate the early coupling between bending and torsional mode shapes in a cable stayed bridge

Nazim Abdul NARIMAN

《结构与土木工程前沿（英文）》 2017年 第11卷 第2期   页码 131-142 doi: 10.1007/s11709-016-0376-4

摘要： In this paper, a novel structural modification approach has been adopted to eliminate the early coupling between the bending and torsional mode shapes of vibrations for a cable stayed bridge model generated using ABAQUS software. Two lateral steel beams are added to the middle span of the structure. Frequency analysis is dedicated to obtain the natural frequencies of the first eight mode shapes of vibrations before and after the structural modification approach. Numerical simulations of wind excitations are conducted for the 3D model of the cable stayed bridge with duration of 30 s supporting on real data of a strong wind from the literature. Both vertical and torsional displacements are calculated at the mid span of the deck to analyze both the bending and the torsional stiffness of the system before and after the structural modification. The results of the frequency analysis after applying lateral steel beams declared a safer structure against vertical and torsional vibrations and rarely expected flutter wind speed. Furthermore, the coupling between the vertical and torsional mode shapes has been removed to larger natural frequencies magnitudes with a high factor of safety. The novel structural approach manifested great efficiency in increasing vertical and torsional stiffness of the structure.

关键词： aeroelastic instability     structural damping     flutter wind speed     bending stiffness     torsional stiffness    

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Mean wind load induced incompatibility in nonlinear aeroelastic simulations of bridge spans

Zhitian ZHANG

《结构与土木工程前沿（英文）》 2019年 第13卷 第3期   页码 605-617 doi: 10.1007/s11709-018-0499-x

摘要： Mean wind response induced incompatibility and nonlinearity in bridge aerodynamics is discussed, where the mean wind and aeroelastic loads are applied simultaneously in time domain. A kind of incompatibility is found during the simultaneous simulation of the mean wind and aeroelastic loads, which leads to incorrect mean wind structural responses. It is found that the mathematic expectations (or limiting characteristics) of the aeroelastic models are fundamental to this kind of incompatibility. In this paper, two aeroelastic models are presented and discussed, one of indicial-function-denoted (IF-denoted) and another of rational-function-denoted (RF-denoted). It is shown that, in cases of low wind speeds, the IF-denoted model reflects correctly the mean wind load properties, and results in correct mean structural responses; in contrast, the RF-denoted model leads to incorrect mean responses due to its nonphysical mean properties. At very high wind speeds, however, even the IF-denoted model can lead to significant deviation from the correct response due to steady aerodynamic nonlinearity. To solve the incompatibility at high wind speeds, a methodology of subtraction of pseudo-steady effects from the aeroelastic model is put forward in this work. Finally, with the method presented, aeroelastic nonlinearity resulted from the mean wind response is investigated at both moderate and high wind speeds.

关键词： bridge     aerodynamics     nonlinear     aeroelastic model     Pseudo-steady     mean wind loads    

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Combustion instability detection using the wavelet detail of pressure fluctuations

JI Junjie, LUO Yonghao

《能源前沿（英文）》 2008年 第2卷 第1期   页码 116-120 doi: 10.1007/s11708-008-0019-0

摘要： A combustion instability detection method that uses the wavelet detail of combustion pressure fluctuations is put forward. To confirm this method, combustion pressure fluctuations in a stoker boiler are recorded at stable and unstable combustion with a pressure transducer. Daubechies one-order wavelet is chosen to obtain the wavelet details for comparison. It shows that the wavelet approximation indicates the general pressure change in the furnace, and the wavelet detail magnitude is consistent with the intensity of turbulence and combustion noise. The magnitude of the wavelet detail is nearly constant when the combustion is stable, however, it will fluctuate much when the combustion is unstable.

关键词： comparison     wavelet approximation     pressure transducer     general pressure     consistent    

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海底不稳定性研究进展及展望

高伟健,李伟

《中国工程科学》 2023年 第25卷 第3期   页码 109-121 doi: 10.15302/J-SSCAE-2023.03.010

摘要：

海底不稳定性及次生海底地质灾害广泛存在于海洋之中，对海岸港口设施、海洋钻井平台、海底管道光缆等海底基础建设颇具威胁。但目前对海底不稳定性的成因机制与主控因素仍知之甚少，为加深对海底不稳定性的认识，本文回顾了海底不稳定性研究进展，梳理了海底不稳定性及次生海底地质灾害的主要类别、全球分布情况和地球物理识别特征，归纳了目前海底不稳定性研究的定量分析方法，进一步分析了其成因机制、控制因素及工程地质灾害风险，探讨了海底陆坡失稳演化过程试验模拟技术的适用范畴与技术瓶颈。最后，从海底不稳定性的致灾机理研究、多源数据智能分析和海底失稳立体监测3 个维度提出了未来海底不稳定性研究的发展方向与对策建议，以期为海底不稳定性的模拟、预测和预警等工作提供指导性建议。

关键词： 海底不稳定性；海底地质灾害；成因机制；风险评估；不稳定性分析    

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表面张力作用下柱形胶体的弹性失稳

黄殿武,乔玲,汪时机

《中国工程科学》 2007年 第9卷 第4期   页码 50-54

摘要：

采用弹性理论研究了圆柱形胶体在表面张力作用下的弹性失稳问题；利用能量泛函变分的方法导出 了发生弹性失稳的非经典边界条件，得到了失稳的判据方程。分析判据方程发现，弹性失稳与圆柱体的半径、 内禀尺度和失稳波长相关。

关键词： 柱形胶体     弹性失稳     内禀尺度     表面效应    

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工程饱和介质中漩涡光的调制不稳定性 Review

D.G. Pires, N.M. Litchinitser

《工程（英文）》 2022年 第17卷 第10期   页码 31-43 doi: 10.1016/j.eng.2022.04.022

摘要：

光束在水下环境、雾、云或生物组织等混浊介质中的传播在科学和技术中有着越来越重要的应用，包括生物成像、水下和自由空间通信技术。虽然这些应用在传统上依赖于常规的线性偏振高斯光束，但光具有许多未被发掘的自由度，如自旋角动量（SAM）和轨道角动量（OAM）。本文提出了具有“旋转”自由度的复杂光束在工程化非线性胶体介质中的非线性光-物质相互作用。利用变分法和摄动法，我们考虑了非圆柱光学涡旋、椭圆光学涡旋和高阶贝塞尔光束在时间上的积分（HOBBIT），来预测这些光束演化的动力学行为和稳定性。这些结果可应用于许多强散射环境下涉及光透射的情况。

关键词： Optical vortex     Orbital angular momentum     Modulation instability     Turbid media    

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Control of wind-induced vibration of long-span bridges and tall buildings

GU Ming

《结构与土木工程前沿（英文）》 2007年 第1卷 第1期   页码 51-62 doi: 10.1007/s11709-007-0005-3

摘要： With the rapid increase in scales of structures, research on controlling wind-induced vibration of large-scale structures, such as long-span bridges and super-tall buildings, has been an issue of great concern. For wind-induced vibration of large-scale structures, vibration frequencies and damping modes vary with wind speed. Passive, semiactive, and active control strategies are developed to improve the wind-resistance performance of the structures in this paper. The multiple tuned mass damper (MTMD) system is applied to control vertical bending buffeting response. A new semiactive lever-type tuned mass damper (TMD) with an adjustable frequency is proposed to control vertical bending buffeting and torsional buffeting and flutter in the whole velocity range of bridge decks. A control strategy named sinusoidal reference strategy is developed for adaptive control of wind-induced vibration of super-tall buildings. Multiple degrees of freedom general building aeroelastic model with a square cross-section is tested in a wind tunnel. The results demonstrate that the proposed strategies can reduce vibration effectively, and can adapt to wind-induced vibration control of large-scale structures in the uncertain dynamic circumstance.

关键词： torsional buffeting     large-scale     semiactive     adjustable frequency     building aeroelastic    

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Underlying mechanism of the hydrothermal instability of Cu

Nadeen Al-Janabi,Abdullatif Alfutimie,Flor R. Siperstein,Xiaolei Fan

《化学科学与工程前沿（英文）》 2016年 第10卷 第1期   页码 103-107 doi: 10.1007/s11705-015-1552-0

摘要： Water induced decomposition of Cu (BTC) (BTC= benzene-1,3,5-tricarboxylate) metal-organic framework (MOF) was studied using dynamic water vapour adsorption. Small-angle X-ray scattering, Fourier transform infrared spectroscopy and differential scanning calorimetry analyses revealed that the underlying mechanism of Cu (BTC) MOF decomposition under humid streams is the interpenetration of water molecules into Cu-BTC coordination to displace organic linkers (BTC) from Cu centres.

关键词： hydrothermal stability     metal-organic framework (MOF)     open metal sites (OMSs)     dynamic water vapour adsorption    

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Review of aeroelasticity for wind turbine: Current status, research focus and future perspectives

Pinting ZHANG, Shuhong HUANG

《能源前沿（英文）》 2011年 第5卷 第4期   页码 419-434 doi: 10.1007/s11708-011-0166-6

摘要： Aeroelasticity has become a critical issue for Multi-Megawatt wind turbine due to the longer and more flexible blade. In this paper, the development of aeroelasticity and aeroelastic codes for wind turbine is reviewed and the aeroelastic models for wind turbine blade are described, based on which, the current research focuses for large scale wind turbine are discussed, including instability problems for onshore and offshore wind turbines, effects of complex inflow, nonlinear effects of large blade deflection, smart structure technologies, and aerohydroelasticity. Finally, the future development of aeroelastic code for large scale wind turbine: aeroservoelasticity and smart rotor control; nonlinear aeroelasticity due to large blade deflection; full-scale 3D computational fluid dynamics (CFD) solution for dynamics; and aerohydroelasticity are presented.

关键词： wind turbine     aeroelasticity     aeroelastic code    

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Mechanisms and impacts of chromosomal translocations in cancers

null

《医学前沿（英文）》 2012年 第6卷 第3期   页码 263-274 doi: 10.1007/s11684-012-0215-5

摘要：

Chromosomal aberrations have been associated with cancer development since their discovery more than a hundred years ago. Chromosomal translocations, a type of particular structural changes involving heterologous chromosomes, have made a critical impact on diagnosis, prognosis and treatment of cancers. For example, the discovery of translocation between chromosomes 9 and 22 and the subsequent success of targeting the fusion product BCR-ABL transformed the therapy for chronic myelogenous leukemia. In the past few decades, tremendous progress has been achieved towards elucidating the mechanism causing chromosomal translocations. This review focuses on the basic mechanisms underlying the generation of chromosomal translocations. In particular, the contribution of frequency of DNA double strand breaks and spatial proximity of translocating loci is discussed.

关键词： DNA double strand breaks     chromosomal translocations     genomic instability     spatial proximity     carcinogenesis    

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p-Cresyl sulfate promotes the formation of atherosclerotic lesions and induces plaque instability by

null

《医学前沿（英文）》 2016年 第10卷 第3期   页码 320-329 doi: 10.1007/s11684-016-0463-x

摘要：

Coronary atherosclerosis is a major complication of chronic kidney disease. This condition contributes to the increased mortality in dialysis patients. p-Cresyl sulfate (PCS) is a prototype of protein-bound uremic toxins that cannot be efficiently removed through routine dialysis procedures. In the present study, ApoE−/− mice that underwent 5/6 nephrectomy were randomly divided into two groups, namely, vehicle-treated group (n = 20) and PCS-treated group (n = 20). Mice were sacrificed for en face and immunohistological analyses after 8 or 24 weeks of high-fat diet. Rat aortic vascular smooth muscle cells (VSMCs) were treated with phosphate buffer solution or 500 µmol/L PCS for in vitro evaluation. PCS-treated mice were observed to suffer increased atherosclerotic lesions after eight weeks of PCS administration. Moreover, 24 weeks of PCS administration also markedly increased the vulnerability index of aortic plaques. PCS was also observed to facilitate the migration and proliferation of VSMCs during the progression of the disease. Moreover, PCS disturbed the balance between matrix metalloproteinases and tissue inhibitor of metalloproteinases within the plaques. Thus, PCS played a vital role in promoting atherogenesis and disturbing the stability of formed plaques probably by targeting VSMCs.

关键词： p-cresyl sulfate     atherosclerosis     plaque stability     vascular smooth muscle cell    

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Aerodynamic stability evolution tendency of suspension bridges with spans from 1000 to 5000 m

《结构与土木工程前沿（英文）》 doi: 10.1007/s11709-023-0980-z

摘要： Aerodynamic instability owing to aerostatic and flutter-related failures is a significant concern in the wind-resistant design of long-span suspension bridges. Based on the dynamic characteristics of suspension bridges with spans ranging from 888 to 1991 m, we proposed fitted equations for increasing spans and base frequencies. Finite element models of suspension bridges with increasing span from 1000 to 5000 m were constructed. The structural parameters were optimized to follow the fitted tendencies. To analyze the aerodynamic instability, streamlined single-box section (SBS), lattice truss section (LTS), narrow slotted section (NSS), and wide slotted section (WSS) were considered. We performed three-dimensional (3-D) full-mode flutter analysis and nonlinear aerostatic instability analysis. The flutter critical wind speed continuously decreases with span growth, showing an unlimited approaching phenomenon. Regarding aerostatic instability, the instability wind speed decreases with span to approximately 3000 m, and increases when the span is in the range of 3000 to 5000 m. Minimum aerostatic instability wind speed with SBS or LTS girder would be lower than observed maximal gust wind speed, indicating the probability of aerostatic instability. This study proposes that suspension bridge with span approximately 3000 m should be focused on both aerostatic instability and flutter, and more aerodynamic configuration optimistic optimizations for flutter are essential for super long-span suspension bridges with spans longer than 3000 m.

关键词： suspension bridge     super long-span     finite element model     aerodynamic instability     aerodynamic configuration    

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Stability of an annular viscous liquid jet in compressible gases with different properties inside and outside of the jet

Chunji YAN, Maozhao XIE,

《能源前沿（英文）》 2010年 第4卷 第2期   页码 198-204 doi: 10.1007/s11708-009-0054-5

摘要： A spatial linear instability analysis is conducted on an annular viscous liquid jet injected into compressible gases and a three-dimensional model of the jet is developed. The model takes into account differences between the velocities, densities of the gases inside and outside of the liquid jet. Theoretical analysis reveals that there exist 9 dimensionless parameters controlling the instability of the liquid jet. Numerical computations reveal some basic characteristics in the breakup and atomization process of the liquid jet as well as influences of these relevant parameters. Major observations and findings of this study are as follows. The Mach number plays a destabilizing role and the inner Mach number has a greater effect on the jet instability than the outer Mach number. The Reynolds number always tends to promote the instabilities of the liquid jet, but its influence is very limited. The Weber number and the gas-to-liquid density ratio also have unstable effects and can improve the atomization of liquid jets. Furthermore, the effects of the Weber number and gas-to-liquid density ratio on the maximum growth rates of axisymmetric and non-axisymmetric disturbances and corresponding dominant wave numbers are manifested in a linear way, while that of the Mach number is non-linear. The effect of Reynolds on the maximum growth rates is non-linear, but the dominant wavenumber is almost not affected by the Reynolds number.

关键词： liquid jet     dominant wave number     compressibility     instability    

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湍流效应对桁架式桥梁断面气动弹性性能影响的研究

Hoang Trong Lam, Hiroshi Katsuchi, Hitoshi Yamada

《工程（英文）》 2017年 第3卷 第6期   页码 845-853 doi: 10.1016/j.eng.2017.10.001

摘要：
本文介绍了在不同湍流条件下通过随机系统识别（SSI）方法提取颤振导数（FD）的过程。研究旨在通过对节段模型风洞试验来研究湍流对悬索式大跨度桥梁的影响。针对不同的湍流特性，对桁架式桥梁断面进行了几项风洞试验，包括降低湍流强度和湍流尺度。研究包括湍流对模型动态响应的影响。利用系统识别技术提取FD，对风洞试验中的瞬态响应和抖振响应进行了分析，同时讨论了该方法存在的困难。利用时域SSI 同时从一自由度（1DOF）和二自由度（2DOF）系统提取所有的FD。最后，讨论了不同情况下的结果并得出结论。

关键词： 颤振导数     系统识别     湍流效应     抖振响应    

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Emergent limited perioperative transesophageal echocardiography: should new guidelines exist for limited echocardiography training for anesthesiologists?

null

《医学前沿（英文）》 2012年 第6卷 第3期   页码 332-337 doi: 10.1007/s11684-012-0212-8

摘要：

Bedside limited echocardiography, or focused cardiac ultrasound, continues to gain popularity in many emergency rooms, intensive care units, and operating rooms as a rapid method of assessing unstable patients. Effective monitoring of cardiovascular function in conditions like cardiac arrest or near-arrest is the crucial step to guide successful resuscitative efforts. Transesophageal echocardiography (TEE) has emerged as one of the preferred cardiac diagnostic and monitoring modalities in the intraoperative setting due to the fact that it is less invasive than many other monitors, is immediately accessible, and allows for continuous real-time monitoring of cardiac function. However, the minimum training requirements needed for the anesthesia provider to obtain the competency, knowledge, and skills for basic certification in perioperative TEE far exceed those developed for other medical specialties. We believe there is an urgent need to develop (1) practical guidelines for emergent perioperative TEE use for anesthesiologists and (2) a requisite educational curriculum to teach the basic skills necessary to aid in the diagnosis and treatment of cardiac arrest or near-arrest scenarios. The measures elucidated in this report summarize the efforts of the Department of Anesthesiology at the University of Florida in establishing the necessary steps to make this process not only practical, but accessible to all trainees. We hope that these collective efforts will provide more trainees the confidence in utilizing TEE to aid in establishing a diagnosis in critical situations.

关键词： transesophageal echocardiography     curriculum     competency training     hemodynamic instability    

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标题 作者 时间 类型 操作

A novel structural modification to eliminate the early coupling between bending and torsional mode shapes in a cable stayed bridge

Nazim Abdul NARIMAN

期刊论文

Mean wind load induced incompatibility in nonlinear aeroelastic simulations of bridge spans

Zhitian ZHANG

期刊论文

Combustion instability detection using the wavelet detail of pressure fluctuations

JI Junjie, LUO Yonghao

期刊论文

海底不稳定性研究进展及展望

高伟健,李伟

期刊论文

表面张力作用下柱形胶体的弹性失稳

黄殿武,乔玲,汪时机

期刊论文

工程饱和介质中漩涡光的调制不稳定性

D.G. Pires, N.M. Litchinitser

期刊论文

Control of wind-induced vibration of long-span bridges and tall buildings

GU Ming

期刊论文

Underlying mechanism of the hydrothermal instability of Cu

Nadeen Al-Janabi,Abdullatif Alfutimie,Flor R. Siperstein,Xiaolei Fan

期刊论文

Review of aeroelasticity for wind turbine: Current status, research focus and future perspectives

Pinting ZHANG, Shuhong HUANG

期刊论文

Mechanisms and impacts of chromosomal translocations in cancers

null

期刊论文

p-Cresyl sulfate promotes the formation of atherosclerotic lesions and induces plaque instability by

null

期刊论文

Aerodynamic stability evolution tendency of suspension bridges with spans from 1000 to 5000 m

期刊论文

Stability of an annular viscous liquid jet in compressible gases with different properties inside and outside of the jet

Chunji YAN, Maozhao XIE,

期刊论文

湍流效应对桁架式桥梁断面气动弹性性能影响的研究

Hoang Trong Lam, Hiroshi Katsuchi, Hitoshi Yamada

期刊论文

Emergent limited perioperative transesophageal echocardiography: should new guidelines exist for limited echocardiography training for anesthesiologists?

null

期刊论文