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Comparisons of bridges flutter derivatives and generalized ones

Fuyou XU , Zhe ZHANG , Cailiang HUANG , Airong CHEN ,

《结构与土木工程前沿（英文）》 2009年 第3卷 第3期   页码 272-278 doi: 10.1007/s11709-009-0042-1

摘要： The causes of the nonlinearity of self-excited aerodynamic force of bridge are interpreted from such two aspects as amplitude and wind velocity. The concept of “generalized flutter derivative” is proposed, and its physical meaning is illustrated. The graphs of the generalized flutter derivatives of plate and Sutong Bridge section model are plotted. The characteristics of all generalized flutter derivatives are compared and analyzed, and their superiorities are verified. The results indicate that the physical meaning of generalized flutter derivatives are more explicit compared to the traditional ones. It is more convenient to understand the nonlinearity properties of self-excited aerodynamic force of bridge according to the generalized flutter derivatives graphs with the wind velocity as the horizontal coordinate.

关键词： bridge     flutter derivative     generalized flutter derivative     self-excited aerodynamic force     Sutong Bridge    

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Time-domain and frequency-domain approaches to identification of bridge flutter derivatives

Zhengqing CHEN

《结构与土木工程前沿（英文）》 2009年 第3卷 第2期   页码 173-179 doi: 10.1007/s11709-009-0034-1

摘要： Flutter derivatives are essential for flutter analysis of long-span bridges, and they are generally identified from the vibration testing data of a sectional model suspended in a wind tunnel. Making use of the forced vibration testing data of three sectional models, namely, a thin-plate model, a nearly streamlined model, and a bluff-body model, a comparative study was made to identify the flutter derivatives of each model by using a time-domain method and a frequency-domain method. It was shown that all the flutter derivatives of the thin-plate model identified with the frequency-domain method and time-domain method, respectively, agree very well. Moreover, some of the flutter derivatives of each of the other two models identified with the two methods deviate to some extent. More precisely, the frequency-domain method usually results in smooth curves of the flutter derivatives. The formulation of time-domain method makes the identification results of flutter derivatives relatively sensitive to the signal phase lag between vibration state vector and aerodynamic forces and also prone to be disturbed by noise and nonlinearity.

关键词： long-span bridges     wind-induced vibration     flutter derivatives     forced vibration test     time-domain method     frequency-domain method    

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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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千米级斜拉桥空气动力学问题

陈艾荣,马如进,王达磊

《中国工程科学》 2009年 第11卷 第3期   页码 31-37

摘要：

以苏通大桥为背景，对超大跨径斜拉桥的空气动力学问题进行了研究，着重讨论了超大跨径斜拉桥的动力特性、风荷载、基于气弹模型的颤振导数识别、结构体系以及涡激振动特性等一系列问题。研究结果表明，考虑侧向风荷载作用下斜拉索的非线性效应之后，全桥结构的竖向刚度有折减现象。同时发现Fixed - Fixed体系是解决顺桥向风荷载的有效途径还提出了基于气弹模型的颤振导数识别方法，并就斜拉桥的涡激振动和雷诺数效应进行了探讨。

关键词： 苏通大桥斜拉桥     动力特性     合理体系     雷诺数效应     颤振导数    

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Evaluation of 1,4-naphthoquinone derivatives as antibacterial agents: activity and mechanistic studies

《环境科学与工程前沿（英文）》 2023年 第17卷 第3期 doi: 10.1007/s11783-023-1631-2

摘要：

● All 1,4-naphthoquinone hybrids exhibited significant antimicrobial activity.

关键词： 1     4-naphthoquinone derivatives     Antibacterial     Action mechanism     RecA    

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Discovery of cryptolepine derivatives as novel promising agents against phytopathogenic bacteria

《化学科学与工程前沿（英文）》 2023年 第17卷 第2期   页码 156-166 doi: 10.1007/s11705-022-2196-5

摘要： To ensure the production of food crops, a series of cryptolepine derivatives were synthesised, after which their antibacterial activities and mechanism of action against three plant pathogens were investigated. Our bioassay results indicated that most of the target compounds displayed potent inhibitory effects against Xanthomonas oryzae (X. oryzae) and Xanthomonas axonopodis pv. citri (X. axonopodis pv. c.). Remarkably, compound 9 exhibited the best in vitro antibacterial activity against X. oryzae, with a minimum inhibitory concentration (MIC) value of 0.78 μg·mL–1. Compound 2 exhibited the best in vitro antibacterial activity against X. axonopodis pv. c., with an MIC value of 0.39 μg·mL–1. These activities were superior to those of copper quinolate (MIC = 6.25, 25 μg·mL–1) and thiodiazole copper (MIC = 100, 200 μg·mL–1) against X. oryzae and X. axonopodis pv. c. In vivo experiments demonstrated the promising applicability of compound 9 for the control of rice bacterial infections. Furthermore, compound 9 was selected as a candidate to conduct preliminary analyses of the antibacterial mechanisms of cryptolepine derivatives. Scanning electron microscopy and transmission electron microscopy observations, extracellular polysaccharide production, biofilm formation, transcriptomic, quantitative reverse transcription-polymerase chain reaction analyses, and molecular docking assays were performed. Collectively, our findings demonstrated that compound 9 might act via multifarious mechanisms to down-regulate virulence factors and cause cell death.

关键词： cryptolepine derivatives     phytopathogenic bacteria     antibacterial activity     mechanism of action    

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Flutter control effect and mechanism of central-slotting for long-span bridges

YANG Yongxin, GE Yaojun, XIANG Haifan

《结构与土木工程前沿（英文）》 2007年 第1卷 第3期   页码 298-304 doi: 10.1007/s11709-007-0039-6

摘要： The flutter control effect and mechanism of central-slotting, which have gradually been adopted in the design and construction of long-span bridges as an effective flutter controlling measure, were investigated with theoretical analysis and wind tunnel test. Five basic girder cross-sections representing five typical aerodynamic configurations were selected and central-slotted with two different slot widths. Then, a series of sectional model tests and theoretical analyses based on the two-dimensional three-degrees-of-freedom coupling flutter analysis method (2 dimension-3 degrees of freedom method, 2d-3DOF method) were carried out to investigate the aerodynamic performance, flutter mechanism and flutter modality of the five basic sections and their corresponding central-slotted sections. The results show that central-slotting can not always improve the aerodynamic stability of bridge structure. The control effect of central-slotting depends on the aerodynamic configuration of the original girder section and the corresponding central-slotting width. If the original section is inappropriate or the slot width is unsuitable, central-slotting will even deteriorate the structural flutter performance. Theoretical investigations indicated that the differences in flutter control effects come from the different formation and evolution of aerodynamic damping, and flutter modality especially the participation level of heaving motion also has a significant influence on the control effect of central-slotting.

关键词： aerodynamic configuration     aerodynamic performance     flutter mechanism     aerodynamic stability     theoretical analysis    

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Synthesis, insecticidal activities and DFT study of pyrimidin-4-amine derivatives containing the 1,2,4

《化学科学与工程前沿（英文）》 2022年 第16卷 第7期   页码 1090-1100 doi: 10.1007/s11705-021-2091-5

摘要： Twenty six novel pyrimidin-4-amine derivatives containing the 1,2,4-oxadiazole motif were synthesized. Their chemical structures were confirmed by 1H nuclear magnetic resonance (NMR), 13C NMR, and high-resolution mass spectrography. The insecticidal activity results indicated that some of them possessed excellent insecticidal activity (100%) against Mythimna separate, especially for compounds 6d, 6f, 6o, 6w, 6y and 6z. These compounds exhibited no activity against the insects Aphis medicagini and Tetranychus cinnabarinus. The structure- insecticidal activity relationships are discussed. Density functional theory analysis can potentially be used to design more active compounds. These results provide useful insecticide design information for further optimization.

关键词： synthesis     pyrimidin-4-amine derivatives     1     2     4-oxadiazole     insecticidal activity     structure-activity relationship    

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泰州大桥主梁施工阶段的颤振稳定性及管理对策

李承宬,陈艾荣,马如进

《中国工程科学》 2012年 第14卷 第5期   页码 46-50

摘要：

以三塔两跨的泰州大桥为研究对象，根据有限元分析及全桥气弹模型风洞试验的结果，对主梁对称架设施工阶段的动力特性及颤振稳定性进行了研究。结合桥位地区30年的月极大风速分析，对主梁架设阶段的颤振稳定性进行了评价。最后提出了一套针对悬索桥施工阶段颤振稳定性评价及策略确定的流程，可供其他桥梁参考。

关键词： 多塔悬索桥     施工阶段     颤振稳定性     管理对策    

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Discovery of novel ursolic acid derivatives as effective antimicrobial agents through a ROS-mediated

《化学科学与工程前沿（英文）》 2023年 第17卷 第12期   页码 2101-2113 doi: 10.1007/s11705-023-2361-5

摘要： In response to the reduction of food production and economic losses caused by plant bacterial diseases, it is necessary to develop new, efficient, and green pesticides. Natural products are rich and sustainable source for the development of new pesticides due to their low toxicity, easy degradation, and eco-friendliness. In this study, we prepared three series of ursolic acid derivatives and assessed their antibacterial ability. Most target compounds exhibited outstanding antibacterial activities. Among them, the relative optimal EC50 values of Xanthomonas oryzae pv. oryzae and Xanthomonas axonopodis pv. citri were 2.23 (A17) and 1.39 (A16) μg·mL–1, respectively. The antimicrobial mechanism showed that compound A17 induced an excessive accumulation and production of reactive oxygen species in bacteria and damaged the cell membrane integrity to kill bacteria. More interestingly, the addition of low concentrations of exogenous hydrogen peroxide enhanced the antibacterial efficacy of compound A17 against Xanthomonas oryzae pv. oryzae. These entertaining results suggested that compound A17 induced an apparent apoptotic behavior in the tested bacteria. Overall, we developed the promising antimicrobial agents that destroyed the redox system of phytopathogenic bacteria, further demonstrating the unprecedented potential of ursolic acid for agricultural applications.

关键词： ursolic acid     antibacterial activities     reactive oxygen species     apoptosis    

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efficiency optimization and Sobol’s sensitivity indices of MTMDs design parameters for buffeting and flutter

Nazim Abdul NARIMAN

《结构与土木工程前沿（英文）》 2017年 第11卷 第1期   页码 66-89 doi: 10.1007/s11709-016-0356-8

摘要： This paper studies optimization of three design parameters (mass ratio, frequency ratio and damping ratio) of multiple tuned mass dampers MTMDs that are applied in a cable stayed bridge excited by a strong wind using minimax optimization technique. ABAQUS finite element program is utilized to run numerical simulations with the support of MATLAB codes and Fast Fourier Transform FFT technique. The optimum values of these three parameters are validated with two benchmarks from the literature, first with Wang and coauthors and then with Lin and coauthors. The validation procedure detected a good agreement between the results. Box-Behnken experimental method is dedicated to formulate the surrogate models to represent the control efficiency of the vertical and torsional vibrations. Sobol’s sensitivity indices are calculated for the design parameters in addition to their interaction orders. The optimization results revealed better performance of the MTMDs in controlling the vertical and the torsional vibrations for higher mode shapes. Furthermore, the calculated rational effects of each design parameter facilitate to increase the control efficiency of the MTMDs in conjunction with the support of the surrogate models.

关键词： MTMDs     power spectral density     fast Fourier transform     minimax optimization technique     Sobol’s sensitivity indices     Box-Behnken method    

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Computational fluid dynamic analysis of flutter characteristics for self-anchored suspension bridges

ZHU Zhiwen, WANG Zhaoxiang, CHEN Zhengqing

《结构与土木工程前沿（英文）》 2008年 第2卷 第3期   页码 267-273 doi: 10.1007/s11709-008-0034-6

摘要： This paper outlines the essentials and procedures of computational fluid dynamics (CFD) simulation applicable to evaluating flutter derivatives of bridge decks. An arbitrary Lagrangian-Eulerian (ALE) description of the flow around the moving rigid box girder combined with the finite volume discretization and multi-grid algorithm is presented. The proposed methods are employed to identify flutter derivatives of the bridge deck of the Sanchaji Self-anchored Suspension Bridge. The results agree well with ones from wind tunnel tests. It demonstrates accuracy and efficiency of the present method.

关键词： discretization     computational     description     Self-anchored Suspension     simulation applicable    

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Synthesis and ultraviolet/aggregation-induced emission investigation of novel tetraphenylvinyl hydrazone derivatives

《化学科学与工程前沿（英文）》 2023年 第17卷 第12期   页码 2061-2073 doi: 10.1007/s11705-023-2366-0

摘要： Herein, three novel tetraphenylethylene hydrazone chemosensors TC12, SC16, and TC16 are prepared for the selective detection of F−. Two NH and one C=N units are incorporated into the sensors for better colorimetric responses, whereas the tetraphenyl unit is in charge of the aggregation-induced emission effect. Among them, compounds SC16 and TC16 form stable gels with some organic solvents. All the tetrahydrofuran/H2O solutions of the three compounds exhibit aggregation-induced emission effect, whereby the fluorescence emission increases by varying degrees with the volume of poor solvent water. Moreover, good aggregation-induced emission effects are observed in the self-assembly of SC16 and TC16. As a sample chemosensor, TC12 in tetrahydrofuran responds to F− selectively with high sensitivity, with the colorimetric and fluorometric detection limits of 8.25 × 10−7 mol·L–1 and 2.69 × 10−7 mol·L–1, respectively. The reversible gel-sol-gel phase transition and color changes indicate that both SC16-dimethyl sulfoxide and TC16-ethyl acetate gels specifically respond to F– with good sensitivity. The detection results are well supported by ultraviolet-visible spectroscopy, fluorescent spectroscopy, and 1H nuclear magnetic resonance. More importantly, the driving forces of gelation are visually clarified through the single crystal X-ray analysis of compound TOMe.

关键词： organogelator     tetraphenylvinyldrazone     single crystal     aggregation-induced emission effect     ion sensing    

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基于气动模型的大跨度桥梁抖振与颤振的比较评估

Igor Kavrakov, Guido Morgenthal

《工程（英文）》 2017年 第3卷 第6期   页码 823-838 doi: 10.1016/j.eng.2017.11.008

摘要：
风致振动通常代表了大跨度桥梁设计的主要标准。桥梁空气动力学中的气动力主要基于准定常和线性非定常理论。本文旨在通过比较多跨斜拉桥在临界架设条件下的动力响应，进而推演出不同时域自激力与抖振力的表达式。这类混凝土箱梁桥是用于大型河流交叉口的典型参考对象。本文从模型复杂性的角度进行分析，对比了气动模型中隐含的气动参数，如气动阻尼和气动刚度、抖振力和自激力中的流体记忆、气动非线性和气动耦合等对桥梁响应的影响。选定的模型用于研究一定风速范围内的结果，该风速范围对于考虑两种湍流度情况的施工过程是典型范围。此外，还提出了一种计算包括气动导纳在内的抖振力的简化方法，避免了有理逼近。在层流流动下，也将对根据所选模型计算得到的临界颤振风速进行对比。

关键词： 抖振     颤振     大跨度桥梁     桥梁空气动力学     桥梁气动弹性     架设阶段    

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Effect of graphene and its derivatives on thermo-mechanical properties of phase change materials and

《能源前沿（英文）》 2022年 第16卷 第2期   页码 150-186 doi: 10.1007/s11708-021-0795-3

摘要： Phase change materials (PCMs) play a leading role in overcoming the growing need of advanced thermal management for the storage and release of thermal energy which is to be used for different solar applications. However, the effectiveness of PCMs is greatly affected by their poor thermal conductivity. Therefore, in the present review the progress made in deploying the graphene (Gr) in PCMs in the last decade for providing the solution to the aforementioned inadequacy is presented and discussed in detail. Gr and its derivatives ((Gr oxide (GO), Gr aerogel (GA) and Gr nanoplatelets (GNPs)) based PCMs can improve the thermal conductivity and shape stability, which may be attributed to the extra ordinary thermo-physical properties of Gr. Moreover, it is expected from this review that the advantages and disadvantages of using Gr nanoparticles provide a deep insight and help the researchers in finding out the exact basic properties and finally the applications of Gr can be enhanced.

关键词： phase change materials (PCMs)     graphene     thermal conductivity     characterization    

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标题 作者 时间 类型 操作

Comparisons of bridges flutter derivatives and generalized ones

Fuyou XU , Zhe ZHANG , Cailiang HUANG , Airong CHEN ,

期刊论文

Time-domain and frequency-domain approaches to identification of bridge flutter derivatives

Zhengqing CHEN

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

千米级斜拉桥空气动力学问题

陈艾荣,马如进,王达磊

期刊论文

Evaluation of 1,4-naphthoquinone derivatives as antibacterial agents: activity and mechanistic studies

期刊论文

Discovery of cryptolepine derivatives as novel promising agents against phytopathogenic bacteria

期刊论文

Flutter control effect and mechanism of central-slotting for long-span bridges

YANG Yongxin, GE Yaojun, XIANG Haifan

期刊论文

Synthesis, insecticidal activities and DFT study of pyrimidin-4-amine derivatives containing the 1,2,4

期刊论文

泰州大桥主梁施工阶段的颤振稳定性及管理对策

李承宬,陈艾荣,马如进

期刊论文

Discovery of novel ursolic acid derivatives as effective antimicrobial agents through a ROS-mediated

期刊论文

efficiency optimization and Sobol’s sensitivity indices of MTMDs design parameters for buffeting and flutter

Nazim Abdul NARIMAN

期刊论文

Computational fluid dynamic analysis of flutter characteristics for self-anchored suspension bridges

ZHU Zhiwen, WANG Zhaoxiang, CHEN Zhengqing

期刊论文

Synthesis and ultraviolet/aggregation-induced emission investigation of novel tetraphenylvinyl hydrazone derivatives

期刊论文

基于气动模型的大跨度桥梁抖振与颤振的比较评估

Igor Kavrakov, Guido Morgenthal

期刊论文

Effect of graphene and its derivatives on thermo-mechanical properties of phase change materials and

期刊论文