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Review and comparison of methods and benchmarks for automatic modal identification based on stabilization diagram

Journal of Traffic and Transportation Engineering(English Edition) 2024年第2期11卷 209-224页

作者： Min He Peng liang Jiuxian Liu Zhiqiang liang School of Architecture and Civil Engineering Xi'an University of Science and TechnologyXi'an 710064China School of Highway Chang'an UniversityXi'an 710064China

Automatic modal identification via automatically interpreting the stabilization diagram provides key technique in bridge structural health *** paper reviews the progress in the area of automatic modal identification based on interpreting the stabilization *** whole identification process is divided into four steps from establishing the stabilization diagram to removing the outliers in the identification *** criteria and algorithms used in each step in the existing studies are carefully summarized and *** between typical methods in cleaning and interpreting the stabilization diagram are also *** structure benchmarks used in the existing studies to validate the proposed automatic modal identification methods are also *** on the review and comparison,the specific ratio method for cleaning the stabilization diagram,the hierarchical clustering method for interpreting the stabilization diagram and the adjusted boxplot for removing the outliers in the identification results are the most suitable methods for each *** key point of automatic modal identification based on interpreting the stabilization diagram has also discussed,and it is recommended to pay more attention to cleaning the stabilization *** study about automatic modal identification under situation with very few sensors deployed should be more *** review aims to help researchers and practitioners in implementing existing automatic modal identification algorithms effectively and developing more suitable and practical methods for civil engineering structures in the future.

关键词： Bridge structural health monitoring Automatic modal identification Stabilization diagram Eriteria and methods Real structure benchmarks

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Time-domain Differential Protection Based on Operating and Restraining Trajectory Indices for Lines Connecting Battery Storage Energy Stations

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Journal of Modern Power Systems and Clean Energy 2024年第4期12卷 1074-1086页

作者： Yingyu liang Cunyue Pan School of Mechanical and Electrical Engineering China University of Mining and Technology(Beijing)BeijingChina

Battery energy storage stations(BESSs)pose sever-al challenges for both phasor-based differential protection and the newly-proposed time-domain differential *** challenges include low sensitivity and even ***,the negative impact of various nonideal conditions,including current transformer(CT)saturation,errors,and outliers,on the security of differential protection remains an important *** by the aforementioned issues,this study ac-counts for the trajectory distribution discrepancy on Cartesian plane under various conditions and proposes a time-domain dif-ferential protection *** this paper,the trajectory formed by operating and restraining current samples is ***,after considering different operating states,the fault severity levels,and nonideal conditions,the variances in trajectory distribution between internal and external faults are extensively *** this basis,the Cartesian plane is divided into operating,uncertainty,and restraining ***-ther,the operating and restraining trajectory indices are meticu-lously designed and a protection criterion based on these indi-ces is formed to accurately separate internal faults from other events,unaffected by CT saturation,errors,and *** exceptional performance of the proposed protection method is extensively validated through PSCAD simulations and a hard-ware-in-the-loop testing *** the dependability,sensitivity,and security,the proposed protection method outper-forms three state-of-the-art differential protection methods.

关键词： Battery energy storage station time-domain differential protection operating trajectory index(OTI) restraining trajectory index(RTI)

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广州开发区公共服务空间配置特征及优化路径研究

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城市观察 2021年第2期72卷 75-84页

作者：武文杰梁慧诗暨南大学经济学院暨南大学经济学院特区港澳经济研究所

以广州开发区为案例,探讨政府作用力作为主力的建设以及与行政区管理体制的深度融合是广州开发区公共服务建设的重要特征,并提出目前广州市开发区的公共服务设施与区内社会经济发展和人口结构不相适应的问题,最后提出善用政府作用力建... 详细信息

以广州开发区为案例,探讨政府作用力作为主力的建设以及与行政区管理体制的深度融合是广州开发区公共服务建设的重要特征,并提出目前广州市开发区的公共服务设施与区内社会经济发展和人口结构不相适应的问题,最后提出善用政府作用力建设公共服务,坚持管理体制的深度融合,以及发挥社区作用发展老龄友好公共服务设施三个优化路径。

关键词：公共服务设施广州开发区空间配置优化

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Evaluation of frictional pressure drop correlations for air-water and air-oil two-phase flow in pipeline-riser system

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Petroleum Science 2024年第2期21卷 1305-1319页

作者： Nai-liang Li Bin Chen School of Low-carbon Energy and Power Engineering China University of Mining and TechnologyXuzhou221116JiangsuChina State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an710049ShaanxiChina

Accurate prediction of the frictional pressure drop is important for the design and operation of subsea oil and gas transporting system considering the length of the pipeline. The applicability of the correlations to pipeline-riser flow needs evaluation since the flow condition in pipeline-riser is quite different from the original data where they were derived from. In the present study, a comprehensive evaluation of 24prevailing correlation in predicting frictional pressure drop is carried out based on experimentally measured data of air-water and air-oil two-phase flows in pipeline-riser. Experiments are performed in a system having different configuration of pipeline-riser with the inclination of the downcomer varied from-2°to-5°to investigated the effect of the elbow on the frictional pressure drop in the riser. The inlet gas velocity ranges from 0.03 to 6.2 m/s, and liquid velocity varies from 0.02 to 1.3 m/s. A total of885 experimental data points including 782 on air-water flows and 103 on air-oil flows are obtained and used to access the prediction ability of the correlations. Comparison of the predicted results with the measured data indicate that a majority of the investigated correlations under-predict the pressure drop on severe slugging. The result of this study highlights the requirement of new method considering the effect of pipe layout on the frictional pressure drop.

关键词： Frictional pressure drop Pipeline-riser Gas-liquid two-phase flow Severe slugging Correlation

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Securing offshore resources development: A mathematical investigation into gas leakage in long-distance flexible pipes

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Petroleum Science 2024年第4期21卷 2734-2744页

作者： Xiang-An Lu liang-liang Jiang Jian-Sheng Zhang Min-Gui Wang Guangling College of Yangzhou University Department of Chemical and Petroleum Engineering University of Calgary Department of Energy and Power Engineering Tsinghua University

Gas flexible pipes are critical multi-layered equipment for offshore oil and gas development. Under high pressure conditions, small molecular components of natural gas dissolve into the polymer inner liner of the flexible pipes and further diffuse into the annular space, incurring annular pressure build-up and/or production of acidic environment, which poses serious challenges to the structure and integrity of the flexible pipes. Gas permeation in pipes is a complex phenomenon governed by various factors such as internal pressure and temperature, annular structure, external temperature. In a long-distance gas flexible pipe, moreover, gas permeation exhibits non-uniform features, and the gas permeated into the annular space flows along the metal gap. To assess the complex gas transport behavior in long-distance gas flexible pipes, a mathematical model is established in this paper considering the multiphase flow phenomena inside the flexible pipes, the diffusion of gas in the inner liner, and the gas seepage in the annular space under varying permeable properties of the annulus. In addition, the effect of a variable temperature is accounted. A numerical calculation method is accordingly constructed to solve the coupling mathematical equations. The annular permeability was shown to significantly influence the distribution of annular pressure. As permeability increases, the annular pressure tends to become more uniform, and the annular pressure at the wellhead rises more rapidly. After annular pressure relief followed by shut-in, the pressure increase follows a convex function. By simulating the pressure recovery pattern after pressure relief and comparing it with test results, we deduce that the annular permeability lies between 123 and 512 m D. The results help shed light upon assessing the annular pressure in long distance gas flexible pipes and thus ensure the security of gas transport in the emerging development of offshore resources.

关键词： Offshore resources development Transport security Long-distance flexible pipes Gas leakage Heat and mass transfer model Finite difference calculation

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An Anisotropic Biomimetic Lemongrass Flexible Piezoelectric Actuator-Inhibitory Regression

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Journal of Bionic Engineering 2024年第4期21卷 1817-1829页

作者： Tianwei liang Yunhong liang Jiru Wang Hu Huang Zhi Xu Hongwei Zhao Key Laboratory of CNC Equipment Reliability Ministry of EducationJilin UniversityChangchun130022China School of Mechanical and Aerospace Engineering Jilin UniversityChangchun130022China Institute of Structured and Architected Materials Liaoning Academy of MaterialsShenyang110167China The Key Laboratory of Bionic Engineering Ministry of EducationJilin UniversityChangchun130025China

At present,the existing piezoelectric stick-slip actuators have an inherent back-slip problem,which greatly limits the development and application of stick-slip *** order to inhibit the regression phenomenon,a new bionic lemongrass stickslip actuator was prepared by using polymer PDMS to replicate natural biological *** surface microstructure of the grass was copied by PDMS,and the PDMS film was *** rigid and flexible bionic friction pair was further prepared,and the flexible anisotropic PDMS stick slip actuator was *** was found that the anisotropic friction characteristics of the surface microstructure of the grass inhibited the anti-sliding motion,and the elastic potential energy of the PDMS film improved the output characteristics of the *** adjusting the input voltage to control the contact between the drive foot and the rotor,the rigid and flexible hybrid drive can be realized and the backsliding phenomenon can be *** actuator is compact,lightweight and can achieve high speed and high resolution output without preloading force,which has important application value in the field of fast and accurate positioning with load limitation.

关键词： Piezoelectric actuator Bionic surface Friction Surface friction Flexible film

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Nest decoration:Black feathers prevent Crested Mynas from nest usurpation

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Avian Research 2024年第2期15卷 292-297页

作者： Jinmei Liu Wei liang Ministry of Education Key Laboratory for Ecology of Tropical Islands Key Laboratory of Tropical Animal and Plant Ecology of Hainan ProvinceCollege of Life SciencesHainan Normal UniversityHaikou571158China

Nests are important structures for birds to raise their offspring and for *** birds incorporate feathers into the nest,since feathers were traditionally thought to serve the function of *** in recent years have considered that some birds place feathers in conspicuous locations in the nest for decoration to trigger a fear response in the *** this study,we investigated whether decorative feathers could deter nest usurpation by Crested Mynas(Acridotheres cristatellus)by manipulating nest box *** results revealed that Crested Mynas preferred black feathers to white feathers as decorations and occupied nest boxes decorated with black feathers significantly less than those decorated with white feathers,suggesting that black decorative feathers in the nest could be more effective in preventing nest usurpation by Crested Mynas and that white decorative feathers may have other *** black feathers in the nest are prominently placed at the edge of the nest to convey the message that“this nest is occupied”or“the owner of this nest has been preyed upon”to visitor Crested Mynas,thus effectively preventing them from usurping the nest at a later stage.

关键词： Extended phenotype Feathers Nest decoration Nest usurpation

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Screening of transition metal oxides for electrocatalytic nitrate reduction to ammonia at large currents

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Nano Research 2024年第5期17卷 3902-3910页

作者： Qiongfei Wu Weijie Zhu Dongxu Ma Chao liang Zhoucheng Wang Hanfeng liang State Key Laboratory of Physical Chemistry of Solid Surfaces Tan Kah Kee Innovation LaboratoryCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China College of Chemical Engineering Tianjin UniversityTianjin 300072China

Electrochemical nitrate reduction reaction(NO_(3)RR)towards ammonia,as an emerging and appealing technology alternative to the energy-intensive Haber-Bosch process and inefficient nitrogen reduction reaction,has recently aroused wide concern and ***,the current research of the NO_(3)RR towards ammonia lacks the overall performance comparison of various *** this,we here make a comparison of 12 common transition metal oxide catalysts for the NO_(3)RR under a high cathodic current density of 0.25 A·cm^(-2),wherein Co_(3)O_(4) catalyst displays the highest ammonia Faradaic efficiency(85.15%)and moderate activity(ca.-0.25 V *** hydrogen electrode).Other external factors,such as nitrate concentrations in the electrolyte and applied potential ranges,have also been specifically investigated for the NO_(3)RR.

关键词： nitrate reduction reaction ammonia production transition metal oxides Co_(3)O_(4)

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AFM probe for measuring~10^(−5)ultra-low friction coefficient:Design and application

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Friction 2024年第1期12卷 64-73页

作者： Yushan CHEN liang JIANG Linmao QIAN Tribology Research Institute State Key Laboratory of Traction PowerSouthwest Jiaotong UniversityChengdu 610031China

Superlubricity provides a novel approach to addressing friction and wear issues in mechanical ***,little is known regarding improving the atomic force microscope(AFM)friction coefficient measurement ***,this study established the theoretical formula for the AFM friction coefficient measurement and deduced the measurement ***,the formula was applied to the AFM probe with a rectangular cross-section *** measurement resolution is associated with the dimensional properties of the AFM probe,the mechanical properties of the cantilever material,the properties of the position-sensitive detector(PSD),and probably the anti-vibration performance of the *** is feasible to make the cantilever as short as possible and the tip as high as possible to improve the measurement *** AFM probe for measuring an ultra-low friction coefficient was designed and *** cantilever’s length,width,and thickness are 50,35,and 0.6μm,*** tip height is 23μ*** measurement resolution can reach 7.1×10^(−6) under the maximum normal ***,the AFM probe was applied to measure the superlubricity between graphene *** friction coefficient is 0.00139 under 853.08 *** work provides a promising method for measuring a~10^(−5) friction coefficient of superlubricity.

关键词： atomic force microscope(AFM) superlubricity friction coefficientμ probe

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Forming process chain for manufacturing complex conical-section profiled rings:On a co-design method

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Chinese Journal of Aeronautics 2024年第6期37卷 485-503页

作者： Lei liang Chaojiang ZOU lianggang GUO State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Guizhou Aviation Technology Development Co.Ltd Guiyang 550081China

The final quality of complex conical-section rings depends on co-design of multiple processes in forming process *** this study,for a complex aeroengine casing ring with a large slope and a flange on its end,a co-design method of the forming process chain is put forward towards the objective of precision forming,which not only proposes a standard process route composed of multiple processes of upsetting,punching,rectangular ring rolling,loose tooling forging and profiled ring rolling,but also presents co-design methods of dies and blanks for all the *** profiled ring rolling,a design method of preformed blank that makes the blank and the target conical-section ring have the same axial volume distribution is *** the method,the axial metal redistribution during the process can be alleviated greatly thus improving the forming stability and precision of the *** on the geometric features of designed preformed blank,design methods of blanks and dies for loose tolling forging,rectangular ring rolling,punching and upsetting are proposed *** view of the key roles of loose tooling forging(manufacturing the preformed blank)and profiled ring rolling on the final quality of the conical ring parts,inherited FE simulations for these two processes are performed to verify the proposed design methods and determine appropriate design *** is demonstrated that the proposed design method has significant advantages in improving forming ***,a suggestive value 1.5 of the rolling ratio for profiled ring rolling(a key design parameter)is given based on comprehensive consideration of multiple indicators such as ring roundness,deformation uniformity and forming *** corresponding industrial experiments performed illustrate that a high forming precision of the conical-section aeroengine casing ring is achieved.

关键词： Complex conical-section ring Co-design of forming process chain Profiled ringrolling Preformed blank Loose tooling forging

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