Marine Structures最新文献_第5页

A statistic-based tracking method of equivalent constraint position for monopile supported offshore wind turbine 基于统计的单桩支撑海上风力涡轮机等效约束位置跟踪方法

IF 4 2区工程技术

Marine Structures Pub Date : 2024-07-13 DOI: 10.1016/j.marstruc.2024.103673

Shuang Chang , Qiang Liu , Zhixin Zhao , Fushun Liu

{"title":"A statistic-based tracking method of equivalent constraint position for monopile supported offshore wind turbine","authors":"Shuang Chang , Qiang Liu , Zhixin Zhao , Fushun Liu","doi":"10.1016/j.marstruc.2024.103673","DOIUrl":"https://doi.org/10.1016/j.marstruc.2024.103673","url":null,"abstract":"<div><p>Bearing capacity of pile foundation is one of the important factors affecting the safe operation of the offshore wind turbines. However, due to the influence of different geological conditions, pile types and other factors, it is difficult for the existing monitoring methods to obtain the change of real constraints of the pile foundation. A statistic-based equivalent constraint position prediction method for offshore wind turbines is proposed. The method is based on the first-order displacement and first-order frequency extracting from the measured acceleration signals obtained by the accelerometers installed above the water surface, and statistical method is adopted to eliminate the influence of noise and reduce the error caused by single prediction. The most achievement of the proposed method is that the constraint of pile foundation related to bearing capacity is obtained and quantified by equivalent constraint position, and more accurate assessment of safety state of the offshore wind turbine can be achieved. To verify the reliability of proposed method, numerical model of a 4-MW monopile supported offshore wind turbine considering the pile–soil interaction is carried out. The results show that the proposed method can accurately obtain the equivalent constraint position by a combination of first-order frequency and first-order displacement. Further, the field measurement of an offshore wind turbine located in Rudong County, Jiangsu Province of China is performed. A stable prediction of equivalent constraint range from -30.86 m to -30.15 m is obtained over 43 days of the test. Therefore, the proposed method can be used to predict the change of pile foundation constraint, and is of great significance to the safety assessment of offshore wind turbines.</p></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"98 ","pages":"Article 103673"},"PeriodicalIF":4.0,"publicationDate":"2024-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141605074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A study for the bending vibration analysis of the intermittently welded stiffened plate 间歇焊接加劲板的弯曲振动分析研究

IF 4 2区工程技术

Marine Structures Pub Date : 2024-07-13 DOI: 10.1016/j.marstruc.2024.103674

Yong-Ho Ri, Un-Ryong Rim, Ji-Song Mun

{"title":"A study for the bending vibration analysis of the intermittently welded stiffened plate","authors":"Yong-Ho Ri, Un-Ryong Rim, Ji-Song Mun","doi":"10.1016/j.marstruc.2024.103674","DOIUrl":"https://doi.org/10.1016/j.marstruc.2024.103674","url":null,"abstract":"<div><p>A simplified analytical method for analyzing the dynamic behavior of the intermittently welded stiffened plate is newly proposed.</p><p>The plate and stiffener are considered as individual beams, and the influence of the longitudinal internal shear force per unit length at the stiffener-to-plate junction of a continuously welded stiffened plate is considered. The whole span of an intermittently welded stiffened plate is divided into welded and non-welded segments. The intermittently welded stiffened plate is changed into equivalent continuously welded one, and a model for the bending vibration analysis of the intermittently welded stiffened plate is developed. The governing equation for the bending vibration analysis of the intermittently welded stiffened plate by the influence function method is formulated and a practical approach is newly developed to solve the governing equation for the bending vibration analysis of the intermittently welded stiffened plate. The numerical calculation for bending vibration analysis of the intermittently welded stiffened plate is carried out. A comparison of results from the proposed method with the finite element analysis results is carried out to demonstrate the validity of the proposed method.</p></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"98 ","pages":"Article 103674"},"PeriodicalIF":4.0,"publicationDate":"2024-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141605073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Investigation on the coupling damage effects of ships subjected to near-field underwater explosion loads 船舶在近场水下爆炸荷载作用下的耦合损伤效应研究

IF 4 2区工程技术

Marine Structures Pub Date : 2024-07-10 DOI: 10.1016/j.marstruc.2024.103664

Ruiyuan Huang , Yipeng Jiang , Jian Qin , Xiangyao Meng , Hui Chi , Xiaoqiang Yang , Xianhui Zheng , Zhichao Lai

{"title":"Investigation on the coupling damage effects of ships subjected to near-field underwater explosion loads","authors":"Ruiyuan Huang , Yipeng Jiang , Jian Qin , Xiangyao Meng , Hui Chi , Xiaoqiang Yang , Xianhui Zheng , Zhichao Lai","doi":"10.1016/j.marstruc.2024.103664","DOIUrl":"https://doi.org/10.1016/j.marstruc.2024.103664","url":null,"abstract":"<div><p>Near-field underwater explosions generate complex load forms and cause destructive strikes on ships. To investigate the damage characteristics of ships under the combined effect of multiple loads, local and overall damage modes were first investigated through the combination of experimental tests and numerical simulation. Then a series of numerical simulations of full-scale ships subjected to near-field underwater explosions with different stand-off distances, equivalents, and detonation positions were carried out. The damage effects of shock wave, bubble pulsation, after flow, and water jet loads on ships were analyzed. The results show that the combined effects of different loads lead to different damage modes. Shock waves and after flow loads are the main cause of local damage and hogging damage, while pressure difference and bubble adsorption are the main reasons for the hogging damage. Finally, a criterion was proposed to determine the damage modes of ships under near-field underwater explosions.</p></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"98 ","pages":"Article 103664"},"PeriodicalIF":4.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141582124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effects of cyclic ageing frequencies on the ageing and mechanical behaviour of adhesive materials: Experimental analysis and numerical study 循环老化频率对粘合剂材料老化和机械性能的影响：实验分析和数值研究

IF 4 2区工程技术

Marine Structures Pub Date : 2024-07-08 DOI: 10.1016/j.marstruc.2024.103662

M. Moazzami , A. Akhavan-Safar , M.R. Ayatollahi , Johannes.A. Poulis , L.F.M. da Silva , S. Teixeira De Freitas

{"title":"Effects of cyclic ageing frequencies on the ageing and mechanical behaviour of adhesive materials: Experimental analysis and numerical study","authors":"M. Moazzami , A. Akhavan-Safar , M.R. Ayatollahi , Johannes.A. Poulis , L.F.M. da Silva , S. Teixeira De Freitas","doi":"10.1016/j.marstruc.2024.103662","DOIUrl":"https://doi.org/10.1016/j.marstruc.2024.103662","url":null,"abstract":"<div><p>In marine structures adhesive joint structures are often exposed to cyclic conditioning where the ambient humidity changes cyclically during their service. Though some comprehensive studies on the aging of adhesives exist, these researches mainly focus on monotonic aging conditions where the adhesive joints are exposed to a wet condition continuously for a long time. However, the few investigations performed on the cyclic moisture absorption of adhesive materials show that the parameters obtained in monotonic aging conditions are not suitable for estimation of the aging behaviour of adhesive exposed to alternating humidity. An important question that can arise is whether or not this frequency affects the mechanical behaviour of adhesive joints under cyclic aging condition. In this investigation bulk dogbone and square samples were manufactured, subjected to cyclic aging conditions with four different aging frequencies and tested. The results show that the moisture diffusion constant of adhesives exposed to higher aging frequencies increase more than those exposed to lower aging frequency conditions. In addition, the moisture content only affects the degradation of strength and stiffness of the tested adhesives in different aging frequencies.</p></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"98 ","pages":"Article 103662"},"PeriodicalIF":4.0,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141582340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Modelling of foundation damping in time-domain analysis of monopile supported offshore wind turbine structures 单桩支撑海上风力涡轮机结构时域分析中的地基阻尼建模

IF 4 2区工程技术

Marine Structures Pub Date : 2024-07-08 DOI: 10.1016/j.marstruc.2024.103672

Peng Guo , Haowei Ling , Youhu Zhang , Tongyu Di

{"title":"Modelling of foundation damping in time-domain analysis of monopile supported offshore wind turbine structures","authors":"Peng Guo , Haowei Ling , Youhu Zhang , Tongyu Di","doi":"10.1016/j.marstruc.2024.103672","DOIUrl":"https://doi.org/10.1016/j.marstruc.2024.103672","url":null,"abstract":"<div><p>Foundation damping holds large potential for design optimisations of monopile-supported offshore wind turbine structures. However, the contribution of foundation damping is not well understood, in part due to lack of suitable method for incorporating foundation damping in the time-domain analysis of wind turbine structures. This paper presents a practical approach for this purpose in which a dashpot is attached in parallel to each <em>p</em>-<em>y</em> spring along the monopile. In this way, the distributed soil-pile interaction stiffness and damping are accurately modelled. To demonstrate the validity of the proposed approach, a case study exploring the influence of foundation damping on the dynamic response of an IEA 15 MW reference turbine founded on monopile is carried out. The results demonstrate that the foundation damping has relatively limited impact on the overall dynamic response and fatigue loads in power production states. However, inclusion of foundation damping is shown to significantly reduce the structural response after emergency shutdown and under parked conditions. The findings of the case study show promising potential for wind turbine structure design optimization through consideration of foundation damping.</p></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"98 ","pages":"Article 103672"},"PeriodicalIF":4.0,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141582341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Design, construction and testing of a fully elastic ship model for investigating hydro-elastic responses of container ships 设计、建造和测试用于研究集装箱船水弹性响应的全弹性船舶模型

IF 4 2区工程技术

Marine Structures Pub Date : 2024-07-08 DOI: 10.1016/j.marstruc.2024.103663

Yingying Chen, Shanli Zhang, Wei Kean Chen, Allan Magee

{"title":"Design, construction and testing of a fully elastic ship model for investigating hydro-elastic responses of container ships","authors":"Yingying Chen, Shanli Zhang, Wei Kean Chen, Allan Magee","doi":"10.1016/j.marstruc.2024.103663","DOIUrl":"https://doi.org/10.1016/j.marstruc.2024.103663","url":null,"abstract":"<div><p>Models used in hydro-elastic experiments should not only reflect the geometries of the hull form, but also the elastic characteristics of the prototype. Two types of models have been generally developed for this purpose: segmented and fully elastic models. When scaling sectional properties, most studies have only considered similarity in the vertical bending mode. Container ships may also experience high torsional moments in addition to vertical bending moments, because of their large openings on the deck. To investigate the various hydro-elastic response of container ships, we develop and present a fully elastic ship-shape model in this study. Applying a novel structural design with internal structures resembling a container ship allows the vertical bending, horizontal bending and torsional vibration modes to be similar to those of a prototype container ship. Strain gauges instrumented throughout the model measure the hydro-elastic structural response including vertical bending moment, vertical shear force, and torsional moment. We studied the elastic parameters of the model comprehensively through a series of experiments and further tested the model in different wave conditions and forward speeds through wave experiments. We found the measured global structural responses agree with those of numerical simulations. The methodologies developed in this study provide new insights into how to design a fully elastic model which can be used to investigate the hydro-elastic responses of container ships.</p></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"98 ","pages":"Article 103663"},"PeriodicalIF":4.0,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141582122","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

An improved scaled model design method for box girders under hogging moment considering the ultimate bending moment and collapse modes 考虑极限弯矩和坍塌模式的曳引力矩下箱梁改进比例模型设计方法

IF 4 2区工程技术

Marine Structures Pub Date : 2024-07-03 DOI: 10.1016/j.marstruc.2024.103660

Hongyang Ma , Yasumi Kawamura , Tetsuo Okada , Deyu Wang , Ginga Hayakawa

{"title":"An improved scaled model design method for box girders under hogging moment considering the ultimate bending moment and collapse modes","authors":"Hongyang Ma , Yasumi Kawamura , Tetsuo Okada , Deyu Wang , Ginga Hayakawa","doi":"10.1016/j.marstruc.2024.103660","DOIUrl":"10.1016/j.marstruc.2024.103660","url":null,"abstract":"<div><p>An improved scaled method for box girders subjected to a hogging moment is developed based on maintaining the similarity of section properties and slenderness. The section area, moment of inertia, section modulus, plate slenderness, and column slenderness are considered as factors influencing the determination of the ultimate hogging moment. A smaller scale ratio is required to reduce the load-carrying capacity of scaled models, which poses challenges in ensuring that the designed scaled model aligns with the requirements of the construction process. Based on the discussion of several design strategies, a reasonable design of scaled models can be achieved through the following steps. First, the similarity of the plate slenderness is maintained by adjusting the number of stiffeners. Secondly, the similarity in column slenderness is maintained by adjusting the plate length. Third, the similarity of the section properties is improved by maintaining the similarity of the area of the local part. Simultaneously, the scaling strategy of the stiffeners is changed to ensure the similarity of the collapse modes. Fourth, modification methods for the similarity of the moment of inertia and section modulus are proposed to further improve the similarity of the ultimate bending moment. Furthermore, the criteria for choosing a modification of the section modulus and moment of inertia were proposed.</p></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"98 ","pages":"Article 103660"},"PeriodicalIF":4.0,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141547546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Analysis of safety and impact probability of subsea Christmas tree impacted by falling objects 水下圣诞树受坠落物体撞击的安全性和撞击概率分析

IF 4 2区工程技术

Marine Structures Pub Date : 2024-06-29 DOI: 10.1016/j.marstruc.2024.103655

Nan Pang , Xiangyu Wang , Zhuang Liu , Kai Xu , Zhong Liu , Zhonggang Xiong , Chao Li

{"title":"Analysis of safety and impact probability of subsea Christmas tree impacted by falling objects","authors":"Nan Pang , Xiangyu Wang , Zhuang Liu , Kai Xu , Zhong Liu , Zhonggang Xiong , Chao Li","doi":"10.1016/j.marstruc.2024.103655","DOIUrl":"https://doi.org/10.1016/j.marstruc.2024.103655","url":null,"abstract":"<div><p>At present, there is no clear data to analyze the probability and impact of falling objects on the subsea Christmas tree. However, during the long-term operation in the complex deep-sea environment, objects may fall and hit the tree due to the anchored platform, fishing boat operation or other reasons, the impact of large heavy objects onto the tree can potentially give rise to the development of internal forces higher than those for which the tree was designed to. Therefore, aiming at the risk problem of falling objects, the paper presents the development process and results of an improved impact probability numerical method. And the safety model of falling object impact on the tree is established. Preliminary results indicate that the method offers valuable insight including and beyond a probability estimation of third-party damage, and the safety results were obtained. At the same time, the influencing factors of the tree impacted by falling objects are analyzed, and the serious influencing factors are obtained, which provides theoretical basis for the design and optimization of the protection frame of subsea square equipment.</p></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"97 ","pages":"Article 103655"},"PeriodicalIF":4.0,"publicationDate":"2024-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141484792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Nonlinear behavior analysis of smooth bore unbonded flexible pipes under radial compression 光滑内孔无粘结柔性管道在径向压缩下的非线性行为分析

IF 4 2区工程技术

Marine Structures Pub Date : 2024-06-27 DOI: 10.1016/j.marstruc.2024.103661

Shanghua Wu , Shichao Wang , Qingzhen Lu , Zhixun Yang , Tao Zhang , Yuanchao Yin , Jun Yan

{"title":"Nonlinear behavior analysis of smooth bore unbonded flexible pipes under radial compression","authors":"Shanghua Wu , Shichao Wang , Qingzhen Lu , Zhixun Yang , Tao Zhang , Yuanchao Yin , Jun Yan","doi":"10.1016/j.marstruc.2024.103661","DOIUrl":"https://doi.org/10.1016/j.marstruc.2024.103661","url":null,"abstract":"<div><p>Smooth bore unbonded flexible pipes are widely used to transport oil and gas in offshore fields. Due to its main application in shallow water, the radial bearing capacity is usually designed to be low for economic reasons. If the compressive load applied by tensioner equipment is too high during installation, the flexible pipe will fail due to excessive deformation. In this paper, the nonlinear behavior of smooth bore flexible pipes passing through tensioner equipment was investigated numerically and experimentally. A three-dimensional numerical model considering the nonlinear behavior of the materials, layer-to-layer contacts, and friction for flexible pipe radial compression analysis was established. A radial compression test was conducted to verify the accuracy of the numerical model; Then the numerical model was used to analyze the radial compressive behavior of each layer, and its load-bearing capacities and failure mechanisms were investigated. Finally, a parametric study was performed on the opening angle and number of tensioner tracks. The results of this study can provide a useful reference for the installation of smooth bore flexible pipes.</p></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"97 ","pages":"Article 103661"},"PeriodicalIF":4.0,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141484791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A hydroelastic optimization method for multiseparated modules of floating composite structures in two-dimension 二维浮动复合结构多分离模块的水弹性优化方法

IF 4 2区工程技术

Marine Structures Pub Date : 2024-06-21 DOI: 10.1016/j.marstruc.2024.103658

Hui Fang, Yuxin Chen, Guoheng Xing, Aijun Li, Yong Liu

{"title":"A hydroelastic optimization method for multiseparated modules of floating composite structures in two-dimension","authors":"Hui Fang, Yuxin Chen, Guoheng Xing, Aijun Li, Yong Liu","doi":"10.1016/j.marstruc.2024.103658","DOIUrl":"https://doi.org/10.1016/j.marstruc.2024.103658","url":null,"abstract":"<div><p>This study proposes a hydroelastic optimization method for multiseparated modules of high-specific-strength floating structures with low-weight cores and high-strength surfaces in two-dimension. A sixth-order dynamical model of this floating composite structure is deduced from the fluid-structure interaction condition of the wave surface. Drawing upon potential flow theory and separation of variables, we discretize the water domain into plate-covered areas and open water areas, in which the analytical solution for the interaction between waves and the floating composite structure with any number of separated modules is derived. The convergence and accuracy of the analytical solution are verified by calculating the transmission and reflection coefficients of the waves and various hydrodynamic parameters, including deflection, bending moment, and shear force. Furthermore, the effects of the number of modules, module spacing, and core thickness on the hydrodynamic parameters of the floating structure are investigated. The module number and structural-component-material parameters are coupled in influencing the hydroelastic behavior and mechanical responses of this floating cluster. This proposed method is an alternative optimization technique for considering the sea state, spatial modules, structural features and material properties in practical engineering applications.</p></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"97 ","pages":"Article 103658"},"PeriodicalIF":4.0,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141438324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0