Mechanism and Machine Theory最新文献_第5页

Dynamic inversion and optimal tracking control on the ball-plate system based on a linearized nonholonomic multibody model 基于线性化非整体多体模型的球-板系统动态反转和优化跟踪控制

IF 4.5 1区工程技术

Mechanism and Machine Theory Pub Date : 2024-09-21 DOI: 10.1016/j.mechmachtheory.2024.105795

A.G. Agúndez , A. Saccon , D. García-Vallejo , E. Freire

{"title":"Dynamic inversion and optimal tracking control on the ball-plate system based on a linearized nonholonomic multibody model","authors":"A.G. Agúndez , A. Saccon , D. García-Vallejo , E. Freire","doi":"10.1016/j.mechmachtheory.2024.105795","DOIUrl":"10.1016/j.mechmachtheory.2024.105795","url":null,"abstract":"<div><div>This paper addresses the optimal control of the ball-plate system, a well-known nonholonomic system in the context of nonprehensile manipulation, using a multibody dynamics approach. The trajectory tracking control of a steady-state circular motion of the ball on the plate, for any radius and potentially off-centric with respect to the plate’s pivoting point, is achieved by designing a Linear-Quadratic Regulator. A spatial multibody model of the ball-plate system is considered. A key contribution is the analytical computation of the circular steady motion of the ball by dynamic inversion, including the control actions to achieve this reference solution. This enables the analytical computation of the linearized equations along this reference motion, resulting in a periodic linear time-varying (LTV) system, and the application of linear controllability criteria for LTV systems. A controllable linear system, involving the Cartesian coordinates of the contact point and the yaw angle of the sphere, is obtained using a convenient coordinate partition in the linearization. Compared to existing results on the same problem, closed-loop stability about the desired trajectory is achieved for any radius of the circular trajectory.</div></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"203 ","pages":"Article 105795"},"PeriodicalIF":4.5,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0094114X24002222/pdfft?md5=61cf4d5bbf6881351f1a0c8ae07724cd&pid=1-s2.0-S0094114X24002222-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Analytical determination of the optimal effective regular workspace of a 6-6 Stewart platform manipulator for a specified orientation workspace 分析确定指定方向工作空间的 6-6 斯图尔特平台机械手的最佳有效规则工作空间

IF 4.5 1区工程技术

Mechanism and Machine Theory Pub Date : 2024-09-20 DOI: 10.1016/j.mechmachtheory.2024.105791

Bibekananda Patra , Anirban Nag , Sandipan Bandyopadhyay

{"title":"Analytical determination of the optimal effective regular workspace of a 6-6 Stewart platform manipulator for a specified orientation workspace","authors":"Bibekananda Patra , Anirban Nag , Sandipan Bandyopadhyay","doi":"10.1016/j.mechmachtheory.2024.105791","DOIUrl":"10.1016/j.mechmachtheory.2024.105791","url":null,"abstract":"<div><div>This article presents an analytical method to identify the largest <em>effective regular workspaces</em> (ERWs) of a class of 6-6 Stewart platform manipulators for a given orientation workspace. The ERWs are modelled as spheres. The orientation workspace is specified in terms of ranges of Euler angles, as is the standard practice in the parallel robot industry. The radius of the said sphere is maximised through an optimisation problem, which is solved analytically. Consequently, the results obtained are <em>exact</em> in nature. The analytical formulation of the problem and its exact solutions constitute the novel theoretical contributions of this article. Moreover, since the results hold good over a given subset of <span><math><mrow><mi>SO</mi><mrow><mo>(</mo><mn>3</mn><mo>)</mo></mrow></mrow></math></span>, the proposed method obviates the need for numerical scanning of the orientation workspaces in design-related computations, thus improving the accuracy, robustness, as well as computational efficiency. Finally, the significance of the <em>neutral height</em> in harnessing the desired extents of position and orientation workspaces has been established through parametric studies. The formulations are illustrated via applications to Stewart platform manipulators of three distinct platform dimensions.</div></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"203 ","pages":"Article 105791"},"PeriodicalIF":4.5,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 new iterative identification algorithm for estimating the LuGre friction model parameters 用于估计鲁格莱摩擦模型参数的新迭代识别算法

IF 4.5 1区工程技术

Mechanism and Machine Theory Pub Date : 2024-09-19 DOI: 10.1016/j.mechmachtheory.2024.105797

Saeed Mahmoudkhani , Johnathan Gorenstein , Keivan Ahmadi

{"title":"A new iterative identification algorithm for estimating the LuGre friction model parameters","authors":"Saeed Mahmoudkhani , Johnathan Gorenstein , Keivan Ahmadi","doi":"10.1016/j.mechmachtheory.2024.105797","DOIUrl":"10.1016/j.mechmachtheory.2024.105797","url":null,"abstract":"<div><div>The parameters of dynamic friction models like the LuGre model are commonly identified by computationally intensive nonlinear optimization methods. In this paper, an alternative least-square-based iterative algorithm is proposed to simultaneously identify the LuGre model parameters and the inertial properties from a limited set of measurements. The LuGre model, expressed in two forms allowed independent identification of the static and dynamic parameters. Moreover, since the method uses response-input time–history instead of numerous constant velocity experiments (CVEs), both the inertial and friction parameters can be identified in much fewer experiments (theoretically one). A variant of the Sparse Identification of Nonlinear Dynamics method called SR3 is embedded in the algorithm to capture the nonlinear viscous friction and Stribeck effects in the friction model. Application of the algorithm to an industrial robot joint shows that the convergence of the algorithm is fast and the identified model is accurate in predicting the joint’s dynamics in a wide range of velocities. The friction-velocity curves resulting from the identified model are compared to those obtained by traditional CVEs to confirm the accuracy of the identified model.</div></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"203 ","pages":"Article 105797"},"PeriodicalIF":4.5,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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

Transient analysis of non-uniform tilting-pad journal bearing for wind turbine main shaft under dynamical loading 风力涡轮机主轴非均匀斜垫式轴颈轴承在动态载荷下的瞬态分析

IF 4.5 1区工程技术

Mechanism and Machine Theory Pub Date : 2024-09-19 DOI: 10.1016/j.mechmachtheory.2024.105792

Chaosheng Song, Ronghua Zhang, Ye Zhou, Jianjun Tan, Caichao Zhu

{"title":"Transient analysis of non-uniform tilting-pad journal bearing for wind turbine main shaft under dynamical loading","authors":"Chaosheng Song, Ronghua Zhang, Ye Zhou, Jianjun Tan, Caichao Zhu","doi":"10.1016/j.mechmachtheory.2024.105792","DOIUrl":"10.1016/j.mechmachtheory.2024.105792","url":null,"abstract":"<div><div>The non-uniform distributed tilting-pad journal bearing (NDTPJB), designed for large megawatt wind turbine main shafts, has not been assessed for transient stability under typical random wind conditions. Particularly, the dynamic interaction between low-speed, heavy-load operations with varying magnitude and direction, and the bearing's asymmetric structure, has not been fully explored. A new transient tribo-dynamic model is developed to analyze 6MW wind turbine's NDTPJB transient friction behavior, accounting for variable wind loads, pad distribution asymmetry, mixed lubrication (ML), and elastic pivot effects. Key parameters affecting tribo-dynamic friction performance—pad wrap angle, pad distribution count, and pivot stiffness—were comprehensively investigated. Findings show that dynamic loading cause asymmetrical behaviors in main and secondary pads, with performance significantly affected by the number of bottom distributed pads and improved stability with setting the number of above distributed pads to three. The stiffness of pivots significantly and complexly affects bearing dynamics, optimization of stiffness should be conducted after pad distribution determination. These discoveries guide further research and enhancements of NDTPJB in large rotating machinery under low-speed and heavy-load conditions.</div></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"203 ","pages":"Article 105792"},"PeriodicalIF":4.5,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 and optimization of a novel multi-layer conical Kresling origami mechanism (MCKOM) for linear actuation 设计和优化用于线性驱动的新型多层锥形克瑞斯林折纸机构 (MCKOM)

IF 4.5 1区工程技术

Mechanism and Machine Theory Pub Date : 2024-09-19 DOI: 10.1016/j.mechmachtheory.2024.105796

Cuiying Jiang , Decheng Wang , Peng Cheng , Lifang Qiu , Chongxiang Li

{"title":"Design and optimization of a novel multi-layer conical Kresling origami mechanism (MCKOM) for linear actuation","authors":"Cuiying Jiang , Decheng Wang , Peng Cheng , Lifang Qiu , Chongxiang Li","doi":"10.1016/j.mechmachtheory.2024.105796","DOIUrl":"10.1016/j.mechmachtheory.2024.105796","url":null,"abstract":"<div><p>To address the inevitable twisting issue of modular configurations with different morphological parameters, this paper takes conical Kresling units as the research object, and a novel multi-layer conical Kresling origami mechanism (MCKOM) for linear actuation is designed. The main body consists of <em>m</em> serially connected flat-foldable bistable units with the same chirality but different morphological parameters. The design objective of achieving pure linear actuation under torque drive is realized by introducing external systems. Kinematic coupling and inner product models are established and multi-objective optimization algorithms are employed to optimize the structure. Based on optimized values, simulation and experimental validation of the motion behavior are conducted using ABAQUS and prototypes. The results show that the total twist angle decreased by 10.076° and the inner product increased by 60,291.98 mm<sup>3</sup>. Furthermore, the crease vertices cutting eliminates the influence of internal pressure on the guiding plate's outward deviation and increases the folding ratio from 41.49 % to 48.88 % under experimental conditions. The proposed novel pure linear actuation mechanism can be applied in actuation scenarios that require the conversion of rotational motion into linear displacement.</p></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"203 ","pages":"Article 105796"},"PeriodicalIF":4.5,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142242980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 novel method of modelling contact dynamics for spur gear transmission 正齿轮传动接触动力学建模新方法

IF 4.5 1区工程技术

Mechanism and Machine Theory Pub Date : 2024-09-18 DOI: 10.1016/j.mechmachtheory.2024.105793

Lixin Xu , Yuankui Luo , Ruhao Hu

{"title":"A novel method of modelling contact dynamics for spur gear transmission","authors":"Lixin Xu , Yuankui Luo , Ruhao Hu","doi":"10.1016/j.mechmachtheory.2024.105793","DOIUrl":"10.1016/j.mechmachtheory.2024.105793","url":null,"abstract":"<div><p>Taking a pair of spur gears as the research object, a contact dynamic model of the spur gear system was established based on the theories of contact mechanics and multi-body dynamics. The characteristics of the model are such that it can describe the dynamic contact behavior of a gear pairs, the meshing action of gear pairs no longer depends on the stiffness model of single and double teeth undergoing alternating meshing, and the model can be visualized in real time. In the process of modelling, firstly, the mathematical model of spur gear is established. The spur gear dynamic model is then built. Finally, the vibration responses obtained by the three methods (the propose method, the lumped parameter method and the experimental method) are compared. It is found that the proposed method is more consistent with the experimental method than the traditional lumped parameter method, which verifies the validity of the contact dynamic model of spur gear transmission. The proposed model and research results lay the foundation for research fields such as performance analysis, design optimization and fault diagnosis of gear systems.</p></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"203 ","pages":"Article 105793"},"PeriodicalIF":4.5,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142242970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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

Numerical study on the effectiveness of the optimization of the load distribution in ball screw actuators 滚珠丝杠推杆载荷分布优化效果的数值研究

IF 4.5 1区工程技术

Mechanism and Machine Theory Pub Date : 2024-09-16 DOI: 10.1016/j.mechmachtheory.2024.105781

L. Sangalli, A. Oyanguren, M. Izquierdo, J. Larrañaga, I. Ulacia

{"title":"Numerical study on the effectiveness of the optimization of the load distribution in ball screw actuators","authors":"L. Sangalli, A. Oyanguren, M. Izquierdo, J. Larrañaga, I. Ulacia","doi":"10.1016/j.mechmachtheory.2024.105781","DOIUrl":"10.1016/j.mechmachtheory.2024.105781","url":null,"abstract":"<div><p>Load distribution in ball screws is characterized by non-uniformity, leading to imbalances in the contact load of the balls along the nut. This non-uniformity negatively impacts the stiffness, accuracy and service life of the ball screw. This work proposes a solution to reduce the ball screw load distribution non-uniformity through an optimization model and two implementation methods: the variable pitch method and the ball offset method. Both methods involve applying an initial preload in certain areas of the nut to compensate for load imbalance. A case study tests both methods and evaluates the implications of implementing the optimization model.</p><p>Results confirm the model’s ability to reduce the load distribution non-uniformity, with a ratio improvements up to 61%. Additionally, this optimization enhances stiffness by up to 78% and extends service life by up to 17 times. The study also identifies the model’s limits and possible adverse effects, concluding that the specific case conditions must be considered in the optimization process.</p></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"203 ","pages":"Article 105781"},"PeriodicalIF":4.5,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142242979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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

Optimization design and key-term separation identification of parallel six-dimensional pose sensor with high sensitivity and high precision 高灵敏度和高精度并行六维姿态传感器的优化设计和关键项分离识别

IF 4.5 1区工程技术

Mechanism and Machine Theory Pub Date : 2024-09-13 DOI: 10.1016/j.mechmachtheory.2024.105716

Jianfeng Lin , Chenkun Qi , Yan Hu , Feng Gao

{"title":"Optimization design and key-term separation identification of parallel six-dimensional pose sensor with high sensitivity and high precision","authors":"Jianfeng Lin , Chenkun Qi , Yan Hu , Feng Gao","doi":"10.1016/j.mechmachtheory.2024.105716","DOIUrl":"10.1016/j.mechmachtheory.2024.105716","url":null,"abstract":"<div><p>The integrated bearing-positioning parallel manipulator is an important mean for ground testing of space optical telescope before being launched into space. To ensure positioning accuracy, the manipulator requires a pose sensor for the end-effector measurement with six degrees of freedom (DOF), real-time, high-precision, and operation in a vacuum environment. However, it is challenging for the current pose sensor to simultaneously meet all these requirements. In this paper, a novel concept of six-dimensional pose sensor based on parallel mechanism is proposed. A new mechanism design approach is presented to achieve the large measurement range, real-time measurement performance, and high accuracy measurement based on performance atlas. First, the G<sub>F</sub> sets synthesis is developed to optimize the configuration of pose sensor. Next, two new design indicators are proposed to evaluate the real-time and high accuracy performance. Mechanism parameters are optimized by combining with mechanism singularity analysis. To guarantee high measurement accuracy, a key-term separation identification method with double neural networks is presented. Experiments on 6-UPS pose sensor demonstrate the effectiveness of the proposed mechanism design and key-term identification approach.</p></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"203 ","pages":"Article 105716"},"PeriodicalIF":4.5,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142171897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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

Fast mobility analysis for generative design applications through a real vector space representation of mobilities 通过移动性的真实向量空间表示，为生成式设计应用提供快速移动性分析

IF 4.5 1区工程技术

Mechanism and Machine Theory Pub Date : 2024-09-11 DOI: 10.1016/j.mechmachtheory.2024.105790

Guilain Lang , Julien Rouvinet

{"title":"Fast mobility analysis for generative design applications through a real vector space representation of mobilities","authors":"Guilain Lang , Julien Rouvinet","doi":"10.1016/j.mechmachtheory.2024.105790","DOIUrl":"10.1016/j.mechmachtheory.2024.105790","url":null,"abstract":"<div><p>During the early stages of design, mechanisms are commonly modeled as perfect joints assembled with infinitely rigid bodies. This representation enables the prediction of the system’s mobilities through a mobility analysis. However, traditional mobility analysis tools can be computationally expensive or lack critical information, such as the type or direction of mobilities. It hinders the generation of topology and configuration through generative design schemes.</p><p>In this paper, we propose an alternative approach to mobility analysis based on a real vector space representation of mobilities. Our method provides relevant information for early design steps while being computationally effective through a novel formulation of series and parallel assembly topological operations. A benchmark on four selected use cases highlights an acceleration of 3 to 4 orders of magnitude compared to traditional approaches. Additionally, design rules on the joints’ positions can be automatically generated with our approach. It enables the automation of the complete design process, including topology and configuration. As such, we provide guidelines to develop a generative design scheme dedicated to the synthesis of guiding mechanisms.</p></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"203 ","pages":"Article 105790"},"PeriodicalIF":4.5,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0094114X24002179/pdfft?md5=707d548a4597f571ad66ed948b72d5ec&pid=1-s2.0-S0094114X24002179-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142168575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Computerized generation, deviation correction and rapid tooth contact analysis of helical face gear 螺旋齿面齿轮的计算机生成、偏差修正和快速齿面接触分析

IF 4.5 1区工程技术

Mechanism and Machine Theory Pub Date : 2024-09-10 DOI: 10.1016/j.mechmachtheory.2024.105789

Yaolong Yan , Hui Guo , Jun Gu , Ning Zhao , Li Liu

{"title":"Computerized generation, deviation correction and rapid tooth contact analysis of helical face gear","authors":"Yaolong Yan , Hui Guo , Jun Gu , Ning Zhao , Li Liu","doi":"10.1016/j.mechmachtheory.2024.105789","DOIUrl":"10.1016/j.mechmachtheory.2024.105789","url":null,"abstract":"<div><p>This paper delves into the generation of helical face gears using a grinding worm. It investigates the computerized generation process and explores the inherent geometric constraints associated with the application of a grinding worm for helical face gears. An approximate grinding method, tailored for helical face gears featuring large helix angles, is proposed, with an evaluation of the resulting theoretical deviations. Furthermore, a novel rapid computational approach for determining the bearing contact of helical face gear pairs is introduced and validated through Finite Element Analysis (FEA). The subsequent analysis comprehensively examines the effects of the machine tool positioning errors on tooth flank deviations, bearing contact, and transmission errors. A sensitivity matrix is developed to elucidate the relationship between machine tool positioning errors and the tooth flank deviations, leading to the proposition of a correction method for theoretical generating deviations. Finally, the paper introduces a tooth flank modification method for helical face gears and the meshing performance is highly improved.</p></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"203 ","pages":"Article 105789"},"PeriodicalIF":4.5,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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