Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics最新文献_第6页

Efficient swimming through electroactive polymer hydrodynamic sensing 高效游泳通过电活性聚合物流体动力学传感

Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics Pub Date : 2023-04-28 DOI: 10.1117/12.2658203

A. Bruns, Antony Tang, M. H. Mahmoudinezhad, N. Jayaneththi, S. Rosset, Iain A. Anderson

{"title":"Efficient swimming through electroactive polymer hydrodynamic sensing","authors":"A. Bruns, Antony Tang, M. H. Mahmoudinezhad, N. Jayaneththi, S. Rosset, Iain A. Anderson","doi":"10.1117/12.2658203","DOIUrl":"https://doi.org/10.1117/12.2658203","url":null,"abstract":"For long-range swimming fish, low cost of transportation is a critical requirement. This also applies to autonomous fishlike robots (AFR). As with their biological cohorts, AFR require sensory input that characterizes the flow of the water surrounding them. Thus, there is a need for low power hydrodynamic sensors that can be deployed on a fish-like robot, and which can provide flow information from open water conditions. Electroactive polymers offer opportunities for flow sensing on soft and flexible AFR. We developed and evaluated an approach for capacitive electroactive polymer flow sensing. This uses dielectric elastomer sensor membranes mounted on a liquid-filled cavity protruding into the flow. Flow speed and incident angle on a hydrofoil standing in for the fish are registered through electrical capacitance changes resulting from deformation of its 350μm thick membrane. Through its triple-electrode design, measurements are largely shielded against the influence of the surrounding water on the capacitor. Differences in flow speed along the sensor can be detected with high reproducibility for extended durations of time. The developed sensors were assessed regarding accuracy, reliability, and durability. For performance and long-term testing, an automated tabletop water tunnel test rig was created. This setup enables sensor testing for flows up to 1 m/s with automated incident angle control and data logging. We are thus presenting further steps towards robust ocean-faring hydrodynamic sensory systems by demonstrating advances in electroactive sensory technology and testing facilities.","PeriodicalId":89272,"journal":{"name":"Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics","volume":"15 1","pages":"124820C - 124820C-9"},"PeriodicalIF":0.0,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80137238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Structural modal parameter identification incorporating with semi-active piezoelectric control 结合半主动压电控制的结构模态参数辨识

Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics Pub Date : 2023-04-28 DOI: 10.1117/12.2656930

Y. Hara, H. Asanuma, Keisuke Otsuka, Kanjuro Makihara

{"title":"Structural modal parameter identification incorporating with semi-active piezoelectric control","authors":"Y. Hara, H. Asanuma, Keisuke Otsuka, Kanjuro Makihara","doi":"10.1117/12.2656930","DOIUrl":"https://doi.org/10.1117/12.2656930","url":null,"abstract":"In this paper, we present a novel structural identification method using semi-active inputs generated by piezoelectric transducers. Structural identification using input and output information provides an accurate structural model. Conventional identification uses a maximum-length sequence, whose signal shape is similar to a square wave, as input. To generate inputs suitable for identification, several devices are required. These devices consume a lot of energy. If inputs are generated by a small number and simple design devices with low consumption, structural identification will be more practical. Piezoelectric semi-active control has been used in the research field of vibration control. This control generates a semi-active input whose signal shape is similar to a square wave. The semi-active input is generated by a simple circuit. The generation of the semi-active input consumes little energy. Therefore, the semi-active input has the potential to be used as an identification input instead of the maximum-length sequence. The property of the semi-active input is related to the generation strategy. This paper proposes a novel strategy to generate a semi-active input suitable for identification. Due to the unique mechanism of semi-active input generation, the novel strategy sometimes has the problem of generating semi-active inputs that are not suitable for identification. This paper discusses the reason and the solution to this problem. The feasibility of semi-active identification is presented through the numerical simulation and validation experiment. The identification result of the proposed method was close to the exact model. The proposed method achieved a 99% reduction in energy consumption.","PeriodicalId":89272,"journal":{"name":"Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics","volume":"18 1","pages":"124830H - 124830H-15"},"PeriodicalIF":0.0,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90680735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Smart acoustic lining for UHBR technologies engine: from the design of an electroacoustic metasurface to experimental characterization under flow UHBR技术引擎的智能声学衬里:从电声超表面的设计到流动下的实验表征

Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics Pub Date : 2023-04-28 DOI: 10.1117/12.2658519

K. Billon, Martin Gillet, E. Salze, M. Volery, E. De Bono, M. Ouisse, Hervé Lissek, M. Collet, J. Mardjono

{"title":"Smart acoustic lining for UHBR technologies engine: from the design of an electroacoustic metasurface to experimental characterization under flow","authors":"K. Billon, Martin Gillet, E. Salze, M. Volery, E. De Bono, M. Ouisse, Hervé Lissek, M. Collet, J. Mardjono","doi":"10.1117/12.2658519","DOIUrl":"https://doi.org/10.1117/12.2658519","url":null,"abstract":"The SALUTE project aims at evaluating performance of electroacoustic metasurface, employing a surface array of controlled electroacoustic actuators, for smart acoustic lining under grazing turbulent flow to be used in UHBR Technologies Engines. Theoretical and numerical investigations have been carried out for designing innovative concepts for complex aero-acoustic characterization in an engine mock-up. A specific focus was placed in the realization of prototypes for evaluating the metacomposite liner performances in 3D liners close to real engine implementation, its process complexity and robustness. This project provides new tools for designing smart acoustic liners; while acoustical experimental tests demonstrate efficiency and robustness of such technology for controlling UHBR noise emission. This paper presents the concept development from theory to technological realization and characterization by produced numerical tools. The experimental results obtained with the liners in acoustic flow duct facilities (FDF) have been realized in the PHARE facilities of Ecole Centrale de Lyon. Different configurations of liners have been tested using similar flow conditions as in target engine: 1 passive liner used as reference and a 3D active liner based on an array of electroacoustic absorbers. The final tests campaign comprises acoustics and aerodynamics measurements to characterize the aeroacoustics flow conditions, the membrane behavior, the achieved synthetic acoustic impedance and the resulting insertion loss.","PeriodicalId":89272,"journal":{"name":"Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics","volume":"12483 1","pages":"1248319 - 1248319-7"},"PeriodicalIF":0.0,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87086876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Investigation of the pre-stretch-dependent stability and force output of carbon-fiber-reinforced dielectric elastomer actuators 碳纤维增强介电弹性体作动器的预拉伸稳定性及力输出研究

Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics Pub Date : 2023-04-28 DOI: 10.1117/12.2656920

Anett Endesfelder, Markus Koenigsdorff, J. Mersch, Moritz Ullmann, M. Zimmermann, G. Gerlach

{"title":"Investigation of the pre-stretch-dependent stability and force output of carbon-fiber-reinforced dielectric elastomer actuators","authors":"Anett Endesfelder, Markus Koenigsdorff, J. Mersch, Moritz Ullmann, M. Zimmermann, G. Gerlach","doi":"10.1117/12.2656920","DOIUrl":"https://doi.org/10.1117/12.2656920","url":null,"abstract":"Dielectric elastomer actuators (DEAs) have advantageous characteristics and, therefore, their application is widespread in the field of soft robotics. Their properties can be specifically adapted by both the selection of materials and the manufacturing process. Previous research has shown that fiber reinforcement of the structure can significantly enhance the unidirectional motion. In the presented work an actuator consisting of a silicone film as the dielectric, a textile carbon-fiber-reinforced electrode and a carbon black electrode are used. The electrode based on the carbon fibers additionally serves as unidirectional stiffener. Due to this highly anisotropic textile electrode, the DEA barely contracts in fiber direction. However, the active force of the DEA during actuation can be further increased through an initial pre-stretching. The aim of this work is to investigate the influence of the pre-stretching in fiber direction on the actuator performance and the long-term stability of the pre-stretch. The active force of different actuators is recorded with uniaxial tensile tests over several deformation cycles. This enables the investigation of effects deriving both from the manufacturing process and the layer structure of the textile DEA. The acquired data are evaluated and compared to results of an analytical model. To explore the ability of the fibers to maintain the initial pre-stretching of the DEA during activation, digital image correlation as an in-situ imaging technique is applied. It could be shown shown that there is no change in width due to the anisotropy. The results of the investigations are used to control and improve the manufacturing process of the textile DEA.","PeriodicalId":89272,"journal":{"name":"Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics","volume":"29 1","pages":"124820O - 124820O-9"},"PeriodicalIF":0.0,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86952392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Theoretical investigation of bistable piezoelectric energy harvester using frequency down-conversion 变频双稳压电能量采集器的理论研究

Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics Pub Date : 2023-04-28 DOI: 10.1117/12.2657605

Hadeel Abumarar, Alwathiqbellah Ibrahim, A. Ramini

{"title":"Theoretical investigation of bistable piezoelectric energy harvester using frequency down-conversion","authors":"Hadeel Abumarar, Alwathiqbellah Ibrahim, A. Ramini","doi":"10.1117/12.2657605","DOIUrl":"https://doi.org/10.1117/12.2657605","url":null,"abstract":"Recently, vibrational energy harvesting has been considered a promising alternative to batteries for powering microsystems for large wireless sensor network applications. However, ambient vibrations are below 100 Hz, while most machines and equipment operate relatively at high frequencies (more than 70 Hz). Herein, we propose a theoretical study to harvest energy from high frequencies using a frequency-down bistable piezoelectric energy harvester mechanism. We investigate the energy harvesting benefit in the down-conversion of a high-frequency signal to a low-frequency signal utilizing magnetic coupling. A high-frequency driving beam triggers a low-frequency generating beam. We use a spring-mass-damper equivalent model to understand the operation mechanism of the proposed piezoelectric vibration energy harvester. Based on the theoretical model, the static and dynamic effect of magnetic nonlinearity on the performance of the proposed piezoelectric vibration energy harvester is numerically analyzed. The targeted applications are the down-conversion and the filtering of high frequencies and mass sensing, particularly the harvester’s behavior for mass sensing applications.","PeriodicalId":89272,"journal":{"name":"Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics","volume":"19 1","pages":"124830T - 124830T-15"},"PeriodicalIF":0.0,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89912183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Acceleration-waveform-sending wireless sensor node powered by piezoelectric vibration energy harvester 由压电振动能量采集器驱动的加速度波形发送无线传感器节点

Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics Pub Date : 2023-04-28 DOI: 10.1117/12.2657742

T. Yamada, H. Asanuma, Y. Hara, A. Erturk

{"title":"Acceleration-waveform-sending wireless sensor node powered by piezoelectric vibration energy harvester","authors":"T. Yamada, H. Asanuma, Y. Hara, A. Erturk","doi":"10.1117/12.2657742","DOIUrl":"https://doi.org/10.1117/12.2657742","url":null,"abstract":"We have developed a wireless sensor node (WSN) powered by a piezoelectric vibration energy harvester that enables transmission of three-axis acceleration waveform data. Unlike a conventional WSN, which sends a single point representing the root mean square acceleration value, the proposed WSN allows the frequency, vibrational modes, and displacement of the target structure to be obtained. Therefore, this waveform-sending scenario is highly suitable for structural health monitoring applications. We used a power gating technique to reduce the standby energy consumption significantly and thus realize the waveform-sending concept. The overall dimensions and mass of the WSN are 3×3×3 cm3 and 26 g, respectively. The overall dimensions of the harvester are 5.6×2×2.1 cm3. The WSN measures the threeaxis acceleration of the structure’s vibration for 1.2 s at a sampling rate of 3,200 samples every 5 min, transmits the data, and then goes into standby mode. Because of the power gating technique, the energy consumption per cycle is as low as 108 mJ. We evaluated the WSN under both harmonic and random vibration conditions. For harmonic vibrations, the acceleration magnitude applied using a shaker was 1 m/s2 at the harvester’s resonance. For random vibrations, a power spectral density (PSD) of 0.1 (m/s2)2/Hz and a frequency range of 10–100 Hz were set. The WSN operated successfully using only energy generated by the harvester and the transmitted waveforms matched the waveforms measured by a high-precision acceleration pick-up. Here, we report the WSN design methodology and the detailed charging characteristics of the energy storage capacitor.","PeriodicalId":89272,"journal":{"name":"Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics","volume":"2 1","pages":"124830R - 124830R-8"},"PeriodicalIF":0.0,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84582082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Self-healable, high-permittivity elastomers for dielectric elastomer actuators 介电弹性体致动器用自愈高介电常数弹性体

Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics Pub Date : 2023-04-28 DOI: 10.1117/12.2658385

Johannes von Szczepanski, Patrick M. Danner, D. Opris

{"title":"Self-healable, high-permittivity elastomers for dielectric elastomer actuators","authors":"Johannes von Szczepanski, Patrick M. Danner, D. Opris","doi":"10.1117/12.2658385","DOIUrl":"https://doi.org/10.1117/12.2658385","url":null,"abstract":"Polar group-modified polysiloxanes obtained by anionic ring-opening polymerization possess high dielectric permittivity and are of great interest for application in dielectric elastomer actuators (DEAs). A self-healing elastomer can be obtained by in situ polymerization and cross-linking using a cyclic siloxane monomer with polar side groups and a cross-linker consisting of multiple connected siloxane rings. In previous works, a non-polar cross-linker has been used, which requires the addition of a solvent for compatibilization with the polar monomer. In polymerization reactions of siloxanes, the addition of solvent leads to a more pronounced formation of cyclic by-products. These cycles impair the mechanical properties of the elastomer and cannot be removed after the reaction, as the material is already cross-linked. Therefore, in this work, we use a polar cross-linker that can be mixed with the polar monomer without adding solvent. Nitrile groups have been studied extensively for increasing the permittivity of the polysiloxane backbone. For a functionalization of 100%, a dielectric permittivity of ~18 was reached. In most cases, the nitrile group was attached to the siloxane backbone in the form of cyanopropyl groups. Still, the influence of the alkyl spacer on the material's dielectric and mechanical properties has not been studied. In this work, we synthesize cyanoalkyl-functional cyclic siloxanes with different lengths of the alkyl spacer and polymerize them solvent-free to high-permittivity polysiloxanes.","PeriodicalId":89272,"journal":{"name":"Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics","volume":"1 1","pages":"124820E - 124820E-8"},"PeriodicalIF":0.0,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76920263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

High-performance dielectric elastomer unimorph bending actuators without pre-stretch 无预拉伸的高性能介电弹性体匀晶弯曲致动器

Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics Pub Date : 2023-04-28 DOI: 10.1117/12.2658231

J. Ehrlich, Peter Löschke, H. Böse

{"title":"High-performance dielectric elastomer unimorph bending actuators without pre-stretch","authors":"J. Ehrlich, Peter Löschke, H. Böse","doi":"10.1117/12.2658231","DOIUrl":"https://doi.org/10.1117/12.2658231","url":null,"abstract":"Dielectric elastomer (DE) single films for bending actuators are normally used with pre-stretch to increase the performance of the actuation. However, pre-stretch requires a high effort in the production of the actuators. In this work, a simple DE bending actuator in a unimorph configuration with high actuation performance is presented. For the manufacturing of the actuator, a silicone film is coated with conductive carbon nanoparticles in a silicone matrix as electrodes on both sides and laminated with a non-stretchable, but highly bendable and light weight polymer film, which acts as a strain limiting layer. Stiffening bars on the strain limiting layer impede an uncontrolled actuator deformation. The bending angle and the displacement of the actuator tip were measured at variable field strength up to 80 kV/mm. In a single DE layer configuration with an electrode area of 50 mm x 30 mm, a bending angle of 15° and a tip displacement of 7 mm were reached. A mathematical model for the bending actuator was applied to compare experimental and theoretical results and to optimize the relevant parameters. By using thermoplastic polyurethane (TPU) as an alternative elastomer material, a bending angle of 40° and a tip displacement of 18 mm could be achieved with the same actuator dimensions and optimized parameters. The simple unimorph bending actuators are promising tools for sensitive grippers on soft robots.","PeriodicalId":89272,"journal":{"name":"Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics","volume":"252 1","pages":"124820W - 124820W-7"},"PeriodicalIF":0.0,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79424063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Silk-printed retroreflective markers for infrastructure-maintenance vehicles in curved tunnels 用于弯曲隧道中基础设施维修车辆的丝印反光标记

Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics Pub Date : 2023-04-28 DOI: 10.1117/12.2656420

Yushan Ke, Yushi Moko, Yuka Hiruma, T. Hayakawa, Elgueta Scarlet, Masatoshi Ishikawa

引用次数: 0

Multilayering VHB films for dielectric elastomer generators with improved lifetime 提高电介质弹性体发电机使用寿命的多层VHB薄膜

Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics Pub Date : 2023-04-28 DOI: 10.1117/12.2657758

Ziqing Han, Yuxuan Guo, Zihang Peng, Roshan Plamthottam, Connor Awe, Alex Rider, R. Kornbluh, R. Pelrine, Q. Pei

{"title":"Multilayering VHB films for dielectric elastomer generators with improved lifetime","authors":"Ziqing Han, Yuxuan Guo, Zihang Peng, Roshan Plamthottam, Connor Awe, Alex Rider, R. Kornbluh, R. Pelrine, Q. Pei","doi":"10.1117/12.2657758","DOIUrl":"https://doi.org/10.1117/12.2657758","url":null,"abstract":"Dielectric elastomer generators (DEGs) can convert mechanical energy into electricity based on variable capacitance. DEGs can potentially harvest energy from renewable energy source such as wind and ocean waves due to their light weight, low cost, and high energy density. To scale up the energy output, multiple single-layer generator units are stacked to form a multilayer DEG. The fabrication of DEGs with reliable multilayer structure having high deformability and long-term stability remains a critical challenge. We report a scalable multilayering technique to produce robust DEG stacks with circular diaphragm configuration. A 4-layer stacked VHB films showed a threefold voltage gain during constant charge operation and an estimated energy density of 100 J/kg. Furthermore, by introducing a dielectric elastomer binder between the VHB films, we demonstrate strong interlayer adhesion in the stacked DEGs, enabling long-term operation stability. As a result, a 4-layer circular diaphragm DEG survived more than 100,000 cycles of mechanical deformation between 0 and 100% area strain. Carbon nanotube (CNT) coating was used as the compliant electrode. Its resistance remains almost constant after 4000 cycles of conditioning.","PeriodicalId":89272,"journal":{"name":"Smart structures and materials. Nondestructive evaluation for health monitoring and diagnostics","volume":"31 1","pages":"124820R - 124820R-11"},"PeriodicalIF":0.0,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81653211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0