Composites Science and Technology最新文献

Sequential multiscale simulation of heat transfer and experimental verification of porous phenolic resin composites under Knudsen effect

IF 8.3 1区材料科学

Composites Science and Technology Pub Date : 2024-12-02 DOI: 10.1016/j.compscitech.2024.110990

Bo Li , Kuibao Zhang , Jun Jiang , Youan Shi , Zhonghao Ming , Tingze Chen

{"title":"Sequential multiscale simulation of heat transfer and experimental verification of porous phenolic resin composites under Knudsen effect","authors":"Bo Li , Kuibao Zhang , Jun Jiang , Youan Shi , Zhonghao Ming , Tingze Chen","doi":"10.1016/j.compscitech.2024.110990","DOIUrl":"10.1016/j.compscitech.2024.110990","url":null,"abstract":"<div><div>The randomness and multi-level structures inherent to porous composites with open-pore make it difficult to establish equivalent geometric models at different scales for multi-scale simulations. This paper presents a combined experimental and simulation approach to the preparation, structural analysis and multiscale simulation of quartz fibre-reinforced phenolic composites. The elementalized open-pore porous models with the Knudsen effect, the random fibre yarn models and the random fibre felt models have been established and assembled into a composite structural model after homogenization. The thermal conductivity parameters of the porous model are calculated and transferred to the fibre yarn and fibre felt models for simulation. Thereafter, the thermal conductivity parameters of the three models are transferred to the composite structure model and simulated to obtain its equivalent thermal conductivity. The experimental and simulation results demonstrate that the introduction of the Knudsen effect can reduce the simulation error of the composite structure model by an order of magnitude. In combination with the random contact characteristics of the yarns, the sequential multiscale finite element heat transfer simulation with an error of 0.5 % can be achieved.</div></div>","PeriodicalId":283,"journal":{"name":"Composites Science and Technology","volume":"260 ","pages":"Article 110990"},"PeriodicalIF":8.3,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Lightweight and mechanically strong MXene-Based microcellular nanocomposite foams for integrated electromagnetic interference shielding and thermal management

IF 8.3 1区材料科学

Composites Science and Technology Pub Date : 2024-11-27 DOI: 10.1016/j.compscitech.2024.110988

Zhonglei Ma , Ruochu Jiang , Yu Zhang , Li Ma , Yang Bai , Kefan Zhang , Xinpei Zuo , Yue Zuo , Haoyu Jing , Jianbin Qin , Guangcheng Zhang

{"title":"Lightweight and mechanically strong MXene-Based microcellular nanocomposite foams for integrated electromagnetic interference shielding and thermal management","authors":"Zhonglei Ma , Ruochu Jiang , Yu Zhang , Li Ma , Yang Bai , Kefan Zhang , Xinpei Zuo , Yue Zuo , Haoyu Jing , Jianbin Qin , Guangcheng Zhang","doi":"10.1016/j.compscitech.2024.110988","DOIUrl":"10.1016/j.compscitech.2024.110988","url":null,"abstract":"<div><div>Lightweight and mechanically strong multifunctional nanocomposites with integrated electromagnetic interference (EMI) shielding and thermal management capacities are urgently required for protection of emerging aerospace, portable smart electronics and telecommunication devices. Herein, the lightweight, mechanically strong and flame-retardant microcellular aramid nanofiber/Ti<sub>3</sub>C<sub>2</sub>T<sub>x</sub> MXene (ANF/Ti<sub>3</sub>C<sub>2</sub>T<sub>x</sub>) nanocomposite foams are developed for integrated EMI shielding and thermal management by the feasible hydrogen bonding assembly, vacuum-assisted filtration and thermal treatment strategy using the solid sacrificial templates. Thanks to the synchronous construction of three-dimensional (3D) continuous conductive networks and microcellular structures, the microcellular nanocomposite foams possess low mass density of 0.29 g/cm<sup>3</sup>, superior EMI shielding effectiveness (EMI SE) of 64.9 dB, and high EMI SE/t of 10970.3 dB cm<sup>2</sup>/g, as well as outstanding mechanical properties with an improved tensile strength of 16.5 MPa and excellent flame retardancy. Moreover, the microcellular nanocomposite foams show excellent thermal management performances with intelligently tailorable Joule heating temperatures at low voltages and significant working reliability. Therefore, the lightweight, mechanically strong and flame-retardant MXene-based microcellular nanocomposite foams are promising for emerging EMI shielding and thermal management applications in aerospace, portable smart electronics and telecommunication devices.</div></div>","PeriodicalId":283,"journal":{"name":"Composites Science and Technology","volume":"260 ","pages":"Article 110988"},"PeriodicalIF":8.3,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142743023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Characterization and modelling of the microstructural and mechanical properties of additively manufactured continuous fiber polymer composites

IF 8.3 1区材料科学

Composites Science and Technology Pub Date : 2024-11-26 DOI: 10.1016/j.compscitech.2024.110986

Pietro Cuccarollo, Alessandro Pontefisso, Paolo Andrea Carraro, Marino Quaresimin

引用次数: 0

Multi-scale numerical calculations for the interphase mechanical properties of carbon fiber reinforced thermoplastic composites

IF 8.3 1区材料科学

Composites Science and Technology Pub Date : 2024-11-26 DOI: 10.1016/j.compscitech.2024.110982

Zheng Li , Bo Wang , Peng Hao , Kaifan Du , Zebei Mao , Tong Li

{"title":"Multi-scale numerical calculations for the interphase mechanical properties of carbon fiber reinforced thermoplastic composites","authors":"Zheng Li , Bo Wang , Peng Hao , Kaifan Du , Zebei Mao , Tong Li","doi":"10.1016/j.compscitech.2024.110982","DOIUrl":"10.1016/j.compscitech.2024.110982","url":null,"abstract":"<div><div>This study employs a multi-scale numerical calculations method based on molecular dynamics and finite element modeling to investigate the stress transfer mechanisms within the interphase of unidirectional (UD) carbon fiber reinforced thermoplastic polymers (CFRTP) composites, based on which exponential decay model (EDM) was developed to predict the interphase strength and modulus. Revealing that the interphase strength and modulus are approximately 0.5–0.7 times that of the fibre/interphase interface or 1.2 to 1.7 times matrix. The EDM was validated using a coupled experimental-representative volume element modeling method. By calibrating the interphase fracture energy, the mechanical properties predicted by the EDM aligned well with the experimental results of UD CFRTP composites. Finally, the damage evolution and failure modes were analyzed, revealing that the transverse failure of UD CFRTP composites is dominated by the interphase, while longitudinal failure is primarily governed by the fibers, consistent with scanning electron microscope observations. This confirms the accuracy of the EDM, and application this method can be used to quickly and accurately assess the strength and modulus of the interphase in CFRTP composites to significantly reduce the numerical analysis time.</div></div>","PeriodicalId":283,"journal":{"name":"Composites Science and Technology","volume":"260 ","pages":"Article 110982"},"PeriodicalIF":8.3,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142757010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Porous conductive composite as piezoresistive sensors for smart safety helmet

IF 8.3 1区材料科学

Composites Science and Technology Pub Date : 2024-11-26 DOI: 10.1016/j.compscitech.2024.110985

Suhyeon Kim , Yeonhee Heo , Hyein Jung , Jeongmin Yoo , Jin-Tae Kim , Yoonseok Park

{"title":"Porous conductive composite as piezoresistive sensors for smart safety helmet","authors":"Suhyeon Kim , Yeonhee Heo , Hyein Jung , Jeongmin Yoo , Jin-Tae Kim , Yoonseok Park","doi":"10.1016/j.compscitech.2024.110985","DOIUrl":"10.1016/j.compscitech.2024.110985","url":null,"abstract":"<div><div>Safety helmets are essential protective gear for workers in hazardous environments, capable of reducing external impact forces by 90 %. Proper wearing of a helmet in any situation is crucial for ensuring maximum protection. In dangerous scenarios, if a helmet is dislodged or misaligned due to an external impact, it makes following impacts difficult to prevent. Quick adjustment to the correct position is essential. In this context, it is important to develop a smart helmet system capable of monitoring the spatial pressure distribution that shows proper usage of helmet at the boundary between the helmet and head. Such a system could further provide guidance to users for proper wearing, enhancing safety in the work environment. This paper introduces the micro-porous elastomeric conductive composite as a soft, ultra-sensitive pressure sensor for low pressure regime (0–200 kPa). The sensor combines with a vibrotactile actuator and microcontroller, creating a haptic interface that responds to changes in pressure. Integrating haptic interfaces into safety helmets, smart helmets yield a system capable of real-time measurement of pressure between the helmets and head and delivers the wearing conditions to users. Detailed research into the materials, mechanical engineering aspects of this device, along with pilot perception tests, establishes the technical foundation and measurement capabilities of the proposed system.</div></div>","PeriodicalId":283,"journal":{"name":"Composites Science and Technology","volume":"260 ","pages":"Article 110985"},"PeriodicalIF":8.3,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142757009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Theory-guided machine learning for thermal modeling of in-situ automated fiber placement of thermoplastic composites

IF 8.3 1区材料科学

Composites Science and Technology Pub Date : 2024-11-23 DOI: 10.1016/j.compscitech.2024.110987

A. Fontes , N. Zobeiry , F. Shadmehri

{"title":"Theory-guided machine learning for thermal modeling of in-situ automated fiber placement of thermoplastic composites","authors":"A. Fontes , N. Zobeiry , F. Shadmehri","doi":"10.1016/j.compscitech.2024.110987","DOIUrl":"10.1016/j.compscitech.2024.110987","url":null,"abstract":"<div><div>In-situ Automated Fiber Placement (AFP) of thermoplastic composites has several advantages over traditional manufacturing techniques, with the main benefit being eliminating secondary thermal processing. Without secondary heat treatment, the in-situ thermal history becomes the critical process parameter that governs bond development, crystallization kinetics, and the development of residual stresses. This work improves the thermal modeling of the in-situ Automated Fiber Placement (AFP) manufacturing process by leveraging Theory-Guided Machine Learning (TGML). A novel theory-guided neural network (TgNN) with theory-based pre-layer transforms models the three-dimensional temperature distribution during in-situ AFP manufacturing. The TgNN is fit on experimentally measured temperatures for various combinations of hot gas torch temperatures and heat source velocities. Feature engineering is implemented by applying theory-based pre-layer transforms to the input features time, the thermocouple coordinates, hot gas torch temperature, and heat source velocity. Compared to a theory-agnostic neural network, the TgNN with theory-based pre-layer transforms has improved predictive ability and requires fewer training data for equivalent performance. The trained model is computationally efficient and can be leveraged for online process control.</div></div>","PeriodicalId":283,"journal":{"name":"Composites Science and Technology","volume":"260 ","pages":"Article 110987"},"PeriodicalIF":8.3,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Enhancement of radar-infrared stealth performance of EPDM-based composites through the asymmetric sandwich structural construction 通过非对称夹层结构提高 EPDM 基复合材料的雷达-红外隐形性能

IF 8.3 1区材料科学

Composites Science and Technology Pub Date : 2024-11-23 DOI: 10.1016/j.compscitech.2024.110981

Zikang Han, Rong Chen, Jiang Li, Shaoyun Guo

{"title":"Enhancement of radar-infrared stealth performance of EPDM-based composites through the asymmetric sandwich structural construction","authors":"Zikang Han, Rong Chen, Jiang Li, Shaoyun Guo","doi":"10.1016/j.compscitech.2024.110981","DOIUrl":"10.1016/j.compscitech.2024.110981","url":null,"abstract":"<div><div>The development of radar-infrared-compatible stealth materials is crucial for the weaponry stealth field. However, reconciling the mechanistic contradiction between radar and infrared stealth remains a challenge. In this study, an asymmetrical sandwich structure composite was developed, with an absorbing layer situated in the middle and low emissivity layers on either side. The structure and properties of the functional layers were optimized: In the absorbing layer, ethylene propylene diene monomer/carbon nanotubes/silica (EPDM/CNTs/SiO<sub>2</sub>) was foamed to enhance its microwave absorption and thermal insulation properties. In the low emissivity layers, the orientation of the flake aluminum powders was adjusted to reduce the infrared emissivity to as low as 0.236 and 0.183 at 3∼5 and 8∼14 μm, respectively. As a result, the composite achieved an effective absorption bandwidth of 7.26 GHz and maintained an equilibrium temperature of 29.4 °C after being placed on a 60 °C hot stage, demonstrating excellent infrared stealth performance. Additionally, the composite has a suitable density (0.77 g/cm<sup>3</sup>) and thickness (3.58 mm). Considering its broad bandwidth, low emissivity, lightness, and softness, the sandwich structure composite is suitable for compatible stealth applications.</div></div>","PeriodicalId":283,"journal":{"name":"Composites Science and Technology","volume":"260 ","pages":"Article 110981"},"PeriodicalIF":8.3,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","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 green mechanical recycling strategy for carbon fiber-reinforced polymer laminates based on the glass transition principle 基于玻璃化转变原理的碳纤维增强聚合物层压板新型绿色机械回收策略

IF 8.3 1区材料科学

Composites Science and Technology Pub Date : 2024-11-22 DOI: 10.1016/j.compscitech.2024.110983

Mingfei Xing , Zhan Li , Wanting Xu , Fayang Guo , Li Zhao , Jiacheng Wang , Ruyue Yin , Yaping Wang

{"title":"A novel green mechanical recycling strategy for carbon fiber-reinforced polymer laminates based on the glass transition principle","authors":"Mingfei Xing , Zhan Li , Wanting Xu , Fayang Guo , Li Zhao , Jiacheng Wang , Ruyue Yin , Yaping Wang","doi":"10.1016/j.compscitech.2024.110983","DOIUrl":"10.1016/j.compscitech.2024.110983","url":null,"abstract":"<div><div>A novel glass transition-assisted mechanical delamination process was developed for the environmentally friendly and high-value recovery of carbon fiber reinforced polymer (CFRP) laminates. When heated to 250–350 °C for 5–15 min in an air atmosphere, the resin matrix quickly transitioned from a rigid glassy state to a flexible rubbery state, making the CFRP laminates soft and bendable. Simultaneously, the shear strength of the resin in the rubbery state decreased significantly to 0.35%–4.58 % of its original value. The softened CFRP laminates could be easily bent by a bending machine. Excessive bending deformation caused the resin between adjacent carbon fiber (CF) sheets to tear and debond, resulting in delamination of the laminates into individual CF sheets. Upon cooling to the glassy state, the shear strength of the resin was restored to 87.59%–98.55 % of its original value. This mild glass transition treatment did not significantly affect the mechanical properties of the CF. The resulting monolayer CF sheets could be easily cut into thin slices or filaments of uniform size and hot-pressed into new CFRP plates. The flexural and tensile strengths of the refabricated CFRP plates were approximately 58.98%–82.71 % and 54.55%–87.79 % of those of the original laminates, respectively.</div></div>","PeriodicalId":283,"journal":{"name":"Composites Science and Technology","volume":"260 ","pages":"Article 110983"},"PeriodicalIF":8.3,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142702822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Millimeter-scale macrocapsules with cold energy storage and temperature indication for vaccine storage 用于疫苗储存的具有冷能储存和温度指示功能的毫米级大胶囊

IF 8.3 1区材料科学

Composites Science and Technology Pub Date : 2024-11-22 DOI: 10.1016/j.compscitech.2024.110975

Zide Wu , Zhicheng Wang , Xinyu Zhai , Shuai Yin , Xiaotian Peng , Haoyu Jiang , Hao Peng

{"title":"Millimeter-scale macrocapsules with cold energy storage and temperature indication for vaccine storage","authors":"Zide Wu , Zhicheng Wang , Xinyu Zhai , Shuai Yin , Xiaotian Peng , Haoyu Jiang , Hao Peng","doi":"10.1016/j.compscitech.2024.110975","DOIUrl":"10.1016/j.compscitech.2024.110975","url":null,"abstract":"<div><div>This study aims to prepare millimeter-scale macrocapsules with cold energy storage and temperature indication suitable for the requirement of vaccine storage (−25 °C ∼ -15 °C). In these macrocapsules, reversible thermochromic microencapsulated phase change materials (TC-MPCMs) are used as dispersions, and flexible calcium alginate is served as the polymer matrix. Macrocapsules exhibit a particle size distribution from 0.5 mm to 3.0 mm, with a melting temperature of −18.4 °C, a melting enthalpy of 86.0 J/g and an encapsulation efficiency of 45.5 %. After melting of the PCMs (Phase change materials), these macrocapsules can undergo a reversible discoloration, with a color difference of 27.54. Additionally, the volatilization of internal PCMs can also trigger the discoloration reaction. After 100 thermal cycles, the latent heat loss of the macrocapsules is less than 5 %, and the calcium alginate shell material delays the thermal decomposition of internal PCMs. Finally, the storage-release cold energy test shows that at 25 °C, the macrocapsules can maintain the ideal temperature range (−25 °C ∼ -15 °C) for 10.34 min. The millimeter-scale macrocapsules successfully address the issues of ultrafine powder contamination, difficulty in reuse and recycling of micron-scale TC-MPCMs, and show excellent potential for vaccine frozen storage.</div></div>","PeriodicalId":283,"journal":{"name":"Composites Science and Technology","volume":"260 ","pages":"Article 110975"},"PeriodicalIF":8.3,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","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 and multi-UV curable materials adaptable photothermal nanoparticles for near-infrared-responsive digital light processing based 4D printing 用于基于近红外响应式数字光处理的 4D 打印的高性能和多紫外固化材料适应性光热纳米粒子

IF 8.3 1区材料科学

Composites Science and Technology Pub Date : 2024-11-22 DOI: 10.1016/j.compscitech.2024.110984

Shiwei Feng, Jingjing Cui, Yunlong Guo, Weizi Gao, Yongding Sun, Chen Liang, Zhe Lu, Biao Zhang

{"title":"High performance and multi-UV curable materials adaptable photothermal nanoparticles for near-infrared-responsive digital light processing based 4D printing","authors":"Shiwei Feng, Jingjing Cui, Yunlong Guo, Weizi Gao, Yongding Sun, Chen Liang, Zhe Lu, Biao Zhang","doi":"10.1016/j.compscitech.2024.110984","DOIUrl":"10.1016/j.compscitech.2024.110984","url":null,"abstract":"<div><div>Integration of functional nanomaterials into 3D printing polymers expands the versatility of 4D printing. However, high performance and multi-UV curable materials adaptable nanoparticles for 4D printing are still urgently needed to avoid printing complications and deformation limitations caused by high filler loadings. Here, high performance oxygen-deficient tungsten oxide nanoparticles (WO<sub>3-x</sub> NPs) are synthesized via a straightforward hydrothermal method, and the resulting nanoparticles (NPs) exhibit excellent photothermal property which can rapidly increase from room temperature to 562.6 °C in less than 2 s via near-infrared (NIR) light irradiation. Moreover, these NPs can also be well dispersed in a wide range of photocurable polymers, such as UV curable hydrogel, shape memory polymer, and dual-curing polymer, forming variety of nanocomposite systems. The formed nanocomposite systems can be manufactured into complex 3D structures via digital light processing based 4D printing. Just trace WO<sub>3-x</sub> NPs in nanocomposite systems (<2 wt‰) can help realize the controllable photothermal properties of the printed structures, which are capable of arbitrary spatial deformation, remote-controlled distortion, and on-demand reinforcement in response to NIR irradiation, presenting a succinct and impactful approach to broadening the application scope of light-controlled DLP-based 4D printing.</div></div>","PeriodicalId":283,"journal":{"name":"Composites Science and Technology","volume":"260 ","pages":"Article 110984"},"PeriodicalIF":8.3,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142702823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0