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AbstractGraphene is highly regarded as a promising material for various engineering purposes due to its remarkable physical characteristics. However, existing higher-order shear deformation theories may struggle to accurately capture the interlaminar mechanical response of functionally graded graphene nanoplatelets (FG-GNP) reinforced composite beams subjected to thermal loads. This arises from the pronounced discrepancies in material properties and thermal expansion coefficients among the various layers, making the interlaminar mechanical behavior of composite structures exceedingly complex under thermal loading. As a result, a meticulous analysis of interlaminar stresses becomes necessary for the structural assessment of GNP-reinforced composite beams under temperature variations. To overcome this limitation, we propose an advanced model incorporating transverse normal thermal deformation, tailored specifically for FG-GNP reinforced composite beams subjected to thermal loads. The developed model primarily boasts two advantages. Firstly, although transverse normal deformation is introduced into the displacement field, no additional displacement variables are increased, thereby maintaining model simplicity and efficiency. Secondly, the model achieves a high-precision interlaminar shear stress field taking into account the interlaminar continuity conditions and temperature effects. Furthermore, the elimination of second-order derivatives of in-plane displacement parameters from the transverse shear stress components leads to a simplification in the finite element implementation. Based on the proposed model, a simple three-node beam element is constructed. The 3D elasticity solutions and the results from alternative modeling frameworks are used to assess the performance of the developed model. Additionally, a comprehensive investigation is conducted to explore the effects of various parameters on the deformations and stresses of GNP-reinforced composite beams. [ABSTRACT FROM AUTHOR]

Owing to the excellent conductivity and physical properties, graphene can significantly enhance the piezoelectric and mechanical characteristics of the piezoelectric matrix. This article studies the actuation behavior of laminated composite beams integrated with a graphene-reinforced composite piezoelectric (GRCP) actuator. Structural deformations are achieved by interlaminar stresses at interfaces between the piezoelectric actuators and the composite beams. Interlaminar stresses cannot be neglected for the structural analysis of composite beams with a GRCP actuator. Composite beams actuated by GRCP actuators exhibit more complex interlaminar mechanical behavior than traditional composite beams. Existing higher-order shear deformation theories may lose the capability for the actuation behavior of composite beams with GRCP actuators subjected to electromechanical loadings. Thereby, an advanced theory is to be proposed for the actuation performance of GRCP actuators acting on composite beams. Differing from earlier higher-order theories, the proposed theory includes an electromechanical interlaminar shear stress field that can accurately describe the distributions of interlaminar shear stresses without any additional postprocessing procedures. Additionally, a three-node beam element is constructed in terms of the proposed theory. The three-dimensional elasticity solutions, two-dimensional finite element solutions, and the results calculated by the other theories are employed to evaluate the proposed beam theory. Numerical results show that the proposed electromechanical coupling beam model can produce promising results. Additionally, the impacts of significant parameters on the actuation performance of laminated beams with a GRCP actuator are thoroughly investigated. [ABSTRACT FROM AUTHOR]

Graphene is considered as an ideal candidate for composite materials owing to the outstanding physical characteristics. However, existing higher-order shear deformation theories in the literature may meet severe challenges for the accurate prediction of natural frequencies of graphene-reinforced sandwich plates with piezoelectric macro fiber composite (MFC) face sheets. If transverse shear deformations cannot be described accurately, the dynamic behaviors of piezoelectric sandwich plates with graphene reinforcements will be significantly impacted by the large differences of material properties at interfaces of adjacent layers and electro-mechanical coupling characteristic. Thereby, a novel electro-mechanical coupling theory is to be proposed for the free vibration of graphene-reinforced sandwich plates with MFC face sheets. Based on the Reissner mixed variational theorem (RMVT), the precision of the interlaminar shear stresses including the electro-mechanical coupling effect can be improved. The modified interlaminar shear stress field is absorbed in the strain energy, which can enhance the accuracy of the free vibration response of piezoelectric sandwich plates. Additionally, the second-order derivatives of in-plane displacements have been eliminated from the interlaminar shear stress components, which can substantially simplify the finite element implementation. Thus, a simple C0-type finite element formulation is developed for the free vibration of piezoelectric sandwich plates with graphene reinforcements. The 3D elasticity solutions and the results obtained from other theories are used to evaluate the performance of the proposed theory. In comparison with the existing higher-order theories, the proposed theory can produce more accurate results. In addition, a comprehensive parametric study is conducted to explore the impacts of significant parameters on the free vibration behaviors of piezoelectric graphene-reinforced sandwich plates. [ABSTRACT FROM AUTHOR]

Graphene is a highly conductive and exceptional material that has shown potential for significantly improving the piezoelectric and mechanical properties of piezoelectric matrix. This paper examines the stability of composite plates surface bonded with graphene‐reinforced composite piezoelectric (GRCP) actuators. However, the significant differences in material characteristics at the interfaces will pose some challenges in analyzing the buckling behavior of piezoelectric composite plates by means of existing higher‐order shear deformation theories. To address this issue, a refined plate theory is developed for the buckling analysis of piezoelectric composite plates. The developed theory includes a new interlaminar shear stress field that precisely describes the distribution of interlaminar shear stresses, which differs from earlier higher‐order theories. It should be emphasized that the finite element formulation can be simplified by removing the second‐order derivatives of in‐plane displacement parameters from interlaminar shear stresses. In terms of the developed theory, a four‐node C0 quadrilateral plate element is introduced to examine the buckling behavior of piezoelectric composite plates. Furthermore, the modified interlaminar shear stress field is absorbed into the strain energy, significantly improving the ability to predict the critical loads of composite plates with GRCP actuators. The refined plate model is evaluated through the utilization of three‐dimensional (3D) elasticity solutions and results obtained from other associated theories. Numerical results demonstrate that the refined plate model is capable of producing favorable results, and a comprehensive examination is conducted to analyze the effects of significant parameters on the buckling behaviors of piezoelectric composite plates. This study sets a solid foundation for future research and development on the application of graphene‐reinforced composite piezoelectric actuators in composite structures. Highlights: Buckling analysis of composite plates with GRCP actuators is conducted.A refined plate theory with modified interlaminar shear stresses is developed.The ability to predict critical loads can be significantly improved.The finite element formulation can be simplified based on the proposed model.Comprehensive parametric studies on buckling behavior are caried out. [ABSTRACT FROM AUTHOR]

Concrete crack detection is essential for infrastructure safety, and its detection efficiency and accuracy are the key issues. An improved YOLOV5 and three measurement algorithms are proposed in this paper, where the original prediction heads are replaced by Transformer Heads (TH) to expose the prediction potential with one self-attention model. Experiments show that the improved YOLOV5 effectively enhances the detection and classification of concrete cracks, and the Mean Average Precision (MAP) value of all classes increases to 99.5%. The first method is more accurate for small cracks, whilst the average width obtained based on the axial traverse correction method is more exact for large cracks. The crack width obtained from the concrete picture sample is the same as that obtained from the manual detection, with a deviation rate of 0–5.5%. This research demonstrates the recognition and classification of concrete cracks by integrating deep learning and machine vision with high precision and high efficiency. It is helpful for the real-time measurement and analysis of concrete cracks with potential safety hazards in bridges, high-rise buildings, etc. [ABSTRACT FROM AUTHOR]

Remotely operated vehicles (ROVs) and unmanned aerial vehicles (UAVs) provide a solution for dam and bridges structural health information acquisition, but problems like effective damage-related information extraction also occur. Vision-based crack detection methods can replace traditional manual inspection and achieve fast and accurate crack detection. This paper thereby proposes a lightweight, real-time, pixel-level crack detection method based on an improved instance segmentation model. A lightweight backbone and a novel efficient prototype mask branch are proposed to decrease the complexity of the model and maintain the accuracy of the model. The proposed method attains an accuracy of 0.945 at 129 frames per second (FPS). Moreover, our model has smaller volume, lower computational requirements and is suitable for low-performance devices. [ABSTRACT FROM AUTHOR]

Nowadays, graphene is considered as one of the most ideal reinforcements for composite materials due to the outstanding mechanical properties. From the literature survey, it is found that the researches on interlaminar stress analysis of functionally graded graphene reinforced composite (FG-GRC) laminated structures are scarce in literature. If transverse shear deformations are unable to be described accurately, the reasonable design of FG-GRC laminated structures will meet severe challenges due to the differentiation of material properties at the adjacent layers. Thereby, such issue is less studied by using the efficient models, so an advanced mixed-form plate theory is to be proposed for transverse shear stress analysis of FG-GRC laminated plates. The proposed theory can meet beforehand compatible conditions of transverse shear stresses at the interfaces of adjacent laminates and only contains seven independent displacement variables. By applying the three- dimensional (3D) equilibrium equations and the Reissner mixed variational theorem (RMVT), the accurate transverse shear stresses are obtained. The 3D elasticity solutions and the results computed by using the chosen models are selected to appraise the capability of the proposed model. Numerical results show that the proposed plate model can yield accurately transverse shear stresses without any post-processing procedure. In addition, the effects of graphene volume fraction, graphene distribution pattern, lamination sequence, span-to-thickness ratio and aspect ratio on the displacements and stresses of the FG-GRC laminated plates are thoroughly investigated. [ABSTRACT FROM AUTHOR]

In this article, an accurate mixed zigzag theory (HZZTM) is proposed for free vibration analysis of laminated composite and sandwich plates. In-plane displacements in the proposed zigzag theory nonlinearly distribute through the thickness and exhibit an abrupt discontinuity of slope at interfaces, which coincide with three-dimensional analysis. In order to obtain the accurate transverse shear stresses, a preprocessing approach based on the three-dimensional (3D) equilibrium equations and the Reissner mixed variational theorem (RMVT) is used. It is significant that the second-order derivatives of in-plane displacement variables have been removed from the transverse shear stress fields, such that the finite element implementation is greatly simplified. Thus, based on the proposed zigzag model, a computationally efficient C0-type three-node triangular plate element with linear interpolation function is proposed for free vibration analysis of thick laminated composite and sandwich plates. Moreover, the accurate transverse shear stresses are introduced in the dynamic equilibrium equation by employing the Hamilton's principle, which can actively improve the accuracy of natural frequencies of the laminated composite plates with different thickness and material properties at each ply. Performance of the proposed model is assessed by comparing with several benchmark solutions. Agreement between the present results and the reference solutions is very good, and the proposed model only includes the seven displacement variables which can demonstrate the accuracy and effectiveness of the proposed model. [ABSTRACT FROM AUTHOR]

An accurate and computationally attractive global-local higher-order theory (GLHT) is developed for the linearly elastic analysis of cross-ply multilayered composite plates. The theory is derived using the kinematic assumptions of GLHT in conjunction with the Reissner mixed variational principle. For a low-order linear element, it is difficult to accurately compute the transverse shear stresses even applying the three-dimensional equilibrium equation post-processing technique. The reason for this difficulty is that the higher-order derivatives of displacement variables are included in the transverse shear stress fields after using the post-processing technique. Thus, by employing the Reissner mixed variational principle, the higher-order derivatives of displacement variables have been removed from the transverse shear stress components before the finite element procedure is implemented. Based on the mixed GLHT, a computationally efficient C0-type three-node triangular plate element with linear interpolation function is proposed for the analysis of multilayered composite plates. The advantage of the present formulation is that no post-processing approach is needed to calculate the transverse shear stresses while maintaining the computational accuracy of a linear plate element. Performance of the proposed element is assessed by comparing with several benchmark solutions. Numerical results show that the present elements can robustly and accurately predict the displacements and stresses of multilayered composite plates. [ABSTRACT FROM AUTHOR]

Person-centered primary care measures (PCPCM) facilitate high-quality and culturally appropriate primary care. Access to PCPCM remains unequal between rural and urban areas, and the available evidence on rural PCPCM is still lacking. A cross-sectional survey was conducted with stratified sampling by regions, and four districts (Xicheng, Fengtai, Huairou, and Daxing) in Beijing were selected to test the performance of PCPCM in both urban and rural areas. Descriptive statistical methods were used to compare the urban-rural differences in the demographic characteristics of PCPCM. Correlation and regression analyses were performed to determine the associations between PCPCM in demographics and utilization of primary care. The PCPCM showed good reliability and validity in both urban and rural areas (P < .001), slightly lower in rural areas, but scores of rural PCPCM (R-PCPCM) in all items were lower than urban PCPCM (U-PCPCM). Patients in either the preferred urban or rural health centers all showed the highest PCPCM scores, with U-PCPCM= 3.31 for CHCs and R-PCPCM= 3.10 for RHCs, respectively. Patients in urban areas were more likely to receive higher-quality primary care than in rural areas (P < .001). Patients who preferred hospitals (β = 2.61, P < .001) or CHCs (β = 0.71, P = .003) as providers was a significant positive predictor of U-PCPCM but it was the preference for hospitals (β = 2.95, P < .001) for R-PCPCM. Urban-rural differences existed in the performance of PCPCM, with rural areas typically more difficult to access better PCPCM. To promote health equity in rural areas, healthcare providers should strive to minimize urban-rural differences in the quality and utilization of primary care services as much as feasible., (© The Author(s) 2024. Published by Oxford University Press on behalf of International Society for Quality in Health Care. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site–for further information please contact journals.permissions@oup.com.)

Objective: To explore the influence of three central venous catheter biomedical materials (polyurethane, silicone, and polyvinyl chloride) on the proliferation, apoptosis, and cell cycle of Xuanwei Lung Cancer-05 (XWLC-05) cells so as to provide the basis for clinical choice of central venous catheter., Methods: XWLC-05 cells were cultured and subcultured, and the cells at passage 3 were cultured with polyurethane, silicone, and polyvinyl chloride (1.0 cm x 1.0 cm in size), and only cells served as a control. At 24, 48, and 72 hours after cultured, MTT assay was used to detect the cellular proliferation and flow cytometry to detect the cell cycle and apoptosis. At 72 hours after cultured, inverted microscope was used to observe the cell growth., Results: Inverted microscope showed the cells grew well in control group, polyurethane group, and silicone group. In polyvinyl chloride group, the cells decreased, necrosed, and dissolved; residual adherent cells had morphologic deformity and decreased transmittance. At 24 and 48 hours, no significant difference in proliferation, apoptosis, and cell cycle was found among 4 groups (P > 0.05). At 72 hours, the proliferations of XWLC-05 cells in three material groups were significantly inhibited when compared with control group (P < 0.05), and the cells in polyvinyl chloride group had more significant proliferation inhibition than polyurethane group and silicone group (P < 0.05), but there was no signifcant difference in proliferation inhibition between polyurethane group and silicone group (P > 0.05). Compared with the control group, three material groups had significant impact on the rate of apoptosis and cell cycle: polyvinyl chloride group was the most remarkable, followed by silicone group, polyurethane group was minimum (P < 0.05)., Conclusion: Polyvinyl chloride can significantly impact the proliferation, apoptosis, and cell cycle of XWLC-05 cells; polyurethane has better biocompatibility than polyvinyl chloride and silicone.

Background: The interaction of cell and medical biomaterial is one of the significant factors to affect clinical application of medical biomaterial. This research is to investigate three of suture lines how to affect the proliferation and cell cycle of Lung Adenocarcinoma cell A549., Methods: Three of suture lines are respectively cultivated with Lung Adenocarcinoma cell A549, after of 72 hours, to detect absorptance of each groups by MTT method in order to reflect the proliferation of Lung Adenocarcinoma cell A549 and to detect percentage of G1 period cell and S period cell of each of groups by flow cytometry., Results: Different of suture lines have effect differently on the proliferation and cell cycle of Lung Adenocarcinoma cell A549 (P<0.05). The effect of absorbent suture line on the proliferation and cell cycle of Lung Adenocarcinoma cell A549 is strong, the effect of chorda serica chirurgicalis is medium, the effect of slide wire is poor. Different length of each suture line have effect differently on the proliferation and cell cycle of Lung Adenocarcinoma cell A549 (P<0.05)., Conclusions: Three of suture line materials have different effect on the proliferation and cell cycle of Lung Adenocarcinoma cell A549, to reflect dose-effect relation.