Regarding the problem of automatic detection in art teaching classroom behavior, the research combines the YOLOv5 algorithm in the deep learning algorithm and adds a two-way feature information ...pyramid function with weighting capability to the neck part of the algorithm to achieve performance-based algorithm improvement. This research prunes and optimizes the model for the campus technology implementation problem to improve the robustness and ease of implementation of the model. The model is designed in line with the model of the art teaching classroom behavior training set, and the applied experimental method is adopted for analysis. The results show that the average accuracy of all classes of state classification is 0.973 level after model improvement, the average accuracy of all classes of state classification is 0.970 level after model pruning, and the realizability of the model is significantly enhanced while the performance and efficiency are improved. Therefore, the research-designed classroom behavior detection and analysis model for art teaching can effectively detect the types of classroom behaviors of students in the process of art teaching with excellent performance, providing an effective way to ensure the quality of student learning in classroom teaching.
This paper presents an extensive laboratory investigation of the non-linear rheological mechanical characteristics of hard rock under cyclic incremental loading and unloading. A data processing ...algorithm is proposed to analyze the experimental data, determine the instantaneous elastic and plastic strain components, visco-elastic and visco-plastic strain components from the total strain, and separate the visco-elastic and visco-plastic strain curves from the total creep strain curves. The elasto-viscoplastic rheological behavior of iherzolite specimens at various confining pressures is thoroughly studied using the obtained experimental data. Based on the data, a non-linear elasto-viscoplastic rheological model containing various deformation components is proposed, by connecting a Hooke body, a parallel combination of Hooke and plastic slide bodies, a Kelvin body, and a generalized Bingham body.
The proportion of instantaneous plastic strain component in the total instantaneous strain has increasing tendency with higher deviatoric stress on a whole. The instantaneous elastic modulus of specimen tends to increase with higher deviatoric stress and confining pressure, the instantaneous plastic modulus of specimen is decreased with higher deviatoric stress at confining pressures of 3 and 6MPa on the whole, however, has no evident relationship with deviatoric stress, when confining pressure is increased to 9 and 16MPa. The proportion of the visco-plastic strain component in the creep strain is increased with higher deviatoric stress. The steady-state creep strain rate versus deviatoric stress relationship can be well described with an exponential expression. The elasto-viscoplastic characteristics of radial creep is similar to that of axial creep, but radial creep strain is only 25–30% of axial creep strain, steady-state creep rate in radial direction is about 35% of that in axial direction.
•A data processing algorithm was proposed to analyze the experimental data under cyclic incremental loading and unloading to determine elasto-viscoplastic strain components, and separate the visco-elastic and visco-plastic strain curves from the total creep strain curves.•The proportion of the visco-plastic strain component in the creep strain is increased with higher deviatoric stress. The steady-state creep strain rate versus deviatoric stress relationship can be well described with an exponential expression.•A nonlinear EVPR model containing various deformation components is proposed, which can describe the loading and unloading creep behavior well and give a precise description of the full stages of creep, especially the tertiary creep stage.
The transport sector is recognized as one of the largest carbon emitters. To achieve China’s carbon peak commitment in the Paris Agreement on schedule, it is indispensable to explore the peak carbon ...emissions and mitigation strategies in the transport sector. Many researches in the past have contextualized in China’s total emissions peak, while the study about forecasting China’s transport CO
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emissions peak seldom appeared, especially the application of intelligent prediction model. To further investigate the determinants and forecast the peak of transport CO
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emissions in China accurately, a novel bio-inspired prediction model is proposed in this paper, namely, the extreme learning machine (ELM) optimized by manta rays foraging optimization (MRFO), hereafter referred as MRFO-ELM. Adhering to this hybrid model, the mean impact value (MIV) method is then employed to evaluate and differentiate the importance of thirteen influencing factors. Additionally, three scenarios are set to conduct prediction of China’s transport CO
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emissions. The empirical results indicate that the proposed MRFO-ELM has excellent performance in terms of the optimization searching velocity and prediction accuracy. Simultaneously the level of vehicle electrification is verified to be one of the emerging major factors affecting China’s transport CO
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emissions. The transport CO
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emissions in China would peak in 2039 under the baseline model scenario, while the plateau would occur in 2035 or 2043 under sustainable development mode and high growth mode, respectively. The peak years imply much pressure on China’s transport carbon emissions abatement currently, whereas active policy adjustments can effectively urge the earlier occurrence of the emission peak. These new findings suggest that it is essential for China to improve the energy mix and encourage the electric energy replacement in line with urbanization pace, so as to achieve CO
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emissions mitigation in the transport industry.
The prevalence of inflammatory bowel disease (IBD), which includes ulcerative colitis (UC) and Crohn’s disease (CD), increases gradually worldwide in the past decades. IBD is generally associated ...with the change of the immune system and gut microbiota, and the conventional treatments usually result in some side effects. Bifidobacterium longum, as colonizing bacteria in the intestine, has been demonstrated to be capable of relieving colitis in mice and can be employed as an alternative or auxiliary way for treating IBD. Here, the mechanisms of the Bifidobacterium longum in the treatment of IBD were summarized based on previous cell and animal studies and clinical trials testing bacterial therapies. This review will be served as a basis for future research on IBD treatment.
Associations between anxiety, depression and adolescent Internet addiction have been well documented in the literature; however, few published studies have examined these relationships considering ...the developmental trajectory courses of adolescent Internet addiction as well as the individual differences over time. Using a sample of 1545 Chinese adolescents and 3 waves of data over six months, we examined the longitudinal associations between anxiety and depression and Internet addiction, considering sex and obesity. We used latent growth curve modeling (LGCM) to examine the overall conditions of Internet addiction, and latent class growth modeling (LCGM) to determine adolescent developmental membership for Internet addiction. Both unconditional and conditional models were performed. Anxiety and depression were analyzed as time-varying variables, and sex and obesity as time-invariants in our conditional models. Overall, there was a linear decline in adolescent Internet addiction over the six months. Anxiety and depression positively predicted adolescent Internet addiction. Two developmental trajectory patterns for Internet addiction were determined (i.e., low/declining, high/declining). Anxiety was associated with adolescent Internet addiction for both groups of adolescents, but depression was associated with Internet addiction only for adolescents who followed a low/declining course of Internet addiction. Boys reported a higher mean score of Internet addiction at the initial status than girls, and boys also had a faster, declining rate of change over the six months than girls. Obesity was not a predictor of Internet addiction. The results spoke to the importance of considering mental health problems and sex in any intervention efforts to reduce adolescent Internet addiction. Limitations of the study were discussed.
•Anxiety and depression positively are associated with Internet addiction over time.•Adolescents follow different developmental courses of Internet addiction.•Sex is a key variable in understanding Internet addiction.•Obesity is not related to Internet addiction over time.
Transient pulse tests were performed on single rock fractures at different confining pressures. A new data analysis method based on polynomial fitting was introduced to investigate the relationship ...between flow velocity and hydraulic gradient. 3D laser scanning was used to quantify the morphological changes of the fracture surface after the transient pulse test or under the hydro-mechanical coupling effect. The results show that the flow velocity versus hydraulic gradient data gradient shows a nonlinear relationship at very low hydraulic, possibly due to strong solid-water interaction, but becomes approximately linear after the hydraulic gradient is high enough. The permeability of a single fracture is sensitive to the confining pressure. As the confining pressure increases, the permeability first remarkably decreases when the confining pressure is lower than a certain value and then decreases at a much lower speed when the confining pressure is higher than that value. Both mechanical and hydraulic apertures decrease at a decreasing rate with the increase in confining pressure. The effect of fracture roughness on the permeability is related to the magnitude of the confining pressure. Rougher fractures have lower permeability at low confining pressures; but the opposite can be true when the confining pressure is high enough. Roughness is no longer critical to permeability when the confining pressure is over a certain value.
•A new method based on polynomial fitting is introduced to analyze the pulse decay data.•The permeability first remarkably decreases with higher confining pressure and then at a much slower speed.•The effect of fracture roughness on the permeability is related to the confining pressure.•The hydro-mechanical coupling reduces the roughness of rock fractures.
This paper investigates the cracking and stress–strain behavior, especially the local strain concentration near the flaw tips, of rock-like material containing two flaws. A series of uniaxial ...compression tests were carried out on rock-like specimens containing two flaws, with strain gauges mounted near the flaw tips to measure the local strain concentration under the uniaxial compressive loading. Four different types of cracks (wing cracks, anti-wing cracks, coplanar shear cracks and oblique shear cracks) and seven patterns of crack coalescences (T1 and T2; S1 and S2; and TS1, TS2 and TS3) are observed in the experiments. The type of crack coalescence is related to the geometry of the flaws. In general, the crack coalescence varies from the S-mode to the TS-mode and then to the T-mode with the increase of the rock bridge ligament angle. The stress–strain curves of the specimens containing two flaws are closely related to the crack development and coalescence process. The strain measurements indicate that the local tensile strain concentration below or above the pre-existing flaw tip causes wing or anti-wing cracks, while the local compressive strain concentration near the flaw tip is related to the shear crack. The measured local tensile strain shows a jump at the initiation of wing- and anti-wing cracks, reflecting the instant opening of the wing- and anti-wing crack propagating through the strain gauge. During the propagation of wing- and anti-wing cracks, the measured local tensile strain gradually increases with few jumps, implying that the opening deformation of wing- and anti-wing cracks occurs in a stable manner. The shear cracks initiate followed by a large and abrupt compressive strain jump and then quickly propagate in an unstable manner resulting in the failure of specimens.
This study aims to map the intellectual structure of social media research in China from 2006 to 2013. Bibliometric and co-word analysis were employed to reveal the characteristics and status on ...social media research in China. Data was collected from China Academic Journals Full-text Database during the period of 2006–2013. In bibliometric analysis, descriptors of years, themes, subjects, institutions and authors were applied to obtain the research characteristics of social media. In co-word analysis, hierarchical cluster analysis, strategic diagram and social network analysis were adopted. Main results show that, a total of 3178 CSSCI papers on social media have risen yearly and exponentially. The most and distinctive themes were microblog, blog, virtual community and social networking site. The most common subject was News and media, followed by Library, information and digital library, Computer software and application. Wuhan University, Renmin University of China and Nanjing University ranked the top three on the most publications. And the distribution of number of authors with different publications obeys power-law distribution. Moreover, the number of keyword frequency obeys power-law distribution. The core keywords include social media, traditional media, Internet, dissemination and user. There are ten research directions on social media in China, some of which are highly correlated. Generally, the relatively dispersive distribution of research topics suggests the imbalanced development on social media research in China. Some hot topics are well-developed and tend to be mature, a few topics have a great potential for further development, and many other topics are marginal and immature.
Ship fire is one of the greatest dangers to ship navigation safety. Nevertheless, typical detection methods have limited detection effectiveness and accuracy due to distance restrictions and ship ...motion. Although the issue can be addressed by image recognition algorithms based on deep learning, the computational complexity and efficiency for ship detection are tough. This paper proposes a lightweight target identification technique based on the modified YOLOv4-tiny algorithm for the precise and efficient detection of ship fires, taking into account the distinctive characteristics of ship fires and the marine environment. Initially, a multi-scale detection technique is applied to broaden the detection range and integrate deep semantic information, thereby enhancing the feature information of small targets and obscured objects and improving the detection precision. Then, the proposed algorithm employs the SE attention mechanism for inter-channel feature fusion to improve the capability of feature extraction and the precision of ship fire detection. Last but not least, picture transformation and migration learning are added to the small ship fire dataset to accelerate the convergence pace, improve the convergence effect, and reduce dataset dependence. The simulation experiments reveal that the proposed I-YOLOv4-tiny + SE model outperforms the benchmark algorithm in terms of ship fire detection accuracy and detection efficiency and that it satisfies the real-time ship fire warning criteria in demanding maritime environments.
Implementation of hybrid energy system (HES) is generally considered as a promising way to satisfy the electrification requirements for remote areas. In the present study, a novel decision making ...methodology is proposed to identify the best compromise configuration of HES from a set of feasible combinations obtained from HOMER. For this purpose, a multi-objective function, which comprises four crucial and representative indices, is formulated by applying the weighted sum method. The entropy weight method is employed as a quantitative methodology for weighting factors calculation to enhance the objectivity of decision-making. Moreover, the optimal design of a stand-alone PV/wind/battery/diesel HES in Yongxing Island, China, is conducted as a case study to validate the effectiveness of the proposed method. Both the simulation and optimization results indicate that, the optimization method is able to identify the best trade-off configuration among system reliability, economy, practicability and environmental sustainability. Several useful conclusions are given by analyzing the operation of the best configuration.
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