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In order to solve the challenges brought by multi-source and cross-domain scenarios to online music education, this paper designs an online music education system based on advanced artificial intelligence technology, which can provide personalized learning course resource recommendations for music online learners. The system includes four layers, consisting of user interface layer, application module layer, function module layer and data storage layer. At the application module level, this paper proposes a music recommendation algorithm based on a personalized multimodal network model. The recommendation algorithm performs music information retrieval (MIR) based on the similarity judgment of the contour of music pitch and the overall change, and constructs a multimodal network model based on the user's preference for resources to achieve personalized music recommendation. This paper crawls more than one million music score data from a well-known music platform database in China to establish a dataset to evaluate the performance of this method. The comparison results with three existing works show that the method proposed in this paper has good performance and can provide users with suitable music recommendations. The artificial intelligence technology-driven online music education mechanism proposed in this paper has good prospects. [ABSTRACT FROM AUTHOR]

The low-medium maturity shale oil in China has large resource potential. The occurrence state of such resource is mainly retained hydrocarbon and unconverted organic substance, making the in-situ conversion process a requisite technology. Meanwhile, the naturally fractured shale reservoir has multiple types of pore space, making the hydrothermal coupling process more complex. In this paper, a coupled thermal-reactive compositional flow model and numerical solution method is proposed. Specifically, the apparent permeability of fractured shale oil reservoir is derived based on fractal theory. Besides, the multistage parallel chemical kinetic reactions during in-situ conversion process and evolution of reservoir fluid composition and shale porosity are incorporated. Then the accuracy of the proposed model is tested through numerical cases. Finally, the impact of key operation parameters and fractal parameters on shale oil exploitation is analyzed, such as heating temperature, heating spacing, pore size fractal dimension, fracture length fractal dimension and tortuosity fractal dimension. The proposed model is capable of accurate and efficient prediction of the fractured low-medium maturity shale oil reservoir production. [ABSTRACT FROM AUTHOR]

The purposes of this paper are to analyze the financial management and influencing factors of small and medium-sized enterprises (SMEs) and explore the nonlinear relationship in enterprises' financial market structure. The small and medium-sized enterprises in Eastern and Western China are taken as the research objects. First, the relationships between asset–liability constraints and financial management are discussed, analyzed, and explained. The development of enterprises' financial management under the asset–liability constraints system is emphasized. Second, a self-adaptive nonlinear dynamic system is proposed based on dynamic surface control and the multi-directional and uncertain control of the financial market structure. Finally, a dynamic nonlinear panel estimation model for enterprises is constructed based on the nonlinear system. The simulation and empirical analysis results confirm that the proposed nonlinear system is useful in dynamic, uncertain control problems. The statistical results of the three primary indicators, economic variables, financial indicators, and control variables, reveal the significant regional differences of different financial market structure indicators. Model estimates based on the three key sub-indicators, the leverage ratio, return on assets, and debt interest rate, reveal the differences in financing and leverage ratio of small and medium-sized enterprises located in the eastern and western regions. SMEs in Eastern China are taken as examples; the direct financing rate and insurance proportion are negatively correlated with the leverage ratio and debt interest rate. In contrast, they are positively correlated with asset returns. In conclusion, there are noticeable differences in the financial market structure between different regions. [ABSTRACT FROM AUTHOR]

The aim of this paper is to improve the accurate analysis of the sports training project, research its video data profoundly, and discover deficiencies and summarize experience from the existing videos, thereby promoting China's sports industry. According to previous works, the existing sports training target detection system has the problem of nonlinear video and low target detection accuracy, which can easily cause target loss or tracking failure. Therefore, the Kalman Filter (KF) is studied in-depth and applied to detect the targets in sports videos. Combined with the Multi-Innovation (MI) theory, an MI-Extended KF (EKF) algorithm model based on nonlinear dynamic technology is proposed. This model can effectively solve the filtering accuracy problem under the strong nonlinear system. Finally, the performance analysis through different datasets has verified the effectiveness of the model proposed further. Results demonstrate that the model proposed can effectively improve the filtering accuracy of nonlinear systems. As the angle module changes, the accuracy of sports recognition also changes. The final accuracy of the model proposed can reach above 96%. The simulation results and convergence are better than other algorithms, which also proves the effectiveness of the model proposed. The results can provide a theoretical basis for the research related to the detection of training sports targets in sports videos. [ABSTRACT FROM AUTHOR]

Face slab concrete suffers from serious frost damage in the cold regions in China. How to improve the frost resistance of face slab concrete in cold regions is one of the important issues in concrete-faced rockfill dam (CFRD) design and construction. The results in this paper indicate that the frost resistance of concrete can be improved by adding fly ash, fiber, MgO and shrinkage-reducing admixtures (SRAs), and their efficiencies are in the following sequence: (fly ash + fiber) > fiber > fly ash > MgO > SRA. The incorporation of 0.8 kg/m3 polyvinyl alcohol (PVA) fiber and 20 wt.% fly ash together enhances the compressive strength and tensile capacity of concrete by 6–7% at the late age, whereas the addition of 6 wt.% MgO or 1 wt.% SRA reduces the compressive strength and tensile capacity by about 4–10% at various ages. The D s of concrete added with fly ash, fiber, MgO and SRA is within the range of 2.619–2.796. The frost resistance of concrete correlates linearly with the air void parameters, pore structures and D s . The utilization of fly ash and/or PVA fiber refines and optimizes the pore structure, thus increasing D s and improving the frost resistance. On the contrary, MgO and SRA in this study are less effective in refining the pores than PVA fiber and fly ash, thereby producing smaller D s and relatively weaker frost resistance. [ABSTRACT FROM AUTHOR]

This paper presents a numerical study on the equivalent permeability of a fractured rock. A series of two-dimensional discrete fracture network (DFN) models for the calculation of equivalent permeability are generated based on discrete element method (DEM). A sufficient large "parent" DFN model is generated based on the data obtained from a site investigation result of Three Gorges Project in China. Smaller DFN models are extracted from the large "parent" DFN model to calculate the equivalent permeability with an interval of rotation angle of 1 5 ∘ . Fluid flow through fractures in both horizontal and vertical directions is simulated. The results show that when the side length of DFN models are larger than 40 m, the equivalent permeability of both k x and k y become stable, indicating that a DFN model size of 40 m can be approximated as a representative elementary volume (REV) for those studied rocks. Penetration ellipses are fitted using the least square method on the basis of the calculated equivalent permeability tensor and the main seepage directions of this fractured rock were determined as 63–67 ∘ . Fractal characteristics of DFN models are analyzed with box-counting method by changing the fracture trace length and fracture density, and the results show that equivalent permeability exhibits a logarithmic increasing trend with the increment of fractal dimension. [ABSTRACT FROM AUTHOR]

In this paper, in a case study of Santanghu Basin in China, the morphological characteristics and size distribution of nanoscale pores in the volcanic rocks of the Haerjiawu Formation were investigated using the results of low temperature nitrogen adsorption experiments. This research showed that within the target layer, a large number of nanoscale, eroded pores showed an 'ink bottle' morphology with narrow pore mouths and wide bodies. The fractal dimension of pores increases gradually with increasing depth. Moreover, as fractal dimension increases, BET-specific surface area gradually increases, average pore diameter decreases and total pore volume gradually increases. The deeper burial of the Haerjiawu volcanic rocks in the Santanghu Basin leads to more intense erosion by organic acids derived from the basin's source rocks. Furthermore, the internal surface roughness of these corrosion pores results in poor connectivity. As stated above, the corrosion process is directly related to the organic acids generated by the source rock of the interbedded volcanic rocks. The deeper the reservoir, the more the organic acids being released from the source rock. However, due to the fact that the Haerjiawu volcanic rocks are tight reservoirs and have complicated pore-throat systems, while organic acids dissolve unstable minerals such as feldspars which improve the effective reservoir space; the dissolution of feldspars results in the formation of new minerals, which cannot be expelled from the tight reservoirs. They are instead precipitated in the fine pore throats, thereby reducing pore connectivity, while enhancing reservoir micro-preservation conditions. [ABSTRACT FROM AUTHOR]

In order to better understand the impact of fractal features of pore-throat structures on effective physical properties of tight gas sandstones, this paper carried out constant-rate mercury injection tests, gas-water permeability analyses, helium-based porosity and nitrogen pulse decay permeability measurements, and SEM and casting thin-section analyses on 20 sandstone samples of the Shihezi Formation from 16 wells of the Sulige Gas Field in the Ordos Basin, China. The fractal dimensions of pores corresponding to two pore radius ranges, namely fractal dimensions and , and those of throats also corresponding to two throat radius ranges, namely fractal dimensions and , were then calculated using the constant-rate mercury injection data. Fractal dimensions and are negatively correlated with the average pore radius and pore volume as well as quartz content, and they are positively related to contents of clay minerals and lithic fragments. Compared with pore fractal dimensions, throat fractal dimensions have lower correlations with throat structural parameters, and show vague relations with mineral compositions. Although the effects imposed by mineral compositions upon throat structures are similar to those upon pore structures, the flake-like and curved shapes of throats result in irregularity of fractal dimensions. Tight gas sandstones, with smaller fractal dimensions and , have larger effective porosity, indicating that more gas volumes can be replaced by liquids. As for tight gas sandstones with lower fractal dimensions and , the effective gas permeability is relatively high. In such cases, gas can flow more easily through the reservoir. [ABSTRACT FROM AUTHOR]