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Stereolithographic three-dimensional (3D) printing of metals is a new additive manufacturing technology. The metal parts prepared by this technology have the characteristics of complex shape and precise structure, and no post-processing is required. It is an advanced manufacturing technology that has enormous potential in fabricating complex parts owing to the considerable progress of stereolithography, digital light processing, liquid crystal displays, continuous liquid interface production, and two-photon polymerization in recent years. This paper summarizes the current research progress on stereolithographic 3D printing of metals and defines four major methodologies, namely, curing sintering, curing coating, mixed curing, and curing mold. Of these, the curing sintering method is the primary technique to prepare metal parts by mixing metal powder with photosensitive resin and forming parts through degreasing and sintering at high temperatures. In curing coating, a metal film is coated on the surface of a solidified resin matrix, which is often used to prepare precision electromagnetic equipment. The mixed curing process is used to directly cure metal slurry without sintering to complete the one-step formation of parts. The curing mold technique is used to realize the multistep formation of parts by using the resin matrix or the ceramic matrix as the mold, followed by subsequent treatments such as casting. In this review, the composition of metal slurry and the resulting properties of the stereolithographic 3D printed metal parts are summarized. Key scientific questions on the property difference between metals and polymer in the slurry, immature processing parameters, lack of reliable compositions for photosensitive resin are still unresolved. The direction of future development is forecasted by studying on the influence of process parameters on the performance of parts, on the new formulas of photosensitive resin, and on more suitable equipment for the stereolithographic 3D printing of metals.

In order to improve the recognition accuracy of coal vitrinite macerals and performance of recognition model, reduce the manual intervention in the training of recognition model, a lightweight deep learning network model for coal vitrinite submaceral recognition, which is embedded with an improved attention mechanism, is proposed. Firstly, aiming at the problem of small amount of vitrinite sample data, a data enhancement method of random clipping, rotating, mirroring and noise adding is employed to enhance the original sample data and improve the generalization ability of the recognition model. Then, a backbone network is constructed based on the ShuffleNet V2 model pre-trained on a large data set ImageNet. A transfer learning method, which freezes some layers near the input and adjust the weight parameters of layers near the output of the pre-trained model according the enhanced training sample set of vitrinite microscopic image, is employed to generate some deep feature extraction layers. Finally, a channel attention mechanism ECA, which is improved according to the characteristics of distinct texture feature of vitrinite microscopic image, is embedded before the output of the ShuffleNet V2 model, and a new lightweight end-to-end recognition network model is constructed to implement the automatic recognition of seven submacerals of coal vitrinite. The experimental results show that the average recognition accuracy of submacerals with this method can reach 97.85%, gone beyond 5.71% of the original ShuffleNet V2 model. Compared with the classical neural network, the proposed model has higher accuracy, lesser number of parameters and calculation, and rapid convergence velocity. Compared with other lightweight networks and other attention embedding mechanisms, the proposed network not only maintains a less amount of parameters, but also significantly improves the recognition accuracy.

Taking the main bearing-main journal of a six-cylinder diesel engine as the research object，based on the elastic- -fluid lubrication theory and the micro-bump contact theory and considering factors such as journal misalignment and main bearing surface roughness，the main bearing lubrication characteristics model under the flexible whole body is established，and the influence of the main bearing surface profile on the main bearing lubrication characteristics and main journal vibration characteristics is analyzed. The results show that，compared with the result that does not take into account the main bearing surface profile，when the main bearing surface profile is included，the minimum oil film thickness of the main bearing is increased by 75.53%，the maximum oil film pressure is reduced by 6.15%，the average friction loss is reduced by 2%，the horizontal flexural vibration amplitudes of the main journal is reduced by 6%，the vertical flexural vibration amplitudes is reduced by 5%，and both the axial vibration and torsional vibration amplitudes are reduced by 2%. With the increase of the main bearing surface profile height，the minimum oil film thickness of the main bearing increases，the maximum oil film pressure decreases，the average friction loss decreases，and both the maximum roughness contact force amplitude and the number of occurrences are reduced; the amplitudes of flexural vibration，axial vibration and torsional vibration of the main journal are all reduced.

With the continuous development of social economy and the rapid progress in science and technology, the three-dimensional multilayer usufruct of sea areas has become an effective way to fulfil the increasing marine usage activities in China. However, this pattern has put forward higher demands for the spatial scope definition and ownership management of sea areas. This paper analyzed the connotation, basic principles and consideration factors of multilayer usufruct of sea areas based on the nature of stratification in three-dimensional space of sea areas, and the difficulties in the development and utilization of three-dimensional space of sea areas and the design of the associated management system were comprehensively discussed. Research results showed that the sea area space could be divided into five parts: above the water surface, water surface, water body, seabed and subsoil. The three-dimensional multilayer usufruct of sea areas was the process of confirming the right to use the specific sea space occupied by specific functional purposes in the multi-level use of the same sea area. A legal system of three-dimensional property rights in sea space should be constructed and improved to ensure the implementation of three-dimensional multilayer usufruct of sea areas.

Genetic variation is one of the important factors leading to the incidence and development of cancer. Copy number variation is an important source of genetic diversity， which can be expressed as gene amplification or deletion in structure， and is related to the occurrence and development of different tumors. High-throughput sequencing and gene chip technology can be adopted to detect the variation of copy number， and provide relevant information about tumor molecular characteristics， prognosis and treatment， which is conducive to more accurate diagnosis and treatment decisions for patients in clinical practice. Ovarian cancer is one of the female reproductive system diseases with the highest mortality rate. Understanding its pathogenesis is of significance for improving the survival rate of ovarian cancer. At present， the specific role and mechanism of copy number variation in ovarian cancer are still unclear. In this article， relevant copy number variation in ovarian cancer was reviewed based on the existing research results， aiming to provide novel ideas and methods for the prevention， diagnosis and treatment of ovarian cancer.