分类： 机械工程 >> 机械设计 提交时间： 2024-04-01
摘要： Overstaffing production in underground coal mining is not convenient for daily management, and incomplete information of coal miners hinders the rescue process of firefighters during mine accidents. To address this safety sustainability issue, a novel face recognition method based on an improved multiscale neural network is proposed in this paper. A new depthwise seperable (DS)-inception block is designed and a joint supervised loss function based on center loss theory is developed to constructe a new multiscale model. The miniers can be recognized in the harsh underground environment during the life rescue. Experimental results show that the accuracy, recall and F1-score indexes of the proposed method for the miner face recognition in the underground mining environment are 97.26%, 94.17% and 95.42%, respectively. Transfer model with joint supervised loss can effectively improve the recognition accuracy by about 0.5~1.5%. In addition, the average recognition accuracy of the proposed face recognition method achieves to 91.34% and the miss detection rate is less than 5% in the dugout tunnel of coal mine.
分类： 机械工程 >> 机械设计 提交时间： 2024-03-31
摘要： The bottom pivot is a vital support device in the miter gate but often subject to poor lubrication and wear failures. Calculating thehydrodynamic lubricationcharacteristics of the bottom pivot is a complex three-dimensional (3D) problem, and most of existing models adopt simplified assumptions to reduce the calculation difficulty. To solve this issue, this work develops a 3D model to calculate thehydrodynamic lubricationcharacteristics of the miter gate bottom pivot. Thefinite difference methodis used to solve theoil film thicknessand pressure distribution based on the spherical coordinatesReynolds equation. The component forces in three directions are calculated from the pressure distribution and compared with the theoretical values to generate the calculation difference. Then, thegenetic algorithm(GA) is used to minimize the difference to determine the optimal initial parameters for the 3D model. The analysis results show that the calculation accuracy can be significantly improved by using the optimal initial model parameters. When our initial pressure is 5.64MPa, the results meet the engineering accuracy requirements.
分类： 机械工程 >> 机械设计 提交时间： 2021-11-17
摘要： The biomimetic design provides an adequate solution to achieve an excellent design. However, the prototype space for biomimetic design is relatively large, and it becomes more and more challenging to find the required biological prototypes quickly and efficiently. In order to improve the design efficiency and enrich the means of biomimetic innovation, this paper proposes a biological knowledge-enabled bidirectional encoder representation from transformers (BERT) model to assist biomimetic design, namely BioDesign. We extract the biological strategies, functions and extract dimensional information from the Asknature as the data source. The linguistic expression model-BERT was used to recommend biomimetic strategies or functions combined with the biological strategies data. Finally, we take the biomimetic erosion wear resistant design of the valve core as an example and use the proposed BioDesign model to recommend biomimetic inspired functions. According to the recommended content of the BioDesign model, we obtained the erosion wear resistance strategies and designed the biomimetic structure. The erosion wear experiment proved the feasibility and effectiveness of the proposed method.
分类： 机械工程 >> 机械设计 提交时间： 2018-03-14
摘要： Precision reducer is one of the key parts of an industrial robot, which generally incorporates cycloidal planetary drive. Engagement of the cycloidal wheel and the pins causes rolling friction between the wheel and the pins as well as sliding friction between the pins and the pin housing in the traditional cycloidal transmission of the reducer. In this paper, we present a new kind of design to make the pins and the pin housing a whole structure, thereby the cost of manufacturing and assembly can be significantly reduced. And in this new structure, we only need to consider sliding friction between the cycloidal wheel and the unibody of the pins and pin housing. The difference between the new structure and the conventional structure in the meshing properties was given. In addition, we used finite element method to analyze the friction and contact stress between the cycloidal wheel and the pins in the actual working condition, and compared it with the traditional structure. The simulation results proved the feasibility of the new structure and provided a theoretical basis for further design and manufacturing of this new kind of cycloidal planetary drive structure.
分类： 机械工程 >> 机械设计 提交时间： 2018-03-14
摘要： 摆线行星传动通常通过摆线轮与针轮相啮合，以实现传动。摆线轮的轮廓一般是摆线。本文介绍了摆线传动的两种类型，一种是外摆线的内偏置，另一种是内摆线的外部偏移。在AutoCAD中构造了两种类型的三维模型。利用机械系统动力学仿真技术进行动力学仿真，并通过运动曲线验证了动力学模型的正确性。计算了两种类型摆线轮与针齿之间的动态啮合力，并对传动特性进行了比较。实验结果表明，内摆线传动能产生更稳定的输出速度，并能降低啮合力。
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