m采高采煤机牵引箱加载试验分析

为了满足9 m采高特厚煤层综采要求,设计了MG1100/3050-WD采煤机。鉴于新牵引箱的结构和参数,选择了倒置的加载方式。采用液压加载试验台进行热平衡试验,并对试验结果进行了分析,满足空载试验和热平衡试验标准和要求。此牵引箱达到型式试验要求,可以出厂进行工业性试验。     

铝合金拐臂盒件铸造工艺优化

铝合金拐臂盒铸件轴孔处容易产生缩松缺陷,对此进行了原因分析和工艺改进。依据铸造凝固理论结合实际生产经验,采用不同热导率的金属材料的冷铁及增加工艺补贴等方法,对铸造工艺进行优化。优化后经过X光无损检测及机加工验证,成功解决了轴孔处缩松的铸造缺陷。     

遗传算法和模矢法结合的概率积分法参数反演方法

遗传算法在反演概率积分法预计参数时从参数取值范围内的串集开始搜索,并使用弹性策略来维持群体的多样性,使得算法可以跨过局部收敛的障碍,向全局最优解方向进化;但这种概率化的寻优算法存在局部探索能力差、结果不稳定的缺陷,只能获得问题的近似最优解。模矢法是一种降梯度算法,算法局部探索能力强、收敛快;但这种算法对初值选取敏感,初值选择不当易陷入局部极值。本文提出并实现了一种模矢法与遗传算法结合的组合算法:先使用遗传算法求得参数的全局近似最优解,然后将近似最优解作为探索初值,使用模矢法获得参数的稳定、精确最优解。研究结果表明:组合算法反演概率积分法预计参数的精确度高、收敛快、稳定性好,综合性能较遗传算法和模矢法有明显优势。     

On the performance of improved quadrature spatial modulation

Quadrature spatial modulation (QSM) utilizes the in‐phase and quadrature spatial dimensions to transmit the real and imaginary parts of a single signal symbol, respectively. The improved QSM (IQSM) transmits two signal symbols per channel use through a combination of two antennas for each of the real and imaginary parts. The main contributions of this study can be summarized as follows. First, we derive an upper bound for the error performance of the IQSM. We then design constellation sets that minimize the error performance of the IQSM for several system configurations. Second, we propose a double QSM (DQSM) that transmits the real and imaginary parts of two signal symbols through any available transmit antennas. Finally, we propose a parallel IQSM (PIQSM) that splits the antenna set into equal subsets and performs IQSM within each subset using the same two signal symbols. Simulation results demonstrate that the proposed constellations significantly outperform conventional constellations. Additionally, DQSM and PIQSM provide a performance similar to that of IQSM while requiring a smaller number of transmit antennas and outperform IQSM with the same number of transmit antennas.     

一种新型包装专用蜡的研制

为了根据某瓦楞纸箱生产厂的实际生产条件制备一种耐热、耐低温、防水、透气等性能优异的包装专用蜡，将58号全炼蜡和70号微晶蜡混合物作为基础蜡料，分别考察添加剂、助剂、抗氧剂等对基础蜡料滴熔点、运动黏度及外观等的影响，确定了最佳制备配方：合成蜡、添加剂B、助剂1、助剂2、抗氧剂加入量（w）分别为基础蜡料质量的9.8%，6.5%，1.5%，2.1%，0.1%。在温度为160 ℃、时间为30 min、搅拌速率为200 r/min条件下制备的包装专用蜡具有熔点高、黏附性强、光泽性好的优点，满足该瓦楞纸箱生产厂的质量和外观要求。     

高速齿轮箱迷宫密封泄漏量正交仿真试验优化

以某型号高速动车组传动齿轮箱大齿轮电机端的迷宫密封结构为研究对象,运用Fluent建立带有扩散空腔的迷宫密封二维轴对称有旋流动模型,对迷宫密封泄漏量进行模拟仿真,指出现有结构存在密封间隙略大、齿顶角度较大、空腔深度较浅的不足。采用Design-expert 8.0软件设计仿真方案,通过分析密封间隙、齿形角度、密封齿数、密封空腔深度及传动轴转速对迷宫密封泄漏量的影响,得到一组使泄漏量最低的最优参数。结果表明:单因素对迷宫密封泄漏量影响的强弱顺序依次为密封间隙、空腔深度、齿数、角度,转速对泄漏量几乎没有影响;交互作用影响因素中,密封间隙和空腔深度对泄漏量影响大于密封间隙和齿数。通过重新建模仿真验证了利用Design-Expert 8.0软件设计迷宫密封泄漏量仿真试验方案和进行迷宫密封参数优化是可行的。     

Ship length distribution modeling on China offshore and ability evaluation of radar ship classification

Radial size estimation using radar high-resolution range profiles(HRRPs) and heading angle estimation are the main means for ship classification.The classification ability is closely related to the range resolution of the radar,precision of radial size estimation,and prior distribution of ship lengths in different offshore areas.We collected the AIS information on about 30 000 ships and their lengths in the four offshore areas of China in the ship information net of China.By fitting the data of ship lengths in each offshore area,it is found that the Weibull distributions provide good-of-fitness to the ship lengths and the parameters in individual area are rather different.Based on the prior distributions of ship lengths,we derived the quantitative relationship between the correct classification probability of big-moderate-small ships and the estimate error of ship radial size.The results indicate that the condition for the big-moderate-small correct classification probability in the offshore areas of China to be up to 90% is that the estimate errors of the ship radial size estimates falls into the interval(-12.67 m,9.41 m) when the heading angle of the ship is between ±75 degrees.     

Multi-task learning for video anomaly detection

We propose a multi-task learning framework for video anomaly detection based on a novel pipeline. Our model contains two crossing streams, one stream employs the backbone of Attention-R2U-net for future frame prediction, while the other is designed based on an encoder–decoder network to reconstruct the input optical flow maps. In addition, the latent layers of the two streams are merged together and assigned with a Deep SVDD-based loss at each location individually. Through the combination of these three tasks, the two-stream-crossing pipeline can be trained end-to-end to provide a comprehensive evaluation for the anomaly targets. Experimental results on several popular benchmark datasets show that our model outperforms the state-of-the-art competing models, which can be applied to different types of anomalous targets and meanwhile achieves remarkable precision.