Electro-optic Q switch of an La3Ga5SiO14 crystal

We study the influence of the electro-optic and optical activity effects of a crystal on the arbitrary linearly polarized light propagating along the optical axis and design an experiment to demonstrate this. According to the theory and the experimental results, we achieve a successful voltage-decreased electro-optic Q switch of the La3Ga5SiO14 crystal.     

原子力显微镜测量杨木细胞特征参数

在微/纳米尺度下原子力显微镜已成为研究木质材料的重要工具。本文基于原子力显微镜对速生杨木细胞的特征参数进行测量。结果表明:利用原子力显微镜,完全可以在微/纳米尺度下对速生杨木的细胞形态特征进行测量;杨木细胞横截面的导管壁厚平均尺寸为2.230 μ m;木纤维壁厚平均为2.044 μ m,壁长平均为9.498μm;细胞外径平均为19.723 μ m。     

通用型交流伺服驱动器设计技术探讨

介绍了通用变频器、交流永磁同步伺服驱动器和交流异步伺服驱动器在数控机床行业的应用现状;提出并阐述了交流伺服驱动器使用的统一型硬件平台的设计特点和技术要点;通过对永磁同步电动机和感应电动机的磁场定向矢量控制算法的异同点分析,提出了设计通用型交流伺服驱动器的一种合理的控制算法架构;在吸收软件工程中面向对象编程思想的基础上,设计了一种适合于团队开发的高效的控制软件开发模型.     

Influence of La2O3 addition on nano indentation hardness and residual stress of Stellite 6 coating prepared by plasma cladding

One of the problems limiting the application of Stellite 6 coating is the residual stress resulting in cracks in the coating easily. In order to reduce the residual stress and increase the nano-indentation hardness, La₂O₃ was added to Stellite 6 coating in this study, and the influence on the microstructure, nano indentation hardness and residual stress of the coatings were investigated by scanning electron microscopy (SEM) with energy dispersive spectrum (EDS), X-ray diffraction (XRD) and nano-indentation tester. Results indicate that the addition of La₂O₃ leads to the phenomenon that the dendrite is partly transformed into the equiaxed grain, which results in the grain refinement. The nano-indentation hardness of coatings is improved, which is attributed to the fine-grain strengthening and dispersion strengthening effect of La₂O₃. With the addition of La₂O₃, the residual stress in coatings is decreased significantly. Especially, when the content of La₂O₃ is 0.8 wt%, the nano indentation hardness increases by 1.31 times and residual stress decreases to 20 percent, compared with coating without La₂O₃.     

向后筛选策略在鄂尔多斯盆地三叠系延长组储层微观非均质性评价中的应用

鄂尔多斯盆地华庆地区三叠系延长组6段（长6段）和合水地区长8段储层成岩作用改造强烈,孔喉结构复杂,微观非均质性强。为更好地定量表征储层微观非均质性,对前人提出的储层微观非均质性评价参数进行了重新厘定。采用向后筛选策略,针对华庆地区长6段储层利用前人提出的相关参数建立回归方程,提出综合评价参数N,针对合水地区长8段储层利用高压压汞相关参数建立回归方程,提出参数G_k和G_s,定量综合评价储层微观非均质性,同时验证向后筛选策略在解决地质问题上的可行性。结果表明：综合评价参数N与渗透率具有较好的相关性,将储层微观非均质性分为强、中等、弱,相关系数分别为0.981 2,0.949 6和0.772 4,G_k与孔隙度、G_s与渗透率也都呈现较好的相关性。3个综合评价参数较单一评价因素相关性均有明显提高,说明向后筛选策略在储层微观非均质性定量评价方面取得了较好的结果,表明数学方法可以为相关地质问题的解决提供新的途径。     

房屋建筑砌体结构施工技术

在建筑物施工的进程中,砌体施工的状况直接影响工程的质量。它在施工过程总占据举足轻重的地位。本文主要是在以砌体施工为关键的前提下,描述了施工前的贮备工作、各阶段的工艺流程、施工中对砌体的质量要求和标准要求。     

Efficient force prediction for incremental sheet forming and experimental validation

Incremental sheet forming (ISF) has been attractive during the last decades because of its greater flexibility, increased formability and reduced forming forces. However, traditional finite element simulation used for force prediction is significantly time consuming. This study aims to provide an efficient analytical model for tangential force prediction. In the present work, forces during the cone-forming process with different wall angles and step-down sizes are recorded experimentally. Different force trends are identified and discussed with reference to different deformation mechanisms. An efficient model is proposed based on the energy method to study the deformation zone in a cone-forming process. The effects of deformation modes from shear, bending and stretching are taken into account separately by two sub-models. The final predicted tangential forces are compared with the experimental results which show an average error of 6 and 11 % in respect to the variation of step-down size and wall angle in the explored limits, respectively. The proposed model would greatly improve the prediction efficiency of forming force and benefit both the design and forming process.     

地下电站异型洞室开挖测量方法探讨

介绍了地下电站工程中不同部位的控制网布设及贯通测量方法,并针对异型洞室提出了高效、经济的测量放样方法和测绘成果整编思路。     

一个计算机系统抽象模型(AMCS)及其性能的研究

文章建立一个AMCS(AbstractModelofComputerSystem)模型,可作为研究单机系统、多机系统和计算机网络的一个统一模型,并进一步分析了这个AMCS模型的性能,推导出其表达式:Q=(α·p)/(ň·β·tψ)。这个公式表明了影响AMCS性能的因素和提高其性能的途径。     

改进YOLOv3-SPP水下目标检测研究

针对水下目标检测任务中图像模糊、背景复杂以及目标小而导致误检和漏检问题,提出一种改进YOLOv3-SPP的水下目标检测算法。利用UWGAN网络对水下原始图像进行恢复,采用Mixup方法增强数据,减少错误标签记忆;以YOLOv3-SPP网络结构为基础,增加网络预测尺度,提高小目标检测性能;引入CIoU边框回归损失,提高定位精度;利用K-Means++聚类算法,筛选最佳Anchor box。将改进YOLOv3-SPP算法在处理后的URPC数据集上进行实验,平均检测精度由79.58%提升到88.71%,速度为28.9 FPS。结果表明,改进算法综合检测能力优于其他算法。