摘要：目的研究振动式粒度仪的振动频率、 振幅等因素对石英砂颗粒和河沙颗粒筛分效率的影响。方法设计一款小型多层圆形振动式粒度仪，使用Rocky DEM仿真软件模拟振动式粒度仪筛分石英砂颗粒和河沙颗粒的过程； 通过调节粒度仪振动筛分装置的振幅、 频率等参数，计算在一定时间内不同筛分振幅和频率下颗粒的筛分效率； 最后通过实验对2种颗粒的筛分效率进行测试。结果振动频率为75~105 Hz、 振动幅度为0.1~0.2 mm时石英砂颗粒和河沙颗粒的筛分效率最高； 在仿真结果最优频率及幅值范围内，该振动筛分装置的效率较高，对2种颗粒的筛分效率均大于90%。结论研究小型多层圆形振动筛分装置的筛分效率，能够有效缩短振动式粒度仪筛分的时间且达到更高的筛分效率，避免振动筛分装置的筛分效率低导致的能源浪费。

摘要：Two-dimensional(2 D)van der Waals materials have been widely adopted as photocatalysts for water splitting,but the energy conversion efficiency remains *** the basis of first-principles calculations,we demonstrate that the 2 D Janus group-Ⅲchalcogenide multilayers:In Ga XY,M2XY and In GaX2(M=In/Ga;X,Y=S/Se/Te),are promising photocatalysts for highly-efficient overall water *** intrinsic electric field enhances the spatial separations of photogenerated carriers and alters the band alignment,which is more pronounced compared with the Janus *** solar-to-hydrogen(STH)efficiency with the upper limit of 38.5%was predicted in the Janus *** excitingly,the Ga vacancy of In Ga SSe bilayer effectively lowers the overpotentials of hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)to the levels provided solely by the photogenerated *** theoretical results suggest that the 2 D Janus group-III chalcogenide multilayers could be utilized as highly efficient photocatalysts for overall water splitting without the needs of sacrificial reagents.

摘要：Multifunctional catalysts that integrate high efficiency hydrogen evolution reaction(HER), oxygen evolution reaction(OER) and oxygen reduction reaction(ORR) catalytic activity in a single material are attractive for unitized regenerative fuel cells and overall water splitting technologies. As the best-known HER and ORR electrocatalysts, Pt and its alloys have only moderate OER activity. Ruthenium and iridium oxides exhibit the highest OER activities but not as active as Pt for HER and ORR. Here, we proposed a general principle for achieving trifunctional electrocatalysis for three reactions in a single material. Using the newly-synthesized pyrazine-modified graphdiyne(PR-GDY) as an example, we demonstrated that the synergistic effect of the pyridinic nitrogen and anchored transition-metal(TM) single atoms renders highly-efficient HER/OER/ORR trifunctional electrocatalytic activity. For the Ni-doped PR-GDY, the overpotentials for HER, OER and ORR can be respectively as low as -0.05, 0.29 and 0.38 V, which are comparable or even superior to the best-known single-functional and bi-functional precious *** computational results offer not only a promising trifunctional electrocatalyst but also a strategy for the design of multifunctional electrocatalysts.

摘要：脑室穿刺引流手术是颅脑损伤急救的重要手段。但该术式存在颅骨开孔费时费力、有经验医师缺乏时难以实施等问题。为了简化急救流程、降低急救手术要求,研制了图像引导下的遥操作脑室穿刺手术机器人系统。该系统包括遥操作穿刺执行器系统、机械臂、术前规划系统和视觉导航系统。采用压力传感器差分式布局设计基于EtherCAT总线的颅骨穿刺执行器;使用基于B样条变换的可变性配准在CT、MR融合图像上进行手术规划和视觉导航;在双目视觉引导下使7自由度冗余机械臂按照术前规划的路径以指定的姿态定位颅骨穿刺执行器到起始位置;采用人在环操作模式,使用视觉化工具函式库(VTK)对操作可视化,在视觉与力觉双重反馈下进行颅骨穿刺。针对3D打印颅骨模型进行穿刺实验,表明机器人穿刺误差为0.74 mm;针对一条比格犬进行动物实验,表明穿刺误差1.22 mm,与经验丰富的急救医生操作精度相当,表明该机器人有一定的临床应用潜力。

摘要：对于穿越城市中心区域的主要干道,集约并妥善处理好过境交通与片区交通的关系,关乎到整个通道交通转换的效率,而其中交通组织方式的选择往往由城市景观、周边环境协调性、规划协调性、工程造价等多因素综合确定的。介绍厦门翔安大桥在本岛侧枋钟路特定的控制因素下,通过多因素对长隧道、短隧道及高架等方案进行综合比选,进而确定合适的交通组织方式。研究成果为类似项目的方案分析与选择等提供了技术支持及实践依据。

摘要：林木良种生产是“林木遗传育种学”课程的重要实践内容。利用现代信息技术,开展林木良种多圃配套育苗技术虚拟仿真实验教学对于“林木遗传育种学”实验教学体系完善、林学一流学科建设和现代林木种业创新人才培养具有重要意义。文章系统阐述了北京林业大学林木遗传育种教学团队开发的“林木良种多圃配套育苗技术虚拟仿真实验教学系统”的总体架构,从专业知识的设计、虚拟场景的搭建、人机交互的构建、教学成效及系统使用反馈体系的建设方面总结了虚拟仿真实验教学系统的设计思路,并对持续开展林木遗传育种学虚拟仿真实验教学体系建设提出建议,从而为林业领域更多虚拟仿真实验教学项目建设提供借鉴,服务林学一流学科建设。

摘要：作品设计思路、实现和制作计划通过Micro:bit的无线功能,实现手环与救助站之间的数据传输。手环包括一个Micro:bit和供电模块,增加按钮和北斗芯片,通过北斗芯片实现位置信息的获取,按下按钮发送信息。救助站包括一个Micro:bit和供电模块,增加数码管、OLED屏幕,用于显示数据,使用WS-2812单RGB灯实现频闪灯光提示,通过喇叭实现快速的声音提示。