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关键词： heat and mass transfer   thermal comfort   operating room   LAF system   human body   validation  

摘要： Air velocity and temperature distributions inside operating rooms (ORs) play a crucial role to reduce the risk of infections and to ensure adequate comfort conditions for patient and medical staff. In this work, the authors have developed a three-dimensional thermo-fluid dynamic model to simulate airflow and thermal comfort in an actual OR equipped with High-Efficiency Particulate Air (HEPA) filters. The model takes into account the presence of surgical lights, people and equipment within the room. An experimental campaign is carried out inside the actual OR to measure velocity and temperature, to be employed as boundary conditions for the numerical model. The experimental data have also been used to validate the numerical results. The validated model has been used to analyze the effects of human shape, thermal boundary conditions and buoyancy forces on the main thermal and fluid dynamic quantities in the OR. The thermal comfort is evaluated based on Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD) indices. The results prove that the present experimental-numerical approach is useful to analyze and improve the thermal comfort conditions for medical staff and patient.

关键词： 汽车设计   汽车密封条技术   ANSYS有限元非线性  

摘要： 本文借助某车型车门密封条作为实际案例,基于有限元分析ANSYS软件使用非线性化有限元计算,针对密封条进行有效深层次探究,并且将密封条压缩负荷限制到(3±0.5)N范围当中,进而实现满足汽车密封条相关标准要求。

关键词： 小功率   中波发射机   天线系统   自动调谐器   工作原理  

摘要： 基于科技的飞速发展,中波发射机的应用受到人们的重视,也彰显出中波发射机的重要价值。为保证小功率中波发射机天系统可以做到稳定和安全的运行,工作人员需要对自动调谐器的工作原理进行深入分析,将系统的应有效用充分发挥,从而将值机人员原有的工作压力做到逐步减轻,将工作效率不断提升。基于此,本文对小功率中波发射机天线系统自动调谐器的使用价值进行多角度分析,简述其工作原理,探讨参数检测电路的设计,力求保证系统运行的长效性与稳定性。

关键词： 区域推进   顶层设计   打造学习空间  

摘要： 黄浦区作为在上海市率先开展小学低年级主题式综合活动课程整体试点区域,在实践过程中坚持理念先行,做好顶层设计,开辟了区块链一体、教科研联动、全课程融通、校本化实施、多平台共享等五大实施路径,打造了“充满童趣”的学习空间,形成了行之有效的经验。

关键词： 理论力学   材料力学   结构力学   教学内容   教学方法   考核方式  

摘要： 安徽新华学院是安徽省地方民办高校,办学宗旨是培养适应地方建设的应用型人才[1]。力学课程是土木工程专业学生的专业基础课,学生在大学期间需要学习三大力学课程——理论力学、材料力学和结构力学。该文论述了安徽新华学院下属二级学院城市建设学院近几年关于力学课程教学的一些改良做法,以期为相关专业课程体系的建设和改革提供参考。

关键词： NEURAL-NETWORKS   SECONDARY VOLTAGE   COMPLEX NETWORKS   MIXED DELAYS   TIME-DELAY   SYNCHRONIZATION   OSCILLATORS   INVERTERS  

摘要： In this paper, the global stability of coupled control systems (CCSs) is discussed. Assembling the energy of each vertex system with the help of graph theory, a systematic method for constructing a global Lyapunov function of CCSs is proposed. Then, two kinds of stability criteria by Lyapunov-type theorem and coefficient-type theorem with the condition of the system topology are derived. Subsequently, the theoretical results are applied to the microgrid and the criterion of global asymptotical stability of the microgrid is developed. Meanwhile, based on the actual demand of the microgrid, the secondary frequency distributed consistency sliding mode control of the microgrid is proposed using the consensus algorithm. In the presence of a time-varying load, the control can not only quickly stabilize the frequency at the equilibrium point but also dynamically achieve active power sharing. Finally, the simulation of an islanded microgrid is conducted to test the validity and feasibility of our results. (C) 2021 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.

关键词： MOOC   在线开放课程   总结   反思  

摘要： 在“互联网+”的技术背景下,大规模在线开放课程建设成为教育模式变革的重要途径。目前基于此主题的研究,主要集中于教学模式与教学方法、学习满意度影响因素和学习过程及其问题三个方面。反思目前在线开放课程的建设状况,学界需注重学生对在线开放课程教学的认知调研、教师设计与组织在线开放课程的教学方法及效果的分类分析、成绩评定方式以及MOOC状态下师生互动的研讨与创新,对这些方面的深刻认知,必将推动MOOC在线开放课程的进一步发展。

关键词： 太阳能   理想抛物面   实际镜面   聚光集热系统   光学性能  

摘要： 为了解实际镜面布置细节对碟式聚光集热系统光学性能的影响,通过TracePro对系统进行光学模拟,对比分析了聚光镜为理想抛物面镜面与实际镜面时碟式聚光集热系统的光学性能。模拟结果表明:采光口与聚光镜焦点的距离S=-100~100 mm时,实际镜面布置细节对光学效率几乎无影响;S=0~140 mm时,实际镜面布置细节降低了盘管吸收比例,并会显著削弱腔体底面圆板与盘管表面热流密度分布的均匀性。本文的研究得到了更准确的光学性能,可供吸热器传热性能研究参考。