The Influence of Hygroscopic Materials on the Fluctuation of Relative Humidity in Museums Located in Historical Buildings

ABSTRACT

The preservation of artefacts in museum collections is profoundly affected by fluctuations in temperature and, especially, relative humidity (RH). Since the late nineteenth century, many studies have been carried out on the best way to control hygrothermal conditions. In old buildings located in maritime temperate climate zones (such as Portugal) with strong thermal inertia, and which have low ventilation rate (relative to the volume and number of visitors), daily and seasonal hygroscopic inertia may help to assure the maintenance of RH stabilization conditions. The use of expensive active systems may be minimized through the passive behaviour of internal finishing building materials. This work presents the results of an experimental laboratory study conducted in a flow chamber to demonstrate the enormous potential of hygroscopic materials in stabilizing interior relative humidity. Based in these results and in-situ monitoring in a museum housed in a building, located in Porto, with a typical construction of the 1950s (granite masonry and reinforced concrete slabs), a numerical analysis was done to quantify the influence of hygroscopic materials in stabilizing the interior relative humidity.     

人体惯性参数的实测生物力学研究

人体惯性参数是进行生物力学分析、人类工程学等工作时均需要的人体基本参数。通过活体的实际测量 ,比较中国人体惯性参数和国外人体惯性参数所计算人体总重心位置的差异 ,经统计学数据处理来验证中国人体惯性参数的可靠性 ,研究表明 :中国人体惯性参数比国外人体惯性参数更加适应中国情况 ,应对中国人体惯性参数推广应用     

滚翻垫球后“再后倒”现象的讨论

对滚翻垫球后“再后倒”现象进行理论分析 ,可找出出现问题的根源 ,以便在教学中解决这一问题     

论刚体对坐标轴转动惯量的平移和旋转变换

本文导出了刚体对坐标轴的转动惯量的平移和旋转变换一般式。     

陈序经的东西文化观新论

陈序经的文化观是他全盘西化论的理论基石。陈序经认为“文化是人类适应环境时代,以满足其生活的努力的结果和工具”,他还强调文化的世界性和中国文化的惰性。从文化的定义、文化的世界性、文化的惰性三方面对陈序经东西文化观进行考察,才能够真正理解其内心的苦衷,澄清人们的误解。     

伽利略的实验思想评述

伽利略善于运用理论思维指导实验选题,同时把实验和数学进行有机结合,依靠逻辑推理,并用实验来检验,构成一整套的实验科学方法.他设计的实验构思巧妙,蕴涵着丰富的实验思想,其卓越的实验思想及由此发展起来的物理学探索方法,为近代物理学奠定了基础.     

网络嵌入、知识惯性与双元创新能力 ——基于动态视角的评述

[目的/意义]网络嵌入和知识惯性对提升企业创新能力具有重要影响。[方法/过程]通过文献分析,针对网络嵌入及其演化特征对知识惯性的影响、知识惯性对双元创新能力的影响以及网络嵌入对双元创新能力的影响进行了系统梳理和评述。[结果/结论]总结提炼了3点结论,并在此基础上就如何充分利用网络嵌入的演化特征来调节知识惯性与双元创新能力间的关系,从动态视角提出了整合性理论框架以及进一步的研究思路与展望,不仅对深化该领域的研究具有理论与方法启示,同时对我国企业在动态网络下有效整合网络嵌入和知识惯性、提升双元创新能力具有重要现实指导意义。     

企业动态能力系统演化的状态变量与影响因素

在分析动态能力理论局限性的基础上,提出了一个企业动态能力系统的概念框架和基于系统动力学的仿真模型,并研究了相关问题.研究结果表明:(1)创造环境和共同进化是分析系统的逻辑起点,创造需求和新价值是系统的主要功能.(2)企业知识相关变量和企业资源相关变量是系统演化的主要状态变量,学习投入率、学习效率、价值匹配程度是系统演化的主要驱动因素,组织思维惯性和组织行为惯性是系统演化的主要限制因素.这四个参数变量决定了系统演化的路径.(3)引导顾客及其它商业生态网成员参与知识和价值创造,实现一定程度的资源和知识共享,是维持系统良性运转的有效路径.     

单自由度体系频率分析的教学探究

各质点惯性力不共线的单自由度体系的频率分析,是结构动力学教学中的一个难点。文章利用理论力学中的知识,将单自由度质点系平动时的频率计算公式ω=1/（mδ）推广到了单自由度质点系转动时的的频率计算问题,并给出了相应的转动柔度系数的确定方法。这样的处理也启发了学生将各门课程的知识进行融会贯通。     

The influence of moment of inertia on baseball/softball bat swing speed

The speed at which a player can swing a bat is central to the games of baseball and softball, determining, to a large extent, the hit speed of the ball. Experimental and analytical studies of bat swing speed were conducted with particular emphasis on the influence of bat moment of inertia on swing speed. Two distinct sets of experiments measured the swing speed of colege baseball and fast-pitch softball players using weighted rods and modified bats. The swing targets included flexible targets, balls on a tee and machine pitched balls. Internal mass alterations provided a range of inertial properties. The average measured speeds, from 22 to 31 m s⁻¹, are consistent with previous studies. Bat speed approximately correlates with the moment of inertia of the bat about a vertical axis of rotation through the batter's body, the speed generally decreasing as this moment of inertia increases. The analytical model assumes pure rotation of the batter/bat system about a vertical axis through the batter's body. Aerodynamic drag of the batter's arms and the bat is included in the model. The independent variable is bat moment of inertia about the rotation axis. There is reasonable agreement between the model and the measured speeds. Detailed differences between the two suggest the importance of additional degrees of freedom in determining swing speed.