Effects of repeated exposures to severely cold environments on thermal responses of humans

Abstract

This study was conducted to investigate the effects of different exposure rates on thermal responses with the total cold exposure time the same under each of the conditions. After resting in a warm room (25°C) for 10 minutes, six male students wearing standard cold protective clothing entered an adjoining cold room (— 25°C). Each 5-, 10- and 20-minute cold exposure was repeated 12, 6 and 3 times, respectively. Each cold exposure was followed by a similar duration of rest at 25°C. Total cold exposure time was the same under the three conditions. Rectal temperature, skin temperatures, blood pressure, 17-hydroxycoyticoids (OHCS), counting task and subjective responses were measured. At the end of the cold exposure skin temperatures in the shorter exposures were higher than those in the other conditions, except on the foot. Discomfort due to cold was less in the shorter exposures and manifestation of discomfort was delayed. However, there were no differences among the three conditions in the fall of rectal temperature and urinary excretion of 17-OHCS, which are good indices of cold stress, Moreover, increase in blood pressure and decrease in counting task due to cold were not different among the three conditions. Even though the cold exposure time for each stay was short, when cold exposures were repeated frequently, cold stress of the whole body and decrease in manual task performance were the same as in the longer cold exposure.     

体重指数BMI与两种富裕性疾病患病率的关系

本文基于上海延吉社区1.7万多人的调查结果,从统计的角度出发,分性别、年龄讨论了BMI与两种富裕性疾病患病率之间的关系。     

在手机辐射作用下人体内外的场强分布

利用FDTD法在建立人体电磁模型的基础上，计算了在手机辐射作用下，人体内外的场强分布。在计算过程中，采用了硬吸收边界条件来解决FDTD算法中计算区域的截断误差问题，即把吸收性能良好的吸波材料加到计算空间的边界上以吸收边界上的入射波，消除反射波。计算结果表明，手机的辐射绝大部分被人体的皮肤所吸收，人体内部在手机辐射作用下的场很弱。因此，在非长期地、连续性地使用手机的情况下，手机的辐射应不会对人体的健康产生较大的影响。     

-377 m硐室振动给料机本体失效分析与对策

通过非均匀受载造成振动给料机本体变形、开裂的分析，提出并实施了焊接加强筋，改变电机位置，调整有关部件间隙等措施，使故障率降低，实现矿山稳定生产。     

基于本体的车身设计知识库的构建方法研究

在研究本体、知识库相关理论,分析车身设计领域知识形态结构的基础上,建立了车身设计知识本体,并将本体论引入到车身设计知识的管理系统中,提出了构建基于本体的可重构的车身设计知识库,并在理论上提出了该系统的框架结构。     

基于本体的车身设计知识库的构建方法研究

在研究本体、知识库相关理论,分析车身设计领域知识形态结构的基础上,建立了车身设计知识本体,并将本体论引入到车身设计知识的管理系统中,提出了构建基于本体的可重构的车身设计知识库,并在理论上提出了该系统的框架结构.     

建构 现实性的戏剧与建筑戏剧的真相

文章讨论了建构与技术、与人的身体的关系,揭示了现代主义以来建构概念所面临的威胁。通过对建构概念历史发展的回顾,作者指出建构概念本身亦应随时代变化而加以充实,现代主义对自由的追求在本质上与古老的建构概念并不矛盾,建构所展现的真实是一种表象,是对真实的诠释,是转译而非简单的赤裸裸的直陈。     

Transmission Power Control for IEEE 802.15.6 Body Area Networks

Energy consumption is an important issue in body area networks (BANs). In this letter, we propose an energy efficient transmission power control scheme for IEEE 802.15.6 BANs, which can improve energy efficiency by adaptively adjusting the transmit power in an on‐demand way to adapt to varying channel environments. Simulations are performed to evaluate the performance, and it is shown that the proposed power control scheme outperforms traditional ones in terms of energy efficiency without significant reliability degradation.     

凸轮机构的活动定位在机体双面铣中的应用

凸轮机构具有升程准确、自锁性能好、操作简便等优点，把凸轮机构的活动定位应用于机体双面铣的夹具中，迭到了定位准确，操作简便可靠，经济实用的目的。     

半挂式废钢运输车设计

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