Understanding storage environmental stability during power outages: A key issue in sub-tropical climates

Efficient air-conditioning systems facilitate climate control in modern museums, libraries, and archives. The climate in Hong Kong is typically hot and humid, so the survival of collections is highly dependent on 24-hour air-conditioning systems to maintain the desired environment in repositories of archives and books, or artefact stores. The continuous operation of such systems in turn relies on a number of factors, such as uninterrupted electricity supply, an active maintenance programme, daily monitoring of their performance and quick response to irregularities as well as backup or alternative systems to support the air-conditioning load in case they are down for servicing. From the risk management point of view, unlike the latter four factors, electricity supply is an external factor that cannot be guaranteed. Fluctuation in the power level that results in stoppage of air-conditioning equipment is not uncommon even in well-developed countries. Long power outages could be catastrophic as they might lead to irreversible damage to collection items as a result of fast, large, changes in temperature and relative humidity (RH) towards the external environment if the air-tightness or hygrothermal stability of the storage are not good enough. Understanding storage environmental stability, especially during electrical power disruptions, is an essential part of the preservation measures and disaster preparedness necessary to protect valuable collections in cultural heritage institutions in the region.     

高校青年体育教师流动问题的社会学研究

综合运用文献资料、调查访问、逻辑分析等研究方法,对高校青年体育教师的流失问题进行社会学分析。结果表明：青年教师的流动在高校中普遍存在,流失的虽是少部分,但隐形流失是存在的不可忽视的问题。流动的对象、方向不合理,后果严重。思想不稳定及缺乏敬业精神等是流失的主观原因,工资待遇低、不被重视、环境艰苦等是流失的客观原因,并对青年体育教师的稳定提出建议与对策。     

四川电大教育网教务管理系统及其安全机制

随着四川电大教育事业的发展与教学方式的多元化，特别是远程教育的不断发展，为加强全省电大系统教务管理的规范性与高效性，建立一个完善的、相互衔接和易于升级的教务管理系统是十分必要的。它能正确有效地管理四川电大的学生学籍、成绩 和毕业等多方面的信息，并且系统地采取了一定的安全措施，对有效数据进行保护，使得信息更具有 可靠性。     

Critical physics agency: further unraveling the intersections of subject matter knowledge, learning, and taking action

In this rejoinder to Bryan Brown and John Reveles, we highlight the facts that (a) sociocultural theories of learning do not go far enough because they fail to address a number of issues and (b) we require concepts such as power and positionality to understand science learning.

Construction for neutrino experiment starts at Daya Bay

The ground-breaking ceremony for the Daya Reactor Neutrino Experiment,China's largest single project of international collaboration in basic science as well as the biggest one between US and China,was held at Daya Bay Nuclear Power Base in Shenzhen on 13 October,2007. Chaired by CHEN Hesheng, director of the CAS Institute of High Energy Physics(IHEP),the ceremony was attended by high-     

西电东送输入区环境效应综合评价

西电东送是解决我国能源空间产销不平衡的重要途径,也是改善东西部地区环境质量的重要手段之一.对东部输入区而言,西电是清洁能源,其环境效应显著.具体体现在西电输入可以直接替代东部地区原有小火电,减少污染物的直接排放,尤其是消除对环境造成极大破坏的SO2排放导致的酸雨污染;同时将间接推动东部地区能源消费结构的优化,为东部地区经济发展提供更多的环境支撑.本文以广东为例,利用计量经济学方法定量分析西电对输入区的环境效应及其潜在的间接环境效应.数量分析结果表明,西电的输入对降低东部地区与电力相关的污染物排放作用是显著的.针对西电输入、输出区环境容量不同的经济价值,提出西电东送可以同时提高双方的环境容量及其边际价值,提高双方的总体社会福利水平.以西电东送为纽带,推动区域经济合作和协调发展,实现西电东送战略的持续实施.     

无线传感器网络研究

无线传感器网络集成了传感器、微机电系统和网络三大技术而形成的传感器网络是一种全新的信息获取和处理技术,已经成为当今的热门研究领域之一,在国防安全、工农业领域各种控制、城市管理、生物医疗、环境监测、抢险救灾、防恐反恐、危险区域远程控制等许多领域都有重要的科研价值和实用价值,具有十分广阔的应用前景。本文讨论了无线传感器网络的基本概念和一些重要研究领域,并且介绍了无线传感器网络与IPv6的可能的一些契合点,它是无线传感器网络进行大规模就用的重要议题。     

1960-1970年代美国“红种人权力”运动与土著族裔意识的复兴

"红种人权力"运动作为美国印第安人历史上的重大事件之一,并非仅具有象征性作用,而是产生了重大影响,推动印第安人族裔意识的勃兴.这主要表现在三个方面:一是推动印第安人在1960-1970年代广泛开展泛印第安人抗议运动;二是全国性土著组织如雨后春笋般纷纷建立;三是激发了印第安人个体的族裔认同感和民族自豪感.所有这些又进一步促使土著民族自治运动以星火燎原之势在全国范围内迅速展开.     

Numerical investigation on the flow and power of small-sized multi-bladed straight Darrieus wind turbine

Straight Darrieus wind turbine has attractive characteristics such as the ability to accept wind from random direction and easy installation and maintenance. But its aerodynamic performance is very complicated,especially for the existence of dynamic stall. How to get better aerodynamic performance arouses lots of interests in the design procedure of a straight Darrieus wind turbine. In this paper,mainly the effects of number of blades and tip speed ratio are discussed. Based on the numerical investigation,an assumed asymmetric straight Darrieus wind turbine is proposed to improve the averaged power coefficient. As to the numerical method,the flow around the turbine is simulated by solving the 2D unsteady Navier-Stokes equation combined with continuous equation. The time marching method on a body-fitted coordinate system based on MAC (Marker-and-Cell) method is used. O-type grid is generated for the whole calculation domain. The characteristics of tangential and normal force are discussed related with dynamic stall of the blade. Averaged power coefficient per period of rotating is calculated to evaluate the eligibility of the turbine.     

电力工程造价的管理和控制

本针对电力工程造价问题，阐述了项目法人在电力工程建设的各个阶段，加强管理，有效控制电力工程造价的几点意见。