Using thermodynamic availability to determine the energy of explosion

Current methods to determine the thermodynamic energy of explosion are based on the Helmholtz free energy. The Helmholtz free energy represents the maximum work available from a system during a constant temperature process. For many real explosions, the material is initially at a temperature or pressure higher than the ambient environment. Thus, the Helmholtz free energy does not account for all of the energy sources. The thermodynamic availability provides a general approach to determine the maximum work available from any process. Furthermore, the availability provides a much more formal and structured method for performing the calculations. This paper provides the formal basis, demonstrates the application of availabilty using a number of examples, and provides a table of availability data.     

石墨炉原子吸收法测定食品中铅

石墨炉原子吸收法测定食品中铅     

瓦斯综合防治任重而道远

平煤集团公司现有12对生产矿井。其中高突和高瓦斯矿井7对,占总个数60%,产量占一半以上。主开采煤层的丁、戊、己三组煤层,煤层最高瓦斯含量为8.81~19.4立方米/吨。平煤人深刻认识到:瓦斯不治矿无宁日。为此,平煤集团从抓好安全生产是落实“三个代表”和对党和国家、对人民负责的高度出发,结合矿井实际,下大力气,依靠科技,加大投入,改善装备,从严管理,痛下决心治理瓦斯,走出了一条在单一煤层开采、低透气性和难抽煤层条件下综合治理瓦斯的路子。2000~2002年,百万吨死亡率下降到0.352以下,为职工创造了安全生产环境,矿井生产步入了良性发展轨…     

美国拟对我玩具无线电装置发起“337调查”

近日,美国地平线业余爱好公司向美国国际贸易委员会（以下简称“ITC”）提起申请,指控中国Koko TechnologyLtd和Cyclone Technology Industrial2家企业生产以及对美销售的玩具无线电遥控发射器和接收器侵犯了其在美注册有效的专利、版权和商标权利,要求ITC对被申请人启动337调查,发布有限排除令和禁制令。所涉及专利号为7391320,版权号为TX7-226—001,商标号为3080770。     

Cooperative strategies for the availability service of repairable aircraft components

This paper specifies cooperative strategies for the availability service of repairable aircraft components and finds out which factors contribute to the emergence of a particular cooperative strategy. The strategies ad hoc cooperation, cooperative pooling and commercial pooling were specified and compared to the alternative of acting alone, i.e. solo strategy. A simulation model based on fair assumptions of the cost structure was constructed and the cooperative strategies were tested in a game theoretic setting both from the viewpoint of total efficiency and from the perspective of each participant. Despite the explicit focus on aircraft components, the findings should be relevant to any industry using a closed-loop maintenance process with repairable spare parts.     

Vent heights for emergency releases of heavy gases

A method to estimate vent heights for emergency releases of heavy gases to prevent flammability at exposed locations has been developed.     

Analysis of vent area estimation methods for non-nomograph gases

The approach discussed in this paper is an attempt to allow a broader application of a loss prevention technique and to insure efficacy of the technique.     

An instrument to determine the technological literacy levels of upper secondary school students

In this article, an instrument for assessing upper secondary school students’ levels of technological literacy is presented. The items making up the instrument emerged from a previous study that employed a phenomenographic research approach to explore students’ conceptions of technology in terms of their understanding of the nature of technology and their interaction with technological artefacts. The instrument was validated through administration to 1,245 students on completion of their 12 years of formal schooling. A factor analysis was conducted on the data and Cronbach alpha reliability co-efficients determined. The results show that a five-dimension factor structure (namely, artefact, process, direction/instruction, tinkering, and engagement) strongly supported the dimensions as developed during the original phenomenographic study. The Cronbach alpha reliability co-efficient of each dimension was satisfactory. Based on these findings, the instrument has been shown to be valid and reliable and can be used with confidence.     

电玩具检测标准中的低功率电路确定方法研究

1、范围本方法适用于非正常工作测试中判定电路是否为低功率电路;2、依据标准家用电器安规标准IEC60335-1 GB19865EN621153、定义低功率电路:按图5-1所示,器具以额定电压供电,并且将一个已调到其最大电阻值的可变电阻器连接在被调查点和电源的异性极之间,然后减小电阻值,直到该电阻器消耗的功率达到最大值,在第5S终了时,供给该电阻器的最大功率不超过15W的最靠近电源的那     

美国能源信息署(EIA)能源统计信息系统介绍

能源信息署(Energy Information Administration,EIA)是隶属于美国能源部的统计机构,成立于1977年.EIA的使命是:提供高质量的、独立于政策的能源信息,满足政府、业界和公众对能源信息的需求,促进政策的完善、市场运行效率的提高以及公众的理解,促进能源、经济与环境的协调发展.EIA依照美国相关法律,全面收集、分析并发布能源信息,特别是能源统计信息,内容涵盖能源储量、生产、需求、价格、相关财务资料和能源技术等方面.EIA高效运转的能源信息统计系统,已成为美国能源预测预警系统的重要组成部分.     

用840D数控系统解决进给轴急返安全位的方法

介绍使用SIEMENS 840D数控系统所提供的功能块来解决进给轴紧急返回到安全位置问题的两种方案。     

可资借鉴的日本能率协会

提高企业竞争力的原动力是提高生产率。而日本能率协会(JapaneseManagementAssosiation简称JMA)的主要功能就是推动企业提高生产率。日本一贯重视生产率的提高。日本提高工业生产率的一套方法,是从美国引进的。由于日本当局对此高度重视,加上工业界和学术界的认真研究,消化吸收     

美国能源独立的构想与努力及其启示

研究了上世纪70年代以来美国能源政策演变的3个阶段。从美国能源独立政策的构想与能源独立的实际路径的分析和对比中评价美国的能源政策,揭示美国迈向能源独立的真正推动力。指出：1）美国能源独立构想的实质是通过节能和发展替代能源减少石油的对外依赖;2）美国的社会节能效果不理想,但经济结构的重大调整对节能的贡献较大;3）替代能源相关政策并不仅仅是出于能源安全的考虑,而是着眼于美国的整体经济利益。美国减少石油对外依赖的突破口是以页岩气为代表的非常规油气的大发展。美国页岩气革命的成功,既有政府在资金和技术研发上的支持,也有多方面因素的综合推动。中国能源战略和政策的制定可借鉴美国在技术创新、企业家精神和宏观经济与产业体制方面的经验。     

Using column generation to solve extensions to the Markowitz model

Abstract

We introduce a solution scheme for portfolio optimization problems with cardinality constraints. Typical portfolio optimization problems are extensions of the classical Markowitz mean–variance portfolio optimization model. We solve such types of problems using a method similar to column generation. In this scheme, the original problem is restricted to a subset of the assets resulting in a master convex quadratic problem. Then the dual information of the master problem is used in a subproblem to propose more assets to consider. We also consider other extensions to the Markowitz model to diversify the portfolio selection within given intervals for active weights.     

Using the Hicks formula to evaluate an estimate of the elasticity of derived demand for toll-free numbers

Duffy-Deno & Parsons D-D & P (2012) estimated the coefficient for the price elasticity of demand for toll-free numbers (TFNs) at between −0.04 and −0.05. Here, the Hicks formula for derived demand is used to check the range of likely demand elasticity for TFNs given the special characteristics of this market. This approach suggests that the demand for TFNs is likely not more elastic than estimated by D-D & P. Therefore, the premise is sound for D-D & P's discussion of the public policy implications of highly inelastic demand for TFNs. The use of industry information for all four parameters of the Hicks formula to check a derived demand elasticity is the first of its kind in the published literature.     

用先进文化推动先进生产力的发展

文化是人类独有的生存方式，是一个民族的精神记忆，是综合国力的重要体现，先进文化是民族精神的火炬，是鼓舞人民前进的号角。代表先进生产力的发展要求，必须以先进文化作支撑。没有先进文化的强力支撑，推动先进生产力发展，便会成为无源之水，无本之木。因此，大力加强先进文化建设，特别是企业文化建设，是企业实现超常规，