高空作业机械报警系统分析

<正>现代高空作业机械作业高度越来越大,结构越来越复杂,自动化程度越来越高,安全要求提到前所未有的高度。具有智能化监视和实时数据采集功能的高空作业机械报警系统,能够提示操作人员做出正确操作,减少误操作所带来的事故,已经成为衡量高空作业机械性能的一个重要方面。     

吊车梁(中级工作制)增设制动梁经济分析

根据工程实际案例,使用净现值法进行分析,得出在中级工作制情况下,吊车梁应增设制动梁的结论,同时也为业主、设计人员在决策、设计时提供重要的参考。     

绩效评价在进度控制和劳动力资源分析中的应用

在工程建设过程中,监理需要对现场的资源情况进行严格监控,这一项工作可以通过绩效考核来实现,通过绩效考核可以分析现场实际进度情况及劳动力资源的生产效率,并预测下一阶段的劳动力资源需求量。     

The effects of outdoor air supply rate on work performance during 8-h work period

The purpose of this study is to evaluate the effect of ventilation rate on work performance and perceived air quality through short-term laboratory experiments. The experiment was designed to simulate office work, and a laboratory space was modified using new finish materials to become a typical office space. High levels of volatile organic compounds (VOCs) were found in the exposure chamber, most probably originating from the new finishing materials that were present. Twenty-four subjects were divided into six groups that were randomly exposed to the three ventilation rates, 5, 10, and 20 l/s per person. The subjects performed work tasks three separate times for each ventilation rate over an 8-h exposure period. The work performance of the subjects logarithmically improved with increased ventilation rates, which was similar to the previous research findings. Statistical significance was found for addition task, text-typing task, and memorization task. Increased work performance in this experiment was slightly lower than the results of previous short-term laboratory experiments, yet remained higher than results of previous long-term field experiments. However, it was difficult to directly compare the results of this experiment with those of previous experiments, because of the higher concentration of VOC present in the office rooms and the learning effect associated with the repeated tasks. PRACTICAL IMPLICATIONS: The results of this experiment show that ventilation had positive impacts on perceived air quality and work performance for the subjects tested. Work performance logarithmically increased by approximately 2.5-5% as ventilation rates were increased from 5 to 20 l/s per person. The positive effect of ventilation rate on work performance was shown to be limited at the low ventilation rate. The positive effects on work performance were at lower ventilation rates. The learning effect in repeated work performance tasks could increase the uncertainty of the work performance analysis in 8-h exposure period.     

浅谈热泵系统的发展及研究现状

在当前能源供应趋紧、环境保护要求不断提高的形势下,人们在不断地寻求既节能又环保的新能源.热泵作为新能源的一种,能够实现把低温热能传递给高温热能的功能,能够利用自然资源和余热资源中的大量热量,有效节约民用及工业所需的一次能源使用量.对于几种热泵系统,如地源热泵系统、地表水源热泵、空气源热泵,本文主要介绍几种热泵系统的发展...     

当前标准化工作存在的问题及发展战略

[编者按]本文作者在阐述当前标准化工作存在的问题时以其所在城市的石化行业为例,事实上同样的问题存也存在于包括建材行业在内的其他各行业中,这些问题应引起相关部门的重视.     

质量管理体系之管理评审工作

分析了质量管理体系之管理评审工作的目的和意义,对评审计划、输入、输出的工作程序进行了介绍,并论述了管理评审时间、方法、记录及报告等内容,就管理评审工作提出了几点建议。     

沥青混合料配合比设计系统开发的可行性分析

针对当前沥青混合料配合比设计依赖于经验及EXCEL试算的现状,进行了基于.NET平台沥青混合料配合比设计系统的软件开发,介绍了系统设计的主要流程和用到的关键技术,表明利用沥青混合料配合比设计软件设计级配可提高设计效率和准确度,具有一定的推广价值。     

高性能混凝土及其发展动向

由于混凝土技术发展的不平衡性，世界不同国家及学者对高性能混凝土的认识也不尽一致；而高性能混凝土及大掺量粉煤灰混凝土已成为当今世界混凝土发展的两大主题，同时衍生出的绿色混凝土和水工高性能混凝土。对今后混凝土的研究与发展也将产生重要影响，本文结合水工高性能混凝土中高活性掺合料的研究对上述问题进行了阐述。     

高性能混凝土发展的回顾与思考

在本文中作者回顾了我国高性能混凝土的技术进展，同时也分析讨论了最近几年混凝土技术出现的几个新问题：裂纹、按服务年限设计混凝土的理念以及现代水泥的品质问题。作者从混凝土最早期的弹性模量及极限拉应变的急剧变化分析了早期裂纹的成因；并提出了混凝土24h抗压强度应小于10MPa以防止裂缝的建议。作者认为基于国内外的实际工程经验和教训以及耐久性研究成果，辅以服务寿命预估模型，目前我们已能按服务寿命设计混凝土。降低混凝士的水渗透系数固然能提高耐久性，但是过度追求低水渗透性，也即过高的强度对实际结构物的耐久性可能是不利的，因为易于开裂。现状水泥工艺生产的高C3S、高C3A、高早强和高比表面的水泥对混凝土的抗裂性和耐久性都有不利影响。因此，高性能混凝土应该同时具有高耐久性、不易开裂性、适当的高强度和良好的工作性．     

电气火灾监控系统的功能可靠性分析

从建筑消防设施系统分析的角度,概述了对电气火灾监控系统(Alarm and control system for electric fire prevention)在建筑设计理念上的定位、功能、电气火灾监控产品的性能要求,结合可靠性理论对独立式和非独立式电气火灾监控系统的功能可靠性进行了分析,指出了应用选型范围.     

天津农村城市化发展水平评价指标体系研究

本文以农村城市化的内涵为基础,建立天津农村城市化发展水平评价指标体系,运用模糊综合评价法对天津郊区县农村城市化发展状况进行分析评价,并提出政策建议,为天津加快农村城市化进程提供决策参考。     

某交错桁架结构体系动力性能分析

采用数值模拟分析方法,对采用交错桁架结构体系的工程实例进行多遇地震和罕遇地震下的整体受力分析,探讨其抗连续倒塌性能特点。计算结果表明:结构平面布置规则、竖向刚度均匀时,在多遇地震作用下,层间变形较小,各项指标均满足规范要求;罕遇地震作用下,结构最大层间位移角小于规范限值,可实现"大震不倒"的抗震性能要求;交错桁架结构体系的水平及竖向关键构件失稳后,结构端部桁架杆件虽然屈服,但未发生整体稳定性破坏,结构不会发生跨塌;柱发生破坏时,柱端纵梁及桁架形成转换梁效应,将上部柱传递下来的荷载进行重分配,结构不会发生连续性倒塌。     

相变材料式蓄冷系统的动态模拟及运行分析

建立了相变材料式蓄冷系统的三大部件即蓄冷设备、制冷系统、空调负荷的数学模型，对常规系统、全蓄冷系统和部分蓄冷系统分别进行了动态模拟，计算出供冷季的总运行能耗和电费，分析比较了这三种系统的特点。     

当前绩效管理工作中存在的问题与对策

从系统性、误导性、差异性和统一性方面阐述了当前绩效管理工作中存在的弊端,提出了搞好绩效管理工作的合理对策,从战略一致性、敏感性、可靠性、可接受性方面介绍了判断绩效管理系统是否有效的方法.     

防火监督工作开展的困境及策略

分析了我国防火监督工作的现状,针对防火监督队伍建设水平低、防火监督机制不健全、监督工作表面化等问题,提出了加强防火监督工作的策略,以有效降低火灾的发生率。     

建筑外墙保温系统防火性能分析与改进方法

介绍了建筑外墙保温系统的常用材料,针对建筑外墙保温系统引发火灾的原因,分析了其保温系统的防火性能,并提出了防火性能的改进方法,以最大限度的减少火灾的发生。     

矿渣粉的性能分析

本文分析了高炉矿渣从混合粉磨到分别粉磨的发展,国内外矿渣粉标准的制定和矿渣粉等量替代水泥后的工作性能,最后指出矿渣粉是一种绿色生态建材,需要进一步的开发和研究.     

浅谈绿色高性能混凝土的发展

本文重点论述发展绿色高性能混凝土的必要性,比较客观的论述研发绿色高性能混凝土的可行性.通过混凝土发展的历史,作好绿色高性能混凝土的开发.     

Ventilation and performance in office work

Outdoor air ventilation rates vary considerably between and within buildings, and may be too low in some spaces. The purpose of this study was to evaluate the potential work performance benefits of increased ventilation. We analyzed the literature relating work performance with ventilation rate and employed statistical analyses with weighting factors to combine the results of different studies. The studies included in the review assessed performance of various tasks in laboratory experiments and measured performance at work in real buildings. Almost all studies found increases in performance with higher ventilation rates. The studies indicated typically a 1-3% improvement in average performance per 10 l/s-person increase in outdoor air ventilation rate. The performance increase per unit increase in ventilation was bigger with ventilation rates below 20 l/s-person and almost negligible with ventilation rates over 45 l/s-person. The performance increase was statistically significant with increased ventilation rates up to 15 l/s-person with 95% CI and up to 17 l/s-person with 90% CI. Practical Implications We have demonstrated a quantitative relationship between work performance and ventilation within a wide range of ventilation rates. The model shows a continuous increase in performance per unit increase in ventilation rate from 6.5 l/s-person to 65 l/s-person. The increase is statistically significant up to 15 l/s-person. This relationship has a high level of uncertainty; however, use of this relationship in ventilation design and feasibility studies may be preferable to the current practice, which ignores the relationship between ventilation and productivity.