无背索波形钢腹板斜拉桥上部结构施工技术

随着波形钢腹板在主梁上的广泛应用,我国诞生了第一座无背索波形钢腹板斜拉桥——溱水路大桥,该桥应用了多种预应力结构体系,具有主梁自重轻、抗震性能好、预应力效率高和避免腹板开裂等优点。但同时也给施工及监控带来了一定的困难,本文结合溱水路大桥的施工情况,分别介绍了一些上部结构主要施工技术,供类似桥梁施工参考。     

空心板梁桥纠偏复位的关键设计及施工技术

以6×20m一联预应力空心板梁桥纠偏复位工程为背景,结合现场空心板梁自身结构特点及梁下空间,设计了顶升、滑移千斤顶同步系统,利用三向千斤顶提供主动纠偏力,驱动顶升顶及梁体滑移,实现梁体横向纠偏复位。其中重点介绍了纠偏复位方案的关键设计要点及施工技术。工程实践表明设计合理,施工经济便捷,达到了预期的工程效果,对同类工程具有可借鉴及推广性。     

预应力张弦楼盖施工控制研究

大跨度张弦梁浇筑混凝土作为楼盖是一种较新颖的结构形式,但张弦梁楼盖的施工控制一直是施工领域的难题。本文结合河北师范大学张弦梁楼盖结构,对施工过程中的关键技术进行研究,建立了精确的分析模型,分析了张弦梁在平面外失稳,提出了施工过程中的位移控制和索力控制方法。     

Management of climatic heat stress risk in construction: A review of practices,methodologies, and future research

Climatic heat stress leads to accidents on construction sites brought about by a range of human factors emanating from heat induced illness, and fatigue leading to impaired capability, physical and mental. It is an occupational characteristic of construction work in many climates and the authors take the approach of re-engineering the whole safety management system rather than focusing on incremental improvement, which is current management practice in the construction industry. From a scientific viewpoint, climatic heat stress is determined by six key factors: (1) air temperature, (2) humidity, (3) radiant heat, and (4) wind speed indicating the environment, (5) metabolic heat generated by physical activities, and (6) “clothing effect” that moderates the heat exchange between the body and the environment. By making use of existing heat stress indices and heat stress management processes, heat stress risk on construction sites can be managed in three ways: (1) control of environmental heat stress exposure through use of an action-triggering threshold system, (2) control of continuous work time (CWT, referred by maximum allowable exposure duration) with mandatory work-rest regimens, and (3) enabling self-paced working through empowerment of employees. Existing heat stress practices and methodologies are critically reviewed and the authors propose a three-level methodology for an action-triggering, localized, simplified threshold system to facilitate effective decisions by frontline supervisors. The authors point out the need for “regional based” heat stress management practices that reflect unique climatic conditions, working practices and acclimatization propensity by local workers indifferent geographic regions. The authors set out the case for regional, rather than international, standards that account for this uniqueness and which are derived from site-based rather than laboratory-based research.     

新型绿色无机聚合物道面混凝土性能与应用研究

采用矿渣＋Na2SiO3和NaOH复合激发剂,制备了坍落度在160mm以上,4h抗折强度在2．5MPa以上的快硬早强自密实IPC,并进行了不同激发剂类型、矿渣掺量及养护温度等对IPC强度的影响规律试验研究,并通过机场道面现场试验,研究了IPC的施工工艺和技术。结果表明,通过严格控制原材料质量,采用合适的工艺技术,可有效保证施工质量,利用IPC快速修复的道面4h抗折强度可达3．03MPa,抗压强度达到26．19MPa,且表面性能优异,满足机场道面抢修要求。     

加强企业质量管理体系建设

对企业对质量管理体系认证的认识以及质量管理体系建设中应融通的5个关系作了深刻的阐述,并对质量管理体系的认证、运行以及在发展中与时俱进,坚持改革创新等诸方面进行了研究。本文对新时期国家转变经济发展方式的变革中,企业如何构建质量管理体系具有一定的指导作用。     

Wood pellet production costs under Austrian and in comparison to Swedish framework conditions

Owing to the rapidly increasing importance of pellets as high-quality biomass fuel in Austria and Europe within the last years, many companies, mainly from the wood industry, are thinking of entering this market. The calculation of the production costs before starting a pellet plant is essential for an economic operation. Based on comprehensive investigations within the EU-ALTENER project “An Integrated European Market for Densified Biomass Fuels” calculations of the pellet production costs loco factory for different framework conditions with basic data based on already realised plants as well as a questionnaire survey of pellet producers in Austria, South Tyrol and Sweden have been performed.

The production costs for wood pellets are mainly influenced by the raw material costs and, in the case of using wet raw materials, by the drying costs. Depending on the framework conditions these two parameters can contribute up to one-third of the total pellet production costs. Other important parameters influencing the pellet production costs are the plant utilisation (number of shifts per week) as well as the availability of the plant. For an economic production of wood pellets at least three shifts per day at 5 days per week are necessary. An optimum would be an operation at 7 days per week. A low plant availability also leads to greatly increased pellet production costs. A plant availability of 85–90% should therefore be achieved.

The calculations show that a wood pellet production is possible both in small-scale (production rates of some hundred tonnes per year) as well as in large-scale plants (some ten thousand tonnes per year). However, especially for small-scale units it is very important to take care of the specific framework conditions of the producer, because the risk of a non-economic pellet production is considerably higher than for large-scale systems.

The direct comparison of typical pellet production costs in Austria and Sweden showed the Swedish pellet production costs to be considerably lower due to larger plant capacities, the combination of pellet production and biomass CHP or biomass district heating plants and the implementation of technologies which allow an efficient heat recovery from the dryers. Moreover, another difference between the Austrian and the Swedish framework conditions is the price of electricity, which is much lower in Sweden.     

大峡水电站接地系统的特点、施工及测试

介绍大峡水电站接地系统施工过程中充分利用自然接地体的经验，并对接地系统进行计算分析、实测验证，满足了接地标准及规范验收要求。     

关于石油工业国有化与私有化的思考

本文通过对主要石油产消国的企业产权制度进行对比分析,探索面对国际油价持续上涨时所采取的国有化或私有化的战略性调整策略,寻找不同产权制度安排下经营石油资源资产与降低交易成本的一般规律,导出在租值消散博弈中原油供需均衡曲线向右上倾斜的必然结果,并初步得出不同石油资源禀赋国家参与国际石油市场分工的策略与中国应对租值消散博弈的策略。     

加强《程控交换原理》课程教学改革促进专业建设

通信工程专业是我校新开专业,几年来,根据专业建设的需要,我们对其专业基础课“程控交换原理”从教学内容、教学方法和实践教学等多个方面进行了改革与实践,取得了较为显著的成效,并对今后课程的发展提出了建设性的意见和设想。