Bicycling crash characteristics: An in-depth crash investigation study

The aim of this study was to describe the crash characteristics and patient outcomes of a sample of patients admitted to hospital following bicycle crashes. Injured cyclists were recruited from the two major trauma services for the state of Victoria, Australia. Enrolled cyclists completed a structured interview, and injury details and patient outcomes were extracted from the Victorian State Trauma Registry (VSTR) and the Victorian Orthopaedic Trauma Outcomes Registry (VOTOR). 186 cyclists consented to participate in the study. Crashes commonly occurred during daylight hours and in clear weather conditions. Two-thirds of crashes occurred on-road (69%) and were a combination of single cyclist-only events (56%) and multi-vehicle crashes (44%). Of the multi-vehicle crashes, a motor vehicle was the most common impact partner (72%) and distinct pre-crash directional interactions were observed between the cyclist and motor vehicle. Nearly a quarter of on-road crashes occurred when the cyclist was in a marked bicycle lane. Of the 31% of crashes that were not on-road, 28 (15%) occurred on bicycle paths and 29 (16%) occurred in other locations. Crashes on bicycle paths commonly occurred on shared bicycle and pedestrian paths (83%) and did not involve another person or vehicle. Other crash locations included mountain bike trails (39%), BMX parks (21%) and footpaths (18%). While differences in impact partners and crash characteristics were observed between crashes occurring on-road, on bicycle paths and in other locations, injury patterns and severity were similar. Most cyclists had returned to work at 6 months post-injury, however only a third of participants reported a complete functional recovery. Further research is required to develop targeted countermeasures to address the risk factors identified in this study.     

预应力轴心受拉钢构件高温性能试验及理论研究

进行了3根预应力轴心受拉钢构件高温试验研究。试验结果表明，高温下预应力轴心受拉构件中内置拉索和钢管所承受荷载比例随温度的变化而不断变化。升温初期拉索张力随温度升高不断增大，预应力轴心受拉钢构件轴向位移平稳发展，在达到峰值后，拉索张力随升温时间的延长而不断降低。在临界状态下，轴向位移增长很快， 预应力受拉构件中拉索均被拉断，外部钢管发生不同程度的颈缩现象。在试验结果的基础上，建立了预应力轴心受拉钢构件的有限元分析模型，得到了高温作用下预应力轴心拉杆中拉索张力和预应力钢杆轴向位移的时程全曲线。参数分析的结果表明：在其他条件相同时，预应力轴心受拉钢构件失效时的临界温度随着荷载比的增加而降低；当预应力比小于08时，预应力比对预应力轴心受拉钢构件失效时的临界温度的影响较小，当预应力比等于08时，预应力轴心受拉钢构件失效时的临界温度显著的提高；在其他条件相同时，预应力轴心受拉钢构件失效的临界温度随约束刚度比的增大而增大。最后对高温下预应力轴心受拉钢构件进行了理论分析，推导出预应力轴心受拉钢构件高温下差分计算方法，并以此为基础编写程序。通过计算结果与试验结果的对比，证明了差分计算方法的正确性。     

气相色谱法测定合成气制烯烃水相产物中低碳醇、醛、酮、酸化合物

采用气相色谱法建立了合成气制烯烃(SGTO)水相产物中低碳醇、醛、酮、酸的测定方法,对分离条件进行优化,使用标准试样测定了线性范围和工作曲线,考察了方法的精密度和准确度,并采用该方法对SGTO实际水相产物中低碳醇、醛、酮、酸进行了测定。实验结果表明,在一定质量浓度范围内,低碳醇、醛、酮、酸各组分均呈现良好的线性关系,相关系数大于0.99。标样的回收率在93.4%~109.8%之间,6次重复测定的相对标准偏差小于3.9%。SGTO实际水相产物中低碳(C1~6)醇、醛、酮、酸的分析结果表明,SGTO实际水相产物中低碳(C1~6)醇、醛、酮、酸的总含量(w)在1.5%~3.0%之间;其中,乙醇的含量最高,丙酮其次。     

A new method to assess the power performance during a lifting task in young adults

This study designs and verifies a new test for evaluating performance during a lifting task. 32 young men performed deadlift to high pull with increasing weights, and deadlift and upright row with a previously established weight of 70% 6RM, either using a Smith machine or free weights. Peak and mean power were significantly higher during deadlift to high pull with free weights than on the Smith machine, however only at ⩾50 kg. Their maximal values were achieved at about 80% and 70% 1RM. The deadlift to high pull with free weights is a reliable test with ICC > 0.80 and SEM < 10% for mean power. It is also a sensitive test for distinguishing lifting performance among healthy young individuals. It may be applied in functional performance testing of college graduate students and office workers with a prevalently sedentary lifestyle as well as construction workers with job demands based on lifting tasks.     

Numerical investigation on fracturing behaviors of deep-buried opening under dynamic disturbance

Dynamic disturbance is sometimes a non-ignorable factor to induce rock failure in underground excavation, especially for high initial geo-stressed locations. In this study, a mathematical physics model was used to characterize the failure mode of brittle rock under static geo-stress and dynamic loading. An implicit to explicit sequential solution method (IESSM) was performed to examine the dynamic fracturing behavior of an underground opening due to dynamic disturbance. In the numerical simulation, the characteristics of strain energy density (SED) and fracturing zone were investigated under various lateral pressure coefficients. The results indicated that different failures were induced around the opening subjected to dynamic. With lower lateral pressure coefficient, spalling is induced at roof and spandrel with a long period for releasing strain energy. With the increase of the lateral pressure coefficient, violent strain rockbursting is observed in highly stressed locations, with instantaneous release of massive strain energy. Moreover, when the geo-stress of lateral pressure coefficient is high enough, the occurrence location and fracturing zone of rockbursting will not be greatly influenced by the dynamic disturbance, including its amplitude and action direction.     

高层建筑火灾致因因素分析与防火安全对策

随着城市化脚步的快速发展，城市高层建筑越来越多，高层建筑带来的安全隐患也时刻威胁着人们生命财产安全。本文针对高层建筑火灾的发生因素以及防火安全对策进行了分析，希望为相关部门在对高层建筑的救火、防火方面提供帮助。     

原料中的NH_3含量对甲醇制丙烯催化剂性能的影响

在连续流动固定床微型反应器中,对甲醇制丙烯的ZSM-5分子筛催化剂的性能进行了评价,并采用XRD、吡啶吸附-FTIR和TG等方法对反应后的催化剂进行了表征,考察了原料中的NH3含量对催化剂性能的影响,同时考察了NH3含量与催化剂寿命和甲醇转化率的关系。实验结果表明,在催化剂装填量10 g、常压、480℃、甲醇重时空速1.0 h-1、水与甲醇的质量比0.69的反应条件下,NH3的存在对ZSM-5分子筛催化剂的晶型结构没有影响,但对酸性影响较大;随NH3含量的增加,尤其是当NH3含量大于0.010%(w)时,催化剂的积碳量显著降低,催化剂的寿命大幅缩短。     

A fast and efficient load flow technique for unbalanced distribution system

This paper presents a fast and efficient load flow technique for unbalanced distribution system. The proposed load flow technique is derived by promulgating the concept of conventional backward forward sweep (BFS) technique of power flow study for distribution system. The proposed technique employs a novel load-impedance matrix (LIM) to calculate the bus voltages in a single step unlike the conventional BFS approach which involves two separate steps (backward sweep and forward sweep) to perform the same and this improvement is claimed as the novelty of this work. This distinctive feature makes the proposed algorithm faster in operation. Nodal voltages, at any iteration, may be calculated, directly, from the values obtained in the previous iteration by utilizing LIM. A simple concept of set theory is adopted here to construct the LIM. Special treatments are also included in this method to analyze weakly meshed systems. The proposed technique is flexible enough to accommodate any sort of changes in the existing network topology through LIM. It is tested on different three-phase balanced and unbalanced radial distribution systems as well as weakly meshed networks for load flow study. A separate case study is also presented to check the validity of the proposed load flow technique for various transformer connections. The obtained results demonstrate the effectiveness of the proposed technique. Furthermore, performance comparison reveals that the proposed algorithm is, computationally, faster and robust than the conventional power flow techniques reported in the recent state-of-the-art literatures.     

电缆隧道内阻燃试验研究及应用

分析电缆隧道火灾危险性及成因,结合电缆隧道火灾特点,模拟电缆隧道火灾进行了电缆阻燃及灭火试验,通过试验现象和数据分析,比较了各类电缆阻燃及灭火设施的阻燃灭火性能,总结了电缆隧道的阻燃、灭火、防火分隔、疏散等设施的设置原则,为电缆隧道消防工程设计、施工及验收提供最真实的试验数据支持。     

浅谈如何实现项目二次创效

工程项目二次创效,是指在保证满足工程质量、工期等合同约定的前提下,通过加强对工程项目施工过程有组织、有系统的进行预测、计划、控制、核算、分析、考核等科学管理活动,以达到强化经营管理、降低工程成本、实现目标利润、创造良好经济效益之目的。