地形起伏地区管道水联运充水排气过程分析

针对油气长输管道投产前通常会进行充水清管、调试和吹扫(常规称:水联运),由于埋地管道随地形起伏经过无数个相对高点和低点,管道充水前处于自然状态,一旦管内充水,就会将管内空气归聚成封闭空间,形成多个带压气团随水头移动,时而被压缩,时而被膨胀,从而造成管道断流,影响泵站正常工作,严重的还会导致管道泄压装置受损、爆管事故等问题,分析了管道水联运过程中不同地形起伏高点和低点带压气团的成因和状态,用实例计算了带压气团对管道水联运的影响及排除方法,从而为长输管道投产前正常的水联运作业提供借鉴。     

Gap acceptance behavior at unsignalized intersections: Effects of using a phone and a music player while driving

Objectives: The present study is an attempt to analyze and compare the distraction effects caused by the use of a phone and a music player at unsignalized intersections.

Method: Eighty-eight participants performed simulated driving experiments where they faced a sequence of gaps in the major road traffic at 2 unsignalized intersections. In this process, their driving behavior was evaluated in terms of gap acceptance probability, accepted lag, and maneuver completion time. These parameters were modeled with a generalized estimating equation (GEE) method by considering distraction, demographic factors, driving history, maneuver types, and driving attributes in the approach and completion zones as independent variables.

Results: The results showed that gap acceptance probability decreased by 46% during the conversation task, whereas it increased by 66% during the music player task. Lower gap acceptance could be a compensatory behavior adopted by drivers during the conversation task, whereas no such measure was adapted during the music player task. The results indicate that a higher approach speed during the music player task might have led to increased gap acceptance. Further, though the effect of distraction on the accepted lag was not evident, the completion time was reduced during the conversation task.

Conclusions: Overall, the results suggest that drivers are more likely to adopt a compensatory measure in complex driving situations only if they perceive a high risk. Hence, drivers are exposed to a greater risk while operating a music player, because this is not perceived as risky behavior.     

基于地表沉陷控制的膏体充填材料的性能优化研究

充填材料性能是充填开采控制地表沉陷的一个重要因素,为克服传统充填材料性能优化试验耗时长、成本高、人为误差较大的缺点,探索将传统正交试验与模糊决策相结合进行充填材料性能优化。基于L9(33)正交试验,确定了S1~S55组充填材料性能优选方案。在综合分析充填材料性能影响因素的基础上,建立充填材料性能优化指标体系,构建AHP-FUZZY模糊综合优选模型对方案进行比选,并分析了正交试验中各因素水平变化对最优方案的敏感性。结果表明:膏体充填材料性能最优方案为“S4”即水泥含量15%,灰矸比1∶2,质量浓度75%,决策结果与试验结果相符,且“灰矸比”对充填材料性能优化的敏感性程度最高,在实际膏体充填开采中要严格控制粉煤灰和煤矸石掺量。     

早强充填体与矿柱相互作用的声发射特征试验研究

为了更好厘清充填体与矿柱相互作用机理,提出使用石蜡作为胶结剂,通过尾砂加石蜡拌合模拟充填体,建立充填体与矿柱相互作用的复合体模型。基于充填体与矿柱侧边存在临空面这一实际情况,采用自制的双轴加载装置模拟井下早强充填体与矿柱共同受载情况。借助声发射仪监测充填体与矿柱在加载作用下的AE振铃计数及AE点发生位置。试验结果表明:尾砂+石蜡模拟充填体加载破坏后存在残余应力;充填体与矿柱复合体试样在加载过程中的内部破坏主要发生在充填体内和充填体与矿柱接触带区域。     

TREND ASSESSMENT OF WATER QUALITY TIME SERIES1

ABSTRACT A general methodology is described for identifying and statistically modeling trends which may be contained in a water quality time series. A range of useful exploratory data analysis tools are suggested for discovering important patterns and statistical characteristics of the data such as trends caused by external interventions. To estimate the entries in an evenly spaced time series when data are available at irregular time intervals, a new procedure based upon seasonal adjustment is described. Intervention analysis is employed at the confirmatory data analysis stage to rigorously model changes in the mean levels of a series which are identified using exploratory data analysis techniques. Furthermore, intervention analysis can be utilized for estimating missing observations when they are not too numerous. The effects of cutting down a forest upon various water quality variables and also the consequences of acid rain upon the alkalinity in a stream provide illustrative applications which demonstrate the effectiveness of the methodology.     

建筑物下采煤技术的研究现状与发展趋势

我国建筑物下采煤的研究从20世纪60年代开始,先后在本溪、鹤壁、抚顺、枣庄、峰峰、蛟河等矿区进行试验,取得了成功的经验和宝贵的监测资料。在综合分析大量文献的基础上,从协调开采法、充填开采方法、条带开采、覆岩离层注浆等多种开采技术对建筑物下开采方法进行了研究和论述;展望了我国建筑物下开采的发展趋势,认为覆岩离层注浆、矸石充填、条带开采、原地重建抗变形房将是我国建筑物下采煤技术的发展方向。     

液化石油气充装作业危险性分析及对策

分析了液化石油气充装过程中存在的危险、危害因素及产生的原因,提出了有针对性的安全防范措施。     

囊袋结构消防服内衬的力学特性研究

为保护消防员不受火场坠落物造成的伤害,设计制造1种具有缓冲功能的弹性囊袋结构内衬.基于万能材料试验机拉伸试验确定囊袋结构材料A剂与B剂的最佳比例为1:1;根据理想气体状态方程和弹簧模型推导得到囊袋内填充气压的最佳数值;以此为依据对囊袋结构内衬进行不同加载速率的压缩试验,得到应力应变曲线.研究表明:囊袋结构压缩曲线分为应...     

滤料级配过滤含聚污水数值模拟研究

以磁铁矿滤料与石英砂滤料为填设滤料层的级配模式一直广泛应用于油田含聚污水处理过程中,但这种滤料级配与污水过滤性能之间的影响关系及规律认识却较为缺乏,本文以悬浮粒子吸附与截留形成的聚集特征为切入,定量分析出水水质特性,对含聚污水过滤过程中滤料级配的影响效果展开数值模拟研究。研究认为：磁铁矿滤料层厚度较大的级配模式过滤具有更好的悬浮粒子吸附与截留效果,对更小粒径悬浮粒子过滤能力更优,但滤料填充高度比与过滤效果存在一定适配性;以1.28以上磁铁矿滤料厚度较大的级配模式过滤较低含聚浓度污水、以1.67以上磁铁矿滤料厚度较小的级配模式过滤较高含聚浓度污水,均可以使出水悬浮固体颗粒与油滴含量均低于5mg/L,满足过滤出水水质指标要求。     

Soil drying in a tropical forest: Three distinct environments controlled by gap size

Soil water and temperature regimes in the tropical moist forest on Barro Colorado Island, Panama, were simulated directly from meteorological data using the model SWEAT. Separate field observations from root-exclusion, litter-removal and control treatments in one small and one large forest gap were used for calibration and validation. After irrigating all treatments to field capacity, soil matric potential and temperature were measured over 17 days at four depths ≤50 mm using the filter-paper technique and bead thermistors. Understorey environments were also simulated under the same initial conditions. The results suggest that three distinct scenarios, controlled by gap size, describe how the above- and below-ground processes controlling soil drying are coupled: (1) in the large gap, root water extraction by surrounding trees is negligible so soil drying is dominated by evaporation from the soil surface. Soil temperature is dominated by direct solar heating and cooling due to evaporation. (2) In the small gap, root water extraction dominates soil drying with soil evaporation playing a minor role. Soil temperature is still dominated by direct sunlight with some cooling due to evaporation. (3) In the understorey, root water extraction dominates soil drying. Soil temperature is dominated by heat conduction from deep soil layers with some evaporation and sensible heat transfer. The contrasting soil drying regimes imposed by variation in canopy structure enhance micro-environmental heterogeneity and the scope for differential germination and seedling establishment in coexisting tropical tree species.