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大庆油田稠油流变特性的分析 总被引:1,自引:0,他引:1
对大庆油田稠油开展流变特性实验研究,在一定温度范围内作出其黏温曲线和流变曲线,对实验结果进行归纳分析,确定稠油的流体类型以及牛顿流与非牛顿流的转变点,总结出稠油流变规律,为实际生产提供了一种有效的理论依据。 相似文献
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针对目前不同因素作用下海水泥浆流变特征及流变方程不明的问题,选取两种典型的增黏剂开展一系列室内流变试验,探究不同增黏剂含量及环境温度对海水泥浆流变参数的影响规律,并从微观层面揭示泥浆流变参数变化机理。结果表明:相较于羧甲基纤维素钠(CMC),同等含量的增黏剂聚阴离子纤维素(PAC)具有更好的海水泥浆流动性增强效果,可显著提升泥浆黏度和物理稳定性,含0.4%PAC、12%钠基膨润土的海水泥浆的黏度有较大程度提升;不同PAC含量下海水泥浆流动模式均符合幂律模型,且随温度的升高,其稠度系数k和流变指数n分别呈下降和增加趋势;微观角度上,增黏剂分子链上的羟基与膨润土颗粒之间相互作用形成分子内氢键,是增黏剂起到增强泥浆流动性作用的主要原因。 相似文献
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浆液流型及流变参数的时变规律是建立注浆扩散理论模型的前提。为探究氧化钙和碳酸钠复合激发矿渣灌浆材料流变特性,首先采用氧化钙和碳酸钠(物质的量比为1∶1)为激发剂制备出析水率和结石体抗压强度优于42.5号普通硅酸盐水泥浆的新型灌浆材料,接下来采用旋转黏度计对不同水胶比、不同水化时间灌浆材料的流变特性进行测试,基于测试结果探讨了水胶比、水化时间对灌浆材料流型及流变参数的影响规律。结果表明,水胶比对氧化钙-碳酸钠复合激发矿渣灌浆材料流变模式有较大影响,水胶比为0.60~1.00的灌浆材料流型不是某种单一流型,分属宾汉姆流体、牛顿流体。塑性黏度和屈服应力随水胶比增大呈幂函数关系减小。与水泥基注浆材料类似,氧化钙-碳酸钠复合激发矿渣灌浆材料在注浆过程中流型保持不变,只是流变参数随水化时间发生变化。灌浆材料水胶比越大,水化时间对剪切应力与剪切速率关系、流变参数量值影响越小。与水泥基注浆材料不同的是,新型灌浆材料塑性黏度随水化时间变化规律符合幂函数而非指数函数。水胶比为0.60、0.65的浆液屈服应力随水化时间增加呈线性增大,而水化时间对水胶比为0.70、0.75的浆液屈服应力影响不显著,可认为屈服... 相似文献
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采用RV2旋转黏度计测定了石油一厂渣油在60~140℃范围的流动特性参数,当油温在90%以上时,渣油为牛顿流体,油温低于90℃时,渣油为非牛顿流体,而且油温越低非牛顿特性越强,渣油的黏温关系与原油类似,其黏温曲线可分为放射段和直线段,但非牛顿特性强于原油。 相似文献
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Ingmar Andrasson 《先进运输杂志》1998,32(1):23-34
A survey of research and development in advanced transit has been made by Chalmers University of Technology in Gothenburg in cooperation with Trans21 in Boston. Summary findings are reported for fourteen academic research programs and ten development programs for PRT. An earlier version of this paper was presented at the International Conference of PRT and other Emerging Systems held in Minneapolis in 1996. 相似文献
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AbstractDespite a concentration of container traffic in the southeast of the UK over the last few decades, regional ports are attempting new development strategies to capture or retain specific traffic segments. These include intra-European short-sea traffic and a potentially increasing feeder market. These trends are reflected in the movement of different container types, which result in a number of planning challenges related to changing infrastructural and operational requirements. This paper uses highly disaggregated data on container type movements to address three issues that can inform these planning challenges. First, the imbalance of trade resulting in empty container repositioning; second, the requirement for gauge-cleared rail routes to cater for the increasing proportion of high-cube containers; and third, the specialisation of European short-sea traffic at secondary UK ports. The results reveal the disproportionate repositioning of empty containers at Scottish ports and the importance of 45?ft, high-cube and pallet-wide containers at regional ports, highlighting their focus on intra-European short-sea traffic and raising difficulties relating to their lower quality of landside infrastructure (particularly rail) in comparison to the large south-eastern ports. The potential repercussions on hinterland infrastructure development raise questions about both public and private sector responses to regional port development. 相似文献
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管道风险分析指数评分法中重要步骤之一就是确定影响管道事故因素的权重,各个管道风险因素在整个管道事故中所占的权重是不相同的。针对目前管道风险分析指数评分法基本假设之一(各因素的分值范围都是0~100分),为了更加客观、准确、合理地反映各个风险因素对于管道事故的影响程度,提出并论述了依据层次分析法的数学逻辑性进行综合计算得出管道风险因素的权重,然后对评分法中各个因素的最高分值,根据其权重不同进行相应调整,从而增强评价者对风险因素的认识和评判能力,提高管道风险评价结果的准确性。 相似文献
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The concept of accessibility has acquired numerous meanings along multiple dimensions during the century of its evolution. This essay argues for the salience of two dimensions: application-based and definition-based. In its application, accessibility has incorporated positive and normative dimensions which have varied in prominence over time. In its definition, accessibility has varied between a mode of evaluation incorporating measured mobility and proximity, on the one hand, and a predefined market basket of urbanist improvements to transportation and land use systems, on the other. Advocates of the accessibility shift should emphasize both the measured approach to accessibility and accessibility’s normative side. 相似文献
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The big paradigm for cities nowadays is to study the movement of pedestrians at the interface between metro and bus systems – metro–bus interchanges. When these interchanges are not well designed, walking is inefficient and can be unsafe for pedestrians. This paper analyses, by means of a pedestrian microsimulation model, metro–bus interchange spaces in order to propose planning guidelines for the city of Santiago de Chile. Specific objectives are (1) to identify the variables that provide efficiency and safety in those spaces; (2) to simulate different scenarios using the pedestrian simulation model LEGION; (3) to propose planning and design guidelines for pedestrian spaces at metro–bus interchanges; and (4) to contrast the recommendations in the recently opened terminal station on Line 1 of Metro de Santiago: Los Dominicos Station. 相似文献
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Nicholas B. Taylor 《运输规划与技术》2018,41(1):37-57
ABSTRACTPredicting the risk of traffic demands and delays exceeding critical limits at road junctions, airports, hospitals, etc., requires knowing how both mean and variance of queue size vary over time. Microscopic simulation can explore variability but is computationally demanding and gives only sample results. A computationally efficient approximation to the mean is used in many modelling tools, but only empirical extensions for variance in particular situations have been available. The paper derives theoretical formulae for time-dependent and equilibrium variance, believed to be novel and to apply generally to queues covered by the Pollaczek–Khinchin mean formula, and offering possible structural insights. These are applied in an extended approximation giving mutually consistent mean and variance estimates with improved accuracy. Tests on oversaturated peak demand cases are compared with Markov probabilistic simulation, demonstrating accuracy (R2?>?0.99) for typical random, priority-like (M/M/1) and traffic-signal-like (M/D/1) queues. Implications for risk analysis, planning and policy are considered. 相似文献