Property Evolution of Sulphoaluminate Grouting Material under Pressure Circulation北大核心CSCD

Water-sealed underground oil tank projects are quite different from traditional underground projects since the water-sealing conditions are very strict and the difficulties caused by the geological specificity, structural specificity and construction specificity are key factors affecting the project. In light of the significant early initial setting time and rapid temperature increase of sulphoaluminate cement-based grouting material for a large domestic water-sealed underground oil tank with pressurized cyclic grouting, a laboratory grouting simulation is conducted. It is found that the properties of the sulphoaluminate cement-based grouting material are quite different under different pressure cycles, the hydration exothermic peak time gets shorter with an increase of circulation time, the compressive strength decreases with an increase of circulation time, and the longer the circulation time the more obvious the de-crease of compressive strength. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

柔性基层在东红路大修工程中的应用

认为柔性基层温湿变形小,可以防止水泥砼面板的开裂;具有较大的空隙率(一般>13%),可以迅速地排出由面板缝隙渗透下的雨水;也可以提高水泥砼路面的抗冲击、抗振性能及行车舒适性。用作沥青路面的联结层,可以提高抗车辙性能和减轻由于半刚性基层温缩裂缝而引起面层的反射裂缝。     

我国第3阶段摩托车排放标准研究与制定

制定我国第3阶段摩托车排放标准时,既要考虑我国摩托车工业现状,也要考虑最大限度地与国际统一法规接轨,相信标准的执行必将使我国摩托车企业增强环保意识,积极采用新技术,不断提高摩托车生产制造和研发能力及生产一致性控制能力,促进在用车法制化管理,把摩托车对环境的污染降低到较低水平,保护人类的生存和生活环境。     

跨学科的城市交通治理体系研究

随着新科技革命向纵深发展,"十四五规划纲要"对城市交通治理提出了新的要求,面向未来的城市交通治理研究重要性凸显.结合工业化、城镇化的发展趋势,从城市规模、技术发展、交通发展模式、风险应急管理、治理模式演化等方面归纳未来城市交通治理面临的挑战;梳理城市交通治理所需的跨学科知识以及理论基础;在"三元空间"分析视角下,构建以...     

空调压缩机提前失效的原因分析及改进措施

对客车空调压缩机提前失效进行原因分析,并提出改进措施。     

Fire Risk Quantitative Assessment of Offshore Supported Platform

The living area of an offshore platform is the main living place for operators in offshore oil and gas fields. Fire risk assessment plays an important role in t...     

斜拉法施工张拉模拟技术研究

为解决斜拉法施工大范围分级张拉工序复杂、受桥面临时荷载影响大等实际问题,依托"先斜拉—后悬索"工艺施工的某大跨度桥梁,详细计算张拉过程中斜拉索的引出量,并利用无应力状态法和传统计算中的预应力模拟分级张拉.研究结果表明:影响矩阵法计算张拉引出量精度较高且操作简单;"等效温差法"和"单元生死法"以无应力索长为控制指标,张拉...     

低浓度盐水异重流运动规律试验研究

船舶通过河口船闸将导致盐水潜入闸室继而侵入淡水河道造成水质恶化。既有研究集中于海船闸高浓度盐水入侵（浓度20‰~30‰）,但对于河口船闸低浓度盐水（浓度2.23‰~4.17‰）入侵过程及规律尚不清楚。基于室内大尺度水槽试验,研究了低浓度盐水的运动特性,探讨低浓度盐水运动形态的演变过程、盐度分布与盐水运动形态的关系、盐水头部运动速度以及密度弗劳德数与浓度的关系。结果表明,受密度梯度力驱动,低浓度盐水仍然作异重流运动并集中在底部输移;低浓度盐水异重流运动形态的转化距离相比高浓度盐水更远,其运动状态受底床阻力影响分为滑塌阶段和自相似阶段,密度弗劳德数在滑塌阶段为常数（FrH=0.32）、自相似阶段随时间线性递减（斜率为-0.01）。     

基于大数据的实际道路油耗研究与优化

文章借助大数据平台,以国内某款乘用车型为研究对象,提取了车型不同地区不同用户群体的油耗状态,分离出了高油耗客户群体油耗偏高的原因,有针对性地进行油耗优化和验证。通过大数据对比发现车辆实际道路工况及油耗与法规工况及油耗差异较大,文章通过实际道路设计进行油耗验证和分析,用更加贴近用户使用的工况分析油耗影响因素的敏感性,通过采取相应的降油耗措施达到降低实际使用油耗的目的。研究结果表明:高油耗客户群体的怠速工况占比较大;油耗对行驶平均车速、冷启动工况的敏感性较高;北方地区行驶工况恶劣是油耗偏高的主要原因;低温地区匹配雪地胎的油耗比匹配四季胎的油耗更好。     

SPH中改进无网格插值方法比较和精度分析(英文)

In the smoothed particle hydrodynamics (SPH) method, a meshless interpolation scheme is needed for the unknown function in order to discretize the governing equation. A particle approximation method has so far been used for this purpose. Traditional particle interpolation (TPI) is simple and easy to do, but its low accuracy has become an obstacle to its wider application. This can be seen in the cases of particle disorder arrangements and derivative calculations. There are many different methods to improve accuracy, with the moving least square (MLS) method one of the most important meshless interpolation methods. Unfortunately, it requires complex matrix computing and so is quite time-consuming. The authors developed a simpler scheme, called higher-order particle interpolation (HPI). This scheme can get more accurate derivatives than the MLS method, and its function value and derivatives can be obtained simultaneously. Although this scheme was developed for the SPH method, it has been found useful for other meshless methods.