Performance evaluation of the inside intersection median-turn lane markings on the mobility and safety performance of signalized intersections in the Philippines and Japan

Signalized intersections are one of the key elements that play a vital role at road networks. The efficiency and safety levels of intersections can affect the operational performance of the whole system. In general, turning traffic, especially median-turning, has always been considered as the most problematic movement in the operation of intersections. This becomes more critical with high turning demand where exclusive turning lanes (single or double) can be assigned to provide larger capacities for these movements and to reduce conflicts with through traffic. However, improper treatment of median-turn lanes could create cross-maneuvering behavior which may limit the expected increase in capacity and create safety issues. Median-turning lane markings are commonly provided at intersections in Japan to guide drivers while turning which is expected to reduce the conflicts among turning traffic. Meanwhile, in the Philippines, exclusive median-turn lanes are installed at intersections without proper treatment which may contribute to the low mobility and safety levels. Therefore, this study evaluated the impact of inside intersection lane markings on the operation of median-turn lanes in terms of mobility and safety. The vehicle maneuver, speed and interactions between the turning traffic were utilized as essential components for the assessment. The empirical analysis shows that conflicting trajectories were present on double turn lanes without median-turn lane markings in the Philippines, which resulted to serious conflicts among the turning vehicles and negatively influenced the turning speed and saturation flow rate of the turn lanes. On the other hand, the turn lane markings in Japan, provided a positive impact to mobility and safety of the turning lanes. Moreover, it was also found that the geometric characteristics and traffic signal phasing scheme highly affects the capacity and safety condition of signalized intersections.     

蒸汽管道孔口泄放流量工程计算方法探究

常用的蒸汽管道孔口泄放流量计算方法是借助喷管流量计算公式,公式中的进口蒸汽比体积需借助蒸汽热力性质表换算,且低过热度时绝热指数采用经验值,得到的计算值与实际有偏差,此外,传统计算式的形式较为繁琐,这些因素在一定程度上影响了其在工程中的使用。为满足工程需求,完善蒸汽管道孔口泄放流量的工程计算方法,推导出一个适用于蒸汽状态、压力参数多变,便于工程设计分析的更为简便、准确的孔口泄放流量工程计算式,式中涉及的蒸汽状态参数易于测试,采用的温度修正因子则提高了公式在低过热度下使用的准确性。同时,结合工程实例,分析此计算式的使用情况,并认为,完善后的蒸汽管道孔口泄放流量计算式将在蒸汽管道孔口泄放问题中有更为广泛的应用。     

地质参数对地基承载力的影响以及土层穿刺评估

地质参数的正确选择对平台安全操作有重要意义。本文针对某自升式海洋平台所处南海海域地质土层,利用数值比较法对砂的内摩擦角以及粘土不排水抗剪强度等地质参数进行研究。通过地质参数前后系数的改变在地基承载力计算结果的体现,比较数值得出结论,并通过所画土层的地基承载力插桩曲线评估该土层发生穿刺危险的可能性。结果表明：采用将砂土内摩擦角降低5°、按实际的土层强度参数进行地基承载力计算和插桩深度预测,计算结果与实际平台操作结果接近以及选取1.5的安全系数计算和评估穿刺危险是可行的。     

利用极限质心高度的半潜船装载能力分析

结合某半潜船空载静水力数据和液舱的相关数据提出一种半潜船质心高度计算方法,然后根据半潜船的稳性变化曲线得到其稳性随吃水变化的控制点,通过对比半潜船的质心高度与极限质心高度来确定其装载大型沉箱及异形型沉箱的施工可行性,可进一步形成具有查询、计算功能的数据库为施工人员决策提供参考。     

粘贴碳纤维布与钢板加固RC梁的承载力计算方法

根据提出的加固材料强度系数,并基于试验数据分析,分别提出了粘贴碳纤维布和粘贴钢板加固钢筋混凝土梁的抗弯承载力提高系数计算公式。研究结果表明,粘贴钢板比粘贴碳纤维布对梁的抗弯承载力有更好的加固效果。     

基于FGU的船体变形测量技术中时间延迟补偿方法研究

基于光纤惯性测量单元(Fiber Gyro Unit,简称FGU)的角速率匹配法是船体变形测量技术的发展方向,但是在实际应用中两套测量单元之间存在时间延迟,会影响船体变形测量精度。该文分析了时间延迟的产生机理以及时间延迟对变形估计的影响。并基于二阶马尔科夫模型对船体变形建模,建立卡尔曼滤波状态方程和量测方程,提出了一种时间延迟补偿方法,将时间延迟扩充为状态量,对其进行实时的估计和补偿。最后通过仿真并结合实船试验数据,对比分析了时间延迟补偿前后的变形估计效果,验证了此方法的有效性。     

钢筋混凝土拱桥极限承载力的参数分析

采用空间有限元模型,研究了活荷载分布方式、拱圈混凝土的强度、拱圈面内的抗弯刚度、矢跨比和初始几何缺陷等参数对钢筋混凝土拱肋极限承载力的影响。研究结果表明:拱圈混凝土的强度、拱圈面内的抗弯刚度和矢跨比是决定大跨度钢筋混凝土拱桥极限承载力的3个关键设计参数;初始几何缺陷会降低结构的极限承载能力,但降低的程度很小,一般情况下可以忽略该参数的影响;矢跨比在一定范围内取值时,随着矢跨比的降低,钢筋混凝土拱桥的极限承载能力也随之减弱,且不同的矢跨比取值范围对极限承载力的影响程度不同。     

Optimal Age Replacement Policy with Replacement Occurrence While the Warranty is in Effect

This study considers an age replacement policy(ARP) for a repairable product with an increasing failure rate with and without a product warranty. As for the warranty policy to consider in association with such an age replacement policy, we adapt a renewable minimal repair-replacement warrant(MRRW) policy with 2D factors of failure time of the product and its corresponding repair time. The expected cost rate during the life cycle of the product is utilized as a criterion to find the optimal policies for both with and without the product warranty. We determine the optimal replacement age that minimizes the objective function which evaluates the expected cost rate during the product cycle and investigate the impact of several factors on the optimal replacement age. The main objective of this study lies on the generalization of the classical age replacement policy to the situation where a renewable warranty depending on 2D factors is in effect. We present some interesting observations regarding the effect of relevant factors based on numerical analysis.     

高原公路连续驾驶时间对驾驶员疲劳影响的分析

为研究在高原公路上行车时连续驾驶时间对驾驶员疲劳的影响,在帕米尔高原典型高原公路上进行行车试验。利用生物反馈仪,采集驾驶员连续驾驶过程中心率与心率变异指标。通过定性、定量相结合的方法分析连续驾驶时间对驾驶员疲劳的影响。研究结果表明:驾驶员在高原公路上连续驾驶70min左右会呈现疲劳状态。     

Oracle RAC和Times Ten性能研究

依据吞吐率这个性能评价指标,基于TPC-C测试基准,使用Swingbench对Oracle的RAC和Times Ten产品进行了性能测试,并对测试数据进行统计学分析。结果表明:RAC的性能与RAC节点数之间有极高的相关性,不同复制技术下的Times Ten性能有显著差异,其中基于读写分离的Times Ten有10倍单节结点RAC的吞吐率均值,性能最好。