Influence of rail pressure on a two-stage turbocharged heavy-duty diesel engine under transient operation

The demand for continually improving the transient performance of diesel engines requires higher rail pressure and more efficient turbocharger. Before the test, a two-stage turbocharger with a turbine by-pass valve (TBV) had been matched reasonably with the base engine. In order to reduce smoke emission under the typical 5-second transient process of constant speed and increasing torque, the influence of rail pressure on combustion, emissions and performance characteristics was experimentally investigated. The results showed that the two-stage turbocharger was helpful in improving transient performance. Moreover, the full-stage rail pressure (FSRP) strategies (increasing rail pressure during the whole transient process) could reduce smoke emission when the TBV was closed. However, smoke deteriorated once TBV opening got larger. Then the sectional-stage rail pressure (SSRP) strategies (increasing rail pressure from a pre-set load to 100 % load) were presented under small TBV opening to improve in-cylinder thermal condition. Hence, the air-fuel mixing process was improved at medium and large loads. Then the maximum decline of smoke opacity peak was 56.3 %, which happened under 10 % TBV opening. In addition, fuel consumption of FSRP strategies got worse under larger TBV opening. However, this deterioration situation could be effectively restrained by the utilization of SSRP strategies.     

Development of jacket platform tsunami risk rating system in waters offshore North Borneo

This work details the simulation of tsunami waves generated by seaquakes in the Manila Trench and their effect on fixed oil and gas jacket platforms in waters offshore North Borneo. For this study, a four-leg living quarter jacket platform located in a water depth of 63m is modelled in SACS v5.3. Malaysia has traditionally been perceived to be safe from the hazards of earthquakes and tsunamis. Local design practices tend to neglect tsunami waves and include no such provisions. In 2004, a 9.3M _w seaquake occurred off the northwest coast of Aceh, which generated tsunami waves that caused destruction in Malaysia totalling US$ 25 million and 68 deaths. This event prompted an awareness of the need to study the reliability of fixed offshore platforms scattered throughout Malaysian waters. In this paper, we present a review of research on the seismicity of the Manila Trench, which is perceived to be high risk for Southeast Asia. From the tsunami numerical model TUNA-M2, we extract computer-simulated tsunami waves at prescribed grid points in the vicinity of the platforms in the region. Using wave heights as input, we simulate the tsunami using SACS v5.3 structural analysis software of offshore platforms, which is widely accepted by the industry. We employ the nonlinear solitary wave theory in our tsunami loading calculations for the platforms, and formulate a platform-specific risk quantification system. We then perform an intensive structural sensitivity analysis and derive a corresponding platform-specific risk rating model.     

基于生物电信号的驾驶疲劳检测方法

驾驶疲劳检测技术是当前安全辅助驾驶技术的一个研究热点,其中基于生物电信号的检测方法最直接。本文主要介绍驾驶疲劳的生成机理、检测方法的分类和基于脑电、心电、眼电和肌电等主要生物电信号检测方法的研究现状。最后,针对当前研究领域的不足给出了建议,以供研究者参考。     

Development of a path planning system using mean shift algorithm for driver assistance

The longitudinal and lateral vehicle control techniques have been widely used in several active driver assistance systems. The adaptive cruise control, lane keeping assistant control, vehicle platooning and stop-and-go control are typical examples of the most important applications. In this study, a novel path planning method is proposed considering the driving environment such as road shape, ego vehicle and surrounding vehicles’ movement. The relative distance and velocity between the ego vehicle and surrounding vehicles are identified with respect to the predicted lane shape in front of the ego vehicle. Based on the identified information, the road shape and surrounding vehicles are mapped into the intensity image and the desired vector for the ego vehicle’s movement is determined by the maximum intensity density tracing method. The desired vehicle path is followed by the acceleration/deceleration control and the steering assist control, respectively. In order to evaluate the performance of the proposed system, simulations are conducted and compared with ACC systems.     

高速公路特殊路基设计

以武罐高速公路路基设计为背景,简要论述公路工程地质在特殊路基设计过程中所起的重要作用,可供同行参考和借鉴。     

基于有限元方法的发动机悬置强度改进设计

为解决某车辆发动机悬置橡胶撕裂破坏问题,建立了该发动机悬置的有限元模型,计算所得悬置的垂向刚度与试验结果基本吻合,验证了该模型的有效性。静态模型和动态模型计算结果表明,橡胶垫内部应力集中出现在受力面转角处。对悬置模型进行结构改进,并对改进前、后的试件进行了刚度测量试验和疲劳寿命试验。结果表明,改进后发动机悬置垂向静刚度比原悬置降低了7.5%;静刚度变化率和压缩永久变形量分别为规定限值的32%和6%。     

涪陵青草背长江大桥主缆无应力长度计算

主缆无应力长度的计算是悬索桥上部结构施工监控顺利进行的有效保证.利用通用软件Midas/Civil对涪陵青草背长江大桥建立有限元模型,进而修正索股无应力长度,提出采用通用软件建立悬索桥模型并计算主缆无应力长度的一般方法,为采用该类通用软件计算悬索桥主缆的无应力长度提供参考.     

连续泊位调度与岸桥配置协同优化

连续泊位调度与岸桥配置协同优化是集装箱码头提升竞争力的关键因素.针对该问题构建一个混合整数规划模型,以构造算法为核心,通过调整船舶的分配次序,设计了一个新的启发式算法.通过VB6.0软件编程,进行了四组大规模仿真算例实验,结果显示60%的算例在新算法下可获得更优的解,平均改进7.37%,证明了模型和算法的有效性.     

中缅油气管道码头工程水动力泥沙研究

工程位于缅甸西部的马德岛东北侧水域。在现场实测水文、泥沙、地貌等资料分析的基础上,依据码头和航道设计方案,利用整体潮流物理模型、ADCP走航式测试方法及波浪潮流泥沙数学模型等手段,对工程海域的水沙环境、码头前沿水域的流态及航道开挖抛泥区的选择等工程建设的关键要素进行了综合研究。结果表明:码头前水域涨、落潮水流都较为平顺,在该处修建码头是可行的;在选划的抛泥区A、B、C三区内抛泥,对航道基本没有影响,是安全经济合理的。     

复杂地形条件下波浪爬坡数值模拟研究

波浪爬高是确定海堤、护岸等海岸工程顶高程的主要因素,不仅直接影响工程造价,更关系到工程的安全。目前,针对单一型缓坡以及坡度较陡的防波堤的研究较多,但兼顾各种复杂地形条件下的波浪爬坡还没有一种公认较好的计算模型。文中首次采用MIKE21一维BW模型,分别通过规则波和不规则波对波浪破碎以及波浪爬坡进行了数物模验证。结果表明,应用MIKE21一维BW模型不仅能模拟在缓坡上的波浪破碎及爬坡过程,也能模拟诸如防波堤等陡坡的波浪爬高现象。将该模型应用于海南昌江核电护岸工程,为其安全性设计提供了科学依据,同时也为复杂地形条件下的波浪爬坡问题提供了一种切实可行、易于推广的研究方法。