基于CAD与CFD的穿梭艇局部船型特征分析

穿梭艇船型是一种针对恶劣航行条件下的高速船艇需求提出的,具有内倾式船首的、单体、高速、穿浪、排水型船。论文基于CAD和CFD技术,对影响穿梭艇在静水中阻力和兴波性能的首尾部若干局部船型特征进行了对比分析,揭示了不同船型特征下的穿梭艇性能特性间的差异,为以后相关船型的设计开发提供了有益的参考。     

柴油机共轨电控燃油喷射技术

电子控制技术是车用柴油机燃油喷射系统发展的必然趋势,而目前开发的共轨电控燃油喷射系统是发展的主流,其分为高压共轨系统和中压共轨系统两类,本文介绍该两类系统的基本结构和原理,并阐述共轨系统的现状及发展方向。     

LNG-FPSO单点系泊系统特性研究

LNG-FPSO具有开采、处理、液化天然气的功能,并可储存和装卸LNG,由单点系泊系统长期系泊于作业海域。基于BV系泊分析软件ARIANE7.0.2,采用时域计算方法分析了预张力和系泊缆长度等参数对系泊缆最小安全系数和最大躺底长度的影响,结论为系泊系统的优化提供了一定的参考。     

A statistical process control approach using cumulative sum control chart analysis for traffic data quality verification and sensor calibration for weigh-in-motion systems

Weigh-in-motion systems have been widely used by state agencies to collect the traffic data on major state roadways and bridges to support traffic load forecasting, pavement design and analysis, infrastructure investment decision making, and transportation planning. However, the weigh-in-motion system itself poses difficulties in obtaining accurate data due to sensor characteristics that can be sensitive to vehicle speed, weather conditions, and changes in surrounding pavement conditions. This study focuses on developing a systematic methodology to detect weigh-in-motion sensor bias and enhance current practices for weigh-in-motion calibration. A mixture modeling technique using an expectation maximization algorithm was developed to divide the vehicle class 9 gross vehicle weight into three normally distributed components: unloaded, partially loaded, and fully loaded trucks. Then the well-known statistical process control technique cumulative sum control chart analysis was applied to expectation maximization estimates of daily mean gross vehicle weight for fully loaded trucks to identify and estimate shifts in the weigh-in-motion sensor. Special attention was given to the presence of autocorrelation in the data by fitting an autoregressive time-series model and then performing cumulative sum control chart analysis on the fitted residuals. Results from the analysis suggest that the proposed methodology is able to estimate a shift in the weigh-in-motion sensor accurately and also indicate the time point when the system went out of calibration. This methodology can be effectively implemented by state agencies, resulting in more accurate and reliable weigh-in-motion data.