The impacts of household features on commuting carbon emissions: a case study of Xi’an,China

Transportation - This study contributes to the analysis of the household characteristics and household neighborhood ones affecting the transportation carbon dioxide emissions produced by commuters....     

二维Walsh变换的快速算法设计

在分析二维Ｗａｌｓｈ函数的基础上,提高一类二维Ｗａｌｓｈ变换快速算法。这类算法快捷灵活,在图像处理,信号处理等领域有着广泛的应用。     

某型充电发电机可靠性试验系统设计与仿真

十二相整流充电发电机常应用于需要高品质直流电源的场所,充电发电机的可靠性试验可以为该型电机的运行状况、维护保养及确定修理周期提供科学依据。文章结合可靠性试验的基本理论,分析了充电发电机恒定应力加速可靠性试验方案,设计了发电机输出作为直流电动机电源的能量反馈试验拖动系统,并进行了基于PSCAD/EMTDC的可靠性试验系统的动态性能仿真分析。仿真结果表明能量反馈可靠性试验系统响应快、稳定性良好。     

基于ADAS联网时空数据的路段交通参数估算模型

交通参数实时获取是道路交通管控的重要基础.针对固定检测器观测范围受限和浮动车数量需求大的问题,研究了1种利用车载ADAS联网数据进行路段交通参数估算的方法.通过分析车载ADAS感知的前向目标参数与交通参数的关系,结合广义交通量定义,并考虑多车道条件下ADAS车辆及其邻近前车的相对运动变化特性,建立了1种非稳态交通条件下...     

新型开孔工字板组合式透空防波堤消浪特性数值模拟研究（英文）

Based on the three-dimensional Reynolds-averaged Navier-Stokes equation with the closure of renormalization group k-εturbulence model and volume of fluid method, a wave-breakwater interaction numerical flume was developed to examine the wave-structure interaction of the porous I-type composite(PITC) breakwater. The transmission and reflection coefficients of the breakwater at different wave steepness H/L are quantitatively analyzed, and the wave-dissipating performance of the breakwater is compa...     

多车道高速公路分流交织区交通流特性与交通组织策略

为了解决多车道高速公路分流交织区由于车道数增加、交通流量增加、标志设置不合理等原因存在的诸多安全问题,在分析多车道高速公路分流交织区存在的问题和总结现有多车道高速公路断面形式(整体式断面、客货分离式断面、主辅分离式断面)的基础上,提出多车道高速公路分流交织区的交通组织形式及其优缺点.总结了多位学者对多车道高速公路分流交...     

基于SVPWM永磁直线同步电机控制仿真与应用

直线电机能直线运动,以获得单向或双向的有限可控位移.合理的控制策略与系统设计是直线电机快速准确高效控制的关键.文章分析了永磁直线同步电机(PMLSM)的数学模型耦合特点,得到PMLSM仿真模型,并进行PMLSM空间矢量脉宽调制(SVPWM)的仿真分析.仿真结果表明SVPWM控制的有效性.设计了一种基于DSP的永磁直线同...     

Design of underwater robot lines based on a hybrid automatic optimization strategy

In this paper, a hybrid automatic optimization strategy is proposed for the design of underwater robot lines. Isight is introduced as an integration platform. The construction of this platform is based on the user programming and several commercial software including UG6.0, GAMBIT2.4.6 and FLUENT12.0. An intelligent parameter optimization method, the particle swarm optimization, is incorporated into the platform. To verify the strategy proposed, a simulation is conducted on the underwater robot model 5470, which originates from the DTRC SUBOFF project. With the automatic optimization platform, the minimal resistance is taken as the optimization goal;the wet surface area as the constraint condition; the length of the fore-body, maximum body radius and after-body＇s minimum radius as the design variables. With the CFD calculation, the RANS equations and the standard turbulence model are used for direct numerical simulation. By analyses of the simulation results, it is concluded that the platform is of high efficiency and feasibility. Through the platform, a variety of schemes for the design of the lines are generated and the optimal solution is achieved. The combination of the intelligent optimization algorithm and the numerical simulation ensures a global optimal solution and improves the efficiency of the searching solutions.     

高压逃生艇运动与乘员晕船率分析

高压逃生艇是饱和潜水系统中为潜水员配备的专用高气压紧急撤离设备,相比常压下的全封闭救生艇,具有大吃水、高重心和对乘坐舒适性的要求较高等特征。基于三维势流理论计算分析高压逃生艇的运动响应,在此基础上分析乘员晕船问题,得到艇体运动和艇员晕船率与航速和波浪条件之间的影响关系。研究发现：艇体垂荡、横摇和纵摇并不总是随航速的增加而加剧;艇体横摇和纵摇的峰值对应的遭遇周期分别为9 s和3 s;波浪从艇尾入射时,艇体的垂荡和纵摇相比波浪从艇首入射时更剧烈;艇上乘员的晕船率与波浪条件和航速相关,艇尾处的乘员晕船率最高。     

Dangerous driving behavior detection using video-extracted vehicle trajectory histograms

Dangerous driving behavior detection can be used in video surveillance systems to identify dangerous patterns, such as Abrupt Double Lane Change (ALC), Retrograde Driving (RD), and Illegal U-Turn (IT), for traffic design, traffic management, and law enforcement. The purpose of this study is to develop a detection method of dangerous driving behavior based on video surveillance. First, a novel method named trajectory histogram is proposed. A set of trajectory histograms (e.g., control points histogram and velocity histogram) is constructed to represent vehicle motion. Then, a frequently used feature selection method named Minimum Redundancy and Maximum Relevance (mRMR) is introduced to evaluate the most representative trajectory histograms for dangerous driving behavior detection. In addition, a hybrid algorithm, Particle Swarm Optimization-Support Vector Machine (PSO_SVM), is then developed to identify dangerous driving behavior. To validate the performance and effectiveness of the proposed method, several experiments are conducted. The results show that mRMR is better than other representative methods, namely Conditional Mutual Information Maximization (CMIM), Mutual Information Maximization (MIM), and ReliefF, for evaluating the most representative trajectory histograms. Based on the most representative trajectory histograms, the detection accuracy rate of dangerous driving behavior using PSO_SVM is superior to those of the most frequently used classifiers—Naïve Bayesian Classifier (NBC), k-Nearest Neighbor (kNN), and C4.5 decision tree. In addition, we find that the proposed method outperforms the two common approaches for dangerous driving behavior detection in video surveillance systems. Therefore, the proposed method can be widely applied to detect dangerous driving behavior in video surveillance systems.