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A Reliability Assessment Framework for Cloud Applications
作者 Xiaowei Wang,Jens Grabowski
出版年份 2015 引用
摘要
Cloud computing enables users to use computing resources, platforms and applications with reduced deployment and maintenance cost. The reliability of cloud applications becomes one of the key c...展开全文
Cloud computing enables users to use computing resources, platforms and applications with reduced deployment and maintenance cost. The reliability of cloud applications becomes one of the key concerns of cloud service providers and users. Meanwhile, the deep dependency stack of layered cloud objects makes it challenging to evaluate the reliability of cloud applications. To tackle this problem, we propose a layered dependency graph-based reliability assessment framework. To verify our framework, we conduct an initial case study which shows its feasibility.
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Tire–road friction coefficient estimation based on the resonance frequency of in-wheel motor drive system
作者 Long Chen,Mingyuan Bian,Yugong Luo,Zhaobo Qin,Keqiang Li
出版年份 2015 引用
摘要
In this paper, a resonance frequency-based tire–road friction coefficient (TRFC) estimation method is proposed by considering the dynamics performance of the in-wheel motor drive system under ...展开全文
In this paper, a resonance frequency-based tire–road friction coefficient (TRFC) estimation method is proposed by considering the dynamics performance of the in-wheel motor drive system under small slip ratio conditions. A frequency response function (FRF) is deduced for the drive system that is composed of a dynamic tire model and a simplified motor model. A linear relationship between the squared system resonance frequency and the TFRC is described with the FRF. Furthermore, the resonance frequency is identified by the Auto-Regressive eXogenous model using the information of the motor torque and the wheel speed, and the TRFC is estimated thereafter by a recursive least squares filter with the identified resonance frequency.Finally,the effectiveness of the proposed approach is demonstrated through simulations and experimental tests on different road surfaces.
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V2I-Based Multi-Objective Driver Assistance System for Intersection Support
作者 Jianqiang Wang,Jiaxi Liu, Xiaohui Qin, Keqiang Li
出版年份 2014 引用
摘要
Vehicle driving assistance systems that recognize traffic signals can enhance driving safety, and improve driving comfort and smoothness at intersections. This study presents a configuration of Inte...展开全文
Vehicle driving assistance systems that recognize traffic signals can enhance driving safety, and improve driving comfort and smoothness at intersections. This study presents a configuration of Intersection Driver Assistance Systems (IDAS) and an algorithm of multi-objective IDAS for intersection support, which includes the two functions for driving support and traffic signal violation avoidance warning. Firstly, the system structure is designed and the assistance strategy is developed. To provide IDAS with the necessary information, an estimation method of vehicle driving status based on Kalman filtering and a relative positioning method between the vehicle and intersection based on Radio-Frequency Identification (RFID) beacons is proposed. In relation to a safety assistance strategy, this chapter presents a passing support algorithm based on critical passing speed and a dynamic traffic signal violation warning algorithm with multiple levels based on velocity threshold. Then the two algorithms are matched with various driving scenarios at intersections. The effects of IDAS on intersection driving are analyzed by random traffic simulation and field tests. The results show that besides the function of enhancing safety, the proposed IDAS can reduce deceleration times and increase passing rates at intersections, and therefore improve driving comfort and smoothness.
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Car2X technology-based “Green Light on Demand” system
作者 Yougang Bian, Jianqiang Wang, Bin Huang, Keqiang Li, Sheng Lai, Carsten Isert
出版年份 2014 引用
摘要
Car2X technology helps obtain information about individual vehicles, which acts as an accurate data resource for determining traffic status from the viewpoint of a tra...展开全文
Car2X technology helps obtain information about individual vehicles, which acts as an accurate data resource for determining traffic status from the viewpoint of a traffic signal controller designing phase timing. Based on Car2X technology, a prototype system for “Green Light on Demand,” which means adapting traffic signal automatically for privileged vehicles if necessary, is developed. Two types of passing algorithms for privileged vehicles at a single intersection are proposed. The first algorithm was tested by conducting a field experiment, and the result demonstrates that the system can reduce the number of stops for privileged vehicles. The second algorithm was tested in a simulation experiment, the results of which prove that the signal control algorithm can reduce the travel time and number of stops for privileged vehicles, while not having any significant effect on normal vehicles.                                                                            
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基于车路协同的车辆状态估计方法
作者 谢伯元,王建强,秦晓辉,李克强
出版年份 2014 引用
摘要
提出了一种基于车路协同的车辆质心侧偏角估计方法。该方法通过专用短程通信技术获取路侧基站的差分 GPS 信息,在车辆运动学模型的基础上,通过建立二次卡尔曼滤波器,融合差分 GPS 的航向角、车速和车载传感器的纵...展开全文
提出了一种基于车路协同的车辆质心侧偏角估计方法。该方法通过专用短程通信技术获取路侧基站的差分 GPS 信息,在车辆运动学模型的基础上,通过建立二次卡尔曼滤波器,融合差分 GPS 的航向角、车速和车载传感器的纵向加速度、横向加速度与横摆角速度信号,来估计车辆横摆角和质心侧偏角,并进行了实验验证。结果表明,即使在横向加速度较大的情况下,该方法仍具有较好的估计精度,可满足车路协同系统中车辆安全控制的要求。
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DGPS-based Vehicle State Estimation in V2I Cooperative System
作者 Boyuan Xie,Sifa Zheng,Xiaohui Qin,Xijun Zhou
出版年份 2013 引用
摘要
A sideslip angle estimation algorithm based on DGPS in V2I cooperative system is proposed. The vehicle kinematic model is built to estimate vehicle yaw angle and sideslip angle; meanwhile ...展开全文
A sideslip angle estimation algorithm based on DGPS in V2I cooperative system is proposed. The vehicle kinematic model is built to estimate vehicle yaw angle and sideslip angle; meanwhile a two-order kalman filter is used to fuse information from different sources. The first order kalman filter is available for processing lateral acceleration, longitudinal acceleration and yaw rate collected by IMU (inertia measurement unit); this information is used as the time update of vehicle model. The second order kalman filter is utilized to fuse vehicle location heading angle, which are collected by DGPS in cooperative system. This information is used as the measurement update of vehicle model. Steady-state cornering test results show that the algorithm is effective, even if the vehicle is in high lateral acceleration. The algorithm suits vehicle safety control requirements in V2I cooperative system.
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Intelligent Vehicle Platform and Signal Processing Method Applied to Cooperative Vehicle Infrastructure.
作者 Sibo Tian,Sifa Zheng,Boyuan Xie,Xiaohui Qin
出版年份 2013 引用
摘要
The technology of intelligent cooperative vehicle infrastructure helps to improve road traffic safety and efficiency. The intelligent vehicle platform is the key equipment for research and validation...展开全文
The technology of intelligent cooperative vehicle infrastructure helps to improve road traffic safety and efficiency. The intelligent vehicle platform is the key equipment for research and validation of the technology of intelligent cooperative vehicle infrastructure. First, the general requirements of intelligent vehicle platform as well as the platform vehicle motion and the way of gaining status information based on external sensors are introduced with a focus on the signal filtering and calibration of vehicle sensors. The intelligent vehicle platform established is demonstrated to gain status information of vehicle motion accurately through a comparison test and becomes the key device for the intelligent cooperative vehicle infrastructure research.
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