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On the Relatively Small Impact of Deep Dependencies on Cloud Application Reliability
作者 Xiaowei Wang,Fabian Glaser,Steffen Herbold,Jens Grabowski
出版年份 2017 引用
摘要
Reliability is one of the key concerns of both cloud providers and consumers, who require accurate reliability evaluation methods to develop, deploy, and maintain cloud applications. However, few...展开全文
Reliability is one of the key concerns of both cloud providers and consumers, who require accurate reliability evaluation methods to develop, deploy, and maintain cloud applications. However, few works assess the reliability of cloud applications considering deep dependencies in the deployment stack. To explore the impact of deep dependencies to the reliability assessment, in this paper, we propose a layered dependency graph-based reliability assessment method for cloud applications. By introducing the inner reliability of cloud components, and combining the deep dependencies between services and physical servers, the method can assess the reliability of all components as well as the application. We implement a framework for the method and compare the assessment results of our approach against existing methods. The results show that deep dependencies have few impacts on the accuracy while can improve the precision of reliability assessment methods because the failure rate of physical servers is much lower than software components.
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Estimation of tire-road friction coefficient based on frequency domain data fusion
作者 Long Chen,Yugong Luo,Mingyuan Bian,Zhaobo Qin,Jian Luo,Keqiang Li
出版年份 2017 引用
摘要
Due to the noise of sensing equipment, the tire states, such as the sideslip angle and the slip ratio, cannot be accurately observed under the conditions with small acceleration, which results in the...展开全文
Due to the noise of sensing equipment, the tire states, such as the sideslip angle and the slip ratio, cannot be accurately observed under the conditions with small acceleration, which results in the inapplicability of the time domain data based tire-road friction coefficient(TRFC) estimation method. In order to overcome this shortcoming, frequency domain data fusion is proposed to estimate the TRFC based on the natural frequencies of the steering system and the in-wheel motor driving system. Firstly, a relationship between TRFC and the steering system natural frequency is deduced by investigating its frequency response function (FRF). Then the lateral TRFC is determined by the steering natural frequency which is only identified using the information of the assist motor current and the steering speed of the column. With spectral comparison between the steering and driving systems, the data fusion is carried out to get a comprehensive TRFC result, using the different frequency information of the longitudinal and lateral value. Finally, simulations and experiments on different road surfaces validated the correctness of the steering system FRF and the effectiveness of the proposed approach.
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A New Powertrain Design Approach For Power-Split Hybrid Tracked Vehicles
作者 Zhaobo Qin,Yugong Luo,Keqiang Li,Huei Peng
出版年份 2017 引用
摘要
Powertrain design for power-split hybrid vehicles using planetary gears has been widely researched. As proved, the total number of candidate designs is large due to the diversity of connection ways...展开全文
Powertrain design for power-split hybrid vehicles using planetary gears has been widely researched. As proved, the total number of candidate designs is large due to the diversity of connection ways between devices and planetary gears. In this paper, a new powertrain design approach is developed and applied to power-split hybrid tracked vehicles. The three-step approach that uses constraint-based configuration selection, automated dynamic modeling, drivability screening and fuel economy screening can further reduce computation load and rapidly converge to superior designs. A case study is conducted to identify better designs compared with current designs for hybrid tracked dozers.
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Optimal Design of a Novel Hybrid Electric Powertrain for Tracked Vehicles
作者 Zhaobo Qin,Yugong Luo,Keqiang Li,Huei Peng
出版年份 2017 引用
摘要
Tracked vehicles have been widely used in construction, agriculture, and the military. Major problems facing the industry, however, are high emissions and fuel consumption. Hybrid electric tracke...展开全文
Tracked vehicles have been widely used in construction, agriculture, and the military. Major problems facing the industry, however, are high emissions and fuel consumption. Hybrid electric tracked vehicles have thus become increasingly popular because of their improved fuel economy and reduced emissions. While the series hybrid system has drawn the most attention and has been applied in most cases, the low efficiency caused by energy conversion losses and large propulsion motors has limited its development. A novel multi-mode powertrain with two output shafts controlling each side of the track independently is first proposed. The powertrain is a three-planetary-gear power-split system with one engine, three motors, and an ultracapacitor pack. Compared with the existing technologies, the proposed powertrain can realize skid steering without an extra steering mechanism, and significantly improve the overall efficiency. To demonstrate the advantages of the novel powertrain, a topology-control-size integrated optimization problem is solved based on drivability, fuel economy, and cost. Final simulation results show that the optimized design with downsized components can produce about a 30% improvement in drivability and a 15% improvement in fuel economy compared with the commonly used series hybrid benchmark. Moreover, the optimized design is verified to be much more economical taking cumulative cost into account, which is very attractive for potential industrial applications in the future.
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Optimal design of power-split hybrid tracked vehicles using two planetary gears
作者 Zhaobo Qin,Yugong Luo,Keqiang Li,Ziheng Pan,Huei Peng
出版年份 2017 引用
摘要
Power-split hybrid powertrains have been thus far successfully used for production passenger cars and SUVs but not for tracked vehicles.  For example, track-type dozer (TTD) models avail...展开全文
Power-split hybrid powertrains have been thus far successfully used for production passenger cars and SUVs but not for tracked vehicles.  For example, track-type dozer (TTD) models available on the market tend to use series hybrid powertrains, which frequently require a separate steering mechanism, resulting in lower operating efficiency and the need for large space arrangements. Looking to the future, power-split hybrid technologies have high potential for tracked vehicles to circumvent the limitation. This paper proposes a design process for multi-mode power-split powertrains for TTDs. The powertrain consists of one engine, two motors, and two outputs connected independently to the left and right tracks. This powertrain is designed to achieve separate control of the two sides of the tracks to enable skid steering.  In addition, multi-mode ensures that the powertrain can realise central steering and driving backwards using the engine power. To systematically search for all possible designs with two planetary gears, an optimal methodology is proposed. By establishing two characteristic matrices, an automated modelling  process is proposed to obtain the dynamic equations quickly and efficiently.  A near-optimal energy management strategy call PEARs+ is used to achieve near-optimal fuel economy. The approach successfully identifies two designs that achieve better overall performance compared with the benchmark.
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Dynamic coordinated control of a downhill safety assistance system for hybrid electric buses
作者 Zhaobo Qin,Donghao Zhang,Yunwu Han ,Yugong Luo
出版年份 2017 引用
摘要
When driving downhill, downhill safety assistance control can ensure a safe speed. A downhill safety assistance system was developed by our research group to help hybrid electric vehicles to maint...展开全文
When driving downhill, downhill safety assistance control can ensure a safe speed. A downhill safety assistance system was developed by our research group to help hybrid electric vehicles to maintain a stable speed when driving downhill. For hybrid electric buses, in addition to the pneumatic braking system, the motor can quickly provide an electrical braking torque, and the engine can be considered a mechanical brake. The downhill safety assistance system for hybrid electric buses maintains the desired downhill speed on different road slopes. However, when and how to activate or deactivate the downhill safety assistance system because of the driver’s operation or the road conditions was not discussed in combination with the energy management strategy for the vehicle. Additionally, there is currently no dynamic control strategy for the transition process when the braking modes of the downhill safety assistance system change, which can lead to instability. To address the limitations of previous studies, a dynamic coordinated control strategy of the downhill safety assistance system is proposed considering practical application, which focuses on the above two aspects to keep the entire system stable. To improve the ride comfort and the vehicle safety when the downhill safety assistance system works in conjunction with the energy management strategy for the vehicle, the proposed control strategy is developed to activate or deactivate the downhill safety assistance system based on the driver’s driving habits and operation and the road conditions in order to reduce the workload and to improve the driveability of the buses. To maintain the ride comfort during the transient process of shift in the braking mode and to maintain a stable speed over the overall course, the mode-shift coordinated control strategy of the downhill safety assistance system is presented, which combines the braking modes to ensure that the braking torque changes steadily without saltation. The experimental results validate the performance of the entire dynamic coordinated control strategy of the downhill safety assistance system with a high stability, and the statistics demonstrate that the downhill safety assistance system obviously improves the fuel economy and reduces the driver workload.
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液压混合动力履带推土机行星齿轮传动系统的设计
作者 秦兆博,罗禹贡,张东好,陈龙,李克强
出版年份 2017 引用
摘要
为提升液压混合动力履带车辆综合传动效率,以履 带推土机为例,提出了一种传动系统设计方案。搭建表征行 星传动系统动力学特征的矩阵。分别依据物理可行性、系统 特性对动力学特征矩阵进行筛选,对比现有履带推土机的 直...展开全文
为提升液压混合动力履带车辆综合传动效率,以履 带推土机为例,提出了一种传动系统设计方案。搭建表征行 星传动系统动力学特征的矩阵。分别依据物理可行性、系统 特性对动力学特征矩阵进行筛选,对比现有履带推土机的 直线行驶及转向性能筛选出更优的结构。根据履带推土机 典型循环工况,运用全局动态规划方法确定燃油经济性最优结构方案。结果表明:相比于现有的液压传动方案,该方案提升了牵引性能、转向性能及燃油经济性。
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自适应驾驶员行为特征的车道偏离防范系统
作者 胡满江,边有钢,许庆,徐彪,丁洁云,李克强
出版年份 2017 引用
摘要
提出一种能自适应驾驶员行为特征的车道偏离防范控制方法。基于驾驶员自然驾驶行为和人机交互行为数据库,提出自适应调节的动态期望驾驶区间与车道虚拟边界,以之为基础确定了车道偏离防范的决策参数,设计了车道偏离防范的决...展开全文
提出一种能自适应驾驶员行为特征的车道偏离防范控制方法。基于驾驶员自然驾驶行为和人机交互行为数据库,提出自适应调节的动态期望驾驶区间与车道虚拟边界,以之为基础确定了车道偏离防范的决策参数,设计了车道偏离防范的决策和分步控制策略,采用学习型模型预测控制理论构建自适应驾驶员行为特征的LDP控制器,以驾驶模拟器为平台进行驾驶员在环实验。结果表明,所提出的车道偏离防范方法能提高驾驶员对LDP控制的接受度。
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