Integrated energy-oriented cruising control of electric vehicle on highway with varying slopes considering battery aging

Eco-driving strategies for vehicles with conventional powertrains have been studied for years and attempt to reduce fuel consumption by optimizing the driving velocity profile. For electric vehicles(EVs) with regenerative braking, the speed profile with the best energy efficiency should be different from conventional vehicles. This paper proposes an energy-oriented cruising control strategy for EVs with a hierarchical structure to realize eco-cruising on highways with varying slopes. The upper layer plans the energy-optimized vehicle velocity, and the lower layer calculates the torque allocation between the front and rear axles.However, the resulting speed profile with varying velocity may cause a high charge and discharge rate of the battery, resulting in rapid battery fading. To extend the battery life, we make a tradeoff between the energy consumption and wear of the battery by formulating an optimal control problem, where driving comfort and travel time are also considered. An indirect optimal control method is implemented to derive the optimal control rule. As an extension, the control rule for avoiding rear-end collisions is presented and simulated for driving in the real world.     

Meta photonic crystal paper devices

Science China Technological Sciences -     

数控成形磨床移动式立柱温度特性分析及数据拟合

为了研究数控成形磨床中腰导轨移动式立柱温度场特性,采用LabVIEW(laboratory virtual instrument engineeringworkbench)虚拟仪器开发温度实时采集系统,对中腰导轨移动式立柱执行温度场测量,并基于测量数据对立柱进行热态特性分析;根据对温度场数据的分析和研究,针对时间常数跨度较大的多阶指数函数,提出一种逐级递推式拟合算法。根据不同时间常数的指数函数具有不同平衡时间的特点,通过数学变换,采用一阶指数函数的拟合算法进行拟合并逐级递推,分别得到多阶指数函数不同项的时间常数和相应的幅值。拟合曲线与试验曲线相比,此算法简单实用,并具有较高的拟合精度,适合用于移动式立柱温度特性分析与精确建模。     

意美公司信息管理系统设计与实现

对意美公司信息管理系统需求进行了分析,构建以库存管理为核心的采购、入库、销售、出库一体化的信息管理系统。对开发中的关键问题,给出了解决方案,效果良好。     

Ratcheting boundary of 316LN austenitic stainless steel under thermal aging

Science China Technological Sciences - Previous studies, including ASME and RCC-MR standards, did not consider the influence of environmental factors on the ratcheting boundary of the material, and...     

Squeeze film air damping ratio analysis of a silicon capacitive micromechanical accelerometer

Microsystem Technologies - The dynamics behavior of most micro-electro-mechanical-system (MEMS) devices is significantly affected by the squeeze-film air damping. Therefore, the correct prediction...     

A framework for rapid on-board deterministic estimation of occupant injury risk in motor vehicle crashes with quantitative uncertainty evaluation

Accurate on-board occupant injury risk prediction of motor vehicle crashes(MVCs) can decrease fatality rates by providing critical information timely and improving injury severity triage rates. The present implemented prediction algorithms in vehicle safety systems are probabilistic and rely on multi-variate logistic regression of real-world vehicle collision databases. As a result,they do not utilize important vehicle and occupant features and tend to overgeneralize the solution space. This study presents a framework to address these problems with deterministic and computationally efficient lumped parameter model simulations driven by a database of vehicle crash tests. A 648-case mixed database was generated with finite element and multi-body models and validated under the principal directions of impact with experimental results for a single vehicle body type. Using the finite element database, we developed lumped parameter models for four principal modes of impact(i.e., frontal, rear, near side and far side) with parameters identified via genetic algorithm optimization. To obtain confidence bounds for the injury risk prediction,the parameter uncertainty and model adequacy were evaluated with arbitrary and bootstrapped polynomial chaos expansion. The developed algorithm was able to achieve over triage rates of 17.1% ± 8.5%, whilst keeping the under triage rates below 8% on a finite element-multi body model database of a single vehicle body type. This study demonstrated the feasibility and importance of using low-complexity deterministic models with uncertainty quantification in enhanced occupant injury risk prediction. Further research is required to evaluate the effectiveness of this framework under a wide range of vehicle types. With the flexibility of parameter adjustment and high computational efficiency, the present framework is generic in nature so as to maximize future applicability in improved on-board triage decision making in active safety systems.     

Elucidating the operating behavior of PEM fuel cell with nickel foam as cathode flow field

Metal foam material, which serves as an alternative replacement of the conventional flow distributor of proton exchange membrane(PEM) fuel cell, has been attracting much attention over last few decades. In this work, three-dimensional modeling work for PEM fuel cell containing metal foam as cathode flow distributor has been carried out. The fuel cell performance and operating characteristics of metal foam flow field and conventional parallel flow channel have been compared and discussed.The cell performance has been reasonably validated based on the corresponding experimental tests conducted in this study. The superior performance of PEM fuel cell with metal foam as cathode flow field benefits a lot from the uniform gas flow. The porous metal foam material provides more pathways for the water delivery at the interface of metal foam flow field and gas diffusion layer(GDL), accelerating water removal capability of cathode. Because of the significant oxygen transfer loss in diffusion limited parallel channel, the operation of PEM fuel cell with parallel channel is found to be more sensitive to cathode humidification and oxygen supply at inlet. Due to the more uniform and effective electron transport though the porous electrode, it is possible to use thinner GDL in metal foam PEM fuel cell. It is expected that this study could give a good baseline of operating behavior of PEM fuel cell with metal foam flow distributor.