大数据分析技术在新能源汽车行业的应用综述——基于新能源汽车运行大数据

为应对化石能源危机和环境污染问题,新能源汽车技术的发展与应用引起广泛重视。新能源汽车具有高信息化的特点和智能网联化的发展趋势,在日常运行中会产生大量行驶数据信息。利用海量多源异构数据进行安全预警与监管、车辆技术分析,是推动我国新能源汽车行业发展的关键。综述了大数据分析技术在新能源汽车行业的应用情况,概述了大数据分析技术的基础理论、发展历程,介绍了新能源汽车国家监测与管理平台的架构和功能,并着重阐述了新能源汽车大数据分析过程。分别从动力电池数据、汽车运行数据和充电数据的角度出发,分析了现有的研究方向和研究方法,列举了部分研究成果和应用情况。最后,对当前新能源汽车大数据分析领域存在的问题和发展应用前景进行了总结和展望。     

Experimental study on self-acceleration characteristics of unstable flame of low calorific value gas blended with hydrogen

The self-acceleration characteristics of cellular flame of low calorific value (LCV) gas in a constant volume combustion bomb were studied, the propagation process of spherical flame with different hydrogen (H₂) addition and initial pressure was analyzed, and the flame radius versus time was also discussed. The experimental results show that the self-acceleration of the cellular flame of LCV gas blended with hydrogen appears at high pressure, high hydrogen ratio and lean burn. The acceleration index increases with the increase of hydrogen addition and the reduction of equivalence ratio, and increases with the increase of initial pressure, but the acceleration index does not infinitely increase with the increase of initial pressure. With the increase of the hydrogen addition and the reduction of the equivalence ratio, the critical radius of the cellular flame decreases, which is shown that increase of the hydrogen addition and the lean burn will make appearance of cellular flame in advance. When the ratio of hydrogen is less than 60%, the critical Peclet number decreases with increase of hydrogen addition, when the ratio of hydrogen continues to increase to 80%, it increases slightly. The research in this paper provides an experimental basis for the in-depth study of engine combustion of LCV gas blended with hydrogen.     

An investigation into the heat release and emissions from counterflow diffusion flames of methane/dimethyl ether/hydrogen blends in air

In the present work, the effects of blending dimethyl ether (DME) and hydrogen (H₂) with methane (CH₄) have been numerically studied in the context of counterflow diffusion flames. In order to do so, a reaction mechanism consisting of 974 reaction steps among 146 species with updated thermodynamic and transport properties has been developed. This mechanism has been validated against the experimental data on laminar burning velocity, ignition delay time and species profiles in counterflow diffusion flames. The present study suggests that the heat release pattern of the CH₄ counter flow diffusion flame shows major changes when DME and H₂ are present in the fuel stream. Furthermore, the results show that the presence of low volume fractions of DME in CH₄ increases the formation of benzene (C₆H₆) in the flame. This fact can be negated by the presence of H₂ together with CH₄ and DME in the fuel stream. Moreover, the present study suggests that H₂ mitigates the C₆H₆ formation in the CH₄ diffusion flame with greater effectiveness compared to DME. Contrary to the popular belief, the main reason behind such efficacy of H₂ has been found to be physical rather than chemical. On the other hand, the NO production routes are primarily dominated by the Zeldovich mechanism in the flames involving CH₄, DME and H₂ blends. In this regard, the present analysis suggests that the simultaneous presence of DME and H₂ in CH₄ effectively prevents the formation of NO in the flame.     

Voltage response and two-phase flow during mode switching from fuel cell to water electrolyser in a unitized regenerative fuel cell

Mode switching operations between fuel cell (FC) and water electrolysis (WE) modes are indispensable to unitized regenerative FCs. Complicated electrochemical reactions and product transformations occur in the cell during mode switching. Thus, identifying dynamic behaviors during this procedure can improve cell durability and system design. In this study, the dynamic behaviors of cell voltage and electrochemical reaction during the switch from the FC mode to the WE mode are experimentally investigated. Reactant switching time significantly affects the electrochemical reactions. The water pumped into the cell in the FC mode reduces the cell voltage to a negative value and results in a hydrogen evolution reaction at the oxygen electrode side. Before FC mode voltage rapid decrease caused by supplied water, current transition could efficiently avoided the hydrogen evolution reaction at oxygen side. Ensuring that the moment water reaches the channels is close to the moment of current transition can improve the stability of unitized regenerative FCs.     

Geo-encryption protocol for mobile networks

We propose a geo-encryption protocol that allows mobile nodes to communicate securely by restricting the decryption of a message to a particular location and time period. Our protocol will handle the exchange of movement parameters, so that a sender is able to geo-encrypt messages to a moving decryption zone that contains a mobile node’s estimated location. We also present methods for estimating the node’s movement parameters to allow for geo-encryption. Finally, we evaluate our model by measuring the induced overhead to the network and its performance in terms of decryption ratio.     

Field assisted sintering of ceramic constituted by alumina and yttria stabilized zirconia

We show that a two-phase 50 vol% 3YSZ-alumina ceramic flash-sinters at a furnace temperature of 1060 °C under an electrical field of 150 V cm⁻¹. In contrast undoped, single-phase alumina remains immune to field assisted sintering at fields up to 1000 V cm⁻¹, although single-phase 3YSZ flash sinters at 750 °C (furnace temperature). The mechanisms of field assisted sintering are divided into two regimes. At low fields the sintering rate increases gradually (FAST), while at high fields sintering occurs abruptly (FLASH). Interestingly, alumina/zirconia composites show a hybrid behavior such that early sintering occurs in FAST mode, which is then followed by flash-sintering. The specimens held in the flashed state, after they had sintered to near full density, show much higher rate of grain growth than in conventional experiments. These results are in contrast to earlier work where the rate of grain growth had been shown to be slower under weak electrical fields.     

Optimal robust control of a contactless brake system using an eddy current

As vehicle speed increases, a more powerful brake system is required to ensure vehicle safety and its reliability. A contactless eddy current brake (ECB) is developed to take the superior advantages of fast anti-lock braking to the conventional hydraulic brake systems. Braking torque analysis is performed by using an approximate theoretical model and the model is modified through experiments to have a more reliable result. Designs of an ECB for a scaled model for demonstration and actual vehicle model are performed. Optimal torque control which minimizes a braking distance is achieved by maintaining a desired slip ratio corresponding to the road condition. Optimal controller which is robust to the varying road friction coefficients is designed by using a sliding mode controller. Simulation and experimental results for a scaled model are presented to investigate the performance of a contactless ECB.     

FeOOH/Ni heterojunction nanoarrays on carbon cloth as a robust catalyst for efficient oxygen evolution reaction

Developing catalysts based on transition metal-based materials for oxygen evolution reaction (OER), which are cheap and efficient, is one of the keys to increase the rate of electrolysis of water to produce hydrogen. Herein, we successfully synthesize iron hydr(oxy)oxide nano-arrays on carbon cloth (FeOOH@CC), and then metallic nickel is electrodeposited on its surface to fabricate FeOOH/Ni heterojunction nanoarrays. Notably, the optimal FeOOH/Ni heterojunction nanoarrays catalyst shows high electrocatalytic performance toward OER with a small overpotential of 257.8 mV at 50 mA cm⁻², a Tafel slope of 30.8 mV dec⁻¹ and outstanding long-term stability in alkaline media. The superior OER performance could be ascribed to the introducing of metallic nickel. The nickel in-situ grows on the surface of FeOOH, which not only can improve the conductivity of FeOOH, but also cooperate with FeOOH to form the FeOOH/Ni heterogeneous interfaces for further enhancing OER electrocatalytic activities. This work provides a simple and efficient strategy of interface engineering to fabricate oxyhydroxide/metal heterojunction nanoarrays as high-efficiency OER catalysts.     

Investigation of hydrogen storage on Sc/Ti-decorated novel B24N24

Inspired by the TM−N₄ coordination environment in single-atom catalysts, four novel TM-decorated B₂₄N₂₄ (TM = Sc, Ti) fullerenes with six TM−N₄ or TM−B₄ units are designed. Molecular dynamic simulations confirm that the four TM₆B₂₄N₂₄ fullerenes are thermodynamically stable. Their hydrogen storage properties were investigated using density functional theory calculations. Sc/Ti atoms bind to the N₄/B₄ cavities with an average interaction energy of 6.30–11.96 eV. Hence, the problem of clustering can be avoided. 36H₂ could be adsorbed with average hydrogen adsorption energies of 0.18–0.55 eV. The lowest hydrogen desorption temperatures at atmospheric pressure for Sc₆B₂₄N₂₄(N₄)–36H₂, Sc₆B₂₄N₂₄(B₄)–36H₂, Ti₆B₂₄N₂₄(N₄)–36H₂, and Ti₆B₂₄N₂₄(B₄)–36H₂ are 255 K, 318 K, 243 K, and 408 K, respectively. The maximum hydrogen gravimetric densities of the Sc₆B₂₄N₂₄ and Ti₆B₂₄N₂₄ systems are 7.74 wt% and 7.50 wt%, respectively. Therefore, the novel Sc₆B₂₄N₂₄ and Ti₆B₂₄N₂₄ could be suitable as potential hydrogen storage materials at ambient temperature.     

Combined Control Allocation and Sliding Mode Control in the Dynamic Control of a Vehicle with Eight In-Wheel Motors

An eight wheel independently driving steering (8WIDBS) electric vehicle is studied in this paper. The vehicle is equipped with eight in-wheel motors and a steer-by-wire system. A hierarchically coordinated vehicle dynamic control (HCVDC) system, including a high-level vehicle motion controller, a control allocation, an inverse tire model and a lower-level slip/slip angle controller, is proposed for the over-actuated vehicle system. The high-level sliding mode vehicle motion controller is designed to produce desired total forces and yaw moment, distributed to longitudinal and lateral forces of each tire by an advanced control allocation method. And the slip controller is designed to use a sliding mode control method to follow the desired slip ratios by manipulating the corresponding in-wheel motor torques. Evaluation of the overall system is accomplished by sine maneuver simulation. Simulation results confirm that the proposed control system can coordinate among the redundant and constrained actuators to achieve the vehicle dynamic control task and improve the vehicle stability.