Optimization Control of Multi-Mode Coupling All-Wheel Drive System for Hybrid Vehicle

The all-wheel drive(AWD)hybrid system is a research focus on high-performance new energy vehicles that can meet the demands of dynamic performance and passing ability.Simultaneous optimization of the power and economy of hybrid vehicles becomes an issue.A unique multi-mode coupling(MMC)AWD hybrid system is presented to realize the distributed and centralized driving of the front and rear axles to achieve vectored distribution and full utilization of the system power between the axles of vehicles.Based on the parameters of the benchmarking model of a hybrid vehicle,the best model-predictive control-based energy management strategy is proposed.First,the drive system model was built after the analysis of the MMC-AWD’s drive modes.Next,three fundamental strategies were established to address power distribution adjustment and battery SOC maintenance when the SOC changed,which was followed by the design of a road driving force observer.Then,the energy consumption rate in the average time domain was processed before designing the minimum fuel consumption controller based on the equivalent fuel consumption coefficient.Finally,the advantage of the MMC-AWD was confirmed by comparison with the dynamic performance and economy of the BYD Song PLUS DMI-AWD.The findings indicate that,in comparison to the comparative hybrid system at road adhesion coefficients of 0.8 and 0.6,the MMC-AWD’s capacity to accelerate increases by 5.26%and 7.92%,respectively.When the road adhesion coefficient is 0.8,0.6,and 0.4,the maximum climbing ability increases by 14.22%,12.88%,and 4.55%,respectively.As a result,the dynamic performance is greatly enhanced,and the fuel savings rate per 100 km of mileage reaches 12.06%,which is also very economical.The proposed control strategies for the new hybrid AWD vehicle can optimize the power and economy simultaneously.

Modal analysis of coupled vibration of belt drive systems

The modal method is applied to analyze coupled vibration of belt drive systems. A belt drive system is a hybrid system consisting of continuous belts modeled as strings as well as discrete pulleys and a tensioner arm. The characteristic equation of the system is derived from the governing equation. Numerical results demenstrate the effects of the transport speed and the initial tension on natural frequencies.

Mode switching control strategy of dual motors coupled driving on electric vehicles

Based on analyzing the structure and working principle on electric vehicles （EVs） with dual motors coupled by planetarY gears, the control strategy of mode switching was proposed. The power interruption problem on EVs with automatic mechanical transmission （AMT） shifting was resolved. Based on the speed-torque characteristics of the planetary gears and the principle of the auxiliary motor＇ s zero speed braking, control features of mode switching were introduced. The mode shifting between the main motor mode and dual motors coupled driving were studied. Matlab/Simulink was adopted as a platform to develop the simulation model of EVs with dual motors drive system and 3 gears AMT. Simulation results demonstrated that the power interruption of dual motors drive system was solved during mode switching. The power requirements of EVs were satisfied, too.

Frequency dependence of plasma characteristics at different pressures in cylindrical inductively coupled plasma source

The effects of driving frequency on plasma parameters and electron heating efficiency are studied in cylindrical inductively coupled plasma(ICP) source. Measurements are made in an Ar discharge for driving frequency at 13.56/2 MHz, and pressures of 0.4-1.2 Pa. In 13.56 MHz discharge, higher electron density(n_e) and higher electron temperature(T_e) are observed in comparison with 2 MHz discharge at 0.6-1.2 Pa. However, slightly higher n_e and T_e are observed in 2 MHz discharge at 0.4 Pa. This observation is explained by enhanced electron heating efficiency due to the resonance between the oscillation of 2 MHz electromagnetic field and electron-neutral collision process at 0.4 Pa. It is also found that the variation of T_edistribution is different in 13.56 and 2 MHz discharge.For ICP at 13.56 MHz, T_eshows an edge-high profile at 0.4-1.2 Pa. For 2 MHz discharge, T_e remains an edge-high distribution at 0.4-0.8 Pa. However, the distribution pattern involves into a center-high profile at 0.9-1.2 Pa. The spatial profiles of n_e remain a center-high shape in both 13.56 and 2 MHz discharges, which indicates the nonlocal kinetics at low pressures. Better uniformity could be achieved by using 2 MHz discharge. The effects of gas pressure on plasma parameters are also examined. An increase in gas pressure necessitates the rise of n_e in both 13.56 and 2 MHz discharges. Meanwhile, T_e drops when gas pressure increases and shows a flatter distribution at higher pressure.

Double Position Servo Synchronous Drive System Based on Cross-Coupling Integrated Feedforward Control for Broacher

Synchronization errors directly deteriorate the machining accuracy of metal parts and the existed method cannot keep high synchronization precision because of external disturbances. A new double position servo synchronous driving scheme based on semi-closed-loop cross- coupling integrated feedforward control is proposed. The scheme comprises a position error cross-coupling feedfor-ward control and a load torque identification with feed- forward control. A digital integrated simulation system for the dual servo synchronous drive system is established. Using a 20 t servo broacher, performance analysis of the scheme is conducted based on this simulation system and the simulation results show that systems with traditional parallel or single control have problems when the work- table works with an unbalanced load. However, the system with proposed scheme shows good synchronous perfor- mance and positional accuracy. Broaching tests are performed and the experimental results show that the maximum dual axis synchronization error of the system is only 8μm during acceleration and deceleration processes and the error between the actual running position and the given position is almost zero. A double position servo synchronous driving scheme is presented based on crosscoupled integrated feedforward compensation control, which can improve the synchronization precision.

Effect of driving frequency on electron heating in capacitively coupled RF argon glow discharges at low pressure

A one-dimensional（1D） fluid model on capacitively coupled radio frequency（RF） argon glow discharge between parallel-plates electrodes at low pressure is established to test the effect of the driving frequency on electron heating. The model is solved numerically by a finite difference method. The numerical results show that the discharge process may be divided into three stages： the growing rapidly stage, the growing slowly stage, and the steady stage. In the steady stage,the maximal electron density increases as the driving frequency increases. The results show that the discharge region has three parts： the powered electrode sheath region, the bulk plasma region and the grounded electrode sheath region. In the growing rapidly stage（at 18 μs）, the results of the cycle-averaged electric field, electron temperature, electron density, and electric potentials for the driving frequencies of 3.39, 6.78, 13.56, and 27.12 MHz are compared, respectively. Furthermore,the results of cycle-averaged electron pressure cooling, electron ohmic heating, electron heating, and electron energy loss for the driving frequencies of 3.39, 6.78, 13.56, and 27.12 MHz are discussed, respectively. It is also found that the effect of the cycle-averaged electron pressure cooling on the electrons is to ＂cool＂ the electrons; the effect of the electron ohmic heating on the electrons is always to ＂heat＂ the electrons; the effect of the cycle-averaged electron ohmic heating on the electrons is stronger than the effect of the cycle-averaged electron pressure cooling on the electrons in the discharge region except in the regions near the electrodes. Therefore, the effect of the cycle-averaged electron heating on the electrons is to ＂heat＂ the electrons in the discharge region except in the regions near the electrodes. However, in the regions near the electrodes, the effect of the cycle-averaged electron heating on the electron is to ＂cool＂ the electrons. Finally, the space distributions of the electron pressure cooling the electron ohmic heating and the electron heating at 1/4 T, 2/4 T, 3/4 T, and 4/4 T in one RF-cycle are presented and compared.

A Comprehensive Evaluation Framework of Water-Energy-Food System Coupling Coordination in the Yellow River Basin,China

For mankind’s survival and development,water,energy,and food(WEF)are essential material guarantees.In China,however,the spatial distribution of WEF is seriously unbalanced and mismatched.Here,a collaborative governance mechanism that aims at nexus security needs to be urgently established.In this paper,the Yellow River Basin in China with a representative WEF system,was selected as a case.Firstly,a comprehensive framework for WEF coupling coordination was constructed,and the relationship and mechanism between them were analyzed theoretically.Then,we investigated the spatiotemporal characteristics and driving mechanisms of the coupling coordination degree(CCD)with a composite evaluation method,coupling coordination degree model,spatial statistical analysis,and multiscale geographic weighted regression.Finally,policy implications were discussed to promote the coordinated development of the WEF system.The results showed that:1)WEF subsystems showed a significant imbalance of spatial pattern and diversity in temporal changes;2)the CCD for the WEF system varied little and remained at moderate coordination.Areas with moderate coordination have increased,while areas with superior coordination and mild disorder have decreased.In addition,the spatial clustering phenomenon of the CCD was significant and showed obvious characteristics of polarization;and 3)the action of each factor is self-differentiated and regionally variable.For different factors,GDP per capita was of particular importance,which contributed most to the regional development’s coupling coordination.For different regions,GDP per capita,average yearly precipitation,population density,and urbanization rate exhibited differences in geographical gradients in an east-west direction.The conclusion can provide references for regional resource allocation and sustainable development by enhancing WEF system utilization efficiency.

Numerical Investigation of Flow Structure Interaction Coupling Effects in Hard Disk Drives

This paper studies the flow structural interaction (FSI) within a hard disk drive (HDD) through the use of a novel coupling method. The interaction studied was the fluid induced vibration in the HDD. A two step coupling approach was used, where the fluid and structural components were solved sequentially. The result obtained was a ratio of 0.65 between the vibration amplitudes of a fixed head stack assembly (HSA) and a moving HSA. The ratio was next applied on a real 3.5 inch HDD, to allow the parameter to be further improved upon. A new benchmark index of 0.69 was developed from this. This parameter may allow future researchers to model the out of plane vibrations of a HSA easily, saving precious time. A 31% more accurate simulation of FSI within 3.5 inch HDD at 15000 rpm is achieved by the use of this new coupling method and benchmark index.

水资源-能源-粮食-生态系统耦合协调及驱动力分析

为加深对我国水资源、能源、粮食、生态系统协同演变趋势的认识,构建水资源-能源-粮食-生态多维系统指标体系,运用耦合协调度模型对我国2005—2020年水资源-能源-粮食-生态系统耦合协调度进行评价,并采用多因素归因分析法进行驱动力分析。结果表明:我国水资源-能源-粮食-生态系统耦合协调度从2005年的0.55增长到2020年的0.84,各地区耦合协调度从勉强协调发展水平过渡到中级协调发展水平,各子系统对耦合协调度上升的驱动分别经历了由粮食子系统到生态子系统再到水资源子系统主导的过程;能源子系统的贡献率虽然比较小,但是未来可能是各地区提升水资源-能源-粮食-生态系统多维系统协调发展水平的突破口。

珠三角地区近20年城镇化与景观生态安全耦合协调分析

针对城镇化进程加快导致的珠三角地区生态景观胁迫程度日趋严峻,亟需加强区域生态保护的现状,构建新型城镇化与景观生态安全的耦合协调模型,定量测度2000—2020年珠三角地区城镇空间扩展与景观生态安全耦合协调时空格局以及发展状态,运用多元回归分析和灰色预测模型揭示其驱动机理,并预测2040年城镇空间扩展和景观生态安全耦合的发展趋势。结果表明:珠三角地区9市城镇化与景观生态安全的耦合协调度在20年间呈现缓慢波动上升的趋势,耦合协调度由2000年的0.305~0.436升至2020年的0.385~0.545,现处于拮抗耦合阶段,未来20年将继续向着协调同步、有序发展的方向前进。珠三角地区经济发展不平衡,城镇开发建设和生态环境保护难以同步发展,景观生态状况不乐观,生态环境滞后型的地市逐渐增多,尚未全面形成良好的协调发展状态。对外开放程度、经济发展水平、科技投入水平等因素对耦合协调度的影响较为显著(P<0.05),今后对于区域可持续发展需要加强耦合协调的机理研究,持续关注城镇空间拓展与景观生态安全的协调发展趋势及特征。

谐波电流激励下电驱动系统振动特性及主动控制策略研究

为研究谐波电流激励下电驱动系统机电耦合振动特性及主动减振控制策略,以某电动汽车电驱动系统为研究对象,综合考虑电机本体结构特性、磁饱和特性、齿轮时变啮合刚度、啮合误差等非线性因素,建立了电驱动系统机电耦合动力学模型,研究了不同谐波电流激励下电驱动系统机电耦合振动特性。在此基础上,提出了基于谐波电流注入的电驱动系统主动减振控制策略,并通过离线辨识最优谐波电流参数。仿真结果表明:电磁激励与非线性机械激励耦合效应导致电磁转矩波动和相电流波形畸变,谐波电流激励加剧电机电磁转矩和齿轮传动系统振动幅值;基于谐波电流注入的电驱动系统主动减振控制策略作用下电机转矩波动及齿轮副动态啮合力6f_(e)、12f_(e)谐波分量幅值明显降低。

公众感知下重大传染病疫情冲击对社区韧性驱动因子独立、耦合作用及区域异质性分析

目的:探究公众感知下重大传染病疫情冲击对社区韧性驱动因子独立、耦合作用及区域特征,为后续精准施策提供理论依据。方法:采用网络调查法在我国东、中、西部各选一个省会城市展开调查,运用地理探测器和ESDA对社区韧性驱动因子进行探测并比较区域异质性特征。结果:政府公信力(0.322)、应急物品准备情况(0.297)是社区韧性的主导因子;任意两因子耦合对社区韧性的解释力均显著增强;各驱动因子对社区韧性的影响在空间上存在差异性,且“风险意识”“政府公信力”“家庭应急计划”是造成区域异质性的关键因子。结论:重大传染病疫情冲击下的社区韧性是多因子耦合作用的结果,多因子耦合对社区韧性的复杂影响需要多部门、多阶段、多机制因地制宜采取差异化的举措,全方位提升社区韧性。

考虑逆变器谐波耦合的牵引传动系统机电耦合振动特性研究

作为牵引传动系统能量转换的关键部件,牵引电机在电气激励作用下会受到各种冲击载荷和周期激振力的作用,从而产生机电耦合振动,威胁牵引传动系统的可靠运行。对此,基于双惯量模型对牵引传动系统机电耦合振动特性开展研究。首先,建立牵引电机的双惯量模型,依据此模型对其固有频率进行计算,并介绍了机械传动系统的同频受迫振动模态。其次,根据逆变器的开关特性,着重分析了脉宽调制(PWM)导致的边带谐波转矩对机电耦合同频共振的影响,探索逆变器的频率耦合产生的间谐波对机电耦合系统的影响。接着,以传递函数的形式对考虑双惯量负载的牵引传动系统进行建模,从频域角度对系统机电耦合共振特性进行理论分析。最后,利用硬件在环测试对所分析结果进行验证。

教育-科技-人才耦合协调度研究———基于30个省级区域的实证分析

本文运用耦合协调度模型、空间自相关分析和灰色关联度模型,探讨2010—2020年30个省区市(港澳台和西藏除外)教育、科技、人才的综合发展水平,以及三者的耦合协调度。研究发现:①教育、科技、人才各子系统的综合水平呈平稳增长态势,其中人才增长态势最好,教育增长态势次之,且各子系统间的发展差距逐渐减小;②三者的耦合协调度值逐年上升,从轻度失调转变为濒临失调,但区域发展不均衡,整体尚未达到融合发展的较优状态;③耦合协调度在省际层面呈显著的全局和局部自相关,空间俱乐部趋同特征明显;④根据重要性程度,驱动教育、科技、人才耦合协调的因素依次包括经济条件、产业发展、市场化程度、政府调控水平、人口规模等,但存在区域异质性。

考虑频率耦合特性的D-PMSG复数域阻抗建模及其特征分析

阻抗分析法因其简单有效被广泛用于含电力电子变换器的互联系统稳定性研究。然而,采用传统方法对频域序阻抗建模时,需通过非线性变换(Park变换及其反变换)进行坐标系转换,这会导致不同周期分量的卷积运算及相应的频移,其过程较为烦琐。针对上述问题,基于复向量时域微分算子,提出了永磁直驱同步发电机(D-PMSG)等效阻抗建模方法。该方法在时域周期系统稳定运行轨迹的邻域内直接进行小信号线性化,并采用指数旋转因子灵活反映系统受扰后的时变特性,结合时域微分算子等效表征互联系统控制环节的动态特性,避免了频域阻抗建模时坐标系的反复变换,大幅降低了解析建模的复杂度。此外,所提方法能够更加清晰地阐释互联系统受到扰动时D-PMSG并网逆变器产生频率耦合现象的物理意义;同时,能够说明基频电压初始相位对耦合分量相频特性的影响。最后,利用仿真验证了所提算法的有效性。

中国枢纽城市航空通达性与经济带动效应耦合协调实证研究

航空通达性是影响城市经济带动效应的关键因素,两者耦合协调发展是落实国家区域协调发展战略的重要举措。在测度中国39个枢纽城市2010—2019年航空通达性及经济带动效应基础上,就两者耦合协调关系进行定量分析。结果表明:(1)枢纽城市航空通达性呈现“纵向整体改善,横向两极分化”格局,且国际枢纽城市通达性水平明显高于区域枢纽城市;(2)枢纽城市经济带动效应同样呈现“纵向稳步提升,横向两极分化”态势,国际枢纽城市经济带动效应显著优于区域枢纽城市;(3)枢纽城市航空通达性与经济带动效应耦合协调度呈现“纵向波动上升,横向梯次分布”格局;(4)“经济带动效应领先”型和“航空通达性领先”型是两者耦合失调的主要类型。因此,未来应进一步提升枢纽城市间航空运输市场联系强度、扩大腹地市场规模,协同推进航空通达性与经济带动效应耦合协调发展,从而实现枢纽经济与区域经济深度融合。

长三角城市群基础设施与旅游经济耦合协调时空格局演变及驱动机制

以长三角城市群为研究对象,构设基础设施水平与旅游经济发展综合评价指标体系,采用耦合协调度模型探析二者耦合协调发展的时空演化特征,并运用地理探测器考察分析其驱动机制。结果表明:1)基础设施水平与旅游经济发展的综合评价指数、耦合协调度均呈稳步提升趋势,二者耦合协调类型介于中度协调与极度协调之间且较快地实现协调等级跃迁;耦合协调度省际差异显著,呈“上海市>江苏省>浙江省>安徽省”的空间异质性特征。2)耦合协调度呈“东高西低,中部高南北低”空间分布格局,且高、低耦合协调区分别呈空间“扩张-收敛”相背离的变化态势;考察期间基础设施滞后型城市数量逐渐增多,分布于长三角城市群东部浙沪地区;旅游经济发展滞后型城市分布范围逐渐收敛并向长三角北部聚集。3)基础设施水平与旅游经济发展耦合协调性主要受经济拉动力、政府调控力、城市化带动力作用,二者协调发展由8项驱动力形成的经济运行与结构转型机制、政策调控与开放合作机制、人口集聚与消费拉动机制、人才保障与科技创新机制综合驱动。

断块油藏注采耦合提高采收率机理及矿场实践

针对渤海湾盆地济阳坳陷东营凹陷古近系断块油藏水驱开发后期流线固定导致注入水无效循环的问题,基于渗流力学和油藏工程原理,通过室内物模模拟和油藏数值模拟,提出了“细分开发层系、轮注轮采”的注采耦合开发调整技术,并验证了该技术可提高采收率的原理。研究结果表明:(1)利用注采耦合开发技术建立的“注入期间的高渗通道与低渗通道吸水量比模型”和“采油期间主流线和非主流线产油量比模型”均揭示了“改变压力场促进渗流场调整,实现均匀注入和均匀采出,扩大水驱波及系数和增加驱油效率”的注采耦合渗流力学机制。(2)注采耦合技术可以实现“扩大波及系数、增加驱油效率”,起到类似“调剖”的作用,高含水期通过此项技术可将低渗透岩心的分流率由1.0%提到18.6%,模型驱替更均衡;经过2个轮次的注采耦合调整,高、低渗透岩心的原油采收率分别提高了10.3%和16.1%。(3)研究区D断块古近系沙河街组沙二段Es236含油小层油藏注采耦合开发数值模拟结果显示,主流线和非主流线驱替更均匀,两者压力梯度极差由2.3下降至1.4。经过3个轮次注采耦合开发调整,沙二段3—6砂层组油藏平均综合含水率下降了3.2%,累计增油1 760 t,提高原油采收率2.1%,增油降水效果显著。

长江经济带旅游经济-城镇化-生态环境耦合研究

旅游经济-城镇化-生态环境的耦合协调发展是长江经济带高质量发展的关键,探索三者之间的关系及其驱动因素具有重要意义。以长江经济带为研究区,构建旅游经济-城镇化-生态环境耦合协调发展评价指标体系,运用熵值法、耦合协调模型、OLS模型、GWR模型等,从时空视角探究长江经济带11个省市2012~2021年旅游经济-城镇化-生态环境耦合协调发展状况和驱动因素。结果表明:①2012~2019年长江经济带耦合协调度呈上升趋势,生态环境子系统起主导作用;2020~2021年的新冠疫情期间,耦合协调度先明显下降,后缓慢恢复。②长江经济带旅游经济-城镇化-生态环境耦合协调度呈现东高西低的空间格局,各省市综合评价水平、子系统评价水平得分的上升和恢复速度有明显差异,长江经济带总体向有序协调发展。③推动三系统协调发展的驱动因素总体可分为外部动力和内在动力,其中以入境游客人数为代表的外部动力和以水资源总量、工业废水排放量为代表的内部动力对长江经济带耦合协调的正向驱动作用最强。

基于鸟瞰图的多任务端到端3D目标检测方法

由于在自动驾驶过程中激光雷达扫描过程中受到空间限制,采集到的点云数据损失了过多的信息。在聚合表示方法的基础上,提出了基于鸟瞰图的多任务端到端3D目标检测方法。首先,利用纹理特征提取器与语义特征提取器对特征金字塔的高级特征层与低级特征层进行特征融合,获得扩展的特征金字塔层,使得自动驾驶过程中的中等目标(骑自行车的人)与小目标(行人)不再耦合在同一级别的特征金字塔层,提高了点云拓扑信息的区域细节性。其次,在损失函数中引入用于分类的Focal loss与用于回归的CIOU loss,改善了正负样本比例,对目标检测框进行了约束,使得目标框在回归过程中能够以更高精度收敛。实验结果表明,提出的方法在自动驾驶中小目标检测中具有更强的检测能力与更高的检测精度。