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Numerical investigation of effect of a centrifugal boost impeller on suction performance of an aircraft hydraulic pump

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Chinese Journal of Aeronautics 2022年第8期35卷 236-248页

作者： Hongkang DONG yongling he Yan WANG Guiyue KOU School of Transportation Science and Engineering Beihang UniversityBeijing 100083China School of Mechanical and Electrical Engineering Nanchang Institute of TechnologyNanchang 330099China

An integrated boost impeller can effectively improve the suction performance of an aircraft hydraulic pump(AHP).It must be designed very carefully;however,few studies thus far have investigated boost *** explore the effect of the boost impeller,this study developed a three-dimensional computational fluid dynamics(CFD)model for an AHP based on the k-εturbulence model and full cavitation *** results of verification tests demonstrated that the model is reliable for simulating the delivery characteristics of piston pumps and the boost capacity of the inlet ***-state simulations reveal that the boost impeller can remarkably improve the suction performance and mitigate the cavitation damage due to insufficient fluid filling while only consuming a small proportion of the total input ***-state simulations show that the pump with an impeller is more capable of catching up with a sudden increase in flow demand,and it has a lower suction flow ripple and ***,such a boost impeller also has some limitations such as magnifying the suction pressure fluctuation and having little effect on mitigating the cavitation caused by the back-flow jet.

关键词： Aircraft hydraulic pump Cavitation Computational Fluid Dynamics Impeller Suction performance Transient flow

Mechanisms of Accelerated Degradation in the Front Cells of PEMFC Stacks and Some Mitigation Strategies

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Chinese Journal of Mechanical Engineering 2013年第6期26卷 1250-1258页

作者： LI Pengcheng PEI Pucheng he yongling YUAN Xing CHAO Pengxiang WANG Xizhong School of Transportation Science and Engineering Beihang University State Key Laboratory of Automotive Safety and Energy Tsinghua University

The accelerated degradation in the front ceils of a polymer electrolyte membrane fuel cell（PEMFC） stack seriously reduces the reliability and durability of the whole stack. Most researches only focus on the size and configuration of the gas intake manifold, which may lead to the maldistribution of flow and pressure. In order to find out the mechanisms of the accelerated degradation in the front cells, an extensive program of experimental and simulation work is initiated and the results are reported. It is found that after long-term lifetime tests the accelerated degradation in the front cells occurs in all three fuel cell stacks with different flow-fields under the U-type feed configuration. Compared with the rear cells of the stack, the voltage of the front cells is much lower at the same current densities and the membrane electrode assembly（MEA） has smaller active area, more catalyst particle agglomeration and higher ohmic impedance. For further investigation, a series of three dimensional isothermal numerical models are built to investigate the degradation mechanisms based on the experimental data. The simulation results reveal that the dry working condition of the membrane and the effect of high-speed gas scouting the MEA are the main causes of the accelerated degradation in the front cells of a PEM fuel cell stack under the U-type feed configuration. Several mitigation strategies that would mitigate these phenomena are presented： removing cells that have failed and replacing them with those of the same aging condition as the average of the stack; choosing a Z-type feed pattern instead of a U-type one; putting several air flow-field plates without MEA in the front of the stack; or exchanging the gas inlet and outlet alternately at a certain interval. This paper specifies the causes of the accelerated degradation in the front cells and provides the mitigation strategies.

关键词： Proton exchange membrane fuel cell Degradation mechanism Mitigation strategy

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基于CEEMDAN分解的风电功率预测方法

科学技术创新 2024年第22期 89-92页

作者：冬鑫陈秋雨高俊何永玲韦厚盛北部湾大学广西钦州上汽通用汽车有限公司上海

为了解决由于风电中出现的随机性和波动性对风电功率预测造成的预测精度不高的问题,提出了一种基于CEEMDAN的风电功率预测方法。首先,使用CEEMDAN算法对风电功率进行信号分解,然后,在LSTM算法的基础上,使用Encoder-Decoder框架,结合Atte... 详细信息

为了解决由于风电中出现的随机性和波动性对风电功率预测造成的预测精度不高的问题,提出了一种基于CEEMDAN的风电功率预测方法。首先,使用CEEMDAN算法对风电功率进行信号分解,然后,在LSTM算法的基础上,使用Encoder-Decoder框架,结合Attention机制,设计了ELDGAWP风电功率预测模型,有效解决了LSTM在处理非常长的序列数据时,模型可能会遇到梯度消失的问题,最后将各模态分量预测结果累加得到最终预测结果。经与现有模型进行对比,本文所提C-ELDGAWP预测方法的预测精度最高。

关键词： CEEMDAN LSTM 预测风电

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怀念陈朝璧、周枏两位法学泰斗

比较法研究 2007年第4期21卷 143-148页

作者：何永龄夏门大学法学院

我是1944年考入厦门大学法律系学习，当年系主任是周柑教授。陈朝璧教授也在系里教书。后来，抗战胜利，周柑教授转赴上海暨南大学法律系任教并兼任系主任，陈朝璧教授继续留在厦大任教并转任教务长及系主任。当时厦大法律系学生不多，... 详细信息

我是1944年考入厦门大学法律系学习，当年系主任是周柑教授。陈朝璧教授也在系里教书。后来，抗战胜利，周柑教授转赴上海暨南大学法律系任教并兼任系主任，陈朝璧教授继续留在厦大任教并转任教务长及系主任。当时厦大法律系学生不多，我们班里一共有22位同学，所有上课都是小班。两位教授的教学丰采和博泛的精彩论述，同学们感受至深，受益也最多。几十年过去了，我们回忆往昔学习的日子，仍然历历在目。

关键词：怀念法学法律系系主任厦门大学暨南大学学习同学

A Wideband High-Gain Sawtooth Slot Array Antenna with Frequency-Scanning at Lower Frequency and Fixed-Beam at Higher Frequency

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Chinese Journal of Electronics 2024年第2期33卷 463-471页

作者： Qiang SUN yongling BAN Jun HU School of Electronic Science and Engineering University of Electronic Science and Technology of China

Exploring the multifunctional array antenna suitable for complex communication environment has very important research value. In this paper, a millimeter wave(mm-wave) double longitudinal sawtooth slot array antenna(DLSA) based on substrate integrated waveguide(SIW) technology is proposed, which has wideband, highgain and novel beam characteristics. Two irregular longitudinal slots are etched on the SIW conductor surface as the radiation structure. To improve the bandwidth of the DLSA, the metallized vias are added at the transition point of the slots to construct multiple resonant frequency points. By adjusting the size of the slots and the position of the metallized vias, the phase constant can be regulated, and the unusual beam characteristics can be obtained. That is to say, in the lower frequency band, the beam pointing angle increases with frequency. In the higher frequency band,the beam pointing angle is maintained at a fixed angle. Finally, to improve the antenna gain, a 16 × 8 DLSA is fabricated, measured and discussed. The proposed antenna has an impedance matching bandwidth close to 9.7 *** 27 to 33 GHz, the beam pointing angle changes from 8° to 29°. From 33 to 37 GHz, the beam pointing angle is fixed at 29°, and the pointing angle error range is ±1°. In addition, the measured maximum gain is 22.9 d Bi at32 GHz.

关键词： Antenna measurements Slot antennas Surface waves Resonant frequency Gain measurement Conductors Frequency measurement

Two-phase Flow of Liquid-gas in Diesel Fuel Injection System and Their Effect on Engine Performances

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Journal of Thermal Science 2001年第3期10卷 223-227页

作者： yongling he ,Zhihe Zhao ,Jianxin Liu ,Huiyong Du Mm Li ,Yongping Zong Luoyang Institute of Technology, Luoyang 471039, China E-mail: frick@*** Luoyang Institute of Technology Luoyang China

In this paper, by using high-speed camera, CCD camera, signal and graph acquisition system, and other experimental instruments, investigation on liquid-gas two-phase flow in diesel fuel injection system and their effect on engine performances were made. Emerging and bursting of cavitation in the cavity above pump delivery valve, in injection pipe, and in fuel trough of injector of the fuel injection system were observed and mechanism of cavitation were discussed. Effects of liquid-gas two-phase flow on propagation velocity of pressure wave of the system and on irregular injection were analyzed. Two types of cavitation, long Living time cavitation and short living time cavitation, in the cavity above pump delivery valve of diesel fuel injection system were observed.

关键词： diesel engine two-phase flow in fuel injection system irregular injection.

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气泡模型在喷油系统模型仿真中的应用

农业工程学报 2011年第3期27卷 142-146页

作者：何勇灵李汝宁北京航空航天大学交通科学与工程学院北京100191

为了更准确预测喷油系统中压力脉动变化,引入了基于气泡溶解和析出的物理过程的气泡模型,将其应用到柴油机喷油系统模型中,并编制了喷油系统模型仿真程序。对含气率恒定和应用气泡模型的柴油机喷油系统分别进行仿真,并将仿真结果与试验... 详细信息

为了更准确预测喷油系统中压力脉动变化,引入了基于气泡溶解和析出的物理过程的气泡模型,将其应用到柴油机喷油系统模型中,并编制了喷油系统模型仿真程序。对含气率恒定和应用气泡模型的柴油机喷油系统分别进行仿真,并将仿真结果与试验数据进行了对比。对比结果表明:含气率恒定的喷油系统模型仿真结果曲线比较平滑,而应用了气泡模型的喷油系统模型中,由于气泡体积随着系统压力和时间而变化,尤其在压力大于45MPa后,气泡体积减小速度增大,造成压力出现震荡,仿真结果和试验数据更加吻合。该研究不仅验证了气泡模型应用在柴油机喷油系统仿真中的可行性,而且为以后气液两相条件下的柴油机喷油系统模拟研究提供了基础。

关键词：柴油机模型仿真喷油系统压力脉动

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两级热电单偶输出性能的三维有限元分析

哈尔滨工业大学学报 2015年第9期47卷 79-83页

作者：何勇灵周岷峰北京航空航天大学交通科学与工程学院北京100191 北京市清洁能源与高效动力工程中心北京100191

针对以往研究中热电单偶一维传热模型的不足,提出了一种新型的两级热电单偶,对传统热电单偶和两级热电单偶分别建立三维有限元模型,确定模型的温度,对流换热和电势边界面,设定合理的边界条件,在ANSYS Workbench环境中进行仿真分析.应用... 详细信息

针对以往研究中热电单偶一维传热模型的不足,提出了一种新型的两级热电单偶,对传统热电单偶和两级热电单偶分别建立三维有限元模型,确定模型的温度,对流换热和电势边界面,设定合理的边界条件,在ANSYS Workbench环境中进行仿真分析.应用控制变量法,研究不同输入变量对两种热电单偶各自输出性能的影响并进行比较分析.结果表明:负载值大小影响输出电压和电流,当负载值小于某个临界值时,两级热电单偶的输出电压和电流优于传统热电单偶,而最大输出功率始终大于传统热电单偶.

关键词：两级热电单偶传统热电单偶三维有限元模型控制变量法输出性能仿真

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一种分布式驱动电动汽车操纵稳定性控制算法

汽车工程 2014年第2期36卷 129-133页

作者：冯冲丁能根何勇灵北京航空航天大学交通科学与工程学院北京100191

针对四轮轮毂电机独立驱动、四轮线控转向电动汽车的过驱动系统,以提高汽车的操纵稳定性为目标,提出了一种基于伪逆控制分配的控制算法。该算法以驾驶员对转向盘和加速踏板的操纵量为输入,通过伪逆控制分配,对汽车的前、后轮转角,4个车... 详细信息

针对四轮轮毂电机独立驱动、四轮线控转向电动汽车的过驱动系统,以提高汽车的操纵稳定性为目标,提出了一种基于伪逆控制分配的控制算法。该算法以驾驶员对转向盘和加速踏板的操纵量为输入,通过伪逆控制分配,对汽车的前、后轮转角,4个车轮的驱动力进行控制。在Matlab/Simulink仿真环境下采用8自由度非线性车辆模型对所提出的算法,进行了正弦输入工况和双移线工况的仿真,并与采用常规控制方法时进行对比。结果表明,伪逆控制分配算法提高了汽车对驾驶员驾驶意图的跟随性能,并改善了汽车的稳定性。

关键词：过驱动系统伪逆控制分配跟随性能稳定性