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Investigation of the aeroacoustic behavior and aerodynamic noise of a high-speed train pantograph

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Science China(Technological Sciences) 2017年第4期60卷 561-575页

作者： zhang yadong zhang JiYe LI Tian zhang Liang State Key Laboratory of Traction Power Southwest Jiaotong University Chengdu 610031 China

As one of the main aerodynamic noise sources of high-speed trains, the pantograph is a complex structure containing many components, and the flow around it is extremely dynamic, with high-level turbulence. This study analyzed the near-field unsteady flow around a pantograph using a large-eddy simulation(LES) with high-order finite difference schemes. The far-field aerodynamic noise from a pantograph was predicted using a computational fluid dynamics(CFD)/Ffowcs Williams-Hawkings(FW-H) acoustic analogy. The surface oscillating pressure data were also used in a boundary element method(BEM) acoustic analysis to predict the aerodynamic noise sources of a pantograph and the far-field sound radiation. The results indicated that the main aerodynamic noise sources of the pantograph were the panhead, base frame and knuckle. The panhead had the largest contribution to the far-field aerodynamic noise of the pantograph. The vortex shedding from the panhead generated tonal noise with the dominant peak corresponding to the vortex shedding frequency and the oscillating lift force exerted back on the fluid around the ***, the peak at the second harmonic frequency was associated with the oscillating drag force. The contribution of the knuckle-downstream direction to the pantograph aerodynamic noise was less than that of the knuckle-upstream direction of the pantograph, and the average sound pressure level(SPL) was 3.4 dBA. The directivity of the noise radiated exhibited a typical dipole pattern in which the noise directivity was obvious at the horizontal plane of θ=0°,the longitudinal plane of θ=120°,and the vertical plane of θ=90°.

关键词： high-speed train pantograph aerodynamic noise large eddy simulation FW-H acoustic analogy boundary element method noise contribution

Numerical Simulation of the Aeroacoustic Performance of the DSA380 High-Speed Pantograph Under the Influence of a Crosswind

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Fluid Dynamics & Materials Processing 2020年第1期16卷 105-120页

作者： yadong zhang Jiye zhang Department of Mechanics and Aerospace Engineering Southern University of Science and TechnologyShenzhen518055China State Key Laboratory of Traction Power Southwest Jiaotong UniversityChengdu610031China

The object of research of this paper is the DSA380 high-speed *** near-field unsteady flow around the pantograph was investigated using large eddy simulation(LES)while the far-field aerodynamic noise was analysed in the frame of the Ffowcs Williams-Hawkings(FW-H)acoustic *** to the results,the contact strip,base frame and knuckle are the main aerodynamic noise sources,with vortex shedding,flow separation and recombination around the pantograph being related key physical *** aerodynamic noise radiates outwards in the form of spherical waves when the distance of the noise receiving point is farther than 8 *** sound pressure level(SPL)grows approximately as the 6th power of pantograph operating *** aerodynamic noise energy is mainly concentrated in the region of 400-1000 Hz,and the frequency band is wider with crosswind than without *** peak frequency displays a linear relationships with the operating speed and crosswind velocity,*** aerodynamic and aeroacoustic generation from the knuckle-downstream orientation of the pantograph is superior to those of the knuckle-upstream orientation *** finding may be used for the optimal design of future pantograph configurations in the presence of crosswind.

关键词： Pantograph crosswind aeroacoustic performance large eddy simulation FW-H acoustic analogy

Investigation on specific heat capacity and thermal behavior of sodium hydroxyethyl sulfonate

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Chinese Journal of Chemical Engineering 2017年第3期25卷 319-323页

作者： Hongying Hao yadong zhang Xiaoya Chen School of Chemical Engineering and Energy Zhengzhou University Medical School HuangHe Science and Technology College

The thermal decomposition process was studied by the TG–DTA analyzer. The results show that the decomposition process of sodium hydroxyethyl sulfonate consisted of three stages: the mass loss for the first, the second and third stages may be about the groups of CH_3CH_2OH, CH_3CHO and SO_2 volatilized, respectively. The decomposition residuum of three stages was analyzed by FT-IR, and the results of FT-IR agreed with the decomposition process predicted by theoretical weight loss. The specific heat capacity of sodium hydroxyethyl sulfonate was determined by differential scanning calorimetry(DSC). The melting temperature and melting enthalpy were obtained to be 465.41 K and 25.69 kJ·mol^(-1), respectively. The molar specific heat capacity of sodium hydroxyethyl sulfonate was determinated from 310.15 K to 365.15 K and expressed as a function of temperature.

关键词： Sodium hydroxyethyl sulfonate Melting temperature Specific heat capacity Thermal decomposition

Porous silica nano-flowers stabilized Pt-Pd bimetallic nanoparticles as heterogeneous catalyst for efficiently synthesizing guaiacol from 2-methoxycyclohexanol

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Chinese Journal of Chemical Engineering 2024年第6期70卷 222-233页

作者： Junbo Feng Junyan Wu Dongdong Yan yadong zhang School of Chemical Engineering Zhengzhou UniversityZhengzhou 450001China State Key Laboratory of Coking Coal Exploitation and Comprehensive Utilization Pingdingshan 467000China Jiyuan Research Institute Zhengzhou UniversityJiyuan 459000China School of Materials and Chemical Engineering Zhongyuan University of TechnologyZhengzhou 450007China

Porous silica nano-flowers(KCC-1)immobilized Pt-Pd alloy NPs(Pt-Pd/KCC-1)with different mass ratios of Pd and Pt were successfully prepared by a facile in situ one-step reduction,using hydrazinium hydroxide as a reducing *** as-synthesized silica nanospheres possess radial fibers with a distance of 15 nm,exhibiting a high specific surface area(443.56 m^(2)·g^(-1)).Meanwhile,the obtained Pt-Pd alloy NPs are uniformly dispersed on the silica surface with a metallic particle size of 4-6 nm,which exist as metallic Pd and Pt on the surface of monodisperse KCC-1,showing the transfer of electrons from Pd to *** as-synthesized 2.5%Pt-2.5%Pd/KCC-1 exhibited excellent catalytic activity and stability for the continuous dehydrogenation of 2-methoxycyclohexanol to prepare *** with Pt or Pd single metal supported catalysts,the obtained 2.5%Pt-2.5%Pd/KCC-1 shows 97.2%conversion rate of 2-methoxycyclohexanol and 76.8%selectivity for guaiacol,which attributed to the significant synergistic effect of bimetallic Pt-Pd alloy ***,turn over frequency value of the obtained 2.5%Pt-2.5%Pd/KCC-1 NPs achieved 4.36 s^(-1),showing higher catalytic efficiency than other two monometallic *** pathways of dehydro-aromatization of 2-methoxycyclohexanol over the obtained catalyst are ***,the obtained 2.5%Pt-2.5%Pd/KCC-1 NPs prove their potential in the dehydrogenation of 2-methoxycyclohexanol,while the kinetics and mechanistic study of the dehydrogenation reaction over the catalyst in a continuous fixed-bed reactor may provide valuable information for the development of green,outstanding and powerful synthetic pathway of guaiacol.

关键词： Supported catalyst Nanoparticles Dehydrogenation 2-Methoxycyclohexanol Guaiacol

Finite Spherical Cavity Expansion Method for Layering Effect

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Acta Mechanica Solida Sinica 2016年第6期29卷 642-654页

作者： Xiangzhen Kong Qin Fang Hao Wu yadong zhang State Key Laboratory for Disaster Prevention & Mitigation of Explosion & Impact PLA University of Science & Technology

A decay function for the layering effect during the projectile penetrating into layered targets is constructed, which is obtained via the theoretical solution of a dynamically expanding layered spherical cavity with finite radius in the layered targets that are assumed to be incom- pressible Mohr-Coulomb materials. By multiplying the decay function with the semi-empirical forcing functions that account for all the constitutive behavior of the targets, the forcing functions for the layered targets are obtained. Then, the forcing functions are used to represent the targets and are applied on the projectile surface as the pressure boundary condition where the projectile is modeled by an explicit transient dynamic finite element code. This methodology is implemented into ABAQUS explicit solver via the user subroutine VDLOAD, which eliminates the need for discretizing the targets and the need for the complex contact algorithm. In order to verify the proposed layering effect model, depth-of-penetration experiments of the 37 mm hard core pro-jectile penetrating into three sets of fiber concrete and soil layered targets are conducted. The predicted depths of penetration show good agreement with the experimental data. Furthermore, the influence of layering effect on projectile trajectory during earth penetration is investigated. It is found that the layering effect should be taken into account if the final position and trajectory of the projectile are the main concern.

关键词： finite spherical cavity expansion layering effect depth of penetration projectiletrajectory

Experimental and theoretical study on N-hydroxyphthalimide and its derivatives catalyzed aerobic oxidation of cyclohexylbenzene

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Chinese Journal of Chemical Engineering 2022年第4期35卷 124-130页

作者： Yufei Yang Jieyi Ma Junyan Wu Weixia Zhu yadong zhang School of Chemical Engineering Zhengzhou UniversityZhengzhou 450001China Jiyuan Research Institute Zhengzhou UniversityJiyuan 459000China

The liquid phase oxidation of cyclohexylbenzene(CHB)is a new green synthetic approach to cyclohexylbenzene-1-hydroperoxide(CHBHP),a key intermediate for preparing phenol and *** this work,aryl-substituted(Cl and Br)derivatives of N-hydroxyphthalimide(NHPI)were synthesized and their catalytic performances for CHB oxidation were *** addition,geometric optimization and transition state search were performed using DFT *** experimental and theoretical studies have proven that chloro-substitution on NHPI can significantly improve its catalytic effects on the oxidation of CHB by *** with NHPI,CHB conversion and selectivity of CHBHP over Cl;NHPI were increased by 10.47%and 13.24%.The strategy of aryl-substituting NHPI with halogen atoms proposed in this study would provide a potential way to the development of new NHPI-based catalysts for aerobic oxidation reactions.

关键词： N-hydroxyphthalimide Aryl-substituted derivative Cyclohexylbenzene Oxidation Radical

Growth and Characteristics of n-VO2/p-GaN based Heterojunctions

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Journal of Wuhan University of Technology(Materials Science) 2020年第2期35卷 342-347页

作者： zhang yadong zhang Bingye WANG Minhuan FENG Yulin BIAN Jiming Key Laboratory of Materials Modification by Laser Ion and Electron Beams(Ministry of Education)School of PhysicsDalian University of TechnologyDalian 116024China

n-VO2/p-GaN based oxide-nitride heterojunctions were realized by growing high quality VO2 films with precisely controlled thickness on p-GaN/sapphire substrates by oxide molecular beam epitaxy(O-MBE).The high crystalline quality of the n-VO2/p-GaN heterojunctions were confirmed by X-ray diffraction(XRD)and scanning electron microscope(SEM)*** phase transition characteristics of the as-grown n-VO2/p-GaN heterojunctions were systematically investigated by temperature-dependent resistivity and infrared transmittance *** results indicated that an excellent reversible metal-to-insulator(MIT)transition is observed with an abrupt change in both resistivity and infrared transmittance(IR)at 330 K,which was lower than the 341 K for bulk single crystal ***,the resistivity-temperature curve was well consistent with that obtained from the temperature dependent IR ***,the current-voltage characteristics originated from the n-VO2/p-GaN interface were demonstrated both before and after MIT of VO2 overlayer,which were attributed to the p-n junction behavior and Schottky contact character,*** design and modulation of the n-VO2/p-GaN based heterostructure devices will benefit significantly from these achievements.

关键词： vanadium oxide molecular beam epitaxy oxide-nitride heterojunctions metal-insulator transition

Conditional privacy protection authentication scheme based on bilinear pairings for VANET

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The Journal of China Universities of Posts and Telecommunications 2020年第1期27卷 62-71页

作者： Song Cheng Gu Xin'an Ping Yuan zhang yadong School of Computer Science and Technology Henan Polytechnic UniversityJiaozuo 454000China School of Information Engineering Xuchang UniversityXuchang 461000China

To solve the problem of security and efficiency of anonymous authentication in the vehicle Ad-hoc network(VANET), a conditional privacy protection authentication scheme for vehicular networks is proposed based on bilinear pairings. In this scheme, the tamper-proof device in the roadside unit(RSU) is used to complete the message signature and authentication process together with the vehicle, which makes it more secure to communicate between RSU and trusted authority(TA) and faster to update system parameters and revoke the vehicle. And this is also cheaper than installing tamper-proof devices in each vehicle unit. Moreover, the scheme provide provable security proof under random oracle model(ROM), which shows that the proposed scheme can meet the security requirements such as conditional privacy, unforgeability, traceability, etc. And the results of simulation experiment demonstrate that this scheme not only of achieves high efficiency, but also has low message loss rate.

关键词： VANET anonymous authentication bilinear pairings conditional privacy protection

THE　VALUE　OF　COMPOSITION　GAMES　AND(0,1)　NORMALIZATION　GAMES(Ⅰ—Ⅱ)

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Applied Mathematics(A Journal of Chinese Universities) 1997年第2期12卷 205-214页

作者： zhang SHENGKAI, YAN HUIZHEN AND zhang yadong Dalian Institute of Light Industrial Technology Dalian

Abstract In this paper we have studied n person game problems of (0,1) normalization and composition. Also we have concerned multilinear extensions of composition games and especial games [5—7,9—14]. As we have... 详细信息

关键词： Composition Multilinear extension Normalization game Shapley value