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Influencing factors on elastic-plastic deformation of multi-layered surfaces under sliding contact

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中国有色金属学会会刊：英文版 2004年第z1期14卷 472-477页

作者： YAN Li PAN Xin-xiang XU Jiu-jun CHENG Dong Institute of Materials and Technology Dalian Maritime University China Institute of Materials and Technology Dalian Maritime University China Institute of Materials and Technology Dalian Maritime University China Institute of Materials and Technology Dalian Maritime University China

Stress distribution in the gradient multi-layered surface under a sliding contact was investigated using finite element method(FEM). The main structure parameters of layered surface discussed are total layer thickness,layer number and elastic modulus ratio of layer to the substrate. A model of multi-layered surface contact with rough slider was studied. The effect of the surface structure parameters on the elastic-plastic deformation was analyzed.

关键词： gradient multi-layered surface elastic-plastic deformation surface structure parameter FEM

Effect of ro-vibrational excitation of NeH^+ on the stereodynamics for the reactions H+NeH^+(v=1-3,j=1,3,5) →H_2^++Ne

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Chinese Physics B 2013年第2期22卷 524-530页

作者：尹淑慧邹静涵郭明星李磊许雪松高宏车丽 Department of Physics Dalian Maritime University Environmental Science and Engineering College Dalian Maritime University

The stereodynamics of the abstraction reaction H^＋ NeH^＋（v = 1-3,j = 1,3,5） → H2^＋＋ Ne is studied theoretically with a quasi-classical trajectory method on a new ab initio potential energy surface [ S J,Zhang P Y,Han K L and He G Z 2012 ***.132 014303].The effects of vibrational and rotational excitation of reagent molecules on the polarization of the product are *** reaction cross sections,the distributions of P（θr）,P（φr）,and polarizationdependent differential cross sections（PDDCSs） are *** obtained cross sections indicate that the title reaction is a typical barrierless atom（ion）-ion（molecule） *** initial vibrational excitation and rotational excitation of reagent molecules have distinctly different influences on stereodynamics of the title reaction,and the possible reasons for the differences are presented.

关键词： stereodynamics quasi-classical trajectory polarization vibrational excitation rotational excitation

Predictor-based neural dynamic surface control for distributed formation tracking of multiple marine surface vehicles with improved transient performance

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Science China(Information Sciences) 2016年第9期59卷 208-226页

作者： Zhouhua PENG Dan WANG Tieshan LI School of Marine Engineering Dalian Maritime University Control Science and Engineering Dalian University of Technology School of Navigation Dalian Maritime University

In this paper, we investigate the distributed formation tracking problem of multiple marine surface vehicles with model uncertainty and time-varying ocean disturbances induced by wind, waves, and ocean currents. The objective is to achieve a collective tracking with a time-varying trajectory, which can only be accessed by a fraction of follower vehicles. A novel predictor-based neural dynamic surface control design approach is proposed to develop the distributed adaptive formation controllers. We use prediction errors, rather than tracking errors, to construct the neural adaptive laws, which enable the fast identification of the vehicle dynamics without incurring high-frequency oscillations in control signals. We establish the stability properties of the closed-loop network via Lyapunov analysis, and quantify the transient performance by deriving the truncated L2 norms of the derivatives of neural weights, which we demonstrate to be smaller than the classical neural dynamic surface control design approach. We also extend the above result to the distributed formation tracking using the relative position information of vehicles, and the advantage is that the velocity information of neighbors and leader are required. Finally, we give the comparative studies to illustrate the performance improvement of the proposed method.

关键词： dynamic surface control distributed formation tracking predictor marine surface vehicles neural networks

Study on the influences of ionization region material arrangement on Hall thruster channel discharge characteristics

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Plasma Science and Technology 2018年第2期20卷 47-55页

作者：胡翔段萍宋继磊李文庆陈龙边兴宇 College of Science Dalian Maritime University Transportation Engineering Postdoctoral Research Station Dalian Maritime University

There exists strong interaction between the plasma and channel wall in the Hall thruster,which greatly affects the discharge performance of the *** this paper,a two-dimensional physical model is established based on the actual size of an Aton P70 Hall thruster discharge *** particle-in-cell simulation method is applied to study the influences of segmented low emissive graphite electrode biased with anode voltage on the discharge characteristics of the Hall thruster *** influences of segmented electrode placed at the ionization region on electric potential,ion number density,electron temperature,ionization rate,discharge current and specific impulse are *** results show that,when segmented electrode is placed at the ionization region,the axial length of the acceleration region is shortened,the equipotential lines tend to be vertical with wall at the acceleration region,thus radial velocity of ions is reduced along with the wall *** axial position of the maximal electron temperature moves towards the exit with the expansion of ionization ***,the electron-wall collision frequency and ionization rate also increase,the discharge current decreases and the specific impulse of the Hall thruster is slightly enhanced.

关键词： Hall thruster segmented electrode particle-in-cell wall material

Solid-state synthesis and electrochemical properties of SmVO_4 cathode materials for low temperature SOFCs

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Rare Metals 2006年第z1期25卷 240-242页

作者： SUN Xueli LI Song SUN Juncai Institute of Materials and Technology Dalian Maritime University Dalian 116026 China Institute of Materials and Technology Dalian Maritime University Dalian 116026 China Institute of Materials and Technology Dalian Maritime University Dalian 116026 China

A new cathode material fabricated by solid state reaction method was reported. The SmVO4 powder was obtained by firing the mixture of Sm2O3 and V2O5 powders in the temperature range of 700-1200 ℃. Its structure was identified by X-ray diffraction method and the electrochemical properties of SmVO4 as cathodes for solid oxide fuel cells (SOFCs) were investigated in single unit cell at the temperature ranged from 450-550 ℃. The results of the single fuel cell unit show that the maximum current densities are 641, 797, 688 mA·cm-2 and the maximum power output are 165, 268, 303 mW·cm-2 and the open circuit voltage are 1.04, 0.96, 0.92 V at 450, 500 and 550 ℃, respectively.

关键词： SOFC SmVO4 cathode solid-state reaction electrochemical properties

Remarkable fluorescence enhancement of upconversion composite film and its application on mercury sensing

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Journal of Rare Earths 2017年第5期35卷 460-467页

作者：徐赛张艳秋李香萍张金苏孙佳石程丽红陈宝玖 Department of Physics Dalian Maritime University Dalian 116026 China Transportation Equipment & Ocean Engineering College Dalian Maritime University Dalian 116026 China

To achieve a stable, sensitive, and high-efficiency biological probe, a novel NaYF4：Yb,Er nanocrystals/TiO2 inverse opal composite film was designed by self-assembly and solvent evaporation methods. 32-fold enhanced upconversion（UC） emission was investigated under 980 nm excitation. According to size-dependency, excitation power density-dependency as well as photonic stop band（PSB）-dependency upconversion spectra, the enhancement mechanism of the composite film was put down to the stochastical diffraction of IOPCs multi-layered structure to the excitation laser. On the basis of the enhancement effect of the composite film, energy transfer between upconversion nanoparticles（UCNPs） and quantum dots（QDs）, and the sensitive sensing of CdTe QDs on mercury, the UC composite film was used for sensing of Hg^2＋ in serum. The solid sensor as a mercury detector owns lots of superiorities such as feasible operation, good linear relationship（R=0.997）, low limit of detection（70.5 nmol/L） and thus may have broad prospects in the biosensing field.

关键词： mercury excitation dependency layered assembly evaporation CdTe inverse luminescence photonic

DIFFERENTIAL SCANNING CALORIMETRY AND X-RAY DIFFRACTION STUDIES ON AGING BEHAVIOR OF Zn-Al ALLOYS

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Acta Metallurgica Sinica(English Letters) 2001年第2期14卷 109-114页

作者： X.L. Xu, Z. W. Yu, S.J. Ji, J.C. Sun and Z.K. Hei (dalian maritime university, dalian 116024, China) dalian maritime university

Decomposition processes of the quenched Zn-Al alloys were studied by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the stabilities of supersaturated solid solution (SSS) of Zn-Al alloy and α' phase formed by quenching would reduce with the increase of Zn content and the precipitation of η-Zn phases even when aging at ambient temperature, so that the exothermic precipitation peak in DSC curve would disappear. The activation energy of the η-Zn precipitation and the reaction enthalpy were calculated and measured. The kinetics of α' decomposition or η-Zn formation was determined by XRD. The microstructure change during aging was observed by TEM.

关键词： Aging of materials Aluminum alloys Differential scanning calorimetry X ray diffraction

A precise tidal prediction mechanism based on the combination of harmonic analysis and adaptive network-based fuzzy inference system model

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Acta Oceanologica Sinica 2017年第11期36卷 94-105页

作者： ZHANG Zeguo YIN Jianchuan WANG Nini HU Jiangqiang WANG Ning Navigation College Dalian Maritime University Dalian 116026 China Department of Mathematics Dalian Maritime University Dalian 116026 China Marine Engineering College Dalian Maritime University Dalian 116026 China

An efficient and accurate prediction of a precise tidal level in estuaries and coastal areas is indispensable for the management and decision-making of human activity in the field wok of marine engineering. The variation of the tidal level is a time-varying process. The time-varying factors including interference from the external environment that cause the change of tides are fairly complicated. Furthermore, tidal variations are affected not only by periodic movement of celestial bodies but also by time-varying interference from the external environment. Consequently, for the efficient and precise tidal level prediction, a neuro-fuzzy hybrid technology based on the combination of harmonic analysis and adaptive network-based fuzzy inference system（ANFIS）model is utilized to construct a precise tidal level prediction system, which takes both advantages of the harmonic analysis method and the ANFIS network. The proposed prediction model is composed of two modules： the astronomical tide module caused by celestial bodies’ movement and the non-astronomical tide module caused by various meteorological and other environmental factors. To generate a fuzzy inference system（FIS） structure,three approaches which include grid partition（GP）, fuzzy c-means（FCM） and sub-clustering（SC） are used in the ANFIS network constructing process. Furthermore, to obtain the optimal ANFIS based prediction model, large numbers of simulation experiments are implemented for each FIS generating approach. In this tidal prediction study, the optimal ANFIS model is used to predict the non-astronomical tide module, while the conventional harmonic analysis model is used to predict the astronomical tide module. The final prediction result is performed by combining the estimation outputs of the harmonious analysis model and the optimal ANFIS model. To demonstrate the applicability and capability of the proposed novel prediction model, measured tidal level samples of Fort Pulaski tidal station are selecte

关键词： tidal level prediction harmonious analysis method adaptive network-based fuzzy inference system correlation analysis

Performance Analysis of Inter-Stage Leakage Flows at Rotating Conditions in an Axial Compressor

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Journal of Thermal Science 2020年第6期29卷 1558-1568页

作者： KONG Xiaozhi LIU Yuxin LU Huawei TIAN Zhitao XIN Jianchi Naval Architecture and Ocean Engineering College Dalian Maritime UniversityDalian 116026China Marine Engineering College Dalian Maritime UniversityDalian 116026China

For the compressor with shrouded stator blades,the stator well is a rotor-stator space between the rotating drum and the stationary *** to the pressure difference,a reverse leakage flow would travel through the stator well and inject into the main flow ***,the labyrinth seal is commonly placed under the shroud,the rotation effect and seal clearance variation in actual operation process have great impact on the characteristics of this inter-stage leakage,as well as the compressor *** this paper,experiments were conducted at a compressor inter-stage seal test *** leakage flow rates,total temperatures and swirl ratios were obtained at different speeds and working *** proportions of rotation effect and the clearance reduction effect were analyzed by data *** indicate that the working clearance and leakage flow reduce about 43%and 50%respectively,when the rotational speedω=8100 r/*** proportion of reduction caused by the rotation effect is around 15%,while the influence of working clearance variation is much greater,accounting for about 35%.The windage heating coefficient and swirl ratio in the outlet cavity are almost in exponential relationship with the rotor *** increases in total temperature and swirl ratio generated by the rotation effect are found to be about 80%.In addition,the swirl and radial velocity profiles in the cavities were discussed by validated numerical simulations to reveal the typical flow *** data presented can provide guidance for better leakage conditions prediction as well as the inter-stage seal design enhancement.

关键词： shrouded stator blade inter-stage seal rotor-stator cavity leakage flow windage heating swirl ratio