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Coercivity Enhancement of Nd-Fe-B Thin Film Magnets through Dy Surface Diffusion Process

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Journal of Materials Science & Technology 2011年第9期27卷 826-830页

作者： C.Y. You J. zhu N. Tian z.X. Lu State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China School of Materials Science and Engineering Xi＇an University of Technology Xi＇an 710048 China

The Dy capping layer was deposited at different temperatures on the Nd-Fe-B thin films to investigate the mechanism of the coercivity enhancement through the Dy surface diffusion. The highest coercivity of 2005 kA/m （25.2 kOe） was obtained at the Dy deposition temperature of 460℃, which was significantly higher than the value of 1297 kA/m （16.3 kOe） without Dy capping layer. By performing the transmission electron microscopy （TEM） analysis, it was found that some of the grain boundaries were enriched with Nd element, which could be partly ascribed to the promotion by the Dy surface diffusion. In comparison to the evolution of the spin reorientation temperature of Nd2Fe14B phase after the deposition of the Dy capping layer, it is concluded that structural modification plays a significant role in the coercivity enhancement due to the Dy surface diffusion.

关键词： Nd-Fe-B thin film Coercivity enhancement Dy layer Microstructure

Hybrid Excited Permanent Magnet Machines for Electric and Hybrid Electric Vehicles

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CES Transactions on Electrical Machines and Systems 2019年第3期3卷 233-247页

作者： z.Q.zhu S.Cai Department of Electronics and Electrical Engineering University of SheffieldSheffieldS13JD U.K

This paper reviews various hybrid excited(HE)machines from the perspective of location of PM and DC excitation,series/parallel connection of PM and DC excited magnetic fields,and 2D/3D magnetic fields,*** advantages as well as drawbacks of each category are *** an additional control degree,*** excitation,is introduced in the HE machine,the flux weakening control strategies are more *** flux weakening performance as well as efficiency are compared with different control ***,the potential to mitigate the risk of uncontrolled overvoltage fault at high speed operation is highlighted by controlling the field *** additional DC coils are usually required for HE machines compared with pure PM excitation,the spatial confliction inevitably results in electromagnetic performance ***,the technique to integrate the field and armature windings with open-winding drive circuit is introduced,and novel HE machines without a DC coil are summarized.

关键词： Electric vehicle(EV) flux weakening control hybrid electric vehicle(HEV) hybrid excited(HE)machine open-winding permanent magnet(PM).

Investigation on Fatigue Model of Asphalt Concrete Containing Conductive Fillers

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武汉理工大学学报 2010年第17期32卷 62-66页

作者： LI W T WU S P zhu z H LIU z F Key Laboratory of Silicate Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China

The snow and ice on asphalt pavement are very dangerous to people,automobiles and airplanes,so melting snow and ice becomes a high profile. Investigation on the asphalt concrete containing conductive fillers has a great contribution to the researches of melting snow and ice. However,it is few to research on the fatigue behavior which is important in the profile. By four-point bending fatigue tests,the specific fatigue models of conductive asphalt concrete were developed. The parameters of three fatigue models were regressed,the three models predicted the fatigue behavior by the strain levels,the strain levels and initial mix stiffness and dissipated energy respectively. In the model of the strain levels,the fatigue life is decreased at the same strain level as the conductive filler is added. The model based on the strain levels and initial mix stiffness reveals that the fatigue life is partly affected by the initial mix stiffness which is influenced by the conductive filler. The model used the dissipated energy approach is adopted to predict the fatigue behavior with the introduction of the impact the conductive filler on the dissipated energy.

关键词： conductive asphalt concrete model fatigue life strain level stiffness dissipated energy

Optimal Split Ratio in Small High Speed PM Machines Considering Both Stator and Rotor Loss Limitations

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CES Transactions on Electrical Machines and Systems 2019年第1期3卷 3-11页

作者： J.Ma z.Q.zhu Department of Electrical and Electronic Engineering The University of SheffieldSheffieldS13JDU.K.

The split ratio which is defined as the ratio between rotor and stator outer diameters is critical for permanent magnet(PM)*** this paper,the split ratio in small high speed PM machines is optimized analytically by considering both stator and rotor loss *** this way,the thermal constrains in both stator and rotor parts can be taken into *** shows that both losses can significantly affect the optimal split ratio and the machine *** considering the influence of rotor losses,especially the rotor eddy current loss,the optimal split ratio is increased significantly in certain *** output torque is calculated analytically and the influences of several key design parameters on the optimal split ratio,***/pole combinations and magnet materials,are also investigated in ***,finite element(FE)analyses are carried out for validating of the analytical model.

关键词： Index Terms-High speed permanent magnet split ratio.

Influence of Rotor Iron Bridge Position on DC-winding-induced Voltage in Wound Field Switched Flux Machine Having Partitioned Stators

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Chinese Journal of Electrical Engineering 2021年第3期7卷 20-28页

作者： zhongze Wu z.Q.zhu Chao Wang Wei Hua Kai Wang Wentao zhang School of Electrical Engineering Southeast UniversityNanjing 210096China Department of Electronic and Electrical Engineering University of SheffieldSheffield S102TNUK College of Automation Nanjing University of Aeronautics and AstronauticsNanjing 211106China

In this study,the influence of the position of the rotor iron bridge on the DC-winding-induced voltage pulsation in a partitioned stator wound field switched flux machine is *** and finite element(FE)analyses show that both the open-circuit and on-load DC-winding-induced voltages can be minimized by positioning the rotor iron bridge adjacent to the inner air gap closer to the DC *** is due to a smoother inner air-gap magnetic reluctance while maintaining the average electromagnetic torque at 92.59%of the maximum *** analyzed machine with the rotor iron bridge adjacent to the inner air gap is prototyped,and the experimental results validate the analytical and FE results.

关键词： DC winding induced voltage flux switching iron bridge partitioned stator switched flux wound field

First-principles Calculation Assisted Thermodynamic Modeling of Ti-Co-Cu Ternary System

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Journal of Materials Science & Technology 2010年第4期26卷 317-326页

作者： Y.J. Yang X.M. Tao W.J. zhu z.H. Long H.S. Liu z.P. Jin School of Materials Science and Engineering Central South University Changsha 410083 China Key Lab of Non-ferrous Metal Science and Engineering Ministry of Education Changsha 410081 China

Thermodynamic assessment of Ti-Co-Cu ternary system has been carried out by combining first-principle calculation and CALPHAD method. Firstly, formation enthalpies of stable and hypothesized compounds were calculated by first-principles method. Then, based on reported experimental information, a thermodynamic description of the Ti-Co-Cu ternary system was performed. Solution phases were treated as substitutional solutions of which excess Gibbs energies were formulated by Redlich-Kister polynomial, and the intermediate phases were described with sublattice models. All measured isothermal sections were reasonably reproduced. In addition, liquidus projection of this ternary system was further calculated, which may be useful for relevant materials processing.

关键词： First-principle CALPHAD Thermodynamic modeling

The Surface Coatings Industry of China

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涂料工业 1993年第1期 34-38页

作者： z.N.Yu,Y.S.zhu

It had ever sinee been several thousand yearsthat the art of emPloying natural laequers anddrying ofis for Protection and decoration waswidely Praetised in Qljna,a land of aneient eivi-lization. Ninetee

关键词： ting Co Pr The Surface Coatings Industry of China

Influence of Inner/Outer Stator Pole Ratio and Relative Position on Electromagnetic Performance of Partitioned Stator Switched Flux Permanent Magnet Machines

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CES Transactions on Electrical Machines and Systems 2019年第3期3卷 259-268页

作者： J.T.Shi z.Q.zhu Department of Electronic and Electrical Engineering The University of Sheffield3 Solly StreetSheffieldS14DEUK

Based on the 6-pole outer stator(armature winding-stator),the influence of inner(permanent magnet-stator)/outer stator pole ratio n(n=NIS/NOS),stator relative positions and rotor pole number combinations on electromagnetic performance of partitioned stator switched flux permanent magnet(PM)machines(PS-SFPMMs)is investigated in this *** the armature windings and PMs are located in two separated stators and PMs are stationary,PS-SFPMMs have high fault tolerance *** maximize the torque performance,the PM of inner stator pole should be aligned with outer stator pole when n is odd while the iron rib of inner stator pole should be aligned with outer stator pole when n is *** matter what n is selected,the rotor pole number NR can be any integers except the phase number and its *** analysis results indicate that the optimal NR is closed to(NIS+NOS)/2 and it is odd when n is odd while it is even when n is ***,symmetrical phase back-EMF waveform will be obtained when the ratio of Min(NOS,NIS)to the greatest common divisor of Min(NOS,NIS)and NR is *** on the optimal rotor pole numbers for 6-pole outer stator with different n and corresponding optimal relative position together with same rated copper loss,the average torque is improved by 18.4%,25.1%and 25.7%respectively in PS-SFPMMs with n equal to 2,3 and 4 when compared with PS-SFPMM with n equal to *** analyses are validated by experiment results of the prototype machine.

关键词： Inner/outer stator partitioned stator permanent magnet pole ratio relative position switched flux.

Experimental study of the dissipation of supersaturated TDG during the jet breakup process

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Journal of Hydrodynamics 2019年第4期31卷 760-766页

作者： Hong-cheng Xue Qian Ma Ran Li Ming-jun Diao David z. zhu Jing-ying Lu State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan University Chengdu 610065 China Southwest Hydraulic Institute for Waterways Chongqing Jiaotong University Chongqing 400016 China Department of Civil and Environmental Engineering University of Alberta Edmonton Canada

Elevated levels of the total dissolved gas (TDG) may occur downstream the dams during the spill process to increase the incidence of the gas bubble disease for fish. With increasing numbers of cascade hydropower stations being constructed or planned, the cumulative effects of the TDG supersaturation become an increasingly prominent issue. Previous studies of the supersaturated TDG mainly focused on the generation process in the stilling basin downstream the dam while ignoring the saturation changes during the jet breakup process by assuming a 100% plunge-in-level. This assumption may lead to errors in the TDG generation predictions and the scientific assessments of the TDG supersaturation. Therefore, in this paper, physical experiments are conducted to analyze the dissipation of the supersaturated TDG in the jet breakup process, and to establish a quantitative relation between the initial TDG level and the detention time of the jet in the air. These results indicate how the supersaturated TDG generated by an upstream dam affects the TDG generation and provide a scientific support for accurate predictions of the supersaturated TDG generation for high dam spills.

关键词： Jet breakup total dissolved gas (TDG) supersaturation high dam initial saturation dissipation