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INVESTIGATION ON FRACTURE BEHAVIOR FOR WELDED JOINT OF NEW GENERATION FINE GRAINED STEEL SS400

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Acta Metallurgica Sinica(English Letters) 2003年第1期16卷 35-40页

作者： H.Y.Jing X.G.Liu z.q.zhu L.X.Huo Y.F.zhang Sch. of Mat. Sci. and Eng. Tianjin Univ. Tianjin 300072 China

The fracture behavior for welded joint of new generation fine grained steel SS400 was investigated and assessed on the basis of fitness for purpose philosophy. The actual critical defect sizes for the SS400 base metal and its weld HAz (heat affected zone) defined by the gross yielding criterium have been determined directly by means of wide plate tests. It has been shown that although the HAz grain growth occurs due to the welding heat, the resistance to fracture is not deteriorated. The deformation behavior of wide plate specimen was also studied by finite, element (FE) analysis. The deformation of weld HAz is protected by the high strength weld metal, so it is easier to get the general yielding for the welded joint specimen.

关键词： fine grained steel general yielding wide plate test fracture behavior

Six-step Voltage Control of PM Brushless AC Motors under High Speed Flux-weakening Operation for EV/HEV Applications

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电力电子技术 2008年第10期42卷 2-4,13页

作者：诸自强 Department of Electronic and Electrical Engineering University of Sheffield Mappin Street Sheffield S1 3JD UK

The torque-speed characteristics of brushless motor having an interior permanent magnet rotor and a sinusoidal back-emf waveform are compared experimentally when it is operated in brushless AC(BLAC) mode and brushless DC (BLDC) modes with both 2-phase,120° conduction(BLDC-120) and 3-phase,180° conduction(BLDC-180).Particular emphasis is on high-speed,six-step voltage controlled,flux-weakening *** is shown that for EV/HEV applications,even for interior PM brushless motors which have sinusoidal back-emf waveforms,in order to achieve maximum torque per ampere capability over wide operation speed range,it is advantageous to employ a hybrid operation mode-BLAC operation in the constant torque region and six-step voltage control(BLDC-180 operation,together with current phase control) in the flux-weakening region.

关键词：电压控制方法交流电动机频率

Compensation of Unbalanced Impedance of Asymmetric Wind Power PMSG Compensated by External Circuits in Series

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CES Transactions on Electrical Machines and Systems 2017年第2期1卷 180-188页

作者： Yashan Hu z.q.zhu Milijana Odavic Sheffield Siemens Wind Power Research Centre and Department of Electronic and Electrical Engineering University of SheffieldMappin StreetSheffield S13JDUK Royal Academy of Engineering

The unbalanced impedance of the asymmetric 3-phase wind power permanent magnet synchronous generator(PMSG)compensated by external circuits in series with the 3-phase windings is investigated in this *** asymmetric impedance includes the unbalanced resistances,unbalanced self-inductances,and unbalanced mutual *** the perspective of the second harmonic inductances in dq-frame and from the perspective of the second harmonic power,it is theoretically demonstrated that the original asymmetric 3-phase system with asymmetric impedance can be modified to a balanced system by external circuits consisting of resistances and ***,the second harmonic power and DC bus voltage due to the asymmetries can be suppressed naturally without any software *** feasibility of this compensation method is validated by elaborate experiments at different speeds and under different load condition,although the effectiveness might be slightly affected by the non-linearity of the compensation inductance in practice.

关键词： Asymmetry compensation in series second harmonic DC bus voltage unbalance compensation unbalanced impedance

Modularity Techniques in High Performance Permanent Magnet Machines and Applications

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CES Transactions on Electrical Machines and Systems 2018年第1期2卷 93-103页

作者： z.q.zhu Y.X.Li University of Sheffield UK

This paper reviews the modularity techniques in the stator manufacture of permanent magnet machines for different *** basic concepts of modular machines are firstly *** machines for several typical applications are then described in details,including domestic appliances,automobiles and electric vehicles,more electric aircrafts and civic applications,wind power generators,***,the influence of manufacture tolerance gaps and flux barriers on the electromagnetic performance is discussed.

关键词： Domestic appliance electric vehicle(EV) modular machine more electric aircraft permanent magnet wind power generator

Recent Advances in Variable Flux Memory Machines for Traction Applications: A Review

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CES Transactions on Electrical Machines and Systems 2018年第1期2卷 34-50页

作者： Hui Yang Heyun Lin z.q.zhu School of Electrical Engineering Southeast UniversityNanjingP.R.China Department of Electronic and Electrical Engineering University of SheffieldSheffieldU.K

This paper overviews the recent advances in variable flux memory machines(VFMMs)for traction applications with particular reference to newly emerged machine topologies and related control *** to the use of flux memorable low coercive force(LCF)magnets,the air-gap flux of VFMM can be flexibly varied via a magnetizing current ***,the copper loss associated with the flux weakening current and high-speed iron loss can be significantly reduced,and hence high efficiency can be achieved over a wide speed and torque/power *** merits make VFMM potentially attractive for electric vehicle(EV)*** novel VFMMs are reviewed with particular reference to their topologies,working principle,characteristics and related control *** order to tackle the drawbacks in the existing VFMMs,some new designs are introduced for performance ***,the electromagnetic characteristics of an exemplified EV-scaled switched flux memory machine and various benchmark traction machine choices,such as induction machine,synchronous reluctance machines,as well as commercially available Prius 2010 interior permanent magnet(IPM)machine are ***,the key challenges and development trends of VFMM are highlighted,respectively.

关键词： AC-magnetized DC-magnetized electrical machines electric vehicles hybrid permanent magnet(PM) memory machine variable flux

quantitative Comparison of Electromagnetic Performance of Electrical Machines for HEVs/EVs

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CES Transactions on Electrical Machines and Systems 2017年第1期1卷 37-47页

作者： z.q.zhu W.q.Chu Y.Guan Royal Academy of Engineering IEEE University of Sheffield UK

In this paper,various types of sinusoidal-fed electrical machines,*** machines(IMs),permanent magnet(PM)machines,synchronous reluctance machines,variable flux machines,wound field machines,are comprehensively reviewed in terms of basic features,merits and demerits,and compared for HEV/EV traction *** latest developments are highlighted while their electromagnetic performance are quantitatively compared based on the same specification as the Prius 2010 interior PM(IPM)machine,including the torque/power-speed characteristics,power factor,efficiency map,and drive cycle based overall *** is found that PM-assisted synchronous reluctance machines are the most promising alternatives to IPM machines with lower cost and potentially higher overall *** IMs are cheaper and have better overload capability,they exhibit lower efficiency and power *** electrical machines,such as synchronous reluctance machines,wound field machines,as well as many other newly developed machines,are currently less attractive due to lower torque density and efficiency.

关键词： Electrical machines electric vehicles hybrid electric vehicles induction machines permanent magnet machines switched reluctance machines synchronous reluctance machines variable flux machines wound field machines.

Precipitation of multi-type nano-quasicrystals in a Mg-zn-Y alloy

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Journal of Magnesium and Alloys 2024年第3期12卷 997-1008页

作者： W.z.Wang X.z.zhou L.F.zhang H.q.Ye z.q.Yang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of ScienceShenyang 110016China Ji Hua Laboratory Foshan 528251China Foshan University Foshan 528231China

Mg-6zn-1Y(at.%)ribbons with strengthening precipitates of multi-type nanoquasicrystals were prepared by melt-spinning followed by aging *** evolution of the rapidly solidified ribbons during isothermal aging was comprehensively studied using various electron microscopy *** new kinds of decagonal quasicrystals were formed in aged ribbons,in addition to precipitation of nanometer icosahedral ***-resolution observations reveal that both decagonal quasicrystals can be modeled by quasiperiodic tiling with decagonal clusters of 2.5 nm in diameter,but overlap of neighboring clusters in both decagonal quasicrystals is different from the Gummelt model observed in other quasicrystals.A shell composed of complex Laves Mg-zn domains was formed surrounding each decagonal quasicrystal precipitate upon prolonged *** addition,all kinds of nanoprecipitates exhibit excellent structure and size stability at 573 *** findings may have implications for not only fundamental studies about quasicrystals,but also microstructural manipulation of high-performance Mg alloys.

关键词： quasicrystal Mg alloys Rapid solidification Scanning-transmission electron microscopy.

Difference in Unbalanced Magnetic Force of Fractional-Slot PM Machines between Internal and External Rotor Topologie

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CES Transactions on Electrical Machines and Systems 2017年第2期1卷 154-163页

作者： L.J.Wu z.q.zhu Youtong Fang Xiaoyan Huang College of Electrical Engineering Zhejiang UniversityChina epartment of electronic and electrical engineering university of sheffieldmappin streetsheffields13jduk Royal Academy of Engineering

This paper presents a comparative investigation into unbalanced magnetic force(UMF)of asymmetric permanent magnet machines without rotor eccentricities,particularly focusing on the difference between internal-and external-rotor *** asymmetric field distribution results in radial and tangential asymmetric force *** the radial and tangential stresses are in different direction,the UMF components they produce are nearly *** UMF from asymmetric radial force wave can be additive or subtractive to that from asymmetric tangential force *** shows that for the same pole slot number combination,if the UMFs due to radial and tangential force waves are additive in internal rotor machine,they are subtractive in the external rotor counterpart,and vice *** reveals a general rule determining whether additive or cancelling:for a UMF produced by any two field harmonics,they are additive if the higher order is produced by the outer part outside the airgap,but cancelling if the higher order is produced by the inner ***,for a machine with pole number 2p=3k+1,they are additive if it is an external-rotor machine,but otherwise *** the other hand,for a machine with pole number 2p=3k-1,they are subtractive if it is an external-rotor machine,but otherwise *** the UMF due to armature reaction only,they are subtractive for external-rotor machines,but otherwise *** investigation is carried out by an analytical model and validated by finite element analysis.

关键词： Analytical model electric machines fractional-slot machines permanent magnet machines unbalanced magnetic force

Rational design of AgGaS/znS/znS quantum dots with a near-unity photoluminescence quantum yield via double shelling scheme

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Journal of Materials Science & Technology 2024年第2期169卷 235-242页

作者： H.X.Lu H.Liu z.z.Fu Y.Y.Chen H.q.Dai z.Hu W.L.zhang R.q.Guo Institute for Electric Light Sources School of Information Science and TechnologyFudan UniversityShanghai 200433China Institute of Future Lighting Academy for Engineering and TechnologyFudan UniversityShanghai 200433China Yiwu Research Institute of Fudan University YiwuZhejiang 322000China zhongshan-Fudan Joint Innovation Center Zhongshan 528437China

In this study,a two-step method was used to synthesize highly luminescent AgGaS/znS/znS quantum dots(qDs).In the first step,an inner znS shell was formed via a one-pot method,which resulted in a smaller lattice mismatch between the AgGaS core and the outer znS shell,thereby facilitating the formation of a thick outer *** the two-step shelling process,the synthesized AgGaS/znS/znS qDs showed an excellent photoluminescence quantum yield(PLqY)of 96.4%with a peak wavelength of 508 nm,repre-senting the highest PLqY reported thus far for AgGaS ***,the effect of halogen ions in zn precursors on the shelling process was *** was proposed that the capacity of halogen ions to coordinate with the qDs influenced the balance between zn cation diffusion and znS shelling ***,the znS shelling reaction was dominant when znCl_(2)was employed,while zn cation diffusion was the dominant process under the I^(−)-rich *** work provides insights into the interfacial restructuring during the znS shelling and offers a clear map for the tailored synthesis of core/shell qDs.

关键词： AgGaS quantum dots Photoluminescence Core/shell Alloyed core/shell interface