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instantaneous mixing characteristics of binary mixtures differing in density in a gas-solid fluidised bed

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Particuology 2020年第6期18卷 63-71页

作者： zhen wan.Youjun Lu Hao wan. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049ShaanxiChina

Characterisations of instantaneous mixing behaviours in fluidised beds with binary mixtures has many *** studied the instantaneous mixing characteristics of binary mixtures in a 2-D quasi gas-solid fluidised bed using a capacitance probe *** method enabled the quantitative assessment of instantaneous mixing behaviours,including mixing index,rate,and *** kinds of binary mixtures of similar size but different density were used for the transient and steady fluidisation experiments in a bubbling fluidised *** mixing curves of initially segregated binary mixtures were acquired,and the instantaneous characteristics for the entire process were *** equation was proposed to describe the mixing process and predict the mixing degree over *** comparing experiments with different working conditions,the effects of superficial gas velocity and density ratio on the mixing in the centre and at the wall of the fluidised bed were *** the stable fluidisation stage,the axial concentration profiles of the mixtures were obtained,and the mechanisms of mixing were *** showed that the mixing level increased logarithmically with time and eventually reached a relatively stable *** the superficial gas velocity and reducing the density ratio promoted mixing and reduced mixing *** superficial gas velocities tended to mix the mixtures well and quickly,regardless of the density ratio of the two components.

关键词： Binary mixtures Fluidised bed Mixing instantaneous characteristics

Particle convective heat transfer near the wall in a supercritical water fluidized bed by single particle model coupled with CFD-DEM

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Particuology 2023年第2期73卷 47-58页

作者： Tianning Zhang zhen wan.Youjun Lu State Key Laboratory of Multiphase Flow in Power Engineering(SKLMFPE) Xi'an Jiaotong UniversityXi'an710049ShaanxiChina Xi'an Electronic Engineering Research institute Xi'an710100ShaanxiChina

Supercritical water fluidized bed(SCWFB)is a promising reactor to gasify biomass or *** optimization design is closely related to wall-to-bed heat transfer,where particle convective heat transfer plays an important *** paper evaluates the particle convective heat transfer coefficient(h_(pc))at the wall in SCWFB using the single particle *** critical parameters in the single particle model which is difficult to get experimentally are obtained by the computational fluid dynamics-discrete element method(CFD-DEM).The contact statistics related to particle-to-wall heat transfer,such as contact number and contact distance,are also *** results show that particle residence time(τ),as the key parameter to evaluate h_(pc),is found to decrease with rising velocity,while increase with larger thermal boundary layer thickness.τfollows a gamma function initially adopted in the gas-solid fluidized bed,making it possible to evaluate h_(pc) in SCWFB by a simplified single particle *** theoretical predicted h_(pc) tends to increase with rising thermal gradient thickness at a lower velocity(1.5 U_(mf)),while first decreases and then increases at higher velocity(1.75 and 2 U_(mf)).h_(pc) occupies 30%-57%of the overall wall-to-bed heat transfer coefficient for a particle diameter of 0.25 *** results are helpful to predict the overall wall-to-bed heat transfer coefficient in SCWFB combined with a reasonable fluid convective heat transfer model from a theoretical perspective.

关键词： Supercritical water Fluidized bed Particle residence time Discrete element method Single particle model

An advanced higher-order theory for laminated composite plates with general lamination angles

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Acta Mechanica Sinica 2011年第5期27卷 720-729页

作者： zhen Wu Hong Zhu wan.Ji Chen Key Laboratory of Liaoning Province forComposite Structural Analysis of Aerocraft and Simulation Shenyang Aerospace University 110136 Shenyang China

This paper proposes a higher-order shear deformation theory to predict the bending response of the laminated composite and sandwich plates with general lamination *** proposed theory a priori satisfies the continuity conditions of transverse shear stresses at ***,the number of unknown variables is independent of the number of *** first derivatives of transverse displacements have been taken out from the inplane displacement fields,so that the C 0 shape functions are only required during its finite element *** to C 0 continuity requirements,the proposed model can be conveniently extended for implementation in commercial finite element *** verify the proposed theory,the fournode C 0 quadrilateral element is employed for the interpolation of all the displacement parameters defined at each nodal point on the composite *** results show that following the proposed theory,simple C 0 finite elements could accurately predict the interlaminar stresses of laminated composite and sandwich plates directly from a constitutive equation,which has caused difficulty for the other global higher order theories.

关键词： Laminated and sandwich composites Higherorder theory C 0 continuity requirement Transverse shear stress

Multiple model predictive control of perching maneuver based on guardian maps

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Chinese Journal of Aeronautics 2022年第5期35卷 347-360页

作者： Rui CAO Huiwen wan.zhen HE Yuping LU College of Automated Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Considering the strong nonlinearity of Unmanned Aerial Vehicles(UAVs)resulting from high Angle of Attack(AOA)and fast maneuvering,we present a multi-model predictive control strategy for UAV maneuvering,which has a small amount of online ***,we divide the maneuver envelope of UAV into several sub-regions on the basis of the gap metric theory.A novel algorithm is then developed to determine the ploytopic model for each *** to this,a Robust Model Predictive Control based on the idea of Comprehensive optimization(iCE-RMPC)is *** control law is designed offline and optimized online to reduce the computational ***,the iCE-RMPC method is applied to design the controllers of *** addition,to guarantee the stability of whole closed-loop system,a multi-model switching control strategy based on guardian maps is put ***,the tracking performance of proposed control strategy is demonstrated by an illustrative example.

关键词： Guardian maps Model predictive control Multi-Model switching rule Online comprehensive design Perching maneuver

The breaking of spin symmetry in the single-particle resonances in deformed nuclei

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Nuclear Science and Techniques 2024年第3期35卷 237-245页

作者： zhen-Yu zheng Shou-wan.Chen Quan Liu School of Physics and Optoelectronic Engineering Anhui UniversityHefei 230601China

The exploration of spin symmetry (SS) in nuclear physics has been instrumental in identifying atomic nucleus *** this study,we solve the Dirac equation from the relativistic mean field (RMF) in complex momentum *** investigated SS and its breaking in single-particle resonant states within deformed nuclei,with a focus on the illustrative *** was the initial discovery of a resonant spin doublet in a deformed nucleus,with the expectation of the SS approaching the continuum *** increasing single-particle energy,the splitting of the resonant spin doublets widened *** escalating splitting implies diminishing adherence to the SS,indicating a departure from the expected behavior as the energy levels *** also analyzed the width of the resonant states,showing that lower orbital angular momentum resonances possess shorter decay times and that SS is preserved within broad resonant doublets,as opposed to narrow resonant *** the radial density of the upper components for the bound-state and resonant-state doublets,it becomes evident that while SS is well-preserved in the bound states,it deteriorates in the resonant *** impact of nuclear deformation (β_(2)) on SS was examined,demonstrating that an increase in β_(2) resulted in higher energy and width splitting in the resonant spin doublets,which is attributed to increased component ***,the sensitivity of spin doublets to various potential parameters such as surface diffuseness (a),radius (R),and depth (Σ0) is discussed,emphasizing the role of these parameters in *** study provides valuable insights into the behavior of spin doublets in deformed nuclei and their interplay with the nuclear structure,thereby advancing our understanding of SS in the resonance state.

关键词： Spin symmetry Resonant states Deformed nuclei Complex-momentum representation

An Alternative Scheme for Transferring Quantum States and Preparing a Quantum Network in Cavity QED

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Communications in Theoretical Physics 2007年第6期47卷 1037-1040页

作者： YANG zhen-Biao SU wan.Jun Department of Electronic Science and Applied Physics Fuzhou University Fuzhou 350002 China

An alternative scheme is proposed to transfer quantum states and prepare a quantum network in cavity QED. it is based on the interaction of a two-mode cavity field with a three-level V-type atom. in the scheme, the atom-cavity field interaction is resonant, thus the time required to complete the quantum state transfer process is greatly shortened, which is very important in view of decoherence. Moreover, the present scheme does not require one mode of the cavities to be initially prepared in one-photon state, thus it is more experimentally feasible than the previous ones.

关键词： quantum states transfer quantum network cavity QED

Charge Rate-Dependent Decomposition Mechanism of Toroidal Li_(2)O_(2)in Li-O_(2)Batteries

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Chinese Journal of Chemistry 2021年第10期39卷 2668-2672页

作者： zhen-zhen Shen Chi Zhou Rui Wen Li-Jun wan CAS Key Laboratory of Molecular Nanostructure and Nanotechnology CAS Research/Education Center for Excellence in Molecular SciencesBeijing National Laboratory for Molecular Science(BNLMS)Institute of ChemistryChinese Academy of SciencesBeijing100190 China University of Chinese Academy of Sciences Beijing100049 China

Main observation and conclusion Using in situ atomic force microscopy,we visualized the oxidation dynamic process of toroidal lithium peroxide(Li_(2)O_(2))in a working Li-O2 battery and clarified the correlation between the decomposition behavior and the charging *** was found that at a low charge rate,the decomposition could occur at the Li_(2)O_(2)/electrolyte interface,providing strong evidence that a tiny current is allowed to pass through the bulk phase of toroidal Li_(2)O_(2).Further,the evolution of the periphery thickness,diameter and center thickness of the toroid as a function of charge capacity was quantitatively *** the early stage of charging,the diameter of the toroid radially shrinks and the shrinking rate slows down in the later ***,the periphery thickness of the toroid decreases at a faster and uniform rate,while the center thickness decreases obviously in the later stage of *** the charging rate promotes the decomposition occurring at the Li_(2)O_(2)/electrode interface,causing direct desorption of the Li_(2)O_(2)from the electrode and irreversible capacity degradation.

关键词： Li-0_(2)Batteries Scanning probe microscopy Toroidal Li_(2)0_(2) Oxidation Structure-activity relationships

Microstructure Evolution and Strain-Dependent Constitutive Modeling to Predict the Flow Behavior of 20Cr–24Ni–6Mo Super-Austenitic Stainless Steel During Hot Deformation

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Acta Metallurgica Sinica(English Letters) 2018年第4期31卷 401-414页

作者： Yan-Sen Hao wan.Chun Liu zhen-Yu Liu State Key Laboratory of Rolling and Automation Northeastern University

Hot compression tests were carried out with specimens of 20Cr-24Ni-6Mo super-austenitic stainless steel at strain rate from 0.01 to 10 s^-1 in the temperature range from 950 to 1150 ℃,and flow behavior was *** analysis indicated that dynamic recrystallization（DRX）behavior was more sensitive to the temperature than strain rate,and full DRX was obtained when the specimen deformed at 1150℃.When the temperature reduced to 1050 ℃,full DRX was completed at the highest strain rate 10 s-l rather than at the lowest strain rate 0.01 s-1 because the adiabatic heating was pronounced at higher strain *** addition,flow behavior reflected in flow curves was inconsistent with the actual microstructural evolution during hot deformation,especially at higher strain rates and lower ***,flow curves were revised in consideration of the effects of adiabatic heating and friction during hot *** results showed that adiabatic heating became greater with the increase of strain level,strain rate and the decrease of temperature,while the frictional effect cannot be neglected at high strain ***,based on the revised flow curves,strain-dependent constitutive modeling was developed and verified by comparing the predicted data with the experimental data and the modified *** result suggested that the developed constitutive modeling can more adequately predict the flow behavior reflected by corrected flow curves than that reflected by experimental flow curves,even though some difference existed at 950℃ and 0.01 s^-*** main reason was that plenty of precipitates generated at this deformation condition and affected the DRX behavior and deformation behavior,eventually resulted in dramatic increase of deformation resistance.

关键词： Super-austenitic stainless steel Hot compression Adiabatic heating Constitutive modeling Microstructure evolution

Primary instabilities and bicriticality in fiber suspensions between rotating cylinders

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第9期8卷 1435-1442页

作者： wan.Zhan-hong SUN Zhi-lin YOU zhen-jiang Department of Hydrauhc and Ocean Engineering Zhejiang University. Hangzhou 310028 China School of informatics and Engineering Flinders University of South Australia Adelaide SA 5001 Australia

The linear stability of fiber suspensions between two concentric cylinders rotating independently is studied. The modified stability equation is obtained based on the fiber orientation model and Hinch-Leal closure approximation. The primary instabilities and bicritical curves have been calculated numerically. The critical Reynolds number,wavenumber and wave speeds of fiber suspensions as functions of the aspect ratio,volume concentration of the fibers and the gap width of cylinders are obtained.

关键词： Fiber suspensions Primary instability Non-axisymmetric disturbances