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Nuclear Science and Techniques 2023年第2期34卷 128-138页

作者： Xing‑Chao Shen yuan fu Jian‑yu Zhang Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China University of Chinese Academy of Sciences Beijing 100049China

The high-temperature molten salt pump is the core equipment in a molten salt reactor that drives the flow of the molten salt *** stability is key to the continuous and reliable operation of the molten salt pump,and the liquid seal at the wear ring can affect the dynamic characteristics of the rotor *** the molten salt pump is operated in the hightemperature molten salt medium,thermal deformation of the submerged parts inevitably occurs,changing clearance between the stator and rotor,affecting the leakage and dynamic characteristics of the *** this study,the seal leakage,seal dynamic characteristics,and rotor system dynamic characteristics are simulated and analyzed using finite element simulation software based on two cases of considering the effect of seal thermal deformation effect or *** results show a significant difference in the leakage characteristics and dynamic characteristics of the seal obtained by considering the effect of seal thermal deformation and neglecting the effect of thermal *** leakage flow rate decreases,and the first-order critical speed of the seal-bearing-rotor system decrease after considering the seal’s thermal deformation.

关键词： High-temperature molten salt pump Seal thermal deformation Leakage characteristics Seal dynamic characteristics Critical speed

Convergence of Distributed Gradient-Tracking-Based Optimization Algorithms with Random Graphs

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Journal of Systems Science & Complexity 2021年第4期34卷 1438-1453页

作者： WANG Jiexiang fu Keli GU yu LI Tao School of Mechatronic Engineering and Automation Shanghai UniversityShanghai 200444China Key Laboratory of Pure Mathematics and Mathematical Practice School of Mathematical SciencesEast China Normal UniversityShanghai 200241China

This paper studies distributed convex optimization over a multi-agent system,where each agent owns only a local cost function with convexity and Lipschitz continuous *** goal of the agents is to cooperatively minimize a sum of the local cost *** underlying communication networks are modelled by a sequence of random and balanced digraphs,which are not required to be spatially or temporally independent and have any special *** authors use a distributed gradient-tracking-based optimization algorithm to solve the optimization *** the algorithm,each agent makes an estimate of the optimal solution and an estimate of the average of all the local *** values of the estimates are updated based on a combination of a consensus method and a gradient tracking *** authors prove that the algorithm can achieve convergence to the optimal solution at a geometric rate if the conditional graphs are uniformly strongly connected,the global cost function is strongly convex and the step-sizes don’t exceed some upper bounds.

关键词： Distributed optimization geometric convergence gradient tracking random graph

Barrier Lyapunov.function-Based Finite-Time Dynamic Surface Control for Output-Constrained Nonstrict-Feedback Systems

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Journal of Systems Science & Complexity 2023年第2期36卷 524-539页

作者： yu Jinpeng fu Cheng LIU Jiapeng MA yumei The College of Automation Qingdao UniversityQingdao 266003China Shandong Key Laboratory of Industrial Control Technology Qingdao UniversityQingdao 266003China The School of Control Science and Engineering Shandong UniversityJinan 250100China

This paper investigates a finite-time tracking problem for the uncertainty nonlinear systems in nonstrict-feedback form,in which the output signal is restricted in a *** on the barrier Lyapunov.function and dynamic surface control scheme,a novel adaptive neural controller is proposed by using the finite-time Lyapunov *** the aforementioned literature on finite time tracking control,the violation of system output constraint is avoided by combining the barrier Lyapunov.function method with finite-time *** structural characteristics of neural network is introduced to expand the adaptive neural finite-time backstepping method to the uncertainty nonlinear systems in the non-strict ***,the dynamic surface control is introduced to cope with the problem of“explosion of complexity”inherent in conventional backstepping *** is shown that the designed controller can achieve finite-time tracking control and all the variables in the closed-loop system are bounded with output constraint guaranteed form stability analysis and simulation results.

关键词： Adaptive neural network control explosion of complexity finite-time tracking nonstrictfeedback form

Evolution of copper species during heat treatment and its effect on CO oxidation reaction on CuCeZrO_(y) catalyst synthesized by a facile solvent-free route

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Journal of Rare Earths 2024年第4期42卷 660-667页

作者： Guangying fu Dongsen Mao Jun yu Qiangsheng Guo School of Chemical and Environmental Engineering Shanghai Institute of TechnologyShanghai21418 China The ZeoMat Group Qingdao Institute of Bioenergy and Bioprocess TechnologyCASQingdao26611China

Several ternary oxides CuCeZrO_(y)(CCZ)were synthesized by a facile grinding method followed by calcination at high temperatures,and used as catalysts for CO oxidation at low *** influences of calcination temperature(400-600℃)on the physicochemical properties of the assynthesized ternary oxides were investigated by thermogravimetric analysis/differential scanning calorimetry(TGA/DSC),X-ray diffraction(XRD),transmission electron microscopy(TEM),Raman,inductively coupled plasma-optical emission spectrometry(ICP-OES),N_(2) adsorption,H_(2)-temperature programmed reduction(H_(2)-TPR),and X-ray photoelectron spectroscopy(XPS)*** results show that the increase in calcination temperature from 400 to 500℃is conducive to the high dispersion of CuOx on catalyst surface and the incorporation of Cu species into the support to form the Cu-Ce-Zr-O solid *** raising of calcination temperature from 500 to 600℃,however,leads to the segregation of Cu species from the solid solution to aggregate on support surface and growth of highly dispersed CuOx *** highest catalytic activity is acquired over the CCZ calcined at 500℃,which can be ascribed to the largest contents of Cu+species and oxygen vacancies owing to the formation of the maximum amount of Cu-Ce-Zr-O solid solution.

关键词： CuCeZrO_(y)catalyst co oxidation Calcination temperature Grinding method Oxalate precursor Rare earths

Impact of Cloud Microphysical Processes on the Simulation of Typhoon Rananim near Shore. Part II： Typhoon Intensity and Track

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Acta meteorologica Sinica 2011年第4期25卷 456-466页

作者： CHENG Rui yu Rucong XU Youping fu yunfei State Key Laboratory of Numerical Simulation for Atmo3pheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics CAS Beijing 100029 Graduate School of the Chinese Academy of Sciences Beijing 100049 University of Science and Technology of China Hefei 230026

The impact of cloud microphysical processes on the simulated intensity and track of Typhoon Rananim is discussed and analyzed in the second part of this study. The results indicate that when the cooling effect due to evaporation of rain water is excluded, the simulated 36-h maximum surface wind speed of Typhoon Rananim is about 7 m s-1 greater than that from all other experiments; however, the typhoon landfall location has the biggest bias of about 150 km against the control experiment. The simulated strong outer rainbands and the vertical shear of the environmental flow are unfavorable for the deepening and maintenance of the typhoon and result in its intensity loss near the landfall. It is the cloud microphysical processes that strengthen and create the outer spiral rainbands, which then increase the local convergence away from the typhoon center and prevent more moisture and energy transport to the inner core of the typhoon. The developed outer rainbands are supposed to bring dry and cold air mass from the middle troposphere to the planetary boundary layer （PBL）. The other branch of the cold airflow comes from the evaporation of rain water itself in the PBL while the droplets are falling. Thus, the cut-off of the warm and moist air to the inner core and the invasion of cold and dry air to the eyewall region are expected to bring about the intensity reduction of the modeled typhoon. Therefore, the deepening and maintenance of Typhoon Rananim during its landing are better simulated through the reduction of these two kinds of model errors.

关键词： typhoon intensity cloud microphysical processes spiral rainband environmental wind shear

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A Peridynamic Model for Analyzing Fracture Behavior of functionally Graded Materials Used as an Interlayer

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Acta Mechanica Solida Sinica 2020年第6期33卷 781-792页

作者： Zhanqi Cheng Zhengqiang fu yu Zhang Hongxia Wu College of Civil Engineering Zhengzhou UniversityZhengzhou 450001China College of Mechanical Engineering Zhengzhou UniversityZhengzhou 450001China

functionally graded materials(FGMs)can be used els an *** interlayer connects two homogeneous materials and slows mutations in material properties,owing to the variability of parameters and *** this numerical simulation,a bond-based peridynamic(PD)model was used to perform dynamic fracture analysis of a continuous beam and a sandwiched structure with an FGM *** simulation results of two convergence studies,which include grid refinement(m-convergence)and the reducing radius of PD horizon(^-convergence),were *** a four-point bending load,the propagation behaviors of single pre-crack in the continuous beam with the FGM interlayer at different locations are simulated to compare with the experimental *** the sandwiched structure,the problems of a single crack and double cracks were *** numerical results show that the crack can deflect toward areas where the energy release rate is ***,the crack on the weak side for symmetric cracks only has fracture behavior,and if the double cracks are asymmetrical,all these cracks have fracture behaviors and propagation of the initial crack in the stiff region has a higher sensitivity than in the compliant region.

关键词： Peridynamic FGM interlayer Dynamic fracture Pre-crack Symmetric loads

Effect of relative humidity on the desulfurization performance of calcium-based desulfurizer

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Journal of Environmental Sciences 2024年第4期138卷 179-188页

作者： Juan Lǖ yu fu Haiyan yu HuanWang Zhe Wang Haiyan Chen School of Environment and Resource Southwest University of Science and TechnologyMianyang 621010China Guangyuan Emergency Management bureau Guangyuan 628000China

Low desulfurization efficiency impedes the wide application of dry desulfurization technology,which is a low-cost and simple process,and one significant solution is the development and manufacture of high-performance *** this study,firstly,a steam jet mill was used to digest quicklime;then,we utilized numerical simulation to study the flow field distribution and analyze the driving factors of quicklime digestion;and lastly,the desulfurization performance of the desulfurizer was evaluated under different relative *** results show that the desulfurizer prepared via the steam jet mill had better apparent activity than traditional ***,the entire jet flow field of the steam jet mill is in a supersonic and highly turbulent flow state,with high crushing intensity and good particle acceleration *** contact with the nascent surface maximizes the formation of slaked *** experiments demonstrated that the operating time with 100%desulfurization efficiency and the“break-through”time for the desulfurizer prepared via the steam jet mill is longer than that of traditional desulfurizers,and has significant advantages,especially at low flue gas relative *** with traditional desulfurizers,the desulfurizer prepared via steam jet mill expands the range of acceptable flue gas temperature,and the failure temperature is 1.625 times that of traditional *** work breaks through the technical bottleneck of low dry desulfurization efficiency,which is an important step in pushing forward the application of dry desulfurization.

关键词： Dry desulfurization Relative humidity Desulfurization efficiency High-efficiency desulfurizer Quicklime digestion

Digital fixed-frequency hysteresis current control of a BLDC motor applied for aerospace electrically powered actuators

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Chinese Journal of Aeronautics 2018年第6期31卷 1287-1297页

作者： Jian fu Yongling fu Liming yu Jianwen GUO Rongrong YANG Mingkang WANG School of Mechanical Engineering and Automation Beihang University Flying College Beihang University

In the conventional cascade control structure of aerospace electrically powered actuators, the current（or electromagnetic torque） loop plays a critical role in realizing a rapid response for a digitally controlled Brush Less Direct Current（BLDC） motor. Hysteresis Current Control（HCC） is an effective method in improving the performance of current control for a BLDC ***, the varying modulating frequency in the traditional HCC causes severe problems on the safety of power devices and the electromagnetic compatibility design. A triangular carrier-based fixed-frequency HCC strategy is expanded by relaxing the constraints on the rising and descending rates of the winding current to advance the capability of HCC to realize fixed-frequency modulation in the steady state. Based on that, a new flexible-bound-size quasi-fixed-frequency HCC is proposed, and the range feasible to realize fixed-frequency modulation control can cover the entire running process in the steady state. Meanwhile, a corresponding digital control strategy is designed,and four digitalization rules are proposed to extend the capacity to achieve fixed-frequency modulation control to the unsteady working state, that is, a novel fixed-frequency modulation is *** and experimental results prove the effectiveness of this improved fixed-frequency HCC strategy.

关键词： BLDC motor Current control Fixed-frequency modulation Flexible bound size Hysteresis current control PWM Triangular carrier

Pseudo-differential Operators and Generalized Lax Equations in Symbolic Computation

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Communications in Theoretical Physics 2008年第5期49卷 1139-1144页

作者： JIA Yi-Feng CHEN yu-fu School of Mathematical Sciences Capital Normal University Beijing 100037 China School of Mathematical Sciences Graduate University of the Chinese Academy of Sciences Beijing 100049 China

In this paper, the pseudo-differential operators and the generalized Lax equations in integrable systems are implemented in symbolic software Mathematica. A great deal of differential polynomials which appear in the procedure are dealt with by differential characteristic chain method. Using the program, several classical examples are given.

关键词： pseudo-differential operators generalized Lax equation Zakharov-Shabat equation integral systems hierarchy characteristic chain

Computational Fluid Dynamics Analysis of Shroud Design on Hemodynamic Performance and Blood Damage in a Centrifugal Blood Pump

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Computer Modeling in Engineering & Sciences 2018年第8期116卷 199-213页

作者： Guangliang Pan yu Chang Mingrui fu School of Life Science and BioEngineering Beijing University of TechnologyBeijing100124China.

Patients with extracorporeal membrane oxygenation still suffer from high rates of complication that linked to the flow field within the blood *** it is essential to optimise the geometry of the *** specification of shroud design is arguably the necessary design parameter in the centrifugal ***,the hemodynamic performances of the different shroud designs have not been studied *** this study,ten different shroud designs were made and divided into two groups as the different covering locations(A:Covering the blade leading edge,B:Covering the blade trailing edge).In every group,six shroud designs with the covering proportions of 0,1/5,2/5,3/5,4/5,1 were *** computational fluid dynamics(CFD)analyses were performed to investigate their effects on hemodynamics and hydraulic performance at the constant flow condition(4000 rpm,5 L/min).The percentage volumes of the scalar shear stress in specific threshold(τ9 Pa:the destruction of von Willebrand factor,τ>50 Pa:Platelet activation,τ>150 Pa:Break of red blood)were used to compare the blood damage of the different shroud ***,the modified index of hemolysis(MIH)were calculated based on a Eulerian approach for different *** simulations predicted an increase in the pump head,hydraulic efficiency,a fraction of fluid volume with scalar shear stress values above a threshold(9 Pa,50 Pa,150 Pa)and MIH with increasing shroud covering proportions from 0 to 1 in the same covering ***,these above results were higher in group B than group *** means that the risks of the hemolysis,thrombosis and bleeding increased as the rise of the covering proportion and they were higher in the pump whose shroud covers the blade trailing edge.

关键词： Computational fluid dynamics(CFD) hemodynamics centrifugal blood pump shroud design blood damage thrombosis hemolysis