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Numerical investigations on performance improvement mechanism of a high-power vertical centrifugal pump with special emphasis on hydraulic component matching

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Journal of Hydrodynamics 2023年第4期35卷 649-667页

作者： Gang Yang Xi Shen de-sheng zhang Wen-hua Luo Jia Meng Xu-tao Zhao Research Center of Fluid Machinery Engineering and Technology Jiangsu UniversityZhenjiang212013China Key Laboratory of Fluid Machinery and Engineering Xihua UniversityChengdu610039China

The purpose of this paper is to investigate the performance improvement mechanism of a high power vertical centrifugal pump by using numerical ***,a comparative study of energy losses and internal flow characteristics in the original and optimized models was carried out with special attention to the hydraulic component *** optimized model(model B)was obtained by optimizing the vaned diffuser and volute based on the original model(model A),mainly the diffuser inlet diameter,diffuser inlet vane angle,volute channel inlet width and volute throat area were ***,the comparative results on performance and energy losses of two models showed that the efficiency and head of model B was significantly increased under design and part-load *** is mainly due to the dramatic reduction of energy loss PL in the diffuser and ***,the comparisons of PL and flow patterns in the vaned diffuser showed that the matching optimization between the model B impeller outlet flow angle and diffuser inlet vane angle resulted in a better flow pattern in both the circumferential and axial directions of the diffuser,which leads to the PL3 *** meridian velocity Vm of model B was significantly increased at diffuser inlet regions and resulted in improvements of flow patterns at diffuser middle and outlet regions as well as pressure expansion ***,the comparisons of PL and flow characteristics in the volute showed that the turbulence loss reduction in the model B volute was due to the flow pattern improvement at diffuser outlet regions which provided better flow conditions at volute inlet *** matching optimization between the diffuser and volute significantly reduced the turbulence loss in volute sections 1–4 and enhanced the pressure expansion capacity in sections 8–10.

关键词： High-power vertical centrifugal pump performance improvement mechanism hydraulic component matching flow pattern energy balance equation

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A differential control method for the proportional directional valve

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Journal of Zhejiang University-Science C(Computers and Electronics) 2014年第10期15卷 892-902页

作者： Bo JIN Ya-guang ZHU Wei LI de-sheng zhang Lu-lu zhang Fei-fei CHEN The State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Ningbo HOYEA Machinery Manufacture Co. Ltd.

For the proportional directional valve controlled by two proportional solenoids, the normal control method(NCM) energizes only one solenoid at a time. The performance of the valve is greatly influenced by the nonlinearity of the proportional solenoid, such as dead zone and low force gain with a small current, and this effect cannot be eliminated by a simple dead-zone current compensation. To avoid this disadvantage, we propose the differential control method(DCM). By employing DCM, the controller outputs differential signals to simultaneously energize both solenoids of the proportional valve, and the operating point is found by analyzing the force output of the two solenoids to make a minimum variation of the current force gain. The comparisons of the valve response characteristics are made between NCM and DCM by nonlinear dynamic simulation and experiments. Simulation and experimental results show that by using DCM, the frequency response of the valve is greatly enhanced, especially when the input is small, which means that the dynamic characteristics of the proportional valve are improved.

关键词： Differential control method Frequency response Proportional directional valve Spool displacement feedback

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Numerical investigation on the mechanism of impeller hub corner separation flow and induced energy loss in the bulb tubular pump

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Journal of Hydrodynamics 2023年第2期35卷 252-267页

作者： Long-yue Sun Qiang Pan de-sheng zhang Rui-jie Zhao B.P.M.(Bart)van Esch Research Center of Fluid Machinery Engineering and Technology Jiangsu UniversityZhenjiang212013China Wenling Fluid Machinery Technology Institute of Jiangsu University Wenling317525China department of Mechanical Engineering Eindhoven University of TechnologyEindhovenThe Netherlands Shimge Pump Industry(Zhejiang)Co. Ltd.Wenling317525China

Impeller hub corner separation flow(IHCS)has a significant influence on energy conversion of the bulb tubular pump,and its unsteady characteristics are investigated with CFD-based *** generation mechanism and power loss characteristics of IHCS are investigated by the entropy production method and pressure fluctuation *** main cause can be attributed to the large transverse pressure gradient near the hub at the trailing edge of the impeller,which is aggravated by the circumferential movement trend and the diffuser reverse flow,while the IHCS is significantly weakened with increased flow *** undesirable flow behavior is more likely to cause a significant increase in energy loss near the hub region compared to that in the rim *** relative vortex stretching induced by the velocity gradient is the main cause of the horn-like vortex(HLV),and its intensity and resulting energy loss tend to decrease along the vortex *** HLV changes the dominant frequency of the pressure fluctuations in the nearby flow field,the value of which increases from 1fr(the blade passing frequency)to 2fr with increased amplitude,mainly due to the lower pressure regions on the impeller suction surface(SS)and HLV vortex *** to the effect of rotor-stator interaction(RSI),the HLVs generated between two adjacent impeller blades are cut into several sections by the diffuser vanes and propagate and dissipate along the mainstream direction.

关键词： Bulb tubular pump corner separation entropy production pressure fluctuation visualization analysis

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design of Nonlinear decoupling Controller for Double-electromagnet Suspension System

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自动化学报 2006年第3期32卷 321-328页

作者： LIU de-sheng LI Jie zhang Kun College of Mechatronics Engineering and Automation National University of Defense Technology Changsha 410073

Aiming at the coupling characteristic between the two groups of electromagnets embedded in the module of the maglev train, a nonlinear decoupling controller is designed. The module is modeled as a double-electromagnet system, and based on some reasonable assumptions its nonlinear mathematical model, a MIMO coupling system, is derived. To realize the linearization and decoupling from the input to the output, the model is linearized exactly by means of feedback linearization, and an equivalent linear decoupling model is obtained. Based on the linear model, a nonlinear suspension controller is designed using state feedback. Simulations and experiments show that the controller can effectually solve the coupling problem in double-electromagnet suspension system.

关键词：双倍电磁体解耦悬浮控制器反馈控制器

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Fine tuning problem of the cosmological constant in a generalized Randall-Sundrum model

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Chinese Physics C 2020年第12期44卷 210-214页

作者： Guang-Zhen Kang de-sheng zhang Li Jun Hong-Shi Zong School of Science Yangzhou Polytechnic InstituteYangzhou 225127China department of Physics Nanjing UniversityNanjing 210093China School of Science Changzhou Institute of TechnologyChangzhou 213032China Joint Center for Particle Nuclear Physics and CosmologyNanjing 210093China State Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsCASBeijing 100190China

To solve the cosmological constant fine tuning problem,we investigate an(n+1)-dimensional generalized Randall-Sundrum brane world scenario with two(n−1)-branes instead of two *** an anisotropic metric ansatz,we obtain the positive effective cosmological constantΩeff of order 10−124 and only require a solution≃50−***,both the visible and hidden branes are stable because their tensions are ***,the fine tuning problem can be solved quite ***,the Hubble parameter H1(z)as a function of redshift z is in good agreement with the cosmic chronometers *** evolution of the universe naturally shifts from deceleration to *** suggests that the evolution of the universe is intrinsically an extra-dimensional *** can be regarded as a dynamic model of dark energy that is driven by the evolution of the extra dimensions on the brane.

关键词： cosmological constant fine tuning extra dimensions Hubble parameter

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Anisotropic evolution of 4-brane in a 6D generalized Randall-Sundrum model

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Chinese Physics C 2019年第9期43卷 101-107页

作者： Guang-Zhen Kang de-sheng zhang Long Du Jun Xu Hong-Shi Zong School of Science Yangzhou Polytechnic InstituteYangzhou 225127China department of Physics Nanjing UniversityNanjing 210093China School of Science Changzhou Institute of TechnologyChangzhou 213032China School of Science Guangxi University of Science and TechnologyLiuzhou 545006China Joint Center for Particle Nuclear Physics and CosmologyNanjing 210093China State Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsCASBeijing 100190China

We investigate a 6 D generalized Randall-Sundrum brane world scenario with a bulk cosmological *** stress-energy tensor Tabi on the brane is shown to be similar to a constant vacuum *** is consistent with the Randall-Sundrum model,in which each 3-brane Lagrangian yielded a constant vacuum *** adopting an anisotropic metric ansatz,we obtain the 5 D Friedmann-Robertson-Walker field *** a slightly later period,the expansion of the universe is proportional to the square root of time,t1/2,which is similar to the period of the radiation-dominated ***,we investigate the case with two a（t） and two b（t）.In a large range of t,we obtain the 3 D effective cosmological constant Λeff=-2Ω/3>0,which is independent of the integral ***,the scale factor is an exponential expansion,which is consistent with our present observation of the *** results demonstrate that it is possible to construct a model that solves the dark energy problem,while guaranteeing a positive brane tension.

关键词： brane induced cosmological constants anisotropy

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Cosmic acceleration caused by the extra-dimensional evolution in a generalized Randall-Sundrum model

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Chinese Physics C 2020年第11期44卷 213-219页

作者： Guang-Zhen Kang de-sheng zhang Chao Shi Long Du Dan Shan Hong-Shi Zong School of Science Yangzhou Polytechnic InstituteYangzhou 225127China department of Physics Nanjing UniversityNanjing 210093China School of Science Changzhou Institute of TechnologyChangzhou 213032China department of Nuclear Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 211106China School of Science Guangxi University of Science and TechnologyLiuzhou 545006China department of Physics Anhui Normal UniversityWuhu 241000China Nanjing Proton Research and design Center Nanjing 210093China

We investigate an(n+1)-dimensional generalized Randall-Sundrum model with an anisotropic metric which has three different scale *** obtains a positive effective cosmological constant Ωeff∼10^−124(in Planck units),which only needs a solution kr≃50−80 without fine *** the visible and hidden brane tensions are positive,which renders the two branes ***,we find that the Hubble parameter is close to a constant in a large region near its minimum,thus causing the acceleration of the ***,the scale of extra dimensions is smaller than the observed scale but greater than the Planck *** may suggest that the observed present acceleration of the universe is caused by the extra-dimensional evolution.

关键词： Hubble parameter extra dimensions anisotropic

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Exploring Mechanism of Electroacupuncture in Modulating Neuroinflammation Based on Intestinal Flora and Its Metabolites

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Chinese Journal of Integrative Medicine 2025年第2期31卷 183-192页

作者： YE Hai-min LI Zhuo-yan zhang Peng KANG Zhen ZHOU de-sheng School of Integrated Chinese and Western Medicine Hunan University of Chinese MedicineChangsha(410208)China Neurology department The Second Affiliated Hospital of Hunan University of Chinese MedicineChangsha(410005)China Acupuncture and Moxibustion Massage Rehabilitation department The Second Affiliated Hospital of Hunan University of Chinese MedicineChangsha(410005)China Neurology department The First Hospital of Hunan University of Chinese MedicineChangsha(410011)China

Neuroinflammatory responses play an important role in the pathogenesis of various diseases,particularly those affecting the central nervous *** of neuroinflammation is a crucial therapeutic strategy for the management of central nervous system *** intestinal microbial-gut-brain axis serves as a key regulatory pathway that modulates neuroinflammatory *** flora metabolites such as short-chain fatty acids,indoles and their derivatives,lipopolysaccharides,trimethylamine oxide,and secondary bile acids exert direct or indirect effects on *** have shown that electroacupuncture(EA)modulates the composition of the intestinal microbiota and its metabolites,while also suppressing neuroinflammation by targeting the TLR4/NF-κB,NLRP3/caspase-1,and microglial cell M2-type transformation *** review discusses the mechanisms by which EA regulates neuroinflammation via intestinal microbiota and its metabolites,providing information and a foundation for further investigation of the precise therapeutic mechanisms of EA in neurological disorders.

关键词： electroacupuncture intestinal flora metabolites of intestinal flora neuroinflammation nervous system disease review

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Biān stone hot compress combined with acupuncture at cervical Jiājǐ acupoint for axial pain after cervical LIF operation: A randomized controlled trial

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World Journal of Acupuncture-Moxibustion 2019年第4期29卷 264-268页

作者： de-sheng zhang Pei-rong Zhou Shui-chun Liu Shao-qiu Sun The Second Affiliated Hospital Hunan University of Traditional Chinese MedicineChangsha 410005China Hunan University of Traditional Chinese Medicine Changsha 410208China

Objective:To compare the clinical effect differences of biān(砭)stone hot compress combined with acupuncture at cervical Jiājǐ(夹脊EX-B2)acupoint and simple acupuncture at cervical EX-B2 for axial pain after cervical laminectomy with implant fixation(LIF)***:A total of 80 patients with axial pain after cervical LIF operation were randomly assigned into the biān(砭)stone hot compress combined with acupuncture at cervical EX-B2 group(Group A)and the acupuncture at cervical EX-B2 group(Group B),and 40 patients in each *** group A was treated by biān(砭)stone hot compress and acupuncture at cervical EX-B2,while the group B was treated by acupuncture at cervical *** of groups were treated once a day,one course of treatment consisted of 7 days,6-day treatment plus 1-day rest,and there were 3 courses of treatment in *** pain score(Visual analogue scale,VAS),neck dysfunction indices(NDI),and serum creatine phosphokinase(CPK)levels of patients were compared before and after the treatment,and their clinical effects were ***:The VAS score,NDI,and CPK in patients of the two groups after treatment were all lower than those before treatment(all P<0.05),and the indicators in the group A after treatment were all lower than those in the group B after treatment(all P<0.05).The effective rate in the group A was 92.5%,higher than that(77.5%)in the group B,and there was statistically significant difference(P<0.05).Conclusions:The biān(砭)stone hot compress combined with acupuncture at cervical EX-B2 acupoint was better than acupuncture at cervical EX-B2 alone in treatment of axial pain after cervical LIF *** the group A,therapeutic effects were improved by relieving pain,improving neck function,and repairing muscle injury.

关键词： Axial pain Biān(砭)stone Hot compress Acupuncture Cervical Jiājǐacupoint

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Axial coordinated iron-nitrogen-carbon as efficient electrocatalysts for hydrogen evolution and oxygen redox reactions

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Chinese Chemical Letters 2025年第1期36卷 637-642页

作者： Yanan Zhou Li sheng Lanlan Chen Wenhua zhang Jinlong Yang School of Material Science and Chemical Engineering Institute of Mass SpectrometryNingbo UniversityNingbo 315211China department of Chemical Physics University of Science and Technology of ChinaHefei 230026China department of Material Science and Engineering University of Science and Technology of ChinaHefei 230026China Hefei National Laboratory for Physical Sciences at the Microscale CAS Key Laboratory of Materials for Energy Conversion and Synergetic Innovation Centre of Quantum Information and Quantum PhysicsUniversity of Science and Technology of ChinaHefei 230026China

designing highly active electrocatalysts for the hydrogen evolution reaction(HER)and oxygen evolution and reduction reactions(OER and ORR)is pivotal to renewable energy ***,based on density functional theory(DFT)calculations,we systematically investigate the catalytic activity of iron-nitrogen-carbon based covalent organic frameworks(COF)monolayers with axially coordinated ligands(denotes as Fe N_(4)-X@COF,X refers to axial ligand,X=-SCN,-I,-H,-SH,-NO_(2),-Br,-ClO,-Cl,-HCO_(3),-NO,-ClO_(2),-OH,-CN and-F).The calculated results demonstrate that all the catalysts possess good thermodynamic and electrochemical *** different ligands axially ligated to the Fe active center could induce changes in the charge of the Fe center,which further regulates the interaction strength between intermediates and catalysts that governs the catalytic ***,FeN_(4)-SH@COF and Fe N_(4)-OH@COF are efficient bifunctional catalysts for HER and OER,FeN_(4)-OH@COF and FeN_(4)-I@COF are promising bifunctional catalysts for OER and *** findings not only reveal promising bifunctional HER/OER and OER/ORR catalysts but also provide theoretical guidance for designing optimum ironnitrogen-carbon based catalysts.

关键词： Axial coordinated ligands DFT calculation Hydrogen evolution reaction Oxygen evolution reaction Oxygen reduction reaction

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