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Chinese Journal of Chemical Engineering 2024年第2期66卷 60-70页

作者： Haozhe Yi taotao fu Chunying Zhu Youguang Ma State Key Laboratory of Chemical Engineering School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China

The adsorption process of droplets on the liquid-liquid interface and phase separation process can regulate the spatial distribution of the fluid system,which are crucial for chemical engineering.However,the cross-linking reaction,which is widely used in the field of polymers,can change the physical properties of the fluids and affect the flow behavior accordingly.A configuration of microchannels is designed to conveniently generate uniform droplets in one phase of the parallel flow.The flow behavior of the adsorption process of sodium alginate droplets on the liquid-liquid interface is investigated,and the subsequent process of phase separation is studied.In the process of droplet adsorption,the crosslinking reaction occurs synchronously,which makes the droplet viscosity and the elasticity modules of the droplet surface increase,thus affecting the dynamics of the adsorption process and the equilibrium shape of the droplet.The variation of the adsorption length with time is divided into three stages,which all conform to power law relationship.The exponents of the second and third stages deviate from the results of the Tanner's law.The flow pattern maps of droplet adsorption and phase separation are drawn,and the operating ranges of complete adsorption and complete separation are provided.This study provides a theoretical basis for further studying the flow behavior of droplets with cross-linking reaction in a microchannel.

关键词： Microfluidics Droplet Dynamics Crosslink Adsorption Separation

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Mass transfer intensification and mechanism analysis of gas–liquid two-phase flow in the microchannel embedding triangular obstacles

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Chinese Journal of Chemical Engineering 2022年第11期51卷 100-108页

作者： Xuanyu Nie Chunying Zhu taotao fu Youguang Ma State Key Laboratory of Chemical Engineering School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China

An effective mass transfer intensification method was proposed by embedding different triangular obstacles to improve the gas-liquid mass transfer efficiency in microchannel.The influences of triangle obstacles configuration,obstacle interval and flow rate on the volumetric mass transfer coefficient,pressure drop and energy consumption were investigated experimentally.The enhancement factor was used to quantify the mass transfer enhancement effect of triangle obstacles.It was found that the isosceles or equilateral triangle obstacles are superior to the rectangular obstacles.The maximum enhancement factor of equilateral triangle obstacles was 2.35.Considering comprehensively mass transfer enhancement and energy consumption,the isosceles triangle obstacle showed the best performance,its maximum enhancement factor was 2.1,while the maximum pressure drop increased only 0.41 kPa(22%)compared to the microchannel without obstacles.furthermore,a micro-particle image velocimetry(micro-PIV)was utilized to observe the flow field distribution and evolution,in order to understand and analyze the enhancement mechanism.The micro-PIV measurement indicated that the obstacle structure could induce the formation of vortex,which promotes convective mass transfer and thins the flow boundary layer,accordingly,the gas-liquid mass transfer efficiency is remarkably improved.This study can provide theoretical guidance and support for the design and optimization of microchannel with triangular obstacles.

关键词： Enhancement factor Microchannels Gas-liquid flow Mass transfer Triangular obstacle

Formation characteristics of Taylor bubbles in a T-junction microchannel with chemical absorption

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Chinese Journal of Chemical Engineering 2022年第6期35卷 214-222页

作者： Yaran Yin Xianming Zhang Chunying Zhu taotao fu Youguang Ma National Engineering Laboratory for Textile Fiber Materials and Processing Technology(Zhejiang) School of Materials Science and EngineeringZhejiang Sci-Tech UniversityHangzhou 310018China State Key Laboratory of Chemical Engineering School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China

This study focuses on the effect of chemical absorption on the formation dynamic characteristics and initial length of Taylor bubbles.The temporal evolutions of neck width and length of gaseous thread and initial length with and without chemical absorption were investigated with the Capillary number and Hatta number between 0.0010–0.0073 and 1.8–5.8 respectively.The squeezing regime with typical three stages,expansion,squeezing and pinch off is observed for both two processes.Compared with the nonabsorption process,the increase of formation time in the chemical absorption process arises mainly from the expansion stage,and the decrease of initial length is from the necking stage.In addition,the temporal length evolution satisfies the power-law scale with the same exponent but a smaller pre-exponential factor.The correlations of neck width for stage transition and initial length with Hatta number demonstrate the enhancement effect of chemical absorption on bubble formation dynamics and initial length at relatively high chemical reaction rates and long formation time.This study provides insight into the bubble formation mechanism and helps to regulate the bubble initial size with chemical absorption.

关键词： Microchannels Absorption Bubble Formation dynamics

Slug bubble deformation and its influence on bubble breakup dynamics in microchannel

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Chinese Journal of Chemical Engineering 2022年第10期50卷 66-74页

作者： Yingjie Fei Chunying Zhu taotao fu Xiqun Gao Youguang Ma State Key Laboratory of Chemical Engineering Tianjin UniversityTianjin 300072China Yifang Industry Corporation Liaoyang Petrochemical Fiber CompanyLiaoyang 111003China

The deformation of moving slug bubbles and its influence on the bubble breakup dynamics in microchannel were studied.Three bubble morphologies were found in the experiment:slug,dumbbell and grenade shapes.The viscosity effect of continuous phase aggravates the velocity difference between the fluid near the wall and the bubble,resulting in that the continuous phase near the bubble head flows towards and squeezes the bubble tail,which causes the deformation of bubbles.Moreover,the experimental results show that the deformation of bubbles could significa ntly prolo ng the bubble breakup period at the downstream Y-junction.There exists the critical capillary number Ca_(Cr )for the asymmetric breakup of grenade bubbles,Ca_(Cr )increases with the rise of flow rate and viscosity of the continuous phase.

关键词： Slug bubble Microchannel Bubble deformation Bubble breakup

Formation dynamics and size prediction of bubbles for slurry system in T-shape microchannel

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Chinese Journal of Chemical Engineering 2022年第5期35卷 153-161页

作者： Zhen Chen Chunying Zhu taotao fu Xiqun Gao Youguang Ma State Key Laboratory of Chemical Engineering School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China Yifang Industry Corporation Liaoyang Petrochemical Fiber CompanyLiaoyang 111003China

The bubble formation dynamics and size manipulation in the slurry of polystyrene microspheres in the microfluidic T-junction were visually investigated by a high-speed camera.Based on the evolution of the bubble neck with time,the formation process of bubbles is divided into three stages:filling,squeezing and pinch-off.The particle concentration has an obvious effect on the squeezing stage,while less impact on the filling and pinch-off stages.In the squeezing stage,the evolution of the dimensionless minimum neck width of bubbles with time could be described by a power-law relationship.The increase of the particle concentration or continuous phase flow rate could lead to the increase of body flow of the continuous phase and the enhancement of the squeezing force acted on the bubble neck,correspondingly,the power-law index a in the squeezing stage enlarges.Moreover,the bubble size increases with the increase of the gas phase flow rate and the decrease of the particle concentration and continuous phase flow rate.However,the effect of the particle concentration on the bubble size weakens with the increase of the continuous phase flow rate.In addition,a new prediction correlation of the bubble size for the slurry system in a T-shape microchannel was proposed with good prediction accuracy.

关键词： Microfluidic T-shape microchannel Bubble Slurry Dynamics

A Tutorial on Quantized Feedback Control

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IEEE/CAA Journal of Automatica Sinica 2024年第1期11卷 5-17页

作者： Minyue fu IEEE the School of System Design and Intelligent Manufacturing Shenzhen Key Laboratory of Control Theory and Intelligent Systems and Centre for Control Science and TechnologySouthern University of Science and TechnologyShenzhen 518055China

In this tutorial paper, we explore the field of quantized feedback control, which has gained significant attention due to the growing prevalence of networked control systems. These systems require the transmission of feedback information, such as measurements and control signals, over digital networks, presenting novel challenges in estimation and control design. Our examination encompasses various topics, including the minimal information needed for effective feedback control, the design of quantizers, strategies for quantized control design and estimation,achieving consensus control with quantized data, and the pursuit of high-precision tracking using quantized measurements.

关键词： Consensus control high-precision control networked control quantized estimation quantized feedback control robust control

Coupling Coordination Analysis of Cropland Intensification and Agroecosystem Services:Evidence from Loess Plateau in Shaanxi Province,China

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Chinese Geographical Science 2024年第3期34卷 401-419页

作者： fu Shaowu fu Mengyu QIU Menglong Center for Land Resource Research in Northwest China Shaanxi Normal UniversityXi’an 710119China

One of the greatest challenges in the agroecosystem is to improve cropland intensification while preserving agroecosystem services.While many studies have investigated the effect of cropland intensification on agroecosystem service,the interactive coupling and coordination among these factors remain largely unexplored.In view of this,this study performed a case study of the Loess Plateau in Shaanxi Province,China and constructed comprehensive evaluation models to quantify the cropland intensification and agroecosystem service in this area.Balance analysis and the coupling coordination degree model were used to evaluate the interactive relationship between cropland intensification and agroecosystem service,and statistical analysis and spatial autocorrelation were used to analyze the spatial characteristics and potential mechanism of the coupling coordination.Results show that both the cropland intensification and agroecosystem service in the study area were relatively low yet gradually increased from 2000 to 2020.Agroecosystem service lag was identified as the dominant unbalanced development type.Improving the supply capacity of agroecosystem services plays a key role in the balanced development of cropland in the Loess Plateau.The coupling coordination degree between cropland intensification and agroecosystem service ranges from basic coordination to serious incoordination.Therefore,cropland intensification practices in the area should be optimized to enhance this coordination degree.An upward trend was also observed in the coupling coordination degree from2000 to 2020.The withdrawal of marginal cropland in the Grain for Green program is one of the most important reasons for this trend,especially for the northern region.Around 83.6%of the high-high clusters are concentrated in the southern region of the Loess Plateau,whereas 70.5%of the low-low clusters are distributed in the northern region.These clustering characteristics are mainly attributed to the environmental suitability of these areas for agriculture and

关键词： cropland intensification agroecosystem services balance analysis coupling coordination degree Loess Plateau,China

A stochastic gradient-based two-step sparse identification algorithm for multivariate ARX systems

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Control Theory and Technology 2024年第2期22卷 213-221页

作者： Yanxin fu Wenxiao Zhao Key Laboratory of Systems and Control Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing100049China

We consider the sparse identification of multivariate ARX systems, i.e., to recover the zero elements of the unknown parameter matrix. We propose a two-step algorithm, where in the first step the stochastic gradient (SG) algorithm is applied to obtain initial estimates of the unknown parameter matrix and in the second step an optimization criterion is introduced for the sparse identification of multivariate ARX systems. Under mild conditions, we prove that by minimizing the criterion function, the zero elements of the unknown parameter matrix can be recovered with a finite number of observations. The performance of the algorithm is testified through a simulation example.

关键词： ARX system Stochastic gradient algorithm Sparse identification Support recovery Parameter estimation Strong consistency

Dynamics of 2×2 matrix non-Hermitian quantum systems on Bloch sphere

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Communications in Theoretical Physics 2024年第4期76卷 66-71页

作者： Libin fu Graduate School of China Academy of Engineering Physics Beijing 100193China

By casting evolution to the Bloch sphere,the dynamics of 2×2 matrix non-Hermitian systems are investigated in detail.This investigation reveals that there are four kinds of dynamical modes for such systems.The different modes are classified by different kinds of fixed points,namely,the elliptic point,spiral point,critical node,and degenerate point.The Hermitian systems and the unbroken PT non-Hermitian cases belong to the category with elliptic points.The degenerate point just corresponds to the systems with exceptional point(EP).The topological properties of the fixed point are also discussed.It is interesting that the topological charge for the degenerate point is two,while the others are one.By casting evolution to the Bloch sphere,the dynamics of 2×2 matrix non-Hermitian systems are investigated in detail.This investigation reveals that there are four kinds of dynamical modes for such systems.The different modes are classified by different kinds of fixed points,namely,the elliptic point,spiral point,critical node,and degenerate point.The Hermitian systems and the unbroken non-Hermitian cases belong to the category with elliptic points.The degenerate point just corresponds to the systems with exceptional point(EP).The topological properties of the fixed point are also discussed.It is interesting that the topological charge for the degenerate point is two,while the others are one.

关键词： non-Hermitian quantum system two-level system dynamics on the Bloch sphere PT-symmetry fixed points

Oligodendrocytes in central nervous system diseases:the effect of cytokine regulation

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Neural Regeneration Research 2024年第10期19卷 2132-2143页

作者： Chengfu Zhang Mengsheng Qiu Hui fu Center for Cognition and Brain Disorders The Affiliated Hospital of Hangzhou Normal UniversityHangzhouZhejiang ProvinceChina Department of Psychiatry National Clinical Research Center for Mental Disordersand National Center for Mental DisordersThe Second Xiangya Hospital of Central South UniversityChangshaHunan ProvinceChina Institute of Life Sciences Key Laboratory of Organ Development and Regeneration of Zhejiang ProvinceCollege of Life and Environment SciencesHangzhou Normal UniversityHangzhouZhejiang ProvinceChina Key Laboratory of Aging and Cancer Biology of Zhejiang Province School of Basic Medical SciencesHangzhou Normal UniversityHangzhouZhejiang ProvinceChina

Cytokines including tumor necrosis factor, interleukins, interferons, and chemokines are abundantly produced in various diseases. As pleiotropic factors, cytokines are involved in nearly every aspect of cellular functions such as migration, survival, proliferation, and differentiation. Oligodendrocytes are the myelin-forming cells in the central nervous system and play critical roles in the conduction of action potentials, supply of metabolic components for axons, and other functions. Emerging evidence suggests that both oligodendrocytes and oligodendrocyte precursor cells are vulnerable to cytokines released under pathological conditions. This review mainly summarizes the effects of cytokines on oligodendrocyte lineage cells in central nervous system diseases. A comprehensive understanding of the effects of cytokines on oligodendrocyte lineage cells contributes to our understanding of central nervous system diseases and offers insights into treatment strategies.

关键词： astrocyte central nervous system disease CXC chemokine cytokine interferonγ interleukin microglia oligodendrocyte oligodendrocyte precursor cell tumor necrosis factorα