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The influence of various additives on coagulation process at different dosing point:From a perspective of structure properties

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Journal of Environmental Sciences 2021年第3期33卷 168-176页

作者： Yufei Li Lei Xu Tong Shi Wenzheng Yu Colleges of Forestry Northeast Forestry UniversityHarbin 150040China Key Laboratory of Drinking Water Science and Technology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100086China

Structure properties of flocs(size,fractal dimension(D_(f)),etc.)have a high impact on coagulation efficiency.In this work,the influences of three different additives(ferric salt(Fe),phosphate(P),and citric acid(CA))on coagulation process/efficiency were investigated.Results showed that a small amount of extra Fe can facilitate the growth of Al flocs by providing more'active sites'.Although zeta potential and D_(f) showed a limited change,the average floc size increased apparently and the increment was more obvious when Fe was added after the formation of the flocs.In contrast,P addition during the rapid mixing period will decrease the final average floc size,while the influence is less significant when P was added after the growth of the flocs.In terms of CA,a more striking negative effect on the growth ability of the flocs was observed compared to P.The strong complexing/coordination interactions between CA and aluminum hydroxide is the main reason behind the influence.CA also significantly decreased the D_(f) value of the flocs compared to P,and D_(f) showed a comparatively higher decrease when P or CA was added during the rapid mixing stage compared to the addition after the flocs formation.These results indicated that the addition of CA or P during the rapid mixing stage'inactivated'or occupied more'active sites'on the preliminarily formed Al NPs during the hydrolysis process,and therefore presented stronger impact on the morphology/size of the formed flocs.

关键词： Coagulation Floc size Additives Fractal dimension Zeta potential

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Impact of microorganism degradation on hydrocarbon generation of source rocks:A case study of the Bozhong Sag,Bohai Bay Basin

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Acta Oceanologica Sinica 2023年第3期42卷 243-253页

作者： Wei li yufei Gao Youchuan li China National Offshore Oil Corporation(CNOOC)Research Institute Co. Ltd.Beijing 100028China

The discovery of the Bozhong 19-6 gas field,the largest integrated condensate gas field in the eastern China in 2018,opened up a new field for the natural gas exploration deep strata in the Bohai Bay Basin,demonstrating there is a great potential for natural gas exploration in oil-type basins.The ethane isotope of the Bozhong 19-6 condensate gas is heavy,showing the characteristics of partial humic gas.In this paper,aimed at the source rocks of the Bozhong 19-6 gas field in the Bohai Bay Basin,the characteristics of the source rocks in the Bozhong 19-6 structural belt were clarified and the reason are explained from impact of microorganism degradation on hydrocarbon generation of source rocks why the condensate oil and gas had heavy carbon isotope and why it showed partial humic characteristics was explored based on the research of parent materials.The following conclusions were obtained:The paleontology of the Bozhong 19-6 structural belt and its surrounding sub-sags is dominated by higher plants,such as angiosperm and gymnosperm.During the formation of source rocks,under the intensive transformation of microorganism,the original sedimentary organic matter such as higher plants was degraded and transformed by defunctionalization.Especially,the transformation of anaerobic microorganisms on source rocks causes the degradation and defunctionalization of a large number of humic products such as higher plants and the increase of hydrogen content.The degradation and transformation of microorganism don't transform the terrestrial humic organic matter into newly formed“sapropel”hydrocarbons,the source rocks are mixed partial humic source rocks.As a result,hydrogen content incrased and the quality of source rocks was improved,forming the partial humic source rocks dominated by humic amorphous bodies.The partial humic source rocks are the main source rocks in the Bozhong 19-6 gas field,and it is also the internal reason why the isotope of natural gas is heavy.

关键词： Bozhong Sag natural gas types of source rocks Microorganism degradation hydrocarbon generation of source rocks

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Positioning error compensation of an industrial robot using neural networks and experimental study

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Chinese Journal of Aeronautics 2022年第2期35卷 346-360页

作者： Bo li Wei TIAN Chufan ZHANG Fangfang HUA Guangyu CUI Yufei Li College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Hebei Hanguang Industry Co. LtdHandan 056017China

Due to the characteristics of high efficiency,wide working range,and high flexibility,industrial robots are being increasingly used in the industries of automotive,machining,electrical and electronic,rubber and plastics,aerospace,food,etc.Whereas the low positioning accuracy,resulted from the serial configuration of industrial robots,has limited their further developments and applications in the field of high requirements for machining accuracy,e.g.,aircraft assembly.In this paper,a neural-network-based approach is proposed to improve the robots’positioning accuracy.Firstly,the neural network,optimized by a genetic particle swarm algorithm,is constructed to model and predict the positioning errors of an industrial robot.Next,the predicted errors are utilized to realize the compensation of the target points at the robot’s workspace.Finally,a series of experiments of the KUKA KR 500–3 industrial robot with no-load and drilling scenarios are implemented to validate the proposed method.The experimental results show that the positioning errors of the robot are reduced from 1.529 mm to 0.344 mm and from 1.879 mm to 0.227 mm for the no-load and drilling conditions,respectively,which means that the position accuracy of the robot is increased by 77.6%and 87.9%for the two experimental conditions,respectively.

关键词： Aircraft assembly Error compensation Industrial robot Neural network Robotic drilling

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Less pressure contributes to gravity-driven membrane ultrafiltration with greater performance:Enhanced driving efficiency and reduced disinfection by-products formation potential

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Journal of Environmental Sciences 2024年第3期137卷 407-419页

作者： Xiaoting Wu Yufei Li Zhaoyang Su Long Tian Muhammad Saboor Siddique Wenzheng Yu Colleges of Forestry Northeast Forestry UniversityHarbin 150040China State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China

Gravity-driven membrane(GDM)systems have been well developed previously;however,impacts of driving(i.e.,transmembrane)pressure on their performance received little attention,which may infuence GDM performance.In this study,we evaluated 4 GDM systems via altering the transmembrane pressure from 50 mbar to 150 mbar with 2 groups,treating surface water in Beijing,China.Results showed that less driving pressure was more favorable.Specifically,compared to groups(150 mbar),groups under a pressure of 50 mbar were found to have greater normalized permeability and lower total resistance.During the whole operation period,the quality of effuents was gradually improved.For example,the removal efficiency of UV254was significantly improved;particularly,under low driving pressure,the removal efficiency of UV254in PES GDM system increased by 11.91%,as compared to the corresponding system under high driving pressure.This observation was consistent with the reduction on disinfection by-products(DBPs)formation potential;groups under 50 mbar achieved better DBPs potential control,indicating the advantages of lower driving pressure.Biofilms were analyzed and responsible for these differences,and distinct distributions of bacteria communities of two GDM systems under 50 and 150 mbar may be responsible for various humic-like substances removal efficiency.Overall,GDM systems under less pressure should be considered and expected to provide suggestions on the design of GDM systems in real applications.

关键词： Ultrafiltration Gravity driven operation Membrane fouling Biofilms Disinfection by-products

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Pressure distribution feature-oriented sampling for statistical analysis of supercritical airfoil aerodynamics

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Chinese Journal of Aeronautics 2022年第4期35卷 134-147页

作者： Runze li yufei ZHANG Haixin CHEN School of Aerospace Engineering Tsinghua UniversityBeijing 100084China

In the field of supercritical wing design, various principles and rules have been summarized through theoretical and experimental analyses. Compared with black-box relationships between geometry parameters and performances, quantitative physical laws about pressure distributions and performances are clearer and more beneficial to designers. With the advancement of computational fluid dynamics and computational intelligence, discovering new rules through statistical analysis on computers has become increasingly attractive and affordable. This paper proposes a novel sampling method for the statistical study on pressure distribution features and performances, so that new physical laws can be revealed. It utilizes an adaptive sampling algorithm, of which the criteria are developed based on Kullback–Leibler divergence and Euclidean distance.In this paper, the proposed method is employed to generate airfoil samples to study the relationships between the supercritical pressure distribution features and the drag divergence Mach number as well as the drag creep characteristic. Compared with conventional sampling methods, the proposed method can efficiently distribute samples in the pressure distribution feature space rather than directly sampling airfoil geometry parameters. The corresponding geometry parameters are searched and found under constraints, so that supercritical airfoil samples that are well distributed in the pressure distribution space are obtained. These samples allow statistical studies to obtain more reliable and universal aerodynamic rules that can be applied to supercritical airfoil designs.

关键词： Adaptive sampling Output space Statistics Pressure distribution features Supercritical airfoil

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Optimization design of airfoils under atmospheric icing conditions for UAV

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Chinese Journal of Aeronautics 2022年第4期35卷 118-133页

作者： Haoran li yufei ZHANG Haixin CHEN School of Aerospace Engineering Tsinghua UniversityBeijing 100084China

Natural ice accretion on the lifting surface of an aircraft is detrimental to its aerodynamic performance, as it changes the effective streamlined body. The main focus of this work considers the optimization design of airfoils under atmospheric icing conditions for the Unmanned Aerial Vehicle(UAV). The ice formation process is simulated by the Eulerian approach and the three-dimensional Myers model. A three-equation turbulence model is implemented to accurately predict the stall performance of the iced airfoil. In recognition of the real atmospheric variability in the icing parameters, the medium volume diameter of supercooled water droplets is treated as an uncertainty with an assumed probability density function. A technique of polynomial chaos expansion is used to propagate the input uncertainty through the deterministic system. The numerical results show that the multipoint/multiobjective optimization strategy can efficiently improve both the ice tolerance and the cruise performance of an airfoil. The reason for the focus on robust optimization is that the ice angle of the optimized airfoil becomes less critical to the incoming flow.The optimized airfoils are applied to a UAV platform, in which the performance improvement and the relevant key flow feature are both preserved.

关键词： Aircraft icing Ice-accretion Ice-tolerant airfoil Optimization design Separated flow UAV

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Variable Stiffness Identification and Configuration Optimization of Industrial Robots for Machining Tasks

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Chinese Journal of Mechanical Engineering 2022年第5期35卷 275-290页

作者： Jiachen Jiao Wei Tian lin Zhang Bo li Junshan Hu Yufei Li Dawei li Jianlong Zhang Nanjing University of Aeronautics and Astronautics Nanjing 210016China Beijing Institute of Space Launch Technology Beijing 100076China Beijing Institute of Mechanical Equipment Beijing 100854China

Industrial robots are increasingly being used in machining tasks because of their high flexibility and intelligence.However,the low structural stiffness of a robot significantly affects its positional accuracy and the machining quality of its operation equipment.Studying robot stiffness characteristics and optimization methods is an effective method of improving the stiffness performance of a robot.Accordingly,aiming at the poor accuracy of stiffness modeling caused by approximating the stiffness of each joint as a constant,a variable stiffness identification method is proposed based on space gridding.Subsequently,a task-oriented axial stiffness evaluation index is proposed to quantitatively assess the stiffness performance in the machining direction.In addition,by analyzing the redundant kinematic characteristics of the robot machining system,a configuration optimization method is further developed to maximize the index.For numerous points or trajectory-processing tasks,a configuration smoothing strategy is proposed to rapidly acquire optimized configurations.Finally,experiments on a KR500 robot were conducted to verify the feasibility and validity of the proposed stiffness identification and configuration optimization methods.

关键词： Industrial robot Space gridding Variable stiffness identification Configuration optimization Smooth processing

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Optimization of multi-element airfoil settings considering ice accretion effect

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Chinese Journal of Aeronautics 2023年第2期36卷 41-57页

作者： Jinzhao DAI Haoran li yufei ZHANG Haixin CHEN School of Aerospace Engineering Tsinghua UniversityBeijing 100084China Beijing Electro-mechanical Engineering Institute Beijing 100074China

Almost half of all flight accidents caused by inflight icing occur at the approach and landing phases when high-lift devices are deployed.The present study focuses on the optimization of an ice-tolerant multi-element airfoil.Dual-objective optimization is carried out with critical hornshaped ice accumulated during the holding phase.The optimization results show that the present optimization method significantly enhances the iced-state and clean-state performance.The optimal multi-element airfoil has a larger deflection angle and wider gap at the slat and the flap compared with the baseline configuration.The sensitivity of each design parameter is analyzed,which verifies the robustness of the design.The design is further assessed when ice is accreted during the approach and landing phases,which also shows performance improvement.

关键词： Aircraft icing Airliner Ice-tolerant airfoil Multi-element airfoil Optimization design

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Parameter optimization for torsion spring of deployable solar array system with multiple clearance joints considering rigid–flexible coupling dynamics

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Chinese Journal of Aeronautics 2022年第3期35卷 509-524页

作者： Yuanyuan li Meng li Yufei LiU Xinyu GENG Chengbo CUI Qian Xuesen Laboratory of Space Technology China Academy of Space TechnologyBeijing 100094China

In this paper,four novel evaluation indices and corresponding hierarchical optimization strategies are proposed for a deployable solar array system considering panel flexibility and joint clearance.The deployable solar array model consists of a rigid main-body,two panels and four key mechanisms,containing torsion spring mechanism,closed cable loop mechanism,latch mechanism and attitude adjustment mechanism.Rigid and flexible components are established by Nodal Coordinate Formulation and Absolute Nodal Coordinate Formulation,respectively.The clearance joint model is described by nonlinear contact force model and amendatory Coulomb friction model.The latch time,stabilization time,maximum contact force and impulse sum of the contact force of the solar array system are selected as the four novel evaluation indices to represent the complex dynamic responses of a deployable solar array with clearance joints instead of the lock torque widely used in conventional works.To eliminate the gross errors caused by the nonlinear and nonsmooth mechanical properties,a hierarchical optimization strategy based on an adaptive simulated annealing algorithm and a nondominated sorting genetic algorithm is adopted for the solar array system with clearance joints.Results indicate that the effects of panel flexibility on the evaluation index responses and design optimization of the solar array system cannot be neglected.Besides,increasing the weight factor of the stabilization time index of the rigid system may compensate for the differences in optimal results of the rigid–flexible coupling system.That may provide some references for optimization design of deployable space mechanisms considering clearance joints.

关键词： Clearance joint Deployable solar array Evaluation index Parameter optimization Rigid-flexible coupling dynamics

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Benefiting others and self: Production of vitamins in plants

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Journal of Integrative Plant Biology 2021年第1期63卷 210-227页

作者： Yufei Li Chenkun Yang Hasan Ahmad Mohamed Maher Chuanying Fang Jie Luo National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research(Wuhan) Huazhong Agricultural UniversityWuhan 430070China College of Tropical Crops Hainan UniversityHaikou 570228China

Vitamins maintain growth and development in humans, animals, and plants. Because plants serve as essential producers of vitamins, increasing the vitamin contents in plants has become a goal of crop breeding worldwide. Here, we begin with a summary of the functions of vitamins. We then review the achievements to date in elucidating the molecular mechanisms underlying how vitamins are synthesized, transported, and regulated in plants. We also stress the exploration of variation in vitamins by the use of forward genetic approaches, such as quantitative trait locus mapping and genome-wide association studies. Overall, we conclude that exploring the diversity of vitamins could provide new insights into plant metabolism and crop breeding.

关键词： crop breeding forward genetic plants vitamins

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