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Effect of operational and geometric parameters on the hydrodynamics of a Wurster coater:A CFD-DEM study

Particuology 2024年第2期85卷 62-76页

作者： Yinqiang Song Tuo Zhou Ruiqi Bai man zhang Hairui Yang Department of Energy and Power Engineering Tsinghua UniversityBeijing100084China Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Tsinghua UniversityBeijing100084China State Key Laboratory of Power System and Generation Equipment Tsinghua UniversityBeijing100084China

A coupled CFD-DEM method was used to study the hydrodynamics of a Wurster coater.Firstly,the CFD part of the model was validated by the accurate prediction of the pressure drops over a pseudo-2D fluidized bed under various gas velocities.The effect of gas velocity,gap height,tube length and batch volume of the particles on the cycle time and the residence time of the particles was thoroughly investigated.The central jet gas velocity ui was found to speed up the particle cycle but undermine the coating efficiency.The gas velocity at the horizontal transport zone u2 was able to promote the horizontal transport of the particles but should not be too high,otherwise,it would obstruct the normal falling back of the particles in the downward zone.Big gap heights would decrease the coating efficiency but tube length had little impact on that.The increment of batch volume would commonly abase the cycle time and the working efficiency under a given u1.The de-fluidization problem arose when the batch volume increased to 550 mL.However,this problem could be swept out by the optimization of u1 and u2.In a mixture of different sizes,the coarse particles enjoyed higher coating efficiency and could travel closer to the nozzles.This may shield the fine particles from getting enough coating liquids,and thus coarse particles and fine particles were not recommended to get coated in the same batch.

关键词： Numerical simulation CFD-DEM Wurster coater Hydrodynamics Cycle time Residence time

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Laser-upgraded coal tar for smart pavements in road and bridge monitoring applications

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Microsystems & Nanoengineering 2024年第2期10卷 231-239页

作者： Jincai Huang man zhang Haoyun He Qingang Li Yixin Zhao Qiulin Tan Xining Zang Department of Mechanical Engineering Tsinghua UniversityBeijing100084China State Key Laboratory of Clean and Efficient Turbomachinery Power Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing100084China Key Laboratory for Advanced Materials Processing Technology Ministry of EducationBeijing100084China Science and Technology on Electronic Test and Measurement Laboratory North University of ChinaTaiyuan030051China School of Energy and Mining Engineering China University of Mining and Technology(Beijing)Beijing100083China

The implementation of an intelligent road network system requires many sensors for acquiring data from roads,bridges,and vehicles,thereby enabling comprehensive monitoring and regulation of road networks.Given this large number of required sensors,the sensors must be cost-effective,dependable,and environmentally friendly.Here,we show a laser upgrading strategy for coal tar,a low-value byproduct of coal distillation,to manufacture flexible strain-gauge sensors with maximum gauge factors of 15.20 and 254.17 for tension and compression respectively.Furthermore,we completely designed the supporting processes of sensor placement,data acquisition,processing,wireless communication,and information decoding to demonstrate the application of our sensors in traffic and bridge vibration monitoring.Our novel strategy of using lasers to upgrade coal tar for use as a sensor not only achieves the goal of turning waste into a resource but also provides an approach to satisfy large-scale application requirements for enabling intelligent road networks.

关键词： gauge bridge smart

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Microbial communities and their influencing factors in the sediment of upper and mid-lower reaches of the Yellow River

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Journal of Earth Science 2024年

作者： Yanmin zhang Zewei Gui Xiaofei Gao Jingxiao zhang Yunni Gao man zhang Guokun Yang Xindang zhang Xulu Chang Zixuan Gan Xiaolin Meng Xuejun Li Hongchen Jiang College of Fisheries Henan Normal University State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences Wuhan College of Agricultural and Environmental Sciences University of California Davis

Sedimentary microbial communities play an important role in driving biogeochemical cycles in river ecosystems. However， limited is known about the microbial variation and its influencing factors in the high-turbid Yellow River. In this study， microbial communities and their influencing factors in the sediment of upper and mid-lower reaches of the Yellow River were examined. The results showed that Gammaproteobacteria were most dominant in Yellow River sediments. Deltaproteobacteria， Nitrospirae and family of Bacillaceae， Geobaceraceae were more abundant in the mid-lower reaches， while Gammaproteobacteria， Verrucomicrobia and family of Caldilineaceae， Llumatobacteraceae were more abundant in the upper reaches. The microbial communities were predominantly affected by nutrient factors (NH4+， TN and TP)， followed by the spatial factors and Chla content in the mid-lower reaches， while they were by predominantly affected by spatial factors， followed by the nutrient factors and Chla content in the upper reaches. The dominant microbial taxa were mostly correlated with COD， NH4+， TP and temperature. In summary， the sedimentary microbial communities differ between the upper and mid-lower reaches and respond differently to the environmental and spatial factors in the sediment of the Yellow River.

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Influence of the Acoustic Liner in Large Eddy Simulation of Longitudinal Thermoacoustic Instability in a Model Annular Combustor

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Journal of Thermal Science 2024年第2期33卷 710-724页

作者： MENG Sheng zhang man GAO Yi AECC Commercial Aircraft Engine Co. Ltd.Shanghai200241China School of Aeronautics and Astronautics Shanghai Jiao Tong UniversityShanghai200240China

Although extensive efforts have been made to dampen the thermoacoustic instability,successfully controlling the pressure oscillations in modern gas turbines or aeroengines remains challenging.The influence of the acoustic liner on the longitudinal thermoacoustic mode in a model annular combustor is investigated by Large Eddy Simulation(LES) in this work.The result of the self-excited longitudinal thermoacoustic instability without the liner agrees well with the frequency and acoustic analysis of the pressure mode based on experimental data.Three different bias flow velocities of the liner located downstream of the combustor are then simulated.The results reveal that the existence of the liner influences not only the acoustic field but also the flow field.When the bias velocity is large,it leads to intense turbulence-induced fluctuations,and the pressure oscillation is modulated intermittently.It shows that the weak coupling between flow and pressure oscillations plays a significant role in the onset of the intermittency of a thermoacoustic system.Based on the dynamic analysis of the thermoacoustic system with the acoustic liner,this intermittency is caused by the influence of the flow field on the flame-acoustic coupling.Finally,a low-order modeling method based on Van der Pol(VdP) oscillator with additive stochastic forcing is conducted to reproduce the evolving dynamics of the thermoacoustic system.Although the numerical cases demonstrated in this work are relatively simpler than those in a practical combustion system,the results are helpful for us to understand the effect of the acoustic liner and show the attractive potential to apply this device to suppress thermoacoustic instability.

关键词： thermoacoustic instability acoustic liner Large Eddy Simulation low-order modeling

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Exceptional points enhance sensing in silicon micromechanical resonators

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Microsystems & Nanoengineering 2024年第1期10卷 17-25页

作者： man-Na zhang Lei Dong Li-Feng Wang Qing-An Huang Key Laboratory of MEMS of the Ministry of Education Southeast UniversityNanjing 210096China

Exceptional points(EPs)have recently emerged as a new method for engineering the response of open physical systems,that is,systems that interact with the environment.The systems at the EPs exhibit a strong response to a small perturbation.Here,we show a method by which the sensitivity of silicon resonant sensors can be enhanced when operated at EPs.In our experiments,we use a pair of mechanically coupled silicon micromechanical resonators constituting a parity-time(PT)-symmetric dimer.Small perturbations introduced on the mechanically coupled spring cause the frequency to split from the EPs into the PT-symmetric regime without broadening the two spectrum linewidths,and this frequency splitting scales with the square root of the perturbation strength.The overall signal-tonoise ratio is still greatly enhanced,although the measured noise spectral density of the EP sensing scheme has a slight increase comparable to the traditional counterpart.Our results pave the way for resonant sensors with ultrahigh sensitivity.

关键词： resonant symmetric points

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An Efficient Optimization Design Framework for Low-Resistance Shape of Bionic Amphibious Robot

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China Ocean Engineering 2024年第1期38卷 117-128页

作者： zhang Dai-yu zhang man-yu WANG Zhi-dong ZHENG Wen-sheng LING Hong-jie HU Jun-ming School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China

To realize the low-resistance shape optimization design of amphibious robots,an efficient optimization design framework is proposed to improve the geometric deformation flexibility and optimization efficiency.In the proposed framework,the free-form deformation parametric model of the flat slender body is established and an analytical calculation method for the height constraints is derived.CFD method is introduced to carry out the high-precision resistance calculation and a constrained Kriging-based optimization method is built to improve the optimization efficiency by circularly infilling the new sample points which satisfying the constraints.Finally,the shape of an amphibious robot example is optimized to get the low-resistance shape and the results demonstrate that the presented optimization design framework has the advantages of simplicity,flexibility and high efficiency.

关键词： amphibious robot optimization method free-form deformation CFD-based hydrodynamic calculation

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Field estimation of maize plant height at jointing stage using an RGB-D camera

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The Crop Journal 2022年第5期10卷 1274-1283页

作者： Ruicheng Qiu man zhang Yong He College of Biosystem Engineering and Food Science Zhejiang UniversityHangzhou 310058ZhejiangChina Key Laboratory of Modern Precision Agriculture System Integration Research Ministry of EducationChina Agricultural UniversityBeijing 100083China

Plant height can be used for assessing plant vigor and predicting biomass and yield. manual measurement of plant height is time-consuming and labor-intensive. We describe a method for measuring maize plant height using an RGB-D camera that captures a color image and depth information of plants under field conditions. The color image was first processed to locate its central area using the S component in HSV color space and the Density-Based Spatial Clustering of Applications with Noise algorithm. Testing showed that the central areas of plants could be accurately located. The point cloud data were then clustered and the plant was extracted based on the located central area. The point cloud data were further processed to generate skeletons, whose end points were detected and used to extract the highest points of the central leaves. Finally, the height differences between the ground and the highest points of the central leaves were calculated to determine plant heights. The coefficients of determination for plant heights manually measured and estimated by the proposed approach were all greater than 0.95. The method can effectively extract the plant from overlapping leaves and estimate its plant height. The proposed method may facilitate maize height measurement and monitoring under field conditions.

关键词： Maize plant heigh Kinect Maize central area Point cloud data Image processing

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Highly efficient generation of blastocyst-like structures from spliceosomes-repressed mouse totipotent blastomere-like cells

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Science China(Life Sciences) 2023年第3期66卷 423-435页

作者： Pengfei zhang Xuzhao Zhai Boyan Huang Shu Sun Wen Jing Wang man zhang GMU-GIBH Joint School of Life Sciences The Guangdong-Hong Kong-Macao Joint Laboratory for Cell Fate Regulation and DiseasesThe Fifth Affiliated Hospital of Guangzhou Medical UniversityGuangzhou LaboratoryGuangzhou Medical UniversityGuangzhou 510005China Center for Cell Lineage and Atlas(CCLA) Bioland LaboratoryGuangzhou Regenerative Medicine and Health Guangdong LaboratoryGuangzhou 510005China

Mammalian embryogenesis begins with a totipotent zygote.Blastocyst-like structures can be captured by aggregated cells with extended pluripotent properties in a three-dimensional(3D)culture system.However,the efficiency of generating blastoids is low,and it remains unclear whether other reported totipotent-like stem cells retain a similar capacity.In this study,we demonstrated that spliceosomal repression-induced totipotent blastomere-like cells(TBLCs)form blastocyst-like structures within around 80%of all microwells.In addition,we generated blastoids initiating from a single TBLC.TBLC-blastoids express specific markers of constituent cell lineages of a blastocyst and resemble blastocyst in cell-lineage allocation.Moreover,singlecell RNA sequencing revealed that TBLC-blastoids share a similar transcriptional profile to natural embryos,albeit composed of fewer primitive endoderm-like cells.Furthermore,TBLC-blastoids can develop beyond the implantation stage in vitro and induce decidualization in vivo.In summary,our findings provided an alternative cell type to efficiently generate blastoids for the study of early mouse embryogenesis.

关键词： blastoids TBLCs early embryogenesis totipotent

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An empirical model for high energy density lithium-(ion)batteries with ultra-thick electrodes

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Tungsten 2024年第1期6卷 230-237页

作者： Li-Ming Jin Guang-Guang Xing Nan Qin Yan-Yan Lu Jun-Sheng Zheng Cun-man zhang Jim P.Zheng School of Automotive Studies and Clean Energy Automotive Engineering Center Tongji UniversityShanghai 201804China Department of Electrical Engineering University at BuffaloThe State University of New YorkBuffaloNY 14260USA

Increasing the electrode thickness is a significant method to decrease the weight and volume ratio of the inactive components for high energy density of the devices.In this contribution,we extracted a repeating unit in the configurations and establish the empirical energy density model based on some assumptions.In this model,the effects of the electrode thickness on the energy density for lithium-ion batteries(LIBs),lithium metal batteries(LMBs),and anode-free lithium batteries(ALBs)are evaluated quantitively with the current parameters of the batteries.The results demonstrate that the structure evolutions from LIBs,LMBs to ALBs with the reduction of the anode weight contribution,the energy density can be well improved exactly.While the increase of the thickness of the electrode provide another route to furthe r enhance the energydensity by decreasing the weight contribution of inactive materials;meanwhile the effects for ALBs are higher than LMBs and LIBs due to the higher weight ratio of inactive materials.This empirical energy density model is also applied into the practical system and provide intuitional results to guide the battery design for higher energy density.

关键词： Empirical model High energy density Lithium batteries Ultra-thick electrodes

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Electrodeposited 3D hierarchical NiFe microflowers assembled from nanosheets robust for the selective electrooxidation of furfuryl alcohol

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Green Energy & Environment 2023年第3期8卷 874-882页

作者： Biying Liu man zhang Yaoyu Liu Yuchen Wang Kai Yan Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology School of Environmental Science and EngineeringSun Yat-sen University135 Xingang Xi RoadGuangzhou510275China

A robust and green strategy for the selective upgrading of biomass-derived platform chemicals towards highly valuable products is important for the sustainable development.Herein,the efficient electrocatalytic oxidation of biomass-derived furfuryl alcohol(FFA)into furoic acid(FurAc)catalyzed by the electrodeposited non-precious NiFe microflowers was successfully reached under the low temperature and ambient pressure.The 3D hierarchical NiFe microflowers assembled from ultrathin nanosheets were controllably synthesized by the electrodeposition method and uniformly grown on carbon fiber paper(CFP).Electrochemical analysis confirmed that NiFe nanosheets more preferred in the selective oxidation of FFA(FFAOR)than oxygen evolution reaction(OER).The linear sweep voltammetry(LSV)in FFAOR displayed a clear decrease towards lower potential,resulting in 30 mV reduction of overpotential at 20 mA cm^(-2) compared with that of OER.The optimal catalyst Ni_(1)Fe_(2) nanosheets exhibited the highest selectivity of FurAc(94.0%)and 81.4%conversion of FFA within 3 h.Besides,the influence of various reaction parameters on FFAOR was then explored in details.After that,the reaction pathway was investigated and rationally proposed.The outstanding performance for FFAOR can be ascribed to the unique structure of 3D flower-like NiFe nanosheets and oxygen vacancies,resulting in large exposure of active sites,faster electron transfer and enhanced adsorption of reactants.Our findings highlight a facile and convenient mean with a promising green future,which is promising for processing of various biomass-derived platform chemicals into value-added products.

关键词： Electrodeposition Microflowers assembled by nanosheets NiOOH Oxygen vacancies Electrochemical oxidation Furfuryl alcohol Furoic acid

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