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LES investigation of the tip vortex cavitating flow with special emphasis on the interaction between cavitation and vorticity by a modified cavitation model

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水动力学研究与进展B辑:英文版 2023年第3期35卷 594-606页

作者： Xin-ran Liu Tao Wang Xiao-Yang Zhao Tai-ran Chen School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China Beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China Vehicle Engineering Department Army Academy of Armored ForcesBeijing 100072China China Ship Research and Development Academy Beijing 100085China

Cavitation within the tip vortex(TV)flow remains a challenging issue in the design of high-speed and low-noise hydraulic machinery.In this paper,the TV cavitating flow around an elliptical hydrofoil is calculated by using large eddy simulation(LES)combined with a modified Schnerr-Sauer(S-S)cavitation model.The original S-S cavitation model is modified by taking into account the typical effect of vortex flow.The partial pressure term which can describe the vortex quantitatively and qualitatively is confirmed asρ_(m)ω^(2) x r _(c)^(2) ,and is considered into the R-P equation of the modified S-S cavitation model.Comparison between the numerical and experimental results shows good agreement in the form and evolution of cavities,including attached cavities(AC)and tip vortex cavities(TVC).The vorticity transport equation is utilized to investigate the dynamic mechanisms of the vortex development around the TVC.Further analyses indicate that cavitation in the TV flow influences the pressure in the core of the cavity and the local flow patterns.Typical vortex structures in the TV cavitating flow include TV,secondary vortex(SV)and wake vortex(WV).The direction and magnitude of the rotation effect can be described by axial vorticity which is drawn on the iso-surface of Q=1×105 s−2.The development of the TV cavitating flow can be divided into two stages:Stage I,the development and fusion of TV,SV,stage II,the dissipation of SV.The stretching term dominates the evolution of TV,and the dilatation term is the main reason in the mergence process of SV.

关键词： Cavitating flow tip vortex(TV) large eddy simulation(LES) cavitation model

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Experiment Study on the High-Temperature Thermal Treatment and Ultra-Low NOx Control of Solid Waste Coal Slime in Circulating Fluidized Bed

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Journal of Thermal Science 2022年第6期31卷 2244-2251页

作者： SONG Guoliang xiao Yuan yang zhao yang Xueting LYU Qinggang Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Dalian National Laboratory for Clean Energy Dalian 116023China

Coal slime is a kind of solid waste and inferior fuel, which is urgently needed to utilize. In this paper, a high-temperature thermal treatment of coal slime in a circulating fluidized bed(CFB) was attempted to achieve resource utilization. In the experiment, the combustion characteristics of dried coal slime during high-temperature thermal treatment were investigated in a 0.5 MW pilot-scale CFB. The stable fluidized combustion of dried coal slime was realized. When the excess air ratio was closer to 1.0, the furnace temperatures would be uniform. The ignition method of dried coal slime was changed correspondingly while the feeding position changed. However, feeding coal slime to the loop seal was instrumental in decreasing NO_(x) emissions. Moreover, the NO_(x) emissions were tried to further control by the post-combustion technology. Post-combustion technology could significantly reduce NO_(x) emissions below 50 mg·Nm^(-3) while ensuring combustion efficiency. Besides, it was found that there was an optimum excess air ratio in CFB of about 0.9 resulting in minimum NO_(x) emissions of coal slime. The experiment results could well guide the industrial-scale high temperature thermal treatment of coal slime.

关键词： solid waste coal slime thermal treatment CFB NOx post-combustion

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Method for Evaluating Bolt Competitive Failure Life Under Composite Excitation

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Chinese Journal of Mechanical Engineering 2023年第4期36卷 372-384页

作者： Guangwu yang Long yang Han zhao Haoxu Ding Bing yang Shoune xiao State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong UniversityChengdu 610031China

In this study,the competitive failure mechanism of bolt loosening and fatigue is elucidated via competitive failure tests on bolts under composite excitation.Based on the competitive failure mechanism,the mode prediction model and“load ratio-life prediction curve”(ξ-N curve)of the bolt competitive failure are established.Given the poor correlation of theξ-N curve,an evaluation model of the bolt competitive failure life is proposed based on Miner’s linear damage accumulation theory.Based on the force analysis of the thread surface and simulation of the bolt connection under composite excitation,a theoretical equation of the bolt competitive failure life is established to validate the model for evaluating the bolt competitive failure life.The results reveal that the proposed model can accurately predict the competitive failure life of bolts under composite excitation,and thereby,it can provide guidance to engineering applications.

关键词： Bolt Competitive failure life Evaluation model Mode prediction model Composite excitation

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Prussian blue analogues-derived nitrogen-doped carboncoated FeO/CoO hollow nanocages as a high-performance anode material for Li storage

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Rare Metals 2023年第12期42卷 4070-4080页

作者： Chen Liu Shuang Yuan yang yang xiao-Xi zhao xiao Duan Bin Cao Qiang Wang School of Metallurgy Northeastern UniversityShenyang 110819China Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of Education) Northeastern UniversityShenyang 110819China Key Laboratory of Electromagnetic Processing of Materials(Ministry of Education) Northeastern UniversityShenyang 110819China Department of Design and Engineering Faculty of Science and TechnologyBournemouth UniversityPooleDorset BH125BBUK

The design of electrode materials with specific structures is considered a promising approach for improving the performance of lithium-ion batteries(LIBs).In this paper,FeO/CoO hollow nanocages coated with a N-doped carbon layer(FCO@NC)was prepared using Fe-Co-based Prussian blue analogs(PBA)as a precursor.During the synthesis,dopamine was the carbon and nitrogen source.The reducing atmosphere was assured via NH_3/Ar,which regulated the vacancies in the structure of FCO@NC as well as increased its conductivity.When used as anode materials for LIBs,the FCO@NC nanocages deliver a high reversible capacity of 774.89 mAh·g^(-1)at 0.3 A·g^(-1)after200 cycles with a capacity retention rate of 80.4%and426.76 mAh·g^(-1)after 500 cycles at a high current density of 1 A·g^(-1).It is demonstrated that the hollow nanocage structure can effectively enhance the cycle stability,and the heat treatment in NH_(3)/Ar atmosphere contributes to the oxygen vacancy content of the electrode materials,further facilitating its conductivity and electrochemical performance.

关键词： Prussian blue analogue(PBA) Oxygen vacancy Hollow nanocage Nitrogen doping Lithium ion batteries(LIBs)

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Global Solutions and Interactions of Non-selfsimilar Elementary Waves for n-D Non-homogeneous Burgers Equation

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应用数学学报:英文版 2023年第4期39卷 830-853页

作者： Yuan-an zhao Gao-wei CAO xiao-zhou yang University of Chinese Academy of Sciences Beijing 100049China School of Mathematics and Statistics Hubei Minzu UniversityEnshi 445000China Wuhan Institute of Physics and Mathematics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071China

We investigate the global structures of the non-selfsimilar solutions for n-dimensional(n-D) nonhomogeneous Burgers equation, in which the initial data has two different constant states, which are separated by a(n-1)-dimensional sphere. We first obtain the expressions of n-D shock waves and rarefaction waves emitting from the initial discontinuity. Then, by estimating the new kind of interactions of the related elementary waves,we obtain the global structures of the non-selfsimilar solutions, in which ingenious techniques are proposed to construct the n-D shock waves. The asymptotic behaviors with geometric structures are also proved.

关键词： non-homogeneous burgers equation n-dimensional Riemann problem global singular structure non-selfsimilar solution interactions of elementary waves

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Dose reconstruction with Compton camera during proton therapy via subset-driven origin ensemble and double evolutionary algorithm

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Nuclear Science and Techniques 2023年第4期34卷 135-148页

作者： Zhi-yang Yao Yong-Shun xiao Ji-Zhong zhao Department of Engineering Physics Tsinghua UniversityBeijing 100084China Key Laboratory of Particle&Radiation Imaging(Tsinghua University) Ministry of EducationBeijing 100084China

Compton camera-based prompt gamma(PG) imaging has been proposed for range verification during proton therapy. However, a deviation between the PG and dose distributions, as well as the difference between the reconstructed PG and exact values, limit the effectiveness of the approach in accurate range monitoring during clinical applications. The aim of the study was to realize a PG-based dose reconstruction with a Compton camera, thereby further improving the prediction accuracy of in vivo range verification and providing a novel method for beam monitoring during proton therapy. In this paper, we present an approach based on a subset-driven origin ensemble with resolution recovery and a double evolutionary algorithm to reconstruct the dose depth profile(DDP) from the gamma events obtained by a cadmium-zinc-telluride Compton camera with limited position and energy resolution. Simulations of proton pencil beams with clinical particle rate irradiating phantoms made of different materials and the CT-based thoracic phantom were used to evaluate the feasibility of the proposed method. The results show that for the monoenergetic proton pencil beam irradiating homogeneous-material box phantom,the accuracy of the reconstructed DDP was within 0.3 mm for range prediction and within 5.2% for dose prediction. In particular, for 1.6-Gy irradiation in the therapy simulation of thoracic tumors, the range deviation of the reconstructed spreadout Bragg peak was within 0.8 mm, and the relative dose deviation in the peak area was less than 7% compared to the exact values. The results demonstrate the potential and feasibility of the proposed method in future Compton-based accurate dose reconstruction and range verification during proton therapy.

关键词： Prompt gamma imaging Dose reconstruction Range verification Origin ensemble Compton camera Evolutionary algorithm

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Coupling pinch analysis and rigorous process simulation for hydrogen networks with light hydrocarbon recovery

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Chinese Journal of Chemical Engineering 2021年第12期34卷 141-148页

作者： Minbo yang xiao Feng Liang zhao Shaanxi Key Laboratory of Energy Chemical Process Intensification School of Chemical Engineering and TechnologyXi’an Jiaotong UniversityXi'an 710049China Key Laboratory of Advanced Control and Optimization for Chemical Processes East China University of Science and TechnologyMinistry of EducationShanghai 200237China

In refineries,some hydrogen-rich streams contain considerable light hydrocarbons that are important raw materials for the chemical industry.Integrating hydrogen networks with light hydrocarbon recovery can enhance the reuse of both hydrogen and light hydrocarbons.This work proposes an automated method for targeting hydrogen networks with light hydrocarbon recovery.A pinch-based algebraic method is improved to determine the minimum fresh hydrogen consumption and hydrogen sources fed into the light hydrocarbon recovery unit automatically.Rigorous process simulation is conducted to determine the mass and energy balances of the light hydrocarbon recovery process.The targeting procedures are developed through combination of the improved pinch method and rigorous process simulation.This hybrid method is realized by coupling the Matlab and Aspen HYSYS platforms.A refinery hydrogen network is analyzed to illustrate application of the proposed method.The integration of hydrogen network with light hydrocarbon recovery further reduces fresh hydrogen requirement by463.0 m^(3)·h^(-1) and recovers liquefied petroleum gas and gasoline of 1711.5 kg·h^(-1) and 643 kg·h^(-1),respectively.A payback period of 9.2 months indicates that investment in light hydrocarbon recovery is economically attractive.

关键词： Hydrogen Light hydrocarbon recovery Pinch technology Simulation Systems engineering

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Joint optimization of inspection, maintenance, and spare ordering policy considering defective products loss

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Journal of Systems Engineering and Electronics 2021年第5期32卷 1167-1179页

作者： HAN Mengying yang Jianhua zhao xiao School of Economics and Management University of Science and Technology BeijingBeijing 100083China Beijing Enter-prise Low-Carbon Operation Strategy Research Base University of Science and Technology BeijingBeijing 100083China School of Business Hebei University of Economics and BusinessShijiazhuang 050061China

This paper proposes a joint inspection-based maintenance and spare ordering optimization policy that considers the problem of integrated inspection,preventive maintenance,spare ordering,and quality control for a four-state single-unit manufacturing system.When an inspection detects a minor defect,a second phase inspection is initiated and a regular order is placed.Product quality begins to deteriorate when the system undergoes a severe defect.To counter this,an advanced replacement of the minor defective system is carried out at the Jth second phase inspection.If a severe defect is recognized prior to the Jth inspection,or if system failure occurs,preventive or corrective replacement is executed.The timeliness of replacement depends on the availability of spare.We adopt two modes of ordering:a regular order and an emergency order.Meanwhile,a threshold level is introduced to determine whether an emergency order is preferred even when the regular order is already ordered but has not yet arrived.The optimal joint inspection-based maintenance and spare ordering policy is formulated by minimizing the expected cost per unit time.A simulation algorithm is proposed to obtain the optimal two-phase inspection interval,threshold level and advanced replacement interval.Results from several numerical examples demonstrate that,in terms of the expected cost per unit time,our proposed model is superior to some existing models.

关键词： maintenance two-phase inspection spare ordering three-stage failure process delay-time model

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The roles of microRNAs in regulating root formation and growth in plants

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Journal of Integrative Agriculture 2022年第4期21卷 901-916页

作者： YAN xiao-xiao LIU Xiang-yang CUI Hong zhao Ming-qin College of Tobacco Science Henan Agricultural University/National Tobacco Cultivation and Physiology and Biochemistry Research Center/Key Laboratory for Tobacco Cultivation of Tobacco IndustryZhengzhou 450002P.R.China

MicroRNAs(miRNAs) are small(ca. 20-24 nucleotides) non-coding RNAs that have recently been recognized as key post-transcriptional modulators of gene expression;and they are involved in many biological processes in plants, such as root growth and development. The miRNAs regulate root elongation, lateral root(LR) formation and adventitious root(AR) development in response to hormone signaling, nutrient uptake and biotic/abiotic stress. This review provides multiple perspectives on the involvement of miRNAs in regulating root growth and development in plants. We also discuss several crucial mechanisms of miRNAs, their relationships with transcription factors and the target gene-mediated hormone signaling interactions in the regulation of root growth and development.

关键词： microRNAs adventitious root lateral root primary root

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Cellulose sub-nanometric ribbons:A new generation of nanocellulose and platform for biomaterials

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Journal of Bioresources and Bioproducts 2024年第1期9卷 1-2页

作者： Shaomin Kang yang zhao Junlong Song Huining xiao Jiangsu Co-Innovation Center for Efficient Processing and Utilization of Forest Resources and International Innovation Center for Forest Chemicals and Materials Nanjing Forestry UniversityNanjing 210037China Department of Chemical Engineering University of New BrunswickFredericton NB E3B 5A3Canada

With the tremendous progress of research in nanoscience,much attention has been paid to the bottom of the“nano world”:scales around one nanometer or even smaller.In order to describe materials at this scale,a new co... 详细信息

关键词： biomaterials scales emerged

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