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LBE simulation of impinging stream inside a T-junction mixer

Science China(Technological Sciences) 2018年第7期61卷 1038-1055页

作者： xu wenkai ZHANG QingChen GUI Nan ZHANG ZiWei College of Mechanical and Transportation Engineering China University of PetroleumBeijing 102249China Beijing National Railway Research&Design Institute of Signal&Communication Co. Ltd Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyKey Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China

Lattice Boltzmann Equation(LBE) method is utilized to simulate impinging stream(IS) in a T-junction mixer using a TD2G9 model. It aims to investigate the influence of Reynolds number(Re), aspect ratio of outlet diameter to inlet diameter, ratio of opposite inlet velocities, and the thermal boundary conditions on flow, mixing and heat transfer characteristics. In particular, the vortex evolution, velocity distribution, mixing index and Nusselt number(Nu) distribution in the T-junction mixer are explored in details. Four types of vortices and flow regimes are observed. The instantaneous and time-averaged flow and thermal fields,including vortex structure, transition of flow regimes, streamline and the Nusselt number distribution are discussed. Distinct quantitative transitions, even for dramatic change, are observed near the critical Re. At a low or moderate aspect ratio, the symmetric coherent structure is observed in an unstable flow regime. At a larger aspect ratio, the flow in the T-mixer becomes turbulent and asymmetric. The unequal injections velocities of the nozzles impose significant influence on the flow structure,mixing and heat transfer in vertical tube. Using larger difference between the two inlet velocities can result in more obvious change in flow characteristics. Moreover, mixing index is found to be valid in evaluating the mixing degree under a sinusoidal inlet velocity.

关键词： impinging flow lattice Boltzmann method T-junction heat transfer flow characteristics

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A novel policy iteration algorithm for solving the optimal consensus control problem of a discrete-time multiagent system with unknown dynamics

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Science China(Information Sciences) 2023年第8期66卷 269-270页

作者： wenkai xu Li WANG Shiwen SUN Chengyi XIA Zengqiang CHEN Tianjin Key Laboratory of Intelligence Computing and Novel Software Technology Tianjin University of Technology The Engineering Research Center of Learning-Based Intelligent System Ministry of Education College of Artificial Intelligence Nankai University

At present, an increasing number of researchers have noticed the importance of optimal consensus control(OCC) of multiagent systems(MASs) because of their rich practical applications in various areas [1–4]. To accomp...

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LBE-DEM coupled simulation of gas-solid two-phase cross jets

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Science China(Technological Sciences) 2013年第8期56卷 1377-1386页

作者： GUI Nan xu wenkai GE Liang YAN Jie Department of Thermal Energy Engineering College of Mechanical and Transportation EngineeringChina University of Petroleum China Academy of Space Technology

This paper establishes a lattice Boltzmann equation-discrete element method (LBE-DEM) coupled simulation method under the Eulerian-Lagrangian framework at first, and applies it to simulating a two-dimensional gas-solid two-phase cross jet. The gas phase is simulated by the lattice-Boltzmann method via the TD2G9 model; the solid phase is traced by the Lagrangian method and the inter-particle collision is calculated by the DEM method. Three values of the Stokes number St=10, 25, and 50 are simulated under the same mass loading. This paper focuses on the characteristics of vortex structure, particle distribution, and the reverse-flow/rebounding rate in cross jets. We analyze the characteristics of fluid vortex motion, particle cluster distribution, rebounding rate of particles and the influencing factors for them. The results show the existence of joint distribution of discrete clusters and discrete particles in cross jets. Meanwhile, it shows that a larger concentration of particles in the early stage of jet evolution or a smaller Stokes number under the same mass loading can produce a larger rebounding rate. However, the rebounding rate of particles at the late stage, in general, is stable.

关键词： gas-solid flow cross jet lattice Boltzmann discrete element method inter-particle collision

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LBE–DEM simulation of inter-phase heat transfer in gas–solid cross jets

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Chinese Science Bulletin 2014年第13期59卷 2486-2495页

作者： Nan Gui wenkai xu Liang Ge Jie Yan Department of Thermal Power Engineering College of Mechanical and Transportation Engineering China University of Petroleum China Academy of Space Technology

Lattice-Boltzmann equation(LBE)–Discrete element method(DEM)coupled simulation of a twodimensional gas–solid cross jet is performed,focusing on the gas-particle two-way coupling effect on heat transfer *** Reynolds number is 1000,and particle Stokes numbers are 10,25,and 50 under the same number flow rate of *** gas phase temperature field and particle distribution as well as the inter-phase heat transfer characteristics are studied and *** dominating effects,*** mean temperature difference and mean heat transfer coefficient between the gas–solid phases,for the pre-and post-collision stages of the cross jets are illustrated *** change of dominating roles is related to the dynamical response characteristics of particles.

关键词：交叉射流传热系数气固平均温度差粒子分布模拟波尔兹曼方程动态响应特性

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Association between arterial stiffness and risk of coronary artery disease in a community-based population

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Chinese Medical Journal 2014年第22期127卷 3944-3947页

作者： Zhang Yun Ye Ping Luo Leiming Bai Yongyi xu Ruyi Xiao wenkai Liu Dejun Wu Hongmei Department of Geriatric Cardiology Chinese People's Liberation Army General Hospital Beijing 100853 China

Background Arterial stiffness is well known as an important risk factor for coronary artery *** this study,we aimed to investigate the association between carotid-ankle pulse wave velocity （caPWV） and risk of coronary artery disease （CAD）,and the interaction between pulse wave velocity （PWV） and other potential risk factors of *** A community-based cross-sectional study was conducted for subjects living in Beijing,*** collected 213 subjects with coronary artery disease and 1 266 subjects without CAD between September 2007 and January 2009 in a community center of Beijing.A multivariate Logistic regression analysis was carried out to assess the odds ratios of factors related to *** We found CAD subjects were more likely to have a higher body massindex （BMI）,fasting glucose,uric acid,low-density lipoprotein （LDL） cholesterol,high-sensitivity Creactive protein （hs-CRP）,carotic-femoral pulse wave velocity （cfPWV） and caPWV （P ＜0.05）,and CAD subjects had a significantly lower HDL cholesterol levels （P ＜0.05）.Moreover,the proportion of hypertension in CAD subjects was significantly higher than non-CAD *** multiple Logistic regression analysis showed that hypertension,higher uric acid,hs-CRP,cfPWV and caPWV levels significantly increased the risk of CAD,with ORs （Cl） of 1.47 （1.25-1.74）,1.17 （1.01-1.26）,1.35 （1.10-1.67）,1.15 （1.09-1.19） and 1.07 （1.01-1.15）,*** HDL cholesterol was significantly associated with reduced risk of CAD,with ORs （CI） of 0.58 （0.40-0.83）.In addition,cfPWV had significant association with age,hypertension,LDL cholesterol,with Pearson＇s coefficients of 0.166,0.074,and 0.030,*** cfPWV and caPWV are independently associated with significant CAD,and cfPWV has significant correlation with age and *** and caPWV may be used as a practical tool for predicting the risk of CAD.

关键词： arterial stiffness pulse wave velocity coronary artery disease

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Cinobufacini regulates the composition of gut microbiota

Cinobufacini regulates the composition of gut microbiota

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2019年浙江省检验医学学术大会

作者： Yongfeng Bai Siwei Wang wenkai xu Shengmei Zhu Jun Lu Feng Zhang Quzhou People’s Hospital

Background: Cinobufacini, the sterilized hot water extraction of dried toad skin, has been widely used in the treatment of inflammation and cancers. Recently we found cinobufacini could ameliorate dextran sulfate sodi...

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柔性间隔发车下城轨网络换乘协同优化

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哈尔滨工业大学学报 2019年第9期51卷 68-73页

作者：宁丽巧赵鹏谢秉磊徐文恺哈尔滨工业大学(深圳)建筑学院广东深圳518055 北京交通大学交通运输学院北京100044

为提高城市轨道交通网络时刻表和客流需求的匹配性,采用柔性间隔发车策略以提高协同性能.以等间隔发车模式下列车发车相位确定发车基准点,并容许列车发车时刻在基准点附近可柔性调整一定范围,以最大化网络总换乘协同乘客数为目标构建了... 详细信息

为提高城市轨道交通网络时刻表和客流需求的匹配性,采用柔性间隔发车策略以提高协同性能.以等间隔发车模式下列车发车相位确定发车基准点,并容许列车发车时刻在基准点附近可柔性调整一定范围,以最大化网络总换乘协同乘客数为目标构建了基于柔性发车间隔的时刻表协同优化模型;考虑优化模型中存在大量0、1变量,模型求解困难,以各线路的列车发车相位以及各列车发车时刻的柔性偏移量为染色体设计了遗传算法来生成优化解.案例研究结果表明:遗传算法求解性能好,在等间隔发车时引入10%柔性,实现换乘协同乘客数提高11.85%.该方法可快速生成网络换乘协同时刻表方案,提高换乘节点效率,能满足大规模网络的求解需求.

关键词：城市轨道交通柔性发车间隔网络换乘协同混合整数线性规划遗传算法

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基于随机延误情景的城轨网络末班车时刻表调整模型

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铁道学报 2018年第8期40卷 28-33页

作者：徐文恺赵鹏宁丽巧张辉北京交通大学交通运输学院北京100044 山东建筑大学交通工程学院山东济南250101

在网络化运营条件下,末班车延误将严重影响乘坐末班车换乘乘客的正常出行。本文考虑乘客和运营两方面,以换乘成功乘客数量最大化和调整时刻表与计划时刻表偏离程度最小化为目标构建网络末班车时刻表调整模型,并采用ε-constraint法将模... 详细信息

在网络化运营条件下,末班车延误将严重影响乘坐末班车换乘乘客的正常出行。本文考虑乘客和运营两方面,以换乘成功乘客数量最大化和调整时刻表与计划时刻表偏离程度最小化为目标构建网络末班车时刻表调整模型,并采用ε-constraint法将模型转换为单目标混合整数线性规划模型,从而可使用Cplex软件编程求解近似Pareto最优解。以北京地铁网络为研究对象的案例分析表明,在随机延误情景下,本文提出的方法均能有效的提高换乘成功乘客数量。对近似Pareto最优解的进一步分析表明:随着调整时刻表与计划时刻表偏离程度的增加,换乘成功乘客数量会明显提高,但并不会导致末班车运行时间有明显变化。

关键词：城市轨道交通网络末班车时刻表调整随机延误 ε-constraint

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Cinobufacini ameliorates experimental colitis via modulating the composition of gut microbiota

Cinobufacini ameliorates experimental colitis via modulating...

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2019年浙江省医学会医学微生物与免疫学分会学术大会

作者： Yongfeng Bai Siwei Wang wenkai xu Yuanyuan Weng Shengmei Zhu Hao Sheng Jin Zhu Feng Zhang Department of Clinical Laboratory Quzhou People's Hospital Department of Core Facility Quzhou People's Hospital Department of Medical Information and Technology Quzhou People's Hospital Medical School Zhejiang University

Background:Cinobufacini,the sterilized hot water extraction of dried toad skin,has been widely used in the treatment of inflammation and *** we found cinobufacini could ameliorate dextran sulfate sodium(DSS)-induced colitis in mice,but the underlying mechanism was not fully *** current study,we explored the effect of cinobufacini on gut microbiota in DSS-induced acute colitic mouse model by pyrosequencing of colonic ***:C57 BL/6 mice were supplied with normal or 3.0% DSS containing drinking ***-treat mice were gavaged daily either with vehicle(water) or cinobufacini(10.0 or 30.0 mg/kg) for 7 *** composition of the gut microbiota was assessed by analyzing 16 S rRNA gene ***:Our data indicated that cinobufacini reversed DSS-induced gut dysbiosis and enhanced intestinal barrier ***,changing of some specific microbial groups such as Proteobacteria and Bacteroides was closely correlated with the re-establishment of intestinal equilibrium and the recovery of intestinal ***:Cinobufacini prevents colitis in mice by modifying the composition and function of gut *** current study provides additional mechanistic insight in the therapeutic effect of cinobufacini treatment and may pave the way for clinical application of cinobufacini in colitis therapy.

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金修饰磁性石墨烯基分子印迹复合材料的制备及对水中邻苯二甲酸二正丁酯的电化学传感检测

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高等学校化学学报 2019年第3期40卷 448-455页

作者：李颖康君君赵雪茹徐文凯齐琦天津工业大学环境与化学工程学院天津300387

以金修饰磁性石墨烯(Au@Fe3O4@RGO)为载体,通过表面分子印迹技术,选择水环境中邻苯二甲酸二正丁酯(DBP)为模板分子,制备了金修饰磁性石墨烯基分子印迹复合膜(Au@Fe3O4@RGO-MIP);通过扫描电子显微镜(TEM)、X射线衍射(XRD)、傅里叶变换红... 详细信息

以金修饰磁性石墨烯(Au@Fe3O4@RGO)为载体,通过表面分子印迹技术,选择水环境中邻苯二甲酸二正丁酯(DBP)为模板分子,制备了金修饰磁性石墨烯基分子印迹复合膜(Au@Fe3O4@RGO-MIP);通过扫描电子显微镜(TEM)、X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)等测试手段对其进行了分析表征.以Au@Fe3O4@RGO-MIP作为传感器识别元件的敏感材料,利用循环伏安(CV)、电化学阻抗谱(EIS)和差分脉冲(DPV)等电化学分析方法,对构建的分子印迹电化学传感器进行了性能分析,结果表明,该传感器对水环境中DBP的响应平衡时间为6 min,在0. 01～0. 1μmol/L范围内,DBP浓度与响应电流之间呈现良好的线性关系,检出限为0. 3049 nmol/L(S/N=3).

关键词：分子印迹技术石墨烯金纳米粒子传感器邻苯二甲酸酯

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