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CFD Simulation of Local and Global Mixing Time in an Agitated Tank

Chinese Journal of Mechanical Engineering 2017年第1期30卷 118-126页

作者： li liangchao XU Bin Key Laboratory of Testing Technology for Manufacturing Process of Ministry of Education Southwest University of Science and TechnologyMianyang 621010China

The Issue of mixing efficiency in agitated tanks has drawn serious concern in many industrial processes. The turbulence model is very critical to predicting mixing process in agitated tanks. On the basis of computational fluid dynamics（CFD） software package Fluent 6.2, the mixing characteristics in a tank agitated by dual six-blade-Rushton-turbines（6-DT） are predicted using the detached eddy simulation（DES） method. A sliding mesh（SM） approach is adopted to solve the rotation of the impeller. The simulated flow patterns and liquid velocities in the agitated tank are verified by experimental data in the literature. The simulation results indicate that the DES method can obtain more flow details than Reynolds-averaged Navier-Stokes（RANS） model. Local and global mixing time in the agitated tank is predicted by solving a tracer concentration scalar transport equation. The simulated results show that feeding points have great influence on mixing process and mixing time. Mixing efficiency is the highest for the feeding point at location of midway of the two impellers. Two methods are used to determine global mixing time and get close result. Dimensionless global mixing time remains unchanged with increasing of impeller speed. Parallel, merging and diverging flow pattern form in the agitated tank, respectively, by changing the impeller spacing and clearance of lower impeller from the bottom of the tank. The global mixing time is the shortest for the merging flow, followed by diverging flow, and the longest for parallel flow. The research presents helpful references for design, optimization and scale-up of agitated tanks with multi-impeller.

关键词： agitated tank mixing time computational fluid dynamics(CFD) detached eddy simulation(DES) numerical simulation

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振动混合器内上浮颗粒悬浮特性数值模拟

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排灌机械工程学报 2025年第2期43卷 147-154,162页

作者：李良超赵国柱马国鹭张磊徐斌西南科技大学制造过程测试技术教育部重点实验室四川绵阳621010 中国空气动力研究与发展中心高超声速冲压发动机技术重点实验室四川绵阳621000

对振动混合器内颗粒悬浮特性的深入了解,可为该类混合器的结构设计和优化提供依据.借助计算流体力学技术(computational fluid dynamics,CFD),应用欧拉-欧拉双流体模型对上浮颗粒在振动混合器内的悬浮特性进行了数值模拟研究.振动盘的... 详细信息

对振动混合器内颗粒悬浮特性的深入了解,可为该类混合器的结构设计和优化提供依据.借助计算流体力学技术(computational fluid dynamics,CFD),应用欧拉-欧拉双流体模型对上浮颗粒在振动混合器内的悬浮特性进行了数值模拟研究.振动盘的往复运动采用动网格技术进行处理.通过模拟得到了混合器内的流场和颗粒的动态悬浮特性,并将模拟结果与文献试验数据对比验证模型准确性.结果表明,振动混合器内流场的典型特征为在振动盘的上方和下方各形成一循环涡流,涡流强弱随振动盘往复运动周期变化,但涡流方向保持不变,颗粒在混合器内悬浮分别经历均匀性快速变好、略微变好和动态稳定悬浮3个阶段.提高频率和增大振幅均可以使颗粒更快达到稳定悬浮,且悬浮的均匀性更好,但增大振幅会使悬浮的均匀波动性有所变大.增大固含量可使颗粒悬浮的均匀性增加,波动性减小.

关键词：振动混合器上浮颗粒固液悬浮两相流动数值模拟

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Controlled fabrication and microwave absorbing mechanism of hollow Fe3O4@C microspheres

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Science China Chemistry 2017年第6期60卷 740-747页

作者： Yanhui Hou Huili Yuan Hang Chen Junhai Shen liangchao li Key Laboratory of the Ministry of Education for Advanced Catalysis Materials Department of Chemistry Zhejiang Normal University

Uniform core-shell SiO2@Fe_3O_4@C microspheres were prepared by a one-step hydrothermal method with SiO_2 microspheres as the template, and the hollow Fe_3O_4@C(HFC) microspheres were achieved via etching SiO_2 template. By changing the sizes of SiO_2 microspheres, a series of HFC microspheres with variable cavity sizes were obtained to study the relationship between cavity size and microwave absorbing(MA) performance for the first time. The morphology and structure of samples were characterized in detail. The results showed that the MA performance of HFC sample depended on its cavity size. In particular, the hollow structure was good for improving MA performance and could make MA move to the high-frequency region. More importantly, as the cavity size increases, the resonance frequency of HFC-i(i=1,2, 3, 4) samples moved to a low frequency, and the optimal matching thickness of HFC-i samples was increasing. Among all HFC-i samples, HFC-3 showed the most excellent MA performance,which could be mainly explained by the quarter-wavelength matching model, intrinsical magnetic and dielectric loss. Furthermore,the MA performance of HFC mixture blended by the equal mass fraction of HFC-2, HFC-3 and HFC-4 was the comprehensive results of three HFC-i samples. All the above suggested that the cavity size in HFC sample had a great influence on the MA performance.

关键词： microwave absorbing Fe_3O_4@C cavity size

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Efficient approach and application of the Green's functions in spatial domain in multilayered media

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Science in China(Series F) 2008年第4期51卷 394-407页

作者： ZHANG Min li LeWei li liangchao WU ZhenSen School of Science Xidian University Xi'an 710071 China ECE Department National University of Singapore 10 Kent Ridge Crescent 119620 Singapore

Based on the dipole source method, all components of the Green＇s functions in spectral domain are restructured concisely by four basis functions, and in terms of the two-level discrete complex image method （DCIM） with the high order Sommerfeld identities, an efficient algorithm for closed-form Green＇s functions in spatial domain in multilayered media is presented. This new work enjoys the advantages of the surface wave pole extraction directly carried out by the generalized integral path without troubles of that all components of Green＇s function in spectral domain should be reformed respectively in transmission line network analogy, and then the Green＇s functions for mixed-potential integral equation （MPIE） analysis in both near-field and far-field in multilayered media are obtained. In addition, the curl operator for coupled field in MPIE is avoided conveniently. It is especially applicable and useful to characterize the electromagnetic scattering by, and radiation in the presence of, the electrically large 3-D objects in multilayered media. The numerical results of the S-parameters of a microstrip periodic bandgap （PBG） filter, the radar cross section （RCS） of a large microstrip antenna array, the characteristics of scattering, and radiation from the three-dimensional （3-D） targets in multilayered media are obtained, to demonstrate better effectiveness and accuracy of this technique.

关键词： Green's functions in spatial domain mixed potential integral equation multilayered media discrete complex image method sommerfeld identity

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Enhanced Antibacterial Activities of La/Zn-doped BiNbO4 Nanocomposites

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Chemical Research in Chinese Universities 2017年第6期33卷 917-923页

作者： HOU Yanhui YUAN Huili CHEN Hang DING Yan li liangchao College of Chemistry and life Sciences Zhejiang Normal University Jinhua 321004 P. R. China

Bi1-xLaxNbO4 and Bi1-xZnxNbO4 nanocomposites were prepared by a simple coprecipitation method, and their composition, structure and morphology were characterized by modern testing techniques. The antibacterial activities of the as-prepared samples against Staphylococcus aureus, Escherichia coli and Candida albicans were measured by the experiments of powder inhibition zone, inhibition zone diameter and minimum inhibitory concentration under the irradiation of sunlight. The results show that the antibacterial activities of BiNbO4 doped with La and Zn are superior to that of the parent, and the composition of antibacterial agent and their mass ratio have a great influence on the antibacterial activities. Among these, the antibacterial activity of Bi0.96La0.04NbO4 against three bacteria was best and its antibacterial activity to Candida albicans was better than those to the other two kinds.

关键词： La Zn BiNbO4 Doping Antibacterial activity

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Super-resolution processing of passive millimeter-wave images based on conjugate-gradient algorithm

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Journal of Systems Engineering and Electronics 2009年第4期20卷 762-767页

作者： li liangchao Yang Jianyu Cui Guolong Wu Junjie Jiang Zhengmao Zheng Xin School of Electronic Engineering Univ. of Electronic Science and Technology of China Chengdu 610054 P. R. China

This paper designs a 3 mm radiometer and validate with experiments based on the principle of passive millimeter wave （PMMW） imaging. The poor spatial resolution, which is limited by antenna size, should be improved by post data processing. A conjugate-gradient （CG） algorithm is adopted to circumvent this drawback. Simulation and real data collected in laboratory environment are given, and the results show that the CG algorithm improves the spatial resolution and convergent rate. Further, it can reduce the ringing effects which are caused by regularizing the image restoration. Thus, the CG algorithm is easily implemented for PMMW imaging.

关键词： passive millimeter wave imaging super-resolution conjugate-gradient spectral extrapolation.

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Fabrication of Z-type barium ferrite/silica composites with enhanced microwave absorption

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Science China(Technological Sciences) 2014年第9期57卷 1858-1864页

作者： SHEN JunHai CHEN KeYu li liangchao DING Yan li JuanBi KONG WeiQiu Key Laboratory of the Ministry of Education for Advanced Catalysis Materials Department of Chemistry Zhejiang Normal University

The Z-type barium ferrite/silica composites(Z-BCF/SiO2)were fabricated by in situ chemical synthesis *** composition,structure,morphology and magnetic behavior of the composites were characterized by chemical analysis,IR,XRD,SEM,TEM and *** results indicated that there were some interactions between two components in the Z-BCF/SiO2 composites due to the coating of SiO2 on the Z-BCF *** magnetic properties of the Z-BCF/SiO2 composites were evidently less than that of the Z-BCF,owing to the small volume fraction of magnetic components in the *** to the good transmission and loss properties on electromagnetic waves,the composites were better at microwave absorption than the parent ***,this research laid a foundation for the fabrication of highly efficient microwave absorbing material with enhanced wave impedance matching.

关键词： barium ferrite silica composites microwave absorption performance

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Fabrication, adsorption and photocatalytic properties of ZnTi0.6Fe1.4O4/Carbon nanotubes composites

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Science China Chemistry 2016年第8期59卷 1033-1044页

作者： Jiantao Feng Yanhui Hou Yechen Wang Xiya Wang Haifeng Chen liangchao li College of Chemistry and life Sciences Zhejiang Normal University Jinhua 321004 China

ZnTixFe2-xO4 and ZnTi0.6Fe1.4O4/Carbon nanotubes （ZT0.6F1.4/CNTs） composites were prepared by chemical co-precipitation method. The composition, microstructure, magnetic property, adsorption and photocatalytic activity of the prepared samples were characterized by means of modem analytical techniques. The results indicated that ZT0.6F1.4CNTs composites not only held the original special structure and excellent adsorption properties of CNTs, but also had suitable magnetic property and excellent photocatalytic activity. The removal rate of the samples on Rhodamine B （RhB） depended on the adsorption of CNTs and the photocatalytic degradation of ZTo.6F1.4 in the composites. The maximum adsorption amount （qm） of ZT0.6F1.4/CNTs with the mass ratios of ZT0.6F1.4 to CNTs （mz/c）=l was up to 17.153 mg g-t for RhB, its adsorption behavior was in accord with Langmuir model, and its photocatalytic degradation activity on RhB had a positive correlation with the content of ZT0.6F1.4 in the sample. The experimental results indicate that the total removal rate of composite with rnz/c=l on RhB was more than 95% and the composite had good decontamination capability on industrial dye wastewater. In addition, the samples can be recovered conveniently, activated easily and had good performance for recycling.

关键词： ZnTi0.6Fe1.4O4 ferrite CNTs Rhodamine B adsorption photocatalytic degradation

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Data fusion of radar and IFF for aircraft identification

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Journal of Systems Engineering and Electronics 2012年第5期23卷 715-722页

作者： Yuanquan Tan dianyu Yang liangchao li Jintao Xiong School of Electronic Engineering University of Electronic Science and Technology of China Chengdu 611731 E R. China Sichuan Jiuzhou Electronic Technology Company Mianyang 621000 E R. China

The problem of identification of friend-or-foe aircraft in the actual application condition is addressed.A hybrid algorithm combining fuzzy neutral network with probability factor（FNNP）,multi-level fuzzy comprehensive evaluation and the DempsterShafer（D-S） theory is *** hybrid algorithm constructs a complete process from generating the fuzzy database to the final identification,realizes the identification of friend-or-foe automatically if the training samples or expert’s experience can be obtained,and reduces the effect of uncertainties in the process of *** the same time,the whole algorithm can update the identification result with the augment of *** performance of the proposed algorithm is assessed by *** show that the proposed algorithm can successfully deduce the aircraft’s identity even if the observations have measurement errors.

关键词： fuzzy neutral network with probability factor(FNNP) multi-level fuzzy comprehensive evaluation Dempster-Shafer(D-S) theory identification of friend-or-foe(IFF)

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Controlled fabrication and electrical-magnetic properties of Poly(OT-co-AN)/Ba_(0.8)La_(0.2)Al_2Fe_(10)O_(19) composites

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Science China(Technological Sciences) 2012年第1期55卷 6-15页

作者： CHEN KeYu XU QingQing li liangchao TONG GuoXiu QIAN HaiSheng XIAO QiuShi XU Feng Department of Chemistry Institute of Physical Chemistry Zhejiang Normal University Jinhua 321004 China

Poly（OT-co-AN）/Ba0.8La0.2Al2Fe10O19 （Poly（OT-co-AN）/BLAF） composites were fabricated by in situ polymerization method. It was investigated that of mass rate of momomer （mor/mAN）, polymeration temperature and time, and feeding ratio of BLAF effect on the structures, morphology, conductivity, magnetic property of composites by the orthogonal optimum design. The results indicated that poly （OT-co-AN） copolymer had a better coating on BLAF particles, and there were some interactions between components in the composites. The magnetic properties of the composites were related to content of the magnetic BLAF particles in it. The feeding ratio of BLAF had a significant influence on constitute and conductivity of the composites, followed by the temperature. The reflection loss and the effective bandwidth of composites for electromagnetic wave were at- tributed to the synergistic effect between poly（OT-co-AN） and BLAF. The poly（OT-co-AN）/BLAF composites with mass ratio of BLAF to mix monomer （moT^mAN =1：1） equal to 5/1 at 10 h in 25~C had a maximum synergistic effect between its compo- nents, showed a maximum reflection loss of -26.94 dB at 14.10 GHz and an available bandwidth of 8.54 GHz. It was sug- gested that the composites can be used as a advancing absorption and shielding materials for electromagnetic wave due to their favorable microwave absorption properties.

关键词： poly(OT-co-AN) copolymer Ba-ferrite conductivity magnetic property reflection loss

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