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Numerical and experimental study on coke size distribution in bell-type charging in the CDQ shaft

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Journal of University of Science and Technology Beijing 2008年第3期15卷 236-240页

作者： Zhicheng Liu Yanhui Feng Xinxin Zhang Lie Xu Zhendong Yu school of mechanical engineering University of Science and Technology Beijing Beijing 100083 China Anshan Coking and Refractory engineering Consulting Corp. Anshan 114002 China

The mechanism of coke size segregation in the radial direction of pre-chamber in coke dry quenching （CDQ） shaft was investigated by experiment and numerical analysis. The experimental apparatus was a cold three-dimensional semicircle model for bell-type charging, which was used to study the influences of different kinds of bells and different stock line levels on the radial distribution of coke size in the radial direction of a pre-chamber. A mathematical model was used, which is capable of estimating the radial average size distribution as well as the radial deposit distribution of each particle size for multiple size coke with a few fixed parameters. The calculated results agree well with the experimental data, which proves the reliability of both experimental study and numerical analysis.

关键词： coke size distribution coke dry quenching (CDQ) size segregation charging

Surface characterization of steel/steel contact lubricated by PA06 with novel black phosphorus nanocomposites

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Friction 2021年第4期9卷 723-733页

作者： Zhiheng LUO Jingyuan YU Yufu XU He XI Gang CHENG Lulu YAO Ruhong SONG Karl D DEARN Institute of Tribology School of Mechanical EngineeringHefei University of TechnologyHefei 230009China school of Chemistry and Chemical engineering Hefei University of TechnologyHefei 230009China Mason Institute of Tribology School of Engineering University of BirminghamEdgbastonBirmingham B152TTUnited Kingdom

In the present work,two types of novel nano additives,titanium sulfonate ligand/black phosphorus(TiLi/BP)and titanium dioxide/black phosphorus(TiCVBP)nanocomposites,were *** tribological behavior of the steel/steel friction pairs lubricated by polyalphaolefins type 6(PA06)containing the nanocomposites under boundary lubrication was *** worn surfaces were analyzed using modem surface *** experimental results show that the rubbed surfaces became smooth and showed little wear with the addition of the ***_(2)/BP nanocomposites can significantly improve the lubricity of BP nanosheets under high contact *** synergistic roles of the load-bearing abilities and rolling effect of TiO_(2) nanoparticles,the slip induced by the BP with its layered structure,and the establishment of a tribofilm on the sliding interface are the basis of the tribological mechanisms.

关键词： surface characterization black phosphorus(BP)nanosheets nano titanium dioxide boundary lubrication steel/steel contact

Nonlinear Spline Finite Element Method for Ribbing of Cold-Rolled Coils

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Journal of Iron and Steel Research International 2012年第1期19卷 36-40页

作者： QIN Jian ZHANG Qing-dong HUANG Ke-fu mechanical engineering school University of Science and Technology Beijing Beijing 100083 China College of engineering Peking University Beijing 100871 China

The ribbing problem has serious influence on the steel product quality, which produces additional shape waves on the surface of uncoiled steel strip on the process of curl. Nonlinear spline finite element method （n-spline FEM） is adopted to establish the relationship between the ribbing height and deflection of additional shape wave, for example, post buckling deformation. The proposed spline FEM is more effective and convenient than traditional finite element method in the buckling analysis. Using the spline FEM, the shape wave caused by the ribbing is calculated, and then the ribbing values can be obtained which are difficult to measure in practice. At the same time, the judgment rule is also given for estimating the strip quality according to the ribbing value.

关键词： steel strip ribbing nonlinear spline FEM post-buckling

Highly degradable chitosan-montmorillonite (MMT) nanocomposite hydrogel for controlled fertilizer release

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Frontiers of Environmental Science & engineering 2023年第5期17卷 1-11页

作者： Zeou Dou Maria Vitoria Bini Farias Wensi Chen Dongjing He Yuhang Hu Xing Xie school of Civil and Environmental engineering Georgia Institute of TechnologyAtlantaGA 30332USA George W.Woodruff school of mechanical engineering Georgia Institute of TechnologyAtlantaGA 30332USA school of Chemical and Biomolecular engineering Georgia Institute of TechnologyAtlantaGA 30332USA

Fertilizer consumption is increasing drastically along with the rapid expansion of farming in response to the ever-growing population. However, a significant portion of the nutrients in traditional fertilizers is lost during leaching and runoff causing economic loss and environmental threats. Polymer-modified controlled-release fertilizers provide an opportunity for mitigating adverse environmental effects and increasing the profitability of crop production. Here, we present a cheap and easy-to-fabricate controlled-release fertilizer excipient based on hydrogels scaffolded by safe and biodegradable chitosan and montmorillonite (MMT) nanoclays. By introducing elastic and flexible physical crosslinking induced by 2-dimensional (2D) MMT nanoflakes into the chitosan hydrogel, highly swellable and degradable chitosan-MMT nanocomposites were fabricated. The addition of MMT into the chitosan hydrogels enhanced the total release of phosphorous (P) and potassium (K), from 22.0 % to 94.9 % and 9.6% to 31.4 %, respectively, compared to the pure chitosan gel. The chitosan-MMT nanocomposite hydrogel achieved a well-controlled overall fertilizer release in soil. A total of 55.3 % of loaded fertilizer was released over 15 d with a daily release of 2.8 %. For the traditional fertilizer podwer, 89.2 % of the fertilizer was washed out during the first irrigation under the same setup. In the meantime, the nanocomposites improved the water retention of the soil, thanks to its excellent water absorbency. Moreover, the chitosan-MMT nanocomposite hydrogels exhibited high degradation of 57 % after swelling in water for 20 d. Such highly degradable fertilizer excipient poses minimal threat to the long-term fertility of the soil. The engineered Chitosan-MMT biopolymer scaffold as a controlled-release fertilizer excipient provides a promising opportunity for advancing sustainable agriculture.

关键词： Biopolymer Hydrogel Controlled-release fertilizer Nanoclay Nanocomposite

Aquatic unmanned aerial vehicles(AquaUAV):Bionic prototypes,key technologies,analysis methods,and potential solutions

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Science China(Technological Sciences) 2023年第8期66卷 2308-2331页

作者： WANG XinYang YANG XingBang ZHAO JiaWei PEI Xuan SU HaoHong WANG TianMiao HOU TaoGang school of Electronic and Information engineering Beijing Jiaotong UniversityBeijing 100044China school of mechanical engineering and Automation Beihang UniversityBeijing 100083China school of Biological Science and Medical engineering Beijing Advanced Innovation Centre for Biomedical EngineeringKey Laboratory for Biomechanics and Mechanobiology of Ministry of EducationBeihang UniversityBeijing 100083China

Some research on aircraft is largely inspired by *** them,aerial-aquatic amphibians with trans-media locomotion capabilities have greatly promoted the development of aquatic unmanned aerial vehicles(Aqua UAV).In this article,the studies of Aqua UAV are sorted out by their biological counterpart and summarized in chronological order from 2005 to *** further understand the key technologies of Aqua UAV,we focus on the structural compatibility design of wing and aerial-aquatic propulsion methods by analyzing their advantages and *** addition,the analysis methods of kinematics and dynamics performance of Aqua UAV for simulation and experiment are involved in the process of studying the kinematics,lift/drag,and propulsion of ***,we present several challenges and propose some potential solutions to improve the ability of Aqua UAV in the future.

关键词： aquatic unmanned aerial vehicle(AquaUAV) variable wing design propulsion system computer simulation

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The Experimental Study on Regenerative Heat Transfer in High Temperature Air Combustion

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Journal of Thermal Science 2004年第4期13卷 366-370页

作者： Li JIA Jianshu LI Department of Power engineering School of MechanicalElectronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Beijing Institute of Civil engineering&Architecture Beijing 100044China

For the purpose of decomposing the processing gases CF4 from semiconductor manufacturers, ceramic honeycomb regenerative burner system is suggested by using the principle of HTAC. A simulated high temperature air combustion furnace has been used to determine the features of HTAC flames and the results of the decomposition of CF4. The preheat air temperature of it is above 900℃. The exhaust gas released into the atmosphere is lower than 150℃. Moreover, the efficiency of recovery of waste heat is higher than 80%, the NOx level in exhaust gas is less than 198 mg/m3 and the distribution of temperature in the furnace is nearly uniform. The factors influencing on heat transfer, temperature profile in chamber and NOX emission were discussed. Also some CF4 can be decomposed in this system.

关键词： generator heat transfer high temperature air combustion NOX emission.

Investigation on Drag Reduction of Trucks

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Journal of Shanghai Jiaotong university(Science) 2008年第2期13卷 201-205页

作者：齐晓霓刘震炎 Center for Combustion and Environmental Technology School of Mechanical and Power EngineeringShanghai Jiaotong University

A study of the mechanism of fences was given to reduce drag by means of theoretical analysis, numerical simulation and experimental research.A 3D mathematical model has been developed based on com- putational fluid dynamics software Phoenics that was capable of handling steady state,3D flow to simulate the flow field around the *** experiment made in a low speed wind tunnel is used as references for *** analyzing the results of calculation and experiment,the flowing mechanism of the flow field around the container truck and the drag-reducing mechanism of #-shaped fences on the truck are unveiled, which provides theoretical guidance to the aerodynamic formation designing and amelioration.

关键词： drag reduction truck fence

Traffic System Reliability Comparison Between Digital Driving and Conventional Driving

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Journal of Beijing Institute of Technology 2009年第4期18卷 412-415页

作者：王武宏沈中杰刘皓姚丽亚池内克史 school of mechanical engineering Beijing Institute of Technology Computer Vision Laboratory The University of Tokyo

Driver behavior modeling is becoming increasingly important in the study of traffic safety and devel- opment of cognitive vehicles. An algorithm for dealing with reliability for both digital driving and conventional driving has been developed in this paper. Problems of digital driving error classification, digital driving error probability quantification and digital driving reliability simulation have been addressed using a comparison re- search method. Simulation results show that driving reliability analysis discussed here is capable of identifying digital driving behavior characteristics and achieving safety assessment of intelligent transportation system.

关键词： driving behavior digital driving characteristics cognitive vehicle intelligent transportation system

Characteristics of Vibration Induced by Cavitation

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Journal of Beijing Institute of Technology 2005年第4期14卷 411-415页

作者：王国玉陶磊刘淑艳钱建军 school of mechanical and Vehicular engineering Beijing Institute of Technology Beijing100081 China

Cavitation-induced vibration characteristics and the relations between the vibration and cavitation are studied. Cavitation vibrations are measured around a model hollow-jet valve by an aceelerometer under cavitating and non-cavitating conditions. The measurement data is analyzed by FFT method, The corresponding cavitating flow patterns are photographed by a high speed camera with an xenon flash lamp. The frequency band of the vibration induced by cavitation is determined, To compare the vibration intensities under different cavi ration conditions, a definition of vibration acceleration level is introduced based on power spectral density of the vibration. By the analysis of vibration, the definitions of characteristic cavitation number are suggested. Ac cording to these cavitation numbers, the cavitation process is divided into three stages, that is, incipient cavitation, subcavitation and supercavitation.

关键词： cavitation vibration flow patterns