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Effect of magnesia on the compressive strength of pellets

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International Journal of Minerals,Metallurgy and Materials 2014年第5期21卷 431-437页

作者： Feng-man Shen Qiang-jian Gao Xin Jiang Guo Wei hai-yan Zheng School of Materials and Metallurgy Northeastern University

The compressive strength of MgO-fluxed pellets was investigated before and after they were reduced. The porosity and pore size of green pellets, product pellets, and reduced pellets were analyzed to clarify how MgO affects the strength of the pellets. Experimental resuits show that when the MgO-bearing flux content in the pellets increases from 0.0wt% to 2.0wt%, the compressive strength of the pellets at ambient temperature decreases, but the compressive strength of the pellets after reduction increases. Therefore, the compressive strength of the pellets after reduction exhibits no certain positive correlation with that before reduction. The porosity and pore size of all the pellets （with different MgO contents） increase when the pellets are reduced. However, the increase in porosity of the MgO-fluxed pellets is relatively smaller than that of the traditional non-MgO-fluxed pellets, and the pore size range of the MgO-fluxed pellets is relatively narrower. The reduction swelling index （RSI） is a key factor for governing the compressive strength of the reduced pellets. An approximately reversed linear relation can be concluded that the lower the RSI, the greater the compressive strength of the reduced pellets is.

关键词： iron ore pellets compressive strength magnesia ore reduction swelling

Expediting^(*)OH accumulation kinetics on metal-organic frameworks-derived CoOOH with CeO_(2) “accelerator” for electrocatalytic 5-hydroxymethylfurfural oxidation valorization

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Journal of Energy Chemistry 2024年第11期98卷 721-732页

作者： Peiyun Zhou Haokun Pan Guangtong hai Xiang Liu Xiubing Huang ge Wang Beijing Advanced Innovation Center for Materials genome Engineering Beijing Key Laboratory of Function Materials for Molecule&Structure ConstructionSchool of Materials Science and EngineeringUniversity of Science and Technology BeijingBeijing 100083China Department of Chemistry Tsinghua UniversityBeijing 100084China Institute of Zhejiang University-Quzhou Zhejiang UniversityQuzhou 324000ZhejiangChina

In this work,nickel foam supported CeO_(2)-modified CoBDC(BDC stands for terephthalic acid linker)metal-organic frameworks(NF/CoBDC@CeO_(2)) are prepared by hydrothermal and subsequent impregnation methods,which can be further transformed to NF/CoOOH@CeO_(2) by reconstruction during the electrocatalytic *** obtained NF/CoOOH@CeO_(2) exhibits excellent performance in electrocatalytic oxidation of 5-hydroxymethylfurfural(HMF) because the introduction of CeO_(2) can optimize the electronic structure of the heterointerface and accelerate the accumulation of ^(*)*** requires only a potential of 1.290 V_(RHE) to provide a current density of 50 mA cm^(-2) in 1.0 M KOH+50 mM HMF,which is 222 mV lower than that required in 1,0 M KOH(1.512 V_(RHE)).In addition,density-functional theory calculation results demonstrate that CeO_(2) biases the electrons to the CoOOH side at the heterointerface and promotes the adsorption of ^(*)OH and ^(*)HMF on the catalyst surface,which lower the reaction energy barrier and facilitate the electrocata lytic oxidation process.

关键词： CeO_(2) Metal-organic frameworks 5-Hydroxymethylfurfural oxidation reaction Heterointerface Reconstruction

Simulation of vortex shedding behind a bluff body flame stabilizer using a hybrid U-RANS/PDF method

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Acta Mechanica Sinica 2012年第2期28卷 348-358页

作者： Min-Ming Zhu Ping-Hui Zhao hai-Wen ge Yi-Liang Chen Department of Thermal Science and Energy Engineering University of Science and Technology of China230027 HefeiChina Engine Research Center University of Wisconsin-Madison1500 Engineering DriveMadisonWI 53706USA

The present study aims at the investigation of the effects of turbulence-chemistry interaction on combus- tion instabilities using a probability density function （PDF） method. The instantaneous quantities in the flow field were decomposed into the Favre-averaged variables and the stochastic fluctuations, which were calculated by unsteady Reynolds averaged Navier-Stokes （U-RANS） equations and the PDF model, respectively. A joint fluctuating velocity- frequency-composition PDF was used. The governing equa- tions are solved by a consistent hybrid finite volume/Monte- Carlo algorithm on triangular unstructured meshes. A non- reacting flow behind a triangular-shaped bluff body flame stabilizer in a rectilinear combustor was simulated by the present method. The results demonstrate the capability of the present method to capture the large-scale coherent struc- tures. The triple decomposition was performed, by divid- ing the coherent Favre-averaged velocity into time-averaged value and periodical coherent part, to analyze the coherent and incoherent contributions to Reynolds stresses. A sim- ple modification to the coefficients in the turbulent frequency model will help to improve the simulation results. Unsteady flow fields were depicted by streamlines and vorticity con- tours. Moreover, the association between turbulence produc- tion and vorticity saddle points is illustrated.

关键词： Vortex shedding PDF method Unsteady RANS Finite volume. Bluff bodies

Gas-solid reduction kinetic model of MgO-fluxed pellets

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International Journal of Minerals,Metallurgy and Materials 2014年第1期21卷 12-17页

作者： Qiang-jian Gao Feng-man Shen Xin Jiang Guo Wei hai-yan Zheng School of Materials and Metallurgy Northeastern University

The reduction process of MgO-fluxed pellets was investigated and compared with traditional acidic pellets in this paper. Based on the piston flow concept and experimental data, a kinetic model fitting for the gas-solid phase reduction of pellets in tubular reactors （blast furnace, BF） was built up, and the equations of reduction reaction rate were given for pellets. A series of reduction experiments of pellets were carried out to verify the model. As a result, the experimental data and calculated result were fitted well. Therefore, this model can well describe the gas-solid phase reduction process and calculate the reduction reaction rate of pellets. Besides, it can give a better explanation that the reduction reaction rate （reducibility） of MgO-fluxed pellets is better than that of traditional acidic pellets in BF.

关键词： ore pellets magnesia reduction kinetics blast furnaces

Characterization of suspended solids and particle-bound heavy metals in a first flush of highway runoff

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第11期9卷 1567-1575页

作者： Fa-hui NIE Tian LI hai-feng YAO man FENG Guang-kai ZHANG State Key Laboratory of Pollution Control and Resource Reuse Tongji University Shanghai 200092 China Institute of Environment Engineering Research East China Jiaotong University Nanchang 330013 China

To investigate the dynamic characteristics of total suspended solids (TSS) and their particle-bound heavy metals in a first flush, the runoff sampling together with its flow rate measuring was conducted for three rainfall events at outfalls of highway in Shanghai from June to September 2007. Field samples were analyzed to determine the concentrations of TSS and particle-bound heavy metals, such as Zn, Pb, and Cu. Results show that the wash off behavior of TSS under varying runoff rate condition can be explained by different antecedent dry weather period (ADWP). Contribution of fine fraction (generally higher than that of coarse fraction (>45 μm). When the runoff flow increased obviously, a significant contribution of the coarse fraction was observed for a certain rainfall events with long antecedent dry weather condition. The changes of total metals concentration and particle-bound metal concentrations were strongly dependent on the TSS variation. TSS was generally well correlated with most particulate-bound heavy metals. Of the heavy metals, the concentration of Zn was found considerably high and that of Pb was significantly low at North Zhongshan 2 Road, in Shanghai, China, but they are still within the range reported in the literature. Fluctuation of heavy metal contents in the coarse fraction during a first flush period was more significant compared with that in the fine fraction. The results will assist in the development of effective control strategies to minimize heavy metals and solids in highway runoff.

关键词： Heavy metals Highway runoff First flush Suspended solids (SS)

Mechanical Design and Dynamic Compliance Control of Lightweight manipulator

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International Journal of Automation and computing 2021年第6期18卷 926-934页

作者： Shao-Lin Zhang Yue-Guang ge hai-Tao Wang Shuo Wang State Key Laboratory of management and Control for Complex Systems Institute of AutomationChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

In the existing modular joint design and control methods of collaborative robots, the inertia of the manipulator link is large,the dynamic trajectory planning ability is weak, the collision stop safety strategy is dependent, and the adaptability and safety to the changing environment are limited. This paper develops a six-degree-of-freedom lightweight collaborative manipulator with real-time dynamic trajectory planning and active compliance control. Firstly, a novel motor installation, joint transmission, and link design method is put forward to reduce the inertia of the links and improve intrinsic safety. At the same time, to enhance the dynamic operation capability and quick response of the manipulator, a smooth planning of position and orientation under initial/end pose and velocity constraints is proposed. The adaptability to the environment is improved by the active compliance control. Finally, experiments are carried out to verify the effectiveness of the proposed design, planning, and control methods.

关键词： Lightweight manipulator mechanical design dynamic trajectory planning compliance control robot control

Clinical application of ultrasound-guided selective proximal and distal brachial plexus block in rapid rehabilitation surgery for hand trauma

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World Journal of Clinical Cases 2020年第11期8卷 2137-2143页

作者： Jin Zhang man Li hai-Bin Jia Lan Zhang Department of Anesthesiology Sichuan Orthopedic HospitalChengdu 610041Sichuan ProvinceChina

BACKGROUND Anesthesia plays an essential role in the successful surgical procedures for hand *** with general anesthesia,brachial plexus block shows lots of benefits for the upper ***,ultrasound-guided selective proximal and distal brachial plexus block may overcome the issues of incomplete block and failure of anesthesia in such *** present study assessed the efficacy of ultrasound-guided selective proximal and distal brachial plexus block in clinical *** To explore the efficacy of ultrasound-guided selective proximal and distal brachial plexus block in rapid recovery surgery for hand *** A total of 68 patients with traumatic hand injuries treated at our hospital from January 2018 to June 2019 were *** were divided into an observation group and a control group with 34 patients in each *** observation group underwent selective brachial plexus block guided by ultrasound and the control group underwent conventional brachial plexus *** analgesic efficacy,intraoperative complications,wound healing time,and length of hospital stay were compared between the two groups under different *** The percentage of cases with analgesia graded as“excellent or very good”was higher in the observation group than in the control group(Pgesic efficacy in patients with traumatic hand *** can reduce the incidence of intraoperative complications,promote wound healing,and shorten the length of hospital stay.

关键词： Selective brachial plexus block Ultrasound Hand trauma Rapid rehabilitation surgery

Force chains based mesoscale simulation on the dynamic response of Al-PTFE granular composites

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Defence Technology（防务技术） 2021年第1期17卷 56-63页

作者： Le Tang Chao ge Huan-guo Guo Qing-bo Yu hai-fu Wang Beijing Institute of Technology China

Force chains based mesoscale simulation is conducted to investigate the response behavior of aluminumpolytetrafluoroethylene(Al-PTFE)granular composites under a low-velocity impact.A two-dimensional model followed the randomly normal distribution of real Al particles size is *** dynamic compressive process of Al-PTFE composites with varied Al mass fraction is simulated and validated against the *** results indicate that,force chains behavior governed by the number and the size of agglomerated Al particles,significantly affects the impact response of the *** failure mode of the material evolves from shear failure of matrix to debonding failure of particles with increasing density.A high crack area of the material is critical mechanism to arouse the initiation *** damage maintained by force chains during large plastic strain builds up more local stresses concentration to enhance a possible reaction *** addition,simulation is performed with identical mass fraction but various Al size distribution to explore the effects of size centralization and dispersion on the mechanical properties of *** is found that smaller sized Al particle of composites are more preferred than its bulky material in ultimate *** dispersed degree is facilitated to create stable force chains in samples with comparable particle *** simulation studies provide further insights into the plastic deformation,failure mechanism,and possible energy release capacity for Al-PTFE composites,which is helpful for further design and application of reactive materials.

关键词： Al-PTFE Granular composites Mesoscale simulation Dynamic response Force chains

Three-segment control theory of MgO/Al2O3 ratio based on viscosity experiments and phase diagram analyses at 1500℃

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Journal of Iron and Steel Research International 2020年第6期27卷 624-630页

作者： Xin Jiang Huai-yu Zhang hai-yan Zheng Qiang-jian Gao Feng-man Shen School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina

In recent years, more and more high Al2O3 iron ores were used in East Asia, especially in China, which increased the Al2O3 content in blast furnace (BF) slag and resulted in poor metallurgical properties of slag. Adding MgO-bearing flux is one of the methods to improve the metallurgical properties of slag with high Al2O3. However, there is lack of theoretical basis for the proper MgO/Al2O3 ratio. Therefore, the properties of slag in SiO2-CaO-MgO-Al2O3 system were investigated based on viscosity experiments and phase diagram analyses at 1500℃, and the proper MgO/Al2O3 ratio was explored according to the Al2O3 content in slag. The experimental results show that: (1) in the case of Al2O3 content less than 14mass%, there is no limitation of the MgO/Al2O3 ratio, and the amount of MgO in slag can be determined according to the hearth tempera-ture and desulfurization;(2) in the case of Al2O3 content between 15 and 17mass%, the proper MgO/Al2O3 ratio should be 0.40-0.50;(3) in the case of Al2O3 content between 18 and 20mass%, the proper MgO/Al2O3 ratio should be 0.45-0.55. Consequently, the three-segment control theory of MgO/Al2O3 for BF slag was built, and the actual BF performances proved the validity and applicability of this theory. The research contents and results can give theoretical guidelines for stable BF operation in a wide range of Al2O3 content of 12-20mass%.

关键词： MgO/Al2O3 ratio Blast furnace slag Viscosity Ironmaking Phase diagram