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Effect of methane-hydrogen mixtures on flow and combustion of coherent jets

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Journal of Iron and Steel Research International 2017年第11期24卷 1143-1151页

作者： Ting Cheng Rong Zhu kai dong School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China Beijing Key Laboratory of Research Center of Special Melting and Preparation of High-end Metal Materials University of Science and Technology BeijingBeijing 100083China

Coherent jets are widely used in electric are furnace （EAF） steelmaking to increase the oxygen utilization and chemical reaction rates. However, the influence of fuel gas combustion on jet behavior is not fully understood yet. The flow and combustion characteristics of a coherent jet were thus investigated at steelmaking temperature using Fluent software, and a detailed chemical kinetic reaction mecha- nism was used in the combustion reaction model. The axial velocity and total temperature of the supersonic jet were measured via hot state experiments. The simulation results were compared with the experimental data and the empirical jet model proposed by Ito and Muchi and good consistency was obtained. The research results indicated that the potential core length of the coherent jet can be prolonged by optimizing the combustion effect of the fuel gas. Besides, the behavior of the supersonic jet in the subsonic section was also investigated, as it is an important factor for controlling the position of the oxygen lance. The investigation indicated that the attenuation of the coherent jet is more notable than that of the conventional jet in the subsonic section.

关键词： Supersonic jet Numerical simulation Mixed fuel gas Flow field Combustion characteristic

High throughput bandwidth optimized VLSI design for motion compensation in AVS HDTV decoder

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第6期9卷 822-832页

作者： kai LUO dong-xiao LI Ming ZHANG Department of lnformation Science and Electronic Engineering Zhejiang University Hangzhou 310027 China

In this paper we present a motion compensation (MC) design for the newest Audio Video coding Standard (AVS) of China. Because of compression-efficient techniques of variable block size (VBS) and sub-pixel interpolation, intensive pixel calculation and huge memory access are required. We propose a parallel serial filtering mixed luma interpolation data flow and a three-stage multiplication free chroma interpolation scheme. Compared to the conventional designs, the integrated architecture supports about 2.7 times filtering throughput. The proposed MC design utilizes Vertical Z processing order for reference data re-use and saves up to 30% memory bandwidth. The whole design requires 44.3k gates when synthesized at 108 MHz clock frequency using 0.18-μm CMOS technology and can support up to 1920×1088@30 fps AVS HDTV video decoding.

关键词： Audio Video coding Standard (AVS) Motion compensation (MC) Interpolation VLSI Architecture

Simulation of three-phase flow and lance height effect on the cavity shape

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International Journal of Minerals,Metallurgy and Materials 2014年第6期21卷 523-530页

作者： kai dong Rong Zhu Wei Gao Fu-hai Liu School of Mechanical Engineering University of Science and Technology Beijing School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing Shougang Design Institute

A three-dimensional computational fluid dynamics （CFD） model was developed to simulate a 150-t top-blown converter. The ef-fect of different lance heights on the cavity shape was investigated using the volume of fluid （VOF） method. Numerical simulation results can reflect the actual molten bath surface waves impinged by the supersonic oxygen jets. With increasing lance height, the cavity depth de-creases, and the cavity area, varying like a parabola, increases and then decreases. The cavity area maximizes at the lance height of 1.3 m. Under the three different lance heights simulated in this study, all of the largest impact velocities at the molten bath surface are between 50 m/s and 100 m/s.

关键词： metallurgical furnaces basic oxygen converters lance height cavity shape computational fluid dynamics computer simulation

Fundamental diagrams for pedestrian flows in a channel via an extended social force model

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Journal of Hydrodynamics 2018年第5期30卷 950-957页

作者： Yan-fang Wei dong-kai Lan Li-yun dong Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China College of Physical Science and Technology Yulin Normal University Yulin 537000 China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai 200072 China

In this paper, an extended social force model was applied to investigate fundamental diagrams of pedestrian flows. In the presented model, both the static floor field and the view field were taken into account. Then each pedestrian can determine his/her desired walking directions according to both global and local information. The fundamental diagrams were obtained numerically under periodic boundary condition. It was found that the fundamental diagrams show good agreement with the measured data in the case of unidirectional flow, especially in the medium density range. However, the fundamental diagram for the case of bidirectional flow gave larger values than the measured data. Furthermore, the bidirectional flux is larger than the tmidirectional flux in a certain density range. It is indicated that the bidirectional flow may be more efficient than the unidirectional flow in some cases. The process of lane formation is quite quick in the model. Typical flow patterns in three scenarios were given to show some realistic applications.

关键词： Pedestrian flow social force model view field floor field fundamental diagram

A review of carbon dioxide disposal technology in the converter steelmaking process

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International Journal of Minerals,Metallurgy and Materials 2020年第11期27卷 1421-1429页

作者： Rong Zhu Bao-chen Han kai dong Guang-sheng Wei School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China Beijing Key Laboratory of Research Center of Special Melting and Preparation of High-end Metal Materials University of Science and Technology BeijingBeijing 100083China

In last decade,the utilization of CO?resources in steelmaking has achieved certain metallurgical effects and the technology is *** this review,we summarized the basic reaction theory of CO2,the CO2 conversion,and the change of energy-consumption when CO2 was introduced in converter steelmaking *** the CO2-O2 mixed injection(COMI)process,the CO2 conversion ratio can be obtained as high as 80%or more with a control of the CO2 ratio in mixture gas and the flow rate of CO2,and the energy is saving and even the energy consumption can be reduced by 145.65 MJ/t under certain *** addition,a complete route of CO2 disposal technology is proposed combining the comparatively mature technologies of CO2 capture,CO2 compression,and liquid CO2 storage to improve the technology of CO2 *** results are expected to form a large-scale,highly efficient,and valuable method to dispose of CO2.

关键词： CO2 utilization carbon dioxide steelmaking enhanced stirring temperature control

Microstructure and properties of ultrafine WC-Co-VC cemented carbides with different Co contents

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Rare Metals 2022年第6期41卷 1955-1960页

作者： kai-HuaShi Ke-Chao Zhou Zhi-You Li Xiu-Qi Zan kai-Lin dong Qing Jiang State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Precision Parts Department Zigong Cemented Carbide Corporation LimitedZigong 643011China

Ultrafine WC-Co-VC cemented carbides are used extensively in a variety of industrial environments due to their excellent mechanical properties and outstanding wear *** content affects the service performance of the cemented *** the present study,the influ-ences of Co content on microstructure,physical,and mechanical properties were investigated *** WC-Co-VC cemented carbides with Co content varying from 4 wt%and 7 wt%and assistance of VC(0.35 wt%)as inhibitor of WC grain growth were *** physical and mechanical properties were tested and the microstructure characteristics were observed by optical microscope(OM)and scanning electron microscopy(SEM).From the results,it is found that with Co content increasing,both the cobalt magnetism and bending strength increase,while the coercive force,Rockwell hardness,density,and abrasive wear resistance *** addition,the OM and SEM results show that the increase of Co content in WC-Co-VC cemented carbides tends to reduce the quantity and size of micro-pores,and make the fracture mode change from brittle fracture to ductile fracture.

关键词： Ultrafine Cemented carbide Co content Microstructure Properties

AocML： A Domain-Specific Language for Model-Driven Development of Activity-Oriented Context-Aware Applications

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Journal of Computer Science & Technology 2018年第5期33卷 900-917页

作者： Xuan-Song Li Xian-Ping Tao Wei Song kai dong School of Computer Science and Engineering Nanjing University of Science and Technology Nanfing 210093 China State Key Laboratory for Novel Software Technology Nanjing University Nanjing 210023 China School of Computer Science and Engineering Southeast University Nanjing 211189 China

Activity-oriented context-aware （AOCA） applications are representative in pervasive computing. These appli- cations recognize daily-life human activities, perceive the environment status related to the activities, and react to ensure the smooth performance of the activities. Existing research proposed a specific light-weight, incremental method to support the development of such applications; however it is not easy to learn and use. This paper aims to facilitate the development of such applications and improve the productivity of developers. We propose AocML, a textual domain-specific language which provides a high-level abstraction of AOCA applications. Specifically, we first show the software model of AOCA applications and the abstract syntax of AocML. Then, we introduce the concrete syntax of AocML. We also implement the tools for AocML, including the development environment as well as the generation of Java code and ontology specification. Moreover, we use a case study and evaluation to demonstrate the advantages of AocML.

关键词： pervasive computing context-awareness model-driven development domain-specific language

CBSC: A Crowdsensing System for Automatic Calibrating of Barometers

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Journal of Computer Science & Technology 2019年第5期34卷 1007-1019页

作者： Hai-Bo Ye Xuan-Song Li Li Sheng kai dong College of Computer Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 211100China School of Computer Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China School of Computer Science and Engineering Southeast UniversityNanjing 211189China

The mobile crowdsensing software systems can complete large-scale and complex sensing tasks with the help of the collective intelligence from large numbers of ordinary users. In this paper, we build a typical crowdsensing system, which can efficiently calibrate large numbers of smartphone barometer sensors. The barometer sensor now becomes a very common sensor on smartphones. It is very useful in many applications, such as positioning, environment sensing and activity detection. Unfortunately, most smartphone barometers today are not accurate enough, and it is rather challenging to efficiently calibrate a large number of smartphone barometers. Here, we try to achieve this goal by designing a crowdsensingbased smartphone calibration system, which is called CBSC. It makes use of low-power barometers on smartphones and needs few reference points and little human assistant. We propose a hidden Markov model for peer-to-peer calibration, and calibrate all the barometers by solving a minimum dominating set problem. The field studies show that CBSC can get an accuracy of within 0.1 hPa in 84% cases. Compared with the traditional solutions, CBSC is more practical and the accuracy is satisfying. The experience gained when building this system can also help the development of other crowdsensing-based systems.

关键词： crowdsensing system smartphone sensing barometer calibration

Modeling of an Impinging Oxygen Jet on Molten Bath Surface in 150t EAF

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Journal of Iron and Steel Research International 2011年第9期18卷 13-20页

作者： HE Chun-lai ZHU Rong dong kai QIU Yong-quan SUN kai-ming Metallurgical and Ecological Engineering School University of Science and Technology Beijing Beijing 100083 China Tianjin Pipe (Group) Corporation Tianjin 300301 China

A transient three-dimensional mathematical model has been developed to analyze the three-phase flow in a 150 t EAF （electric arc furnace） using oxygen. VOF （multiphase volume of fluid） method is used to simulate the behaviors of molten steel and slag. Numerical simulation was conducted to clarify the transient phenomena of oxygen impingement on molten bath. When oxygen jet impinges on the surface of molten bath, the slag layer is broken and the penetrated cavity in molten steel is created. Simultaneously, the wave is formed at the surface of uncovered steel on which the slag layer is pushed away by jet. The result of numerical simulations shows that the area and velocity of uncovered steel created by impingement, jet penetration depth change from 0. 10 m2 , 0. 012 5 m/s, 3.58 cm to 0.72 m2 , 0. 1445 m/s, 11.21 cm, when the flow rate of an oxygen lance varies from 500 to 2000 m3/h. The results have been validated against water model experiments. More specially, the relation between the penetration depth and oxygen flow rate predicted by numerical simulation has been found to agree well with that concluded by water model.

关键词： electric arc furnace three-phase flow numerical simulation