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RISS 인기검색어
- 검색키워드
- 저자 : Zhihao Ma (검색결과 4 건)
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Effect of Metallic GPF on the Micro Characteristics of Soot Particles of GDI Engine
Liu Cheng,Ma Zhihao,Yin Zhenlong,Du Weixin,Lv Enyu 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.6
High-resolution transmission electron microscopy (HRTEM) was used to observe the soot particles emitted from gasoline direct injection (GDI) engine equipped with metallic particulate filter (GPF). The changes of microscopic morphology and structure of the soot particles at pre-GPF and post-GPF were studied at a fixed speed of 1500 r/min and 25 %, 50 % 75 % and 100 % load, respectively. Furthermore, the micro-parameters of the primary particles that make up the soot particles were analyzed. The results show that the primary particles are approximately spherical, and agglomerate to form irregular shapes such as chains, branches and rings. The load and GPF have no significant influence on the microscopic morphology of the soot particles, the fractal dimension of soot particles at both ends of the GPF increases with the increase of load. Under the experimental conditions of the engine, most primary particles consisting of the soot particles are “shell-core” structure; The fringe length, tortuosity and interlayer spacing of the primary particles at pre- and post-GPF are monomodal. Among them, the average fringe length increases with the increase of load, while both the average tortuosity and average interlayer spacing change the opposite. These indicated that the degree of graphitization of the soot particle increases with the increasing load. Load and GPF only affect the micro-structure parameters of the primary particles and have no effect on its distribution.
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Influence of Injection System Parameters on Combustion Noise of a Small Power Non-Road Diesel Engine
Zhou Xinfeng,Ma Zhihao,Liu Yuna,Li Ao 한국자동차공학회 2023 International journal of automotive technology Vol.24 No.5
Combustion noise accounts for a large proportion of diesel engine noise. On the premise of not increasing the cost of diesel engine, the injection system parameters such as dynamic fuel supply advance angle and needle valve opening pressure are optimized, and the influence of the above parameters on the in-cylinder pressure, rate of pressure rise, in-cylinder pressure level (CPL) spectrum and high frequency pressure oscillation is analyzed. The study shows that reducing the dynamic fuel supply advance angle can effectively reduce the combustion noise, and appropriately increasing the needle valve opening pressure can also reduce the combustion noise. After the optimization of injection parameters, the combustion noise of the diesel engine with an electronically controlled VE pump-tube-nozzle injection system is significantly reduced compared with the prototype engine, and can reach the same level of combustion noise as the diesel engine with the common rail system without deterioration of fuel economy and emission performance. The experimental study can provide technical reference for diesel engines in the selection of injection system parameters and the optimization of combustion noise in the improvement stage.
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Ammonia etched petroleum pitch-based porous carbon as efficient catalysts for CO2 electroreduction
Ning Hui,Guo Zhihao,Wang Wenhang,Wang Xiaoshan,Yang Zhongxue,Ma Zhengguang,Tian Yangming,Wu Chenghao,Hao Jian,Wu Mingbo 한국탄소학회 2022 Carbon Letters Vol.32 No.3
Electrochemical reduction of carbon dioxide to valuable chemicals is a promising way of storing renewable energy through electric-to-chemical energy conversion, while its large-scale application is in urgent need of cheap and high-performance catalysts. Herein, we invent a convenient method to synthesize N-doped porous carbon by ammonia etching the pyrolysis carbon of petroleum pitch. We found the ammonia etching treatment not only increase the pyridinic-N content, but also enlarge the specific surface area of the petroleum pitch-based porous carbon. As a cheap and easily available catalyst for carbon dioxide electroreduction, up to 82% of Faradaic efficiency towards carbon monoxide was obtained at − 0.9 V vs the reversible hydrogen electrode in 0.1 M KHCO3. After a long time electrocatalysis of more than 20 h, the Faradaic efficiency of carbon monoxide remains 80%, indicating the porous carbon as made have an ultra-high stability as catalyst for carbon dioxide reduction. Our work provides a new technology to economically prepare efficient electrocatalysts for carbon dioxide reduction.
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Zhiqiang Liu,Yinqi Li,Yi Hao,Zhihao Ma,Xianan Gu 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.25 No.3
The research object of this paper is carbon fiber reinforced thermoplastic composite CF/PEEK. Through control planning of robot motion, simulation and experiment on Paving pressure and paving speed are carried out, and on this basis analysis and optimization are carried out. In the analysis of laying pressure, the deformation of rigid press roll and flexible press roll under different pressures is analyzed by finite element simulation. According to the laying experiment, it is certain that the flexible press roll can obtain better laying quality when laying; different pressures are selected to lay the tow. The laying range of these pressures is determined as 50–250 N according to the quality of the tow. In the temperature experiment, the temperature change of the tow in different layers under different laying speeds is analyzed. Through the experiment, it is found that there is a strong correlation between the laying speed and the laying temperature. The experiment also found that under a certain laying speed, selecting the corresponding heating temperature range can obtain higher laying quality and that selecting appropriate paving process parameters, conducting paving tests, and conducting trajectory planning based on the process can effectively reduce paving defects. Finally, in order to solve the problem of path planning for thin-wall structure carbon fiber placement, a natural path algorithm based on Laplace smoothing is proposed. The algorithm obtains the grid surface through the discretization of the thin-walled surface structure, smooths the grid using the Laplace method, and uses the natural path method to obtain the trajectory. At the same time, the algorithm also considers the layout path boundary and layer design, etc. The problem is to complete the trajectory planning through the fiber path assisted generation software and compare the trajectory points with the traditional surface mesh method to verify the rationality of the trajectory algorithm.
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