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RISS 인기검색어
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- 저자 : Liu Zhongfu (검색결과 3 건)
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Study on Selective Leakage Protection System of Mine Low-voltage Grid Based on Internet of Things
Liu Zhongfu,Han Guiying,Shi Lixin 보안공학연구지원센터 2015 International Journal of Smart Home Vol.9 No.7
Leakage is one of the most common fault forms of mine low-voltage grid protection. With the continuous increase of automation degree of mine, the leakage protection system of mine low-voltage grid needs to be monitored and managed comprehensively; as a response to this demand, the selective leakage protection system of mine low-voltage grid is explored and studied in this paper from the perspective of practical application based on Internet of Things. In this paper, the design of leakage protection system of mine low-voltage grid is proposed based on the combination of ZigBee protocol the framework of Internet of Things, and the perception layer of Internet of Things is constructed by ZigBee technology to collect and transmit the related data. Meanwhile, the low-voltage leakage fault principle of the mine and the variation law of zero-sequence current and zero-sequence voltage mine are analyzed in this paper; on this basis, a selective leakage protection scheme based on the additional DC power detection and zero-sequence power direction is proposed, in which additional DC power principle is applied to the main feeder switch, the protection principle of zero-sequence power direction is applied to the branch feeder switch, and the branch leakage is interpreted by Fourier algorithm. Through experimental verification, the performance indicators of leakage protection system are consistent with standard requirements, with the small error, which can meet the requirements of the mine grid leakage protection. Internet of Things can realize ZigBee networking and transmit the leakage information of the grid the host computer through ZigBee network.
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Study of a Rapid Detection Method for Protein Content in Milk and Development of Detection Equipment
Liu Zhongfu,Chen Xingwen,Shi Lixin 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.12
Among the nutrients in milk, protein content is a core indicator for measuring the quality of milk. Therefore, to explore a rapid detection method for milk protein content and develop rapid detection equipment for protein ingredient can provide reference for quality analysis and quality control of the production process. In this paper, different dairy protein detection methods are analyzed, the working principles of Micro-Kjeldahl method are studied, and a new type of milk protein content detector is designed based on the Micro-Kjeldahl nitrogen determination method. As for this instrument, LPC2214 microcontroller with ARM structure is taken as the control core, with the functions such as adding certain volume of lye, adding certain volume of boric acid absorption liquid, automatically generating steam required, automatically titrating hydrochloric acid solution, accurately determining the endpoint, conveniently setting parameters and so on, which realizes the digital and intelligent design in determining the protein content in dairy products. Experimental results show that the system is stable, with broad application prospects.
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Robust Design Optimization of Hydrodynamic Characteristics of Airfoil 791
Chenghu ZHANG,Binjuan ZHAO,Zhongfu HUANG,Yanxia FU,Qi LIU,Huilong CHEN 한국유체기계학회 2018 International journal of fluid machinery and syste Vol.11 No.3
In this paper, the influence of the continuous random variation of the flow velocity on hydrodynamic characteristics of airfoil 791 was discussed, and a robust design optimization method was proposed to reduce the influence of uncertain factors on the stability of hydrodynamic performance. Firstly, Bezier curve was used to parameterize the suction side of the airfoil, and its thickness was controlled by four points, which was then taken as the optimization variables. Secondly, the criterion of robustness was given, and then a robust mathematical model was established. Finally, two objective functions of robust optimization were gained on the basis of uncertainty analysis with surrogate model. Combined with multi-objective genetic algorithm, a robust optimal solution with better hydrodynamic characteristics was obtained. The results showed that compared with original case, the thickness near trailing edge altered more smoothly, the resistance and surface wave intensity were obviously decreased, and the maximum reduction of drag-lift ratio and wake unevenness were 6.89% and 25.04% respectively, which contributed to the improvement of wake quality. The change of surface pressure and resistance coefficients were also more stable under the variable inlet flow velocity conditions, and then the robustness was strengthened accordingly. In conclusion, the robust design optimization can obviously improve the hydrodynamic characteristics of the airfoil while reducing the sensitivity to uncertain factors, meanwhile, it can provide better stability during the operating process.
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