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Heat transfer characteristics of single-ring closed PHP
Lipeng Wang,Yue Cai,Qianqian Zhang,Sheng Shi,Lin Wu,Hongren Zhan 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.4
In order to solve the problem of heat dissipation in the current industry, a single ring closed pulsating heat pipe (PHP) was simulated in this paper. Firstly, the geometry model and numerical simulation model of single ring closed cycle PHP were established to obtain the temperature change rule of PHP and the position motion state of the vapor-plug and liquidcolumn in the tube. At the same time, a test bench was set up to verify the accuracy of the simulation results. The time series data of temperature and position of vapor-plug and liquidcolumn in PHP are extracted, and the chaotic characteristics of PHP are obtained. The results show that with the increase of the heating power, the motion state of the working fluid, the chaotic attractor and Lyapunov index have all changed significantly. The results provide a foundation for further research on the features and mechanism of PHP.
Effects of solvent extraction on the microstructure of bituminous coal-based graphite
Wang Lipeng,Yao Zongxu,Guo Zhimin,Shen Xiaofeng,Li Zhiang,Zhou Zhengqi,Wang Yuling,Yang Jian-Guo 한국탄소학회 2022 Carbon Letters Vol.32 No.3
Coal-based graphite has become the main material of emerging industries. The microstructure of coal-based graphite plays an important role in its applications in many fields. In this paper, the effect of carbon disulfide/N-methyl-2-pyrrolidone solvent mixture extraction on the microstructure of bituminous coal-based graphite was systematically studied through preliminary extraction coupled with high-temperature graphitization. The graphitization degree g (75.65%) of the coal residue-based graphite was significantly higher than that of the raw coal-based graphite. The crystallite size La of the coal residue-based graphite was reduced by 47.06% compared with the raw coal-based graphite. The ID/ IG value of the coal residue-based graphite is smaller than that of the raw coal-based graphite. The specific surface area (16.72 m2/g) and total pore volume (0.0567 m3/g) of the coal residue-based graphite are increased in varying degrees compared with the raw coal-based graphite. This study found a carbon source that can be used to prepare coal-based graphite with high graphitization degree. The results are expected to provide a theoretical basis for further clean and efficient utilization of the coal residue resources.
Lipeng Wang,Xiangli Jiang,Zhi Zhang 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.6
The model predictive control (MPC) and neural network (NN) are utilized to establish an automatic carrier landing system (ACLS) guidance law in the lateral plane, which achieves the objective of eliminating the lateral landing risk and lateral state deviations, and compensating the deck motion. For this motivation, the nonlinear lateral kinetic function is transformed into a polytopic model based on the landing state deviations. The NN is used to construct the lateral deck motion compensation (DMC) so that the proposed method can track the dynamic lateral desired glide slope. The NN outputs the controlled variables, which compensate the aileron and rudder manipulations in the MPC algorithm. The previous risk model provides the current landing risk numerical value that are introduced into the MPC performance. The landing state deviations, landing risk, and deck motion is considered in the solution of several linear matrix inequalities (LMIs). The input and output constraints are transformed into LMIs to maintain the feasible of the lateral actuators of the aircraft. The off-line design strategy of weight matrices is adopted to enhance the calculation speed and robust. Finally, three simulation examples are executed on a semiphysical platform based on the original nonlinear landing model, which verify the excellent multiple constraints optimization performance of the proposed method.
Thermal management analysis of serial-connection three-chamber piezoelectric pump
Lipeng He,Xiaoqiang Wu,Zheng Zhang,Jingran Wang,Dianbin Hu,Yamei Liu,Guangming Cheng 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.10
The design of a micropump with high performance and excellent reliability on thermal management still remains a challenge for electronic cooling. The performance of a piezoelectric pump with 3 chambers connected in series on thermal management was investigated for electronic cooling in this study. Two S-shaped channel heat sinks and the piezoelectric pump with 3 chambers connected in series were combined to form a loop cooling system. With water as the pumping medium, the tested pump has a flow rate most up to 690.6 ml/min at an input voltage of 220 V and an input frequency of 110 Hz. Suitability of the system has been demonstrated through simulation analysis and experimental verification for temperature control. A temperature reduction of 3 °C of CPU could be achieved at 250 mL/min flow rate generated by the piezoelectric pump with 3 chambers connected in series.
BCN Graphene as Efficient Metal‐Free Electrocatalyst for the Oxygen Reduction Reaction
Wang, Shuangyin,Zhang, Lipeng,Xia, Zhenhai,Roy, Ajit,Chang, Dong Wook,Baek, Jong‐,Beom,Dai, Liming WILEY‐VCH Verlag 2012 Angewandte Chemie Vol.124 No.17
<P><B>Einen einfachen Zugang</B> zu B,N‐dotiertem Graphen mit einstellbarer Zusammensetzung eröffnet das Tempern von Graphenoxid in Gegenwart von Borsäure und Ammoniak. Das gebildete BCN‐Graphen (siehe Bild; C grau, H weiß, B rosa, N blau) ist bei der Sauerstoffreduktion in alkalischem Milieu ein aktiverer Katalysator als kommerzielle Pt/C‐Elektrokatalysatoren.</P>
A Text Clustering Algorithm based on Weeds and Differential Optimization
Lipeng YANG,Fuzhang WANG,Chunmei FAN 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.12
Invasive weed optimization (IWO) is a swarm optimization algorithm with both explorative and exploitive power where the diverisity of the population is obtained by allowing the reproduction and mutation of individuals with poor fitness .Differential optimization algorithm is a random parallel algorithm according to a vector change that can make individuals change toward outstanding individuals with global convergence. For k-means algorithm , the traditional algorirhm is prone to get stuck at local optimum and is sensitive to random initialization. Based on the aforementiond background a novel optimization algorithm based hybriding DE and IWO which denoted IWODE-KM is employed to optimize the parameters of k-means and is further applied to chinese text clustering. Experiment results shows that the proposed method outperforms both of its ancestors.
Yongchao Liu,Qidan Zhu,Lipeng Wang 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.2
This article focuses on designing a robust adaptive fuzzy asymptotic control method for uncertain switched nonlinear systems in presence of arbitrary switching signals. The unknown dynamics of switched systems are addressed by making use of fuzzy logic systems. Different from the existing approximation-based schemes, the asymptotic tracking performance is achieved by employing a bound estimation method, some smooth functions and the backstepping technique. Through constructing Lyapunov function, the devised scheme can guarantee the stability and asymptotic convergence character of the controlled systems. Finally, the availability of the presented approach is verified via simulation examples.