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LI Kunpeng,LIU Wei,LI Qunzhan,ZHAO Yunyun,HE Zhixin,SHI Haiou,JIN Shoujie,CHEN Guangzan 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
The rational use of regenerative braking energy for urban rail transit trains directly affects the voltage safety of the traction power supply system and the electric braking function of the train. It is also of great significance for the implementation of train traction energy saving. This paper proposes a scheme of train regenerative braking ground absorbing device based on super-capacitor energy storage. It adopts multiple modular Buck/Boost DC conversion topology to realize bidirectional control of electric energy and stabilize the secondary utilization of traction network voltage and regenerative electric energy. According to the scheme of this paper, the energy storage device was developed and verified in the engineering of the Guangzhou Line 6 main line traction substation. The test indicators have met the design expectations.
Kunpeng Liu,Nan Wang,Jianhua Li,Fanglin Du,Baorong Hou,Ruiyong Zhang 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.128 No.-
Electrochemical two-electron water oxidation reaction (2e WOR) to produce H2O2 has been widely concerned. However, four-electron competition reaction causes the large overpotential and low productionrates of 2e WOR, which restrict its’ development and application. Herein, we prepared N-TiO2 derivedfrom NH2-MIL-125 by the hydrothermal combined with calcination method. We found that N-TiO2 asphotoanode exhibited the well properties of photoelectrocatalysis water oxidation, which gave an overpotentialof 630 mV at 1 mA cm2. The overpotentials of N-TiO2 was approximately 130 mV (at1 mA cm2) lower than NH2-MIL-125, and even lower than the previous reported TiO2, which may attributeto the increased oxygen vacancy with the calcination process and N doping. In addition, we investigatedthe degradation performance of the prepared catalysts to degrade methylene blue byphotoelctrocatalysis on-site the preparation of H2O2. It was shown that N-TiO2 performed high degradationefficiency (91%) and excellent stability. The possible mechanism was speculated due to theincreased oxygen vacancy and N doping. This work provides a new idea for photoelectrocatalysis wateroxidation materials and points out a new way for on-site H2O2 production for direct use
Theoretical and numerical investigation on impact noise radiated by collision of two cylinders
Yinggang Li,Tianning Chen,Xiaopeng Wang,Kunpeng Yu,Chao Zhang 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.6
Impact noise characterized by high peak value and short duration is very common source of noise in the industries and in many casescan be summed up in the noise radiated by collision of two cylinders. In order to precisely predict the impact noise radiated by collisionof two cylinders, a modified theoretical prediction model was established based on the Palmgren’s cylinder contact empirical model andacoustics theory. Then a numerical simulation method combining the finite element method (FEM) and the transient boundary elementmethod (TBEM) had been presented to verify the modified theoretical model and further discuss the mechanism of impact noise. Boththe contact force and impact noise of collision cylinders by the modified theoretical model were compared with the numerical results aswell as the prediction results by the original theoretical model. It indicated that the results by modified theoretical prediction model are ingood agreement with the numerical results, indicating better prediction superior to the original model. The impact noise radiated by collisioncylinders is attributed to the rigid body acceleration. Furthermore, the experimental validations were conducted to verify the modifiedtheoretical prediction model and numerical simulation results.
Liu, Kun,Wang, Kunpeng,Wang, Yihui,Li, Yulong The Society of Naval Architects of Korea 2020 International Journal of Naval Architecture and Oc Vol.12 No.-
The present study proposes a time domain model for the Vortex-induced Vibration (VIV) simulation of a catenary riser under the combination of the current and oscillatory flow induced by vessel motion. In this model, the hydrodynamic force of VIV comprises excitation force, hydrodynamic damping and added mass, which are taken as functions of the non-dimensional frequency and amplitude ratio. The non-dimensional frequency is related with the response frequency, natural frequency, lock-in range and the fluid velocity. The relatively oscillatory flow induced by vessel motion is taken into account in the fluid velocity. Considering that the added mass coefficient and the non-dimensional frequency can affect each other, an iterative analysis is conducted at each time step to update the added mass coefficient and the natural frequency. This model is in detail validated against the published test models. The results show that the model can reasonably reflect the effect of the added mass coefficient on the VIV, and can well predict the riser's VIV under stationary and oscillatory flow induced by vessel motion. Based on the model, this study carries out the VIV simulation of a catenary riser with harmonic vessel motion. By analyzing the bending moment near the touchdown point, it is found that under the combination of the ocean current and oscillatory flow the vessel motion may decrease the VIV response, while increase the excited frequencies. In addition, the decreasing rate of the VIV under vessel surge is larger than that under vessel heave at small vessel motion velocity, while the situation becomes opposite at large vessel motion velocity.
Liu, Kun,Wang, Kunpeng,Wang, Yihui,Li, Yulong The Society of Naval Architects of Korea 2020 International Journal of Naval Architecture and Oc Vol.12 No.1
The present study proposes a time domain model for the Vortex-induced Vibration (VIV) simulation of a catenary riser under the combination of the current and oscillatory flow induced by vessel motion. In this model, the hydrodynamic force of VIV comprises excitation force, hydrodynamic damping and added mass, which are taken as functions of the non-dimensional frequency and amplitude ratio. The non-dimensional frequency is related with the response frequency, natural frequency, lock-in range and the fluid velocity. The relatively oscillatory flow induced by vessel motion is taken into account in the fluid velocity. Considering that the added mass coefficient and the non-dimensional frequency can affect each other, an iterative analysis is conducted at each time step to update the added mass coefficient and the natural frequency. This model is in detail validated against the published test models. The results show that the model can reasonably reflect the effect of the added mass coefficient on the VIV, and can well predict the riser's VIV under stationary and oscillatory flow induced by vessel motion. Based on the model, this study carries out the VIV simulation of a catenary riser with harmonic vessel motion. By analyzing the bending moment near the touchdown point, it is found that under the combination of the ocean current and oscillatory flow the vessel motion may decrease the VIV response, while increase the excited frequencies. In addition, the decreasing rate of the VIV under vessel surge is larger than that under vessel heave at small vessel motion velocity, while the situation becomes opposite at large vessel motion velocity.
Recent Progress of Gr/Si Schottky Photodetectors
Qingguo Shao,Hao Qi,Chao Li,Kunpeng Cai,Jianxia Dong,Xuhui Liu,Ning Cao,Xiaobei Zang 대한금속·재료학회 2023 ELECTRONIC MATERIALS LETTERS Vol.19 No.2
By combing the carrier mobility of graphene with the excellent light absorption properties of silicon, ultra-shallow Schottkyjunction can be obtained, and can exist stably for a long time. The photoelectric property of Schottky junction is determinednot only by graphene and silicon semiconductor layer, but also by the interface layer between the two. Through a series ofoptimizations, the performance of graphene/silicon Schottky junction photodetectors can be continuously improved. Asa result, graphene/silicon Schottky junctions more promising for the development of next generation photodetectors withits stability, ease of preparation and sensitivity. In this review, we firstly give a brief introduction to Gr Schottky junctionphotodetectors, and then present a comprehensive review on the recent progress of optimizing Gr/Si Schottky junction photodetectorsin the past few years, including light management engineering, band engineering and interfacial engineering. Finally, the current challenges are summarized and further perspectives are outlined.
Effect of naphthalene quinoline and H2S on DBT hydrodesulfurization over unsupported NiMoW catalyst
Changlong Yin,Haonan Zhang,Tongtong Wu,Zhuyan Wu,Kunpeng Li,Yan Kong,Chengwu Dong,Chenguang Liu 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.12
Unsupported catalysts have attracted much attention for high activity in comparison with the traditional supported catalyst. Meanwhile, the clear structure of unsupported catalysts is helpful for the recognition of active phase for conducting the industry production. The NiMoW unsupported catalyst was prepared by hydrothermal synthesis and characterized by BET, XRD and HRTEM. The effects of naphthalene, quinoline and H2S on the hydrodesulfurization reactivity of dibenzothiophene (DBT) were investigated in both a batch autoclave and a continuous 10 ml fixed bed micro-reactor over NiMoW and supported catalyst for comparison. The results showed that the hydrogenation reaction and the hydrogenolysis reaction occurred on different active sites. For supported catalyst, the inhibition was relatively weaker, and the inhibition of the hydrodesulfurization pathway was much higher than the direct desulfurization pathway. Although unsupported catalyst was very sensitive to quinoline and H2S in this experiment, the HDS ratio on the unsupported catalyst was maintained at a high level above 99.7%, which is attributed to the very high active site density of unsupported catalysts.