Seismo-ionospheric anomalies associated with Mw 7.8 Nepal earthquake on 2015 April 25 from CMONOC GPS data

Kunpeng Shi,Jinyun Guo,Xin Liu,Lu Liu,Xinzhao You,Fangjian Wang 한국지질과학협의회 2020 Geosciences Journal Vol.24 No.4

To explore the ionospheric coupling mechanism, the total electron contents (TECs) and slant TECs (STECs) were processed from GPS sites in China, Nepal and India, and the singular spectrum analysis (SSA) method was introduced to investigate the seismic-ionospheric signals prior to the Mw7.8 Nepal earthquake on April 25, 2015. The results of pre-earthquake ionospheric anomaly show that there were obviously positive on 2nd day and negative anomalies on 14th day prior to the earthquake, respectively. The radius of anomalous area with a regular elliptical shape reached 2500 km and 2000 km in the above days respectively, which was close to the radius of Nepal earthquake. After excluding the moving effects of ionosphere hump, the investigation by the global ionosphere maps (GIMs) shows that a wide TEC abnormality appeared over the epicenter and conjugated region with the duration of 12 hr. Besides, the magnitude of TEC anomalies impending the shock, with its peaks happening at the midday (local time), was proportional to the number of days prior to the occurrence. By using the STECs within seismogenic zone, we further studied the coseismic ionospheric disturbance (CID) of Nepal earthquake. The results show that two modes of CID propagation velocity have been detected. Due to the TEC respond of Rayleigh wave, one mode had average propagating speed of 1.3 km/s in the near-field within 800 km, and gradually reaching up to 2.7 km/s in the far-field beyond 2000 km. Another mode had average propagating speed of 0.6 km/s only existing in the near-field, which was in accordance with the speed of shock acoustic waves. Besides, CID intensity presented the obvious directional difference. The ambient magnetic field around the epicenter made it easier for CID to spread in the southward direction, the plateau topography also prohibited the propagation of ionospheric disturbance, and most CID points were detected along the southeast direction of the epicenter which is consistent with the rupture propagation.

Phtotoelectrochemical water oxidation to H2O2 based on N-TiO2 derived from NH2-MIL-125 and in-situ application on degradation dye

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

Numerical simulation in time domain to study cross-flow VIV of catenary riser subject to vessel motion-induced oscillatory current

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.

Numerical simulation in time domain to study cross-flow VIV of catenary riser subject to vessel motion-induced oscillatory current

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.

Development of Train Regenerative Braking Ground Absorbing Device Based on Super Capacitor Energy Storage

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.

Bioinformatic and integrated analysis identifies an lncRNA–miRNA–mRNA interaction mechanism in gastric adenocarcinoma

Yong Liao,Wen Cao,Kunpeng Zhang,Yang Zhou,Xin Xu,Xiaoling Zhao,Xu Yang,Jitao Wang,Shouwen Zhao,Shiyu Zhang,Longfei Yang,Dengxiang Liu,Yanpeng Tian,Weizhong Wu 한국유전학회 2021 Genes & Genomics Vol.43 No.6

Background lncRNAs–miRNAs–mRNAs networks play an important role in Gastric adenocarcinoma (GA). Identifcation of these networks provide new insight into the role of these RNAs in gastric cancer. Objectives Biological information databases were screened to characterize and examine the regulatory networks and to further investigate the potential prognostic relationship this regulation has in GA. Methods By mining The Cancer Genome Atlas (TCGA) database, we gathered information on GA-related lncRNAs, miRNAs, and mRNAs. We identifed diferentially expressed (DE) lncRNAs, miRNAs, and mRNAs using R software. The lncRNA–miRNA–mRNA interaction network was constructed and subsequent survival examination was performed. Representative genes were selected out using The Biological Networks Gene Ontology plug-in tool on Cytoscape. Additional analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) terms were used to screen representative genes for functional enrichment. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) were used to identify the expression of fve candidate diferential expressed RNAs. Results Information of samples from 375 cases of gastric cancer and 32 healthy cases (normal tissues) were downloaded from the TCGA database. A total of 1632 DE-mRNAs, 1008 DE-lncRNAs and 104 DE-miRNAs were identifed and screened. Among them, 65 DE-lncRNAs, 10 DE-miRNAs, and 10 DE-mRNAs form lncRNAs–miRNAs–mRNAs regulatory network. Additionally, 10 lncRNAs and 2 mRNAs were associated with the prognosis of GA. Multivariable COX analysis revealed that AC018781.1 and VCAN-AS1 were independent risk factors for GA. GO functional enrichment analysis found DE-mRNA was signifcantly enriched TERM (P<0.05). The KEGG signal regulatory network analysis found 11 signifcantly enrichment networks, the most prevailing was for the AGE-RAGE signaling pathway associated with Diabetic complications. Results of RT-qPCR was consistent with the in silico results. Conclusions The results of the present study represent a view of GA from a analysis of lncRNA, miRNA and mRNA. The network of lncRNA–miRNA–mRNA interactions revealed here may potentially further experimental studies and may help biomarker development for GA.

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.