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Regional innovation networks and risk analysis based on Industry-University-Reserach Institution
Feng Feng,Xue Qin 인하대학교 정석물류통상연구원 2009 인하대학교 정석물류통상연구원 학술대회 Vol.2009 No.10
According to the system theory, the structure of the network determines characteristics of the network. Our paper builds a regional innovation network of Industry-University-Research Institution and analyzes the network structure variables the aggregation coefficient, average shortest path length, degree distribution by social network model. The result is obtaining the contact between network structure variables and risks, which will improve and promote the formation and development of the regional innovation networks based on Industry-University-Research Institution.
Positively Charged and pH-sensitive Carbon Dots for Fluorescence Detection of Copper Ion
Feng Feng,Chenfang Miao,Yalan Zhang,Zhengjun Huang,Shaohuang Weng 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.2
As an essential trace element in the human body, copper ion (Cu2+) performs an important role in many fundamental physiological processes that need a facile and effective method for the monitoring of Cu2+ in organisms. Herein, a turn-off, facile fluorescent strategy for sensing Cu2+ was proposed using positively charged carbon dots (P-CDs) as probe. The P-CDs prepared from melting strategy exhibited stable, biocompatible, and pH-sensitive luminescent properties. P-CDs can be selectively quenched by Cu2+ for the direct detection of Cu2+. The reaction mechanism between Cu2+ and P-CDs was systematically investigated, illustrating that Cu2+ coordinated with the surface functional groups in P-CDs. The binding effect of Cu2+ and P-CDs caused the constant morphology and static quenching behavior of P-CDs. The promising accuracy of the testing results of the addition of Cu2+ in diluted serum using P-CDs implied their extended application in the biological field.
Feng Feng,Liang Shen 대한수학회 2019 대한수학회보 Vol.56 No.1
This article mainly concentrates on the open question wheth\-er a right self-injective ring $R$ is necessary QF if $R/S_l$ is left Goldie. It is answered affirmatively under the condition $S_l\subseteq S_r$, where $S_l$ and $S_r$ denote the left socle and right socle of $R$ respectively. And the original condition ``right self-injective" can be weakened to ``right CS and right P-injective". It is also proved that a semiperfect, left and right mininjective ring $R$ is QF if $S_r\subseteq^{ess}R_R$ and $R/S_l$ is left Goldie.
Numerical Study of Coherent Structures and Sound Radiation in a High Subsonic Jet
Feng Feng,Qiang Wang 한국전산유체공학회 2014 한국전산유체공학회 학술대회논문집 Vol.2014 No.10
The noise radiated by subsonic turbulent jet with a Mach number of 0.9 is investigated by the high-order accuracy parallel compressible LES (Large Eddy Simulation) method, and the far field sound is solved and analyzed by the permeable FW-H (Ffowcs Williams-Hawkings) wave extrapolation method. The jet mean flow and turbulence statistics is verified carefully to ensure the fidelity and accuracy of the simulation. Applying the frequency domain permeable FW-H method educe the predominant sound mode of the jet flow, and it is found that the coherent structures or the instability waves at the potential core end region form the low wave number wave packets lead to the predominant sound modes radiation.
Fengfeng Du,Xiaoming Ni,Runsheng Lv,Xuxing Feng 한국지질과학협의회 2023 Geosciences Journal Vol.27 No.2
In addition to reservoir geological factors, economic benefits are another important factor that determines the feasibility of co-layer drainage. In view of this, this paper takes the 3# and 15# coal seams in the Wangcun-Xiadian block of the Qinshui Basin (Shanxi Province, China) as the research object, adopts the step-by-step method to summarize the geological influencing factors and thresholds of the drainage of the total combined seam, and eliminates the unsuitable geological conditions blocks for layer development. Using the productivity numerical simulation software combined with the constructed economic evaluation model, the suitable blocks for co-production in this zone were identified. The one-sidedness of the evaluation results caused by only considering the geological reservoir conditions is avoided, and the practicability of the evaluation results is guaranteed. The results indicate that the difference of formation liquid supply capacity between the two layers of coal is the key factor affecting combined layer drainage. When the gas content of 3# coal seam is 8,15m3/t and the post-fracturing permeability exceeds 5.17 × 10−3μm2 and 1.13 × 10−3μm2 respectively, it is suitable for single development of 3# coal seam. When the geological conditions for commingled production are met, it is suitable for simultaneous development of 3# and 15# when the permeability after fracturing exceeds 6.27 × 10−3μm2 and 1.31 × 10−3μm2 respectively under the same gas content. The study methodology considers both geological reservoirs and economic benefits, which can more objectively and accurately evaluate the suitable development blocks.
Research on fault diagnosis method of reciprocating compressor valve based on IVMD-CMS model
Fengfeng Bie,Suzhen Chen,Fengxia Lyu,Hongfei Zhu,Qianqian Li,Xinting Miao 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.8
As for the complex shock vibration characteristics, the issue of difficult to extract the characteristic information of reciprocating compressor valve, a fault diagnosis method combining informational variational mode decomposition (IVMD) and cyclic modulation spectrum (CMS) is proposed. In this paper, the Bayesian information criterion (BIC) is optimized for the VMD decomposition parameter firstly, and the obtained IVMD algorithm is applied to decompose the signal into intrinsic mode functions (IMFs). Secondly, the signal is reconstructed with the correlation coefficient. Finally, the CMS algorithm is utilized for the reconstructed signal analysis, from which main spectral features of the carrier frequency and cyclic frequency on the cyclic modulation spectrum are obtained. The characteristic information of the signal is highlighted with the amplitude and relationship of the frequency feature. The effectiveness and superiority of the method in the diagnosis of reciprocating compressor valve faults are demonstrated with the numerical simulation and experimental analysis.
Eu3+-site occupation in CaTiO3 perovskite material at low temperature
Fengfeng Chi,Yanguang Qin,Shaoshuai Zhou,Xiantao Wei,Yonghu Chen,Changkui Duan,Min Yin 한국물리학회 2017 Current Applied Physics Vol.17 No.1
In order to clarify the site occupancy of rare-earth ions in rare-earth doped perovskite materials, the undoped pure CaTiO3 and Eu3þ-doped CaTiO3 samples with a series of Ca/Ti ratio were synthesized via high-temperature solid-state reaction method. X-ray diffraction (XRD) powder patterns confirm that the crystal structure keeps invariant at various Ca/Ti ratios. Measurement results of unit-cell parameters and X-ray photoelectron spectroscopy (XPS) indicate that Eu3þ ions enter into the Ca2þ site. The highresolution photoluminescence spectra of Eu3þ ions at 20 K in all samples did not witness a significant change under the excitation at different wavelength, implying that Eu3þ ions occupy only one type of site. Considering the small spectral splitting range of 5D0/7F2 transition and the large intensity ratio of 5D0 / 7F2/5D0 / 7F1, it can be concluded that Eu3þ occupies Ca2þ site with larger coordinate numbers rather than Ti4þ site.
Fengfeng Hu,Yu Sun,Binbin Peng 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.10
An elastic dynamic model of high-speed multi-link precision press considering structural stiffness of rotation joints was established by the finite element method. In the finite element model, rotation joint was established by four bar elements with equivalent stiffness, and connected link was established by beam element. Then, the elastic dynamics equation of the system was established, and modal superposition method was used to solve the dynamic response. Compared with the traditional elastic dynamic model with perfect constraint of the rotation joints, the elastic dynamic response value of the improved model is larger. To validate the presented new method of elastic dynamics analysis with stiffness of rotation joints, a related test of slider Bottom dead center (BDC) position in different speed was designed. The test shows that the model with stiffness of rotation joints is more reasonable. So it provides a reasonable theory and method for dynamic characteristics research of sucha multi-link machine.
Increasing Persona Effects: Does It Matter the Voice and Appearance of Animated Pedagogical Agent
( Jeeheon Ryu ),( Fengfeng Ke ) 한국교육공학회 2018 Educational Technology International Vol.19 No.1
The animated pedagogical agent has been implemented to promote learning outcomes and motivation in multimedia learning. It has been claimed that one of the advantages of using pedagogical agent is persona effect - the personalization or social presence of pedagogical agent can enhance learning engagement and motivation. However, prior research is inconclusive as to whether and how the features of the pedagogical agent have effects on the persona effect. This study investigated whether the similarity between a pedagogical agent and the real instructor in terms of the voice and outlook would improve students’ perception of the agent’s persona. The study also examined the effect by the size of pedagogical agent on the persona perception. Two experiments were conducted with a total of 115 college students. Experiment 1 indicated a significant main effect of voice on the persona perception. Experiment 2 was conducted to examine whether the size of pedagogical agent would affect the voice effect on the persona perception. The results showed that the instructor-like voice yielded higher persona perception regardless of the pedagogical agent’s size. Overall, the study findings indicated that the similarity in voice positively fostered the agent’s persona.