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Zheng, W.,Shen, R. F.,Sakamoto, T.,Beardmore, A. P.,De Pasquale, M.,Wu, X. F.,Gorosabel, J.,Urata, Y.,Sugita, S.,Zhang, B.,Pozanenko, A.,Nissinen, M.,Sahu, D. K.,Im, M.,Ukwatta, T. N.,Andreev, M.,Klun IOP Publishing 2012 The Astrophysical journal Vol.751 No.2
<P>We present a comprehensive analysis of a bright, long-duration (T-90 similar to 257 s) GRB 110205A at redshift z = 2.22. The optical prompt emission was detected by Swift/UVOT, ROTSE-IIIb, and BOOTES telescopes when the gamma-ray burst (GRB) was still radiating in the gamma-ray band, with optical light curve showing correlation with gamma-ray data. Nearly 200 s of observations were obtained simultaneously from optical, X-ray, to gamma-ray (1 eV to 5 MeV), which makes it one of the exceptional cases to study the broadband spectral energy distribution during the prompt emission phase. In particular, we clearly identify, for the first time, an interesting two-break energy spectrum, roughly consistent with the standard synchrotron emission model in the fast cooling regime. Shortly after prompt emission (similar to 1100 s), a bright (R = 14.0) optical emission hump with very steep rise (alpha similar to 5.5) was observed, which we interpret as the reverse shock (RS) emission. It is the first time that the rising phase of an RS component has been closely observed. The full optical and X-ray afterglow light curves can be interpreted within the standard reverse shock (RS) + forward shock (FS) model. In general, the high-quality prompt and afterglow data allow us to apply the standard fireball model to extract valuable information, including the radiation mechanism (synchrotron), radius of prompt emission (R-GRB similar to 3 x 10(13) cm), initial Lorentz factor of the outflow (Gamma(0) similar to 250), the composition of the ejecta (mildly magnetized), the collimation angle, and the total energy budget.</P>
He, D.,Zheng, C.,Wang, Q.,He, C.,Lee, Y.I.,Wu, L.,Hou, X. Pergamon Press ; Elsevier Science Ltd 2015 Talanta Vol.142 No.-
In this work, we proposed a dielectric barrier discharge (DBD)-assisted one-pot strategy to fabricate carbon quantum dots (CQDs) using only one reagent N, N-dimethylformamide (DMF) at atmospheric pressure and room temperature. The experimental conditions were carefully investigated, and the prepared CQDs were characterized by using UV-vis spectrophotometer, fluorescence spectrophotometer, Fourier transform infrared (FTIR) spectrometer, transmission electron microscopy (TEM) and X-ray photoelectron spectrometer (XPS). The CQDs have an average size of 3.6nm in diameter with narrow size distribution, and can be used as highly selective and sensitive fluorescence probes for hydrogen peroxide and glucose, with limits of detection of 3.8μM and 3.5μM, respectively.
Comparison of Axi-symmetric Single-Hole Nozzle with Multi-Hole Sac Nozzles
( M. C. Lai ),( Y. Zheng ),( X. Xie ),( K. Im ),( S. Moon ),( Z. Liu ),( J. Gao ),( J. Wang ),( J. M. Shi ),( R. E. Winsor ) 한국액체미립화학회 2010 한국액체미립화학회 학술강연회 논문집 Vol.2010 No.-
It is well know that the internal flow field and nozzle geometry affect the spray behavior, but without high-speed microscopic visualization, it is difficult to characterize the spray structure in details. Single-hole Diesel injectors have been used in fundamental spray research, while most direct-injection engines use multi-hole nozzle to tailor the fuel spray to the combustion chamber geometry. Recent engine trends also use smaller orifice and higher injection pressure. This paper discussed the quasi-steady near-nozzle Diesel spray structures of an axisymmetric single-hole nozzle and a symmetric two-hole nozzle configuration, with a nominal nozzle size of 130 ㎛. Both nozzle holes originate from a sac of identical geometry, but different flow structure inside the nozzle cause significant difference in the observed flow structure near the nozzle exit. The ultrafast fast Phase-contrast X-ray images revealed unique surface and internal morphology of the fuel sprays that can be identified. The two-hole nozzle produces much more unstable jet structure under same injection conditions. The early wavelength developed in the jet is measured to be 30~80 ㎛, depending on the injection conditions. The differences between the nozzle configurations are investigated using CFD simulation. The results show that the three-dimensional fluid flow entering the two-hole nozzle generates stronger streamline curvature and stream-wise vortices which are by default absent in the axisymmetric single-hole nozzle. It also produces thicker shear layer and higher turbulence. The interactions of downwash entrance flow with turbulence potentially enhance the instability and produce wider spray cone angles. The number of holes also has interesting effects on the strength of the vortices and the downwash.
DNA 분석을 통한 한우 , 연변황우 및 화우의 유전적 특성
신원집,여정수,김재우,신수길,정진우,이지홍 한국축산학회 1999 한국축산학회지 Vol.41 No.4
This study was conducted to identify the genetic parameters and genetic relationships among 3 cattle breeds of Hanwoo (Korea), Yanbian yellow cattle (China), and Wagyu (Japan). DNA fingerprinting was prepared using M13 probe and Pst 1 enzyme. Genetic homogencities of Hanwoo and Yanbian yellow cattle were comparatively lower than that of Wagyu, suggesting genetic improvement by active breeding program for Wagyu compared to Hanwoo and Yanbian yellow cattle and possibility of improvement capacity for Hanwoo and Yanbian yellow cattle. Genetic similarities between breeds were not significantly different among them, suggesting that these 3 breeds have been raised independently without any inflow or outflow of gene source for a while.
Tokamak plasma disruption precursor onset time study based on semi-supervised anomaly detection
X.K. Ai,W. Zheng,M. Zhang,D.L. Chen,C.S. Shen,B.H. Guo,B.J. Xiao,Y. Zhong,N.C. Wang,Z.J. Yang,Z.P. Chen,Z.Y. Chen,Y.H. Ding,Y. Pan Korean Nuclear Society 2024 Nuclear Engineering and Technology Vol.56 No.4
Plasma disruption in tokamak experiments is a challenging issue that causes damage to the device. Reliable prediction methods are needed, but the lack of full understanding of plasma disruption limits the effectiveness of physics-driven methods. Data-driven methods based on supervised learning are commonly used, and they rely on labelled training data. However, manual labelling of disruption precursors is a time-consuming and challenging task, as some precursors are difficult to accurately identify. The mainstream labelling methods assume that the precursor onset occurs at a fixed time before disruption, which leads to mislabeled samples and suboptimal prediction performance. In this paper, we present disruption prediction methods based on anomaly detection to address these issues, demonstrating good prediction performance on J-TEXT and EAST. By evaluating precursor onset times using different anomaly detection algorithms, it is found that labelling methods can be improved since the onset times of different shots are not necessarily the same. The study optimizes precursor labelling using the onset times inferred by the anomaly detection predictor and test the optimized labels on supervised learning disruption predictors. The results on J-TEXT and EAST show that the models trained on the optimized labels outperform those trained on fixed onset time labels.
EXPERIMENTAL STUDY OF EGR COOLER REGENERATION AIDED BY OXYGEN-FED NTP AND AIR-FED NTP
Y. X. SHI,Y. ZHENG,Y. X. CAI,W. J. LI,H. XU 한국자동차공학회 2016 International journal of automotive technology Vol.17 No.3
Based on non-thermal plasma (NTP) technology fed by oxygen and air as the gas source respectively, the experimental system of exhaust gas recirculation (EGR) cooler regeneration was built to do a study at different regeneration temperatures. By measuring the concentration of main active substance and COx in regeneration process, the influence of temperature on regeneration aided by oxygen-fed NTP and air-fed NTP was investigated. The experimental results indicate that EGR cooler can be regenerated both by air-fed NTP and oxygen-fed NTP at a wide temperature range of 18 oC ~ 300 oC. By comparison of the regeneration with oxygen-fed NTP and air-fed NTP, it can be easily known that the regeneration effect is most remarkable at 150 oC with oxygen-fed NTP and at 120 oC with air-fed NTP. In addition, when the temperature is below 150 oC especially at 120 oC, the regeneration efficiency of air-fed NTP is lower than oxygen-fed NTP, nevertheless, when the temperature is above 150 oC, air-fed NTP has a superiority in regeneration and the higher the temperature is, the more obvious the superiority will be.
A Numerical Method to Optimize the Structure of a Magneto-Optical Disk
Y.-X. Zheng,J. H. Qiu,L. Y. Chen,. Y. Wang 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.2
In magneto-optical (MO) data storage, data are recorded by different magnetization directions of magnetic domains and reproduced by the magneto-optical Kerr effect. Recently, the areal density of MO storage has been demonstrated to reach 100 Gbit/in2. In order to achieve high performance for an MO disk, it is required to get a high MO signal by carefully choosing the structure parameters and material parameters. In this paper, we propose a numerical method to optimize the structure parameters for an MO disk.
EXPERIMENTAL STUDY ON REGENERATING FOULED EGR COOLER BY NTPI TECHNOLOGY
Y. Y. CHEN,Y. X. CAI,X. H. LI,Y. X. SHI,Y. ZHENG 한국자동차공학회 2015 International journal of automotive technology Vol.16 No.2
In order to investigate the regeneration effect of non-thermal plasma injection (NTPI) technology on fouled exhaust gas recirculation (EGR) cooler, NTPI regeneration apparatus and EGR cooler performance test system were built up. Results showed that non-thermal plasma (NTP) could peel off the deposit layer and improve the heat exchange performance effectively. The carbon removal energy efficiency of this NTPI regeneration setup was 22.46 g/kWh and the O3 utilization ratio was 96.50%. To get a deeper understanding of the regeneration effect, thermo-gravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) were introduced to investigate the variation of deposit layer’s physical and chemical characteristics before and after regeneration. Results showed that the content of soluble organic fraction (SOF) in deposit specimen decreased obviously, mainly because the carbonyls were effectively removed by NTP. Moreover, soot in deposit specimen was successfully activated by NTP.