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Changqing Ren,Fugui He,Xianzhi Gao,Dongsheng Wu,Wenli Yao,Jianzhang Tian,Huiping Guo,Yuanxin Huang,Li Wang,Han Feng,Junwei Li 한국지질과학협의회 2019 Geosciences Journal Vol.23 No.6
The Shulu Sag which is a rifted sag with NNE trend is located in the south of Jizhong Depression, Bohai Bay Basin, northern China. The gentle slope and three troughs are situated in the west and east of the sag, respectively. Both of the lower part of Shasan Member (Es3x) and the lower part of Shayi Member (Es1x) act as source rocks in this sag. Researches on the type, quantity, quality and thermal maturity of the respective organic matter have been conducted using Rock-Eval pyrolysis data. Type II is the dominant kerogen in Es1x of all troughs. However, Type II1 and III is the dominant kerogen in Es3x of Middle-Southern and Northern trough, respectively. TOC (total organic carbon) and pyrolysis S2 (hydrocarbon) values suggest that the Es1x source rocks in Middle-Southern and Northern trough are fair to good and poor to fair generative potential of hydrocarbon, separately. The Es3x source rocks in Middle-Southern and Northern trough possess fair to excellent and poor to fair generative potential of hydrocarbon, individually. Tmax (pyrolysis temperature at maximum S2) values indicate that most of Es3x samples are thermally mature, but all Es1x samples are thermally immature. Under large scale condition, the hydrocarbon secondary migration in the upper part of Shasan Member (Es3s), Shaer Member (Es2) and the upper part of Shayi Member (Es1s) have been simulated using fluid potential model with Arcgis 9.3 software. The simulation results reveal the direction of hydrocarbon secondary migration and the distribution of hydrocarbon migration-accumulation units (HMAUS), and also suggest that the hydrocarbon migration direction is obviously controlled by nose-like structure belts where most of hydrocarbons accumulate. That shows high reliability because they are consistent with the hydrocarbon exploration result in this area. On the basis of integrated analyses of source rocks and hydrocarbon migration direction, the following five areas in the gentle slope are identified to be the preferred hydrocarbon accumulation area: Taijiazhuang area, northern and southern Xicaogu area, as well as northern and southern Leijiazhuang area. It is considerably helpful to reduce the risk in hydrocarbon exploration of Shulu Sag.
THE LOWER BOUND OF THE NUMBER OF NON-OVERLAPPING TRIANGLES
Xu, Changqing,Ding, Ren 한국전산응용수학회 2003 Journal of applied mathematics & informatics Vol.11 No.1
Andras Bezdek proved that if a convex n-gon and n points are given, then the points and the sides of the polygon can be renumbered so that at least[${\frac{n}{3}}$] triangles spanned by the ith point and the ith side (i = 1,2,...n) are mutually non-overlapping. In this paper, we show that at least [${\frac{n}{2}}$] mutually non-overlapping triangles can be constructed. This lower bound is best possible.
Wenxuan Hu,Changqing Liu,Wenjun Liu,Xiancheng Ren 한국고분자학회 2018 Macromolecular Research Vol.26 No.5
High-density polyethylene (HDPE) materials were processed into specimens under different processing conditions in this paper. Then specimens were aged under stress and ultraviolet (UV) light in an aging box, and the aging behaviors were studied by means of surface morphology observation, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). It was found that the aging properties of sheath materials were associated with the crystallinity of surface layer. Samples in lower extrusion temperature system and higher extrusion rate had lower surface layer crystallinity and better antiaging properties. In addition, the stress and photo-oxidative aging mechanism were explored. There were two stages in the stress and photo-oxidative aging, which was reflected in the surface layer that crystallinity increased firstly and then decreased. This study may provide better processing conditions for cable sheath materials.
High-Capacity and Robust Watermarking Scheme for Small-Scale Vector Data
( Deyu Tong ),( Changqing Zhu ),( Na Ren ),( Wenzhong Shi ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.12
For small-scale vector data, restrictions on watermark scheme capacity and robustness limit the use of copyright protection. A watermarking scheme based on robust geometric features and capacity maximization strategy that simultaneously improves capacity and robustness is presented in this paper. The distance ratio and angle of adjacent vertices are chosen as the watermark domain due to their resistance to vertex and geometric attacks. Regarding watermark embedding and extraction, a capacity-improved strategy based on quantization index modulation, which divides more intervals to carry sufficient watermark bits, is proposed. By considering the error tolerance of the vector map and the numerical accuracy, the optimization of the capacity-improved strategy is studied to maximize the embedded watermark bits for each vertex. The experimental results demonstrated that the map distortion caused by watermarks is small and much lower than the map tolerance. Additionally, the proposed scheme can embed a copyright image of 1024 bits into vector data of 150 vertices, which reaches capacity at approximately 14 bits/vertex, and shows prominent robustness against vertex and geometric attacks for small-scale vector data.
Pure Ultraviolet Emission from ZnO Quantum Dots-Based/GaN Heterojunction Diodes by MgO Interlayer
Cheng Chen,Renli Liang,Jingwen Chen,Jun Zhang,Shuai Wang,Chong Zhao,Wei Zhang,Jiangnan Dai,Changqing Chen 대한금속·재료학회 2017 ELECTRONIC MATERIALS LETTERS Vol.13 No.4
We demonstrate the fabrication and characterization of ZnO/GaNbasedheterojunction light-emitting diodes (LEDs) by using air-stableand solution-processable ZnO quantum dots (QDs) with a thin MgOinterlayer acting as an electron blocking layer (EBL). The ZnO QDs/MgO/p-GaN heterojunction can only display electroluminescence(EL) characteristic in reverse bias regime. Under sufficient reversebias, a fairly pure ultraviolet EL emission located at 370 nm derivingfrom near band edge of ZnO with a full width at half maximum(FWHM) of 8.3 nm had been obtained, while the deep-level emissionhad been almost totally suppressed. The EL origination andcorresponding carrier transport mechanisms were investigatedqualitatively in terms of photoluminescence (PL) results and energyband diagram.
Structural health monitoring of a high-speed railway bridge: five years review and lessons learned
Ding, Youliang,Ren, Pu,Zhao, Hanwei,Miao, Changqing Techno-Press 2018 Smart Structures and Systems, An International Jou Vol.21 No.5
Based on monitoring data collected from the Nanjing Dashengguan Bridge over the last five years, this paper systematically investigates the effects of temperature field and train loadings on the structural responses of this long-span high-speed railway bridge, and establishes the early warning thresholds for various structural responses. Then, some lessons drawn from the structural health monitoring system of this bridge are summarized. The main context includes: (1) Polynomial regression models are established for monitoring temperature effects on modal frequencies of the main girder and hangers, longitudinal displacements of the bearings, and static strains of the truss members; (2) The correlation between structural vibration accelerations and train speeds is investigated, focusing on the resonance characteristics of the bridge at the specific train speeds; (3) With regard to various static and dynamic responses of the bridge, early warning thresholds are established by using mean control chart analysis and probabilistic analysis; (4) Two lessons are drawn from the experiences in the bridge operation, which involves the lacks of the health monitoring for telescopic devices on the beam-end and bolt fractures in key members of the main truss.
( Qifei Zhou ),( Na Ren ),( Changqing Zhu ),( Deyu Tong ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.7
Most of current watermarking algorithms for GIS vector data embed copyright information by means of modifying the coordinate values, which will do harm to its quality and accuracy. To preserve the fidelity of vector line data and protect its copyright at the same time, a lossless watermarking algorithm is proposed based on storage feature in this paper. Firstly, the superiority of embedding watermark based on storage feature is demonstrated theoretically and technically. Then, the basic concepts and operations on storage feature have been defined including length and angle of the polyline feature. In the process of embedding watermark, the watermark information is embedded into directions of polyline feature by the quantitative mechanism, while the positions of embedding watermark are determined by the feature length. Hence, the watermark can be extracted by the same geometric features without original data or watermark. Finally, experiments have been conducted to show that coordinate values remain unchanged after embedding watermark. Moreover, experimental results are presented to illustrate the effectiveness of the method.
An Adaptive Watermark Detection Algorithm for Vector Geographic Data
( Yingying Wang ),( Chengsong Yang ),( Na Ren ),( Changqing Zhu ),( Ting Rui ),( And Dong Wang ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.1
With the rapid development of computer and communication techniques, copyright protection of vector geographic data has attracted considerable research attention because of the high cost of such data. A novel adaptive watermark detection algorithm is proposed for vector geographic data that can be used to qualitatively analyze the robustness of watermarks against data addition attacks. First, a watermark was embedded into the vertex coordinates based on coordinate mapping and quantization. Second, the adaptive watermark detection model, which is capable of calculating the detection threshold, false positive error (FPE) and false negative error (FNE), was established, and the characteristics of the adaptive watermark detection algorithm were analyzed. Finally, experiments were conducted on several real-world vector maps to show the usability and robustness of the proposed algorithm.