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Improvement, Comparison, and Application of Field Measurement Methods for Grassland Vegetation Fractional Coverage

Journal of Integrative Plant Biology 2005年第9期47卷 1074-1083页

作者： xiao-Bing LI yun-Hao CHEN Hua YANG yun-xia ZHANG College of Resources Sciences and Technology Key Laboratory of Environmental Change and Natural Disaster of the Ministry of Education Beijing Normal University Beijing 100875 China

As one of the important vegetation parameters, vegetation fractional coverage （VFC） is more difficult to measure accurately among a good many parameters of plant communities. The temperate typical steppe in the north of China was chosen for investigation in the present study and a digital camera was used to measure herb community coverage in the field, adopting methods of ocular estimation, gridding measurement, visual interpretation, supervised classification, and information extraction of color spatial transformation to calculate the VFC of images captured by the digital camera. In addition VFC calculated by various methods was analyzed and compared VFC, enabling us to propose an effective method for measuring VFC using a digital camera. The results of the present study indicate that：（i） as two common useful and effective methods of measuring VFC with a digital camera, not only does the error of estimated values of visual estimation and supervised classification vary considerably, but the degree of automatization is very low and depends, to a great extent, on the manipulator; （ii） although the method of visual interpretation may assure the precision of the calculated VFC and enable the precision of results obtained using other methods to be determined, as far as large quantities of data are concerned, this method has the disadvantages of wasting time and energy, and the applications of this method are limited; （iii） the precision and stability of VFC calculated using the grid and node method are superior to those of visual estimation and supervised classification and inferior to those of visual interpretation, but, as for visual interpretation and supervised classification, gridding measurements are difficult to apply in practice because they are not time efficient; and （iv） in terms of the precision of calculation of the VFC, an information-extracting model based on an intensity, hue, saturation （IHS） color space-multi-component series segmentation strategy is s

关键词： color space transformation digital camera field measurement grassland vegetationfractional coverage.

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Theoretical Study of Reaction Mechanism of 1-Propenyl Radical with NO

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Chinese Journal of Chemical Physics 2008年第3期21卷 239-244页

作者： Xue-li Cheng Yan-yun Zhao Feng Li ren-tao Wu Department of Chemistry Taishan University Tai'an 271021 China Department of Chemistry Qufu Normal University Qufu 273155 China Department of Physics Taishan University Tai'an 271021 China

The reaction system of 1-propenyl radical with NO is an ideal model for studying the intermolecular and intramolecular reactions of complex organic free radicals containing C=C double bonds. On the basis of the full optimization of all species with the Gaussian 98 package at the B3LYP/6- 311＋＋G^＊＊ level, the reaction mechanism was elucidated extensively using the vibrational mode analysis. There are seven reaction pathways and five sets of small molecule end products： CH2O＋CH3CN, CH2CHCN＋H2O, CH3CHO＋HCN, CH3CHO＋HNC, and CH3CCH＋HNO. The channel of C3H5-＋NO→IM1→TS1→IM2→TS2→IM3→TS3→CH3CHO＋HCN is thermodynamically most favorable.

关键词： Reaction mechanism 1-Propenyl radical NO Vibrational mode analysis

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Study of Squeezed Excitons in Polar Semiconductors

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Communications in Theoretical Physics 2009年第3期51卷 545-549页

作者： YIN Miao CHENG Ze WU Zi-xia PING yun-xia Department of Physics Huazhong University of Science and Technology Wuhan 430074 China

Some properties of excitons in polar semiconductors are studied theoretically by means of squeezed state variational approach. This method makes it possible to consider bilinear terms of the phonon operators as well as linear terms arising from the Lee-Low-Pines （LLP）-like transformation. The exciton ground state energy and binding energy are calculated numerically. It is shown that the squeezing effect is significant in the case of strong exciton-phonon coupling region.

关键词： squeezed exciton electron-phonon interaction binding energy

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Numerical Study on Motion Responses of Two Parallel Ships During Underway Replenishment by the Semi-Analytical HOTP Method

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China Ocean Engineering 2022年第2期36卷 233-246页

作者： YANG yun-tao ZHU ren-chuan MA Chao GAO Hui School of Naval Architecture and Civil Engineering Jiangsu University of Science and TechnologyZhangjiagang 215600China State Key Laboratory of Ocean Engineering Collaborative Innovation Center for Advanced Ship and Deep-Sea ExplorationSchool of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China Key Laboratory of High Performance Ship Technology(Wuhan University of Technology) Ministry of EducationWuhan 430063China School of Naval Architecture Ocean and Energy Power EngineeringWuhan University of TechnologyWuhan 430063China

Motion responses of two ships advancing parallel in waves with hydrodynamic interactions are investigated in this paper. Within the framework of the frequency-domain potential flow theory, a semi-analytical higher-order translating-pulsating source(HOTP) method is presented to solve the problems of coupled radiation and diffraction potential. The method employs nine-node bi-quadratic curvilinear elements to discretize the boundary integral equations(BIEs) constructed over the mean wetted surface of the two ship hulls. In order to eliminate the numerical oscillation, analytical quadrature formulas are derived and adopted to evaluate the integrals related to the Froudedependent part of the Green’s function along the horizontal direction in the BIEs. Based on the method, a numerical program is originally coded. Through the calculations of hydrodynamic responses of single ships, the numerical implementation is proved successful. Then the validated program is applied in the investigations on the hydrodynamic interactions of two identical Wigley Ⅲ hulls and the underway replenishment of a frigate and a supply ship in waves with and without stagger, respectively. The comparison between the present computed results with experimental data and numerical solutions of other methods shows that the semi-analytical HOTP method is of higher accuracy than the pulsating source Green’s function method with speed correction and better stability than the traditional HOTP method based on Gauss quadrature. In addition, for two ships with obviously different dimensions,the influence of hydrodynamic interactions on the smaller ship is found to be more noticeable than that on the larger ship, which leads to the differences between the motions of frigate with and without the presence of supply ship.

关键词： semi-analytical HOTP method two parallel ships underway replenishment coupled motions

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Solventless ketalization of glycerol to solketal with acetone over the ionic liquid[P(C4H9)3C14H29][TsO]

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Chinese Journal of Chemical Engineering 2020年第1期28卷 158-164页

作者： Yu Ji Tengda Zhang xia Gui Haijian Shi Zhi yun College of Chemistry and Chemical Engineering Nanjing Tech UniversityNanjing 210009China

The ketalization of glycerol with acetone was conducted over an ionic liquid[P(C4H9)3C14H29][TsO](TTPT)in a batch reactor.A scheme to obtain the purified product using TTPT as a homogeneous catalyst is proposed and a maximum solketal yield of 86%is achieved at acetone/glycerol molar ratio of 6/1,reaction time of 0.5 h,reaction temperature of 303 K,catalyst amount of 5 wt%of *** was recycled and reused for ten times without obvious losses in terms of quantity and ***,effects of various experimental parameters(stirring speed,catalyst loadings,temperature and reactant composition)on the reaction kinetics are *** terms of kinetics modeling,Kγis fitted by reactant composition at the temperature range 298 K–323 K,which was a concise strategy that showed good precision in the kinetics *** activation energy for this ketalization reaction was evaluated to be 28.2 kJ·mol^-*** addition,the kinetics of the reaction at a temperature exceeding the boiling point of acetone were also *** believe that all the results are important for further development of a technology for the continuous synthesis of solketal.

关键词： Ionic liquid Ketalization Solketal Glycerol Reaction kinetics Reactive distillation

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Consistency and Asymptotic Normality of the Maximum Quasi-likelihood Estimator in Quasi-likelihood Nonlinear Models with Random Regressors

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Acta Mathematicae Applicatae Sinica 2010年第2期26卷 241-250页

作者： Tian xia Shun-fang Wang Xue-ren Wang Department of Statistics Yunnan University Kunming 650091 China School of Information Science and Engineering Yunnan University Kunming 650091 China

This paper proposes some regularity conditions, which result in the existence, strong consistency and asymptotic normality of maximum quasi-likelihood estimator （MQLE） in quasi-likelihood nonlinear models （QLNM） with random regressors. The asymptotic results of generalized linear models （GLM） with random regressors are generalized to QLNM with random regressors.

关键词： Asymptotic normality consistency maximum quasi-likelihood estimator quasi-likelihood nonlinear models with random regressors

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A power fluctuation evaluation method of PV plants based on RankBoost ranking

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Protection and Control of Modern Power Systems 2021年第1期6卷 347-356页

作者： Weiyi xia Zhouyang ren Hui Li Bo Hu The State Key Laboratory of Power Transmission Equipment&System Security and New Technology School of Electrical EngineeringChongqing UniversityChongqing400044PR China

Fluctuation evaluation is an important task in promoting the accommodation of photovoltaic (PV) power generation. This paper proposes an evaluation method to quantify the power fluctuation of PV plants. This consists of an index system and a ranking method based on the RankBoost algorithm. Eleven indices are devised and included in the index system to fully cover diverse fluctuation features. By handling missing and invalid data effectively, the ranking method fuses multiple indices automatically and provides a systematic and comprehensive comparison of power fluctuation. Simulation results based on power data from six PV plants indicate that the evaluation list obtained by the RankBoost ranking method is better represented and more comprehensive than that derived by the equal weight method.

关键词： Fluctuation evaluation Photovoltaic power RankBoost ranking algorithm

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Ground Nephogram Recognition Algorithm Based on Selective Neural Network Ensemble

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Computers, Materials & Continua 2020年第5期63卷 621-631页

作者： Tao Li xiang Li Yongjun ren Jinyue xia College of Electronic and Information Engineering Nanjing University of Information Science and TechnologyNanjing210044China College of Computer and Software Nanjing University of Information Science and TechnologyNanjing210044China International Business Machines Corporation(IBM) New YorkUSA

In view of the low accuracy of traditional ground nephogram recognition model,the authors put forward a k-means algorithm-acquired neural network ensemble method,which takes BP neural network ensemble model as the basis,uses k-means algorithm to choose the individual neural networks with partial diversities for integration,and builds the cloud form classification *** simulation experiments on ground nephogram samples,the results show that the algorithm proposed in the article can effectively improve the Classification accuracy of ground nephogram recognition in comparison with applying single BP neural network and traditional BP AdaBoost ensemble algorithm on classification of ground nephogram.

关键词： Cloud shape k-means BP neural network adaboost

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A new test on the conditional capital asset pricing model

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Applied Mathematics(A Journal of Chinese Universities) 2015年第2期30卷 163-186页

作者： LI xia-fei CAI Zong-wu ren Yu Wang Yanan Institute for Studies in Economics The MOE Key Lab of Econometrics and Fujian Key Lab of Statistical Sciences Xiamen University Department of Economics University of Kansas

Testing the validity of the conditional capital asset pricing model （CAPM） is a puzzle in the finance literature. Lewellen and Nagel[14] find that the variation in betas and in the equity premium would have to be implausibly large to explain important asset-pricing anomalies. Unfortunately, they do not provide a rigorous test statistic. Based on a simulation study, the method proposed in Lewellen and Nagel[14] tends to reject the null too frequently. We develop a new test procedure and derive its limiting distribution under the null hypothesis. Also, we provide a Bootstrap approach to the testing procedure to gain a good finite sample performance. Both simulations and empirical studies show that our test is necessary for making correct inferences with the conditional CAPM.

关键词： Asset pricing model bootstrap test conditional CAPM large sample theory

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Complete oxidation of ethanol over vanadium based catalysts

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Journal of Natural Gas Chemistry 2009年第3期18卷 379-382页

作者： Zhe Li xia An Panjie ren Wei Huang Kechang Xie Key Laboratory of Coal Science and Technology of Ministry of Education Taiyuan University of Technology Taiyuan 030024 China

V2O5/γ-Al2O3-TiO2 catalysts were prepared by the mixing sol-gel and co-impregnation method. The performance of the catalysts for complete oxidation of ethanol was evaluated in a conventional fixed-bed quartz reactor. And the effects of support, preparation methods and vanadium content have been investigated. The results showed that 5% V2O5 catalyst supported on γ-Al2O3-TiO2 possessed the best ethanol conversion under the considered temperature. This may be ascribed to the highly dispersible active component, mutual function between the active component and the carriers. The nature of the best performance for 5%V/γ-Al2O3-TiO2 catalyst may be related to the high V4＋ amounts on the surface. And the surface V4＋ species may play an important role in the formation of active site for the total ethanol oxidation.

关键词： ethanol γ-Al2O3-TiO2 V2O5 catalytic oxidation

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