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Estimation in partially linear time-varying coefficients panel data models with fixed effects
Jing Zhao,Sanying Feng,Weihu Cheng 한국통계학회 2017 Journal of the Korean Statistical Society Vol.46 No.2
A partially time-varying coefficient time series panel data model with fixed effects is considered to characterize the nonlinearity and trending phenomenon in panel data model. To estimate the linear regression coefficient and the time-varying coefficient function, two methods are applied with the help of profile least squares. The first one is taking cross-sectional average to eliminate the fixed effects. The second one is local linear dummy variable approach. In each method we derive consistent estimates for both the parametric component and non-parametric trend function. The asymptotic distributions of the estimates are established when T and N tend to infinity simultaneously, where N is the cross section size, T is the time series length. The asymptotic results reveal that the parametric component (non-parametric coefficient function) estimate based on crosssectional average has a rate of convergence T)^−1/2 ((Th)^−1/2) that is slower than that based on local linear dummy variable approach, which is (NT))^−1/2((NTh)^−1/2), where h is the bandwidth. Furthermore, block bootstrap method is used to construct confidence interval for parametric and nonparametric components, respectively. At last, some simulation studies are conducted to examine the finite sample performance for the proposed methods and a real data example is analyzed.
Cytotoxic Components in an Extract from the Leaves and Stems of Stauntonia hexaphylla
Jing Zhao,임순호,이익수,엄중인,박시환,오은상,정다운,다런윌리엄스 한국생약학회 2014 Natural Product Sciences Vol.20 No.2
An investigation was carried out to identify novel anti-cancer compounds from Korean indigenous plant extracts. Bioassay-guided fractionation and chemical investigation of the EtOAc extract from the leaves and stems of Stauntonia hexaphylla resulted in the isolation of two active compounds, hederagenin 3-O-a-L-arabinoside (1) and quercetin (2). The structures of these compounds were elucidated by spectroscopic methods, including UV, IR, MS, NMR techniques and compared with previous spectroscopic data. The cytotoxic effects of fractions and compounds on HCT116 human colon cancer cells were evaluated using the MTT assay. Quercetin showed a stronger anti-cancer effect when compared to hederagenin 3-O-a-L-arabinoside.
Jing Zhao,Pak Kin Wong,Zhengchao Xie,Xinbo Ma,Xingqi Hua 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.1
The semi-active suspension (SAS) system has been one of the most attractive topics due to its simplicity and effectiveness in the control of vehicle dynamics. This research proposes a cuckoo search optimized proportional-integral– derivative (CS-PID) strategy for the damping force control of the semi-acive suspension system in order to improve vehicle ride quality. Firstly, a quarter-car suspension model with air spring and variable hydraulic damper (VHD) is developed. By constructing the detailed analytical model and describing the working process, the regulating mechanism and external characteristics of the VHD are presented. Subsequently, the CS-PID strategy is designed to generate the desired damping force according to the vehicle states in real-time, followed with the evaluation of the proposed strategy. Finally, the experimental tests are carried out to verify the accuracy of the VHD model and examine the feasibility of the proposed strategy. The numerical simulation reveal that the proposed control strategy is effective in improving the vehicle performance and the experimental results show that the CS-PID strategy can be successfully implemented in the suspension system for practical use.
Fragrance Composition in Six Tree Peony Cultivars
Jing Zhao,Zeng-hui Hu,Ping-sheng Leng,Hui-xiu Zhang,Fang-yun Cheng 한국원예학회 2012 원예과학기술지 Vol.30 No.6
Tree peony is a traditional famous flower of China, and plays an important role in Chinese traditional culture. But the floral scent of tree peony in vivo is little known. In this study, in order to explore the floral composition of tree peony, floral volatiles of six cultivars, including Paeonia suffruticosa ‘Zhaofen’ (ZF), P. suffruticosa ‘Luoyanghong’ (LYH), P. ostii ‘Fengdanbai’ (FDB), P. × lemonei ‘High noon’ (HN), P. × lemonei ‘Renown’ (R), and P. rockii ‘Gaoyuanshenghuo’ (GYSH) were collected by dynamic headspace and then identified by Automated Thermal Desorption-Gas Chromatography/Mass Spectometry. The results showed that floral fragrances of the six cultivars were qualitatively and quantitatively distinct. A total of 105 volatiles involving ten categories were detected. But not all volatile categories were emitted from these cultivars. The six peony cultivars emitted some shared compounds and peculiar compounds. The total released amounts of volatiles emitted from six cultivars were found significantly different, which was greatest for ‘GYSH’. The most abundant volatile compounds detected from ‘ZF’, ‘LYH’, ‘FDB’, ‘HN’, ‘R’, and ‘GYSH’ were respectively α-pinene, 2,3-dihydroxy propanal, 3-methyl-1-butanol, 2-ethyl-1-hexanol, acetic acid 1-methylethyl ester, and 5-ethyl-2,2,3-trimethyl heptane. This result may contribute to exploring the biosynthesis and emission mechanism of floral scent in tree peony.
Decoupling Control Analysis of a Flux Reversal Linear Rotary Permanent Magnet Actuator
Kaikai Guo,Youguang Guo,Jingzhao Li 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.4
In order to meet the requirement of industrial production, a control system of a novel fux reversal linear rotary permanent magnet actuator (FR-LRPMA) is developed in this paper, and the electromagnetic and motion decoupled process is analyzed in detail. Firstly, the control equation of FR-LRPMA is derived in the nine phase stator coordinate system and dual dq-axis mover coordinate system. Then the control model of FR-LRPMA is built in MATLAB/Simulink using improved space vector pulse width modulation (SVPWM), and the linear, rotary and spiral motions of the proposed actuator are achieved. Finally, the prototype of the actuator is manufactured, and the experiment platform of FR-LRPMA is set up to measure the cogging torque and linear detent force, validating the simulation results. It is concluded that the control system of FR-LRPMA can be converted into two independent single freedom motors by dual dq transformation. The improved SVPWM is efective in the control system, and the method can be used to solve the electromagnetic and motion decoupling problems.
A CLASS OF NONMONOTONE SPECTRAL MEMORY GRADIENT METHOD
Zhensheng Yu,Jinsong Zang,Jingzhao Liu 대한수학회 2010 대한수학회지 Vol.47 No.1
In this paper, we develop a nonmonotone spectral memory gradient method for unconstrained optimization, where the spectral stepsize and a class of memory gradient direction are combined efficiently. The global convergence is obtained by using a nonmonotone line search strategy and the numerical tests are also given to show the efficiency of the proposed algorithm.
A CLASS OF NONMONOTONE SPECTRAL MEMORY GRADIENT METHOD
Yu, Zhensheng,Zang, Jinsong,Liu, Jingzhao Korean Mathematical Society 2010 대한수학회지 Vol.47 No.1
In this paper, we develop a nonmonotone spectral memory gradient method for unconstrained optimization, where the spectral stepsize and a class of memory gradient direction are combined efficiently. The global convergence is obtained by using a nonmonotone line search strategy and the numerical tests are also given to show the efficiency of the proposed algorithm.