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Search Results: 1 - 10 of 4948 matches for " Lai Fengxiang "
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Chaos Synchronization of Uncertain Lorenz System via Single State Variable Feedback  [PDF]
Fengxiang Chen, Tong Zhang
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.411A2002

This paper treats the problem of chaos synchronization for uncertain Lorenz system via single state variable information of the master system. By the Lyapunov stability theory and adaptive technique, the derived controller is featured as follows: 1) only single state variable information of the master system is needed; 2) chaos synchronization can also be achieved even if the perturbation is occurred in some parameters of the master chaotic system. Finally, the effectiveness of the proposed controllers is also illustrated by the simulations as well as rigorous mathematical proofs.

Non-Noether conserved quantity for differential equations of motion in the phase space
Fengxiang Mei
Chinese Science Bulletin , 2002, DOI: 10.1360/02tb9443
Abstract: A non-Noether conserved quantity for the differential equations of motion of mechanical systems in the phase space is studied. The differential equations of motion of the systems are established and the determining equations of Lie symmetry are given. An existence theorem of non-Noether conserved quantity is obtained. An example is given to illustrate the application of the result.
Lie symmetry and conservation law of Birkhoffian system
Fengxiang Mei
Chinese Science Bulletin , 1999, DOI: 10.1007/BF02885481
Abstract: The Lie symmetry of Birkhoffian system was studied, the condition under which the system admits the one-parameter Lie group of transformation with infinitesimal generator was given, and the structural equation and the conservation law of the system was obtained.
Inhibitory Effect of α-Pinene on SGC-7901 Cell Proliferation and the Mechanism of ATM Kinase Signaling Pathway  [PDF]
Fuhong Zhu, Fengxiang Wei, Cui Zhang
Chinese Medicine (CM) , 2015, DOI: 10.4236/cm.2015.61004

Objective: To research the inhibitory effect on SGC-7901 cells of α-pinene, and the related mechanism of α-pinene. Methods: Used the MTT method to detect inhibition rate and western blotting to detect the influence on expression of ATM, Phos-S1981ATM, H2AX, γH2AX, CHK2 and p-CHK2, p53 and phos-p53 cell cycle related protein in SGC-7901 cells. Results: The research found α-pinene could inhibit the proliferation of SGC-7901 cells observably in vitro, and the inhibition rate assumes the dependence on concentration; and western blotting results showed that, α-pinene could activate phospho-ATM, increase the amount of γH2AX (p < 0.05, p < 0.05); increase the expression of p-CHK2, p53 and phos-p53 (p < 0.05, p

Calibration of Car-Following Models Considering the Impacts of Warning Messages from Tablet/Smartphone Application  [PDF]
Qing Li, Fengxiang Qiao, Lei Yu
Journal of Transportation Technologies (JTTs) , 2016, DOI: 10.4236/jtts.2016.62006
Abstract: The phenomenon of car-following is special in traffic operations. Traditional car-following models can well describe the reactions of the movements between two concessive vehicles in the same lane within a certain distance. With the invention of connected vehicle technologies, more and more advisory messages are in development and applied in our daily lives, some of which are related to the measures and warnings of speed and headway distance between the two concessive vehicles. Such warnings may change the conventional car-following mechanisms. This paper intends to consider the possible impacts of in-vehicle warning messages to improve the traditional car-following models, including the General Motor (GM) Model and the Linear (Helly) Model, by calibrating model parameters using field data from an arterial road in Houston, Texas, U.S.A. The safety messages were provided by a tablet/smartphone application. One exponent was applied to the GM model, while another one applied to the Linear (Helly) model, both were on the stimuli term “difference in velocity between two concessive vehicles”. The calibration and validation were separately conducted for deceleration and acceleration conditions. Results showed that, the parameters of the traditional GM model failed to be properly calibrated with the interference of in-vehicle safety messages, and the parameters calibrated from the traditional Linear (Helly) Model with no in-vehicle messages could not be directly used in the case with such messages. However, both updated models can be well calibrated even if those messages were provided. The entire research process, as well as the calibrated models and parameters could be a reference in the on-going connected vehicle program and micro/macroscopic traffic simulations.
Drivers’ Reaction of Warning Messages in Work Zone Termination Areas with Left Turn  [PDF]
Boya You, Fengxiang Qiao, Lei Yu
Journal of Transportation Technologies (JTTs) , 2016, DOI: 10.4236/jtts.2016.63013
Abstract: Work-zone crashes have always drawn public attention. A number of fatalities are recorded every year nationwide within work zone areas. Most existing countermeasures have been dedicated more to the advance warning areas, transition areas, and activity areas of work zone, than the termination areas, where drivers might play less attention to safety threats. In this study, the vehicle-to-vehicle communication based left turn warning system was applied at a work zone termination area, which is immediately followed by a T-intersection. The work-zone is located on the minor road side, while left turn vehicles will be appearing from the major street through the said T-intersection. A smart phone application was designed using Android coding system to provide several types of warning messages to drivers. Corresponding scenarios were designed in a driving simulator, and 20 subjects were recruited to participate in the simulation test followed by a questionnaire survey. The subjects received a warning message when driving to the termination area of a work zone on the coming left turn vehicles. Twenty test drivers’ driving speed, acceleration rates, and break reaction distance to the warning messages were studied in four different scenarios. Results show that the smartphone application has a great impact on driving behaviors, especially the female voice and the beep tone warning, which are recommended for possible field tests. Besides, the developed smartphone applications can be further updated for practical applications of similar needs.
The effects of rice growth stages on the ovarian development and take-off of Nilaparvata lugens and Sogatella furcifera

CHEN Yu,FU Qiang,LAI Fengxiang,LUO Ju,ZHANG Zhitao,HU Guowen,

生态学报 , 2012,
Abstract: The brown planthopper(Nilaparvata lugens(Stl)) and white-backed planthopper(Sogatella furcifera(Horváth)) represent two of the most important insect pests of rice in Asia,causing severe damage to rice production.Both belong to long-distance migratory insects but differ in the time when they reach maximum density during rice-growing season.S.furcifera generally reaches its peak of occurrence when rice is before the filling stage;while N.lugens reaches its peak at the rice filling stage.It is possible that the same rice stage might impact the two planthopper species differently,thus leading to such a seasonal difference in population growth.To test this,we inoculated newly-emerged adults onto rice plants at each of the three developmental stages,i.e.,early tillering stage(about 40-d old,with 2—3 tillers),jointing stage(about 60-d old,the longest internode < 2 cm) and booting-to-heading stage(about 75-80-d old).The level of ovarian development and take-off rate were then measured daily from the 2nd to the 5th day and from the 1st to the 5th day after emergency,respectively.Ovarian development from 2nd to the 5th day was largely dominated by grade Ⅰ,Ⅱ,Ⅲ and Ⅳ,respectively,with three exceptions including the 4d-(dominated by grade Ⅱ) and 5d-old S.furcifera females(grade Ⅲ) at booting-to-heading stage plants,plus the 5d-old S.furcifera females(grade Ⅲ) at jointing stage plants.For ovarian development in N.lugens females,in vast majority of the cases the three rice stages showed comparable proportion of females at each of the detected ovarian development grades,we only observed significant difference between early tillering stage(73.2% of the females at grade Ⅳ) and booting-to-heading stage(89% at grade Ⅳ) on the 5th day.In contrast,the grade of ovarian development displayed much larger differences among the three rice stages for both 4d-and 5d-old S.furcifera females.In particular,over 86% of the females from rice early tillering stage developed into grade Ⅲ on the 4th day and into grade Ⅳ on the 5th day,versus less than one quarter of the females from the booting-to-heading stage.To a similar extent,the ratio of females at grade Ⅲ was 4.2:1 between jointing stage and booting-to-heading stage on the 4th day,along with a ratio of up to 6.8:1 between early tillering stage and jointing stage for the 5d-old females at grade Ⅳ.As for the take-off rate,while little variation was seen for N.lugens across the three rice stages,noticeable differences were revealed for 1d-,4d-and 5d-old S.furcifera adults,with early tillering stage being constantly associated with the lowest take-off rate and booting-to-heading stage with the highest take-off rate.Thus,our results demonstrated a profound effect on the development of S.furcifera by a change of rice stage,as compared to relatively limited effect on N.lugens development.Furthermore,among the three rice stages,early tillering stage is most favorable and booting-to-heading stage is least favorable for S.furcifera de
First integral and integral invariant of Birkhoffian system
Fengxiang Mei,Huibin Wu
Chinese Science Bulletin , 2000, DOI: 10.1007/BF02884939
Abstract: The variational equation of the Birkhoffian system is established, by which it is proved that an integral invariant can be constructed with a known first integral. And its inverse is also correct.
Lie symmetries of mechanical systems with unilateral holonomic constraints
Yi Zhang,Fengxiang Mei
Chinese Science Bulletin , 2000, DOI: 10.1007/BF02886235
Abstract: In the recent twenty years, the study on the Lie symmetries and conserved quantities of constrained mechanical systems has been making great progress[1–5]. Up to now, however, all the studies are limited to the mechanical systems with ideal bilateral constraints. This note further studies the Lie symmetries of mechanical systems with unilateral holonomic constraints, and two problems of Lie symmetries for the systems are put forward and solved, i.e. finding the conserved quantity from a Lie symmetric transformation of the system and finding the corresponding Lie symmetry from an integral of the system.
Lie symmetry and conservation law of Birkhoffian system

Fengxiang Mei,

科学通报(英文版) , 1999,
Abstract: The Lie symmetry of Birkhoffian system was studied, the condition under which the system admits the one-parameter Lie group of transformation with infinitesimal generator was given, and the structural equation and the conservation law of the system was obtained.
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