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Search Results: 1 - 10 of 159661 matches for " WANG Zheng-feng "
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Plant conservation genetics
植物保护遗传学

WANG Zheng-Feng,
王峥峥

生态学报 , 2003,
Abstract: The goal of conservation biology is to conserve global biodiversity. In order to accomplish this monumental task, the field of conservation biology must be multi-disciplinary; one of its essential disciplines is conservation genetics. Author consider two aspects of conservation genetics: (1) population genetic issues relating to the maintenance of genetic variability, avoiding inbreeding and outbreeding depression, and using genetic markers for conservation, and (2) systematic issues relating to the recogni...
Symbolic transfer entropy-based premature signal analysis

Wang Jun,Yu Zheng-Feng,

中国物理 B , 2012,
Abstract: In this paper, we use symbolic transfer entropy to study the coupling strength between premature signals. Numerical experiments show that three types of signal couplings are in the same direction. Among them, normal signal coupling is the strongest, followed by that of premature ventricular contractions, and that of atrial premature beats is the weakest. The T test shows that the entropies of the three signals are distinct. Symbolic transfer entropy requires less data, can distinguish the three types of signals and has very good computational efficiency.
Analysis of Hedging Profits Under Two Stock Pricing Models  [PDF]
Lingyan Cao, Zheng-Feng Guo
Journal of Mathematical Finance (JMF) , 2011, DOI: 10.4236/jmf.2011.13015
Abstract: In this paper, we employ two stock pricing models: a Black-Scholes (BS) model and a Variance Gamma (VG) model, and apply the maximum likelihood method (MLE) to estimate corresponding parameters in each model. With the estimated parameters, we conduct Monte Carlo simulations to simulate spot prices and deltas of the European call option at different time spots over different sample paths. We focus on calculating the deltas for the two models by the method of the in?nitesimal perturbation analysis (IPA). Then, we-nally, hedging profits under these two models are calculated and analyzed.
MR Imaging of Patients with Lateral Epicondylitis of the Elbow: Is the Common Extensor Tendon an Isolated Lesion?
Liang Qi, Zheng-Feng Zhu, Feng Li, Ren-Fa Wang
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0079498
Abstract: Objective To investigate whether an injury of the common extensor tendon (CET) is associated with other abnormalities in the elbow joint and find the potential relationships between these imaging features by using a high-resolution magnetic resonance imaging (MRI). Methods Twenty-three patients were examined with 3.0 T MR. Two reviewers were recruited for MR images evaluation. Image features were recorded in terms of (1) the injury degree of CET; (2) associated injuries in the elbow joint. Spearman’s rank correlation analysis was performed to analyze the relationships between the injury degree of CET and associated abnormalities of the elbow joint, correlations were considered significant at p<0.05. Results Total 24 elbows in 23 patients were included. Various degrees of injuries were found in total 24 CETs (10 mild, 7 moderate and 7 severe). Associated abnormalities were detected in accompaniments of the elbow joints including ligaments, tendons, saccussynovialis and muscles. A significantly positive correlation (r = 0.877,p<0.01) was found in injuries of CET and lateral ulnar collateral ligament (LUCL). Conclusion Injury of the CET is not an isolated lesion for lateral picondylitis, which is mostly accompanied with other abnormalities, of which the LUCL injury is the most commonly seen in lateral epicondylitis, and there is a positive correlation between the injury degree in CET and LUCL.
Implemention of Multicast Based on Vlan in Lay3 Switch
三层交换机基于vlan的组播实现

WANG Jian-Wen,WANG Zheng-Feng,
王建文
,王政锋

计算机系统应用 , 2010,
Abstract: This paper describes the support for multicast and vlan(virtual LAN) on bcm5695 switch chip , analyzes the advantage of lay3 switch comparing router on LAN, discusses and resolves the difficulty of routing on vlan through hardware address table, and presents the implemention of software.
Derivation of a Nonlinear Reynolds Stress Model Using Renormalization Group Analysis and Two-Scale Expansion Technique
LIU Zheng-Feng,WANG Xiao-Hong,
刘正锋
,王晓宏

中国物理快报 , 2008,
Abstract: Adopting Yoshizawa's two-scale expansion technique, the fluctuating field is expanded around the isotropic field. The renormalization group method is applied for calculating the covariance of the fluctuating field at the lowerorder expansion. A nonlinear Reynolds stress model is derived and the turbulent constants inside are evaluated analytically. Compared with the two-scale direct interaction approximation analysis for turbulent shear flows proposed by Yoshizawa, the calculation is much more simple. The analytical model presented here is close to the Speziale model, which is widely applied in the numerical simulations for the complex turbulent flows.
The dispersive properties of an excited-doublet four-level atomic system

Hu Zheng-Feng,Deng Jian-Liao,Wang Yu-Zhu,

中国物理 B , 2008,
Abstract: We have investigated the dispersive properties of excited-doublet four-level atoms interacting with a weak probe field and an intense coupling laser field. We have derived an analytical expression of the dispersion relation for a general excited-doublet four-level atomic system subject to a one-photon detuning. The numerical results demonstrate that for a typical rubidium $\rm {D1}$ line configuration, due to the unequal dipole moments for the transitions of each ground state to double excited states, generally there exists no exact dark state in the system. Close to the two-photon resonance, the probe light can be absorbed or gained and propagate in the so-called superluminal form. This system may be used as an optical switch.
Nonparametric Lag Selection for Additive Models based on the Smooth Backfitting Estimator  [PDF]
Zheng-Feng Guo, Lingyan Cao, Ying He
Theoretical Economics Letters (TEL) , 2011, DOI: 10.4236/tel.2011.12004
Abstract: This paper proposes a nonparametric FPE-like procedure based on the smooth backfitting estimator when the additive structure is a priori known. This procedure can be expected to perform well because of its well-known finite sample performance of the smooth backfitting estimator. Consistency of our procedure is established under very general conditions, including heteroskedasticity.
Multimode Coupling Theory for Kelvin-Helmholtz Instability in Incompressible Fluid

WANG Li-Feng,YE Wen-Hua,FAN Zheng-Feng,LI Ying-Jun,

中国物理快报 , 2009,
Abstract: A weakly nonlinear model is proposed for multimode Kelvin-Helmholtz instability. The second-order mode coupling formula for Kelvin-Helmholtz instability in two-dimensional incompressible fluid is presented by expanding the perturbation velocity potential to second order. It is found that there is an important resonance in the course of the sum frequency mode coupling but the difference frequency mode coupling does not have. This resonance makes the sum frequency mode coupling process relatively complex. The sum frequency mode coupling is strongly dependent on time especially when the density of the two fluids is adjacent and the difference frequency mode coupling is not.
Study on the Kelvin-Helmholtz instability in two-dimensional incompressible fluid
二维不可压流体Kelvin-Helmholtz不稳定性的弱非线性研究

Wang Li-Feng,Ye Wen-Hu,Fan Zheng-Feng,Li Ying-Jun,
王立锋
,叶文华,范征锋,李英骏

物理学报 , 2009,
Abstract: A weakly nonlinear model is proposed for the Kelvin-Helmholtz instability by expanding the perturbation velocity potential to third order. It is found that there is an important resonance in the process of mode coupling. This resonance makes the coupling processes very complex and interesting. Single-mode perturbation enters nonlinear stage quickly and produces lots of harmonics. The resonance reinforces the action of nonlinear process. The second and third harmonic generation efficiency of a single-mode disturbance is computed, as well as the nonlinear correction to the exponential growth of the fundamental modulation. Our simulations support the weakly nonlinear results from our analytic model. The nonlinear threshold phenomenon is also analyzed.
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