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Partial Shade Optimizes Photosynthesis and Growth in Bayberry (Myrica rubra) Trees
Guanghui Zeng,Yanping Guo,Jianxu Xu,Meijun Hu,Jie Zheng,Zhenwang Wu 한국원예학회 2017 Horticulture, Environment, and Biotechnology Vol.58 No.3
This study investigates the effects of radiation heat-load reduction under different shading conditions on thegrowth of three-year-old bayberry (Myrica rubra) trees from 1 July through 31 October 2007 in the Zhejiang Province,a warm subtropical region of China. The trees were grown under direct sunlight (control) and under 25%, 50%, and75% shading conditions using black plastic nets. Stomatal conductance and photosynthesis were greatest under 50%shading, as were plant height and leaf and root dry weights. Twenty-five percent shading did not significantly influenceplant height or root and leaf dry weights, whereas 75% shading resulted in a decrease in root and leaf dry weightswhen compared with the controls. The photochemical efficiency and electron transport of PSII increased under shadedconditions due to an increase in D1 protein. The concentrations of chlorophyll a and b and the total chlorophyllcontent in leaves were increased in plants grown under 25% and 50% shading, but reduced in those grown under75% shading. Under 50% shading, growth and biomass increased due to increased photosynthesis, which resulted fromdecreased photodamage and increased chlorophyll concentration. These data show that 50% shading promotes optimalgrowth in bayberry plants.
Effect of SiO2 additives on the microstructure and energy storage density of SrTiO3 ceramics
Guanghui Zhao,Yiqiu Li,Hanxing Liu,Jing Xu,Hua Hao,Minghe Cao,Zhiyong Yu 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.3
The compositions of (1-x) SrTiO3-x SiO2 were prepared by a solid-state reaction. The crystalline structure, microstructure and energy storage performance were studied for the purpose of a potential application in high energy density capacitors. Fine grains with an average size of about 400 nm were obtained by adding SiO2 to SrTiO3 ceramics, which leads to a great enhancement in the breakdown performance of the samples. For SiO2-added samples, the notable increase in breakdown strength makes an obvious increase in energy storage density. With 15 vol.% addition, the sample exhibited an average breakdown strength of 36.1 kV/mm, and an energy storage density of 1.155 J/cm3.
Adaptive Complex Interpolator for Channel Estimation in Pilot-Aided OFDM System
Guanghui Liu,Liaoyuan Zeng,Hongliang Li,Linfeng Xu,ZhengningWang 한국통신학회 2013 Journal of communications and networks Vol.15 No.5
In an orthogonal frequency division multiplexing system,conventional interpolation techniques cannot correctly balanceperformance and overhead when estimating dynamic longdelaychannels in single frequency networks (SFNs). In this study,classical filter analysis and design methods are employed to derivea complex interpolator for maximizing the resistible echo delay in achannel estimator on the basis of the correlation between frequencydomain interpolating and time domain windowing. The coefficientcomputation of the complex interpolator requires a key parameter,i.e., channel length, which is obtained in the frequency domain witha tentative estimation scheme having low implementation complexity. The proposed complex adaptive interpolator is verified in asimulated digital video broadcasting for terrestrial/handheld receiver. The simulation results indicate that the designed channelestimator can not only handle SFN echoes with more than 200 µsdelay but also achieve a bit-error rate performance close to the optimumminimum mean square error method, which significantlyoutperforms conventional channel estimation methods, while preservinga low implementation cost in a short-delay channel.
Robust CFO Acquisition in PN-Padded OFDM Systems
Guanghui Liu,Liaoyuan Zeng,Hongliang Li,Linfeng Xu,ZhengningWang 한국전자통신연구원 2013 ETRI Journal Vol.35 No.4
As an alternative to the traditional pilot-aided orthogonal frequency division multiplexing (OFDM), the time-domain pseudonoise (PN)-padded OFDM provides a higher spectral efficiency. However, the carrier frequency offset (CFO) attenuates peaks of the conventional PN correlation output, which limits the CFO estimation range of the OFDM synchronizer. An improved correlation is proposed in this letter to remove the CFO-induced amplitude attenuation of correlation peaks. For a synchronizer adopting the designed correlator, a larger range of CFO acquisition is obtained through using wider correlation windows with a smaller interval between them. The proposed method of CFO acquisition is verified in a digital terrestrial multimedia broadcast receiver, in which the synchronizer is able to acquire CFOs up to ±320 kHz in the DVB-T F1 channel. Furthermore, the acquisition range can be expanded in more favorable channels.
Finite Frequency Vibration Suppression for Space Flexible Structures in Tip Position Control
Shidong Xu,Guanghui Sun,Zhan Li 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.3
This paper presents a novel control strategy for the tip position and vibration control of a class of space flexible structures. The proposed control algorithm consists of finite frequency H∞ vibration control technique and fractional-order PDv control technique. More specially, a new finite frequency H∞ controller working in the inner feedback loop is proposed to suppress vibration modes and external disturbances, and a new fractional-order PDv controller is developed in the outer feedback loop to guarantee the desired position tracking performance. Compared with conventional methods, the proposed one could achieve better control results. Finally, an illustrative example is presented to demonstrate the robustness and effectiveness of the proposed composite control strategy
Adaptive Complex Interpolator for Channel Estimation in Pilot-Aided OFDM System
Liu, Guanghui,Zeng, Liaoyuan,Li, Hongliang,Xu, Linfeng,Wang, Zhengning The Korea Institute of Information and Commucation 2013 Journal of communications and networks Vol.15 No.5
In an orthogonal frequency division multiplexing system, conventional interpolation techniques cannot correctly balance performance and overhead when estimating dynamic long-delay channels in single frequency networks (SFNs). In this study, classical filter analysis and design methods are employed to derive a complex interpolator for maximizing the resistible echo delay in a channel estimator on the basis of the correlation between frequency domain interpolating and time domain windowing. The coefficient computation of the complex interpolator requires a key parameter, i.e., channel length, which is obtained in the frequency domain with a tentative estimation scheme having low implementation complexity. The proposed complex adaptive interpolator is verified in a simulated digital video broadcasting for terrestrial/handheld receiver. The simulation results indicate that the designed channel estimator can not only handle SFN echoes with more than $200{\mu}s$ delay but also achieve a bit-error rate performance close to the optimum minimum mean square error method, which significantly outperforms conventional channel estimation methods, while preserving a low implementation cost in a short-delay channel.
A Stage-Structured Predator-Prey System with Time Delay and Beddington-DeAngelis Functional Response
Wang, Lingshu,Xu, Rui,Feng, Guanghui Department of Mathematics 2009 Kyungpook mathematical journal Vol.49 No.4
A stage-structured predator-prey system with time delay and Beddington-DeAngelis functional response is considered. By analyzing the corresponding characteristic equation, the local stability of a positive equilibrium is investigated. The existence of Hopf bifurcations is established. Formulae are derived to determine the direction of bifurcations and the stability of bifurcating periodic solutions by using the normal form theory and center manifold theorem. Numerical simulations are carried out to illustrate the theoretical results.