A surface edge element method is proposed and implemented in the study ofelectromagnetic scattering fields of general targets. The basis functions for surfaces of arbitraryshape are derived according to the geometrica...A surface edge element method is proposed and implemented in the study ofelectromagnetic scattering fields of general targets. The basis functions for surfaces of arbitraryshape are derived according to the geometrical properties of each triangular patch. The proposedbasis functions are 3-D linear functions and the tangential components of the vectors are continuousas the traditional edge element method. Combined field integral equations (CFIE) that include bothelectrical field and magnetic field integral equations are used to model the electromagneticscattering of general dielectric targets. Special treatment for singularity is presented to enhancethe quality of numerical solutions. The proposed method is used to compute the scattering fieldsfrom various targets. Numerical results obtained by the proposed method are validated by resultsfrom other numerical methods.展开更多
ZrO2/PMMA nanocomposite particles are synthesized through an in-situ free radical emulsion polymerization based on the silane coupling agent （Z-6030） modified ZrO2 nanoparticles, and the morphology, size and its dis...ZrO2/PMMA nanocomposite particles are synthesized through an in-situ free radical emulsion polymerization based on the silane coupling agent （Z-6030） modified ZrO2 nanoparticles, and the morphology, size and its distribution of nanocomposite particles are investigated. Scanning electron microscopy （SEM） images demonstrate that the methyl methacrylate （MMA） feeding rate has a significant effect on the particle size and morphology. When the MMA feeding rate decreases from 0.42 ml-min-1 to 0.08 ml. min-1, large particles （about 200-550.nm） will not form, and the size distribution become narrow （36-54 nm）. The average nanocomposite particles size increases from 34 nm to 55 nm, as the MMA/ZrO2 nanoparticles mass ratio increased from 4 ： 1 to 16 ： 1. Regular spherical ZrO2/PMMA nanocomposite particles are synthesized when the emulsifier OP-10 concentration is 2 mg.m1-1. The nanocomposite particles could be mixed with VAc-VeoVa10 polymer matrix just by magnetic stirring to prepare the ZrOE/PMMA/VAc-VeoVal0 hybrid coatings. SEM and atomic force microscopy （AFM） photos reveal that the distribution of the ZrO2/PMMA nanocomposite particles in the VAc-VeoVal0 polymer matrix is homogenous and stable. Here, the grafted-PMMA polymer on ZrO2 nanoparticles plays as a bridge which effectively connects the ZrO2 nanoparticles and the VAc-VeoVal0 polymer matrix with improved comparability. In consequence, the hybrid coating with good dispersion stability is obtained.展开更多
Using the mapping method based on q-deformed hyperbolic functions,the exact solutions of generalizedBreor-Kaup equations are obtained.Based on the solutions,two coherent structures,periodic-branch kink and non-propaga...Using the mapping method based on q-deformed hyperbolic functions,the exact solutions of generalizedBreor-Kaup equations are obtained.Based on the solutions,two coherent structures,periodic-branch kink and non-propagating kink,have been obtained.Moreover,one solitonal interaction form,two line solitons interaction on the kinkbackground,has been found.展开更多
Using mean field method proposed in Ref. [4], the 40 Gb/s multi ― channelWDM optical fiber transmission systems with different dispersion maps are simulated. By this method,the computation time can be greatly reduced...Using mean field method proposed in Ref. [4], the 40 Gb/s multi ― channelWDM optical fiber transmission systems with different dispersion maps are simulated. By this method,the computation time can be greatly reduced since following only the full time evolution of alimited number of channels while treating the other channels as continuous wave. But sincedispersion plays an important role in the process of FWM and XPM, different dispersion maps willaffect the application of the method. The dependence of the method on dispersion maps isinvestigated. The results not only confirm the mean field method, but also give useful approach forsystem design.展开更多
Magnesium matrix nanocomposite reinforced with carbon nanotubes(CNTs/AZ91D) was fabricated by mechanical stirring and high intensity ultrasonic dispersion processing.The microstructures and mechanical properties of th...Magnesium matrix nanocomposite reinforced with carbon nanotubes(CNTs/AZ91D) was fabricated by mechanical stirring and high intensity ultrasonic dispersion processing.The microstructures and mechanical properties of the nanocomposite were investigated.The results show that CNTs are well dispersed in the matrix and combined with the matrix very well.As compared with AZ91D magnesium alloy matrix,the tensile strength,yield strength and elongation of the 1.5%CNTs/AZ91D nanocomposite are improved by 22%,21%and 42%respectively in permanent mold casting.The strength and ductility of the nanocomposite are improved simultaneously.The tensile fracture analysis shows that the damage mechanism of nanocomposite is still brittle fracture.But the CNTs can prevent the local crack propagation to some extent.展开更多
The article investigated the influence of modification process parameters on dispersity of MWNTs DI （in deionized） water and PVA/MWNT composite＇s electrical conductivity. Experimental results obtained by SEM （scan...The article investigated the influence of modification process parameters on dispersity of MWNTs DI （in deionized） water and PVA/MWNT composite＇s electrical conductivity. Experimental results obtained by SEM （scanning electron microscope）, TEM （transmission electron microscope）, transform Fourier infrared spectroscopy, pH meter confirmed the most effective conditions in modifying the MWNT surface at the 1：3 mixture of nitric and sulfuric acid at 60 ℃. The extinction coefficient value of functionalized MWNTs at 500 nm wavelength was determined to be 41.24 cm^2·mg^-1, while their dispersibility in DI water was about 12.85 mg/mL and stable in more than 3 weeks via UV-vis spectroscopy. The other important result is the decrease of volume resistivity from 7.98 × 10^6 MΩ·m ofPVA （polyvinyl alcohol） to 4.15 × 10^4 MΩ·m of PVA/1 wt% modified MWNT thin film.展开更多
A robust interference canceller for Multi-Carrier Code Division Multiple Access(MC-CDMA) using Orthogonal Frequency Division Multiplexing (OFDM) in Rayleigh fading isproposed. This interference canceller is robust in ...A robust interference canceller for Multi-Carrier Code Division Multiple Access(MC-CDMA) using Orthogonal Frequency Division Multiplexing (OFDM) in Rayleigh fading isproposed. This interference canceller is robust in the sense that it cancels Inter-Carriers Inter-ference (ICI) and is suitable for use in dispersive channels. To come up the effects of the signaldispersion, Doppler shifts and delay spreads on the performance of MC-CDMA systems over mo-bile fading channels, this interference canceller exploits the merit of the orthogonal signaling andpilot signals to evaluate the channel parameters. This interface canceller is well suited to work initerative turbo interference cancellation.展开更多
This paper investigates the distribution of intercarrier interference （ICI） in multiple-input multiple-output orthogonal frequency division multiplexing （MIMO-OFDM） systems based on the geometrical one-ring model....This paper investigates the distribution of intercarrier interference （ICI） in multiple-input multiple-output orthogonal frequency division multiplexing （MIMO-OFDM） systems based on the geometrical one-ring model. Using the spatial and temporal correlation of a geometrical one-ring model, a close-formed expression of intercarrier interference due to the Doppler effect caused by the movement of receiver is derived under the isotropic scattering conditions and non-isotropic scattering conditions. The analytical results are verified by Monte Carlo simulations. We use the generated channels to investigate MIMO-OFDM intercarrier interference under various channel parameters. It can be shown that more than 95% oflCI power comes from five neighboring subcarriers.展开更多
Two Gaussian air quality dispersion models, the industrial source complex short-term model (ISCST3) with and without modification have been used to simulate the pollutant concentration distribution in urban areas base...Two Gaussian air quality dispersion models, the industrial source complex short-term model (ISCST3) with and without modification have been used to simulate the pollutant concentration distribution in urban areas based on the meteorological data and the emissions distribution of sulfur dioxide. The verified data show that the modified model is more accurate in the urban area of Shijiazhuang. Using the modified model predictions, the control strategies of sulfur dioxide in the urban area have been studied, and the result show that the second long-term (to 2010) strategy can mitigate air pollution significantly and maintain pollution levels within permissible limits.展开更多
Previous study has shown that 10-hydroxycamptothecin（HCPT） has well-established pharmacological effects in vitro.However,its in vivo bioavailability is very poor due to various problems,which severely restricts its ...Previous study has shown that 10-hydroxycamptothecin（HCPT） has well-established pharmacological effects in vitro.However,its in vivo bioavailability is very poor due to various problems,which severely restricts its clinical applications.In the present study,phospholipid complex（PC） technology was employed to improve the solubility and bioavailability of HCPT.XRD data confirmed the formation of HCPT-PC.However,our previously prepared HCPT-PC is too sticky,which may result in the slow dissolution rate and negative effects on its absorption.Therefore,we prepared HCPT-PC-solid dispersion（HCPT-PC-SD）and lipid-based formulations of HCPT-PC through simple preparation process.The results showed that the dissolution rate of HCPT-PC was effectively improved by solid dispersion technology,which reached 91.73%in 45 min.Pharmacokinetic study revealed that the AUC_（0-t） of HCPT-PC-SD and HCPT-PC lipid-based formulations was effectively further increased compared with HCPT-PC.Moreover,we found that the combination of SD technology and lipid-base formulations could be a promising drug-delivery system to improve the oral bioavailability of HCPT-PC.In addition,we showed that the bioavailability of HCPT-PC lipid-base formulations was even greater than that of HCPT-PC-SD.In particular,lipid-base formulations could be prepared just by a simple method,suggesting its feasibility of industrialization.展开更多
Quercetin(QUE)has many beneficial biological activities and pharmacological actions in vitro.However,its oral bioavailability in vivo was very poor due to poor solubility,and severely restricted its clinical applicati...Quercetin(QUE)has many beneficial biological activities and pharmacological actions in vitro.However,its oral bioavailability in vivo was very poor due to poor solubility,and severely restricted its clinical applications.In this study,we prepared quercetin solid dispersion(QUE-SD)and quercetin phospholipids complex solid dispersion(QUE-PC-SD)by a solvent evaporation method to improve the absorption of QUE in vivo.The results of XRD of QUE-SD and QUE-PC-SD showed that QUE was dispersed homogeneously in an amorphous or molecular state in QUE-SD and QUE-PC-SD,which could contribute to improve the solubility and dissolution of QUE.The solubility of QUE-SD and QUE-PC-SD was enhanced from(4.03±0.02)μg/mL to(26.91=1=0.06)μg/mL and(30.65±0.06)μg/mL,respectively.The solubility of QUE-PC-SD was higher than that of QUE-SD.In vitro dissolution study,it was showed that the maximum dissolution of QUE(9.57%)from the QUE-SD and QUE-PC-SD was enhanced to 93.81%and 94.16%,respectively.The results of pharmacokinetic experiment indicated that the QUE-SD and QUE-PC-SD exhibited considerable enhancement in the oral bioavailability.The relative bioavailability of QUE-SD and QUE-PC-SD compared with QUE were 149.49%and 198.32%,respectively.In addition,the relative bioavailability of QUE-PC-SD was also higher than that of QUE-SD.Therefore,in regard to drugs with poor solubility and low permeation,an active constituent-PC-SD system could result to a better absorption and higher bioavailability.展开更多
In the present paper, the effective propagation constants of elastic SH waves in composites with randomly distributed parallel cylindrical nanofibers are studied. The surface stress effects are considered based on the...In the present paper, the effective propagation constants of elastic SH waves in composites with randomly distributed parallel cylindrical nanofibers are studied. The surface stress effects are considered based on the surface elasticity theory and non-classical interfacial conditions between the nanofiber and the host are derived. The scattering waves from individual nanofibers embedded in an infinite elastic host are obtained by the plane wave expansion method. The scattering waves from all fibers are summed up to obtain the multiple scattering waves. The interactions among random dispersive nanofibers are taken into account by the effective field approximation. The effective propagation constants are obtained by the configurational average of the multiple scattering waves. The effective speed and attenuation of the averaged wave and the associated dynamical effective shear modulus of composites are numerically calculated. Based on the numerical results, the size effects of the nanofibers on the effective propagation constants and the effective modulus are discussed.展开更多
A discrete nonlinear model of real estate is derived,with which the evolutionary trendamong government,consumers and real estate developers is described.The stability,bifurcation,andchaotic behavior of the system are ...A discrete nonlinear model of real estate is derived,with which the evolutionary trendamong government,consumers and real estate developers is described.The stability,bifurcation,andchaotic behavior of the system are also analyzed by using nonlinear dynamic method.Results show thatchaos can be obtained via quasi-periodic transition and double-periodic bifurcation.The influence ofdynamic evolutionary trend among stakeholder on system stability is also studied and some interestingconclusions are derived.This research can effectively explain the complex behavior of housing prices.展开更多
We experimentally assess the bit error rate(BER) performance of an intensity modulation/direct detection(IM/DD) optical orthogonal frequency division multiplexing(OFDM) system based on discrete Hartley transform(DHT) ...We experimentally assess the bit error rate(BER) performance of an intensity modulation/direct detection(IM/DD) optical orthogonal frequency division multiplexing(OFDM) system based on discrete Hartley transform(DHT) precoding in single-mode fiber(SMF) link for 2.5 Gbit/s quadrature phase shift keying(QPSK) OFDM symbol rate.The experimental results show that for the optical OFDM system based on DHT-precoding,the receiver sensitivity at the BER of 10-4 after 100 km SMF transmission is about 1.5 dBm better than that of the original QPSK OFDM signal,and the DHT-precoded OFDM QPSK signal can achieve approximately 1.3 dB of peak-to-average power ratio(PAPR) reduction.展开更多
文摘A surface edge element method is proposed and implemented in the study ofelectromagnetic scattering fields of general targets. The basis functions for surfaces of arbitraryshape are derived according to the geometrical properties of each triangular patch. The proposedbasis functions are 3-D linear functions and the tangential components of the vectors are continuousas the traditional edge element method. Combined field integral equations (CFIE) that include bothelectrical field and magnetic field integral equations are used to model the electromagneticscattering of general dielectric targets. Special treatment for singularity is presented to enhancethe quality of numerical solutions. The proposed method is used to compute the scattering fieldsfrom various targets. Numerical results obtained by the proposed method are validated by resultsfrom other numerical methods.
基金Supported by Production, Teaching & Research Combination Project for Universities in Guangdong Province(cgzhzd0904),Department of Education of Guangdong Province, China
文摘ZrO2/PMMA nanocomposite particles are synthesized through an in-situ free radical emulsion polymerization based on the silane coupling agent （Z-6030） modified ZrO2 nanoparticles, and the morphology, size and its distribution of nanocomposite particles are investigated. Scanning electron microscopy （SEM） images demonstrate that the methyl methacrylate （MMA） feeding rate has a significant effect on the particle size and morphology. When the MMA feeding rate decreases from 0.42 ml-min-1 to 0.08 ml. min-1, large particles （about 200-550.nm） will not form, and the size distribution become narrow （36-54 nm）. The average nanocomposite particles size increases from 34 nm to 55 nm, as the MMA/ZrO2 nanoparticles mass ratio increased from 4 ： 1 to 16 ： 1. Regular spherical ZrO2/PMMA nanocomposite particles are synthesized when the emulsifier OP-10 concentration is 2 mg.m1-1. The nanocomposite particles could be mixed with VAc-VeoVa10 polymer matrix just by magnetic stirring to prepare the ZrOE/PMMA/VAc-VeoVal0 hybrid coatings. SEM and atomic force microscopy （AFM） photos reveal that the distribution of the ZrO2/PMMA nanocomposite particles in the VAc-VeoVal0 polymer matrix is homogenous and stable. Here, the grafted-PMMA polymer on ZrO2 nanoparticles plays as a bridge which effectively connects the ZrO2 nanoparticles and the VAc-VeoVal0 polymer matrix with improved comparability. In consequence, the hybrid coating with good dispersion stability is obtained.
基金National Natural Science Foundation of China under Grant Nos.10535010 and 10775123the Research Fund of Ministry of Education under Grant No.20070284016
文摘Using the mapping method based on q-deformed hyperbolic functions,the exact solutions of generalizedBreor-Kaup equations are obtained.Based on the solutions,two coherent structures,periodic-branch kink and non-propagating kink,have been obtained.Moreover,one solitonal interaction form,two line solitons interaction on the kinkbackground,has been found.
文摘Using mean field method proposed in Ref. [4], the 40 Gb/s multi ― channelWDM optical fiber transmission systems with different dispersion maps are simulated. By this method,the computation time can be greatly reduced since following only the full time evolution of alimited number of channels while treating the other channels as continuous wave. But sincedispersion plays an important role in the process of FWM and XPM, different dispersion maps willaffect the application of the method. The dependence of the method on dispersion maps isinvestigated. The results not only confirm the mean field method, but also give useful approach forsystem design.
文摘Magnesium matrix nanocomposite reinforced with carbon nanotubes(CNTs/AZ91D) was fabricated by mechanical stirring and high intensity ultrasonic dispersion processing.The microstructures and mechanical properties of the nanocomposite were investigated.The results show that CNTs are well dispersed in the matrix and combined with the matrix very well.As compared with AZ91D magnesium alloy matrix,the tensile strength,yield strength and elongation of the 1.5%CNTs/AZ91D nanocomposite are improved by 22%,21%and 42%respectively in permanent mold casting.The strength and ductility of the nanocomposite are improved simultaneously.The tensile fracture analysis shows that the damage mechanism of nanocomposite is still brittle fracture.But the CNTs can prevent the local crack propagation to some extent.
文摘The article investigated the influence of modification process parameters on dispersity of MWNTs DI （in deionized） water and PVA/MWNT composite＇s electrical conductivity. Experimental results obtained by SEM （scanning electron microscope）, TEM （transmission electron microscope）, transform Fourier infrared spectroscopy, pH meter confirmed the most effective conditions in modifying the MWNT surface at the 1：3 mixture of nitric and sulfuric acid at 60 ℃. The extinction coefficient value of functionalized MWNTs at 500 nm wavelength was determined to be 41.24 cm^2·mg^-1, while their dispersibility in DI water was about 12.85 mg/mL and stable in more than 3 weeks via UV-vis spectroscopy. The other important result is the decrease of volume resistivity from 7.98 × 10^6 MΩ·m ofPVA （polyvinyl alcohol） to 4.15 × 10^4 MΩ·m of PVA/1 wt% modified MWNT thin film.
基金the National Natural Science Foundation of China(No.60172048)
文摘A robust interference canceller for Multi-Carrier Code Division Multiple Access(MC-CDMA) using Orthogonal Frequency Division Multiplexing (OFDM) in Rayleigh fading isproposed. This interference canceller is robust in the sense that it cancels Inter-Carriers Inter-ference (ICI) and is suitable for use in dispersive channels. To come up the effects of the signaldispersion, Doppler shifts and delay spreads on the performance of MC-CDMA systems over mo-bile fading channels, this interference canceller exploits the merit of the orthogonal signaling andpilot signals to evaluate the channel parameters. This interface canceller is well suited to work initerative turbo interference cancellation.
文摘This paper investigates the distribution of intercarrier interference （ICI） in multiple-input multiple-output orthogonal frequency division multiplexing （MIMO-OFDM） systems based on the geometrical one-ring model. Using the spatial and temporal correlation of a geometrical one-ring model, a close-formed expression of intercarrier interference due to the Doppler effect caused by the movement of receiver is derived under the isotropic scattering conditions and non-isotropic scattering conditions. The analytical results are verified by Monte Carlo simulations. We use the generated channels to investigate MIMO-OFDM intercarrier interference under various channel parameters. It can be shown that more than 95% oflCI power comes from five neighboring subcarriers.
文摘Two Gaussian air quality dispersion models, the industrial source complex short-term model (ISCST3) with and without modification have been used to simulate the pollutant concentration distribution in urban areas based on the meteorological data and the emissions distribution of sulfur dioxide. The verified data show that the modified model is more accurate in the urban area of Shijiazhuang. Using the modified model predictions, the control strategies of sulfur dioxide in the urban area have been studied, and the result show that the second long-term (to 2010) strategy can mitigate air pollution significantly and maintain pollution levels within permissible limits.
基金Science and Technology Department of Henan province Fund Project(Grant No.144300510019)
文摘Previous study has shown that 10-hydroxycamptothecin（HCPT） has well-established pharmacological effects in vitro.However,its in vivo bioavailability is very poor due to various problems,which severely restricts its clinical applications.In the present study,phospholipid complex（PC） technology was employed to improve the solubility and bioavailability of HCPT.XRD data confirmed the formation of HCPT-PC.However,our previously prepared HCPT-PC is too sticky,which may result in the slow dissolution rate and negative effects on its absorption.Therefore,we prepared HCPT-PC-solid dispersion（HCPT-PC-SD）and lipid-based formulations of HCPT-PC through simple preparation process.The results showed that the dissolution rate of HCPT-PC was effectively improved by solid dispersion technology,which reached 91.73%in 45 min.Pharmacokinetic study revealed that the AUC_（0-t） of HCPT-PC-SD and HCPT-PC lipid-based formulations was effectively further increased compared with HCPT-PC.Moreover,we found that the combination of SD technology and lipid-base formulations could be a promising drug-delivery system to improve the oral bioavailability of HCPT-PC.In addition,we showed that the bioavailability of HCPT-PC lipid-base formulations was even greater than that of HCPT-PC-SD.In particular,lipid-base formulations could be prepared just by a simple method,suggesting its feasibility of industrialization.
基金National Science and Technology Major Projects “Major New Drugs Innovation and Development”(Grant No.2018ZX09201019-002-009)
文摘Quercetin(QUE)has many beneficial biological activities and pharmacological actions in vitro.However,its oral bioavailability in vivo was very poor due to poor solubility,and severely restricted its clinical applications.In this study,we prepared quercetin solid dispersion(QUE-SD)and quercetin phospholipids complex solid dispersion(QUE-PC-SD)by a solvent evaporation method to improve the absorption of QUE in vivo.The results of XRD of QUE-SD and QUE-PC-SD showed that QUE was dispersed homogeneously in an amorphous or molecular state in QUE-SD and QUE-PC-SD,which could contribute to improve the solubility and dissolution of QUE.The solubility of QUE-SD and QUE-PC-SD was enhanced from(4.03±0.02)μg/mL to(26.91=1=0.06)μg/mL and(30.65±0.06)μg/mL,respectively.The solubility of QUE-PC-SD was higher than that of QUE-SD.In vitro dissolution study,it was showed that the maximum dissolution of QUE(9.57%)from the QUE-SD and QUE-PC-SD was enhanced to 93.81%and 94.16%,respectively.The results of pharmacokinetic experiment indicated that the QUE-SD and QUE-PC-SD exhibited considerable enhancement in the oral bioavailability.The relative bioavailability of QUE-SD and QUE-PC-SD compared with QUE were 149.49%and 198.32%,respectively.In addition,the relative bioavailability of QUE-PC-SD was also higher than that of QUE-SD.Therefore,in regard to drugs with poor solubility and low permeation,an active constituent-PC-SD system could result to a better absorption and higher bioavailability.
基金supported by the National Natural Science Foundation of China (Grant No. 10972029)
文摘In the present paper, the effective propagation constants of elastic SH waves in composites with randomly distributed parallel cylindrical nanofibers are studied. The surface stress effects are considered based on the surface elasticity theory and non-classical interfacial conditions between the nanofiber and the host are derived. The scattering waves from individual nanofibers embedded in an infinite elastic host are obtained by the plane wave expansion method. The scattering waves from all fibers are summed up to obtain the multiple scattering waves. The interactions among random dispersive nanofibers are taken into account by the effective field approximation. The effective propagation constants are obtained by the configurational average of the multiple scattering waves. The effective speed and attenuation of the averaged wave and the associated dynamical effective shear modulus of composites are numerically calculated. Based on the numerical results, the size effects of the nanofibers on the effective propagation constants and the effective modulus are discussed.
基金supported by the National Natural Science Foundation of China under Grant Nos. 60641006,70872029.
文摘A discrete nonlinear model of real estate is derived,with which the evolutionary trendamong government,consumers and real estate developers is described.The stability,bifurcation,andchaotic behavior of the system are also analyzed by using nonlinear dynamic method.Results show thatchaos can be obtained via quasi-periodic transition and double-periodic bifurcation.The influence ofdynamic evolutionary trend among stakeholder on system stability is also studied and some interestingconclusions are derived.This research can effectively explain the complex behavior of housing prices.
基金supported in part by the National Natural Science Foundation of China(No.61302112)the Open Fund of the State Key Laboratory of Millimeter Waves(Southeast University,Ministry of Education,China)(No.K201214)+1 种基金the Zhejiang Provincial Natural Science Foundation of China(No.LY13F050005)the Key Industrial Project of Special Major Science and Technology of Zhejiang Province(No.2012C11016-2)
文摘We experimentally assess the bit error rate(BER) performance of an intensity modulation/direct detection(IM/DD) optical orthogonal frequency division multiplexing(OFDM) system based on discrete Hartley transform(DHT) precoding in single-mode fiber(SMF) link for 2.5 Gbit/s quadrature phase shift keying(QPSK) OFDM symbol rate.The experimental results show that for the optical OFDM system based on DHT-precoding,the receiver sensitivity at the BER of 10-4 after 100 km SMF transmission is about 1.5 dBm better than that of the original QPSK OFDM signal,and the DHT-precoded OFDM QPSK signal can achieve approximately 1.3 dB of peak-to-average power ratio(PAPR) reduction.
