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| 1 | Removal of polycyclic aromatic hydrocarbons from aqueous solution by raw and modified plant residue materials as biosorbents显示文摘Removal of polycyclic aromatic hydrocarbons(PAHs), e.g., naphthalene, acenaphthene, phenanthrene and pyrene, from aqueous solution by raw and modified plant residues was investigated to develop low cost biosorbents for organic pollutant abatement. Bamboo wood, pine wood, pine needles and pine bark were selected as plant residues, and acid hydrolysis was used as an easily modification method. The raw and modified biosorbents were characterized by elemental analysis, Fourier transform infrared spectroscopy and scanning electron microscopy. The sorption isotherms of PAHs to raw biosorbents were apparently linear, and were dominated by a partitioning process. In comparison, the isotherms of the hydrolyzed biosorbents displayed nonlinearity, which was controlled by partitioning and the specific interaction mechanism. The sorption kinetic curves of PAHs to the raw and modified plant residues fit well with the pseudo second-order kinetics model. The sorption rates were faster for the raw biosorbents than the corresponding hydrolyzed biosorbents, which was attributed to the latter having more condensed domains(i.e., exposed aromatic core). By the consumption of the amorphous cellulose component under acid hydrolysis, the sorption capability of the hydrolyzed biosorbents was notably enhanced, i.e., 6–18 fold for phenanthrene, 6–8 fold for naphthalene and pyrene and 5–8 fold for acenaphthene. The sorption coefficients(Kd) were negatively correlated with the polarity index [(O+N)/C], and positively correlated with the aromaticity of the biosorbents. For a given biosorbent, a positive linear correlation between logKoc and logKow for different PAHs was observed. Interestingly, the linear plots of logKoc–logKow were parallel for different biosorbents. These observations suggest that the raw and modified plant residues have great potential as biosorbents to remove PAHs from wastewater. | Zemin Xi Baoliang Chen | 2014 | Journal of Environmental Sciences2014，26，4： | 10 |
| 2 | Novel estimators of equivalent number of looks in polarimetric SAR imagery based on sub-matrices显示文摘The equivalent number of looks(ENL) is an important parameter in the multilook statistical model of polarimetric synthetic aperture radar(Pol-SAR). Recently, the maximum likelihood(ML) method was proposed and gave a good performance in the Gaussian model case by using the full covariance matrix instead of the intensity of Pol-SAR data, but it generated underestimates in the product model case. In this paper several novel ENL estimators are presented via certain cumulants of the log-determinant of the sub-matrices of the multilook polarimetric covariance matrix. The texture effect to the ENL estimates is eliminated, and the analytic estimators are derived. The estimators use the full covariance matrix and sub-matrices information, rather than the intensities of polarization channels. All the novel estimators are suitable for any texture model and thus provide more accurate results than many existing ones. Experiments using simulated data and real data are presented to evaluate the performance of different estimators. The results show that the second log-determinant moment(SLDM3)-based method is the best one among the novel estimators. At the same time this estimator has much less computational complexity. In addition, a novel distribution classification method is proposed by coloring the image via second- and third-order log-cumulants of the covariance matrix(MLC), which is helpful to assess the estimation result. | Tao LIU Haogui CUI Zemin XI Jun GAO | 2016 | Science China(Information Sciences)2016，59，6： | 7 |
| 3 | Modeling multilook polarimetric SAR images with heavy-tailed rayleigh distribution and novel estimation based on matrix log-cumulants显示文摘With the improvements in modern radar resolution,the Gaussian-fluctuation model based on the central limit theorem does not accurately describe the scattering echo from targets.In contrast,the heavytailed Rayleigh distribution,based on the generalized central limit theorem,performs well in modeling the synthetic aperture radar(SAR) images,whereas its application to multi-look image processing is difficult.We describe successful modeling of multilook polarimetric SAR images with the heavy-tailed Rayleigh distribution and present novel parameter estimators based on matrix log-cumulants for the heavy-tailed Rayleigh distribution including the equivalent number of looks(ENL).First,a compound variable of heavy-tailed Rayleigh distribution is divided into a product of a positive alpha-stable variable and a complex Gaussian variable.The parameter estimations of the characteristic exponent and scale parameter based on log-cumulants in a single polarization channel are then derived.Second,the matrix log-cumulants(MLCs) for full polarization in multilook images are obtained,which can be applied to estimate model parameters.Therefore,a novel ENL estimator based on MLC is presented that describes the model more precisely.Extended to all other multivariable product models,this estimator performs better than existing methods.Finally,calculations on both simulated and real data are performed that give good fits with theoretical results.Multilook processing in one image with a fixed pixel number can improve parameter estimations over single-look processing.Our heavy-tailed Rayleigh model with its parameter estimation provides a new method to analyze the multilook polarimetric SAR images for target detection and classification. | LIU Tao CUI HaoGui MAO Tao XI ZeMin GAO Jun | 2013 | Science China(Information Sciences)2013，56，6： | 4 |
| 4 | Cued search algorithm with uncertain detection performance for phased array radars显示文摘A cued search algorithm with uncertain detection performance is proposed for phased array radars.Firstly,a target search model based on the information gain criterion is presented with known detection performance,and the statistical characteristic of the detection probability is calculated by using the fluctuant model of the target radar cross section (RCS).Secondly,when the detection probability is completely unknown,its probability density function is modeled with a beta distribution,and its posterior probability distribution with the radar observation is derived based on the Bayesian theory.Finally simulation results show that the cued search algorithm with a known RCS fluctuant model can achieve the best performance,and the algorithm with the detection probability modeled as a beta distribution is better than that with a random selected detection probability because the model parameters can be updated by the radar observation to approach to the real value of the detection probability. | Jianbin Lu Hui Xiao Zemin Xi Mingmin Zhang | 2013 | Journal of Systems Engineering and Electronics2013，24，6： | 2 |
| 5 | Texture-invariant Estimation of Equivalent Number of Looks Based on Trace Moments in Polarimetric Radar Imagery显示文摘 | Liu Tao Cui Haogui Xi Zemin | 2014 | IEEE Geoscience and Remote Sensing Letters2014，11，6： | 1 |
| 6 | Multifunction Phased Array Radar Resource Management: Real-Time Schedu- ling Algorithm 显示文摘 | Lu Jianbin Xiao Hui Xi Zemin Mingmin Zhang | 2011 | Journal of Computational Information Sys- tems2011，7，2： | 1 |
| 7 | Analysis and Design of Multi-aspect SAR System for Compressive Sensing-Based 3D Imaging显示文摘This paper focuses on the analysis and design of Multi-aspect SAR(MuSAR) system for Compressive sensing-based(CS-based) 3D imaging. For this purpose,the Point ambiguous function(PAF) is proposed to analyze the factors that dominate the Mutual coherence(MC) of MuSAR sensing matrix. The PAF contacts with the parameters and configuration of MuSAR system directly and is easy to manipulate. With PAF, the present study analyzes the factors that dominate the performance of CS-based MuSAR 3D imaging. First of all, the stochastic waveform is an excellent selection. Second, the angular-frequency-diversity can improve the robustness of3 D imaging. Finally, the finer sampling of received data could improve the robustness of MuSAR 3D imaging. Simulation experiments show the validity of conclusion. | ZHOU Hanfei SU Yi XI Zemin LU Jianbin | 2014 | Chinese Journal of Electronics2014，23，3： | 0 |
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