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Lu B.,ZheJiang Surveying Institute of Estuary and Coast | Jin J.-P.,ZheJiang Surveying Institute of Estuary and Coast | Duan W.-Y.,ZheJiang Surveying Institute of Estuary and Coast | Chen L.-J.,ZheJiang Surveying Institute of Estuary and Coast | Guan H.-Y.,ZheJiang Surveying Institute of Estuary and Coast
Advanced Materials Research | Year: 2012

GPS multipath disturbance is a bottleneck problem that limits accuracy of GPS positioning. The function of single epoch kinematic positioning of GAMIT TRACK is used to study GPS signal multipath effects. A filtering method for separating signal and noise based on the wavelet analysis is established. The decomposition level for wavelet filter is confirmed according to the high correlation of the multipath effects between adjacent sidereal days by using the maximum correlation coefficient method. The accurate multipath corrections in GPS coordinate series are acquired with the proposed method making use of TRACK and the repeating property of multipath effects is used to weaken multipath effects in subsequent days, and therefore improve the precision of the GPS positioning. © (2012) Trans Tech Publications, Switzerland.


Xu H.-Y.,Zhejiang Shuren University | Wang W.,Zhejiang Surveying Institute of Estuary and Coast | Zou J.-W.,Zhejiang Shuren University | Zou J.-W.,Zhejiang University | Xu X.-L.,Zhejiang Shuren University
Journal of Theoretical and Computational Chemistry | Year: 2014

The pnicogen bonding interactions of PCl3 and π-electron systems (acetylene, ethylene, benzene) were calculated by using MP2/aug-cc-pVDZ method and the effect of hydrogen bond on pnicogen bond systems were investigated. It has been indicated that the hydrogen bonding and the pnicogen bonding interactions have influence on each other and the positively cooperative effect has been detected. The interaction energies of pnicogen bonded supramolecular system were also calculated by using DFT method (M06-2X) and some simple comparisons with those by using MP2 method were made. It has been disclosed from natural bond orbitals (NBO) analysis that more the amount of charge transfer of pnicogen bonding interaction, the greater the stability of the corresponding complex. Through AIM topological analysis, it has been revealed that the electron density of pnicogen bond BCP point is positively correlated with the stability of trimeric complex. Electron localization function (ELF) was also adopted to analyze the nature of pnicogen bonding interactions. Furthermore, density difference function (DDF) method was adopted to analyze the variation of electron density of pnicogen bond system because of hydrogen bond. © 2014 World Scientific Publishing Company.


Jiang X.,Zhejiang Surveying Institute of Estuary and Coast | Ren S.,Zhejiang Surveying Institute of Estuary and Coast | Shi Y.,Zhejiang Surveying Institute of Estuary and Coast
Proceedings - 2012 20th International Conference on Geoinformatics, Geoinformatics 2012 | Year: 2012

Aiming at the deficiencies in the field of Marine Sub-bottom Acoustic Exploration (MSAE), such as inefficiency in data management and limitation in data representation, full analyses are made on the technology and the exploring data of MSAE. A theme-based data integration model is proposed for MSAE data integration based on the themes of geomorphology, topography, and stratigraphy. The efficiencies of MSAE data management and use are consequently improved. Then a feature-based and application-oriented data fusion model is proposed for the full use and visual representation of the MSAE data. Evaluation of the two proposed models and their results are then made. With the successful application of the marine pipe route inspection (MPRI) in Hangzhou Bay, a GIS prototype system is constructed. All these studies show that the proposed models can improve the efficiencies of data management and use, meet the data needs of higher level applications, and implement the consistent visual data representation, in the field of MSAE. It can provide some references to the related applications in the field. © 2012 IEEE.


Wang W.,Zhejiang Surveying Institute of Estuary and Coast | Xu H.-Y.,Zhejiang Shuren University | Zhou L.-Y.,Hangzhou Environmental Monitoring Station | Tang D.-Y.,Zhejiang Surveying Institute of Estuary and Coast
Jiegou Huaxue | Year: 2015

Based on the relationship between the quantitative structure and property (QSPR) of organic compounds, the surface electrostatic potential parameters of 29 polychlorinated diphenyl sulfides (PCDPSs) with experimental values were calculated and extracted, and Multiple Linear Regression (MLR) was used to model the linear relationship between the physicochemical properties (octanol/water partition coefficient, high performance liquid chromatography capacity factor) and molecular structure parameters of PCDPSs. The result shows that the main factors that affect the n-octanol/water partition coefficient and high performance liquid chromatography capacity factor are respectively the number of chlorin atoms substituted on the benzene ring (NCl) and the lowest unoccupied molecular orbital energy (ELUMO). Secondly, there are also molecular surface electrostatic potentials. This indicates that the molecular surface electrostatic potentials can effectively express the quantitative relationship between the physicochemical properties of PCDPSs and their molecule descriptions. The QSPR models established have strong stability and predictive ability. This also has proved the applicability of molecular surface electrostatic potential parameters in QSPR of PCDPSs.


Xu H.,Zhejiang Shuren University | Zhu J.,Zhejiang Shuren University | Lei C.,Zhejiang Shuren University | Xu X.,Zhejiang Shuren University | And 3 more authors.
Bulletin of Environmental Contamination and Toxicology | Year: 2016

The distribution patterns of perfluorinated compounds (PFCs) in the surface waters of Xixi wetland, China, were investigated for the first time. Among the eight PFCs investigated, only perfluorooctanoic acid (PFOA), perfluoroheptanoic acid (PFHpA) and perfluorononanoic acid (PFNA) were detected. PFOA was the most prominent PFC, and detected in all of the samples with higher PFOA concentrations (maximum: 197.8 ng L−1), followed by PFHpA (maximum: 3.97 ng L−1). Geographical differences in PFC levels were not observed among various sampling locations except for the YanShan River location, but seasonal changes have been observed for PFOA. The study suggested that the water diversion project from the Qiantang River to the Xixi Wetland may have significantly contributed to the increase of PFOA level, and that domestic sewage and farmland irrigation runoff are constant pollution sources to the Xixi Wetland. © 2016 Springer Science+Business Media New York


Xu H.-Y.,Zhejiang Shuren University | Wang W.,Zhejiang Surveying Institute of Estuary and Coast | Xu X.-L.,Zhejiang Shuren University
International Journal of Environment and Pollution | Year: 2015

Recently, there has been increasing concern about perfluorinated compounds, especially perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). To characterise the seasonal change of PFOS and PFOA in the Qiantang River waters of China, 48 water samples from March to September in 2013 were collected and analysed in this study. The concentrations of PFOS and PFOA were n.d-1.186 ng/L and from 5.35-137.5 ng/L, respectively. PFOS has been observed at a low concentration in these samples, while PFOA was detected in 100% of the samples with higher PFOA concentrations. PFOA concentrations were far higher than those of PFOS in all the samples, which were influenced by the inflows of the chemicals from a lot of the textile dyeing industry along the south bank of the river. Although the PFOS and PFOA concentrations in Qiantang River water samples did not exceed this provisional health advisory level (limit) established by the United States Environmental Protection Agency for PFOS and PFOA in drinking waters of 200 ng L-1 and 400 ng L-1 respectively, continued exposure to even relatively low PFOS and PFOA concentrations in drinking water may increase the risk of health effects. Copyright © 2015 Inderscience Enterprises Ltd.


Xu Q.,Hohai University | Zheng J.,Zhejiang Surveying Institute of Estuary and Coast | Cheng Y.,Old Dominion University | Cheng Y.,Nanjing University of Information Science and Technology | And 3 more authors.
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2016

In this paper, marine oil spills were detected from Synthetic Aperture Radar (SAR) images using two separate Artificial Neural Networks (ANNs) in sequence. The first ANN, i.e., the Back-Propagation Neural Network (BPNN), was employed to segment a SAR image for identifying the dark spots, which are caused by the oil spills or 'lookalikes'. Based on the extracted statistical features, the second BPNN was driven to distinguish oil spills from look-alikes. The overall accuracies of 84% were obtained for pixel segmentation and 73% for oil classification. In addition, sensitive experiments were carried out to investigate the influence of different features on the accuracy of oil classification. Results show that the wind speed and direction play a most important role in accurate identification of oil spills from SAR images. © Copyright 2016 by the International Society of Offshore and Polar Engineers (ISOPE).


Xie D.-F.,Zhejiang Institute of Hydraulics and Estuary | Pan C.-H.,Zhejiang Institute of Hydraulics and Estuary | Lu B.,Zhejiang Surveying Institute of Estuary and Coast | Ye X.-F.,Zhejiang Surveying Institute of Estuary and Coast
Shuidonglixue Yanjiu yu Jinzhan/Chinese Journal of Hydrodynamics Ser. A | Year: 2012

Based on the several field measurements of tidal bore on the Qiantang Estuary in recent years, the hydrodynamic characteristics of the tidal bore have been researched. The distributions of tidal levels, flood and ebb durations and current velocities along the river were influenced distinctly by the large sandbar of the estuary. During spring tide the vertical profiles of current velocities were parabolic at the bore arrival and this lasted for one hour, and then the vertical profiles turned to be logarithmic. During neap and middle tides, velocity vertical profiles were logarithmic at both flood and ebb tides. The vertical velocities were smaller by one order of magnitude than those of horizontal velocities, when the bore arrived, the vertical velocity increased obviously. The heights of the bore fronts have positive relationship with local tidal ranges. The Froude numbers at the bore arrival were calculated and the results showed that the Froude number could be used to justify the forms of the tidal bore. Furthermore, an analytic formula was built to analyze the gradient of the water surface of the bore front, by which the water surface changes during the tidal bore passing by were reproduced.


PubMed | Zhejiang Shuren University and Zhejiang Surveying Institute of Estuary and Coast
Type: Journal Article | Journal: Bulletin of environmental contamination and toxicology | Year: 2016

The distribution patterns of perfluorinated compounds (PFCs) in the surface waters of Xixi wetland, China, were investigated for the first time. Among the eight PFCs investigated, only perfluorooctanoic acid (PFOA), perfluoroheptanoic acid (PFHpA) and perfluorononanoic acid (PFNA) were detected. PFOA was the most prominent PFC, and detected in all of the samples with higher PFOA concentrations (maximum: 197.8ngL

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