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Biodegradation of polycyclic aromatic hydrocarbons in sediments from the Daliao River watershed, china

Journal of Environmental Sciences 2009年第7期21卷 865-871页

作者： QUAN Xiangchun, TANG Qian, HE Mengchang, YANG Zhifeng, LIN Chunye, GUO Wei State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Beijing Normal University, Beijing 100875, china. [a]State Key Joint Laboratory of Environmental Simulation and Pollution Control School of Environment Beijing Normal University Beijing 100875 China

The Daliao River, as an important water system in Northeast china, was reported to be heavily polluted by polycyclic aromatic hydrocarbons （PAHs）. Aerobic biodegradations of four selected PAHs （naphthalene, phenanthrene, fluorene and anthracene） alone or in their mixture in river sediments from the Daliao River water systems were studied in microcosm systems. Effects of additional carbon source, inorganic nitrogen and phosphorus, temperature variation on PAHs degradation were also investigated. results showed that the degradation of phenanthrene in water alone system was faster than that in water-sediment combined system. Degradation of phenanthrene in sediment was enhanced by adding yeast extract and ammonium, but retarded by adding sodium acetate and not significantly influenced by adding phosphate. Although PAHs could also be biodegraded in sediment under low temperature （5~C）, much lower degradation rate was observed. Sediments from the three main streams of the Daliao River water system （the Hun River, the Taizi River and the Daliao River） demonstrated different degradation capacities and patterns to four PAHs. Average removal rates （15 or 19 d） of naphthalene, phenanthrene, fluorene and anthracene by sediment were in the range of 0.062-0.087, 0.005-0.066, 0.008- 0.016 and 0-0.059 mg/（L.d）, respectively. As a result, naphthalene was most easily degraded compound, anthracene was the hardest one. In multiple PAHs systems, the interactions between PAHs influenced each PAH biodegradation.

关键词： biodegradation the Daliao River microcosm polycyclic aromatic hydrocarbon sediment

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Stepwise approach for view synthesis

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第8期8卷 1218-1226页

作者： CHAI Deng-feng PENG Qun-sheng State Key Lab of CAD and CG Zhejiang University Hangzhou 310027 China Institute of Spatial Information Technique Zhejiang University Hangzhou 310027 China

This paper presents some techniques for synthesizing novel view for a virtual viewpoint from two given views cap-tured at different viewpoints to achieve both high quality and high efficiency. The whole process consists of three passes. The first pass recovers depth map. We formulate it as pixel labelling and propose a bisection approach to solve it. It is accomplished in log2n(n is the number of depth levels) steps,each of which involves a single graph cut computation. The second pass detects occluded pixels and reasons about their depth. It fits a foreground depth curve and a background depth curve using depth of nearby fore-ground and background pixels,and then distinguishes foreground and background pixels by minimizing a global energy,which involves only one graph cut computation. The third pass finds for each pixel in the novel view the corresponding pixels in the input views and computes its color. The whole process involves only a small number of graph cut computations,therefore it is efficient. And,visual artifacts in the synthesized view can be removed successfully by correcting depth of the occluded pixels. Experimental results demonstrate that both high quality and high efficiency are achieved by the proposed techniques.

关键词： View synthesis Occlusion Graph cut

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Transformer real-time reliability model based on operating conditions

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第3期8卷 378-383页

作者： HE Jian CHENG Lin SUN Yuan-zhang State Key Laboratory of Power Systems Department of Electrical Engineering Tsinghua University Beijing 100084 China

Operational reliability evaluation theory reflects real-time reliability level of power system. The component failure rate varies with operating conditions. The impact of real-time operating conditions such as ambient temperature and transformer MVA (megavolt-ampere) loading on transformer insulation life is studied in this paper. The formula of transformer failure rate based on the winding hottest-spot temperature (HST) is given. Thus the real-time reliability model of transformer based on oper- ating conditions is presented. The work is illustrated using the 1979 IEEE reliability Test System. The changes of operating conditions are simulated by using hourly load curve and temperature curve, so the curves of real-time reliability indices are ob- tained by using operational reliability evaluation.

关键词： Operational reliability real-time reliability model Transformer Winding hottest-pot temperature (HST)

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Joint application of feature extraction based on EMD-AR strategy and multi-class classifier based on LS-SVM in EMG motion classification

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第8期8卷 1246-1255页

作者： YAN Zhi-guo WANG Zhi-zhong reN Xiao-mei Departmen of Biomedical Engineering Shanghai Jiao Tong University Shanghai 200030 China

This paper presents an effective and efficient combination of feature extraction and multi-class classifier for motion classification by analyzing the surface electromyografic(sEMG) signals. In contrast to the existing methods,considering the non-stationary and nonlinear characteristics of EMG signals,to get the more separable feature set,we introduce the empirical mode decomposition(EMD) to decompose the original EMG signals into several intrinsic mode functions(IMFs) and then compute the coefficients of autoregressive models of each IMF to form the feature set. Based on the least squares support vector machines(LS-SVMs) ,the multi-class classifier is designed and constructed to classify various motions. The results of contrastive experiments showed that the accuracy of motion recognition is improved with the described classification scheme. Furthermore,compared with other classifiers using different features,the excellent performance indicated the potential of the SVM techniques embedding the EMD-AR kernel in motion classification.

关键词： Electromyografic signal Empirical mode decomposition (EMD) Auto-regression model Wavelet packet transform Least squares support vector machines (LS-SVM) Neural network

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Multifractal analysis of surface EMG signals for assessing muscle fatigue during static contractions

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第6期8卷 910-915页

作者： WANG Gang reN Xiao-mei LI Lei WANG Zhi-zhong Department of Biomedical Engineering Shanghai Jiao Tong University Shanghai 200240 China

This study is aimed at assessing muscle fatigue during a static contraction using multifractal analysis and found that the surface electromyographic （SEMG） signals characterized multiffactality during a static contraction. By applying the method of direct determination ofthef（a） singularity spectrum, the area of the multifractal spectrum of the SEMG signals was computed. The results showed that the spectrum area significantly increased during muscle fatigue. Therefore the area could be used as an assessor of muscle fatigue. Compared with the median frequency （MDF）--the most popular indicator of muscle fatigue, the spectrum area presented here showed higher sensitivity during a static contraction. So the singularity spectrum area is considered to be a more effective indicator than the MDF for estimating muscle fatigue.

关键词： Muscle fatigue Surface electromyographic (SEMG) signals Multifractal Static contraction

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Effect of orbital errors on the geosynchronous circular synthetic aperture radar imaging and interferometric processing

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Journal of Zhejiang University-Science C(Computers and Electronics) 2011年第5期12卷 404-416页

作者： Lei-lei KOU Xiao-qing WANG Mao-sheng XIANG Jin-song CHONG Min-hui ZHU national Key Laboratory of Microwave Imaging Technology Institute of Electronics Beijing 100190 China Graduate University of Chinese Academy of Sciences Beijing 100190 China

The geosynchronous circular synthetic aperture radar (GEOCSAR) is an innovative SAR system,which can produce high resolution three-dimensional (3D) images and has the potential to provide 3D deformation *** an orbit altitude of approximately 36 000 km,the orbit motion and orbit disturbance effects of GEOCSAR behave differently from those of the conventional spaceborne *** this paper,we analyze the effects of orbit errors on GEOCSAR imaging and interferometric ***,we present the GEOCSAR imaging geometry and the orbit errors model based on perturbation ***,we give the GEOCSAR signal formulation based on imaging geometry,and analyze the effect of the orbit error on the output focused *** interferometric processing on the 3D reconstructed images,the relationship between satellite orbit errors and the interferometric phase is *** demonstrate the effects of orbit errors on the GEOCSAR images,interferograms,and the *** conclusions are that the required relative accuracy of orbit estimation should be at centimeter level for GEOCSAR imaging at L-band,and that millimeter-scale accuracy is needed for GEOCSAR interferometric processing.

关键词： Geosynchronous circular synthetic aperture radar (GEOCSAR) Orbit error Imaging Interferometric processing

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Numerical analysis on car-following traffic flow models with delay time

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第2期7卷 204-209页

作者：李莉施鹏飞 Institute of Image Processing and Pattern recognition Shanghai Jiao Tong University Shanghai 200030 China

Effects of the speed relaxation time on the optimal velocity car-following model (OVM) with delay time due to driver reaction time proposed by Bando et al.(1995) were studied by numerical methods. results showed that the OVM including the delay is not physically sensitive to the speed relaxation times. A modified car-following model is proposed to overcome the deficiency. Analyses of the linear stability of the modified model were conducted. It is shown that coexisting flows appear if the initial homogeneous headway of the traffic flow is between critical values. In addition, phase transitions occur on varying the initially homogeneous headway.

关键词： Car-following models Delay time relaxation time Phase transitions

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Competition of bloom-forming marine phytoplankton at low nutrient concentrations

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Journal of Environmental Sciences 2011年第4期23卷 656-663页

作者： Hanhua Hu Jun Zhang Weidong Chen State Key Laboratory of Freshwater Ecology and Biotechnology Institute of Hydrobiology Chinese Academy of Sciences Wuhan 430072 China. School of Life Sciences Xiamen University Xiamen 361005 China Department of Gene regulation and Drug Discovery Beckman Research Institute City of Hope National Medical Center Duarte CA 91010 USA

Competition of three bloom-forming marine phytoplankton （diatom Skeletonema costatum, and dinoflagellates Prorocentrum minimum and Alexandrium tamarense） was studied through a series of multispecies cultures with different nitrate （NaNO 3 ） and phosphate （NaH 2 PO 4 ） levels and excess silicate to interpret red tide algae succession. S. costatum outgrew the other two dinoflagellates in nitrate and phosphate replete cultures with 10 μmol/L Na 2 SiO 3 . Under nitrate limited （8.82 μmol/L NaNO 3 ） conditions, the growth of S. costatum was also dominant when phosphate concentrations were from 3.6 to 108 μmol/L. Cell density of the two dinoflagellates only increased slightly, to less than 400 and 600 cells/mL, respectively. Cell density of S. costatum decreased with time before day 12, and then increased to 4000 cells/mL （1.5 mg/L dry biomass） at NaNO 3 concentrations between 88.2 and 882 μmol/L with limited phosphate （0.36 μmol/L NaH 2 PO 4 ） levels. In addition, P. minimum grew well with a maximal cell density of 1690–2100 cells/mL （0.5–0.6 mg/L dry biomass）. Although S. costatum initially grew fast, its cell density decreased quickly with time later in the growth phase and the two dinoflagellates were dominant under the nitrate-limited and high nitrate conditions with limited phosphate. These results indicated that the diatom was a poor competitor compared to the two dinoflagellates under limited phosphate; however, it grew well under limited nitrate when growth of the dinoflagellates was near detection limits.

关键词： Alexandrium tamarense nitrate phosphate Prorocentrum minimum red tides Skeletonema costatum

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Detailed sedimentary facies of a sandstone reservoir in the eastern zone of the Sulige gas field, Ordos Basin

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Mining Science and Technology 2010年第6期20卷 891-897,903页

作者： LI Yijun ZHAO Yong YANG renchao FAN Aiping LI Fuping Sulige Gas Field research Center Changqing Oilfield Company Xi "an 710018 China College of Geological Science and Engineering Shandong University of Science and Technology Qingdao 266510 China

Given sustaining exploration, the eastern zone of the Sulige gas field may soon become a key area of exploitation. In order to explore its genesis, types and distribution of the reservoir sandstones in the eastern zone of this gas field, we focused in our study on the provenance and detailed sedimentary facies of sandstone of the He8 （the eighth part of the Shihezi formation, Permian system） and Shanxil （the first part of the Shanxi formation, Permian system） members, based on core observations, analyses in petrography, granularity and logging. The results show that： 1） the sandstone provenance of Shanxil and He8 in the eastern zone of the Sulige gas field is from the north of the Ordos Basin, characterized by dual directions from the north and northeast. 2） The He8 and Shanxil members were deposited in a fluvial-delta sedimentary system. The He8 was mainly deposited in braided rivers, in- cluding braided channels, channel bars, levee and floodplain sub-environments, whereas the Shanxil Member was deposited in braided rivers and deltas, including braided channels, channel bars, floodplains, tributaries and inter-tributary sub-environments. 3） Sedimentary facies bands migrated in drastic fashion towards the basin from the Shanxil to the He8 Member. Base levels of sedi- mentation generally present a trend of small increases in-amplitude, large decreasing amplitudes and slow and gradual Increases. 4） The continuity of the reservoir sandbodies along the source direction is better than that perpendicular to the direction. Compared with Shanxil, both dimensions and continuity of the sandbodies in He8 are better from which we conclude that it is the most fa- vorable part of the reservoir.

关键词： Ordos Basin Sulige gas field Permian sandstone reservoir detailed sedimentary facies

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MILD Combustion for Hydrogen and Syngas at Elevated Pressures

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Journal of Thermal Science 2014年第1期23卷 96-102页

作者： HUANG Mingming ZHANG Zhedian SHAO Weiwei XIONG Yan LEI Fulin XIAO Yunhan Key Laboratory of Advanced Energy and Power Institute of Engineering ThermophysicsChinese Academy of Sciences research Center for Clean Energy and Power Chinese Academy of Sciences

As gas recirculation constitutes a fundamental condition for the realization of MILD combustion, it is necessary to determine gas recirculation ratio before designing MILD combustor. MILD combustion model with gas recirculation was used in this simulation work to evaluate the effect of fuel type and pressure on threshold gas recirculation ratio of MILD mode. Ignition delay time is also an important design parameter for gas turbine combustor, this parameter is kinetically studied to analyze the effect of pressure on MILD mixture ignition. Threshold gas recirculation ratio of hydrogen MILD combustion changes slightly and is nearly equal to that of 10 MJ/Nm3syngas in the pressure range of 1-19 atm, under the conditions of 298 K fresh reactant temperature and 1373 K exhaust gas temperature, indicating that MILD regime is fuel flexible. Ignition delay calculation results show that pressure has a negative effect on ignition delay time of 10 MJ/Nm3syngas MILD mixture, because OH mole fraction in MILD mixture drops down as pressure increases, resulting in the delay of the oxidation process.

关键词： MILD combustion Gas turbine combustor Syngas Gas recirculation ratio Ignition delay time

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