检索结果-南通市图书馆

A statistical approach for determining the environment impact of surface sediments from the Dongting Lake area, central China

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal Of Geochemistry 2009年第1期28卷 97-104页

作者： yao zhigang Key Laboratory of Continental Dynamics Ministry of Education/Department of Geology Northwest University Xi ＇an 710069 China School of Petroleum Resources Xi＇an Shiyou University Xi＇an 710065 China

The Dongting Lake, the second biggest freshwater lake in China, consists of three wetlands of national importance, namely the East Dongting Lake, the South Dongting Lake, and the West Dongting Lake. Surface sediments were sampled from 57 locations across the lake. Nutrient concentrations [total organic carbon (TOC), total N (TN) and total P (TP)] and 16 element concentrations (Al, As, B, Ca, Cd, Cr, Cu, K, Fe, Hg, Mn, Ni, Pb, Si, Ti and Zn) in the sediments were measured to investigate the impact of industrialization along the lake’s coastline and several tributaries on the profiles of nutrients and heavy metals in the lake’s surface sediments. R-mode cluster analysis (CA) was used to integrate geochemical data. The result showed that euthophication of the Dongting Lake resulted mainly from TN and TOC. The main polluting trace metals are Hg, As, Cd, Zn, Pb and Mn, which are largely adsorbed on clay minerals or Fe/Mn oxides, or deposited as carbonates. Principal component analysis (PCA) revealed the source of micropollutants. The worst affected district by heavy metals is the East Dongting Lake, the pollution sources may originate mainly from the Xiangjiang drainage area. The results demonstrated that multivariate methods are the potentially great tools for the interpretation of the environmental data on lake sediments.

关键词：重金属沉积物多元方差分析洞庭湖地球化学

Periodic and chaotic dynamics of composite laminated piezoelectric rectangular plate with one-to-two internal resonance

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2009年第3期52卷 731-742页

作者： ZHANG Wei yao zhigang yao MingHui College of Mechanical Engineering Beijing University of TechnologyBeijing 100124China

The bifurcations and chaotic dynamics of a simply supported symmetric cross-ply composite lami- nated piezoelectric rectangular plate are studied for the first time, which are simultaneously forced by the transverse, in-plane excitations and the excitation loaded by piezoelectric layers. Based on the Reddy’s third-order shear deformation plate theory, the nonlinear governing equations of motion for the composite laminated piezoelectric rectangular plate are derived by using the Hamilton’s principle. The Galerkin’s approach is used to discretize partial differential governing equations to a two-degree- of-freedom nonlinear system under combined the parametric and external excitations. The method of multiple scales is employed to obtain the four-dimensional averaged equation. Numerical method is utilized to find the periodic and chaotic responses of the composite laminated piezoelectric rectangular plate. The numerical results indicate the existence of the periodic and chaotic responses in the aver- aged equation. The influence of the transverse, in-plane and piezoelectric excitations on the bifurca- tions and chaotic behaviors of the composite laminated piezoelectric rectangular plate is investigated numerically.

关键词： composite laminated piezoelectric rectangular plate third-order shear deformation parametric excitation bifurcation chaos

Multi-pulse orbits dynamics of composite laminated piezoelectric rectangular plate

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2011年第8期54卷 2064-2079页

作者： yao MingHui ZHANG Wei yao zhigang College of Mechanical Engineering Beijing University of Technology Beijing 100124 China

The multi-pulse orbits and chaotic dynamics of a simply supported laminated composite piezoelectric rectangular plate under combined parametric excitation and transverse excitation are studied in detail. It is assumed that different layers are perfectly bonded to each other with piezoelectric actuator patches embedded. The nonlinear equations of motion for the laminated composite piezoelectric rectangular plate are derived from von Karman-type equation and third-order shear deformation plate theory of Reddy. The two-degree-of-freedom dimensionless equations of motion are obtained by using the Galerkin approach to the partial differential governing equation of motion for the laminated composite piezoelectric rectangular plate. The four-dimensional averaged equation in the case of primary parametric resonance and 1:3 internal resonances is obtained by using the method of multiple scales. From the averaged equation, the theory of normal form is used to find the explicit formulas of normal form. Based on the normal form obtained, the energy phase method is utilized to analyze the multi-pulse global bifurcations and chaotic dynamics for the laminated composite piezoelectric rectangular plate. The analysis of the global dynamics indicates that there exist multi-pulse jumping orbits in the perturbed phase space of the averaged equation. Based on the averaged equation obtained, the chaotic motions and the Shilnikov type multi-pulse orbits of the laminated composite piezoelectric rectangular plate are also found by numerical simulation. The results obtained above mean the existence of the chaos in the Smale horseshoe sense for the simply supported laminated composite piezoelectric rectangular plate.

关键词： laminated composite piezoelectric rectangular plates multi-pulse orbit chaotic dynamics energy phase method

Higher-dimensional chaotic dynamics of a composite laminated piezoelectric rectangular plate

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2009年第12期52卷 1989-2000页

作者： ZHANG Wei GAO MeiJuan yao MingHui yao zhigang College of Mechanical Engineering Beijing University of TechnologyBeijing 100124China

The analysis on the chaotic dynamics of a six-dimensional nonlinear system which represents the averaged equation of a composite laminated piezoelectric rectangular plate is given for the first time. The theory of normal form and the energy-phase method are combined to investigate the higher-dimen-sional chaotic dynamics of the composite laminated piezoelectric rectangular plate. Firstly,the theory of normal form is used to reduce the six-dimensional averaged equation to the simpler normal form. Then,the energy-phase method is extended to analyze the global bifurcations and chaotic dynamics of a six-dimensional nonlinear system. The analysis results indicate that there exist the homoclinic bi-furcation and Shilnikov type multi-pulse chaos for the composite laminated piezoelectric rectangular plate. Finally,numerical simulations are also used to investigate the nonlinear dynamic characteristics of the composite laminated piezoelectric rectangular plate. The results of numerical simulations also demonstrate that there exist the chaotic motions and the multi-pulse jumping orbits of the composite laminated piezoelectric rectangular plate.

关键词： composite laminated piezoelectric rectangular plate normal form energy-phase method numerical simulation jumping orbits chaotic motion

Synergistic Use of AIRS and MODIS for Dust Top Height Retrieval over Land

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2015年第4期32卷 470-476页

作者： yao zhigang Jun LI ZHAO Zengliang Beijing Institute of Applied Meteorology Cooperative Institute for Meteorological Satellite Studies University of Wisconsin-Madison

It is nontrivial to extract the dust top height（DTH） accurately from passive instruments over land due to the complexity of the surface conditions. The Moderate Resolution Imaging Spectroradiometer（MODIS） deep blue（DB） algorithm can be used to infer the aerosol optical depth（AOD） over high-reflective surfaces. The Atmospheric Infrared Sounder（AIRS） can simultaneously obtain the DTH and optical depth information. This study focuses on the synergistic use of AIRS observations and MODIS DB results for improving the DTH by using a stable relationship between the AIRS infrared and MODIS DB AODs. A one-dimensional variational（1DVAR） algorithm is applied to extract the DTH from AIRS. Simulation experiments indicate that when the uncertainty of the dust optical depth decreases from 50% to 20%, the improvement of the DTH retrieval accuracy from AIRS reaches 200 m for most of the assumed dust conditions. For two cases over the Taklimakan Desert, the results are compared against Cloud-Aerosol Lidar with Orthogonal Polarization（CALIOP） measurements. The results confirm that the MODIS DB product could help extract the DTH over land from AIRS.

关键词： AIRS MODIS dust height Cloud-Aerosol Lidar with Orthogonal Polarization

Pigment signatures of some diatoms isolated from China seas

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2006年第1期25卷 108-118页

作者： yao Peng YU zhigang DENG Chunmei College of Chemistry and Chemical Engineering Ocean University of China Qingdao 266003 China

The photosynthetic pigments of 12 species （14 strains） of cultured diatoms from six genera under specific conditions were examined by the HPLC. The diatom genera were Skeletonema, Thalassiosira, Chaetoceros, Nitzschla, Phaeodactylum and Meuniera. All strains were isolated from China seas and most of them were from the Jiaozhou Bay, China. Fifteen pigments were identified and eight of them were various chlorophyll a derivatives. Chlorophyll a, c2 and c1 and the carotenoids fucoxanthin, diadinoxanthin, diatoxanthin and β, β-carotene existed in all species. The ratios of each pigment to chlorophyll a were compared with the results in literatures. The pigment ratios of this study generally fall within the ranges reported by the literatures although the maximum ratio of fucoxanthin to chlorophyll a was higher and the ratios of chlorophyll c and diatoxanthin to chlorophyll a were low. The pigment ratios are useful to understanding the pigment signatures of diatoms in the Jiaozhou Bay, China, and to setting up the chemotaxonomic method of phytoplankton in these sea areas.

关键词： diatoms pigment HPLC ratio Jiaozhou Bay

Air flow and gas dispersion in the forced ventilation of a road tunnel during construction

在线全文

学校读者我要写书评

暂无评论

Underground Space 2019年第2期4卷 168-179页

作者： Yong Fang zhigang yao Shuai Lei Key Laboratory of Transportation Tunnel Engineering Ministry of EducationSouthwest Jiaotong UniversityChengduChina School of Civil Engineering Southwest Jiaotong UniversityChengduChina

Forced ventilation is typically used in the construction of tunnels since it is an economical method to provide high amounts of fresh *** velocity and pollutant concentration near the work face are determined by the ventilation *** the study,field measurement of air velocity was performed,and computational fluid dynamics(CFD)models were constructed to investigate airflow near the work face and predict the gas distribution in a gas tunnel *** effects of the distance between the air duct exit and the work face(L_(1))were evaluated by analyzing the flow field and pollutant *** evaluation shows that the ventilation efficiency improves if L_(1) does not exceed 15 m in a road tunnel with full-face *** respect to a road tunnel with benching excavation,the effects of bench length(L_(2))are analyzed,and the results of the analysis indicate that ventilation efficiency is optimal when L_(2)=5 m and L_(2)=10 m and the air-duct diameter corresponds to 1.6 *** CFD results fit the field measurement significantly well,and the current ventilation system in the construction exhibits a relatively high *** findings of the study aid practitioners in optimizing ventilation efficiency.

关键词： Tunnel construction Forced ventilation Ventilation arrangement Fluid field Hazardous gases Numerical simulation

Case analysis of water exchange between the Bohai and Yellow Seas in response to high winds in winter

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Oceanology and Limnology 2020年第1期38卷 30-41页

作者： JU Xia MA Chao yao zhigang BAO Xianwen College of Oceanic and Atmospheric Sciences Ocean University of ChinaQingdao 266100China First Institute of Oceanography Ministry of Natural Resources(MNR)Qingdao 266061China Key Laboratory of Marine Science and Numerical Modeling Ministry of Natural Resources(MNR)Qingdao 266061China Pilot National Laboratory for Marine Science and Technology Qingdao 266237China

Based on the data from a special project titled China's Offshore Marine Integrated Investigation and Evaluation as well as Regional Ocean Modeling Systems(ROMS)diagnostic numerical model,we studied the influence of high wind processes on the circulation and water exchange between the Bohai and Yellow Seas(BYS)in *** results show that the vertical structure of the Yellow Sea Warm Current(YSWC)is relatively uniform under condition of high winds,showing obvious barotropic ***,this flow is not a stable mean flow,showing strong paroxysmal and reciprocating characteristics.A comparison of the changes in sea level suggests that the intensity of the northwards upwind flow is consistent with the abnormal fluctuations in the sea *** indicates that the upwind flow is closely related to the water exchange between the *** impact of high wind processes on the water exchange between the BYS is *** can make the flux through the Bohai Strait,as well as that through the mouth of each constituent bay(i.e.,Liaodong Bay,Bohai Bay,and Laizhou Bay)far greater than usual,resulting in a significant increase in the water exchange *** exchange capacity,which is about 8%of the total volume of the Bohai Sea,can be completed in a few ***,the water exchange of the Bohai Sea may be completed by only a few occasional high wind processes in winter.

关键词： high wind Yellow Sea Warm Current (YSWC) sea level rise or drop water exchange

Application of Aircraft Observations over Beijing in Cloud Microphysical Property Retrievals from CloudSat

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2014年第4期31卷 926-937页

作者： WANG Lei LI Chengcai yao zhigang ZHAO Zengliang HAN zhigang WEI Qiang Department of Atmospheric and Oceanic Sciences School of Physics Peking University Beijing Institute of Applied Meteorology

Cloud microphysical property retrievals from the active microwave instrument on a satellite require the cloud droplet size distribution obtained from aircraft observations as a priori data in the iteration *** cloud lognormal size distributions derived from 12 flights over Beijing,China,in 2008-09 were characterized to evaluate and improve regional CloudSat cloud water content *** present the distribution parameters of stratiform cloud droplet （diameter ＜500 tm and ＜1500 μm） and discuss the effect of large particles on distribution parameter *** on three retrieval schemes with different lognormal size distribution parameters,the vertical distribution of cloud liquid and ice water content were derived and then compared with the aircraft *** results showed that the liquid water content （LWC） retrievals from large particle size distributions were more consistent with the vertical distribution of cloud water content profiles derived from in situ data on 25 September *** then applied two schemes with different a priori data derived from flight data to CloudSat overpasses in northern China during April-October in 2008 and *** CloudSat cloud water path （CWP） retrievals were compared with Moderate Resolution Imaging Spectroradiometer （MODIS） liquid water path （LWP） *** results indicated that considering a priori data including large particle size information can significantly improve the consistency between the CloudSat CWP and MODIS *** results strongly suggest that it is necessary to consider particles with diameters greater than 50 tm in CloudSat LWC retrievals.

关键词： CloudSat liquid water content a priori data aircraft observations