检索结果-南通市图书馆

The damping model for sea waves covered by oil films of a finite thickness

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2015年第9期34卷 71-77页

作者： zhang yanmin zhang Jie WANG Yunhua MENG Junmin zhang Xi The First Institute of Oceanography State Oceanic Administration College of Information Science and Engineering Ocean University of China

In combination with a wave action balance equation, a damping model for sea waves covered by oil films of a finite thickness is proposed. The damping model is not only related to the physical parameters of the oil film, but also related to environment parameters. Meanwhile, the parametric analyses have been also conducted to understand the sensitivity of the damping model to these parameters. And numerical simulations demonstrate that a kinematic viscosity, a surface/interfacial elasticity, a thickness, and a fractional filling factor cause more significant effects on a damping ratio than the other physical parameters of the oil film. From the simulation it is also found that the influences induced by a wind speed and a wind direction are also remarkable. On the other hand, for a thick emulsified oil film, the damping effect on the radar signal induced by the reduction of an effective dielectric constant should also be taken into account. The simulated results are compared with the damping ratio evaluated by the 15 ENVISAT ASAR images acquired during the Gulf of Mexico oil spill accident.

关键词： sea surface wave oil film of finite thickness damping ratio

The polarimetric features of oil spills in full polarimetric synthetic aperture radar images

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2017年第5期36卷 105-114页

作者： ZHENG Honglei zhang yanmin WANG Yunhua zhang Xi MENG Junmin College of Information Science and Engineering Ocean University of China The First Institute of Oceanography State Oceanic Administration

Compared with single-polarized synthetic aperture radar （SAR） images, full polarimetric SAIl images contain not only geometrical and backward scattering characteristics, but also the polarization features of the scattering targets. Therefore, the polarimetric SAR has more advantages for oil spill detection on the sea surface. As a crucial step in the oil spill detection, a feature extraction directly influences the accuracy of oil spill discrimination. The polarimetric features of sea oil spills, such as polarimetric entropy, average scatter angle, in the full polarimetric SAR images are analyzed firstly. And a new polarimetric parameter P which reflects the proportion between Bragg and specular scattering signals is proposed. In order to investigate the capability of the polarimetric features for observing an oil spill, systematic comparisons and analyses of the multipolarization features are provided on the basis of the full polarimetric SAR images acquired by SIR-C/X-SAR and Radarsat-2. The experiment results show that in C-band SAR images the oil spills can be detected more easily than in L-band SAR images under low to moderate wind speed conditions. Moreover, it also finds that the new polarimetric parameter is sensitive to the sea surface scattering mechanisms. And the experiment results demonstrate that the new polarimetric parameter and pedestal height perform better than other polarimetric parameters for the oil spill detection in the C-band SAR images.

关键词： full polarimetric synthetic aperture radar oil spill detection mulfipolarization features

Cu-10Sn-4Ni-3Pb Alloy Prepared by Crystallization Under Pressure: An Experimental Study

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2013年第2期26卷 199-205页

作者： Kexing SONG Yanjun ZHOU Peifeng ZHAO yanmin zhang Ning BAI School of Materials Science and Engineering Henan University of Science and Technology Henan Key Laboratory of Advanced Non-ferrous Metals Xi'an Jiaotong University

The wear-resistant tin bronze （Cu-10Sn-4Ni-3Pb） with tin content above 8 wt.% prepared by traditional melting and casting process usually defects such as low density, poor properties and segregations. The crystallization under pressure processing of Cu-10Sn-4Ni-3Pb alloy was investigated. The microstructures were observed and analyzed and compared with that by traditional melting and casting process. The results show that the dendrite has obviously disappeared and the dendritic segregation alleviated by using the crystallization under 680 MPa pressure process, in comparison with the remarkably dendrite microstructure and severe as-cast defects of alloy prepared by traditional melting and casting technology. Based on the experimental study, the properties and microstructures of Cu-10Sn-4Ni-3Pb tin bronze prepared by crystallization under pressure have been improved significantly.

关键词： Cu-10Sn-4Ni-3Pb bronze Crystallization under pressure Microstructure Segregation

EGFR/cell membrane chromatography-online-high performance liquid chromatography/mass spectrometry method for screening EGFR antagonists from Radix Angelicae Pubescentis

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2010年第11期53卷 2357-2362页

作者： SiCen Wang Meng Sun yanmin zhang Jie zhang LangChong He Xi An Jiao Tong Univ Sch Med Minist Educ Key Lab Environm & Genes Related Dis Xian 710061 Peoples R China

The intracellular kinase domains of the epidermal growth factor receptor(EGFR) in some tumor cells are significant targets for drug *** have developed a new EGFR cell membrane chromatography(EGFR/CMC)-online-high performance liquid chromatography/mass spectrometry(HPLC/MS) method for screening anti-EGFR antagonists from medicinal herbs such as Radix Angelicae *** this study,the HEK293 EGFR cells with high expression of EGFR were used to prepare cell membrane stationary phase(CMSP) in the EGFR/CMC *** retention fractions on the EGFR/CMC model were directly analyzed by combining a 10 port columns switcher with a HPLC/MS system *** a result,osthole from Radix Angelicae Pubescentis was found to be the active component acting on EGFR like dasatinib as the control *** was a good relationship between their inhibiting effects on EGFR secretion and HEK293 EGFR cell growth in *** new EGFR/CMC-online-HPLC/MS method can be applied for screening anti-EGFR antagonists from TCMs,for instance,Radix Angelicae *** will be a useful method for drug discovery with natural medicinal herbs as a leading compound resource.

关键词： EGFR cell membrane chromatography high performance liquid chromatography/mass spectrometry anti-EGFR antagonists Radix Angelicae Pubescentis

Targets detecting in the ocean using the cross-polarized channels of fully polarimetric SAR data

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2015年第1期34卷 85-93页

作者： WANG Yunhua LIU Xiaoyan LI Huimin zhang yanmin Ocean Remote Sensing Institute Ocean University of China College of Information Science & Engineering Ocean University of China The First Institude of Oceanography

Azimuth ambiguities （ghost targets） discrimination is of great interest with the development of a synthet- ic aperture radar （SAR）. And the azimuth ambiguities are often mistaken as actual targets and cause false alarms. For actual targets, HV channel signals acquired by a fully polarimetric SAR are approximately equal to a VH channel in magnitude and phase, i.e., the reciprocity theorem applies, but shifted in phase about ±π for the first-order azimuth ambiguities. Exploiting this physical behavior, the real part of the product of the two cross-polarized channels, i.e. （SHVSVH）, hereafter called A12r, is employed as a new parameter for a target detection at sea. Compared with other parameters, the contrast of A12r image between a target and the surrounding sea surface will be obviously increased when A12r image is processed by mean filtering algo- rithm. Here, in order to detect target with constant false-alarm rates （CFARs）, an analytical expression for the probability density function （pdf） ofA12r is derived based on the complexWishart-distribution. Because a value of A12r is greater/less than 0 for real target/its azimuth ambiguities, the first-order azimuth ambiguities can be completely removed by this A12r-based CFAR technology. Experiments accomplished over C-band RADARSAT-2 fully polarimetric imageries confirm the validity.

关键词： azimuth ambiguities polarimetric SAR CFAR detection algorithm

The measurement of sea surface profile with X-band coherent marine radar

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2015年第9期34卷 65-70页

作者： WANG Yunhua LI Huimin zhang yanmin GUO Lixin Ocean Remote Sensing Institute Ocean University of China Department of Physics Ocean University of China School of Physics and Optoelectronic Engineering Xidian University

The line-of-sight velocity of scattering facets is related to the Doppler signals of X-band coherent marine radar from the oceanic surface. First, the sign Doppler Estimator is applied to estimate the Doppler shift of each radar resolution cell. And then, in terms of the Doppler shift, a retrieval algorithm extracting the vertical displacement of the sea surface has been proposed. The effects induced by radar look-direction and radar spatial resolution are both taken into account in this retrieval algorithm. The comparison between the sea surface spectrum of buoy data and the retrieved spectrum reveals that the function of the radar spatial resolution is equivalent to a low pass filter, impacting especially the spectrum of short gravity waves. The experimental data collected by McMaster IPIX radar are also used to validate the performance of the retrieval algorithm. The derived significant wave height and wave period are compared with the in situ measurements, and the agreement indicates the practicality of the retrieval technology.

关键词： X-band coherent marine radar Doppler signal sea surface profile retrieval method

The influences of environmental factors on the air-sea coupling coefficient

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2022年第2期41卷 147-155页

作者： yanmin zhang Yifan Wang Yunhua Wang Yining Bai Chaofang Zhao College of Information Science and Engineering Ocean University of ChinaQingdao 266100China Laboratory for Regional Oceanography and Numerical Modeling Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China

The response relationship between equivalent neutral wind speed anomaly(ENWSA)and sea-air temperature difference anomaly(SATDA)has been analyzed over four typical sea regions,i.e.,the Kuroshio Extension,the Gulf Stream,the Brazil-Malvinas Confluence and the Agulhas Return *** results show that ENWSA is more sensitive to SATDA than sea surface temperature anomaly(SSTA),which implies that SATDA seems to be a more suitable parameter than SSTA to analyze the mesoscale air-sea ***,the slope of the linear relation between ENWSA and SATDA is defined as the air-sea coupling *** is found that the values of the coupling coefficient over the four typical sea areas have obvious seasonal variations and geographical *** order to reveal the reason of the seasonal variation and geographical difference of the coupling coefficient,the influences of some environmental background factors,such as the spatially averaged sea surface temperature(SST),the spatially averaged air temperature,the spatially averaged sea-air temperature difference and the spatially averaged equivalent neutral wind speed,on the coupling coefficient are discussed in *** results reveal that the background sea-air temperature difference is an important environmental factor which directly affects the magnitude of the coupling coefficients,meanwhile,the seasonal and geographical variations of the coupling coefficient.

关键词： air-sea coupling coefficient SST equivalent neutral wind speed sea-air temperature difference

A new model for Doppler shift of C-band echoes backscattered from sea surface

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2023年第6期42卷 100-111页

作者： Jianbo Cui Yunhua Wang yanmin zhang Huimin Li Wenzheng Jiang Yushi zhang Xin Li College of Information Science and Engineering Ocean University of ChinaQingdao 266100China Qingdao National Laboratory for Marine Science and Technology Qingdao 266237China School of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 210044China First Institute of Oceanography Ministry of Natural ResourcesQingdao 266061China National Key Laboratory of Electromagnetic Environment/China Research Institute of Radiowave Propagation Qingdao 266107China

Within the framework of the two-scale scattering model,the Doppler shift of C-band radar return signals from the nonlinear sea surface are numerically *** an analytical approximation method,the Bragg resonance scattering method cannot accurately describe the backscattering field from sea ***,in the twoscale scattering model,more accurate scattering coefficient(the normalized radar cross section,NRCS)evaluated by the C-band dual-polarized(HH/VV)empirical geophysical model function(CSAR model)is employed to replace the traditional Bragg NRCS to weight the Doppler *** numerical results indicate that there are obvious differences between the Doppler shift weighted by the CSAR NRCS and that weighted by the traditional Bragg *** hydrodynamic modulation of the large-scale waves is one of the important factors that affect the difference between the Doppler shift predicted in upwind and downwind *** the relaxation rate in the hydrodynamic modulation is set to be the angular frequency of the dominant water waves,the Doppler shift predicted by the numerical method can fit the results of the empirical model(C-band empirical geophysical model function,CDOP)well at moderate wind *** low wind condition,the comparison shows that the empirical CDOP model appears to overestimate the Doppler *** order to facilitate the application,at the end of this paper a semi-empirical CSAR-DOP model,which is a polynomial fitting formula,is developed for evaluating the Doppler shift of C-band signals from time varying sea surface.

关键词： Doppler shift microwave scattering numerical simulation

Osteoblast Behavior on Hierarchical Micro-/Nano-Structured Titanium Surface

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2011年第3期8卷 234-241页

作者： Weiyan Meng yanmin Zhou Yanjing zhang Qing Cai Liming Yang Jinghui Zhao Chunyan Li School of Stomatology Jilin University Changchun 130021 P. R. China

In the present work, osteoblast behavior on a hierarchical micro-/nano-structured titanium surface was investigated. A hi- erarchical hybrid micro-/nano-structured titanium surface topography was produced via Electrolytic Etching （EE）. MG-63 cells were cultured on disks for 2 h to 7 days. The osteoblast response to the hierarchical hybrid micro-/nano-structured titanium surface was evaluated through the osteoblast cell morphology, attachment and proliferation. For comparison, MG-63 cells were also cultured on Sandblasted and Acid-etched （SEA） as well as Machined （M） surfaces respectively. The results show signifi- cant differences in the adhesion rates and proliferation levels of MG-63 cells on EE, SLA, and M surfaces. Both adhesion rate and proliferation level on EE surface are higher than those on SLA and M surfaces. Therefore, we may expect that, comparing with SLA and M surfaces, bone growth on EE surface could be accelerated and bone formation could be promoted at an early stage, which could be applied in the clinical practices for immediate and early-stage loadings.

关键词： dental implant osteoblast hierarchical micro-/nano-structure surface treatment electrolytic etching