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971.
基于地面试验的植被覆盖率估算模型及其影响因素研究 总被引:1,自引:0,他引:1
以植被覆盖率的遥感反演为研究主线,以玉米作物为例,在基于地面试验获得作物光谱、叶面积指数和多角度覆盖率的基础上,对目前普遍采用的两种基于植被指数的植被覆盖率估算模型进行了精度比较,同时对植被覆盖率反演的影响因子(叶面积指数、植被空间分布和观测角度)进行了分析.由此得到:估算植被覆盖率的最优植被指数为归一化植被指数;叶面积指数对植被指数与植被覆盖率间关系的影响随植被的生长不断增大;植被空间分布对垂直覆盖率的估算影响很小.对于多角度覆盖率有这样的规律,即在4种空间分布下,以0°观测天顶角(VZA)为中心,在相反方位角上随VZA的增加,覆盖率值基本呈对称分布;在玉米刚出苗时,覆盖率随VZA的增加而增加,当VZA=0°时达到最小值,而随着玉米的进一步生长,4种分布条件下覆盖率随VZA的增加反而降低,在VZA=0°时达到最大值. 相似文献
972.
Banana is one of the main economic agrotypes in Zhangzhou, Fujian Province. The multi-temporal ENVISAT ASAR data with different
polarization are used to classify the banana fields in this paper. Principal component analysis (PCA) was applied for six
pairs of ASAR dual-polarization data. For its large leaves, banana has high backscatter. So the value of banana fields is
high and shows very bright in the 1st component, which makes it much easier for banana fields extraction. Dual-polarization
data provide more information, and the VV and VH backscatter of banana show different characters with other land covers. Based
on the analysis of the radar signature of banana fields and other land covers and the 1st component, banana fields are classified
using object-oriented classifier. Compared to the field survey data and ASTER data, the accuracy of banana fields in the study
area is 83.5%. It shows that the principal component analysis provides the useful information in SAR images analysis and makes
the extraction of banana fields easier.
Supported by the Program for New Century Excellent Talents in University (NCET-05-0573), Fujian Science and Technology Project
(No.2006I0018), the Science Project of the Education Department of Fujian Province(No. 2006F5022). 相似文献
973.
三维城市模型的研究与实践(英文) 总被引:3,自引:0,他引:3
The way we interact with spatial data has been changed from 2D map to 3D Virtual Geographic Environment (VGE). Three-dimensional
representations of geographic information on a computer are known as VGE, and in particular 3D city models provide an efficient
way to integrate massive, heterogenous geospatial information and georeferenced information in urban areas. 3D city modeling
(3DCM) is an active research and practice topic in distinct application areas. This paper introduces different modeling paradigms
employed in 3D GIS, virtual environment, and AEC/FM. Up-to-date 3DCM technologies are evolving into a data integration and
collaborative approach to represent the full spatial coverage of a city, to model both aboveground and underground, outdoor
and indoor environments including man-made objects and natural features with 3D geometry, appearance, topology and semantics.
Supported by the National Natural Science Foundation of China ( No. 40871212, No. 40671158), the Leading Academic Discipline
Project of Shanghai Educational Committee( No.J50104). 相似文献
974.
NUFFT-Based Iterative Reconstruction Algorithm for Synthetic Aperture Imaging Radiometers 总被引:2,自引:0,他引:2
Synthetic aperture imaging radiometers (SAIRs) are powerful sensors for high-resolution observation of the Earth at low microwave frequencies. However, the future application of this new technology is limited by its large number of element antennas and receiving channels. In order to further reduce the complexity of the whole system, the circular and rotating array configurations have been proposed. Their disadvantages lie primarily in more complicated image reconstruction, because the conventional fast Fourier transform (FFT) method could not be used directly for image reconstruction. This letter introduces an iterative method for the reconstruction of radiometric brightness temperature maps from nonuniform visibility function samples. This method combines the conjugate gradient algorithm with min-max nonuniform FFT approach, which has been shown to provide considerably improved image quality relative to the traditional gridding method. Simulations for SAIRs were performed and showed better image quality in comparison to the traditional frequency interpolation method. 相似文献
975.
INTR0DUCnONErhailake,thesecondlargestlakeintheYUnnanPlateauinS0uthWstChina,islo-catedinDaliDefecthe25035'to25"58'N,looo05't0l(X)o07'E(Fig.l)-The40kInlong3-9kInwidelakeisnaInedafteritsearlikeshape.ItsbasicchimteristicsaregiveninTablel.EtheibeeisampicalriftlakeintheDalibasinwhichdeveloPedalongtheYuaniangHongheThewestsideofthebasinisformedbytheDiancangMountainwhichconsists0frock(PrecaInbrianschistandgneissandMiocenemetaInrphiclimestone).TheseisndcallystillactivemoUntainrangrisab0ut… 相似文献
976.
INTR0DUCnONAlloycoatingscandetivelyproteCtsteelagainstcormsioninseri0uscormsionenvir-orunent,suchasthedrinesplashandtidalzones-TwoInainhodiptincaldrinumalloycOaingswidelyusedcommroiallyareGalfancoaing(contalningZn-5wt%kl-us)devel-oPedbytheIntemaionaltalZincReenhheZaionandhocoating(c0n-talningZn-55Wt%Al-1.6Wt%Si)develoPedbytheBethlehemSteelCorpOration-Anewrinc-basedalloycOaingdevel0PedbyNortheaStemUniversityisdiscussedinthesPaperbyelecthehendcalmethod.FromSun(l996),welmOWthecorms… 相似文献
977.
Heat shocks effectively produced triploids inPenaeus chinensis. Fertilized eggs heat shocked (28–32°C) for 8 to 16 minutes, starting from 8 to 20 minutes after spawning, resulted in triploidy
induction rates of 39%–75%. Several triploid populations were cultured to 10 cm. In a triploid population, two kinds of ovaries
were observed. Histological examination showed apparent differences between these two kinds of ovaries, whereas among male
shrimp, there were no such differences.
Contribution No. 3465 from the Institute of Oceanology. Chinese Academy of Sciences.
The study was supported by the International Foundation for Science, Asian Fisheries Society and Chinese Climbing Project
PDB 6–2, and Chinese National 863 Project (No. 863-819-01-05). 相似文献
978.
朱龙 《广东海洋大学学报》1999,(1)
1993年7月至1998年8月对蓬莱沿海定置网渔获的鱼类进行初步调查,结果表明,蓬莱沿海鱼类共有137种,分别隶属于59科108属。根据其适温类型可分为暖水性鱼类34种,占总数的24.82%;暖温性鱼类83种,占总数的60.58%;冷温性鱼类20种,占总数的14.60%。根据食性类型,可分为3类,其中游泳动物食性的鱼类36种,占总数的26.28%;浮游动物食性有22种,占总数的16.06%;底栖动物食性79种,占总数的57.66%.从栖息生境的多样性来看,可分为中上层鱼类38种,占总数的27.74%;近底层鱼类25种,占总数的18.25%;底层鱼类64种,占总数的46.71%;岩礁性鱼类10种,占总数的7.30%。并就渔业开发与保护提出了建议。 相似文献
979.
采用室内水泥池及活饵培育配套技术进行尖吻鲈苗种阶段工厂化育苗。投放刚孵化出膜的仔鱼160万尾,经室内池8d的培育,成活率为90%;经13d的培育其规格超过1cm,成活率为56.9%;经24d的培育平均规格达2cm左右,平均成活率为50%,共育出80万尾。苗种生长快,体质健壮,成活率高。关键技术是:基础设施配套;采用不同活饵,做到适口、及时转化、足量;定期过筛分级培育;水质控制良好;注意防病。2cm以上鱼种阶段采用多种方式培育,经15~20d的饲养,规格达3~4cm,平均成活率为65%~75%。 相似文献
980.
Four comparative experiments and some supplementary experiments were conducted to examine the role of meridional wind stress anomalies and heat flux variability in ENSO simulations by using a high-resolution Ocean General Circulation Model (OGCM). The results indicate that changes in the direction and magnitude of meridional wind stress anomalies have little influence on ENSO simulations until meridional wind stress anomalies are unrealistically enlarged by a factor of 5.0. However, evidence of an impact on ENSO simulations due to heat flux variability was found. The simulated Nino-3 index without the effect of heat flux anomalies tended to be around 1.0° lower than the observed, as well as the control run, during the peak months of ENSO events. 相似文献