基于自适应中心加权中值和Goldstein的InSAR干涉图强噪声滤波方法     

王琪洁  朱建军  丁晓利  尹宏杰  李志伟 《测绘通报》2009,(8)

针对现有的滤波方法在处理强噪声干涉图时的不足,提出一种基于自适应中心加权中值和Goldstein的两步干涉图滤波方法。试验结果表明,构造的针对强噪声干涉图的两步滤波法在滤除噪音的同时,可以很好地保存干涉图的条纹信息。与经典的Goldstein方法相比,新方法的滤波效果可以提高22.4%和43.6%。  相似文献   

Irradiated benzene ice provides clues to meteoritic organic chemistry     

Michael P. Callahan  Perry A. Gerakines  Mildred G. Martin  Zan Peeters  Reggie L. Hudson 《Icarus》2013

Aromatic hydrocarbons account for a significant portion of the organic matter in carbonaceous chondrite meteorites, as a component of both the low molecular weight, solvent-extractable compounds and the insoluble organic macromolecular material. Previous work has suggested that the aromatic compounds in carbonaceous chondrites may have originated in the radiation-processed icy mantles of interstellar dust grains. Here we report new studies of the organic residue made from benzene irradiated at 19 K by 0.8 MeV protons. Polyphenyls with up to four rings were unambiguously identified in the residue by gas chromatography–mass spectrometry. Atmospheric pressure photoionization Fourier transform mass spectrometry was used to determine molecular composition, and accurate mass measurements suggested the presence of polyphenyls, partially hydrogenated polyphenyls, and other complex aromatic compounds. The profile of low molecular weight compounds in the residue compared well with extracts from the Murchison and Orgueil meteorites. These results are consistent with the possibility that solid phase radiation chemistry of benzene produced some of the complex aromatics found in meteorites.  相似文献   

Accumulation and Cycle of Heavy Metals in Sonneratia apetala and S. caseolaris Mangrove Community at Futian of Shenzhen, China     

王伯荪  昝启杰  张炜银  王勇军 《海洋通报(英文版)》2003,5(1)

Wetland ecosystem in the Shenzhen Bay is one of the internationally important ecosystems in South China Region. Its core, with the Mai Po Mangrove Nature Reserve in Hong Kong on the one side and the Futian Mangrove Nature Reserve in Shenzhen on the other side, provides habitats for many rare and endangered wild birds, especially for migratory birds[1, 2]. With the economic development in Hong Kong and Shenzhen, a large mount of silt and untreated waste water are poured into the Shenzhe…  相似文献   

鄂西白果园黑色页岩型银钒矿床地球化学特征   总被引：4，自引：0，他引：4  

张乾  董振生  战新志 《矿物学报》1995,(2)

白果园银钒矿床为产于鄂西震旦系陡山坨组黑色页岩中的层状矿床。含矿的黑色伊利石页岩富K、Ti、Cr、Ba，含银40×10－6～299×10－6，V2O50．5％～1．25％，有机碳3％～5％。钒主要赋存在粘土矿物中，银主要在黄铁矿中。黄铁矿Co／Ni值小于1，δ34S值为－11．9‰～－25．8‰，重晶石的δ34S值为＋32．0‰。铅同位素组成构成一条相关性很好的直线，反映出铅的源区年龄为2300～2500Ma，与区域基底变质岩时代一致。地质及地球化学特征均显示矿床属沉积成因。沉积阶段呈吸附状态分散的银和钒，在成岩阶段层内物质自组织过程中进入黄铁矿及粘土矿物中。  相似文献   

辽宁东部中寒武世徐庄期三叶虫动物群     

昝淑芹 《吉林大学学报(地球科学版)》1992,(3)

详细研究了辽宁东部中寒武世徐庄期的三叶虫动物群,包括45个种,分属于23个属和2个亚属.在此基础上,将中寒武统徐庄阶划分了7个生物带,其中新建生物带1个,新划分出生物带2个,并与有关地区进行了对比.  相似文献   

农业干旱模拟研究   总被引：4，自引：2，他引：4       下载免费PDF全文

顾颖  咎霞 《水科学进展》1993,4(4):253-259

根据农田水平衡原理,逐年模拟了农业干旱的发生、发展和缓解的全过程,对所得到的多项表征干旱过程的指标进行了统计分析.参考不同生长期作物缺水对产量影响的试验资料,定量模拟了作物因旱减产的程度,确定了干旱等级.经初步检验,拟合效果较好.  相似文献   

基于MPS无网格方法的孤立波传播的数值模拟          下载免费PDF全文

李绍武  于志安  熊赞 《海洋学报》2007,29(2):137-142

在MPS无网格方法中,引进预定候选粒子集概念用以生成邻接粒子集矩阵,使该部分的机时耗费缩短为引进前的1/11;采用Bi-CGSTAB方法求解压力泊松方程,显著地提高了求解速度.模拟了孤立波在数值波浪水槽中的传播及其与直墙作用时的爬升、回落过程,结果表明模拟波面结果与解析值及实测结果基本相符,针对不同波高的孤立波计算得到的墙前最大爬升值与实测结果也是一致的.  相似文献   

Characterization of defensin gene from abalone <Emphasis Type="Italic">Haliotis discus hannai</Emphasis> and its deduced protein     

洪旭光  孙修勤  郑明刚  曲凌云  昝金东  张进兴 《中国海洋湖沼学报》2008,26(4):375-379

Defensin is one of preserved ancient host defensive materials formed in biological evolution. As a regulator and effector molecule, it is very important in animals＇ acquired immune system. This paper reports the defensin gene from the mixed liver and kidney cDNA library of abalone Haliotis discus hannai Ino. Sequence analysis shows that the gene sequence of full-length cDNA encodes 42 mature peptides （including six Cys）, molecular weight of 4 323 Da, and pI of 8.02. Amino acid sequence homology analysis shows that the peptides are highly similar （70% in common） to other insects defensin. Because of a typical insect-defensin structural character of mature peptide in the secondary structure, the polypeptide named Haliotis discus defensin （hd-def）, a novel of antimicrobial peptides, belongs to insects defensin subfamily. The RT-PCR result of Haliotis discus defensin shows that the gene can be expressed only in the hepatopancreas by Gram-negative and positive bacteria stimulation, which is ascribed to inducible expression. Therefore, it is revealed that the Haliotis discus defensin gene expression was related to the antibacterial infection of Haliotis discus hannai Ino.  相似文献   

基于改进EMD算法和BP神经网络的SST预测研究     

李嘉康  赵颖  廖洪林  李其杰 《气候与环境研究》2017,22(5):587-600

海洋表面温度(Sea Surface Temperature,SST)具有非平稳、非线性的特征,直接将处理平稳数据序列的方法应用到非平稳非线性特征明显的序列上显然是不合适的,预测的误差将会很大。为了提高预测精度,更好地解决非平稳非线性序列预测的问题,本文以东北部太平洋(40°N~50°N、150°W~135°W)区域的月平均海洋表面距平温度为例,首先分别应用集合经验模态分解(EEMD)和互补集合经验模态分解(CEEMD)方法将SST分解为不同尺度的一系列模态分量(IMF),再运用BP(Back Propagation)神经网络模型对每一个模态分量进行分析预测,最后将各IMF预测结果进行重构得到SST的预测值。数值试验的结果表明,CEEMD分解精度比EEMD分解精度高,CEEMD提高了基于BP神经网络的预测精度。系列试验统计分析说明应用这种方法对SST的1年预测是有效的。  相似文献   

Molecular fossils and sources of Cambrian heavy oil of Well Tadong-2 in the Tarim Basin,Xinjiang, China   总被引：1，自引：1，他引：0  

Youjun Tang  Ling Zan 《中国地球化学学报》2009,28(3):314-319

Research on the molecular fossil characteristics of heavy oil from Well Tadong-2 is of great importance to constrain the source of marine crude oils in the Tarim Basin, Xinjiang, China. The authors synthetically applied the isotope mass spectrograph, chromatography and chromatography-mass spectrography to the studies of molecular fossil characteristics of heavy oil from Well Tadong-2 in the Tarim Basin, and the results obtained revealed that heavy oil from Well Tadong-2 is characterized by high gammacerane, high C₂₈ sterane, low rearranged sterane and high C₂₇-triaromatic steroid, these characteristics are similar to those of Cambrian-Lower Ordovician source rocks, demonstrating that Cambrian crude oils came from Cambrian-Lower Ordovician source rocks; condensed compounds (fluoranthene, pyrene, benzo[a]anthracene, bow, benzo fluoranthene, benzopyrene) of high abundance were detected in heavy oil from Well Tadong-2, and the carbon isotopic values of whole oil are evidently heavy, all the above characteristics revealed that hydrocarbons in the crude oils became densified in response to thermal alteration.  相似文献