Hyperspectral feature analysis of chlorophyll a and suspended solids using field measurements from Taihu Lake,eastern China     

《水文科学杂志》2013,58(4):808-824

Abstract

We report results of three field campaigns conducted at 39 stations. At each station, we measured reflectance spectra in situ and collected water samples for measuring chlorophyll a (CHL) and suspended solids (SS) concentrations in the laboratory. To identify the indicative bands and develop suitable estimation models for CHL (C _CHL) and SS (C _SS) concentrations in Taihu Lake, a spectral-feature method and a derivative method were applied. The following conclusions were drawn: (a) the critical C _CHL and C _SS probably causing their spectral variation are, respectively: 0, 10, 50 and 75 μg L^?1, and 0, 10, 50 and 100 mg L^?1; (b) the derivative method is better than the spectral-feature method for estimating C _CHL and C _SS; (c) the optimal variable for CHL is a reflectance second-order derivative at 501 nm or a reflectance first-order derivative at 698 nm; the optimal variable for SS can change when its concentration is low and the range is narrow; otherwise, the optimal variable is a reflectance first-order derivative at 878 nm; and (d) the CHL and SS have an effect on one another's retrieval. The C _CHL estimation accuracy would benefit from narrowing the C _SS range. With C _CHL increasing and its range broadening, the corresponding C _SS estimation accuracy decreases gradually.  相似文献   

Finite element modeling of heating phenomena of cracks excited by high-intensity ultrasonic pulses     

陈赵江  郑江  张淑仪  米小兵  郑凯 《海洋学报(英文版)》2010,29(11)

A three-dimensional thermo-mechanical coupled finite element model is built up to simulate the phenomena of dynamical contact and frictional heating of crack faces when the plate containing the crack is excited by high-intensity ultrasonic pulses. In the finite element model, the high-power ultrasonic transducer is modeled by using a piezoelectric thermal-analogy method, and the dynamical interaction between both crack faces is modeled using a contact-impact theory. In the simulations, the frictional heating taking place at the crack faces is quantitatively calculated by using finite element thermal-structural coupling analysis, especially, the influences of acoustic chaos to plate vibration and crack heating are calculated and analysed in detail. Meanwhile, the related ultrasonic infrared images are also obtained experimentally, and the theoretical simulation results are in agreement with that of the experiments. The results show that, by using the theoretical method, a good simulation of dynamic interaction and friction heating process of the crack faces under non-chaotic or chaotic sound excitation can be obtained.  相似文献   

波伏棱（Povlen）型羟基纤蛇纹石的谱学研究     

朱和宝  江绍英  邵涵如  吴卫芳 《岩石矿物学杂志》1989,8(1):43-53

波伏棱型羟基纤蛇纹石是波伏棱型纤蛇纹石矿物的新变种,本文报导它的吸收光谱、红外光谱、穆斯堡尔谱、电子顺磁共振谱和核磁共振谱。 研究表明,吸收光谱是Fe~(3 )和Fe~(2 )的晶场跃迁以及Fe~(2 )→Fe~(3 )的荷移跃迁引起的;红外光谱是OH和Si-O的伸缩振动、OH转动以及Mg-O和Si-O的弯曲振动引起的;穆斯堡尔谱是Fe~(2 )_(八面体)、Fe~(3 )_(八面体)和Fe~(3 )_(四面体)引起的;电子顺磁共振谱是Mn~(2 )_(八面体)、Fe~(3 )_(八面体)和Fe~(3 )_(四面体)引起的;核磁共振谱是管道水,镁八面体和硅氧四面体上的OH引起的;矿物加热到825℃时,结构开始破坏并出现镁橄榄石相。 此外,本文还解释了该蛇纹石颜色的本质,阐明了上述过渡金属离子和OH在该矿物中的结构环境。  相似文献   

Intercomparison of NO column measurements during MAP/GLOBUS 1985     

R. L. McKenzie  W. A. Matthews  Y. Kondo  R. Zander  Ph. Demoulin  P. Fabian  D. G. Murcray  F. J. Murcray  O. Lado-Bordowsky  C. Camy-Peyret  H. K. Roscoe  J. A. Pyle  R. D. McPeters 《Journal of Atmospheric Chemistry》1988,7(4):353-367

Column measurements of nitric oxide were made using several techniques during the MAP/GLOBUS campaign in France in September 1985. The data sets are nearly co-located and simultaneous, therefore allowing a valid intercomparison of the various measurement methods. The range of altitudes sampled differs from instrument to instrument. This complicates the comparison because the data sets are to some extent complementary. The NO distributions apparently vary significantly from day to day, and possibly over shorter timescales. Changes in dynamics may be responsible for these variations. The results from the instruments which measure in the infrared and the ultraviolet are self-consistent, and show good agreement with photochemical predictions. On 19 September, when the intercomparison was made, the profile measured by the in-situ chemiluminescent instrument differed significantly from the predicted profile, and the measured columns were generally higher.  相似文献   

红外光谱方法在找金中的应用综述   总被引：4，自引：1，他引：4  

张保民 《地质科技情报》1994,13(4):98-102

从四个方面介绍了红外光谱在金矿普查评价中的应用：石英薄片中气液包裹体与金的关系研究；石英中杂质阳离子与金的关系研究；黄铁矿与金的关系研究；金矿区氧化带和矿带共生组合矿物研究。  相似文献   

遥感特征信息提取的综合分析——以红外细分波段新疆铁木尔特航带矿化特征信息提取为例     

迟国彬  丁暄  李岩 《遥感学报》1991,(1)

本文以红外细分波段新疆铁木尔特航带为例,依据不同地质体各自的光谱特征,运用主成分分析、多种信息复合等技术与综合分析方法,使该地段的矿化特征提取收到了良好效果。 本航带的矿化特征信息在图像处理结果中表现为黄色异常色调。它反映了当地多金属成矿带中二氧化硅含量低、全铁含量较高的岩矿矿化特征。团块状黄色异常色调表示出地表出露的铁帽、磁铁矿化和矽卡岩化的分布状况。野外验证表明,黄色调的分布地域与实地的地表矿化范围相吻合。 遥感特征信息提取的综合分析方法包括信息基本特征分析、图像处理、后验分析和机理解释等四个相互联系的步骤。研究表明,只有经过综合分析,才能揭示出特征信息的内在规律性,使特征信息具有较好的实用价值。  相似文献   

用红外光谱法研究海泡石的热相变   总被引：3，自引：2，他引：3  

章淑华 《矿物学报》1985,(3)

本文用红外光谱法研究沉积型海泡石粘土岩中海泡石的热稳定性和热相变现象。经实验证实:沉积型海泡石的热稳定上限为375℃,因为在375℃时海泡石的结构开始向滑石型结构变化,一直到800℃为界,呈滑石型结构,从800℃至1200℃则呈顽火辉石结构,在1200℃时还有方英石出现。  相似文献   

Molecular weight distribution,analytical and spectroscopic characterization of humic fractions sequentially isolated by organic solvents from a brown coal humic acid     

Nicola Senesi  Sandor Sipos 《Organic Geochemistry》1985,8(2):157-162

A sequential fractionation procedure employing a series of selected mild organic solvents of different polarity has been applied for the isolation of chemically different organic fractions from a brown coal humic acid. Elemental composition, molecular weight distribution, i.r. and electron spin resonance analysis were carried out on the isolated humic fractions. They were characterized by: (a) a low polydispersity, (b) a decreasing aliphatic and increasing aromatic character along the series, (c) very different molecular weight which significantly correlated with E₄/E₆ ratios (particle aggregation and molecular association) and free radical concentrations (chemical and biochemical activity). Significant correlations were found between physico-chemical parameters of the isolated humic fractions, i.e. M_n, M_w, E₄/E₆ ratios, spins/g contents and the dielectric constants of the solvents used. This suggested the efficiency of the applied procedure in isolating chemically different organic fractions from the bulk, original humic acid.  相似文献   

Importance of the oxidation/maturation pair in the evolution of humic coals     

Landais Patrick  Marc Monthioux  Jean-Dominique Meunier 《Organic Geochemistry》1984,7(3-4)

The natural thermal evolution of type III coals (Humic origin) is expressed during diagenesis by a loss of oxygen as CO₂ and H₂O. Other phenomena such as oxidation can cause extensive geochemical modifications and may complicate the effects of simple maturation.Humic coals from the Jurassic in southeastern Utah were studied by elemental analysis, Rock-Eval pyrolysis and infrared spectroscopy. In a van Krevelen diagram (atomic H/C vs atomic O/C), the samples fall within the envelope defined by 860 reference humic coals covering the entire range of diagenesis. Nevertheless, various criteria (geochemical, petrographic, geological and microscopic) cast doubt upon the interpretation that such a distribution of coal composition results from thermal maturation.The same criteria indicate the intervention of redox phenomena. Comparison of our results with those from artificial and natural oxidation shows that these coals were subjected to an oxidation process different from ordinary late alteration. This process was probably due to circulation of highly oxidizing saline water causing oxygen fixation and the transformation of carboxyls into carboxylate anions. The cations that were fixed are oxygenated and certainly contain calcium, but also uranium and perhaps several other cations (V, Mo, Fe...). Emphasis is placed on possible mechanisms that cause such phenomena.  相似文献   

某些磷灰石矿物的红外吸收光谱   总被引：4，自引：3，他引：4  

彭文世  刘高魁  柯丽琴 《矿物学报》1986,(1)

本文讨论了各种磷灰石矿物的光谱特征,氟磷灰石和羟磷灰石的光谱-结构关系及磷灰石中CO_3~(2-)和OH~(-1)离子的存在形式。在结构资料基础上,对氟磷灰石和羟磷灰石中的PO_4~(3-)离子进行了相关分析,给出了内模式的分配数目。碳氟磷灰石中的CO_3~(2-)离子的光谱与简单无水碳酸盐和氟磷灰石混合物光谱之间的差异表明,C0_3~(2-)离子以类质同象形式进入磷灰石结构中。磷灰石中的P_2O_5含量随CO_2含量的增加而降低,PO_4~(3-)离子的v_4带随CO_2的增加或减少而变化,这表明PO_4~(3-)与CO_3~(2-)离子之间存在密切的相关关系,CO_3~(2-)-PO_4~(3-)取代是类质同象置换的一种形式。羟磷灰石OH-OPO_3中的O-O距离和它的高温光谱证明,OH~(-1)离子以氢键形式存在。  相似文献