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1.
本研究将地物高光谱遥感技术应用于室内实验,从而得到小球藻和铜绿微囊藻的高光谱特征.通过多种半经验方法,如单波段、波段比值和微分法,建立了两藻种最优的Chl-a高光谱定量模型,并与室外情况进行了对比.结果表明:小球藻的最优定量模型为Chl-a=174.6 1138292(R703) 2.3(109[(R703)]2(p＜0.01),相应的方法适宜性为:一阶微分法＞单波段法＞波段比值法;铜绿微囊藻的最优定量模型为Chl-a=5299164(R757)1.9773(p＜0.01),相应的方法适宜性为:单波段法＞波段比值法＞一阶微分法;从高光谱特征来看,小球藻在540 nm和700 nm附近存在明显的特征波峰,其位置随Chl-a浓度增大而向长波方向偏离,铜绿微囊藻在530 nm、660 nm和700 nm附近存在3个较强的特征波峰,在610 nm和680 nm附近存在明显的波谷;与以往室外研究不同的是铜绿微囊藻的反射率在400-500 nm之间的R值并不低,是因为没有非藻类颗粒物的影响,总吸收明显降低. 相似文献
2.
Estimating field‐saturated soil hydraulic conductivity by a simplified Beerkan infiltration experiment 
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下载免费PDF全文 Field‐saturated soil hydraulic conductivity, Kfs, is highly variable. Therefore, interpreting and simulating hydrological processes, such as rainfall excess generation, need a large number of Kfs data even at the plot scale. Simple and reasonably rapid experiments should be carried out in the field. In this investigation, a simple infiltration experiment with a ring inserted shortly into the soil and the estimation of the so‐called α* parameter allowed to obtain an approximate measurement of Kfs. The theoretical approach was tested with reference to 149 sampling points established on Burundian soils. The estimated Kfs with the value of first approximation of α* for most agricultural field soils (α* = 0.012 mm?1) differed by a practically negligible maximum factor of two from the saturated conductivity obtained by the complete Beerkan Estimation of Soil Transfer parameters (BEST) procedure for soil hydraulic characterization. The measured infiltration curve contained the necessary information to obtain a site‐specific prediction of α*. The empirically derived α* relationship gave similar results for Kfs (mean = 0.085 mm s?1; coefficient of variation (CV) = 71%) to those obtained with BEST (mean = 0.086 mm s?1; CV = 67%), and it was also successfully tested with reference to a few Sicilian sampling points, since it yielded a mean and a CV of Kfs (0.0094 mm s?1 and 102%, respectively) close to the values obtained with BEST (mean = 0.0092 mm s?1; CV = 113%). The developed method appears attractive due to the extreme simplicity of the experiment. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
3.
The effect of mature compost (MC) used as a bulking agent on ammonia, hydrogen sulfide, and short‐chain fatty acids emission reduction during sewage sludge (SS) composting process was studied in this paper. Three types of mixtures, single SS, SS + wood chips (SS + WC), and SS + MC, were composted in a laboratory reactor. Among the different treatments, decrement rates of NH3 emission (based on initial TN) from SS to SS + MC and SS + WC to SS + MC were 63 and 59%, respectively. The H2S concentration ranged from 0.759 to 1.140 mg m?3 for SS, from 0.075 to 0.455 mg m?3 for SS + WC, and from 0.075 to 0.425 mg m?3 for SS + MC and the short‐chain fatty acids (C2–C5) concentration ranged from 0.10 to 1.00 ppm for SS, from 0.10 to 1.50 ppm for SS + WC, and from 0.10 to 0.80 ppm for SS + MC. In addition, the temperature apparently, as well as the thermophilic stage, was also elevated by bulking agent addition, especially by the MC addition. The denaturing gradient gel electrophoresis analysis indicated that there was more diversity of the bacterial community during the SS + MC process. According to these results, MC was a suitable bulking agent for reduction ammonia, hydrogen sulfide, and short‐chain fatty acids emission during the SS composting. 相似文献
4.
This study develops a straightforward approximate method to estimate inelastic displacement ratio, C1 for base‐isolated structures subjected to near‐fault and far‐fault ground motions. Taking into account the inelastic behavior of isolator and superstructure, a 2 degrees of freedom model is employed. A total of 90 earthquake ground motions are selected and classified into different clusters according to the frequency content features of records represented by the peak ground acceleration to peak ground velocity ratio, Ap/Vp. A parametric study is conducted, and effective factors in C1 (i.e., fundamental vibration period of the superstructure, Ts; postyield stiffness ratio of the superstructure, αs; strength reduction ratio, R; vibration period of the isolator, Tb; strength of the isolator, Q; ratio of superstructure mass to total mass of the system, γm) are recognized. The results indicate that the practical range of C1 values could be expected for base‐isolated structures. Subsequently, effective parameters are included in simple predictive equations. Finally, the accuracy of the proposed approximate equations is evaluated and verified through error measurement, and comparisons are made in the analyses. 相似文献
5.
《水文科学杂志》2013,58(3)
Abstract Remote sensing technology is being conceived as a cost-effective tool to monitor the eutrophication problem in shallow inland lakes and reservoirs. The objective of this study is to develop hyperspectral remote sensing algorithms for chlorophyll and accessory pigments retrieval in the Ishizuchi Reservoir in Japan. The laboratory reflectance data of 207 field samples with manipulated pigment and suspended sediment concentrations were measured between 400 and 700 nm with a hyperspectral spectroradiometer, and integrated into 60 contiguous narrow bands. Band ratio and spectral absorption algorithms were developed by regression analysis with the observed chlorophyll measurements, and their estimation accuracies were evaluated using the RMSE of the estimates. Algorithms developed from spectral absorption ratios a(675 nm)/a*(675 nm) for five different classes of total pigment concentrations were more accurate than the algorithms based on band ratios Rrs (538 nm)/Rrs (488 nm), Rrs (581 nm)/Rrs (463 nm) and Rrs (674 nm)/Rrs (622 nm) as a result of removing the influence of overlapping absorption and scattering by water molecules and suspended solids from total absorption spectra. 相似文献
6.
Evaporation modelling by heuristic regression approaches using only temperature data 总被引：1，自引：1，他引：0
Accurate estimation of pan evaporation (Epan) is very important in water resources management, irrigation scheduling and water budget of lakes. This study investigates the accuracy of two heuristic regression approaches, multivariate adaptive regression splines (MARS) and M5 model tree (M5Tree) in estimating pan evaporation using only temperature data as input. Monthly minimum temperature, maximum temperature and Epan data from three Turkish stations were used, with month number (periodicity information) added as input to see its effect on estimation accuracy. The models were compared with the calibrated Hargreaves-Samani (CHS), Stephens-Stewart (SS) and multiple linear regression methods. Three different train-test splitting strategies (50%–50%, 60%–40% and 75%–25%) were employed for better evaluation of the applied methods. The results show that the MARS method generally estimated monthly Epan with higher accuracy compared to the M5Tree, CHS and SS methods. When extraterrestrial radiation, calculated from Julian date and latitude information, was used as input to the SS instead of solar radiation, satisfactory estimates were obtained. A positive effect on model accuracy was observed when involving periodicity information in inputs and increasing training data length. 相似文献
7.
Seismic reflection methods are being developed at the University of Manitoba to aid in determining fine crustal structure in the Precambrian of Manitoba and northwestern Ontario. Present-day environmental concern as well as mineshaft conditions necessitate the detonation of several smaller charges repeated, say, I times and followed by ‘vertical’ stacking. To obtain the familiar √I improvement in signal-to-noise (S:N) amplitude ratio applying the straight-sum (SS) method, one assumes, among other things, that both S:N ratio and signal variance are the same on all traces. Dropping these assumptions, as we must for our data, it becomes necessary to apply weighting coefficients to optimize the S:N ratio of the stacked trace. We still assume the signal shapes to be the same for repeated shots, so for the jth trace on the record of the ith shot we model the time series as: tij=ai (sj+nij); where ai is a scaling factor. The proper weights wi are then shown to be proportional to σsi/σ2ni where σ2 is variance, or to γi/ai where γi is S:N power ratio. Applying the weighted-stack (WS) method gives S:N amplitude ratios which are, on average, 55% of the optimal ratios expected from WS theory compared with only 24% for the SS method. The 45% shortfall in WS performance is ascribed mainly to trace-alignment (or time-delay) errors. Varying noise levels on individual traces, slight dissimilarity of signal shape, and correlated noise may also contribute to a lesser extent (in decreasing order of significance). This WS method appears to strike a good practical balance between S:N improvement and processing efficiency. 相似文献
8.
Biodegradation of polycyclic aromatic hydrocarbons (PAHs) in contaminated sediment is an attractive remediation technique and its success depends on biodegradation kinetics, and the optimal condition for the PAH-degrading isolates; however, information on this aspect is still scarce. The effects of multi-factors on biodegradation of phenanthrene, a 3-ring model PAH, in contaminated sediment slurry by Sphingomonas sp. a bacterial strain isolated from surface mangrove sediment, were investigated using the orthogonal experimental design (form L16(45)). The most significant factors were salinity and inoculum size, while the effects of phenanthrene concentrations, nutrient addition and temperatures were insignificant. The optimal biodegradation condition in contaminated mangrove sediment slurry was 30 °C, 15 ppt salinity, a carbon/nitrogen ratio of 100:1 (the background ratio in sediment) and an inoculum size of 106 most probable number g−1 sediment. The phenanthrene biodegradation could be best described by the first order rate model, C = C0e−kt, where k (the rate constant) is equaled to 0.1185, under the optimal condition. The kinetic model was verified and its validity in predicting biodegradation by Sphingomonas sp. at various phenanthrene concentrations was proved by experimental data. 相似文献
9.
官厅水库秋季悬浮颗粒物和CDOM吸收特性 总被引：2，自引：0，他引：2
利用2012年9月5日在官厅水库采集的水体吸收系数数据,对总悬浮颗粒物、浮游植物色素颗粒物、非色素颗粒物和有色可溶性有机物的吸收特性进行研究.结果表明:秋季官厅水库的颗粒物吸收以浮游植物色素吸收为主,总颗粒物吸收光谱与浮游藻类吸收光谱相似;非色素颗粒物和有色可溶性有机物的吸收系数随波长的增大接近指数规律衰减;ad(440)、ad(675)与CChl.a呈显著相关,表明官厅水库秋季的非色素颗粒物主要来源于浮游藻类降解产物,陆源性输入较少;a ph(440)、a ph(675)与CChl.a存在显著线性关系,但其比吸收系数较为恒定,与CChl.a基本无关;不同采样点的不同组分吸收系数对总吸收系数的贡献不同,大致有4种表现类型.在富营养程度较高的妫库区,浮游植物色素是水体光谱吸收的主导因子;在富营养程度较低的中库区,颗粒物与有色可溶性有机物共同主导水体光谱吸收. 相似文献
10.
Fluctuations of the refractive index associated with atmospheric turbulence affect the propagation of electromagnetic and acoustic waves in the atmosphere. In the reported study, the effects of turbulence on wave propagation in the atmospheric convective boundary layer (CBL) are considered in terms of the second-order refractive index structure function and related to its structure-function parameter C n 2. Two structure-function evaluation methods are compared. The direct evaluation method involves calculating the refractive index at each point in the simulation domain with subsequent calculation of the structure function. The second method is based on a parameterized linear relationship between the refractive-index structure function and temperature/humidity structure functions. For each evaluation method, vertical profiles of C n 2 computed for separations along the three coordinate directions collapse together over a significant portion of the CBL. Near-surface divergence of C n 2 values along the horizontal directions was noted and attributed to the influence of surface wind shear on the turbulent fluctuations of temperature and humidity. The behavior of C n 2 near the surface was shown to agree favorably with similarity-theory predictions. 相似文献
11.
An igneous intrusion of 94m thick was discovered intruding into the Silurian sandstone from Tazhong 18 Well. The petroleum
previously preserved in the Silurian sandstone reservoir was altered into black carbonaceous bitumen by abnormally high heat
stress induced by the igneous intrusion. The reflectance of the carbonaceous bitumen reaches as high as 3.54%, indicating
that the bitumen had evolved into a high thermal evolution level. Similar to the Silurian samples from the neighboring Tazhong
11, Tazhong 12, Tazhong 45 and Tazhong 47 wells, the distribution of C27, C28 and C29 steranes of the carbonaceous bitumen is still “V”-shaped and can still be employed as an efficient parameter in oil source
correlation. The “V”-shaped distribution indicates that the hydrocarbons from the Tazhong 18 and the neighboring wells were
all generated from the Middle-Upper Ordovician hydrocarbon source rocks. However, the oil source correlation parameters associated
with and terpanes had been changed greatly by the high heat stress and can no longer be used in oil source correlation. The
δ
13C values of the petroleum from the neighboring wells are between −32.53%. and −33.37%., coincident with those of the Paleozoic
marine petroleum in the Tarim Basin. However, the δ
13C values of the carbonaceous bitumen from the Tazhong 18 Well are between −27.18%. and −29.26%., isotopically much heavier
than the petroleum from the neighboring wells. The content of light hydrocarbons (nC14−nC20) of the saturated hydrocarbon fraction in the carbonaceous bitumen is extremely higher than the content of heavy hydrocarbons.
The light/heavy hydrocarbon ratios (ΣnC21
−/ΣnC22
+ are between 4.56 and 39.17. In the saturated fraction, the even numbered hydrocarbons are predominant to the odd numbered,
and the OEP (Odd to Even Predominance) values are between 0.22 and 0.49. However, the content of light hydrocarbons in the
petroleum from the neighboring wells is relatively low and the content of the even numbered hydrocarbons is almost equal to
that of the odd numbered. Compared with the samples from the neighboring wells, the abundance of non-alkylated aromatic hydrocarbons,
such as phenanthrenes, and polycyclic aromatic hydrocarbons (PAHs), such as fluoranthane, pyrene, benzo[a]anthracene and benzofluoranthene,
are relatively high.
Supported by the National Key Basic Research and Development Project (Grant No. 2005CB422103) 相似文献
12.
The monthly means of north component X of geomagnetic field from 16 observatories during 1984–1988 were analyzed using the
Sompi spectral analysis technique Most of these observatories are located in China. The analysis of the semiannual variations
indicates that the latitude has no apparent effect on the X component. This clearly implies that the source field mode of
semiannual variations cannot simply be described by using the p
1
0
mode. Using the p
1
0
mode to estimate the inductive scale lengthC in the semiannual period, the value ofC at each observatory would be biased significantly. The purpose of this study is to find which kind of modes is optimal for
estimating the values ofC corresponding to the semiannual variations. The results show that a composite mode, involving five terms P
n
0
(n = 1,, 5), might be a reasonable and acceptable one 相似文献
13.
XIONG Yongqiang GENG Ansong WANG Yunpeng LIU Dehan JIA Rongfen SHEN Jiagui XIAO Xianming 《中国科学D辑(英文版)》2002,45(1):13-20
The kinetic parameters of generation have been obtained for different hydrocarbon classes, including methane, C2-C5 gas hydrocarbons, C6-C13 light hydrocarbons and C13+ heavy hydrocarbons, and vitrinite reflectance (R°) by the kinetic simulating experiment of kerogen cracking. Then, combined with the detailed geology of Sichuan Basin, the
effective gas-generating intensity of the Lower Cambrian source rock is approximately estimated by applying these parameters. 相似文献
14.
Djim M. L. Diongue Christine Stumpp Olivier Roupsard Didier Orange Frederic C. Do Serigne Faye 《水文研究》2023,37(1):e14787
Sustainable water management in semi-arid agriculture practices requires quantitative knowledge of water fluxes within the soil-vegetation-atmosphere system. Therefore, we used stable-isotope approaches to evaluate evaporation (Ea), transpiration (Ta), and groundwater recharge (R) at sites in Senegal's Groundnut basin and Ferlo Valley pasture region during the pre-monsoon, monsoon, and post-monsoon seasons of 2021. The approaches were based upon (i) the isothermal evaporation model (for quantifying Ea); (ii) water and isotope mass balances (to partition Ea and Ta for groundnut and pasture); and (iii) the piston displacement method (for estimating R). Ea losses derived from the isothermal evaporation model corresponded primarily to Stage II evaporation, and ranged from 0.02 to 0.09 mm d−1 in the Groundnut basin, versus 0.02–0.11 mm d−1 in Ferlo. At the groundnut site, Ea rates ranged from 0.01 to 0.69 mm d−1; Ta was in the range 0.55–2.29 mm d−1; and the Ta/ETa ratio was 74%–90%. At the pasture site, the ranges were 0.02–0.39 mm d−1 for Ea; 0.9–1.69 mm d−1 for Ta; and 62–90% for Ta/ETa. The ETa value derived for the groundnut site via the isotope approach was similar to those from eddy covariance measurements, and also to the results from the previous validated HYDRUS-1D model. However, the HYDRUS-1D model gave a lower Ta/ETa ratio (23.2%). The computed groundwater recharge for the groundnut site amounted to less than 2% of the local annual precipitation. Recommendations are made regarding protocols for preventing changes to isotopic compositions of water in samples that are collected in remote arid regions, but must be analysed days later. The article ends with suggestions for studies to follow up on evidence that local aquifers are being recharged via preferential pathways. 相似文献
15.
DAI JinXing NI YunYan HU GuoYi HUANG ShiPeng LIAO FengRong YU Cong GONG DeYu WU Wei 《中国科学:地球科学(英文版)》2014,57(1):88-103
By the end of the year 2010,a total of 15 large tight gas fields have been found in China,located in the Ordos,Sichuan,and Tarim basins.The annual production and total reserves of these fields in 2010 were 222.5×108and 28657×108m3,respectively,accounting for 23.5%and 37.3%,respectively,of the total annual production and reserves of natural gases in China.They took a major part of all natural gas production and reserves in China.According to the analyses of 81 gas samples,the stable carbon and hydrogen isotopic compositions of tight gases in China have following characteristics:(1)Plots of 13C1-13C2-13C3,13C1-C1/C2+3and 13C1-13C2demonstrate the coal-derived origin of tight gases in China;(2)For the primary alkane gases,both carbon and hydrogen isotopic values increase with increasing molecular mass,i.e.,13C113C213C313C4and2H12H22H3;(3)The isotopic differences of 13C2-13C1,13C3-13C1,2H2-2H1and 2H3-2H1decrease with increasing Ro(%)and C1/C1–4;(4)There are seven causes for the carbon and hydrogen isotopic reversal,however,the carbon and hydrogen isotopic reversal of tight gases in China is caused mainly by multiple stages of gas charge and accumulation. 相似文献
16.
We have developed a thermodynamic model for the determination of the closure temperature (TC) at which the minerals defining an internal isochron in RbSr, or similar, geochronological system were set with a geochronological clock. It is shown that the equilibrium fractionation of87Rb and87Sr between a pair of minerals at TC [KD(87Rb87Sr)C] is given by the ratio of the quantity (87Rb/86Sr) in the two minerals as measured at the present time. KD(87Rb-87Sr), which equals the element distribution coefficient KD(RbSr) under equilibrium condition, can be calibrated as a function of temperature, and compared with the retrieved value of KD(87Rb87Sr)C in a natural pair to obtain TC. The various mineral pairs defining an internal isochron will yield concordant or discordant values of TC depending on whether or not they closed simultaneously with respect to the diffusion of Rb and Sr. Both types of results are expected, and are important in the analyses of the evolutionary history of the host rocks. Preliminary analyses of the published data in the RbSr system suggest a fairly wide range of TC even for the same mineral pair, reflecting differences in the cooling rates and physico-chemical environments of the host rocks. 相似文献
17.
《国际泥沙研究》2023,38(4):556-565
The new concept presented for forecasting the rate of accumulation of suspended sediment in reservoir water in the bottom sediment allows reasonable estimates of the siltation process globally, regionally, or locally, to be obtained without the need for costly research. The method draws on three key parameters, i.e., the concentration of suspended sediments (SS), and its organic matter (OMSS) content, as well as the storage capacity (VR) (i.e., the water storage in the reservoir). All of these parameters easy to determine, with information on them, in fact, made widely available by most agencies managing reservoirs in different parts of the world. In practice, the proposed method can represent a missing link in the precise determination of a reservoirs rate of siltation (and hence, losses of storage capacity). 相似文献
18.
Inversion of gravity and magnetic anomalies over some bodies of simple geometric shape 总被引：1，自引：0，他引：1
The general expression for gravity and magnetic anomalies over thin sheets and sloping contacts may be expressed as a polynomial of the formFx
2+C1Fx+C2F+C3x3+C4x2+C5x+C6. The initial parameters of the source are obtained from the coefficientsC
1, C2,..., C6 which may be solved by inverting a 6×6 matrix. The initial parameters are modified by successive iteration process using the difference formula until the root mean square error between the observed and calculated anomalies is a minimum. The regional background which may be in the form of a polynomial is estimated by the computer itself. This method is applied on a number of field anomalies and is found to yield reliable estimates of depth and other parameters of the source. 相似文献
19.
结合高光谱数据反演吉林石头口门水库悬浮物含量和透明度 总被引：6，自引：1，他引：5
水中悬浮物含量是评价水环境质量的一个重要参数,它可影响水体透明度、混浊度、水色等光学性质,决定太阳光照在水下的分布和浮游植物对光照的利用,并最终影响水体的初级生产力.本文利用长春市石头口门水库的高光谱实测数据和水质采样分析数据,尝试通过一阶微分法建立悬浮物估测模型,再用估测结果反演透明度信息.结果表明:用590nm处的一阶微分光谱值建立的悬浮物估测模型的决定系数R2和均方根误差(RMSE)分别为0.76、9.09 mg/L,验证模型的R2和RMSE分别为0.79、7.15 mg/L;石头口门水库上游严重的水土流失导致透明度受悬浮物含量影响较大,两者存在明显的指数关系,相关系数r为-0.80,用悬浮物含量建立的透明度估测模型的R2和RMSE分别为0.79和0.12 m,验证模型的R2和RMSE分别为0.82、0.11 m.显著水平均为p＜0.01.研究结果表明,该方法用于石头口门水库悬浮物含量和透明度的定量遥感结果较理想. 相似文献
20.
Identification of robust hyperspectral indices on forest leaf water content using PROSPECT simulated dataset and field reflectance measurements 总被引：1，自引：0，他引：1
In this study, we aim at finding efficient and robust hyperspectral indices for estimating forest leaf water content parameters (equivalent water thickness, EWT and fuel moisture content, FMC), which are useful for the understanding of terrestrial ecosystem functioning and evaluating fire risk. The most efficient hyperspectral indices have been identified (both on the context of index types and wavelength domains) using both a simulated dataset generated from the calibrated leaf reflectance model, PROSPECT, and datasets of field measured reflectance. Results indicate that high precision can be obtained using the type of vegetation index of two wavelength bands based on reflectance derivatives to estimate both parameters, with overall R2 and RMSE of 0·60 ～ 0·75 and 0·0009 ～ 0·0012 g cm?2 for EWT, 0·63 ～ 0·87 and 0·12 ～ 0·20 g g?1 for FMC, respectively. The best indices identified in this study for vegetation water status in temperate deciduous forests were dSR (1510, 1560) for EWT and dSR (2110, 2260) for FMC, with widths of wavebands (Δλ) be variable up to 50 nm for both dSR indices. Despite the obvious discrepancies found in fit when applying the identified indices to different datasets, the indices identified in this study are applicable to various species (Dataset III), various phenological stages, different sites (Dataset I) and various leaf anatomies (Dataset II), and therefore suitable for an all inclusive wide range of application especially in temperate deciduous forests. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献