基于遗传算法的多光谱影像非监督训练分类系统     

HUNG Chih-Cheng  XIANG Mei  Minh Pham  KUO Bor-Chen  Tommy L. Coleman 《遥感学报》2007,11(5):702-709

本文将遗传算法（GA）应用于非监督训练,提高了遥感数据的分类精度。遗传竞争学习算法（GA-CL）综合了遗传算法和简单的竞争学习算法,可用于改进非监督训练的结果。遗传算法在典型样本聚类的过程中可以避免得到局部最优值。Jeffries-Matusita（J-M）距离法是通过统计测量两个训练类别之间的分离度,可用于评价这种算法。将此算法应用于TM数据的结果显示,遗传算法改进了简单的竞争学习算法,与其他非监督训练算法相比,其提供了K-均值,GA-K-均值和简单的竞争学习算法。  相似文献   

Water environment early warning index system in Tongzhou District     

Xiu-ju Zhang  Ning Qiu  Wen-Rong Zhao  Huan An  Julius Lissa Tommy 《Natural Hazards》2015,75(3):2699-2714

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Tomography of the Earth’s core using supernova neutrinos     

Manfred Lindner  Tommy Ohlsson  Ricard Toms  Walter Winter 《Astroparticle Physics》2003,19(6):755-770

We investigate the possibility to use the neutrinos coming from a future galactic supernova explosion to perform neutrino oscillation tomography of the Earth’s core. We propose to use existing or planned detectors, resulting in an additional payoff. Provided that all of the discussed uncertainties can be reduced as expected, we find that the average matter densities of the Earth’s inner and outer cores could be measured with a precision competitive with geophysics. However, since seismic waves are more sensitive to matter density jumps than average matter densities, neutrino physics would give partly complementary information.  相似文献   

Comment on ‘Z. Şen and A. Altunkaynak,a comparative fuzzy logic approach to runoff coefficient and runoff estimation. Hydrological Processes 20 (2006) 1993–2009’     

Tommy S. W. Wong 《水文研究》2006,20(18):3989-3990

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Multiple band digital orthophoto quadrangle data: A source for generating land use maps     

Tommy L. Coleman 《国际地球制图》2013,28(3):83-90

Abstract

The purpose of this study was to investigate the use of color infrared‐digital orthophoto quadrangle (CIR‐DOQ) data to generate land use/land cover (LULC) maps and to incorporate them as data layers in geographic information systems (GIS) involving various resource management scenarios. The Danville 7.5‐minute quadrangle located in the southern part of Limestone and Morgan counties, Alabama, was used as the study site. Data for the special CIR‐DOQ were generated by scanning four 9x9 inch CIR aerial photographs at a uniform pixel sample grid of 25 microns resulting in 2 meters ground sample resolution. One‐half of the quadrangle was used to identify training sites for performing a supervised classification of the data and the other half to verify the accuracy of the classification. The CIR‐DOQ data were found to be adequate for using a supervised classification algorithm to differentiate major LULC classes, resulting in a classification accuracy of 93 percent. The superior spatial quality of the data over commençai satellite data affords resource managers an opportunity to more effectively study land cover and surface hydrological properties of an area, soil moisture and surface soil textures, as well as differentiate among vegetation species, using remote sensing techniques. However, caution must be exercised when using multispectral classification techniques to classify mosaicked CIRDOQ data because of the image enhancements used to generate the final product. In its present form, there are some limitations to the use of the data for performing spectral classifications. Hozvever, the high spatial resolution of the data enables even the novice resource planner to effectively use the data in visual interpretations of major LULC classes.  相似文献   

Trematode parasites of Otago Harbour (New Zealand) soft‐sediment intertidal ecosystems: Life cycles,ecological roles and DNA barcodes     

Tommy L.F. Leung  Kirsten M. Donald  Devon B. Keeney  Anson V. Koehler  Robert C. Peoples  Robert Poulin 《新西兰海洋与淡水研究杂志》2013,47(4):857-865

Parasites, in particular trematodes (Platyhelminthes: Digenea), play major roles in the population dynamics and community structure of invertebrates on soft‐sediment mudflats. Here, we provide a list of the 20 trematode species currently known to infect molluscs, crustaceans and polychaetes from Otago Harbour (New Zealand) soft‐sediment intertidal areas, as well as information on their transmission modes, life cycles, andknown ecological impacts. Several of the host‐parasite species combinations recorded here are reported for the first time. We also provide DNA barcodes, based on sequences of the cytochrome oxidase subunit l (CO1) gene, for 19 of the 20 trematode species, to facilitate future identification of these parasites in marine ecological studies.  相似文献   

Recent summer precipitation trends in the Greater Horn of Africa and the emerging role of Indian Ocean sea surface temperature   总被引：1，自引：0，他引：1  

A. Park Williams  Chris Funk  Joel Michaelsen  Sara A. Rauscher  Iain Robertson  Tommy H. G. Wils  Marcin Koprowski  Zewdu Eshetu  Neil J. Loader 《Climate Dynamics》2012,39(9-10):2307-2328

We utilize a variety of climate datasets to examine impacts of two mechanisms on precipitation in the Greater Horn of Africa (GHA) during northern-hemisphere summer. First, surface-pressure gradients draw moist air toward the GHA from the tropical Atlantic Ocean and Congo Basin. Variability of the strength of these gradients strongly influences GHA precipitation totals and accounts for important phenomena such as the 1960s–1980s rainfall decline and devastating 1984 drought. Following the 1980s, precipitation variability became increasingly influenced by the southern tropical Indian Ocean (STIO) region. Within this region, increases in sea-surface temperature, evaporation, and precipitation are linked with increased exports of dry mid-tropospheric air from the STIO region toward the GHA. Convergence of dry air above the GHA reduces local convection and precipitation. It also produces a clockwise circulation response near the ground that reduces moisture transports from the Congo Basin. Because precipitation originating in the Congo Basin has a unique isotopic signature, records of moisture transports from the Congo Basin may be preserved in the isotopic composition of annual tree rings in the Ethiopian Highlands. A negative trend in tree-ring oxygen-18 during the past half century suggests a decline in the proportion of precipitation originating from the Congo Basin. This trend may not be part of a natural cycle that will soon rebound because climate models characterize Indian Ocean warming as a principal signature of greenhouse-gas induced climate change. We therefore expect surface warming in the STIO region to continue to negatively impact GHA precipitation during northern-hemisphere summer.  相似文献   

Intelligent modelling of clay compressibility using hybrid meta-heuristic and machine learning algorithms     

Pin Zhang  Zhen-Yu Yin  Yin-Fu Jin  Tommy HTChan  Fu-Ping Gao 《地学前缘(英文版)》2021,12(1):441-452

Compression index Ccis an essential parameter in geotechnical design for which the effectiveness of correlation is still a challenge.This paper suggests a novel modelling approach using machine learning(ML)technique.The performance of five commonly used machine learning(ML)algorithms,i.e.back-propagation neural network(BPNN),extreme learning machine(ELM),support vector machine(SVM),random forest(RF)and evolutionary polynomial regression(EPR)in predicting Cc is comprehensively investigated.A database with a total number of 311 datasets including three input variables,i.e.initial void ratio e0,liquid limit water content wL,plasticity index Ip,and one output variable Cc is first established.Genetic algorithm(GA)is used to optimize the hyper-parameters in five ML algorithms,and the average prediction error for the 10-fold cross-validation(CV)sets is set as thefitness function in the GA for enhancing the robustness of ML models.The results indicate that ML models outperform empirical prediction formulations with lower prediction error.RF yields the lowest error followed by BPNN,ELM,EPR and SVM.If the ranges of input variables in the database are large enough,BPNN and RF models are recommended to predict Cc.Furthermore,if the distribution of input variables is continuous,RF model is the best one.Otherwise,EPR model is recommended if the ranges of input variables are small.The predicted correlations between input and output variables using five ML models show great agreement with the physical explanation.  相似文献   

The distribution and relative toxic potential of organic chemicals in a PCB contaminated bay     

Sundberg H  Tjärnlund U  Kerman G  Blomberg M  Ishaq R  Grunder K  Hammar T  Broman D  Balk L 《Marine pollution bulletin》2005,50(2):195-207

For reliable monitoring of environmental improvement, the PCB contaminated bay Orserumsviken on Sweden's Baltic coast was investigated prior to remediation. We examined PCB congener patterns and the relative toxic potential of PCBs in extracts of three matrices: bottom sediment, settling particulate matter and the dissolved phase (obtained from semi-permeable membrane devices). Congener patterns were similar in all matrices. Three fractions were isolated from the extracts: (1) aliphatic and monocyclic aromatic compounds (MAC-fraction), (2) dicyclic aromatic compounds (DAC-fraction), including PCBs, and (3) polycyclic aromatic compounds (PAC-fraction), including PAHs. Total extracts and fractions were injected into newly fertilised rainbow trout eggs. At larval stage, hepatic EROD activities were quantified. Though high, the PCB contamination could explain only an estimated 1-5% of the total EROD induction. The order of EROD induction potential was: total extract > PAC-fraction > DAC-fraction > MAC-fraction in all matrices, suggesting that in Orserumsviken PACs made a larger contribution to the EROD induction potential than PCBs and other DACs.  相似文献   

Cytochrome P450 in seals: monooxygenase activities, immunochemical cross-reactions and response to phenobarbital treatment     

Anders Goksoyr  Jonny Beyer  Hvard E. Larsen  Tommy Andersson  Lars Frlin 《Marine environmental research》1992,34(1-4)

Cytochrome P450 monooxygenase activities, reflecting the expression of various subfamilies of P450, were measured in liver samples of harp and hooded seal. Differences in some of the investigated parameters were observed between the two species, between sexes, and between pups and adults. Treatment of single female pups from each species with phenobarbital (i.v. 45 mg/kg), resulted in increased levels of EROD and estradiol 2-hydroxylase activities in both species, whereas MCOD, ECOD and PROD activities were induced only in the harp seal sample. Antibodies against a dog P450 2B form (anti-dog PBD-2 IgG) gave a single band around 52kD in both species, strongest in male pups. This band seemed elevated in the PB-treated harp seal pup. Based on the single treated pup of each species, the results suggest that seals respond to PB-type treatment with a weaker response, and with different enzyme patterns, that most terrestrial mammals. Antibodies against cod P450 IAI cross-reacted with two bands in liver samples from adult seals of both species (about 54 and 52kD), but this was strongest in the hooded seal. The intensity of the bands reflected the EROD activities in the samples, suggesting the application of immunodetection in screening marine mammals for effects of environmental contamination.  相似文献