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Land cover mapping using Sentinel-1 SAR and Landsat 8 imageries of Lagos State for 2017

ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH 2020年第1期27卷 66-74页

作者： Makinde, Esther Oluwafunmilayo Oyelade, Edward Oluwasegun Univ York Environm Dept York N Yorkshire England Univ Lagos Fac Engn Dept Surveying & Geoinformat Lagos Nigeria

For several years, Landsat imageries have been used for land cover mapping analysis. However, cloud cover constitutes a major obstacle to land cover classification in coastal tropical regions including Lagos State. In this work, a land cover appearance for Lagos State is examined using Sentinel-1 synthetic aperture radar (SAR) and Land Satellite 8 (Landsat 8) imageries. To this aim, a Sentinel-1 SAR dual-pol (VV+VH) Interferometric Wide swath mode (IW) data orbit for 2017 and a Landsat 8 Operational Land Imager (OLI) for 2017 over Lagos State were acquired and analysed. The Sentinel-1 imagery was calibrated and terrain corrected using a SRTM 3Sec DEM. maximum likelihood classification algorithm was performed. A supervised pixel-based imagery classification to classify the dataset using training points selected from RGB combination of VV and VH polarizations was applied. Accuracy assessment was performed using test data collected from high-resolution imagery of Google Earth to determine the overall classification accuracy and Kappa coefficient. The Landsat 8 was orthorectified and maximum likelihood classification algorithm also performed. The results for Sentinel-1 include an RGB composite of the imagery, classified imagery, with overall accuracy calculated as 0.757, while the kappa value was evaluated to be about 0.719. Also, the Landsat 8 includes a RBG composite of the imagery, classified imagery, but an overall accuracy of 0.908 and a kappa value of 0.876. It is concluded that Sentinel 1 SAR result has been effectively exploited for producing acceptable accurate land cover map of Lagos State with relevant advantages for areas with cloud cover. In addition, the Landsat 8 result reported a high accuracy assessment values with finer visual land cover map appearance.

关键词： Sentinel-1 Landsat 8 Synthetic aperture radar (SAR) imagery Remote sensing maximum likelihood algorithm Land cover Lagos State

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Forest restoration monitoring through digital processing of high resolution images

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ECOLOGICAL ENGINEERING 2019年 127卷 178-186页

作者： Reis, Bruna Paolinelli Martins, Sebastiao Venancio Fernandes Filho, Elpidio Inacio Sarcinelli, Tathiane Santi Gleriani, Jose Marinaldo Leite, Helio Garcia Halassy, Melinda Univ Fed Vicosa Forest Engineer Dept Ave PH Rolfs S-N BR-36570000 Vicosa MG Brazil Univ Fed Vicosa Soil Dept Ave PH Rolfs S-N BR-36570000 Vicosa MG Brazil Fibria Celulose SA Meio Ambiente Florestal Rodovia Aracruz Barra do Riacho S-NKm 25 BR-29197900 Aracruz ES Brazil MTA Ctr Ecol Res Inst Ecol & Bot Alkomany U 2-4 H-2163 Vacratot Hungary Eotvos Lorand Univ Dept Plant Taxon Ecol & Theoret Biol Pazmany P Stny 1-C H-1117 Budapest Hungary

Monitoring and evaluating forest restoration projects is a challenge especially in large-scale, but the remote monitoring of indicators with the use of synoptic, multispectral and multitemporal data allows us to gauge the restoration success with more accurately and in small time. The objective of this study was to elaborate and compare methods of remote monitoring of forest restoration using Light Detection and Ranging (LIDAR) data and multispectral imaging from Unmanned Aerial Vehicle (UAV) camera, in addition to comparing the efficiency of supervised classification algorithms maximum likelihood (ML) and Random Forest (RF). The study was carried out in a restoration area with about 74 ha and five years of implementation, owned by Fibria Celulose S.A., in the southern region of Bahia State, Brazil. We used images from Canon S110 NIR (green, red, Near Infrared) on UAV and LIDAR data composition (intensity image, Digital Surface Model, Digital Terrain Model, normalized Digital Surface Model). The monitored restoration indicator was the land cover separated in three classes: canopy cover, bare soil and grass cover. The images were classified using the ML and RF algorithms. To evaluate the accuracy of the classifications, the Overall Accuracy (OA) and the Kappa index were used, and the last was compared by Z test. The area occupied by different land cover classes was calculated using ArcGIS and R. The results of OA, Kappa and visual evaluation of the images were excellent in all combinations of the imaging methods and algorithms analyzed. When Kappa values for the two algorithms were compared, RF presented better performance than ML with significant difference, but when sensors (UAV camera and LIDAR) were compared, there were no significant differences. There was little difference between the area occupied by each land cover classes generated by UAV and LIDAR images. The highest cover was generated for canopy cover followed by grass cover and bare soil in all classifie

关键词： Light Detection and Ranging (LIDAR) Unmanned Aerial Vehicle (UAV) Random Forest (RF) maximum likelihood algorithm Recovery of degraded areas Forest restoration

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Code timing estimator for DS-CDMA signals in slow fading multipath channels

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ELECTRONICS LETTERS 1999年第19期35卷 1604-1606页

作者： Ye, GT Bi, GA Nanyang Technol Univ Sch Elect & Elect Engn Singapore 2263 Singapore

A maximun likelihood algorithm for code timing estimation of DS-CDMA signals in slow fading multipath channels is presented. As an extension to a recently presented method, it decomposes a multidimensional minimisatio... 详细信息

关键词： maximum likelihood estimation Radiowave propagation multidimensional minimisation problem DS-CDMA signals spread spectrum communication near-far resistant estimator fading channels code timing estimator multipath channels timing code division multiple access maximum likelihood algorithm Multiple access communication slow fading multipath channels

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Ocean surface velocity estimation in multichannel ATI-SAR systems

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ELECTRONICS LETTERS 1998年第25期34卷 2429-2431页

作者： Lombardini, F Griffiths, HD Gini, F Univ London Univ Coll Dept Elect & Elect Engn London WC1E 7JE England Univ Pisa Dept Ingn Informaz I-56126 Pisa Italy

Conventional along-track interferometric (ATI) synthetic aperture radar (SAR) systems derive the ocean surface Velocity from an estimate of the phase difference between the SAR echoes received from two displaced phase centres with a single time-lag. A maximum likelihood algorithm is proposed to process multichannel SAR data from an array of phase centres with multiple time-lags. The new technique provides better estimation accuracy than the conventional technique, unambiguous velocity retrieval, and extended operational capability.

关键词： maximum likelihood estimation ocean surface velocity estimation maximum likelihood algorithm Radar equipment, systems and applications radar imaging along-track interferometric SAR estimation accuracy Probability theory, stochastic processes, and statistics multichannel SAR data phase centres array multiple time-lags multichannel ATI-SAR systems Oceanographic and hydrological techniques and equipment Other topics in statistics Optical, image and video signal processing remote sensing by radar radiowave interferometry Instrumentation and techniques for geophysical, hydrospheric and lower atmosphere research synthetic aperture radar Radar theory oceanographic techniques

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Fractional Brownian motion: Difference iterative forecasting models

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CHAOS SOLITONS & FRACTALS 2019年 123卷 347-355页

作者： Song, Wanqing Li, Ming Li, Yuanyuan Cattani, Carlo Chi, Chi-Hung Shanghai Univ Engn Sci Sch Elect & Elect Engn Shanghai 201620 Peoples R China East China Normal Univ Sch Informat Sci & Technol Shanghai Peoples R China Zhejiang Univ Ocean Coll Hangzhou 316021 Zhejiang Peoples R China Tuscia Univ DEIM Engn Sch Viterbo Italy CSIRO Data 61 Hobart Tas 7015 Australia

Forecasting non-stationary stochastic time series represents a rather complex problem. The reason is that such temporal series are not only self-similar but also exhibit a Long-Range Dependence (LRD). As it is known, the Fractional Brown Motion (FBM) can generate a non-stationary stochastic time series with self-similarity and LRD. In this study we investigate the properties of the LRD for identification of self-similarity and the LRD of non-stationary stochastic series by Hurst exponent. Parameter estimation is proposed for Stochastic differential Equation (SDE) of FBM based on maximum likelihood Estimation (MLE), and proves the convergence of MLE. The SDE is *** difference equation constructed is the prediction model of the iterative format based on FBM. Monte Carlo simulation is applied to check the validity and accuracy of parameter estimation. We also give a practical example to demonstrate the appropriateness of the predictive model. (C) 2019 Published by Elsevier Ltd.

关键词： Fractional Brown motion Long-range dependence Stochastic partial differential equation maximum likelihood algorithm Difference equation

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Harmonic estimation in power systems using an optimised adaptive Kalman filter based on PSO-GA

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IET GENERATION TRANSMISSION & DISTRIBUTION 2019年第17期13卷 3968-3979页

作者： Xi, Yanhui Tang, Xin Li, Zewen Cui, Yonglin Zhao, Ting Zeng, Xiangjun Guo, Jun Duan, Wei Changsha Univ Sci & Technol State Key Lab Disaster Prevent & Reduct Power Gri Changsha 410114 Hunan Peoples R China Natl Univ Def Technol Coll Syst Engineer Changsha 410073 Hunan Peoples R China

A hybrid particle swarm optimisation (PSO) and genetic algorithm (GA) aided Kalman filter (PSO-GA-KF) method for dynamic harmonic state estimation in the power system is investigated. The initial choice of states and KF's parameters, such as process and measurement error covariance matrices significantly affects the estimation precision. Aiming at this problem, a combination of PSO and GA (PSO-GA) is proposed to optimise KF's parameters. In this hybrid algorithm, by replacing the gene mutation operator of GA, the PS algorithm mutation operator is constructed, which can adjust the evolution direction and range based on historical records and swarm records, leading to avoiding the blindness of GA mutation and reducing the probability of devious mutation and enhancing the velocity of evolution. Thus, the global search ability of the hybrid PSO-GA can ensure KF has more accurate estimation of harmonics. To test the effectiveness of the algorithm, several time-varying signals are simulated with harmonics and decaying DC components in the presence of amplitude drift and white noise. Simulation results show that the proposed hybrid algorithm has more accurate estimation, faster convergence and better robustness against noise in comparison with the conventional Kalman filter (KF), KF based on the maximum likelihood and PSO aided KF (PSO-KF).

关键词： genetic algorithms particle swarm optimisation power system state estimation adaptive Kalman filters power system harmonics harmonic analysis estimation theory probability power harmonic filters genetic algorithm dynamic harmonic state estimation measurement error covariance matrices gene mutation operator PS algorithm mutation operator time-varying power system signals hybrid PSO-GA mutation optimised adaptive Kalman filter parameters PSO-GA-KF parameters probability global search ability maximum likelihood algorithm

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SPATIAL-TEMPORAL DETECTION OF ELECTROOPTIC MOVING TARGETS

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IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS 1995年第2期31卷 608-616页

作者： POHLIG, SC Lincoln Laboratory Massachusetts Institute of Technology Lexington MA USA

A maximum likelihood algorithm to detect moving targets in space-time electro-optic data is derived using a model of temporally stationary and spatially nonstationary clutter statistics. Performance is evaluated in terms of the probabilities of false alarm and detection. This algorithm is applied to a variety of image sequences: visible band and infrared (IR) sensors, with terrestrial and celestial clutter backgrounds. Comparison of theoretically predicted and experimentally derived statistics shows excellent agreement, validating the model and theoretical predictions.

关键词： clutter infrared detectors maximum likelihood detection motion estimation target tracking celestial clutter backgrounds electro-optic moving targets image sequences infrared sensors maximum likelihood algorithm moving targets probabilities space-time ele

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Efficiency of Optimal Joint Detection and Estimation of Image Areas with Spatial Noise

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OPTOELECTRONICS INSTRUMENTATION AND DATA PROCESSING 2013年第3期49卷 221-227页

作者： Trifonov, A. P. Zimovets, K. A. Korchagin, Yu. E. Voronezh State Univ Univ Pl 1 Voronezh 394006 Russia

Bayesian and maximum likelihood algorithms are considered. A comparative analysis of their effectiveness is performed. The results are specified for an image in the shape of an ellipse with linearly varying intensity.

关键词： maximum likelihood algorithm Bayesian algorithm characteristics of algorithms statistical modeling

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Exploring 16 years changing dynamics for land use/land cover in Pearl City (Thoothukudi) with spatial technology

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SPATIAL INFORMATION RESEARCH 2017年第4期25卷 547-554页

作者： David, T. Immanuvel Mukesh, M. V. Kumaravel, S. Ramesh, G. Premkumar, R. Annamalai Univ Dept Earth Sci Chidambaram Tamil Nadu India

Land use land cover (LU/LC) changes over the period are essential to understand the development of human activities within a region to define the impact of anthropogenic and natural activities. The virtual assessment of LU/LC changes between 2000 and 2016 is carried out in Pearl City (Thoothukudi) using Remote-Sensing data and GIS tool. This change detection is done by 15 m resolution cloud-free Advanced Spaceborne Thermal Emission and Reflection Radiometer data captured during the year 2000 and 2016. The dynamic changes depict the major land use features like settlements, saltpan, crop land, vegetation, barren and water body from satellite data through supervised classifications of a maximum likelihood algorithm. The classified images highlight a series of constructive results in settlement (4.30%), vegetation (4.00%), saltpan (0.24%) and pessimistic results in barren land (-7.68%), crop land (-0.64%) and water body (-0.23%) respectively. The study recommends that urbanization of settlement land usage is highly mobilized in Thoothukudi coastal areas.

关键词： Changing dynamics Land use/land cover (LU/LC) Pearl City maximum likelihood algorithm

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Estimation of the resting motor threshold (RMT) in transcranial magnetic stimulation using relative-frequency and threshold-hunting methods in brain tumor patients

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ACTA NEUROCHIRURGICA 2019年第9期161卷 1845-1851页

作者： Engelhardt, Melina Schneider, Heike Gast, Theresa Picht, Thomas Charite Dept Neurosurg Charitepl 1 D-10117 Berlin Germany Charite Einstein Ctr Neurosci Charitepl 1 D-10117 Berlin Germany Charite Int Grad Program Med Neurosci Charitepl 1 D-10117 Berlin Germany

Background Application of transcranial magnetic stimulation is often based on the resting motor threshold. The aim of this study was to validate recent findings on the advantage of resting motor threshold estimation using adaptive threshold-hunting algorithms over the Rossini-Rothwell method in a clinical sample and healthy subjects. Methods Resting motor thresholds in 115 patients with a brain tumor and 10 healthy subjects were assessed using the Rossini-Rothwell method and compared to an adaptive threshold-hunting algorithm. In healthy subjects, this measurement was repeated twice to capture test-retest reliability of both methods. Efficiency of both methods was assessed by comparing the number of pulses needed for resting motor threshold estimation. Results There was no significant difference between the Rossini-Rothwell method and the adaptive threshold-hunting algorithm in patients and healthy controls with limits of agreement between +/- 12 V/m. There was a strong intraclass correlation and both methods showed a good test-retest reliability. However, the adaptive threshold-hunting algorithm was significantly faster. Conclusions The adaptive threshold-hunting algorithm was more efficient in assessing the resting motor threshold, while reaching comparable results as the Rossini-Rothwell method. Thus, our results support the advantage of adaptive threshold-hunting algorithms to determine the resting motor threshold also in a clinical sample.

关键词： Transcranial magnetic stimulation (TMS) Resting motor threshold (RMT) Rossini-Rothwell method Adaptive threshold-hunting maximum likelihood algorithm

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