Crop classification using biologically-inspired techniques with high resolution satellite image   总被引：5，自引：0，他引：5  

S. N. Omkar  J. Senthilnath  Dheevatsa Mudigere  M. Manoj Kumar 《Journal of the Indian Society of Remote Sensing》2008,36(2):175-182

Remote sensing provides a lucid and effective means for crop coverage identification. Crop coverage identification is a very important technique, as it provides vital information on the type and extent of crop cultivated in a particular area. This information has immense potential in the planning for further cultivation activities and for optimal usage of the available fertile land. As the frontiers of space technology advance, the knowledge derived from the satellite data has also grown in sophistication. Further, image classification forms the core of the solution to the crop coverage identification problem. No single classifier can prove to satisfactorily classify all the basic crop cover mapping problems of a cultivated region. We present in this paper the experimental results of multiple classification techniques for the problem of crop cover mapping of a cultivated region. A detailed comparison of the algorithms inspired by social behaviour of insects and conventional statistical method for crop classification is presented in this paper. These include the Maximum Likelihood Classifier (MLC), Particle Swarm Optimisation (PSO) and Ant Colony Optimisation (ACO) techniques. The high resolution satellite image has been used for the experiments.  相似文献   

Maintaining real-time precise point positioning during outages of orbit and clock corrections   总被引：1，自引：1，他引：0  

Ahmed El-Mowafy  Manoj Deo  Nobuaki Kubo 《GPS Solutions》2017,21(3):937-947

The precise point positioning (PPP) is a popular positioning technique that is dependent on the use of precise orbits and clock corrections. One serious problem for real-time PPP applications such as natural hazard early warning systems and hydrographic surveying is when a sudden communication break takes place resulting in a discontinuity in receiving these orbit and clock corrections for a period that may extend from a few minutes to hours. A method is presented to maintain real-time PPP with 3D accuracy less than a decimeter when such a break takes place. We focus on the open-access International GNSS Service (IGS) real-time service (RTS) products and propose predicting the precise orbit and clock corrections as time series. For a short corrections outage of a few minutes, we predict the IGS-RTS orbits using a high-order polynomial, and for longer outages up to 3 h, the most recent IGS ultra-rapid orbits are used. The IGS-RTS clock corrections are predicted using a second-order polynomial and sinusoidal terms. The model parameters are estimated sequentially using a sliding time window such that they are available when needed. The prediction model of the clock correction is built based on the analysis of their properties, including their temporal behavior and stability. Evaluation of the proposed method in static and kinematic testing shows that positioning precision of less than 10 cm can be maintained for up to 2 h after the break. When PPP re-initialization is needed during the break, the solution convergence time increases; however, positioning precision remains less than a decimeter after convergence.  相似文献   

Numerical Study of Mine Site Specific Multiseam Mining and Its Impact on Surface Subsidence and Chain Pillar Stress     

Manoj Khanal  Deepak Adhikary  Chandana Jayasundara  Rao Balusu 《Geotechnical and Geological Engineering》2016,34(1):217-235

This paper investigates various multiseam mining related parameters using mine site specific data and numerical simulations. Two important mining effects—subsidence and stress—are analysed for different possible mining layouts. A geological mine dataset has been used to generate a numerical model. The predicted surface subsidence magnitude and surface profile have been compared under different scenarios to assess potential options in multiseam mining strategies. The effects that seam separation distances, mining offset, panel layout and panel orientation each have on surface subsidence and chain pillar stress magnitude have been investigated. The numerical simulation shows that ascending or descending mining directions have little impact on controlling the surface subsidence in multiseam mining and predicted an almost identical maximum stress development at the chain pillars. Numerical simulations infer that the orientation of the top panels control the subsidence profile.  相似文献   

Development of Web Based Road Accident Data Management System in GIS Environment: a Case Study     

Ashish Dhamaniya  Mathew Sonu  M. Krishnanunni  Pynam Praveen  Austin Jaijin 《Journal of the Indian Society of Remote Sensing》2016,44(5):789-796

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Gravity anomalies and deep structure of the Ninetyeast Ridge north of the equator,eastern Indian Ocean — a hot spot trace model     

Manoj Mukhopadhyay  M. B. R. Krishna 《Marine Geophysical Researches》1995,17(2):201-216

The Ninetyeast Ridge north of the equator in the eastern Indian Ocean is actively deforming as evidenced by seismicity and its eastward subduction below the Andaman Trench. Basement of the ridge is elevated nearly 2 km with respect to the Bengal Fan; seismic surveys demonstrate continuity of the ridge beneath sediment for 700 km north of 10° N where the ridge plunges below the Fan sediment. The ridge is characterised by a free-air gravity high of 50 mgal amplitude and 350 km wavelength, and along-strike continuity of 1500 km in a north-south direction, closely fringing (locally, even abutting) the Andaman arc-trench bipolar gravity field. Regression analysis between gravity and bathymetry indicates that the ridge gravity field cannot be explained solely by its elevation. The ridge gravity field becomes gradually subdued northwards where overlying Bengal Fan sediments have a smaller density contrast with the ridge material. Our gravity interpretation, partly constrained by seismic data, infers that the ridge overlies significant crustal mass anomalies consistent with the hot spot model for the ridge. The anomalous mass is less dense by about 0.27 g cm^–3 than the surrounding oceanic upper mantle, and acts as a cushion for isostatic compensation of the ridge at the base of the crust. This cushion is up to 8 km thick and 400–600 km wide. Additional complexities are created by partial subduction of the ridge below the Andaman Trench that locally modifies the arc-trench gravity field.  相似文献   

A Computationally Efficient,Time-Dependent Model of the Solar Wind for Use as a Surrogate to Three-Dimensional Numerical Magnetohydrodynamic Simulations     

Owens  Mathew  Lang  Matthew  Barnard  Luke  Riley  Pete  Ben-Nun  Michal  Scott  Chris J.  Lockwood  Mike  Reiss  Martin A.  Arge  Charles N.  Gonzi  Siegfried 《Solar physics》2020,295(3):1-15

Solar radiation variability spans a wide range in time, ranging from seconds to decadal and longer. The nearly 40 years of measurements of solar irradiance from space established that the total solar irradiance varies by \(\approx 0.1\%\) in phase with the Sun’s magnetic cycle. Specific intervals of the solar spectrum, e.g., ultraviolet (UV), vary by orders of magnitude more. These variations can affect the Earth’s climate in a complex non-linear way. Specifically, some of the processes of interaction between solar UV radiation and the Earth’s atmosphere involve threshold processes and do not require a detailed reconstruction of the solar spectrum. For this reason a spectral UV index based on the (FUV-MUV) color has been recently introduced. This color is calculated using SORCE SOLSTICE integrated fluxes in the FUV and MUV bands. We present in this work the reconstructions of the solar (FUV-MUV) color and Ca ii K and Mg ii indices, from 1749–2015, using a semi-empirical approach based on the reconstruction of the area coverage of different solar magnetic features, i.e., sunspot, faculae and network. We remark that our results are in noteworthy agreement with latest solar UV proxy reconstructions that exploit more sophisticated techniques requiring historical full-disk observations. This makes us confident that our technique can represent an alternative approach which can complement classical solar reconstruction efforts. Moreover, this technique, based on broad-band observations, can be utilized to estimate the activity on Sun-like stars, that cannot be resolved spatially, hosting extra-solar planetary systems.

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Field testing of single instrumented steel driven batter piles under vertical vibrations     

Ralli  Rohit  Manna  Bappaditya  Datta  Manoj 《Acta Geotechnica》2022,17(6):2415-2434

Acta Geotechnica - The forced vertical vibration tests were performed in the field on 3.3-m-long driven steel pipe on a single vertical pile, P1 (β?=?0°), and single batter...  相似文献   

Mechanisms for the land/sea warming contrast exhibited by simulations of climate change   总被引：3，自引：3，他引：0  

Manoj M. Joshi  Jonathan M. Gregory  Mark J. Webb  David M. H. Sexton  Tim C. Johns 《Climate Dynamics》2008,30(5):455-465

The land/sea warming contrast is a phenomenon of both equilibrium and transient simulations of climate change: large areas of the land surface at most latitudes undergo temperature changes whose amplitude is more than those of the surrounding oceans. Using idealised GCM experiments with perturbed SSTs, we show that the land/sea contrast in equilibrium simulations is associated with local feedbacks and the hydrological cycle over land, rather than with externally imposed radiative forcing. This mechanism also explains a large component of the land/sea contrast in transient simulations as well. We propose a conceptual model with three elements: (1) there is a spatially variable level in the lower troposphere at which temperature change is the same over land and sea; (2) the dependence of lapse rate on moisture and temperature causes different changes in lapse rate upon warming over land and sea, and hence a surface land/sea temperature contrast; (3) moisture convergence over land predominantly takes place at levels significantly colder than the surface; wherever moisture supply over land is limited, the increase of evaporation over land upon warming is limited, reducing the relative humidity in the boundary layer over land, and hence also enhancing the land/sea contrast. The non-linearity of the Clausius–Clapeyron relationship of saturation specific humidity to temperature is critical in (2) and (3). We examine the sensitivity of the land/sea contrast to model representations of different physical processes using a large ensemble of climate model integrations with perturbed parameters, and find that it is most sensitive to representation of large-scale cloud and stomatal closure. We discuss our results in the context of high-resolution and Earth-system modelling of climate change.  相似文献   

Long-Term Variability of Nutrients and Chlorophyll in the Chesapeake Bay: A Retrospective Analysis, 1985–2008     

M. Bala Krishna Prasad  Mathew R. P. Sapiano  Clarissa R. Anderson  Wen Long  Raghu Murtugudde 《Estuaries and Coasts》2010,33(5):1128-1143

A retrospective analysis of freshwater discharge, riverine dissolved nutrient loads, dissolved nutrients, and chlorophyll in the Chesapeake Bay from 1985 to 2008 is presented. It is evident that each field displays an interannual variability averaged over the Bay. The N and P loads peaked in 1997 and have fluctuated with a decreasing trend since early 2004. Dissolved nutrient concentrations in the Bay appear to be largely controlled by riverine nutrient loads. The temporal variability of chlorophyll is positively correlated with nutrient loads and concentrations. Over the study period, N:P (DIN:DIP) molar ratios were consistently higher than the Redfield ratio (N:P?=?16:1) and strongly correlated with river discharge (R ²?=?0.68, p??16:1), and N is the limiting nutrient in summer and early autumn (N:P?4 from anoxic sediments. Long-term climate indices, such as El Niño Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO), appear to exert only a moderate control over the riverine discharge to the Bay or over the ecosystem response in terms of chlorophyll in the Bay. While not all related mechanisms can be inferred from available data, this analysis should help in determining future data needs for monitoring water quality and human and climate influence on the health of the Bay.  相似文献   

Impact of seismic factors on landslide susceptibility zonation: a case study in part of Indian Himalayas   总被引：6，自引：0，他引：6  

Naveen Pareek  Mukat L. Sharma  Manoj K. Arora 《Landslides》2010,7(2):191-201

Landslides are one of the most widespread natural hazards in high mountain terrains such as the Himalayas, which are one of the youngest tectonically and seismically active mountain ranges in the world. The crustal movements along the longitudinal thrusts and transverse faults give rise to earthquakes and in turn initiate landslides in the region. In fact, in addition to various static factors causing landslides, earthquakes are one of the major causes of landslides. It is thus imperative to incorporate seismic factor also while carrying out landslide susceptibility zonation map preparation in a seismically active areas like Garhwal Himalayas. In this paper, a study on the effect of earthquakes on landslide susceptibility zonation has been demonstrated by taking Chamoli earthquake as an example.  相似文献