A comparative analysis of pansharpening techniques on QuickBird and WorldView-3 images     

Snehmani  Ashwagosh Ganju  Satish Kumar  P. K. Srivastava  Hari Ram R P 《国际地球制图》2017,32(11):1268-1284

Nowadays, different image pansharpening methods are available, which combine the strengths of different satellite images that have different spectral and spatial resolutions. These different image fusion methods, however, add spectral and spatial distortions to the resultant images depending on the required context. Therefore, a careful selection of the fusion method is required. Simultaneously, it is also essential that the fusion technique should be efficient to cope with the large data. In this paper, we investigated how different pansharpening algorithms perform, when applied to very high-resolution WorldView-3 and QuickBird satellite images effectively and efficiently. We compared these 27 pansharpening techniques in terms of quantitative analysis, visual inspection and computational complexity, which has not previously been formally tested. In addition, 12 different image quality metrics available in literature are used for quantitative analysis purpose.  相似文献   

Assessing the influence of watershed characteristics on soil erosion susceptibility of Jhelum basin in Kashmir Himalayas     

Muzamil Ahmad Rather  J Satish Kumar  Majid Farooq  Humayan Rashid 《Arabian Journal of Geosciences》2017,10(3):59

Soil erosion, a serious environmental problem, is a global challenge. Once a portion of a fertile soil is lost, it is very difficult to replace it, and this leads to decrease in crop production, damage to drainage networks, and siltation of dams and reservoirs. Human practices like intensive agriculture, overgrazing, and deforestation have intensified the rate of soil erosion all over the world. The Jhelum basin which forms the north-western part of the complex mountain system Himalayas is not only highly vulnerable to natural hazards like earthquakes, landslides, and floods but is also highly susceptible to soil erosion. There is an immediate need to device strategies to reduce adverse impacts of soil erosion and to conserve natural resources like soil, water, and forests by means of proper watershed management programs in the Himalayan region. The present study is carried out for eight upper watersheds of Jhelum basin, an area which are facing serious issues like boulder extraction, deforestation, and unplanned urbanization. The present work demonstrates the use of morphometry, land use, and slope coupled with the multicriteria analytical (MCA) framework to estimate the soil erosion susceptibility of these watersheds using Remote Sensing and Geographical Information System techniques. The present study revealed that out of eight upper watersheds, Arapal, Lidder, and Bringi fall in high priority and need immediate attention and measures to reduce soil erosion in the area. Sandran, Rembiara, and Romshii fall in medium priority. Kuthar and Vishav fall in the low-priority category and are least susceptible to soil erosion.  相似文献   

A simulation study of capillary transport,preferential retention and distribution of salts in historic sandstone buildings     

Satish C. Pandey  A. M. Pollard  H. A. Viles 《Environmental Earth Sciences》2017,76(12):434

Salt crystallisation is a major problem of deterioration in historic stone buildings, monuments and sculptures. The capillary rise of soil water is one of the primary sources of salts in stone structures, which evaporates leaving the salts behind. It has been noted that the spatial distribution profile of different species of salts crystallised in historic stone buildings is not homogeneous, i.e. different salts crystallise at different locations. The capillary transport and inhomogeneous spatial distribution of different salts in the porous building materials has been considered to be a result of solubility-dependent crystallisation; however, the factors responsible for this phenomenon are not clearly known. This paper aims to investigate the factors influencing the differential distribution of salts during capillary rise of soil water. In this study, the capillary transport of salts was simulated on two different sandstones—Locharbriggs, a Permo–Triassic, red sandstone and Stoke Hall, a Carboniferous, buff sandstone. The experiments were carried out under controlled environmental conditions to eliminate the possibility of evaporation-driven crystallisation of salts depending on their solubilities. The results indicate that fractionation or differential distribution of salts takes place even in the absence of evaporation and crystallisation. The sandstones exhibit properties like an ion exchange column, and ionic species present in the salt solution show differential distribution within the porous network of sandstone.  相似文献   

Laplace–Fourier-Domain Full Waveform Inversion of Deep-Sea Seismic Data Acquired with Limited Offsets     

Yongchae Cho  Wansoo Ha  Youngseo Kim  Changsoo Shin  Satish Singh  Eunjin Park 《Pure and Applied Geophysics》2016,173(3):749-773

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Numerical simulations of a highway bridge structure employing passive negative stiffness device for seismic protection          下载免费PDF全文

Navid Attary  Michael Symans  Satish Nagarajaiah  Andrei M. Reinhorn  Michael C. Constantinou  Apostolos A. Sarlis  Dharma T. R. Pasala  Douglas Taylor 《地震工程与结构动力学》2015,44(6):973-995

A new passive seismic response control device has been developed, fabricated, and tested by the authors and shown to be capable of producing negative stiffness via a purely mechanical mechanism, thus representing a new generation of seismic protection devices. Although the concept of negative stiffness may appear to be a reversal on the desired relationship between the force and displacement in structures (the desired relationship being that the product of restoring force and displacement is nonnegative), when implemented in parallel with a structure having positive stiffness, the combined system appears to have substantially reduced stiffness while remaining stable. Thus, there is an ‘apparent weakening and softening’ of the structure that results in reduced forces and increased displacements (where the weakening and softening is of a non‐damaging nature in that it occurs in a seismic protection device rather than within the structural framing system). Any excessive displacement response can then be limited by incorporating a damping device in parallel with the negative stiffness device. The combination of negative stiffness and passive damping provides a large degree of control over the expected performance of the structure. In this paper, a numerical study is presented on the performance of a seismically isolated highway bridge model that is subjected to various strong earthquake ground motions. The Negative Stiffness Devices (NSDs) are described along with their hysteretic behavior as obtained from a series of cyclic tests wherein the tests were conducted using a modified design of the NSDs (modified for testing within the bridge model). Using the results from the cyclic tests, numerical simulations of the seismic response of the isolated bridge model were conducted for various configurations (with/without negative stiffness devices and/or viscous dampers). The results demonstrate that the addition of negative stiffness devices reduces the base shear substantially, while the deck displacement is limited to acceptable values. This assessment was conducted as part of a NEES (Network for Earthquake Engineering Simulation) project which included shaking table tests of a quarter‐scale highway bridge model. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Geotechnical Aspects of Clayey Sediments Off Badagara on the Kerala Coast,India     

Dr. Thomas Mathai  K. N. Rajarama  Satish Kumar  M. Suresh Chandran  M. R. Asoka Kumar 《Marine Georesources & Geotechnology》2013,31(2):180-193

Offshore geotechnical surveys form part of an integrated investigation to rejuvenate a decrepit minor port at Badagara, Kerala on the southwestern coast of India. The sediments typify a fluvio-marine milieu ranging from silty clay, sand, silty sand, sandy silt and clayey silt. Geotechnical and sedimentological studies of shallow cores reveal the geotechnical aspects besides the depositional history of the sediments. Downcore geotechnical variations and regressive coefficients based on their inter-relationships highlight diverse factorial inferences. X-Ray Diffraction data indicate the prominent clay type.

A comparative evaluation of the geotechnical characteristics of clayey sediments off Badagara, with similar studies along various sectors of the Kerala coast, both on land as well as in the near shore, is broadly attempted. Geotechnical studies carried out earlier on the uplifted Cochin marine clays provide comparative data for evaluating the possible variations between present day marine clayey sediments occurring along the Kerala coast and uplifted marine clays which, besides their gross variations in levels with respect to the present sea-level, also obviously relate to a much older depositional environment and provenance during probable Holocene times.  相似文献   

Comparison of microclimate vs. remote meteorological data and results applied to a water temperature model (Miramichi River,Canada)     

Loubna Benyahya  Daniel Caissie  Nassir El-Jabi  Mysore G. Satish 《Journal of Hydrology》2010,380(3-4):247-259

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Soil Iodine Determination in Deccan Syneclise,India: Implications for Near Surface Geochemical Hydrocarbon Prospecting     

Devleena Mani  T. Satish Kumar  M. A. Rasheed  D. J. Patil  A. M. Dayal  T. Gnaneshwar Rao  V. Balaram 《Natural Resources Research》2011,20(1):75-88

The association of iodine with organic matter in sedimentary basins is well documented. High iodine concentration in soils overlying oil and gas fields and areas with hydrocarbon microseepage has been observed and used as a geochemical exploratory tool for hydrocarbons in a few studies. In this study, we measure iodine concentration in soil samples collected from parts of Deccan Syneclise in the west central India to investigate its potential application as a geochemical indicator for hydrocarbons. The Deccan Syneclise consists of rifted depositional sites with Gondwana–Mesozoic sediments up to 3.5 km concealed under the Deccan Traps and is considered prospective for hydrocarbons. The concentration of iodine in soil samples is determined using ICP-MS and the values range between 1.1 and 19.3 ppm. High iodine values are characteristic of the northern part of the sampled region. The total organic carbon (TOC) content of the soil samples range between 0.1 and 1.3%. The TOC correlates poorly with the soil iodine (r ² < 1), indicating a lack of association of iodine with the surficial organic matter and the possibility of interaction between the seeping hydrocarbons and soil iodine. Further, the distribution pattern of iodine compares well with two surface geochemical indicators: the adsorbed light gaseous hydrocarbons (methane through butane) and the propane-oxidizing bacterial populations in the soil. The integration of geochemical observations show the occurrence of elevated values in the northern part of the study area, which is also coincident with the presence of exposed dyke swarms that probably serve as conduits for hydrocarbon microseepage. The corroboration of iodine with existing geological, geophysical, and geochemical data suggests its efficacy as one of the potential tool in surface geochemical exploration of hydrocarbons. Our study supports Deccan Syneclise to be promising in terms of its hydrocarbon prospects.  相似文献   

Sediment shear properties from seafloor compliance measurements: Faroes-Shetland basin case study     

Wayne C. Crawford  Satish C. Singh 《Geophysical Prospecting》2008,56(3):313-325

Shear properties provide important information about the lithology, fluid content and stability of sediments but are difficult to measure using conventional seismics in the marine environment. Seafloor compliance measurements are sensitive to subsurface shear properties but have only been used in the Pacific Ocean and on shallow coastal shelves, where the source wave energy is known to be strong. We show here that seafloor compliance measurements can provide useful information about shear properties of marine sediments in less energetic settings and under high noise conditions caused by strong seafloor currents. We measured compliance at three sites in the Faroes‐Shetland sedimentary basin north of the Atlantic ocean. The sites have 1000 times higher noise levels than quiet seafloor sites and the source wave power is highly variable, but the data still reveal significant differences in sediment properties between two sites down to 2 kilometres beneath the seafloor. The first site, at the northern end of the basin, has an average shear velocity of 400 m/s in the upper 0.6 kilometres beneath the seafloor, increasing to approximately 2100 m/s at 2 kilometres beneath the seafloor. The second site, further south and to the west of the basin axis, has an average shear velocity of 150 m/s in the upper 0.6 kilometres beneath the seafloor, increasing to 1400 m/s at 2 kilometres beneath the seafloor. The sediments are probably unconsolidated in the upper 0.6 kilometres beneath the seafloor at both sites, with a mean grain size of 1 μm at the southern site and 20 μm at the northern site. The southern site has higher porosity at all depths and a higher risk of borehole collapse during drilling.  相似文献   

Receiver function method in reflection seismology     

Pascal Edme  Satish C. Singh 《Geophysical Prospecting》2008,56(3):327-340

The receiver function method was originally developed to analyse earthquake data recorded by multicomponent (3C) sensors and consists in deconvolving the horizontal component by the vertical component. The deconvolution process removes travel path effects from the source to the base of the target as well as the earthquake source signature. In addition, it provides the possibility of separating the emergent P and PS waves based on adaptive subtraction between recorded components if plane waves of constant ray parameters are considered. The resulting receiver function signal is the local PS wave's impulse response generated at impedance contrasts below the 3C receiver.We propose to adapt this technique to the wide‐angle multi‐component reflection acquisition geometry. We focus on the simplest case of land data reflection acquisition. Our adapted version of the receiver function approach consists in a multi‐step procedure that first removes the P wavefield recorded on the horizontal component and next removes the source signature. The separation step is performed in the τ?p domain while the source designature can be achieved in either the τ?p or the t?x domain. Our technique does not require any a priori knowledge of the subsurface. The resulting receiver function is a pure PS‐wave reflectivity response, which can be used for amplitude versus slowness or offset analysis. Stack of the receiver function leads to a high‐quality S wave image.  相似文献