Mid-term periodicities and heliospheric modulation of coronal index and solar flare index during solar cycles 22–23     

Prithvi Raj Singh  A. K. Saxena  C. M. Tiwari 《Journal of Astrophysics and Astronomy》2018,39(2):20

We applied fast Fourier transform techniques and Morlet wavelet transform on the time series data of coronal index, solar flare index, and galactic cosmic ray, for the period 1986–2008, in order to investigate the long- and mid-term periodicities including the Rieger (\({\sim }130\) to \({\sim }190\) days), quasi-period (\({\sim }200\) to \({\sim }374\) days), and quasi-biennial periodicities (\({\sim }1.20\) to \({\sim }3.27\) years) during the combined solar cycles 22–23. We emphasize the fact that a lesser number of periodicities are found in the range of low frequencies, while the higher frequencies show a greater number of periodicities. The rotation rates at the base of convection zone have periods for coronal index of \({\sim }1.43\) years and for solar flare index of \({\sim }1.41\) year, and galactic cosmic ray, \({\sim }1.35\) year, during combined solar cycles 22–23. In relation to these two solar parameters (coronal index and solar flare index), for the solar cycles 22–23, we found that galactic cosmic ray modulation at mid cut-off rigidity (\(\hbox {Rc} = 2.43\hbox {GV}\)) is anti-correlated with time-lag of few months.  相似文献   

A model of Earth’s deep interior basedon mineralogical data     

S. K. Saxena  P. Lazor  L. S. Dubrovinsky 《Mineralogy and Petrology》2000,69(1-2):1-10

Summary ?We describe here a model of formation of the core and the early history of Earth based on recent experimental mineralogical data. In a nebular setting, where differentiated planetesimals with their iron cores were plentiful, hot condensing solids mixed with the planetesimal irons and formed the solid proto-core (Fe-Ni-S-C). FeO from unmixing in magnesiowustite and from a dissociation of perovskite in the newly accreted mantle concentrated at the core-mantle interface and reacted with the nascent core. The interface grew to form the liquid core (Fe-Ni-O-S-C) at the expense of the solid proto-core and the formation of much of the outer core was complete within the first 500 million years. The model is consistent with geochemical data and has important implications for the dynamics of the inner core.

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Zusammenfassung ?Das Innere der Erde: Ein Modell basierend auf mineralogischen Daten Wir pr?sentieren ein Modell zur Bildung des Erdkerns und der frühen Geschichte der Erde, das auf neuen experimentellen mineralogischen Daten basiert. In einem nebularen System, in dem differenzierte Planetesimals mit Eisenkernen sehr h?ufig waren, mischten sich kondensierte Festk?rper mit dem Eisen der Planetesimals, um einen festen Protokern (Fe-Ni-S-C) zu formen. FeO, das aus Magnesiowüstit entmischte und durch Dissoziation aus Perovskit im Mantel entstand, konzentrierte sich in der Kern – Mantel – Grenzzone und reagierte mit dem neugebildeten Kern. Diese Grenzzone wuchs und es entstand ein flüssiger (Fe-Mi-O-S-C) Kern auf Kosten des festen Protokerns. Die Bildung des ?u?eren Kerns war innerhalb der ersten 500 Millionen Jahre abgeschlossen. Dieses Modell ist mit geochemischen Daten konsistent und hat wichtige Auswirkungen auf die Dynamik des inneren Kerns.

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Received February 9, 1999;/revised version accepted April 9, 1999  相似文献   

Spatio-temporal variations of respirable particles at residential areas located in the vicinity of opencast coal projects,India: a case study     

Satya Prakash Sahu  Manish Yadav  Dhruti Sundar Pradhan  Neha Rani  Arka Jyoti Das 《Arabian Journal of Geosciences》2018,11(10):241

The objective of the study is to investigate spatio-temporal variations of PM₁₀, PM_2.5, and PM₁ concentrations at seven residential sites, located in the vicinity of opencast coal projects, Basundhara Garjanbahal Area (BGA), India. Meteorological parameters such as wind speed, wind direction, relative humidity, and temperature were collected simultaneously with PM concentrations. Mean concentrations of PM₁₀ in the range 215 ± 169–526 ± 412 μg m^?3, PM_2.5 in the range of 91 ± 79–297 ± 107 μg m^?3, PM₁ in the range of 68 ± 60–247 ± 84 μg m^?3 were obtained. Coarse fractions (PM_2.5–10) varied from 27 to 58% whereas fine fractions (PM_1–2.5 and PM₁) varied in the range of 51–73%. PM_2.5 concentration was 41–74% of PM₁₀ concentration, PM₁ concentration was 31–62% of PM₁₀ concentration, and PM₁ concentration was 73–83% of PM_2.5 concentration. Role of meteorology on PM concentrations was assessed using correlation analysis. Linear relationships were established among PM concentrations using least square regression analysis. With the aid of principal component analysis, two components were drawn out of eight variables, which represent more than 75% of variance. The results indicated that major sources of air pollutants (PM₁₀, PM_2.5, PM₁, CO, CO₂) at the residential sites are road dust raised by vehicular movement, spillage of coal generated during transportation, spontaneous combustion of coal, and biomass burning in village area.  相似文献   

A distributed parallel multiple-relaxation-time lattice Boltzmann method on general-purpose graphics processing units for the rapid and scalable computation of absolute permeability from high-resolution 3D micro-CT images     

F. O. Alpak  F. Gray  N. Saxena  J. Dietderich  R. Hofmann  S. Berg 《Computational Geosciences》2018,22(3):815-832

Digital rock physics (DRP) is a rapidly evolving technology targeting fast turnaround times for repeatable core analysis and multi-physics simulation of rock properties. We develop and validate a rapid and scalable distributed-parallel single-phase pore-scale flow simulator for permeability estimation on real 3D pore-scale micro-CT images using a novel variant of the lattice Boltzmann method (LBM). The LBM code implementation is designed to take maximum advantage of distributed computing on multiple general-purpose graphics processing units (GPGPUs). We describe and extensively test the distributed parallel implementation of an innovative LBM algorithm for simulating flow in pore-scale media based on the multiple-relaxation-time (MRT) model that utilizes a precise treatment of body force. While the individual components of the resulting simulator can be separately found in various references, our novel contributions are (1) the integration of all of the mathematical and high-performance computing components together with a highly optimized code implementation and (2) the delivery of quantitative results with the simulator in terms of robustness, accuracy, and computational efficiency for a variety of flow geometries including various types of real rock images. We report on extensive validations of the simulator in terms of accuracy and provide near-ideal distributed parallel scalability results on large pore-scale image volumes that were largely computationally inaccessible prior to our implementation. We validate the accuracy of the MRT-LBM simulator on model geometries with analytical solutions. Permeability estimation results are then provided on large 3D binary microstructures including a sphere pack and rocks from various sandstone and carbonate formations. We quantify the scalability behavior of the distributed parallel implementation of MRT-LBM as a function of model type/size and the number of utilized GPGPUs for a panoply of permeability estimation problems.  相似文献   

Environmental impact on coastal wetlands since 4 ka in Cauvery Delta: Palynology and thecamoebian study     

Jyoti Srivastava  Anjum Farooqui 《Journal of the Geological Society of India》2014,84(4):459-466

Palaeoclimate and Palaeoecological study was carried out in ～2 m sediment core deposited since 4 ka in an estuarine environment along Uppanar River mouth, Cauvery Delta. Palynological and thecamoebian evidences indicate (1) a basal fluvial lacustrine depositional environment (～4–3 ka) characterized by sandy sediment, with low salinity and dominance of non-pollen forms like foraminiferal linings and thecamoebians with a low percentage of pollen and spores and (2) an estuarine environment (since 3 ka) characterized by clayey sediment with high salinity and a good percentage of mangrove and terrestrial pollen along with non-pollen forms. A shift in the depositional environment since ～3 ka indicates monsoonal and geomorphological changes in the coastal wetland. During this period dominance of Avicennia and Cheno/Ams indicate low freshwater runoff from land suggesting a weakened monsoon condition enhanced by anthropogenic activity.  相似文献   

Resource Flows of Villages with Contrasting Lifestyles in Nanda Devi Biosphere Reserve, Central Himalaya, India   总被引：1，自引：0，他引：1  

K. S. Rao S. Nautiyal R. K. Maikhuri K. G. Saxena 《山地科学学报》2005,2(4):271-293

Resource use efficiency analyses of village ecosystem are necessary for effective and efficient planning of resource utilization. This paper deals with economic and energy input-output analyses of different components of village ecosystem in representative buffer zone villages, which are practicing transhumance and settled way of lifestyles in Nanda Devi Biosphere Reserve （NDBR） of Garhwal Himalaya. While the villages practicing transhumance used various natural resources spatially segregated,the villages practicing settled way of lifestyle have to manage resources from a limited spatial area through rotation and varied extraction intensities. Forests subsidized the production activity in both type of villages and the per capita resource extractions were found to be greater in tran~humance village than settled village. Though crops provided maximum energy, in terms of economic criteria, animal husbandry played important role in both settled and transhumance villages. As villages representing both the situations showed different ways of adjustments to the conservation oriented land use changes, management authority needs to address the eco-development plans fulfilling the aspirations of all people traditionally using the resources of the Reserve to reduce the conflicts and encourage their participation in the conservation of the area.  相似文献   

Reaction-Diffusion Systems and Nonlinear Waves     

R. K. Saxena  A. M. Mathai  H. J. Haubold 《Astrophysics and Space Science》2006,305(3):297-303

The authors investigate the solution of a nonlinear reaction-diffusion equation connected with nonlinear waves. The equation discussed is more general than the one discussed recently by Manne et al. (2000). The results are presented in a compact and elegant form in terms of Mittag-Leffler functions and generalized Mittag-Leffler functions, which are suitable for numerical computation. The importance of the derived results lies in the fact that numerous results on fractional reaction, fractional diffusion, anomalous diffusion problems, and fractional telegraph equations scattered in the literature can be derived, as special cases, of the results investigated in this article.  相似文献   

Changes in Agricultural Biodiversity： Implications for Sustainable Livelihood in the Himalaya   总被引：6，自引：1，他引：5  

K.G.Saxena R.K.Maikhuri K.S.Rao 《山地科学学报》2005,2(1):23-31

Himalayan mountain system is distinguished globally for a rich biodiversity and for its role in regulating the climate of the South Asia.Traditional crop-livestock mixed farming in the Himalaya is highly dependent on forests for fodder and manure prepared from forest leaf litter and livestock excreta. Apart from sustaining farm production, forests provide a variety of other tangible and intangible benefits, which are critical for sustainable livelihood of not only 115 million mountain people, but also many more people living in the adjoining plains. Extension of agricultural landuse coupled with replacement of traditional staple food crops by cash crops and of multipurpose agroforestry trees by fruit trees are widespread changes. Cultivation of Fagopyrum esculentum,Fagopyrum tataricum, Panicum miliaceum, Setaria italica and Pisum arvense has been almost abandoned. Increasing stress on cash crops is driven by a socio-cultural change from subsistence to market economy facilitated by improvement in accessibility and supply of staple food grains at subsidized price by the government. Farmers have gained substantial economic benefits from cash crops. However, loss of agrobiodiversity implies more risks to local livelihood in the events of downfall in market price/demand of cash crops, termination of supply of staple food grains at subsidized price, pest outbreaks in a cash crop dominated homogeneous landscape and abnormal climate years. Indigenous innovations enabling improvement in farm economy by conserving and/enhancing agrobiodiversity do exist, but are highly localized. The changes in agrobiodiversity are such that soil loss and run-off from the croplands have dramatically increased together with increase in local pressure on forests. As farm productivity is maintained with forest-based inputs, continued depletion of forest resources will result in poor economic returns from agriculture to local people,apart from loss of global benefits from Himalayan forests. Interventions including improvement in traditional manure and management of on-farm trees,participatory development of agroforestry in degraded forest lands and policies favoring economic benefits to local people from non-timber forest products could reduce the risks of decline in agricultural biodiversity and associated threats to livelihoods and Himalayan ecosystems.  相似文献   

Infrared spectroscopic observations of 69230 Hermes (1937 UB): possible unweathered endmember among ordinary chondrite analogs     

A.S. Rivkin  R.P. Binzel  S.J. Bus  A. Saxena 《Icarus》2004,172(2):408-414

We have obtained near-infrared (0.8-2.5 μm) spectra of Hermes (1937 UB) using the NASA Infrared Telescope Facility on Mauna Kea. We find Hermes to have spectral properties consistent with L/LL chondrites, with a strong visual similarity to Gaffey (1976, J. Geophys. Res. 81, 905) average L6 chondrites. We define a ratio of band areas (RBA) using the Modified Gaussian Method (MGM: Sunshine and Pieters, 1990, in: Lunar and Planetary Institute Conference Abstracts, p. 1223, 1993, J. Geophys. Res. 98, 9075) to quantify near-infrared asteroidal data lacking a visible component. Hermes has a spectrum nearly indistinguishable from (19356) 1997 GH3. Together, these asteroids represent new endmembers on the continuum of spectra from ordinary chondrite meteorites to large main-belt S-class asteroids. We discuss regolith effects that may be occurring on Hermes and other possible ordinary chondrite parent bodies, and constrain the albedo of Hermes to 0.4 or higher (effective diameter 650 m or smaller) if it has a regolith. This value for albedo/diameter is consistent with radar results.  相似文献   

Optimization of spatial statistical approaches to identify land use/land cover change hot spots of Pune region of Maharashtra using remote sensing and GIS techniques     

Kuntal Ganguly  Rajiv Kumar  K. Mruthyunjaya Reddy  P. Jagadeeswara Rao  Manoj Raj Saxena  G. Ravi Shankar 《国际地球制图》2017,32(7):777-796

This study investigated land use/land cover change (LULCC) dynamics using temporal satellite images and spatial statistical cluster analysis approaches in order to identify potential LULCC hot spots in the Pune region. LULCC hot spot classes defined as new, progressive and non-progressive were derived from Gi* scores. Results indicate that progressive hot spots have experienced high growth in terms of urban built-up areas (20.67% in 1972–1992 and 19.44% in 1992–2012), industrial areas (0.73% in 1972–1992 and 3.46% in 1992–2012) and fallow lands (4.35% in 1972–1992 and ?6.38% in 1992–2012). It was also noticed that about 28.26% of areas near the city were identified as new hot spots after 1992. Hence, non-significant change areas were identified as non-progressive after 1992. The study demonstrated that LULCC hot spot mapping through the integrated spatial statistical approach was an effective approach for analysing the direction, rate, spatial pattern and spatial relationship of LULCC.  相似文献