Cohesive/cohesionless sediment transition diameter from settling velocity data     

Ashish J. Mehta  Joseph V. Letter Jr. 《Ocean Dynamics》2015,65(9-10):1213-1219

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Policies and pattern of industrial development in Thailand     

Apisek?PansuwanEmail author  Jayant?K.?Routray 《GeoJournal》2011,76(1):25-46

Spatial concentration of manufacturing always ends up with regional inequalities. This phenomenon is also true in the case of Thailand. The pattern of industrial development in Thailand from 1996 to 2005 was examined using composite index in analyzing the pattern, the results of which are described in this paper. The review was aimed at assessing the effects of development policies and the factors that influenced the concentration of industrial development in the country. Results of the analysis indicated that most industries are concentrated only in Bangkok and its vicinity even if the Government of Thailand has promoted investment policies to support and develop provincial industries in the remote rural areas. Moreover, the results also showed that capital intensive based industries are concentrated in the urban areas, while the resources-based industries are mainly found in the rural areas. Despite wide zonal variation of industrial development within Thailand, the outcomes of the industrial decentralization policy are very impressive and leading to the path of greater success in coming decades.  相似文献   

Status of NCEP CFS vis-a-vis IPCC AR4 models for the simulation of Indian summer monsoon     

Samir Pokhrel  Ashish Dhakate  Hemantkumar S. Chaudhari  Subodh K. Saha 《Theoretical and Applied Climatology》2013,111(1-2):65-78

National Centers for Environmental Prediction (NCEP) Coupled Forecast System (CFS) is selected to play a lead role for monsoon research (seasonal prediction, extended range prediction, climate prediction, etc.) in the ambitious Monsoon Mission project of Government of India. Thus, as a prerequisite, a detail analysis for the performance of NCEP CFS vis-a-vis IPCC AR4 models for the simulation of Indian summer monsoon (ISM) is attempted. It is found that the mean monsoon simulations by CFS in its long run are at par with the IPCC models. The spatial distribution of rainfall in the realm of Indian subcontinent augurs the better results for CFS as compared with the IPCC models. The major drawback of CFS is the bifurcation of rain types; it shows almost 80–90 % rain as convective, contrary to the observation where it is only 50–65 %; however, the same lacuna creeps in other models of IPCC as well. The only respite is that it realistically simulates the proper ratio of convective and stratiform rain over central and southern part of India. In case of local air–sea interaction, it outperforms other models. However, for monsoon teleconnections, it competes with the better models of the IPCC. This study gives us the confidence that CFS can be very well utilized for monsoon studies and can be safely used for the future development for reliable prediction system of ISM.  相似文献   

Anisotropic cosmological model with variable G and Λ     

S. K. Tripathy  D. Behera  T. R. Routray 《Astrophysics and Space Science》2012,340(2):211-215

Anisotropic Bianchi-III cosmological model is investigated with variable gravitational and cosmological constants in the framework of Einstein’s general relativity. The shear scalar is considered to be proportional to the expansion scalar. The dynamics of the anisotropic universe with variable G and Λ are discussed. Without assuming any specific forms for Λ and the metric potentials, we have tried to extract the time variation of G and Λ from the anisotropic model. The extracted G and Λ are in conformity with the present day observations. Basing upon the observational limits, the behavior and range of the effective equation of state parameter are discussed.  相似文献   

String fluid cosmological models in general relativity     

S. K. Tripathy  S. K. Nayak  S. K. Sahu  T. R. Routray 《Astrophysics and Space Science》2008,318(1-2):125-131

LRS Bianchi type-I string cosmological models are studied in the frame work of general relativity when the source for the energy momentum tensor is a bulk viscous fluid containing one dimensional strings embedded in electromagnetic field. A barotropic equation of state for the pressure and density is assumed to get determinate solutions of the field equations. The bulk viscosity is assumed to be inversely proportional to the scalar expansion. The physical and kinematical properties of the models are discussed. The effect of viscosity and electromagnetic field on the physical and kinematical properties is also investigated.  相似文献   

String cloud cosmologies for Bianchi type-III models with electromagnetic field     

S. K. Tripathy  S. K. Sahu  T. R. Routray 《Astrophysics and Space Science》2008,315(1-4):105-110

The Saez-Ballester field equations for spatially homogeneous and anisotropic Bianchi type-III cosmological models have been solved for pure geometric cosmic string cloud pervading the universe either in the absence or in presence of electromagnetic field. It has been established here that the model does not survive for geometric cosmic string cloud pervading the universe when there is no electromagnetic field. But in presence of electromagnetic field the model can have plausible solutions fostering the idea that strings forming the surface of the world sheet have to co-exist with electromagnetic field.  相似文献   

Soil erosion modeling of a Himalayan watershed using RS and GIS   总被引：5，自引：1，他引：4  

Ashish Pandey  Abhisekh Mathur  S. K. Mishra  B. C. Mal 《Environmental Earth Sciences》2009,59(2):399-410

Employing the remote sensing (RS) and geographical information system (GIS), an assessment of sediment yield from Dikrong river basin of Arunachal Pradesh (India) has been presented in this paper. For prediction of soil erosion, the Morgan-Morgan and Finney (MMF) model and the universal soil loss equation (USLE) have been utilized at a spatial grid scale of 100 m × 100 m, an operational unit. The average annual soil loss from the Dikrong river basin is estimated as 75.66 and 57.06 t ha⁻¹ year⁻¹ using MMF and USLE models, respectively. The watershed area falling under the identified very high, severe, and very severe zones of soil erosion need immediate attention for soil conservation.  相似文献   

Evaluation of the Soil Conservation Service curve number methodology using data from agricultural plots   总被引：1，自引：0，他引：1  

Mohan Lal  S. K. Mishra  Ashish Pandey  R. P. Pandey  P. K. Meena  Anubhav Chaudhary  Ranjit Kumar Jha  Ajit Kumar Shreevastava  Yogendra Kumar 《Hydrogeology Journal》2017,25(1):151-167

The Soil Conservation Service curve number (SCS-CN) method, also known as the Natural Resources Conservation Service curve number (NRCS-CN) method, is popular for computing the volume of direct surface runoff for a given rainfall event. The performance of the SCS-CN method, based on large rainfall (P) and runoff (Q) datasets of United States watersheds, is evaluated using a large dataset of natural storm events from 27 agricultural plots in India. On the whole, the CN estimates from the National Engineering Handbook (chapter 4) tables do not match those derived from the observed P and Q datasets. As a result, the runoff prediction using former CNs was poor for the data of 22 (out of 24) plots. However, the match was little better for higher CN values, consistent with the general notion that the existing SCS-CN method performs better for high rainfall–runoff (high CN) events. Infiltration capacity (fc) was the main explanatory variable for runoff (or CN) production in study plots as it exhibited the expected inverse relationship between CN and fc. The plot-data optimization yielded initial abstraction coefficient (λ) values from 0 to 0.659 for the ordered dataset and 0 to 0.208 for the natural dataset (with 0 as the most frequent value). Mean and median λ values were, respectively, 0.030 and 0 for the natural rainfall–runoff dataset and 0.108 and 0 for the ordered rainfall–runoff dataset. Runoff estimation was very sensitive to λ and it improved consistently as λ changed from 0.2 to 0.03.  相似文献   

ENSO, IOD and Indian Summer Monsoon in NCEP climate forecast system     

Samir Pokhrel  H. S. Chaudhari  Subodh K. Saha  Ashish Dhakate  R. K. Yadav  Kiran Salunke  S. Mahapatra  Suryachandra A. Rao 《Climate Dynamics》2012,39(9-10):2143-2165

El Ni?o-Southern Oscillation (ENSO), Indian Ocean Dipole (IOD) and Indian Summer Monsoon rainfall features are explored statistically and dynamically using National Centers for Environment Prediction (NCEP) Climate Forecast System (CFSv1) freerun in relation to observations. The 100?years of freerun provides a sufficiently long homogeneous data set to find out the mean state, periodicity, coherence among these climatic events and also the influence of ENSO and IOD on the Indian monsoon. Differences in the occurrence of seasonal precipitation between the observations and CFS freerun are examined as a coupled ocean–atmosphere system. CFS simulated ENSO and IOD patterns and their associated tropical Walker and regional Hadley circulation in pure ENSO (PEN), pure IOD (PIO) and coexisting ENSO-IOD (PEI) events have some similarity to the observations. PEN composites are much closer to the observation as compared to PIO and PEI composites, which suggest a better ENSO prediction and its associated teleconnections as compared to IOD and combined phenomenon. Similar to the observation, the model simulation also show that the decrease in the Indian summer monsoon rainfall during ENSO phases is associated with a descending motion of anomalous Walker circulation and the increase in the Indian summer monsoon rainfall during IOD phase is associated with the ascending branch of anomalous regional Hadley circulation. During co-existing ENSO and IOD years, however, the fate of Indian summer monsoon is dictated by the combined influence of both of them. The shift in the anomalous descending and ascending branches of the Walker and Hadley circulation may be somewhat attributed to the cold (warm) bias over eastern (western) equatorial Indian Ocean basin, respectively in the model. This study will be useful for identifying some of the limitations of the CFS model and consequently it will be helpful in improving the model to unravel the realistic coupled ocean–atmosphere interactions for the better prediction of Indian Summer Monsoon.  相似文献   

Mitigating parameter bias in hydrological modelling due to uncertainty in covariates     

Shahadat Chowdhury  Ashish Sharma   《Journal of Hydrology》2007,340(3-4):197-204

The uncertainty in hydrological model covariates, if ignored, introduces systematic bias in the parameters estimated. We introduce here a method to determine the true value of parameters given uncertainty in model inputs. This method, known as simulation extrapolation (SIMEX) operates on the basis of an empirical relationship between parameters and the level of input noise (or uncertainty). The method starts by generating a series of alternate model inputs by artificially adding white noise in increasing multiples of the known error variance. The resulting parameter sets allow us to formulate an empirical relationship between their values and the level of noise present. SIMEX is based on theory that the trend in alternate parameters can be extrapolated back to the notional error free zone.

We illustrate the strength of SIMEX in improving skills of predictive models that use uncertain sea surface temperature anomaly (SSTA) data over the NINO3 region as predictor to the southern oscillation index (SOI), an alternate measure of the strength of the El Nino southern oscillation. Our hypothesis is that the higher magnitude of noise in the pre 1960 data period introduces bias to model parameters where SSTA is the input variable. The relatively error invariant southern oscillation index (SOI) is regressed over SSTA and calibrated using a subset of the series from 1900 to 1960. We validate the resulting models using the less erroneous 1960–2003 data period. Overall the application of SIMEX is found to reduce the residual predictive errors during the validation period.  相似文献