Downwind non-uniform mixing in shoreline fumigation processes   总被引：1，自引：0，他引：1  

M. Stunder  S. Sethuraman  P. K. Misra  H. Sahota 《Boundary-Layer Meteorology》1986,34(1-2):177-184

The assumption of vertical uniform mixing in shoreline fumigation models is tested using two types of modifications to a base statistical model that takes into account non-uniform mixing. One of the modifications involves the use of a downdraft velocity scheme developed for a convective boundary layer. The other modification is based on an empirical adjustment factor derived from water tank experiments. Results from all three models are compared with field observations. Comparisons indicate that the modifications do not improve the results of the base dispersion model.  相似文献   

The effects of mesoscale turbulence on plume rise in a land/lake environment     

G. C. Edwards  P. K. Misra 《Boundary-Layer Meteorology》1984,29(2):155-165

An extensive data base of LIDAR and photographically measured plumes from the Nanticoke thermal generating station (located on the north shore of Lake Erie) has been accumulated over several years of full-scale atmospheric experiments. Analysis of the data shows that the empirical entrainment constant used in the Briggs simple plume rise formulation has a value of 0.8, which is significantly larger than 0.6 found by Briggs (1975). A hypothesis is proposed that mesoscale eddies present in the land/lake environment are responsible for vertical plume meander leading to the observed enhanced vertical plume spread and lower mean plume rise at this site. This is substantiated through theoretical considerations and experimental data. The results are significant in the computation of ground-level concentrations at such complex terrain sites.  相似文献   

Depositional environment of the Krol Group of the Nainital area and its impact on the stromatolites     

S. B. Misra 《Journal of Earth System Science》1984,93(4):447-464

Depositional environment of the Krol group varied temporally from subtidal in the Manora to intertidal in the Sleepy Hollow times. The conditions that succeeded were peritidal in the Ayarpatta and supratidal in the Narainnagar times. These conditions were the main controlling factors in the growth and development of the algal stromatolites. The Manora formation, due to subtidal conditions, and the Sleepy Hollow formation, due to detrital influx, are almost devoid of stromatolites. The carbonates of the Ayarpatta formation representing a peritidal complex possess columnar and oncolitic stromatolites, while the sediments of the Narainnagar formation characterized by supratidal features contain blistered, domal and crinkled-laminar forms. The types and sizes of stromatolites therefore are governed by the depositional conditions prevailing in the sedimentary basin.  相似文献   

Stable (δ13C and δ15N) isotopes and magnetic susceptibility record of late Holocene climate change from a lake profile of the northeast Himalaya     

Shailesh Agrawal  Pradeep Srivastava  Sonam  N. K. Meena  Santosh K. Rai  R. Bhushan  D. K. Misra  A. K. Gupta 《Journal of the Geological Society of India》2015,86(6):696-705

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Effect of the finite size of an asteroid on its deflection using a tether–ballast system     

Mohammad J. Mashayekhi  Arun K. Misra 《Celestial Mechanics and Dynamical Astronomy》2016,125(3):363-380

Potentially hazardous near-Earth objects which can impose a significant threat on life on the planet have generated a lot of interest in the study of various asteroid deflection strategies. There are numerous asteroid deflection techniques suggested and discussed in the literature. This paper is focused on one of the non-destructive asteroid deflection strategies by attaching a long tether–ballast system to the asteroid. In the existing literature on this technique, very simplified models of the asteroid-tether–ballast system including a point mass model of the asteroid have been used. In this paper, the dynamical effect of using a finite size asteroid model on the asteroid deflection achieved is analyzed in detail. It has been shown that considering the finite size of the asteroid, instead of the point mass approximation, can have significant influence on the deflection predicted. Furthermore the effect of the tether-deployment stage, which is an essential part of any realistic asteroid deflection mission, on the predicted deflection is studied in this paper. Finally the effect of cutting the tether on the deflection achieved is analyzed and it has been shown that depending on the orbital properties of the asteroid as well as its size and rotational rate, cutting the tether at an appropriate time can increase the deflection achieved. Several numerical examples have been used in this paper to elaborate on the proposed technique and to quantitatively analyze the effect of different parameters on the asteroid deflection.  相似文献   

Lunar tidal oscillations in the horizontal ionospheric drift at the equator     

R.K. Misra 《Planetary and Space Science》1973,21(7):1109-1114

The effect of lunar tides on the apparent ionospheric drift velocity (V) for an equatorial station Thumba (0.6°S dip) is computed by using nearly six years of data at fixed solar hours. Significant tides are observed in the E-region drifts, particularly around 12.00 hr and in the F-region drifts around 15.00 hr.A good correlation in the phases of the lunar tides in H and V is found to exist, suggesting a strong electrojet control of the horizontal ionospheric drift around these hours.  相似文献   

A multivariate analysis of morphometrics to detect differences in populations of capelin (Mallotus villosus)     

Misra  R. K.; Carscadden  J. E. 《ICES Journal of Marine Science》1987,43(2):99-106

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An Objective Analysis of Support Vector Machine Based Classification for Remote Sensing     

Thomas Oommen  Debasmita Misra  Navin K. C. Twarakavi  Anupma Prakash  Bhaskar Sahoo  Sukumar Bandopadhyay 《Mathematical Geosciences》2008,40(4):409-424

Accurate thematic classification is one of the most commonly desired outputs from remote sensing images. Recent research efforts to improve the reliability and accuracy of image classification have led to the introduction of the Support Vector Classification (SVC) scheme. SVC is a new generation of supervised learning method based on the principle of statistical learning theory, which is designed to decrease uncertainty in the model structure and the fitness of data. We have presented a comparative analysis of SVC with the Maximum Likelihood Classification (MLC) method, which is the most popular conventional supervised classification technique. SVC is an optimization technique in which the classification accuracy heavily relies on identifying the optimal parameters. Using a case study, we verify a method to obtain these optimal parameters such that SVC can be applied efficiently. We use multispectral and hyperspectral images to develop thematic classes of known lithologic units in order to compare the classification accuracy of both the methods. We have varied the training to testing data proportions to assess the relative robustness and the optimal training sample requirement of both the methods to achieve comparable levels of accuracy. The results of our study illustrated that SVC improved the classification accuracy, was robust and did not suffer from dimensionality issues such as the Hughes Effect.  相似文献   

Local onset and demise of the Indian summer monsoon     

Misra  Vasubandhu  Bhardwaj  Amit  Mishra  Akhilesh 《Climate Dynamics》2018,51(5-6):1609-1622

This paper introduces an objective definition of local onset and demise of the Indian summer monsoon (ISM) at the native grid of the Indian Meteorological Department’s rainfall analysis based on more than 100 years of rain gauge observations. The variability of the local onset/demise of the ISM is shown to be closely associated with the All India averaged rainfall onset/demise. This association is consistent with the corresponding evolution of the slow large-scale reversals of upper air and ocean variables that raise the hope of predictability of local onset and demise of the ISM. The local onset/demise of the ISM also show robust internannual variations associated with El Nino and the Southern Oscillation and Indian Ocean dipole mode. It is also shown that the early monsoon rains over northeast India has a predictive potential for the following seasonal anomalies of rainfall and seasonal length of the monsoon over rest of India.

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Micromechanical model of rough contact between rock blocks with application to wave propagation     

Anil Misra  Orestes Marangos 《Acta Geophysica》2008,56(4):1109-1128

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