The December 24, 2006 eruption of Bezymyannyi Volcano,Kamchatka     

N. A. Malik 《Journal of Volcanology and Seismology》2011,5(4):268-277

An explosive eruption occurred on Bezymyannyi Volcano December 24, 2006. The distribution of ashfall deposits over the peninsula was studied. The tephra was investigated for its chemical, mineral, and grain-size composition, its water-soluble complex was studied. About 30 000 tons of water-soluble substances along with 7 million tons of ash entered the environment over an area of over 8000 km². Information is supplied for this eruption from various sources and its geological impact has been estimated. The total volume of erupted pyroclastics was 0.01–0.014 km³, of which 0.004 km³ consisted of ash and 0.006–0.01 km³ were pyroclastic flow deposits.  相似文献   

Adaptive state estimation of groundwater contaminant boundary input flux in a 2-dimensional aquifer     

Muhammad Nauman Malik  Mehdi Murtuza  Iqbal Asif  Bakar Muhammad Saifullah Abu  Brahim Aissa  Dk Nur Afiqah Jalwati Puteri  Amer Farhan Rafique 《地下水科学与工程》2014,7(4):373-382

In many circumstances involving heat and mass transfer issues, it is considered impractical to measure the input flux and the resulting state distribution in the domain. Therefore, the need to develop techniques to provide solutions for such problems and estimate the inverse mass flux becomes imperative. Adaptive state estimator (ASE) is increasingly becoming a popular inverse estimation technique which resolves inverse problems by incorporating the semi-Markovian concept into a Bayesian estimation technique, thereby developing an inverse input and state estimator consisting of a bank of parallel adaptively weighted Kalman filters. The ASE is particularly designed for a system that encompasses independent unknowns and /or random switching of input and measurement biases. The present study describes the scheme to estimate the groundwater input contaminant flux and its transient distribution in a conjectural two-dimensional aquifer by means of ASE, which in particular is because of its unique ability to efficiently handle the process noise giving an estimation of keeping the relative error range within 10% in 2-dimensional problems. Numerical simulation results show that the proposed estimator presents decent estimation performance for both smoothly and abruptly varying input flux scenarios. Results also show that ASE enjoys a better estimation performance than its competitor, Recursive Least Square Estimator (RLSE) due to its larger error tolerance in greater process noise regimes. ASE’s inherent deficiency of being slower than the RLSE, resulting from the complexity of algorithm, was also noticed. The chosen input scenarios are tested to calculate the effect of input area and both estimators show improved results with an increase in input flux area especially as sensors are moved closer to the assumed input location.  相似文献   

Temperature-Dependent Dynamics of Confinement     

Raman Kumar Jha  G.P. Malik  Vijaya S. Varma 《Astrophysics and Space Science》1997,249(1):151-159

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Supply-chain impacts of Sichuan earthquake: a case study using disaster input–output analysis     

Huang  Rui  Malik  Arunima  Lenzen  Manfred  Jin  Yutong  Wang  Yafei  Faturay  Futu  Zhu  Zhiyi 《Natural Hazards》2022,110(3):2227-2248

Natural Hazards - With the development of interregional trade, a potential disaster that happens in one place could cause enormous economic losses in distant areas. Timely and comprehensive...  相似文献   

Artificial Neural Networks in Proglacial Discharge Simulation: Application and Efficiency Analysis in Comparison to the Multivariate Regression; A Case Study of Waldemar River (Svalbard)          下载免费PDF全文

Marcin Nowak  Ireneusz Sobota 《Geografiska Annaler: Series A, Physical Geography》2015,97(3):489-506

Artificial neural networks were applied to simulate runoff from the glacierized part of the Waldemar River catchment (Svalbard) based on hydrometeorological data collected in the summer seasons of 2010, 2011 and 2012. Continuous discharge monitoring was performed at about 1 km from the glacier snout, in the place where the river leaves the marginal zone. Averaged daily values of discharge and selected meteorological variables in a number of combinations were used to create several models based on the feed‐forward multilayer perceptron architecture. Due to specific conditions of melt water storing and releasing, two groups of models were established: the first is based on meteorological inputs only, while second includes the preceding day's mean discharge. Analysis of the multilayer perceptron simulation performance was done in comparison to the other black‐box model type, a multivariate regression method based on the following efficiency criteria: coefficient of determination (R²) and its adjusted form (adj. R²), weighted coefficient of determination (wR²), Nash–Sutcliffe coefficient of efficiency, mean absolute error, and error analysis. Moreover, the predictors' importance analysis for both multilayer perceptron and multivariate regression models was done. The performed study showed that the nonlinear estimation realized by the multilayer perceptron gives more accurate results than the multivariate regression approach in both groups of models.  相似文献   

Some aspects of an explanation of the soft x-ray solar emission lines on the basis of a finite-temperature schrödinger equation     

G. P. Malik  Usha Malik  Vijaya S. Varma 《Astrophysics and Space Science》1993,199(2):299-315

We discuss the range of validity of solutions of the Schrödinger equation with a temperaturemodified Coulomb potential. Such a potential, as was recently pointed out, may be relevant to the resolution of the long-standing problem of unidentified solar emission lines. We also consider in detail a predictive test of our approach, and draw attention to some related conceptual issues.  相似文献   

Spatio-temporal trend analysis of rainfall using parametric and non-parametric tests: case study in Uttarakhand,India     

Malik  Anurag  Kumar  Anil 《Theoretical and Applied Climatology》2020,140(1):183-207

Theoretical and Applied Climatology - This study investigates the spatial and temporal patterns of trends and magnitude of rainfall on monthly, seasonal and annual time scales of 13 districts of...  相似文献   

Nonlinear dispersive waves on the surface of a self-gravitating fluid layer     

S. K. Malik  M. Singh 《Astrophysics and Space Science》1981,76(1):3-12

The evolution of two dimensional wave packets on the surface of a self-gravitating fluid layer is investigated and shown to be governed by a nonlinear Schrödinger equation. The wave train of finite amplitude is modulationally unstable. Obtained also are the dynamical equations for the second harmonic resonance. The analysis reveals that the general motion consists of both amplitude and phase modulated waves of which the pure phase and amplitude modulated waves, solitary waves, and phase jump are just the special cases.  相似文献   

Quantitative seafloor characterization using a bathymetric sidescansonar     

Stewart  W.I. Chu  D. Malik  S. Lerner  S. Singh  H. 《Oceanic Engineering, IEEE Journal of》1994,19(4):599-610

Bathymetry and backscatter measurements from a 120-kHz phase-difference sonar are analysed in terms of statistical and spectral characteristics. Data from a multisensor, multiscale survey of the Juan de Fuca Ridge are compared across three distinct geological provinces: sediment pond, ridge flank, and axial valley. The detrended bathymetry follows a Gaussian distribution; the power spectral density can be approximately described by a power law. The composite multiscale power spectrum demonstrates a similar slope spanning a spatial frequency range from about 0.005 to 50 cycles/m, corresponding to a range of geological features from a few hundred meters down to several centimeters. The backscattering strength and grazing-angle dependencies agree with previous empirical studies; data from a sediment-pond region are shown to match theoretical predictions of the composite-roughness model. Histograms of the echo amplitude are characterized by a multimodal Rayleigh probability density function. For all analyses, the data show distinct differences among the three provinces  相似文献   

On KdV solitons in electrohydrodynamics     

Iant  R.  Malik  S. K. 《Astrophysics and Space Science》1983,97(1):205-212

Relativistic flows both in stellar interior and stellar atmospheres are obviously in action, hence, their treatment is of interest. The present communication aims at deriving by a different method the general equations that govern such flows.The derivation is based merely on the first two principles of thermodynamics and the inertia-energy equivalence principles; while the end results are the formulation of the energy tensor and the energy-flux and momentum equations. The assumptions of ideal flow and adiabatic behaviour of the medium adopted here are restrictive.  相似文献