Parameter and quantile estimation of the 2-parameter kappa distribution by maximum likelihood

Asymptotic properties of maximum likelihood parameter and quantile estimators of the 2-parameter kappa distribution are studied. Eight methods for obtaining large sample confidence intervals for the shape parameter and for quantiles of this distribution are proposed and compared by using Monte Carlo simulation. The best method is highlighted on the basis of the coverage probability of the confidence intervals that it produces for sample sizes commonly found in practice. For such sample sizes, confidence intervals for quantiles and for the shape parameter are shown to be more accurate if the quantile estimators are assumed to be log normally distributed rather than normally distributed (same for the shape parameter estimator). Also, confidence intervals based on the observed Fisher information matrix perform slightly better than those based on the expected value of this matrix. A hydrological example is provided in which the obtained theoretical results are applied.     

Simulation of Vortex-Induced Vibrations of A Cylinder Using ANSYS CFX Rigid Body Solver

This article simulates the vortex-induced oscillations of a rigid circular cylinder with elastic support using the new ANSYS CFX rigid body solver. This solver requires no solid mesh to setup FSI (Fluid Structure Interaction) simulation. The two-way case was setup in CFX only. Specific mass of the cylinder and flow conditions were similar to previous experimental data with mass damping parameter equal to 0.04, specific mass of 1 and Reynolds number of 3800. Two dimensional simulations were setup. Both one-degree-of-freedom and two-degree-of-freedom cases were run and results were obtained for both cases with reasonable accuracy as compared with experimental results. Eight-figure XY trajectory and lock-in behavior were clearly captured. The obtained results were satisfactory.     

Analysis and Design of Monopile Foundations for Offshore Wind-Turbine Structures

Offshore wind turbines (OWTs) are generally supported by large-diameter monopiles, with the combination of axial forces, lateral forces, bending moments, and torsional moments generated by the OWT structure and various environmental factors resisted by earth pressures mobilized in the soil foundation. The lateral loading on the monopile foundation is essentially cyclic in nature and typically of low amplitude. This state-of-the-art review paper presents details on the geometric design, nominal size, and structural and environmental loading for existing and planned OWT structures supported by monopile foundations. Pertinent ocean-environment loading conditions, including methods of calculation using site-specific data, are described along with wave particle kinematics, focusing on correlations between the loading frequency and natural vibration frequency of the OWT structure. Existing methods for modeling soil under cyclic loading are reviewed, focusing in particular on strain accumulation models that consider pile–soil interaction under cyclic lateral loading. Inherent limitations/shortcomings of these models for the analysis and design of existing and planned OWT monopile foundations are discussed. A design example of an OWT support structure having a monopile foundation system is presented. Target areas for further research by the wind-energy sector, which would facilitate the development of improved analyses/design methods for offshore monopiles, are identified.     

Monitoring cryosphere and associated flood hazards in high mountain ranges of Pakistan using remote sensing technique

Knowledge of Himalayan cryosphere seems to be an outstanding requirement for assessment of glacier storage, water balance analysis, planning of water resources and flood hazard monitoring. A stepwise approach through mapping glaciers and glacial lakes using satellite remote sensing data and investigating potential glacial lake outburst flood (GLOF) hazards was adopted for the three Hindukush, Karakoram and Himalayan (HKH) ranges of Pakistan. The findings of the study revealed 5,218 glaciers in the cryosphere of HKH ranges. The cumulative glacial cover of over 15,000 km² contains ice reserves of about 2,738 km³. About 46 % of the Karakoram glaciers are contributing 77 % to the total glacial cover and 87 % to the cumulative ice reserves of the country. The 33 % Himalayan glaciers and 21 % Hindukush glaciers contribute only 3 and 10 % ice reserves, respectively. Among 2,420 glacial lakes identified in the three HKH ranges, 52 were classified as critical lakes that can pose GLOF hazard for the downstream communities. Most of the potential hazardous lakes lie in the Karakoram and Himalayan ranges, the monitoring of which is crucial to reduce high risk of future floods hazard in this fragile mountain ecosystem of the Himalayan region.     

Obliquely propagating quasi one dimensional electrostatic solitary structures in dense magnetoplasmas with trapped electrons

In the present investigation, we have studied the linear and nonlinear propagation of electrostatic waves in a dense magnetoplasma with trapped electrons. Using the small amplitude approximation, formation of solitary structures has been studied both for fully and partially degenerate plasmas. The theoretical results obtained have been analyzed numerically for the parameters typically found in white dwarfs. The present work may be beneficial to understand the propagation of solitary structures with weak transverse perturbation with special reference to white dwarf asteroseismology.     

Ion-acoustic waves in non-Maxwellian magnetospheric electron-positron-ion plasma

Using Boltzmann-Vlasov kinetic model for nonthermal distributed electron-positron-ion plasma of our Earth’s magnetosphere and the solar wind streaming plasma can drive ion-acoustic waves unstable. It is found that the growth rate increases with the decrease of spectral index and increases with the streaming velocity of the solar wind. The numerical results are also presented by choosing some suitable parameters of magnetospheric plasma.     

Effects of Land Transformation on Water Quality of Dal Lake,Srinagar, India

The present study focuses on the growing human needs which drive the native boatmen of the Kashmir valley (Hanjis) that bring the interchanges of land use/cover classes in Dal lake and its environs of Srinagar city. Further to assesses the effects of land transformation on lake water quality. The results suggested that the significant land use changes have been occurred during the past of 30 years (1981–2011). Besides this, interchange of land has taken place between different land uses classes, which has resulted into lake water pollution due the addition of various nutrients/pollutant discharged from Hanjis activities. The study concludes that the land transformation has converted the once fresh water lake much deteriorated pond.     

Sheared ion flow driven nonlinear coherent structures in inhomogeneous electron-positron-ion quantum magnetoplasmas

Nonlinear equations governing the dynamics of finite amplitude drift-acoustic-waves are derived by taking into account sheared ion flow perpendicular to the ambient magnetic field in a quantum magnetoplasma comprised of electrons, positrons, and ions. It is shown that stationary solution of the nonlinear equations can be represented in the form of a counter-rotating vortex for a particular choice of the equilibrium profile. The counter rotating vortices are, however, observed to form on very short scales i.e., of the order of ion Larmor radius ρ _i in quantum plasmas. It is observed that the scalelengths over which these structures form get modified in the presence of quantum statistical and Bohm potential terms as well as the positron concentration. The relevance of the present investigation with regard to dense astrophysical environments is also pointed out.     

Constrained iterative ensemble smoother for multi solution search assisted history matching

Computational Geosciences - History matching algorithms usually converge to the most prominent solution in the hypercube of parameter space defined by bound values. Here, we present a workflow to...