Compact-Reconstruction Weighted Essentially Non-Oscillatory Schemes for Hyperbolic Conservation Laws

A new class of non-linear compact interpolation schemes is introduced in this dissertation that have a high spectral resolution and are non-oscillatory across discontinuities. The Compact-Reconstruction Weighted Essentially Non-Oscillatory (CRWENO) schemes use a solution-dependent combination of lower-order compact schemes to yield a high-order accurate, non-oscillatory scheme. Fifth-order accurate CRWENO schemes are constructed and their numerical properties are analyzed. These schemes have lower absolute errors and higher spectral resolution than the WENO scheme of the same order. The schemes are applied to scalar conservation laws and the Euler equations of fluid dynamics. The order of convergence and the higher accuracy of the CRWENO schemes are verified for smooth solutions. Significant improvements are observed in the resolution of discontinuities and extrema as well as the preservation of flow features over large convection distances. The computational cost of the CRWENO schemes is assessed and the reduced error in the solution outweighs the additional expense of the implicit scheme, thus resulting in higher numerical efficiency. This conclusion extends to the reconstruction of conserved and primitive variables for the Euler equations, but not to the characteristic-based reconstruction. Further improvements are observed in the accuracy and resolution of the schemes with alternative formulations for the non-linear weights. The CRWENO schemes are integrated into a structured, finite-volume Navier-Stokes solver and applied to problems of practical relevance. Steady and unsteady flows around airfoils are solved to validate the scheme for curvi-linear grids, as well as overset grids with relative motion. The steady flow around a three-dimensional wing and the unsteady flow around a full-scale rotor are solved. It is observed that though lower-order schemes suffice for the accurate prediction of aerodynamic forces, the CRWENO scheme yields improved resolution of near-blade and wake flow features, including boundary and shear layers, and shed vortices. The high spectral resolution, coupled with the non-oscillatory behavior, indicate their suitability for the direct numerical simulation of compressible turbulent flows. Canonical flow problems -- the decay of isotropic turbulence and the shock-turbulence interaction -- are solved. The CRWENO schemes show an improved resolution of the higher wavenumbers and the small-length-scale flow features that are characteristic of turbulent flows. Overall, the CRWENO schemes show significant improvements in resolving and preserving flow features over a large range of length scales due to the higher spectral resolution and lower dissipation and dispersion errors, compared to the WENO schemes. Thus, these schemes are a viable alternative for the numerical simulation of compressible, turbulent flows

Do NBFCs Propagate Real Shocks?

In this paper, we try to explain the role of Non-bank Financial Intermediation (NBFI) to percolate and propel a real shock to the rest of the economy through the bank-NBFI interactions. We propose a simple theoretical model which identifies the channels and distinguishes between idiosyncratic, structural and sectoral shocks, cleanly. In our model, the non-deposit taking Non-bank Financial companies (NBFCs) which are the provider of risky, small and fragmented loans, are financed by borrowing from commercial banks. This link connects the NBFCs with the commercial banks and, in turn, with the rest of the economy. A higher realization of the failed firms (idiosyncratic shock) in the NBFC financed sector and a rise in the sector-wide productivity risk (sectoral risk) increase the interest rate charged by the banks and unemployment rate but reduces the real wages and per capita capital formation of the economy. However, when the average number of failed firms increases (structural shock), the reverse happens

Burkitt's Lymphoma as Primary Adrenal Lymphoma Diagnosed on Fine Needle Aspiration Cytology : A Rare Case Report

Introduction :Primary adrenal lymphoma presenting as Burkitt’s lymphoma  is an extremely rare entity. Although biopsy or excision is often needed for definitive diagnosis computed tomography guided fine needle aspiration has great diagnostic value in detection of primary adrenal lymphoma.Presentation of case : A case  of a 20 yr old male with a right adrenal mass diagnosed as Burkitts lymphoma on Fine Needle Aspiration Cytology (confirmed by bone marrow and cytogenetics) has been reported.Conclusion : Fine Needle Aspiration Cytology  as an initial investigation tool can be very effective for detection of unusual presentation like an adrenal mass in a case of Burkitt's lymphom

The asymmetric impact of oil price uncertainty on emerging market financial stress : A quantile regression approach

This study investigates the effects of the crude oil implied volatility index (OVX) upon emerging market financial stress (EMFS). We resort to a quantile regression framework as this approach is a better alternative to disentangle the relationship under different market conditions. Besides, we also examine how EMFS responds to the lags and asymmetries in the OVX. The empirical results show significantly positive impacts of OVX upon EMFS. Further, the effects of OVX become more assertive in the upper quantiles of EMFS, implying higher sensitivity to OVX when stress levels are high. In terms of the lagged effects, the relationship is transient as the OVX coefficients become weaker with increasing lag sizes. We further find that only positive impulses in OVX can significantly predict EMFS. Lastly, we report evidence that the Credit market stress is a crucial driver of EMFS.© 2022 The Authors. International Journal of Finance & Economics published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution-Non Commercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.fi=vertaisarvioitu|en=peerReviewed

High-order Discretization of a Gyrokinetic Vlasov Model in Edge Plasma Geometry

We present a high-order spatial discretization of a continuum gyrokinetic Vlasov model in axisymmetric tokamak edge plasma geometries. Such models describe the phase space advection of plasma species distribution functions in the absence of collisions. The gyrokinetic model is posed in a four-dimensional phase space, upon which a grid is imposed when discretized. To mitigate the computational cost associated with high-dimensional grids, we employ a high-order discretization to reduce the grid size needed to achieve a given level of accuracy relative to lower-order methods. Strong anisotropy induced by the magnetic field motivates the use of mapped coordinate grids aligned with magnetic flux surfaces. The natural partitioning of the edge geometry by the separatrix between the closed and open field line regions leads to the consideration of multiple mapped blocks, in what is known as a mapped multiblock (MMB) approach. We describe the specialization of a more general formalism that we have developed for the construction of high-order, finite-volume discretizations on MMB grids, yielding the accurate evaluation of the gyrokinetic Vlasov operator, the metric factors resulting from the MMB coordinate mappings, and the interaction of blocks at adjacent boundaries. Our conservative formulation of the gyrokinetic Vlasov model incorporates the fact that the phase space velocity has zero divergence, which must be preserved discretely to avoid truncation error accumulation. We describe an approach for the discrete evaluation of the gyrokinetic phase space velocity that preserves the divergence-free property to machine precision

Impact of COVID-19 shock on a segmented labour market: Analysis using a unique panel dataset

This paper studies the impact of economic crisis caused by the COVID on the Indian labour market using the Periodic Labour Force Survey (PLFS). The unique dataset offers the opportunity to analyse sectoral transition and mobility of workers in response to a crisis due to its rotational panel framework. We employ transition matrices, non-parametric cumulative distribution functions, and machine learning techniques to identify the impact of COVID shock on formal and informal sector workers and whether this impact was heterogeneous. We find that labour market outcomes, both in terms of employment status and income, became even more divergent between the formal and informal sectors during the first wave of pandemic and remained divergent in the recovery phase. The classification analysis highlights that the sector in which the worker was employed (formal or informal sector), was an important predictor of income loss during the first wave

Diversity and Distribution of Archaea in the Mangrove Sediment of Sundarbans

Mangroves are among the most diverse and productive coastal ecosystems in the tropical and subtropical regions. Environmental conditions particular to this biome make mangroves hotspots for microbial diversity, and the resident microbial communities play essential roles in maintenance of the ecosystem. Recently, there has been increasing interest to understand the composition and contribution of microorganisms in mangroves. In the present study, we have analyzed the diversity and distribution of archaea in the tropical mangrove sediments of Sundarbans using 16S rRNA gene amplicon sequencing. The extraction of DNA from sediment samples and the direct application of 16S rRNA gene amplicon sequencing resulted in approximately 142 Mb of data from three distinct mangrove areas (Godkhali, Bonnie camp, and Dhulibhashani). The taxonomic analysis revealed the dominance of phyla Euryarchaeota and Thaumarchaeota (Marine Group I) within our dataset. The distribution of different archaeal taxa and respective statistical analysis (SIMPER, NMDS) revealed a clear community shift along the sampling stations. The sampling stations (Godkhali and Bonnie camp) with history of higher hydrocarbon/oil pollution showed different archaeal community pattern (dominated by haloarchaea) compared to station (Dhulibhashani) with nearly pristine environment (dominated by methanogens). It is indicated that sediment archaeal community patterns were influenced by environmental conditions