1,709 research outputs found
Optimal Banking Sector Recapitalization
Government-financed bank restructuring programs, occasionally costing up to 50% of GDP, are commonly used to resolve banking crises. We analyze the Ramsey-optimal paths of bank recapitalization programs that weigh recapitalization benefits and costs under different financing options. In our model bank credit is essential, due to a working capital constraint on firms, and banks are financial intermediaries that borrow from households and lend to firms. A banking crisis produces a disruption of credit and a fall in output equivalent to those in developing countries affected by banking crises. Full recapitalization of the banking system immediately after the crisis is optimal only if international credit is available. One-shot recapitalization is not optimal with domestically-financed programs, even if the government has access to non-distortionary taxes. The welfare cost of a crisis is substantial: the equivalent permanent decline in the no-crisis steady state consumption ranges between 0.51% and 0.65%, depending on the source of financing the recapitalization program.financial intermediation; bank recapitalization; banking crises; banking capital
Unified Mechanical Erosion Model for Multi-phase Mass Flows
Erosion poses a great challenge in multi-phase mass flows as it drastically
changes flow behavior and deposition pattern by dramatically increasing their
masses, adversely affecting population and civil structures. There exists no
mechanically-explained, unified multi-phase erosion model. We constitute a
novel, unified and comprehensive mechanical erosion rates for solid and fluid
phases and demonstrate their richness and urgency. This is achieved by
seminally introducing interacting stresses across erosion-interface. Shear
resistances from the bed against shear stresses from the landslide are based on
consistent physical principles. Proposed multi-phase interactive shear
structures are mechanically superior and dynamically flexible. Total erosion
rate is the sum of solid and fluid erosion rates which are mechanically
extensive and compact. Erosion rates consistently take solid and fluid
fractions from the bed and customarily supply to solid and fluid components in
the flow. This overcomes severe limitations inherited by existing models. For
the first time, we physically correctly construct composite, intricate erosion
velocities of particle and fluid from the bed and architect the complete net
momentum productions that include all interactions between solids and fluids in
the landslide and bed. We invent stress correction, erosive-shear-velocity,
super-erosion-drift and erosion-matrix characterizing complex erosion
processes. By embedding well constrained extensive erosion velocities, unified
erosion rates and net momentum productions including erosion-induced inertia
into mass and momentum balances, we develop a novel, mechanically-explained,
comprehensive multi-phase model for erosive mass flows. As new model covers a
broad spectrum of natural processes it offers great opportunities for
practitioners in solving technical, engineering problems related to erosive
multi-phase mass flows
Extended landslide velocity and analytical drag
The landslide velocity plays a dominant role in estimating impact force and
devastated area. Here, based on Pudasaini and Krautblatter (2022), I develop a
novel extended landslide velocity model that includes the force induced by the
hydraulic pressure gradient which was neglected by all the existing analytical
landslide velocity models. By a rigorous conversion between this force and
inertia, I develop two peer systems expecting to produce the same results.
However, this contradicts with our conventional wisdom. This raises a question
of whether we should develop some new balance equations. I compare the two
velocity models that neglects and includes the force induced by the hydraulic
pressure gradient. Analytical solutions produced by the two systems are
different. The new model is comprehensive, elegant, and yet an extraordinary
development as it reveals serendipitous circumstances resulting in a
pressure-inertia-paradox. Surprisingly, the mass first moves upstream, then it
winds back and accelerates downslope. The difference between the extended and
simple solution widens strongly as the force associated with the hydraulic
pressure gradient increases, demonstrating its importance. Viscous drag plays
an important role in controlling the landslide dynamics. However, no explicit
mechanical and analytical model exists for this. The careful sagacity of the
graceful form of new velocity equation results in a mechanically extensive,
dynamically evolving analytical model for viscous drag, the first of this kind.
A dimensionless drag number is constructed. Contrary to the prevailing
practices, I have proven that drags are essentially different for the expanding
and contracting motions, an entirely novel perception. Drag coefficients are
close to the often used empirical or numerical values. But, now, I offer an
innovative, physically-founded analytical model for drag in mass flow
simulation
Superconductivity at 5K in NdO0.5F0.5BiS2
We report appearance of superconductivity at 5K in NdO0.5F0.5BiS2 and
supplement the discovery [1] of the same in layered sulfide based ZrCuSiAs type
compounds. The bulk polycrystalline compound is synthesized by conventional
solid state route via vacuum encapsulation technique. Detailed structural
analysis showed that the studied compound is crystallized in tetragonal P4/nmm
space group with lattice parameters a = 3.9911(3) {\AA}, c = 13.3830(2) {\AA}.
Bulk superconductivity is established in NdO0.5F0.5BiS2 at 5K by both transport
and magnetic measurements. Electrical transport measurements showed
superconducting Tc onset at 5.2K and Tc ({\rho}=0) at 4.7K. Under applied
magnetic field both Tc onset and Tc ({\rho} =0) decrease to lower temperatures
and an upper critical field [Hc2(0)] of above 23kOe is estimated. Both AC and
DC magnetic susceptibility measurements showed bulk superconductivity below 5K.
Isothermal magnetization (MH) exhibited typical type II behavior with lower
critical field (Hc1) of around 15Oe. Isothermal magnetization (MH) exhibited
typical type-II behavior with lower critical field (Hc1) of around 15Oe.
Specific heat [Cp(T)] is investigated in the temperature range of 1.9-50K in
zero external magnetic field. A Schottky-type anomaly is observed at low
temperature below 7K. This low temperature Schottky can be attributed to the
change in the entropy of the system.Comment: 10 pages text + Figs (New Version):comments/suggestion welcome
([email protected]
Superconducting Mechanism through direct and redox layer doping in Pnictides
The mechanism of superconductivity in pnictides is discussed through direct
doping in superconducting FeAs and also in charge reservoir REO layers. The
un-doped SmFeAsO is charge neutral SDW (Spin Density Wave) compound with
magnetic ordering below 150 K. The Superconducting FeAs layers are doped with
Co and Ni at Fe site, whereas REO layers are doped with F at O site. The
electron doping in SmFeAsO through Co results in superconductivity with
transition temperature (Tc) maximum up to 15 K, whereas F doping results in Tc
upto 47 K in SmFeAsO. All these REFe/Co/NiAsO/F compounds are iso-structural to
ZrCuSiAs structure. The samples are crystallized in a tetragonal structure with
space group P4/nmm. Variation of Tc with different doping routes shows the
versatility of the structure and mechanism of occurrence of superconductivity.
It seems doping in redox layer is more effective than direct doping in
superconducting FeAs layer.Comment: 4 Pages text + Figs: ([email protected]
Synthesis and superconductivity of new BiS2 based superconductor PrO0.5F0.5BiS2
We report synthesis and superconductivity at 3.7K in PrO0.5F0.5BiS2. The
newly discovered material belongs to the layered sulfide based REO0.5F0.5BiS2
compounds having ZrCuSiAs type structure. The bulk polycrystalline compound is
synthesized by vacuum encapsulation technique at 7800C in single step. Detailed
structural analysis has shown that the as synthesized PrO0.5F0.5BiS2 is
crystallized in tetragonal P4/nmm space group with lattice parameters a =
4.015(5) {\AA}, c = 13.362(4) {\AA}. Bulk superconductivity is observed in
PrO0.5F0.5BiS2 below 4K from magnetic and transport measurements. Electrical
transport measurements showed superconducting transition temperature (Tc) onset
at 3.7K and Tc ({\rho}=0) at 3.1K. Hump at Tc related to superconducting
transition is not observed in heat capacity measurement and rather a
Schottky-type anomaly is observed at below ~6K. The compound is slightly
semiconducting in normal state. Isothermal magnetization (MH) exhibited typical
type II behavior with lower critical field (Hc1) of around 8Oe.Comment: Short note 10 pages text+figs. First report on PrO.5F.5BiS2 Su
Geometry of Streamlines in Fluid Flow Theory
Intrinsic properties of lines of flow has been studied by employing anholonomic co ordinate system consisting of s-lines which are streamlines, n-lines the involutes of s-lines and b- lines the locus of centre of spherical curvature of s-lines. This gives rise to only two geometric parameters and interesting have been obtained. It was also shown that velocity can be expressed in terms of geometric parameters. Constancy of velocity along binormal line implies existence of Lump surface for the motion. It is found is not irrotational unless it is plane motion. In generalised screw motion it is found that wn/v=constant along the stream line
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