1,967 research outputs found
Information and voting power in the proxy process
We document shareholder support for wealth-decreasing changes in corporate governance in the form of antitakeover charter amendments. the enactment of these amendments is shown to be related to ownership structure. This gives rise to a sample selection bias that contaminates traditional event-study results and explains the discrepancy between our findings and those reported in previous studies. We also provide evidence that strategic behavior by managers plays a role in the adoption of these amendments.Stockholders ; Consolidation and merger of corporations
EFFECT OF CHEMICAL NON-EQUILIBRIUM ON FLOW PARAMETERS IN THE INTERMEDIATE HYPERSONIC REGIME
The new solver hypersonicIithFoam has been developed in
the OpenFOAM framework. OpenFOAM has rhoCentralFoam
which is a density based N-S solver, is used as a base solver.
Additional features are incorporated to model reacting flows,
variable multi-species diffusion and thermodynamic proper-
ties of high-temperature air. The solver is implemented to
model the transport properties based on a kinetic theory for its
widespread applicability. Viscosity and Thermal conductivity are
obtained using the model based on Lennard-Jones potential, and
Chapman-Enskog diffusivity model is used to compute binary dif-
fusion coefficient. Multicomponent mixture properties are calcu-
lated based on a mole fraction. All species are assumed to be in
thermodynamic equilibrium, so the state of the gas is governed
by single equilibrium temperature. The solver is tested with the
available experimental data for Heat flux and coefficient of pres-
sure Cp distribution over a surface of ELECTRE article. The hy-
personic solver is shown significant improvement over a conven-
tional compressible solver. Simulations are carried out for the
flow over a sphere at different altitudes using both the conven-
tional and the hypersonic solver for qualitative and quantitative
comparisons. Post shock temperature and peak heat flux values
are remarkably reduces due to the implementation of real gas ef-
fects and air chemistry. Rarefaction effects become significant
from 70 km
Numerical Analysis of Rarefied Hypersonic and Chemically Reacting Flow-field
We have developed an open source CFD tool, which can
simulate high temperature and chemically reacting flow-field
in the rarefied regime. It is used to carry out simulations in the
intermediate hypersonic flow regime (Mach number range from
8 to 15). Solver is tested with available data for high speed and
rarefied flow applications. Heat load values for blunt conical
surface and shock standoff distance for sphere are obtained
with our solver and good agreement has been exhibited with
the experimental data
Computational Analysis of Side Jet Interaction With a Super-sonic Cross-flow
We have numerically investigated the interaction of a side jet
positioned on the small rocket, with the supersonic cross-flow.
An open source CFD tool, OpenFOAM is used to model the
complex flow of a jet-atmosphere interaction. The flow fields
are computed by the steady 3-dimensional Navier-Stokes solver
with k- ! SST turbulence model. Our solver is validated with
the experimental pressure data available on the rocket wall and
a systematic study is done by varying parameters like jet pressure
ratio. Aerothermodynamic coefficients for various flow
conditions are reported, and pitching moments and normal
forces are found to vary linearly with the jet pressure ratios.
Possible contamination of the on-board sensor located on the
rocket wall due to impinging plumes is also examined. This
study helps in designing effective missile control by selection
of the location of jet and pressure ratios
Green's Matrix for a Second Order Self-Adjoint Matrix Differential Operator
A systematic construction of the Green's matrix for a second order,
self-adjoint matrix differential operator from the linearly independent
solutions of the corresponding homogeneous differential equation set is carried
out. We follow the general approach of extracting the Green's matrix from the
Green's matrix of the corresponding first order system. This construction is
required in the cases where the differential equation set cannot be turned to
an algebraic equation set via transform techniques.Comment: 19 page
LNA for UWB transceiver using 0.18µm CMOS Technology
An Ultra WideBand CMOS Low Noise Amplifier (LNA) is presented. Due to really low power consumption and extremely high data rates the UWB standard is bound to be popular in the consumer market. The LNA is the outer most part of an UWB transceiver. The LNA is responsible for providing enough gain to the signal with the least distortion possible. CMOS 0.18µm TSMC technology has been chosen for the design of the LNA at the transistor level. As many as five on chip inductors are implemented for the proper gain shaping over the frequency range of 3.1GHz to 10.6GHz. A noise figure of 3.98 dB is achieved to make sure noise contribution of the amplifier is as low as possible
Experimental investigations on forming limit diagram of ultra thin SS 304 steel : effect of circular grid size, sheet orientation, punch size and deformation speed
In the present work, SS 304 sheet of 200 μm thickness was used to experimentally evaluate the forming limit diagram (FLD). In this context, a sub-size limiting dome height (LDH) test setup was developed to deform rectangular specimens of different widths using a 30 mm hemispherical punch. Further, effect of various parameters such as change in circular grid size, stretching direction with respect to rolling direction of the sheet, punch size and deformation speed on limiting strains was investigated. It was observed that there was marginal change in limiting strains due to the change of punch diameter from 30 mm to 50 mm. The FLD0 level changed approximately 7.5% and 6.8% with the change in punch diameter and stretching direction respectively. It was also found that the FLD0 value increased by 15% with change in circular grid diameter from 2.5 mm to 2.0 mm. However, a negligible change in the limiting strains was noted when the grid diameter was further reduced to 1.0 mm. There was negligible change in the FLD0 level with increase in punch speed from 4 mm/min to 100 mm/min, but approximately 13% decrease was found when the punch speed was further increased to 400 mm/min. Moreover, the LDH, strain distribution and failure strains were also analyzed in context of formability
Two Dimensional Pseudo-Wiener Filtering in Ultrasonic Imaging for Nondestructive Evaluation Applications
This paper deals with the use of a two dimensional pseudo-Wiener filter for ultrasonic image enhancement. Experimental results are presented to demonstrate the effectiveness of the technique for the improvement of the lateral resolution and image enhancement of ultrasonic images in materials such as graphite/epoxy composites and stainless steel. The difficulties encountered in the implementation of the filter will be delineated. Methods of overcoming some of these ‘implementational hurdles’ will be suggested
Indolent Small Intestinal CD4+ T-cell Lymphoma Is a Distinct Entity with Unique Biologic and Clinical Features
Enteropathy-associated T-cell lymphomas (EATL) are rare and generally aggressive types of peripheral T-cell lymphomas. Rare cases of primary, small intestinal CD4+ T-cell lymphomas with indolent behavior have been described, but are not well characterized. We describe morphologic, phenotypic, genomic and clinical features of 3 cases of indolent primary small intestinal CD4+ T-cell lymphomas. All patients presented with diarrhea and weight loss and were diagnosed with celiac disease refractory to a gluten free diet at referring institutions. Small intestinal biopsies showed crypt hyperplasia, villous atrophy and a dense lamina propria infiltrate of small-sized CD4+ T-cells often with CD7 downregulation or loss. Gastric and colonic involvement was also detected (n = 2 each). Persistent, clonal TCRβ gene rearrangement products were detected at multiple sites. SNP array analysis showed relative genomic stability, early in disease course, and non-recurrent genetic abnormalities, but complex changes were seen at disease transformation (n = 1). Two patients are alive with persistent disease (4.6 and 2.5 years post-diagnosis), despite immunomodulatory therapy; one died due to bowel perforation related to large cell transformation 11 years post-diagnosis. Unique pathobiologic features warrant designation of indolent small intestinal CD4+ T-cell lymphoma as a distinct entity, greater awareness of which would avoid misdiagnosis as EATL or an inflammatory disorder, especially celiac disease
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