728 research outputs found
Appoximation-assisted [sic] estimation of eigenvectors under quadratic loss
Improved estimation of eigen vector of covariance matrix is considered under uncertain
prior information (UPI) regarding the parameter vector. Like statistical models
underlying the statistical inferences to be made, the prior information will be
susceptible to uncertainty and the practitioners may be reluctant to impose the additional
information regarding parameters in the estimation process. A very large
gain in precision may be achieved by judiciously exploiting the information about the
parameters which in practice will be available in any realistic problem.
Several estimators based on preliminary test and the Stein-type shrinkage rules
are constructed. The expressions for the bias and risk of the proposed estimators
are derived and compared with the usual estimators. We demonstrate that how
the classical large sample theory of the conventional estimator can be extended to
shrinkage and preliminary test estimators for the eigenvector of a covariance matrix.
It is established that shrinkage estimators are asymptotically superior to the usual
sample estimators. For illustration purposes, the method is applied to three datasets
Finite elements software and applications
The contents of this thesis are a detailed study of the software
for the finite element method. In the text, the finite element method
is introduced from both the engineering and mathematical points of view.
The computer implementation of the method is explained with samples of
mainframe, mini- and micro-computer implementations. A solution is
presented for the problem of limited stack size for both mini- and
micro-computers which possess stack architecture.
Several finite element programs are presented. Special purpose
programs to solve problems in structural analysis and groundwater flow
are discussed. However, an efficient easy-to-use finite element program
for general two-dimensional problems is presented. Several problems in
groundwater flow are considered that include steady, unsteady flows in
different types of aquifers. Different cases of sinks and sources in
the flow domain are also considered. The performance of finite element
methods is studied for the chosen problems by comparing the numerical
solutions of test problems with analytical solutions (if they exist) or
with solutions obtained by other numerical methods. The polynomial
refinement of the finite elements is studied for the presented problems
in order to offer some evidence as to which finite element simulation
is best to use under a variety of circumstances
Entropy generation for MHD natural convection in enclosure with a micropolar fluid saturated porous medium with Al2O3Cu water hybrid nanofluid
This contribution gives a numerical investigation of buoyancy-driven flow of natural convection heat transfer and entropy generation of non-Newtonian hybrid nanofluid (Al2O3-Cu) within an enclosure square porous cavity. Hybrid nanofluids represent a novel type of enhanced active fluids. During the current theoretical investigation, an actual available empirical data for both thermal conductivity and dynamic viscosity of hybrid nanofluids are applied directly. Numerical simulation have been implemented for solid nanoparticles, the volumetric concentration of which varies from 0.0% (i.e., pure fluid) to 0.1% of hybrid nanofluids. Heat and sink sources are situated on a part of the left and right sides of the cavity with length B, while the upper and bottom horizontal sides are kept adiabatic. The stated partial differential equations describing the flow are mutated to a dimensionless formulas, then solved numerically via the help of an implicit finite difference approach. The acquired computations are given in terms of streamlines, isotherms, isomicrorotations, isoconcentraions, local Began number, total entropy, local and mean Nusselt numbers. The data illustrates that variations of ratio of the average Nusselt number to the average Nusselt of pure fluid Num+ is a decreasing function of Ha and φ, while e+ is an increasing function of Ha and φ parameters of hybrid nanofluid
Novel Green Micro-Synthesis of Graphene-Titanium Dioxide Nano- Composites with Photo-Electrochemical Properties
Background: Graphene-Titanium dioxide nano-composite forms a very promising material in the field of photo-electrochemical research.
Methods: In this study, a novel environment-friendly synthesis method was developed to produce well-distributed anatase nano-titanium dioxide spherical particles on the surface of graphene sheets. This novel method has great advantages over previously developed methods of producing graphenetitanium dioxide nanocomposites (GTNCs). High calcination temperature 650°C was used in the preparation of nano titanium dioxide, and chemical exfoliation for graphene synthesis and GTNC was performed by our novel method of depositing titanium dioxide nanoparticles on graphene sheets using a Y-shaped micro-reactor under a controlled pumping rate with minimal use of chemicals.
Results: The physiochemical and crystallographic properties of the GTNC were confirmed by TEM, XRD, FTIR and EDX measurements, confirming process repeatability. Spherical nano-titanium dioxide was produced in the anatase phase with very high crystallinity and small particle diameters ranging from 9 nm to 25 nm, also the as prepared graphene (RGO) exhibited minimal flake folding and a high carbon content of 81.28% with a low oxygen-to-carbon atomic ratio of 0.172 and GTNCs produced by our novel method had a superior loading content, a homogeneous distribution and a 96.6% higher content of titanium dioxide particles on the graphene sheets compared with GTNCs prepared with the one-pot method.
Conclusion: For its photoelectrochemical properties, chronoamperometry showed that GTNC sample (2) had a higher peak current of 60 μA compared with that of GTNC sample (1), which indicates that the separation and transfer of electron-hole pairs are better in the case of GTNC sample (2) and according to the LSV results, the generation of photocurrent in the samples can be observed through multiple on-off cycles, which indicates that the electrodes are stable and that the photocurrent is quite reversible
Similarity Solution for Unsteady MHD Flow Near a Stagnation Point of a Three-Dimensional Porous Body with Heat and Mass Transfer, Heat Generation/Absorption and Chemical Reaction
The problem of unsteady mixed convection heat and mass transfer near the stagnation point of a three-dimensional
porous body in the presence of magnetic field, chemical reaction and heat source or sink is analyzed. An efficient,
iterative, tri-diagonal implicit finite difference method is used to solve the transformed similarity equations in the
boundary layer. Three cases were considered, namely, accelerating flow, decelerating flow and the steady-state case.
The obtained results are presented in graphical and tabulated forms to illustrate the influence of the different physical
parameters such as the magnetic field parameter, transpiration parameter, unsteadiness parameter, ratio of velocity
gradients at the edge of the boundary layer parameter, heat generation/absorption parameter and the chemical reaction
parameter on the velocity components in the x-and y- directions, temperature and concentration distributions, as well
as the skin-friction coefficients and Nusselt and Sherwood numbers
10 years of livestock policy analysis. Policies for improving productivity, competitiveness and sustainable livelihoods of smallholder livestock producers
Automated grade classification of oral epithelial dysplasia using morphometric analysis of histology images
Oral dysplasia is a pre-malignant stage of oral epithelial carcinomas, e.g., oral squamous cell carcinoma, where significant changes in tissue layers and cells can be observed under the microscope. However, malignancy can be reverted or cured using proper medication or surgery if the grade of malignancy is assessed properly. The assessment of correct grade is therefore critical in patient management as it can change the treatment decisions and prognosis for the dysplastic lesion. This assessment is highly challenging due to considerable inter- and intraobserver variability in pathologists’ agreement, which highlights the need for an automated grading system that can predict more accurate and reliable grade. Recent advancements have made it possible for digital pathology (DP) and artificial intelligence (AI) to join forces from the digitization of tissue slides into images and using those images to train and predict more accurate grades using complex AI models. In this regard, we propose a novel morphometric approach exploiting the architectural features in dysplastic lesions i.e., irregular epithelial stratification where we measure the widths of different layers of the epithelium from the boundary layer i.e., keratin projecting inwards to the epithelium and basal layers to the rest of the tissue section from a clinically significant viewpoint
The Capaciousness of No: Affective Refusals as Literacy Practices
© 2020 The Authors. Reading Research Quarterly published by Wiley Periodicals, Inc. on behalf of International Literacy Association The authors considered the capacious feeling that emerges from saying no to literacy practices, and the affective potential of saying no as a literacy practice. The authors highlight the affective possibilities of saying no to normative understandings of literacy, thinking with a series of vignettes in which children, young people, and teachers refused literacy practices in different ways. The authors use the term capacious to signal possibilities that are as yet unthought: a sense of broadening and opening out through enacting no. The authors examined how attention to affect ruptures humanist logics that inform normative approaches to literacy. Through attention to nonconscious, noncognitive, and transindividual bodily forces and capacities, affect deprivileges the human as the sole agent in an interaction, thus disrupting measurements of who counts as a literate subject and what counts as a literacy event. No is an affective moment. It can signal a pushback, an absence, or a silence. As a theoretical and methodological way of thinking/feeling with literacy, affect proposes problems rather than solutions, countering solution-focused research in which the resistance is to be overcome, co-opted, or solved. Affect operates as a crack or a chink, a tiny ripple, a barely perceivable gesture, that can persist and, in doing so, hold open the possibility for alternative futures
Test of Replica Theory: Thermodynamics of 2D Model Systems with Quenched Disorder
We study the statistics of thermodynamic quantities in two related systems
with quenched disorder: A (1+1)-dimensional planar lattice of elastic lines in
a random potential and the 2-dimensional random bond dimer model. The first
system is examined by a replica-symmetric Bethe ansatz (RBA) while the latter
is studied numerically by a polynomial algorithm which circumvents slow glassy
dynamics. We establish a mapping of the two models which allows for a detailed
comparison of RBA predictions and simulations. Over a wide range of disorder
strength, the effective lattice stiffness and cumulants of various
thermodynamic quantities in both approaches are found to agree excellently. Our
comparison provides, for the first time, a detailed quantitative confirmation
of the replica approach and renders the planar line lattice a unique testing
ground for concepts in random systems.Comment: 16 pages, 14 figure
Supernova Neutrinos, Neutrino Oscillations, and the Mass of the Progenitor Star
We investigate the initial progenitor mass dependence of the early-phase
neutrino signal from supernovae taking neutrino oscillations into account. The
early-phase analysis has advantages in that it is not affected by the time
evolution of the density structure of the star due to shock propagation or
whether the remnant is a neutron star or a black hole. The initial mass affects
the evolution of the massive star and its presupernova structure, which is
important for two reasons when considering the neutrino signal. First, the
density profile of the mantle affects the dynamics of neutrino oscillation in
supernova. Second, the final iron core structure determines the features of the
neutrino burst, i.e., the luminosity and the average energy. We find that both
effects are rather small. This is desirable when we try to extract information
on neutrino parameters from future supernova-neutrino observations. Although
the uncertainty due to the progenitor mass is not small for intermediate
(), we
can, nevertheless, determine the character of the mass hierarchy and whether
is very large or very small.Comment: 8 pages, 15 figure
- …