2,866 research outputs found
Effects of internal heat generation, thermal radiation, and buoyancy force on boundary layer over a vertical plate with a convective boundary condition
In this paper we analyze the effects of internal heat generation, thermal radiation, and buoyancy
force on the laminar boundary layer about a vertical plate in a uniform stream of fluid under a
convective surface boundary condition. In the analysis, we assumed that left surface of the plate
is in contact with a hot fluid while a stream of cold fluid flows steadily over the right surface
with a heat source that decays exponentially. Similarity variable method is applied to the
governing non-linear partial differential equations. The transformed into a set of coupled nonlinear
ordinary differential equations are solved numerically by applying shooting iteration
technique together with fourth order Runge-Kutta integration scheme. The effects of Prandtl
number, local Biot number, the internal heat generation parameter, thermal radiation, and the
local Grashof number on the velocity and temperature profiles are illustrated and interpreted in
physical terms. A comparison with previously published results in special case of the problem
shows an excellent agreement
Resonant oscillations of a plate in an electrically conducting rotating Johnson-Segalman fluid
AbstractAn analysis of hydromagnetic flow is examined in a semi-infinite expanse of electrically conducting rotating Johnson-Segalman fluid bounded by nonconducting plate in the presence of a transverse magnetic field and the governing equations are modeled first time. The structure of the velocity distribution and the associated hydromagnetic boundary layers are investigated including the case of resonant oscillations. It is shown that unlike the hydrodynamic situation for the case of resonance, the hydromagnetic steady solution satisfies the boundary condition at infinity. The inherent difficulty involved in the hydrodynamic resonance case has been resolved in the presence analysis
On design of robust fault detection filter in finite-frequency domain with regional pole assignment
This brief is concerned with the fault detection (FD) filter design problem for an uncertain linear discrete-time system in the finite-frequency domain with regional pole assignment. An optimized FD filter is designed such that: 1) the FD dynamics is quadratically D-stable; 2) the effect from the exogenous disturbance on the residual is attenuated with respect to a minimized H∞-norm; and 3) the sensitivity of the residual to the fault is enhanced by means of a maximized H--norm. With the aid of the generalized Kalman-Yakubovich-Popov lemma, the mixed H--/H∞ performance and the D-stability requirement are guaranteed by solving a convex optimization problem. An iterative algorithm for designing the desired FD filter is proposed by evaluating the threshold on the generated residual function. A simulation result is exploited to illustrate the effectiveness of the proposed design technique.This work was supported in part by the Deanship of Scientific Research (DSR) at King Abdulaziz University in Saudi Arabia under Grant 16-135- 35-HiCi, the National Natural Science Foundation of China under Grants
61134009 and 61203139, the Royal Society of the U.K., and the Alexander von Humboldt Foundation of Germany
Information Diffusion Power of Political Party Twitter Accounts During Japan's 2017 Election
In modern election campaigns, political parties utilize social media to
advertise their policies and candidates and to communicate to electorates. In
Japan's latest general election in 2017, the 48th general election for the
Lower House, social media, especially Twitter, was actively used. In this
paper, we perform a detailed analysis of social graphs and users who retweeted
tweets of political parties during the election. Our aim is to obtain accurate
information regarding the diffusion power for each party rather than just the
number of followers. The results indicate that a user following a user who
follows a political party account tended to also follow the account. This means
that it does not increase diversity because users who follow each other tend to
share similar values. We also find that followers of a specific party
frequently retweeted the tweets. However, since users following the user who
follow a political party account are not diverse, political parties delivered
the information only to a few political detachment users.Comment: The 10th International Conference on Social Informatics (SocInfo
2018
Influence of heterogeneous-homogeneous reactions in thermally stratified stagnation point flow of an Oldroyd-B fluid
AbstractThis communication explores the effects of homogeneous-heterogeneous reactions in thermally stratified mixed convection flow of an Oldroyd-B fluid. Flow situation is addressed when the diffusion coefficients of the reactant and auto catalyst are equal. The stagnation point flow towards a stretching surface is discussed. Mathematical equations are developed for velocity, temperature and concentration functions through boundary layer theory. Resulting differential systems are computed for the convergent series solutions. Influences of various pertinent variables on the velocity, temperature and concentration are discussed. Comparison of present study is shown with the previous results. The outcomes are found in very good agreement
An oscillating hydromagnetic non-Newtonian flow in a rotating system
AbstractAn exact solution of an oscillatory boundary layer flow bounded by two horizontal flat plates, one of which is oscillating in its own plane and the other at rest, is developed. The fluid and the plates are in a state of solid body rotation with constant angular velocity about the z-axis normal to the plates. The fluid is assumed to be second grade, incompressible, and electrically conducting. A uniform transverse magnetic field is applied. During the mathematical analysis, it is found that the steady part of the solution is identical to that of viscous fluid. The structure of the boundary layers is also discussed. Several known results of interest are found to follow as particular cases of the solution of the problem considered
Convective Heat Transfer Analysis on Prandtl Fluid Model with Peristalsis
The effects of magnetohydrodynamic (MHD) on peristaltic transport of Prandtl fluid in a symmetric channel have been studied under the assumptions of long wave length and low-Reynolds number. Channel walls are considered compliant in nature. Series solutions of axial velocity, stream function and temperature are given by using regular perturbation technique for small values of Prandtl fluid parameter. The effects of physical parameters on the velocity, streamlines and temperature are examined by plotting graphs
Additively Manufactured Perforated Superstrate to Improve Directive Radiation Characteristics of Electromagnetic Source
© 2013 IEEE. Additively manufactured perforated superstrate (AMPS) is presented to realize directive radio frequency (RF) front-end antennas. The superstrate comprises spatially distributed dielectric unit-cell elements with square perforations, which creates a pre-defined transmission phase delay pattern in the propagating electric field. The proposed square perforation has superior transmission phase characteristics compared to traditionally machined circular perforations and full-wave simulations based parametric analysis has been performed to highlight this supremacy. The AMPS is used with a classical electromagnetic-bandgap resonator antenna (ERA) to improve its directive radiation characteristics. A prototype is developed using the most common, low-cost and easily accessible Acrylonitrile Butadiene Styrene (ABS) filament. The prototype was rapidly fabricated in less than five hours and weighs 139.3 g., which corresponds to the material cost of only 2.1 USD. The AMPS has remarkably improved the radiation performance of ERA by increasing its far-field directivity from 12.67 dB to 21.12 dB and reducing side-lobe level from-7.3 dB to-17.2 dB
Partial slip effect on heat and mass transfer of MHD peristaltic transport in a porous medium
This research looks at the effects of partial slip on heat and mass transfer of peristaltic transport. The magnetohydrodynamic (MHD) flow of viscous fluid in a porous asymmetric channel has been considered. The exact solutions for the stream function, longitudinal pressure gradient, longitudinal velocity, shear stress, temperature and concentration fields are derived by adopting long wavelength and small Reynolds number approximations. The results showed that peristaltic pumping and trapping are reduced with increasing velocity slip parameter. Furthermore, temperature increases with increasing thermal slip parameter. Moreover, the concentration profile decreases with increasing porosity parameter, Schmidt number and concentration slip parameter. Comparisons with published results are found to be in good agreement
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