Abstract: This paper aims to present a study, with the theoretical concepts and applications of the Quadcopter, using the MATLAB simulator. In order to use this tool, the study of the stability of the drone through a Proportional - Integral - Derivative (PID) controller will be presented. After the stability study, some tests are done on the simulator and its results will be presented. From the mathematical model, it is possible to find the Newton-Euler angles, so that it is possible to stabilize the quadcopter in a certain position in the air, starting from the ground. In order to understand the impact of the controllers gain values on the stabilization of the Euler-Newton angles, three conditions will be tested with different controller gain values.
Abstract: A formulation of postbuckling analysis of end supported rods under self-weight has been presented by the variational method. The variational formulation involving the strain energy due to bending and the potential energy of the self-weight, are expressed in terms of the intrinsic coordinates. The variational formulation is accomplished by introducing the Lagrange multiplier technique to impose the boundary conditions. The finite element method is used to derive a system of nonlinear equations resulting from the stationary of the total potential energy and then Newton-Raphson iterative procedure is applied to solve this system of equations. The numerical results demonstrate the postbluckled configurations of end supported rods under self-weight. This finite element method based on variational formulation expressed in term of intrinsic coordinate is highly recommended for postbuckling analysis of end-supported rods under self-weight.
Abstract: Newton-Lagrange Interpolations are widely used in
numerical analysis. However, it requires a quadratic computational
time for their constructions. In computer aided geometric design
(CAGD), there are some polynomial curves: Wang-Ball, DP and
Dejdumrong curves, which have linear time complexity algorithms.
Thus, the computational time for Newton-Lagrange Interpolations
can be reduced by applying the algorithms of Wang-Ball, DP and
Dejdumrong curves. In order to use Wang-Ball, DP and Dejdumrong
algorithms, first, it is necessary to convert Newton-Lagrange
polynomials into Wang-Ball, DP or Dejdumrong polynomials. In
this work, the algorithms for converting from both uniform and
non-uniform Newton-Lagrange polynomials into Wang-Ball, DP and
Dejdumrong polynomials are investigated. Thus, the computational
time for representing Newton-Lagrange polynomials can be reduced
into linear complexity. In addition, the other utilizations of using
CAGD curves to modify the Newton-Lagrange curves can be taken.
Abstract: In this paper, an enhancement of the heat transfer using non-Newtonian nanofluids by magnetohydrodynamic (MHD) mixed convection along stretching sheets embedded in an isotropic porous medium is investigated. Case of the Maxwell nanofluids is studied using the two phase mathematical model of nanofluids and the Darcy model is applied for the porous medium. Important effects are taken into account, namely, non-linear thermal radiation, convective boundary conditions, electromagnetic force and presence of the heat source/sink. Suitable similarity transformations are used to convert the governing equations to a system of ordinary differential equations then it is solved numerically using a fourth order Runge-Kutta method with shooting technique. The main results of the study revealed that the velocity profiles are decreasing functions of the Darcy number, the Deborah number and the magnetic field parameter. Also, the increase in the non-linear radiation parameters causes an enhancement in the local Nusselt number.
Abstract: This work is the modeling and simulation of fluid flow (liquid) through porous media. This type of flow occurs in many situations of interest in applied sciences and engineering, fluid (oil) consists of several individual substances in pure, single-phase flow is incompressible and isothermal. The porous medium is isotropic, homogeneous optionally, with the rectangular format and the flow is two-dimensional. Modeling of hydrodynamic phenomena incorporates Darcy's law and the equation of mass conservation. Correlations are used to model the density and viscosity of the fluid. A finite volume code is used in the discretization of differential equations. The nonlinearity is treated by Newton's method with relaxation coefficient. The results of the simulation of the pressure and the mobility of liquid flowing through porous media are presented, analyzed, and illustrated.
Abstract: As the continuation to the previous studies of gravitational frequency shift, gravitational time dilation, gravitational light bending, gravitational waves, dark matter, and dark energy are explained in the context of Newtonian mechanics. The photon is treated as the particle with mass of hν/C2 under the gravitational field of much larger mass of M. Hence the quantum mechanics theory could be applied to gravitational field on cosmology scale. The obtained results are the same as those obtained by general relativity considering weak gravitational field approximation; however, the results are different when the gravitational field is substantially strong.
Abstract: The paper presents an approach to improve the reliability and reduce line losses of practical distribution system applying network reconfiguration. The change of the topology redirects the power flow within the distribution network to obtain better performance of the system. Practical distribution network (Pyigyitagon Industrial Zone (I)) is used as the case study network. The detailed calculations of the reliability indices are done by using analytical method and power flow calculation is performed by Newton-Rephason solver. The comparison of various network reconfiguration techniques are described with respect to power loss and reliability index levels. Finally, the optimal reconfigured network is selected among difference cases based on the two factors: the most reliable network and the least loss minimization.
Abstract: This paper presents a comparative study of the Gauss Seidel and Newton-Raphson polar coordinates methods for power flow analysis. The effectiveness of these methods are evaluated and tested through a different IEEE bus test system on the basis of number of iteration, computational time, tolerance value and convergence.
Abstract: The Oscillatory electroosmotic flow (OEOF) in power
law fluids through a microchannel is studied numerically. A
time-dependent external electric field (AC) is suddenly imposed
at the ends of the microchannel which induces the fluid motion.
The continuity and momentum equations in the x and y direction
for the flow field were simplified in the limit of the lubrication
approximation theory (LAT), and then solved using a numerical
scheme. The solution of the electric potential is based on the
Debye-H¨uckel approximation which suggest that the surface potential
is small,say, smaller than 0.025V and for a symmetric (z : z)
electrolyte. Our results suggest that the velocity profiles across
the channel-width are controlled by the following dimensionless
parameters: the angular Reynolds number, Reω, the electrokinetic
parameter, ¯κ, defined as the ratio of the characteristic length scale
to the Debye length, the parameter λ which represents the ratio
of the Helmholtz-Smoluchowski velocity to the characteristic length
scale and the flow behavior index, n. Also, the results reveal that
the velocity profiles become more and more non-uniform across the
channel-width as the Reω and ¯κ are increased, so oscillatory OEOF
can be really useful in micro-fluidic devices such as micro-mixers.
Abstract: Flexible AC transmission system controllers play an important role in controlling the line power flow and in improving voltage profiles of the power system network. They can be used to increase the reliability and efficiency of transmission and distribution system. The modeling of these FACTS controllers in power flow calculations have become a challenging research problem. This paper presents a simple and systematic approach for a steady state power flow calculations of power system with STATCOM (Static Synchronous Compensator). It shows how systematically STATCOM can be implemented in conventional power flow calculations. The main contribution of this paper is to investigate this approach for two special conditions i.e. consideration of load increase pattern incorporating load change (active, reactive and both active and reactive) at all load buses simultaneously and the line contingencies under such load change. Such investigation proves to be relevant for determination of strategy for the optimal placement of STATCOM to enhance the voltage stability. The performance has been evaluated on many standard IEEE test systems. The results for standard IEEE-30 bus test system are presented here.
Abstract: Tire noise has a significant impact on ride quality
and vehicle interior comfort, even at low frequency. Reduction of
tire noise is especially important due to strict state and federal
environmental regulations. The primary sources of tire noise are the
low frequency structure-borne noise and the noise that originates from
the release of trapped air between the tire tread and road surface
during each revolution of the tire. The frequency response of the tire
changes at low and high frequency. At low frequency, the tension
and bending moment become dominant, while the internal structure
and local deformation become dominant at higher frequencies. Here,
we analyze tire response in terms of deformation and rolling velocity
at low revolution frequency. An Abaqus FEA finite element model
is used to calculate the static and dynamic response of a rolling tire
under different rolling conditions. The natural frequencies and mode
shapes of a deformed tire are calculated with the FEA package where
the subspace-based steady state dynamic analysis calculates dynamic
response of tire subjected to harmonic excitation. The analysis was
conducted on the dynamic response at the road (contact point of tire
and road surface) and side nodes of a static and rolling tire when
the tire was excited with 200 N vertical load for a frequency ranging
from 20 to 200 Hz. The results show that frequency has little effect on
tire deformation up to 80 Hz. But between 80 and 200 Hz, the radial
and lateral components of displacement of the road and side nodes
exhibited significant oscillation. For the static analysis, the fluctuation
was sharp and frequent and decreased with frequency. In contrast, the
fluctuation was periodic in nature for the dynamic response of the
rolling tire. In addition to the dynamic analysis, a steady state rolling
analysis was also performed on the tire traveling at ground velocity
with a constant angular motion. The purpose of the computation
was to demonstrate the effect of rotating motion on deformation and
rolling velocity with respect to a fixed Newtonian reference point.
The analysis showed a significant variation in deformation and rolling
velocity due to centrifugal and Coriolis acceleration with respect to
a fixed Newtonian point on ground.
Abstract: The experiment was carried out to study the performance of solar crop dryer coupled with reversed absorber type solar air heater (SD2). Excel software is used to analyse the raw data obtained from the drying experiment to develop a model. An attempt is made in this paper to correlate the collector efficiency, dryer efficiency and pick-up efficiency. All these efficiencies are dependent on the parameters such as solar flux, ambient temperature, collector outlet temperature and moisture content. The simulation equation was developed to predict the values of collector efficiency. The parameters a, n and drying constant k were determined from a plot of curve using a drying models. Experimental data of drying red chili in conventional solar dryer and solar dryer coupled with reversed absorber solar air heater was compared by fitting with three drying models. The moisture content will be rapidly reduced in solar dryer with reversed absorber due to higher drying temperatures. The best fit model was selected to describe the drying behavior of red chili. For SD2 the values of the coefficient of determination (R2=0.997), mean bias error (MBE=0.00026) and root mean square error (RMSE=0.016) were used to determine the goodness or the quality of the fit. Pages model showed a better fit to drying red chili among Newton model and Henderson & Pabis model.
Abstract: In this paper, the problem proposed by Von Karman is treated in the attendance of additional flow field effects when the liquid is spaced above the rotating rigid disk. To be more specific, a purely viscous fluid flow yield by rotating rigid disk with Navier’s condition is considered in both magnetohydrodynamic and hydrodynamic frames. The rotating flow regime is manifested with heat source/sink and chemically reactive species. Moreover, the features of thermophoresis and Brownian motion are reported by considering nanofluid model. The flow field formulation is obtained mathematically in terms of high order differential equations. The reduced system of equations is solved numerically through self-coded computational algorithm. The pertinent outcomes are discussed systematically and provided through graphical and tabular practices. A simultaneous way of study makes this attempt attractive in this sense that the article contains dual framework and validation of results with existing work confirms the execution of self-coded algorithm for fluid flow regime over a rotating rigid disk.
Abstract: The present work focuses on the investigation of the effect of non-Newtonian behavior on the oil-water stratified flow in a horizontal channel using ANSYS Fluent. Coupled level set and volume of fluid (CLSVOF) has been used to capture the evolving interface assuming unsteady, coaxial flow with constant fluid properties. The diametric variation of oil volume fraction, mixture velocity, total pressure and pressure gradient has been studied. Non-Newtonian behavior of oil has been represented by the power law model in order to investigate the effect of flow behavior index. Stratified flow pattern tends to assume dispersed flow pattern with the change in the behavior of oil to non-Newtonian. The pressure gradient is found to be very much sensitive to the flow behavior index. The findings could be useful in designing the transportation pipe line in petroleum industries.
Abstract: Gravity field is of great significance in geoscience, national economy and national security, and gravitational gradient measurement has been extensively studied due to its higher accuracy than gravity measurement. Gravity gradient sensor, being one of core devices of the gravity gradient instrument, plays a key role in measuring accuracy. Therefore, this paper starts from analyzing the working principle of the gravity gradient sensor by Newton’s law, and then considers the relative motion between inertial and non-inertial systems to build a relatively adequate mathematical model, laying a foundation for the measurement error calibration, measurement accuracy improvement.
Abstract: Detailed numerical calculations are illustrated in our investigation for unsteady natural convection heat and mass transfer of non-Newtonian Casson fluid along a vertical wavy surface. The surface of the plate is kept at a constant temperature and uniform concentration. To transform the complex wavy surface to a flat plate, a simple coordinate transformation is employed. The resulting partial differential equations are solved using the fully implicit finite difference method with SUR procedure. Flow and heat transfer characteristics are investigated for a wide range of values of the Casson parameter, the dimensionless time parameter, the buoyancy ratio and the amplitude-wavelength parameter. It is found that, the variations of the Casson parameter have significant effects on the fluid motion, heat and mass transfer. Also, the maximum and minimum values of the local Nusselt and Sherwood numbers increase by increase either the Casson parameter or the buoyancy ratio.
Abstract: The problem of thermal convection in temperature and
magnetic field sensitive Newtonian ferromagnetic liquid is studied
in the presence of uniform vertical magnetic field and throughflow.
Using a combination of Galerkin and shooting techniques the critical
eigenvalues are obtained for stationary mode. The effect of Prandtl
number (Pr > 1) on onset is insignificant and nonlinearity of
non-buoyancy magnetic parameter M3 is found to have no influence
on the onset of ferroconvection. The magnetic buoyancy number, M1
and variable viscosity parameter, V have destabilizing influences on
the system. The effect of throughflow Peclet number, Pe is to delay
the onset of ferroconvection and this effect is independent of the
direction of flow.
Abstract: The main purpose of this study is to show differences between the numerical solution of the flow through the artificial heart valve using Newtonian or non-Newtonian fluid. The simulation was carried out by a commercial computational fluid dynamics (CFD) package based on finite-volume method. An aortic bileaflet heart valve (Sorin Bicarbon) was used as a pattern for model of real heart valve replacement. Computed tomography (CT) was used to gain the accurate parameters of the valve. Data from CT were transferred in the commercial 3D designer, where the model for CFD was made. Carreau rheology model was applied as non-Newtonian fluid. Physiological data of cardiac cycle were used as boundary conditions. Outputs were taken the leaflets excursion from opening to closure and the fluid dynamics through the valve. This study also includes experimental measurement of pressure fields in ambience of valve for verification numerical outputs. Results put in evidence a favorable comparison between the computational solutions of flow through the mechanical heart valve using Newtonian and non-Newtonian fluid.
Abstract: In this paper geometrically nonlinear static behavior of laminated composite hollow super-elliptic beams is investigated using generalized differential quadrature method. Super-elliptic beam can have both oval and elliptic cross-sections by adjusting parameters in super-ellipse formulation (also known as Lamé curves). Equilibrium equations of super-elliptic beam are obtained using the virtual work principle. Geometric nonlinearity is taken into account using von-Kármán nonlinear strain-displacement relations. Spatial derivatives in strains are expressed with the generalized differential quadrature method. Transverse shear effect is considered through the first-order shear deformation theory. Static equilibrium equations are solved using Newton-Raphson method. Several composite super-elliptic beam problems are solved with the proposed method. Effects of layer orientations of composite material, boundary conditions, ovality and ellipticity on bending behavior are investigated.
Abstract: Non-Newtonian fluid properties can change the flow
behaviour significantly, its prediction is more difficult when thermal
effects come into play. Hence, the focal point of this work is the
wake flow behind a heated circular cylinder in the laminar vortex
shedding regime for thermo-viscous shear thinning fluids. In the case
of isothermal flows of Newtonian fluids the vortex shedding regime
is characterised by a distinct Reynolds number and an associated
Strouhal number. In the case of thermo-viscous shear thinning
fluids the flow regime can significantly change in dependence of
the temperature of the viscous wall of the cylinder. The Reynolds
number alters locally and, consequentially, the Strouhal number
globally. In the present CFD study the temperature dependence of
the Reynolds and Strouhal number is investigated for the flow of a
Carreau fluid around a heated cylinder. The temperature dependence
of the fluid viscosity has been modelled by applying the standard
Williams-Landel-Ferry (WLF) equation. In the present simulation
campaign thermal boundary conditions have been varied over a
wide range in order to derive a relation between dimensionless heat
transfer, Reynolds and Strouhal number. Together with the shear
thinning due to the high shear rates close to the cylinder wall
this leads to a significant decrease of viscosity of three orders of
magnitude in the nearfield of the cylinder and a reduction of two
orders of magnitude in the wake field. Yet the shear thinning effect
is able to change the flow topology: a complex K´arm´an vortex street
occurs, also revealing distinct characteristic frequencies associated
with the dominant and sub-dominant vortices. Heating up the cylinder
wall leads to a delayed flow separation and narrower wake flow,
giving lesser space for the sequence of counter-rotating vortices. This
spatial limitation does not only reduce the amplitude of the oscillating
wake flow it also shifts the dominant frequency to higher frequencies,
furthermore it damps higher harmonics. Eventually the locally heated
wake flow smears out. Eventually, the CFD simulation results of the
systematically varied thermal flow parameter study have been used
to describe a relation for the main characteristic order parameters.