JOURNAL OF APPLIED AND COMPUTATIONAL MECHANICS
Year:2017 | Volume:3 | Issue:2|Papers Count:7

In this paper, the shape influence of piezoelectric beams including triangle, trapezoid, rectangle, invertedtrapezoid, convex parabola, concave parabola, and comb-shaped (a combination of two triangular beams with aconnector of 4 mm length) are addressed and analyzed by FEM. The analysis is performed for a bimorphpiezoelectric beam. The analyzed parameters include the beam length, thickness and width of the piezoelectriclayer. The study is performed using COMSOL Multiphysics software for all seven shapes. The results show thatdue to the mechanical properties of the beams, the natural frequency of the triangular beam is more for allconsidered parameters. In addition, as the width of the beam end increases, the natural frequency reduces, too. Since natural frequency is inversely related to electric power, the inverted trapezoidal beam has the highestelectric power and the triangular beam has the lowest one.

In this paper, the flow, thermal and concentration analyses of blood as a third grade with gold as nanoparticlesthrough a porous channel are carried out using regular perturbation method. The analysis are carried out usingVogel’ s model of temperature-dependent viscosity. The developed models were used to investigate the effectsof the nano particles on the concentration, temperature and velocity of the fluid as it flows through the porousmedium of a hollow channel in the presence of magnetic field. Also, the effects of fluid parameters such asBrownian motion, thermophoresis, viscous dissipation, non-Newtonian, porosity, magnetohydrodynamics(MHD), diffusion constant at various values on the fluid were established. The results generated in this workwere found to be in good agreement with the results found in litereture.

In this work, effects of different tool pin profiles of flat and tapered shoulder geometries on the peaktemperature in friction stir welding are investigated analytically. The developed models used for the analyticalinvestigations considered the welding process as a combination or mixture of the pure sliding and the puresticking. From the results, the amount of heat generation and the peak temperature are directly proportional tothe number of edges in the pin profiles in such a way that the heat generated and peak temperature in theprofiles increases from the triangular pin profile to hexagonal pin profile. Also, the rate of heat generation andthe peak temperature in flat shoulder are greater than in tapered/conical shoulder. The results in this work arevalidated with experimental and the past theoretical results and good agreements are achieved.

The Casimir attraction can significantly interfere with the physical response of nanoactuators. The intensityof the Casimir force depends on the geometries of interacting bodies. The present paper is conducted to modelthe influence of the Casimir attraction on the electrostatic stability of nanoactuators made of the cylindricalconductive nanowire/nanotube. An asymptotic solution, based on the path-integral approach, is employed toinvestigate the Casimir force. Moreover, the continuum theory is employed to derive the constitutive equationof the actuator. On the other hand, the governing nonlinear equations are solved by three different approaches, and also various perspectives of the issue including comparison with the van der Waals (vdW) force regime, the variation of instability parameters and the effect of geometry are addressed.

In this paper, the dynamic response of resonating nano-beams is investigated using a strain gradient elasticitytheory. A nonlinear model is obtained based on the Galerkin decomposition method to find the dynamicresponse of the investigated beam around its statically deflected position. The mid-plane stretching, axialresidual stress and nonlinear interaction due to the electrostatic force on the deflected beam are included in theproposed nonlinear beam model. Comparing the beam natural frequency using strain gradient theory withexperimental data shows an excellent agreement among both approaches. The normalized natural frequency isshown to be increasing nonlinearly with the decrease of the applied DC voltage as well as beam thickness. Theresults also reveal that increasing the tension axial stress increases the natural frequency; however its influencedecreases when decreasing the beam thickness. To investigate the effect of AC actuation voltage on the beamresonant frequency, a Lindstedt-Poincare based perturbation method is utilized and validated by comparisonwith experimental data. The results show that increasing the AC actuation voltage makes the beam stiffer byincreasing its resonant frequency.

Image segmentation is a fundamental approach in the field of image processing and based on user’ sapplication. This paper propose an original and simple segmentation strategy based on the EM approach thatresolves many informatics problems about hyperspectral images which are observed by airborne sensors. In afirst step, to simplify the input color textured image into a color image without texture. The final segmentationis simply achieved by a spatially color segmentation using feature vector with the set of color valuescontained around the pixel to be classified with some mathematical equations. The spatial constraint allowstaking into account the inherent spatial relationships of any image and its color. This approach provideseffective PSNR for the segmented image. These results have the better performance as the segmented imagesare compared with Watershed & Region Growing Algorithm and provide effective segmentation for theSpectral Images & Medical Images.

Today, due to the natural decline of oil exploitation, the use of methods of oil recovery, has madesignificant progress. However, these methods are accompanied by accumulation and deposition of mineraldeposits in oil field installations. In the present study, aqueous solutions, strontium sulfate, barium sulfate, manganese sulfate and nickel sulfate are studied, in terms of EUNIQUAC model and genetic algorithms. Based on the findings of this article, as temperature increases, in order to increase the solubility of thesystem, the ionic strength decreases; but with increasing pressure, the solubility of barium sulfate increases. Meanwhile, in this article, to evaluate water activity, aqueous solutions of manganese sulfate and nickelsulfate is studied.