Density, viscosity, refractive index, and related thermophysical properties of dibutyl ether +2-butanol + cyclohexane ternary systems

Producción CientíficaNew measured data for density, (ρ), dynamic and kinematic viscosities, (μD and μc), and refractive index, (nD), are presented at T = 298.15 K and p = 0.1 MPa for binary and ternary mixtures containing dibutyl ether, 2-butanol, and cyclohexane. As a result, the derived properties are estimated based on the measured data. Excess molar volume, (VE), dynamic viscosity deviation (ΔμD), and deviation in refractive index, (ΔnD), as derived properties, are fitted using the Redlich–Kister equation. In addition, perturbed-chain statistical associating fluid theory equation of state is employed to correlate the measured data of density

New Analytical Model of human body arm movements under various solicitations by the finite Element Analysis

The movement of a human arm body is complex since it is composed of an assembly of elements in three-dimensional movement, thus, modeling this arm is required to write its various movements using systems of simple and convergent equations. Therefore, the finite element method is an essential method to write and analyze the different kinematic and dynamic movements of the arm. The position of stress, strains, velocity, and acceleration in the different limbs of the arm have been determined and analyzed. The applications of this topic may have a great importance in the field of biomechanics, especially when the material considered is of the isotropic or orthotropic type. Good comparisons were observed for both types of materials investigated in our research

Elaboration and characterization of PMN–xPT solid ceramics used in a numerical simulation of a piezoelectric transducer for a loudspeaker application

International audienceSolid ceramics (1 − x)PbMg1/3Nb2/3O3–xPbTiO3 (PMN–xPT) have been prepared and characterized in the present work. Three PMN–xPT compositions were used with x taking the values of 0.31, 0.33 and 0.35. For the three compositions, an analysis of the dielectric behavior has been made, in order to determine the phase transition temperatures and Curie’s temperatures by measuring the dielectric constants and the dielectric losses as a function of temperature and frequency. A typical behavior to that of ferroelectric relaxor materials was noted by the increase of the PT’s rate. Ferroelectric character was analyzed by studying the evolution of polarization as a function of the applied field for the different samples, with the variation of the temperature. The hysteresis loop was strongly modified by the action of the temperature. The remnant polarization, as well as the coercive field, decreases with the increase of the temperature and increase with the increase of the applied field. Due to their high dielectric and ferroelectric properties, a numerical simulation by a finite element analysis software was made on PMN–0.35PT pellets, used for a loudspeaker application. The mechanical and acoustic behaviors of the piezoelectric transducer were investigated

Sensors and energy harvesters based on (1–x)PMN-xPT piezoelectric ceramics

With recent advancements in energy conversion mechanisms, piezoelectric ceramics (1–x)PbMg1/3 Nb2/3Ο3-xPbTiΟ3 (1–x)PMN-xPT have demonstrated their abilities for converting mechanical vibrations into electricity. Three (1–x)PMN-xPT compositions were used in the present work with (x = 0.25, 0.31 and 0.33). The purpose of this paper is to investigate their piezoelectric performance as generators for energy harvesting applications. The energy harvester is numerically analyzed in this work. It consists of a piezoelectric bimorph clamped at one end to vibrating machinery, and a proof mass mounted on its other end. The energy harvester is also analyzed and experimental measurements of the harvested power are compared to the simulation results. A good agreement was observed between the experimental and the simulations results. According the application to exploit the vibrations of a hot air extractor, the results show that the harvested energy density of solid ceramics (1–x)PMN-xPT is 0.043 W/m2

Dielectric and mechanical optimization properties of porous poly(ethylene-co-vinyl acetate) copolymer films for pseudo-piezoelectric effect

International audienceIn this article, the authors present a porous copolymer film with pseudo-piezoelectric effects as a new candidate material for sensing applications. Porous films of poly(ethylene-co-vinyl acetate) (EVA) with a thicknesses ranging from 160 to 310 μm are fabricated by a coextrusion chemical foaming process and charged using a high-voltage contact charging process. Output performances (piezoelectric constant and relative permittivity) with related thermal/mechanical stability are specifically studied as a function of the film porosity and of the electrical charging process. The piezoelectric constant d33 increases with the cell porosity and an interesting piezoelectric constant close to 5.1 pC/N is achieved with a porous EVA film containing 65% of porosity. Actual results are then discussed using a theoretical solid–gas multilayer model to describe and predict the pseudo-piezoelectric effect of porous polymer materials. The originality of this work lies in the fact that all the steps leading to optimize pseudo piezoelectric films are included, and also in the use of EVA which is not a standard piezoelectric material. Therefore, this work is a contribution in the development of low-cost piezoelectric materials with potential applications as sensor in different fields such as medical, security, environment, sport, and transport. POLYM. ENG. SCI., 59:1455–1461 2019. © 2019 Society of Plastics Engineers. © 2019 Society of Plastics Engineer

Structural, thermal and dielectric properties of Pb(Mg

Ceramics arising from Pb(Mg1/3Nb2/3)1‑x TixO3 with composition near the morphotropic phase boundary (MPB) were prepared by the modified solid-state reaction method. The synthesized ceramics were characterized, and then the operating principles of pyroelectric and piezoelectric harvesters are reviewed. In addition, the dielectric behavior is measured to determine the dielectric constant and losses at different temperatures and frequencies. The typical behavior of a ferroelectric relaxer was observed by adding the PbTiO3 phase. The thermal properties are also analyzed by PPE calorimetry, presaging a one-dimensional heat-flow process. As a result, the dielectric and thermal behaviors of the as-prepared ceramics as well as their thermal stability are intimately linked to the PbTiO3 addition to PbMgl/3Nb2/3O3 phase. These materials exhibit good physical performances, which makes them promising candidates for pyroelectric micro-generators (PEG), cooling systems and infrared applications