Nonlocal vibration analysis of the three-layered FG nanoplates subjected to applied electric potential considering thickness stretching effect

Comprehensive nonlocal piezoelasticity relations are developed in this paper for a sandwich functionally graded nanoplate subjected to applied electric potential based on higher-order shear and normal deformation theory. To account thickness stretching effect, the higher-order shear and normal deformation theory is developed. Based on this theory, the transverse deflection is decomposed into bending, shear and stretching portions in which the third term is reflected variation of transverse deflection along the thickness direction. Size dependency is accounted in governing equations based on nonlocal elasticity theory. The sandwich nanoplate is made of a functionally graded core integrated with two piezoelectric layers. Distribution of material properties are assumed according to the power-law function in the thickness direction. The Hamilton’s principle is used to derive governing equations of motion. Navier’s technique is implemented to solve partial differential equation of motion. Accuracy and efficiency of the presented technique are verified by a comparison between obtained results and existing results in literature for two cases including and excluding thickness stretching effect. The comparison between the results with and without thickness stretching effect can justify necessity of present work. Large parametric analysis is organized to investigate effect of significant parameters such as external applied voltage, nonlocal parameter, non-homogeneous index, stretching effect, length-to-thickness, length-to-width and core-to-face sheet thickness ratios on the vibrational behavior of the system. As an important result of this study, one can conclude that accounting thickness stretching effect leads to decrease of natural frequencies in comparison with cases disregards thickness stretching.

Nozzle-Shaped Electrode Configuration for Dielectrophoretic 3D-Focusing of Microparticles

: An experimentally validated mathematical model of a microfluidic device with nozzle-shaped electrode configuration for realizing dielectrophoresis based 3D-focusing is presented in the article. Two right-triangle shaped electrodes on the top and bottom surfaces make up the nozzle-shaped electrode configuration. The mathematical model consists of equations describing the motion of microparticles as well as profiles of electric potential, electric field, and fluid flow inside the microchannel. The influence of forces associated with inertia, gravity, drag, virtual mass, dielectrophoresis, and buoyancy are taken into account in the model. The performance of the microfluidic device is quantified in terms of horizontal and vertical focusing parameters. The influence of operating parameters, such as applied electric potential and volumetric flow rate, as well as geometric parameters, such as electrode dimensions and microchannel dimensions, are analyzed using the model. The performance of the microfluidic device enhances with an increase in applied electric potential and reduction in volumetric flow rate. Additionally, the performance of the microfluidic device improves with reduction in microchannel height and increase in microparticle radius while degrading with increase in reduction in electrode length and width. The model is of great benefit as it allows for generating working designs of the proposed microfluidic device with the desired performance metrics.

Initial Jet Before the Onset of Effective Electrospinning of Polymeric Nanofibers

Initial jet usually has a large primary droplet hanging at flying end before the onset of effective electrospinning. The primary droplet is undesired as its diameter is several orders of magnitude higher than that of electrospun nanofibres. A new method is used to derive micro-scaled initial jet and fine primary droplet under applied small-aperture needle by utilizing low solution flow rate and pre-applied electric potential before the extrusion of polymeric solution out of the needle. Small-aperture needle reduces the base of conical pendant, while low solution flow rate prevents a fluidic inrush into conical pendant. The pre-applied electric potential preforms a miniature liquid cone, as an origin of initial jet, within the needle. The conic preformation reduces the formation time of Taylor cone in order to escape from a swollen Taylor cone under a continuous inflow of polymeric solution. The miniature conical pendant grows so acute that it emits fine primary droplet rapidly from its tip with accumulated ions. Carrying primary droplet, thin initial jet experiences axial elongation and circumferential rotation in the space.

Definition of the transfer coefficient in electrochemistry (IUPAC Recommendations 2014)

The transfer coefficient α is a quantity that is commonly employed in the kinetic investigation of electrode processes. An unambiguous definition of the transfer coefficient, independent of any mechanistic consideration and exclusively based on experimental data, is proposed. The cathodic transfer coefficient αc is defined as –(RT/F)(dln|jc|/dE), where jc is the cathodic current density corrected for any changes in the reactant concentration on the electrode surface with respect to its bulk value, E is the applied electric potential, and R, T, and F have their usual significance. The anodic transfer coefficient αa is defined similarly, by simply replacing jc with the anodic current density and the minus sign with the plus sign. This recommendation aims at clarifying and improving the definition of the transfer coefficient reported in the 3rd edition of the IUPAC Green Book.