Wave propagation in a non-local piezoelectric phononic crystal Timoshenko nanobeam

By applying non-local elasticity theory and plane wave expansion (PWE) method to Timoshenko beam, the calculation method of band structure of a non-local piezoelectric phononic crystal (PC) Timoshenko nanobeam is proposed and formulized. In order to investigate the properties of wave propagating in the nanobeam in detail, bandgaps of first four orders are picked, and the corresponding influence rules of thermo-electro-mechanical coupling fields, non-local effect and geometric parameters on bandgaps are studied. During the research works, temperature variation, external electrical voltage and axial force are chosen as the influencing parameters related to the thermo-electro-mechanical coupling fields. Scale coefficient is chosen as the influencing parameter corresponding to non-local effect. Length ratio between materials PZT-4 and epoxy and height-width ratio are chosen as the influencing parameters of geometric parameters. Moreover, all the band structures and influence rules of Timoshenko nanobeam are compared to those of Euler nanobeam. The results are expected to be of help for the design of micro and nanodevices based on piezoelectric periodic nanobeams.

Learning a Local Language at School in Indonesian Setting

This study attempted to identify how attitude and motivation and the success in language achievement are correlated. The subjects of this study consisted 73 students who had been learning Lampungese as a local language in Indonesia. The data on the attitude and motivation was arranged in a Likert- Style format and the data on the success in language learning was collected through a test consisting four language skills. The data collected from the questionnaires were analyzed to measure internal consistency of hypothesized scales by using item-to scale coefficient. To determine how the variabels were correlated, correlation analyses were undertaken. The result shows that students’ attitude predicted motivation, and, in turn, their motivation predicted their language performance; it may be interpreted that attitude predicts motivation through the mediation of motivation.

Nonlocal Approaches for the Vibration of Lattice Plates Including Both Shear and Bending Interactions

The present study investigates the dynamical behavior of lattice plates, including both bending and shear interactions. The exact natural frequencies of this lattice plate are calculated for simply supported boundary conditions. These exact solutions are compared with some continuous nonlocal plate solutions that account for some scale effects due to the lattice spacing. Two continualized and one phenomenological nonlocal UflyandMindlin plate models that take into account both the rotary inertia and the shear effects are developed for capturing the small length scale effect of microstructured (or lattice) thick plates by associating the small length scale coefficient introduced in the nonlocal approach to some length scale coefficients given in a Taylor or a rational series expansion. The nonlocal phenomenological model constitutes the stress gradient Eringen’s model applied at the plate scale. The continualization process constructs continuous equation from the one of the discrete lattice models. The governing partial differential equations are solved in displacement for each nonlocal plate model. An exact analytical vibration solution is obtained for the natural frequencies of the simply supported rectangular nonlocal plate. As expected, it is found that the continualized models lead to a constant small length scale coefficient, whereas for the phenomenological nonlocal approaches, the coefficient, calibrated with respect to the element size of the microstructured plate, is structure-dependent. Moreover, comparing the natural frequencies of the continuous models with the exact discrete one, it is concluded that the continualized models provide much more accurate results than the nonlocal Uflyand–Mindlin plate models.

Thermal and Small-Scale Effects on Vibration of Embedded Armchair Single-Walled Carbon Nanotubes

The non-local Timoshenko beam theory has been implemented to investigate the free vibration of armchair single-walled carbon nanotubes embedded in elastic medium including the thermal effects. The mechanical properties of nano-composite (carbon nanotubes and polymer matrix) are treated as functions of temperature change and the analytical solution is derived according to the governing equations of non-local Timoshenko beam models. The equivalent Young’s modulus and shear modulus for armchair single-walled carbon nanotubes are derived using an energy-equivalent model. Influence of small-scale coefficient, vibrational mode number, matrix of nano-composite and aspect ratio on the frequency ratio of the armchair single-walled carbon nanotubes including the thermal effect are studied and discussed. The research work reveals the significance of the small-scale coefficient, the vibrational mode number, the elastic medium and the aspect ratio on the frequency ratio. It is also demonstrated that some properties of free vibrations of single-walled carbon nanotubes are dependent on the change of temperature.

Eringen’s small length scale coefficient for vibration of axially loaded nonlocal Euler beams with elastic end restraints

This paper presents the calibration of Eringen’s small length scale coefficient

Aspects Regarding the Establishment of the Scale Coefficient in the Case of Distances Measurements in an Geodetic Network

The paper analyzes the possibility to establish the coefficient of scale towards the total station scale triangulation network in the conduct of geodetic and topographic observations in the points with known coordinates (old points) or points whose coordinates we want to determine (new points). The purpose of the study is undertaken to simplify computing operations to reduce distances measured from the topographic surface to the Stereo 70 projection plan.

A Novel Digital Watermark Algorithm Based on a Fingerprint Image

A fingerprint-based digital watermark algorithm for image processing is proposed. Firstly, the watermark is done the scrambling by the Arnold transform. Secondly, the digital watermarking is done the chaos encryption by the Tent chaos sequence. Thirdly, the original image is transformed by the discrete Curvelet transformation. Finally, the watermarking image is embedded into detail scale coefficient matrix of Curvelet transform. The experimental result demonstrated that watermarking extraction’s effect is acceptable. Moreover, severe image attacks such as noise, image crop and JPEG compression and so on are survived by the embedded watermarking.