Thermo-Electro-Mechanical Characterization of PDMS-Based Dielectric Elastomer Actuators

The present contribution aims towards a thermo-electro-mechanical characterization of dielectric elastomer actuators (DEA) based on polydimethylsiloxane (PDMS). To this end, an experimental setup is proposed in order to evaluate the PDMS-based DEA behavior under the influence of various rates of mechanical loading, different ambient temperatures, and varying values of an applied electric voltage. To obtain mechanical, electro-mechanical and thermo-mechanical experimental data, the passive behavior of the material, as well as the material’s response when electrically activated, was tested. The influence of the solid electrode on the dielectric layer’s surface was also examined. Moreover, this work focuses on the production of such DEA, the experimental setup and the interpretation and evaluation of the obtained mechanical hysteresis loops. Finite element modeling approaches were used in order to model the passive and the electro-mechanically active response of the material. A comparison between experimental and simulation results was performed.

Piezoelectric Configuration for Generating Electricity Using Waves Power

This study is aimed at determining the piezoelectric configuration for generating electricity from wave power through the design of a prototype model named Cov-TOTal. The study was carried out in Tomini Bay, Lopo Village, Batudaa Pantai District, Gorontalo Regency, located at approximately ±50 meters from the shoreline, while the piezoelectric construction was arranged in parallel with varying numbers of 28, 70, and 90 pieces. The result showed that the amount of piezoelectric configuration affects the value of the voltage and electric current generated by the Cov-TOTal model. Furthermore, the average electric voltage values were 17.58, 20.76, and 29.85 volts, while the average current was 1.16, 1.73, and 2.01 mA for each piezoelectric amount. Therefore, the largest values of power and electrical energy for each piezoelectric are 16.65 mW and 0.56 joules, 31.82 mW and 1.20 joules, and 44.59 mW and 1.77 joules, respectively. This study concluded that the amount of piezoelectric configuration has a significant effect on the voltage, current, power, and electrical energy produced.

Au-Ag/TiO2 Thin Films Preparation by Laser Ablation and Sputtering Plasmas for Its Potential Use as Photoanodes in Electrochemical Advanced Oxidation Processes (EAOP)

Titanium dioxide (TiO2) is widely used, studied, and synthesized using different methodologies. By a modification of the material, it can be applied to wastewater treatment. A combined sputtering-laser ablation setup was used to deposit TiO2 thin films modified, individually and simultaneously, with gold (Au) and silver (Ag). To investigate the effect of the metal incorporation in titanium and its impact on the photocatalytic activity, with dye discoloration as a pollutant compound model, the deposited films were characterized by UV–Vis, photoluminescence, and Raman spectroscopies, as well as by parallel beam X-ray diffraction. The results showed that films with different Au and Ag loads, and an 18 nm average crystallite size, were obtained. These metals have an essential effect on the deposited film’s compositional, structural, and optical properties, directly reflected in its photocatalytic activity. The photocatalytic test results using UV-Vis showed that, after 1 h of applying a 4.8 V electric voltage, a discoloration of up to 80% of malachite green (MG) was achieved, using ultraviolet (UV) light.

Snow Melting Performance of Graphene Composite Conductive Concrete in Severe Cold Environment

The use of conductive concrete is an effective way to address snow and ice accretion on roads in cold regions because of its energy saving and high efficiency without interruption of traffic. Composite conductive concrete was prepared using graphene, carbon fiber, and steel fiber, and the optimum dosage of graphene was explored with resistivity as the criterion. Subsequently, under the conditions of an initial temperature of −15 °C and a wind speed of 20 km/h, the extremely severe snow event environment in cold regions was simulated. The effects of electrode spacing and electric voltage on snow melting performance of conductive concrete slab were explored. Results showed that graphene can significantly improve the conductivity of conductive concrete; the optimal content of graphene was 0.4% of cement mass in terms of resistivity. The snow-melting power of conductive concrete slab decreased with increase in electrode spacing and increased with increase in on-voltage. For an optimal input voltage of 156 V and an optimal electrode spacing of 10 cm, the time required to melt a 24 h snow thickness (21 cm), accumulated during a simulated severe snow event, was only 2 h, which provides an empirical basis for the application of graphene composite conductive concrete to pavement snow melting in cold regions.

Treatment of textile industry wastewater by electrocoagulation technology

Experiments were carried out by treating the waste samples with electrocoagulation technology. This is done to determine the effectiveness of the removal of the electrocoagulation device against textile waste. The sample used is a synthetic sample with a concentration of 1091 mg/L Pt-Co units. The research was conducted twice with the first experiment being conducted to determine the most effective electrical voltage to remove the existing COD and color pollutants while the second experiment was conducted to determine the type of anode and cathode that was most effective in removing COD, Color, and heavy metal pollutants. In the first experiment, it was found that the electric voltage that could produce the best removal was 4 amperes and in the second experiment, the anode-cathode type with the highest % removal was Fe-Fe with % COD removal of 64.09639% and % color removal of 60.00619%. It was concluded that electrocoagulation method could effectively remove color and COD in waste water.

Lithium recovery from synthetic geothermal brine using electrodialysis method

The demand of lithium in the global market is experiencing a significant increase. The electric vehicle era is the driving force of this lithium increase phenomenon. Although the demand of lithium continues to increase every year, the available lithium resources are still not able to meet the demand, so that lithium resources with much greater potential are being considered. The main objective of this study is to extract lithium from a primary resource, geothermal brine, with a practical and environmentally friendly method. Research on the extraction of lithium resources from synthetic geothermal brine with a specific lithium composition using the electrodialysis (ED) method has been carried out. The ED device used is provided with electricity and is operated using temperature variations (30°C and 40°C) and variations in electric voltage (2 V and 4 V). The highest flux is achieved at an operating temperature of 40°C and a power supply voltage of 4 V.

The effect of discharge and water level on the electric voltage generated by the watermill

Potential energy is stored in water (in falling water) and kinetic energy (in flowing water) so that many studies have used water as alternative energy. This research was conducted to investigate the electric voltage generated by the waterwheel with different water flows and water levels. How to make a waterwheel are: (1) Prepare tools such as a plastic wheel, dynamo type (5V), cables, and lamps. (2) Connect the end of the plastic wheel to the end of the rotating dynamo. (3) Connect the cables to both ends of the dynamo. (4) Connect the two free ends of the cable to the lamp. (5) Test the waterwheel on running water and connect the cable to the multi-tester if you want to measure the voltage and current. The method used in this research is a demonstration experiment. The results of the study indicate that the electric voltage caused by the rotation of the wheel by running water can turn on the light. The greater the flow of water that flows, the greater the voltage generated and the lights get brighter. Furthermore, the experiments in this study can be used for the science learning process to students.

Exploring mechanical assonance for impact energy harvesting using acoustic metamaterials

Acoustic metamaterials are engineered to possess unique dynamic properties that are not commonly found in nature. It has been demonstrated that customizing the characteristics of their local features can help optimize their dynamic performance under specific loading conditions. Drawing inspiration from the literary device called “assonance,” the term “mechanical assonance” may be ascribed to the dynamic phenomenon realized by sequencing oscillators with tuned responses within a waveguide to engineer a prescribed wave transformation across it. In this context, assonance provides a framework to utilize resonant local features within a host structure or material and interactive mechanisms thereof as building blocks to create enriched functionalities for acoustic metamaterials. Using a discrete element representation for an acoustic metamaterial barrier (AMB), a numerical study is conducted to ascertain parametric dependence for assonant mechanisms related to resonator frequencies, their sequencing, and host material stiffness. Normalized metrics are extracted to estimate transmitted pulse mitigation under impact-type loading. It is found that resonator sets with octave spacing having the number of resonators of a specific frequency proportional to that frequency’s amplitude in the input spectrum is desirable for lower transmissibility. Further, sequencing the lowest frequency resonator set closest to the incident-side gives better performance. Engineering a high degree of impedance mismatch between host material sections is also preferable. The energy sequestered by the local resonators can be harvested utilizing the resonator’s mass as the multifunctional kernel for a linear electromagnetic generator. A multiphysical model is developed to predict the harvested electric voltage and power from the AMB and validated using proof-of-concept experiments. Finally, various coil placement and voltage rectification schemes are also studied using simulations to ascertain preferable design configurations.

Stability Analysis of Smart FG Sandwich Plates with Auxetic Core

As a new model, functionally graded piezoelectric (FGP) sandwich plate with negative Poisson’s ratio honeycomb core (auxetic core) is considered in this paper. Buckling analysis of the FGP sandwich plate is investigated based on a novel four-unknown shear deformation plate theory. The electrical and mechanical properties of the face layers are continuously varied through the thickness of the layers. This variation is achieved using a power law distribution in terms of the constituents volume fraction. The core layer composed of hexagonal honeycomb cells with negative Poisson’s ratio was made of a metallic material. The sandwich plate is exposed to uniaxial or biaxial compressive loads as well as electric voltage. Five stability differential equations are established based on the principle of virtual work including mechanical and electric loads. The obtained buckling load is compared with that available in the literature. Impacts of various parameters like the power law index, load parameter, external applied voltage, core thickness, boundary conditions and plate geometry on the buckling load of the smart composite plates with auxetic core are investigated. From the numerical results, one can find that the increase of electric voltage and core thickness decreases the buckling load.

Контроль дефектов в прошедшем через металл импульсном магнитном поле

Experimental dependences U (t) of electric voltage on time t, taken from an induction magnetic head (MG), moving relative to a magnetic carrier (MG) with records of the magnetic fields of defects of an aluminum object, are presented. Contact access to the surface of a metal object, above which there is a layer of air and solid dielectric in an arbitrary proportion and with a total thickness of more than 5 mm, is completely excluded. There is also no access to the rear side of the object, since it is a massive dielectric. The object with MN was exposed to a complex magnetic field pulse with a duration from 1 μs to 200 μs. The studies were carried out in a field that passed through the metal. Raster images of hidden holes with a diameter of 3 mm and 6 mm in layers of aluminum with a thickness of 0.67 mm of samples made up of layers of aluminum of different thickness and separated by layers of dielectric (air) were obtained. The thickness of the metal layers of the samples was 1.96 mm and 2.96 mm. The measurements were carried out in hard-to-reach places of the samples. The algorithm of the developed method was drawn up. The method allows to significantly increase the sensitivity and accuracy of the control of the parameters of defects and to carry out their control of areas of objects where control by other methods is impossible.