Electrical Behavior Research Articles

A nonlinear and asymmetric monostable compliant ortho-planar spring piezoelectric vibrational energy harvester using a H-I structure

This paper proposes a compliant ortho-planar spring piezoelectric vibrational energy harvester (COPS-PVEH) using a H-I structure that exploits a nonlinearity and an asymmetric mono-stability to enhance the bandwidth of the device. The main structure is based on a double clamped beam (I-structure) coupled with four cantilever beams (H-structure) and an ortho-planar spring in the centre of the I-structure. Finite element analysis (FEA), analytical modelling, and experimentation were performed to analyse the dynamical and electrical behaviour of the harvester. The device was fabricated using polylactide (PLA). Six bimorph PZT-5H piezoelectric materials, electrically connected in parallel, were used as piezoelectric generators. The device was tested using an optimum load resistor of 90 kΩ under sinusoidal and sine sweep excitation in the gravity (vertical) direction. The pre-load (due to gravitation) causes a softening nonlinearity and an asymmetric mono-stability in the potential energy function. The results show that multiple peaks are observed in the output voltage of the harvester in the FEA, analytical modelling, and experimentation under harmonic excitation in the sub 15 Hz frequency range. Furthermore, analytical modelling and experimentation exhibit softening nonlinearity and chaotic behaviour, reaching a maximum amplitude power of 1.01 mW (at 8.3 Hz) and 1.07 mW (at 9.5 Hz) respectively under sine sweep excitation (amplitude of 0.6 g (g = 9.81 m/s2)). Experimentally, the harvester also generates an average power greater than 46 µW with a 6.8 Hz bandwidth under the same excitation. The softening nonlinearity and asymmetric mono-stability enhance the bandwidth of the harvester in the low frequency region where most broadband ambient vibrations are available in practical environments.

Electric vehicle charging station demand prediction model deploying data slotting

Accurate prediction of energy requirement at charging station is essential for optimizing infrastructure usage, ensuring grid stability, and minimizing operational cost. Literatures suggest deployment of machine learning techniques to forecast the station demand. One major challenge associated with development of machine learning models is the inherent uncertainty in electric vehicle charging behaviour that includes variations in charging patterns, user preferences, and vehicle types. The conventional pre-processing techniques fail to dislodge nonlinearities and highly random patterns that include very low or zero-charging. Employing such techniques affects the model's forecast accuracy. This article performs data-slotting during pre-processing stage and then selects the best among 1-h, 2-h, 3-h and 4-h slots, to frame the feature vectors. The 4-h data with minimum variance is suggested to frame the dataset. Four distinct datasets, comprising different combination of average and total demands as predictor and response respectively are considered. The created dataset is deployed in Random Forest, Categorical Boosting, Extreme Gradient Boosting and Light Gradient Boosting models. The article recommends Categorical Boosting Regression model with least mean absolute error, mean square error and root mean square error of 0.0726, 0.0112, and 0.1059 respectively. Furthermore, the use of feature vector comprising of aggregated load for prescribed slots and the response representing the aggregated demand is observed to provide the least prediction error by the suggested model. The suggested model fed by the proposed feature vector offers significant advantage to charging station operator by enhancing the operational efficiency while performing resource and cost management with strategic planning.

Damage sensing in multi-functional nanocomposite polymer bonded energetics with embedded multi-walled carbon nanotube sensing networks

Abstract This experimental investigation evaluates the strain and damage sensing abilities of multi-walled carbon nanotube (MWCNT) networks embedded in the binder phase of polymer-bonded energetics (PBEs). PBEs are a special class of particulate composite materials that consist of energetic crystals bound by a polymer matrix, wherein the polymer matrix serves to maintain the composite’s shape and form. The structural health monitoring (SHM) approach presented in this work exploits the piezoresistive properties of the distributed MWCNT networks. Major challenges faced during such implementation include the low binder concentrations of PBEs, the presence of conductive/non-conductive particulate phases, the high degree of heterogeneity in the PBE microstructure, and achieving the optimal MWCNT dispersion. In this study, ammonium perchlorate (AP) crystals as the oxidizer, Aluminum grains as the metallic fuel, and Polydimethylsiloxane (PDMS) as the binder are used as the constituents for fabricating PBEs. To study the effect of each constituent on the MWCNT network’s SHM abilities, various materials systems are comprehensively studied: MWCNT/PDMS materials are first evaluated to study the binder’s electromechanical response, followed by AP/MWCNT/PDMS to assess the impact of AP addition, and finally, AP/AL/MWCNT/PDMS to evaluate the impact of adding conductive aluminum grains. Compression samples (ASTM D695) were fabricated and subjected to monotonic compression. Electrical resistance is recorded in conjunction with the mechanical test via an LCR meter. Gauge factors relating to the change in normalized resistance to applied strain are calculated to quantify the electromechanical response. MWCNT dispersions and mechanical failure modes are analyzed via scanning electron microscopy imaging of the fracture surfaces. Correlations between the electrical behavior in response to the mechanical behavior are presented, and possible mechanisms that influence the electromechanical behavior are discussed. The results presented herein demonstrate the successful ability of MWCNT networks as SHM sensors capable of real-time strain and damage assessment of PBEs.

Effects of annealing and cold rolling on microstructural features, magnetic properties, tensile behavior and electrical resistance of FeCoNi(MnAl)x high entropy alloys

In this study, the microstructure, magnetic properties, and tensile behavior of high entropy alloys of FeCoNi(MnAl)x (x = 0–0.6, in molar ratios) were investigated after casting, cold rolling and annealing. X-ray diffractometry (XRD), field emission scanning electron microscope (FE-SEM), vibrating sample magnetometer (VSM), and also tensile tests were used to evaluate phase formation, microstructure, magnetic behavior and tensile properties of the samples, respectively. The results showed that as the indices of x value increase to 0.6, crystallographic structures transform from FCC to FCC + BCC. This in turn decreased the magnetic saturation of FeCoNi(MnAl)0.6 from 151 to 36 emu/g. Increasing x to 0.6, also raised the values of Hc from 3 to 16 Oe. This behavior was also observed in annealed and cold rolled alloys. Annealing treatment also released the residual stresses and resulted in reduction of Hc values. However, the highest values of Hc was observed in cold rolled samples which ranged from 5 to 25 Oe. The tensile strength of cold rolled and annealed alloys for x values of 0, 0.2, and 0.4, were 510, 635, and 910 Mpa, respectively. Furthermore, the electrical resistance augmented monotonously with an increasing value of x. It is therefore concluded that cold rolled and annealed high entropy alloys of FeCoNi(AlMn)x can present a variety combinations of tensile, magnetic, and electrical behavior when compared to other soft magnetic materials.

Correlation Effect on Different Temperature-Humidity Range of Highly Thermal GNP/AG/ SA Conductive Ink

The study evaluates how the resistivity and properties of the material change in response to environmental factors such as temperature and humidity, and how these changes impact its performance in various applications. In order to develop a highly thermal graphene hybridization conductive ink, a new formulation of conductive ink was formulated using graphene nanoplatelet (GNP), silver flake (Ag), and silver acetate (SA) as conductive fillers mixed with organic solvents. The batch of chemicals was converted into a powder by undergoing sonication and stirring to create a powdery state. The powder was then treated with organic solvents, specifically 1-butanol and terpineol, and mixed using a thinky mixer to form a paste. The GNP/Ag/SA hybrid conductive ink paste was then printed on copper substrates using a mesh stencil and was cured at 250°C for 1 hour. Cyclic testing had been conducted using a cyclic bending test machine and a cyclic torsion test machine in a heat chamber with different temperature-humidity. The new formulation then was characterized base on the electrical and mechanical behaviour. After the torsion and bending tests, the GNP/Ag/SA hybrid conductive ink formulation reliability was evaluated. GNP/Ag/SA hybrid conductive ink room temperature baseline and GNP/Ag/SA hybrid conductive ink after given different temperature-humidity were compared in terms of electrical and mechanical properties. Both cyclic bending and torsion testing results showed an increasing value of resistance and resistivity with every progress of bending and torsion cycle, which displays a clear trend. The results indicate that the average resistance values at all sample points either stay constant or decrease with the increasing temperature. This observation suggests that the ink's electrical conductivity remains rather stable as the temperature increases. Thus, even with rising temperatures, the ink's electrical conductivity remains stable, indicating the ink's capacity to preserve its integrity and structural qualities within a defined temperature range. Future research should focus on improving the adhesion, stability and reliability of stretchable conductive inks under various temperature and humidity conditions.

Advanced sensor performance: Investigating complexities of electrical resistance relaxation behavior in piezoresistive materials

Advanced sensor performance: Investigating complexities of electrical resistance relaxation behavior in piezoresistive materials

Enhanced Schottky barrier engineering in silver-doped TiO2/p-Si heterojunctions: Insights into electrical behavior and charge carrier dynamics

Heterojunctions were fabricated through the deposition of silver-doped Titanium dioxide (Ag–TiO2) onto p-type crystalline silicon, employing the sol-gel technique. Electrical characterization was conducted with varying Ag concentrations. The investigation revealed that the Schottky barriers at each interface (Ag/TiO2 and Si/Ag), along with the built-in potential at the TiO2/p-Si junction, increase proportionally with the Ag concentration. This observed trend was attributed to the reduction in the TiO2 bandgap due to Ag incorporation, resulting in a concurrent shift in both valence and conduction bands. Consequently, there is a growth of the conduction energy discontinuity and a reduction in the valence one, facilitating hole diffusion while impeding electron transfer across the depletion layer. Furthermore, the introduction of Ag leads to a decrease in both electron and hole concentrations. However, Ag incorporation within the TiO2 matrix manifests as nanoparticles and clusters, resulting in a nonhomogeneous distribution of charge carriers across the sample. Impedance analysis indicates an increase in device resistance and a decrease in effective capacitance.

Inflated electronic and optical assessment of gC3N4/ZnO nanocomposite as a potential emissive layer material for OLED application

Organo-inorganic nanocomposite materials have been proven to be novel hybrid materials with inflated electronic and optical performance that can be tailored with the judicious selection of the building units or their combinations. Here, hydrothermal, thermal polycondensation, and ultrasonication techniques were used to synthesize pure ZnO, gC3N4, and gC3N4/ZnO with varying weights % such as 10%, 15%, 20%, and 25% of ZnO inorganic filler elements in gC3N4 matrix. The crystalline phase (hexagonal wurtzite) and crystallite size (10.0 nm, 17.6 nm, and 15.90 nm) of the synthesized materials were examined by X-ray diffractometer. The FESEM and HRTEM characterizations revealed the sheet-like gC3N4 and spherical-type ZnO nanoparticle-like microstructures of the samples. The present functional groups, corresponding vibrational frequency, chemical states, and binding energy were investigated using FTIR and XPS spectroscopic methods. Optical parameters such as optical band gap energy (Eg = 3.24 eV), Urbach energy (Eu = 0.41 eV), refractive index (n= 1.99), emission quantum yield (∼ 69.03%), and color purity of the nanocomposites were examined using UV visible and photoluminescence spectroscopic techniques. IV and Hall measurements techniques were used to determine the semiconducting parameters of the optimized sample, such as conductivity (∼62.90×10−5 S/cm), carrier mobility (∼ 44.1 cm2/Volt. Sce), carrier concentrations (∼1.825×1014 cm−3), and sheet resistance (∼1.062×103 Ω/cm2). Due to their excellent optical and electrical behavior, the nanocomposite materials were found to be fairly suitable as a potential emissive layer material for OLED applications.

Analysis of the electrical conductivity and activation energies of bismuth titanate (Bi4Ti3O12)

In this study, bismuth titanate (Bi4Ti3O12) was synthesized from pure solid compounds and structurally characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The electrical properties were evaluated by measuring the electrical conductivity of Bi4Ti3O12 at various oxygen partial pressures (pO2 = 10−5 and 10−8 atm) and temperatures (450 °C-750 °C). The electrical conductivity behavior was assessed during the heating and cooling processes. The material activation energies were determined based on the heating curve, which displayed Arrhenius-type behavior and activation energy slope changes, which could be attributed to point defects. When the temperature was increased from 450 °C to 750 °C at oxygen partial pressures pO2 = 10−5 atm, the electrical conductivity increased by about 62.9 %, whereas when the temperature decreased from 750 °C to 450 °C, the electrical conductivity was reduced by 35.95 %. The electrical behavior of Bi4Ti3O12 was analyzed by establishing its electrical conductivity and chemical activity under different oxygen partial pressures and heating-cooling conditions can allow the synthesis of materials with attractive characteristics for electronic applications.

Structural, vibrational, and electrical study of the topological insulator PbBi2Te4 at high pressure

We report a joint experimental and theoretical study of the structural, vibrational, and electric properties of the topological insulator PbBi2Te4 under compression through X-ray diffraction, Raman scattering, and electrical measurements at high pressure, which are complemented with theoretical calculations that include the analysis of the topological electron density. The internal polyhedral compressibility of the rhombohedral phase, the behavior of its Raman-active modes, the electrical behavior, and the nature of its different bonds under compression are discussed and compared with their parent binary compounds and with related ternary materials. Interestingly, PbBi2Te4 retains its topological insulating properties as far as the rhombohedral tetradymite-like phase is retained under compression, unlike other tetradymite-like compounds. In addition, PbBi2Te4 undergoes an unconventional reversible pressure-induced decomposition into the high-pressure phases of its parent binary compounds (PbTe and Bi2Te3) above 8 GPa. Finally, we discuss that the intralayer bonds in the tetradymite-like structure of PbBi2Te4 are electron-deficient multicenter bonds; i.e. bonds of the same kind as those present in its parent binary compounds, in related chalcogenides, such as SnSb2Te4, and in general in chalcogenide-based phase change materials. These unconventional bonds are intermediate between covalent and metallic bonds and provide exceptional properties to the materials.

Improved thermoelectric properties of n-type ZrNiCu0.05Sn by doping Y2O3

Half-Heusler (HH)-based alloys are promising candidates for high-temperature thermoelectric (TE) energy conversion materials due to their excellent adaptability in high-temperature regions (900 - 1100 K). However, their TE performance is greatly limited owing to the inherently high lattice thermal conductivity (κl). In this study, we introduce a synergistic strategy to reduce thermal conductivity while modifying electrical transport properties through yttrium oxide (Y2O3) dispersion. The binary NiSn compound precipitations with sub-micron dimension together with Y2O3 nanoparticles synergistically intensify the phonon scattering and enhance the seebeck coefficient (S) effectively via energy filtering effect (EFE) at hetero-interfaces, leading to a remarkable reduction in κl and a slight improvement in the power factor (PF). Consequently, upon 1.5 wt% Y2O3 introduction, the sample incorporating Y2O3 exhibits a ∼13% reduction in total thermal conductivity (κt) as compared to the HH matrix, reaching a peak ZT of 0.86 at 938 K, thereby successfully optimizing its TE performance. The presented strategy provides a feasible approach to simultaneously modulate the thermal and electrical transport behaviors to improve the TE performance of HH-based materials.

Investigation of the electrical quality and long-term stability of aluminum ground stud connections in automotive applications

The rapid advancement in the electrification of modern vehicles has led to a continuous increase in electrical consumers for various comfort and safety functions. Ground studs serve as the electrical interface between the conductive vehicle body and the onboard network. Drawn arc stud welding is an economical and established joining process for producing ground stud joints. The circuits in the onboard network are increasingly subject to greater demands regarding current-carrying capacity and long-term stability. Reliable signal and power transmission require minimal contact resistance at the electrical connection points of the ground stud system and must withstand various operating and environmental conditions over the entire service life. In this study, a ground stud made of AlMg5, with a ZnNi-coated steel cap nut was used on a 2.0 mm thick sheet of AlMg3. The electrical connection of the ground studs was made using tinned copper cable lugs and 35 mm² cables. To analyze the electrical resistance behavior in an accelerated test, the ground studs were subjected to a superimposed load with a cyclic current profile for 1008 hours under changing climatic conditions. The results show that under the chosen operational and environmental conditions, accelerated aging and intermittent resistance behavior occur. A characteristic drop in resistance during the test indicates the failure point of the electrical connection. The cause of failure can be attributed to media penetration into the electrical contact zone. A failure of the electrical connection was observed after 512 hours.

Boolean Circuits in Colloidal Mixtures of ZnO and Proteinoids.

Liquid computers use incompressible fluids for computational processes. Here, we present experimental laboratory prototypes of liquid computers using colloids composed of zinc oxide (ZnO) nanoparticles and microspheres containing thermal proteins (proteinoids). The choice of proteinoids is based on their distinctive neuron-like electrical behavior and their similarity to protocells. In addition, ZnO nanoparticles are chosen for their nontrivial electrical properties. Our research demonstrates the successful extraction of 2-, 4-, and 8-bit logic functions in ZnO proteinoid colloids. Our analysis shows that each material has a distinct set of logic functions and that the complexity of the expressions is directly related to each material present in a mixture. Our study shows that 2-, 4-, and 8-bit logic functions can be successfully extracted from ZnO proteinoid colloids. These findings provide a basis for the development of future hybrid liquid devices capable of general-purpose computing.

Theoretical and Experimental Study on Transient Electrical Behavior of Coaxial Bandpass Filter With Low-Pressure Microwave Breakdown

Theoretical and Experimental Study on Transient Electrical Behavior of Coaxial Bandpass Filter With Low-Pressure Microwave Breakdown

Electric Field Features and Charge Behavior in Oil-Pressboard Composite Insulation under Impulse Voltage

Oil-pressboard/paper insulation materials are essential in transformers for ensuring their safe and stable operation, primarily due to their roles in spatial electric field distribution and charge migration mechanisms. Current spatial distribution analyses rely on computational methods that lack empirical validation, particularly for oil-pressboard/paper composites. This study leverages the principles of the Kerr electro-optic effect to develop a rapid measurement platform for electric fields within oil-pressboard/paper insulation under impulse voltage conditions, which measures the spatial electric field characteristics using Cu-Cu and Al-Al electrodes under various scenarios: with asymmetric and symmetric pressboard coverage and different numbers of insulating paper layers. Findings indicated: (1) In asymmetric pressboard models, Cu-Cu electrodes exhibit a consistent peak electric field of approximately 16 kV/mm, while Al-Al electrodes show peak values of 18.13 kV/mm and −14.98 kV/mm. Charge density patterns are similar, with Cu-Cu at about 68 μC/m2 and Al-Al at 11.2 μC/m2 and −124.8 μC/m2. (2) Symmetric models present consistent peak electric fields and charge densities for both polarities. (3) Increasing insulating paper layers elevates electric field strengths. Both electrodes show the similar peak field of about 17 kV/mm with differing paper layers due to higher charge injection from the Al electrode. (4) Utilizing the Schottky effect and field emission principles, the study clarifies charge generation and migration mechanisms. These insights could provide a theoretical foundation for designing and verifying oil-pressboard/paper insulation structures in transformers.

Моделирование суточной вариации атмосферного электрического поля в турбулентном приземном слое

An electrodynamic model of the electric field dynamics behavior in the atmospheric surface layer due to the action of local factors is presented. The model was obtained by reducing the differential equations system of the electrode effect to the so-called total current equation, which is a second-order equation of parabolic type, considered in a two-dimensional space-time region. The total current equation allows us to connect the set of main factors influencing on the atmospheric surface layer electric field state: conduction current, turbulent current and current arising as a result of convective processes in the atmosphere with the so-called total current in the nearground layer, reflecting changes in the ionospheric potential. The described method provides significant advantages in research, since within the framework of one model it allows the formulation of various problems of electrodynamics of the surface layer and a comparative analysis of the influence on the behavior of the electric field in the surface layer of both individual factors and their combinations. Based on meteorological data at the Peak Cheget mountain station in the Elbrus region, a daily variation in the values of the turbulent diffusion coefficient was constructed. The resulting analytical dependence was used to solve the equation for the total current in the surface layer, provided that it is constant at the upper boundary of the turbulent electrode layer. Solutions obtained by the Fourier method describe the daily variation of the electric field strength depending on the degree of turbulent mixing in the atmosphere. The appearance of a time shift in daily extrema, a change in their amplitude, and the appearance of additional extrema depending on the elec-tric field values have been established. All of these effects are comparable to the global unitary variation and increase with increasing electric field.

Aspect ratio-dependent volume resistivity in unidirectional composites: Insights from electrical conduction behavior

The electrical properties of carbon fibers serve as the foundation for the multifunctional applications of carbon fiber-reinforced composite structures. In scenarios that exploit the electrical characteristics of materials, accurate estimation of electrical resistivity stands as a critical factor. This study endeavors to elucidate the electrical conduction behaviors in unidirectional composites with different fiber orientation angles (0°, 15°, 30°, 45°, 60°, 75°, and 90°) and aspect ratios, thereby deriving the volume resistivity within an arbitrary Cartesian coordinate system. Employing thermal infrared imaging technology and finite element analysis, we identified distinctive electrical conduction behaviors associated with aspect ratios in carbon fiber composite plates. Notably, a critical aspect ratio exists wherein the diagonal yarn is the only conductive path between two electrodes. Below this critical threshold, no direct conductive path exists, and current flows through the shortest distance between parallel yarns. Conversely, beyond the critical aspect ratio value, multiple yarns form conductive paths between the two electrodes. Based on the electrical conduction behavior of unidirectional composites under different angles and aspect ratios, the volume resistivity with finite boundaries was derived and examined under an arbitrary Cartesian coordinate basis.

Improving the Electrical and Mechanical Behavior of Printed Ag Microwires on Flexible Substrates by Applying High-Density Pulsed Electric Current

Improving the Electrical and Mechanical Behavior of Printed Ag Microwires on Flexible Substrates by Applying High-Density Pulsed Electric Current

Characterization of Ba–Sr thin films deposited by spray pyrolysis and fabrication of Ag/Ba–Sr/n-Si/Ag diodes

This study describes the synthesis of barium (Ba) and strontium (Sr) thin films using jet neublizer spray pyrolysis (JNSP) technology, which facilitates the fabrication of junction diodes whose structure, surface morphology, and optical properties are affected by significant water absorption. Ba–Sr films with different strontium concentrations (specifically 0, 2, 4 and 6 wt%) were further investigated to provide a better understanding of how this change affects the final diode type. The research design focuses on fabricating n-type silicon junction diodes containing barium and strontium and directly measuring and analyzing their I–V characteristics, ultimately helping elucidate these devices' electrical behavior. Among the analyzed diodes, the Ag/Ba–Sr/n-Si/Ag diode performed well in various design tests, indicating its competitiveness due to its goodness in optoelectronic devices. The ideal value (n) of a 6 wt% Ba–Sr diode is 1.77 and the barrier height (ΦB) is 0.84 eV. These results demonstrate the general future of Ba–Sr junction diode, as they not only reveal important discoveries regarding their electrical properties but also demonstrate the potential for improved performance in optoelectronic applications.

Mapping the literature of electric vehicle purchase intention and consumer behavior: A bibliometric analysis of Scopus database (2010–2023)

Mapping the literature of electric vehicle purchase intention and consumer behavior: A bibliometric analysis of Scopus database (2010–2023)