Voltage Response Research Articles

Approximate analytical solutions of the 1:3 internal resonance response of piezoelectric energy harvester considering two types of coupled frequency components

The 1:3 internal resonance effect in the L-shaped piezoelectric vibration energy harvester leads to an expanded frequency band for energy harvesting and better matching of external excitation frequency in the environment. The electromechanical-coupled governing equations for this vibration energy harvester have been validated in our previous work (Nie et al., 2019). The effect of load resistance on the energy harvester’s natural frequency and damping ratio is addressed. The quadratic and cubic nonlinearities in this system leads to two types of coupled frequency components appear, they ultimately affect the approximate solution of the voltage response. The method of multiple scales is used to derive the two types of coupled frequency components of the system along with their contribution to the output responses. The revised approximate analytical solutions of the output responses are then presented. The system’s stability is assessed through the Jacobi matrix of modulation equations. The nonlinear softening phenomenon that favors the broadening of the bandwidth of the energy harvester is analyzed. The vibration patterns in regions with nonlinear softening and non-softening behavior are investigated through frequency spectra, phase trajectories, and Poincaré cross-sections. The findings reveal that the load resistance significantly affects the damping ratio of the harvester. Inclusion of quadratic and cubic nonlinearities results in three frequency components in the output responses spectrum, with an approximate ratio of 1:2:3. Two types of coupled frequency components appeared in the spectrum of the system’s output responses. The contribution of coupled frequency components to the output response proves crucial, and the revised approximate solutions are in good agreement with that of numerical solutions. The output responses are significantly affected by the initial conditions in the nonlinear softening region, the large and small initial conditions yield solutions in the upper and lower branches, respectively.

Polymer Nanocomposite Sensors with Improved Piezoelectric Properties through Additive Manufacturing.

Additive manufacturing (AM) technology has recently seen increased utilization due to its versatility in using functional materials, offering a new pathway for next-generation conformal electronics in the smart sensor field. However, the limited availability of polymer-based ultraviolet (UV)-curable materials with enhanced piezoelectric properties necessitates the development of a tailorable process suitable for 3D printing. This paper investigates the structural, thermal, rheological, mechanical, and piezoelectric properties of a newly developed sensor resin material. The polymer resin is based on polyvinylidene fluoride (PVDF) as a matrix, mixed with constituents enabling UV curability, and boron nitride nanotubes (BNNTs) are added to form a nanocomposite resin. The results demonstrate the successful micro-scale printability of the developed polymer and nanocomposite resins using a liquid crystal display (LCD)-based 3D printer. Additionally, incorporating BNNTs into the polymer matrix enhanced the piezoelectric properties, with an increase in the voltage response by up to 50.13%. This work provides new insights for the development of 3D printable flexible sensor devices and energy harvesting systems.

Broadband Janus-Helmholtz transducer with various liquid cavity resonances

To enhance the radiation capacity of the Janus-Helmholtz transducer (JHT) and achieve a broadband transmitting response, an asymmetric dual-cavity JHT is proposed and a broadband symmetric multi-cavity JHT design is introduced. Firstly, the vibration characteristics of the cylindrical liquid cavity are analyzed and two liquid cavities with different dimensions are utilized to construct the asymmetric dual-cavity JHT. The operating principles of both the typical JHT and the asymmetric dual-cavity JHT are revealed. Furthermore, an equivalent circuit model (ECM) for the asymmetric dual-cavity JHT is proposed by combining the ECMs of the Janus transducer and the liquid cavities. To validate the accuracy and generality of the ECM for the asymmetric dual-cavity JHT, four JHTs are fabricated and tested, and the finite element method (FEM) is also employed to predict their electroacoustic performance. The admittance obtained from ECM, FEM and experiment (EXPT) exhibit good agreement. Additionally, the radial transmitting voltage response (rTVR) calculated by FEM aligns well with the experimental results. Experimental results demonstrate that the asymmetric dual-cavity JHT, compared to its typical counterpart of the same dimensions, exhibits a significantly increased rTVR within the low-frequency band. Moreover, the directivity of the typical JHT and the asymmetric dual-cavity JHT are compared by FEM and the causes of radial response fluctuations in the asymmetric dual-cavity JHT are analyzed. Finally, a symmetric multi-cavity JHT with a lower resonant frequency and a wider operating bandwidth is designed through FEM, verifying the effectiveness of the multi-mode coupling design principle. The ECM for the dual-cavity JHT offers valuable theoretical support for optimizing JHT designs and the symmetric multi-cavity JHT design serves as inspirations for modifying resonant frequency, enhancing emission capability and advancing operating bandwidth of the JHTs.

Laser-induced transverse voltage effect in c-axis inclined La x Sr1−x TiO3 thin films prepared by MOCVD

Light and thermal detectors based on the laser-induced transverse voltage (LITV) effect have garnered significant interest for their rapid and broad spectral response. In this study, we prepared the La-doped SrTiO3 (STO) epitaxial thin films on the 12° inclined single crystal LaAlO3 (LAO) (100) substrates using our home-designed metal–organic chemical vapor deposition system. Under the illumination of a 248 nm laser, the LITV signals of La x Sr1−x TiO3 films were observed and showed dependence on the La doping level, which can be explained by the changes in the light absorption coefficient, thermal conductivity, and optical penetration depth. The optimized LITV signal was observed with a peak voltage of 23.25 V and a decay time of 106 ns under the laser power density of 1.0 mJ mm−2. The high peak voltage and fast response time of La x Sr1−x TiO3 show great potential in the field of light and thermal detection.

Experimental analysis and safety assessment of thermal runaway behavior in lithium iron phosphate batteries under mechanical abuse

Mechanical abuse can lead to internal short circuits and thermal runaway in lithium-ion batteries, causing severe harm. Therefore, this paper systematically investigates the thermal runaway behavior and safety assessment of lithium iron phosphate (LFP) batteries under mechanical abuse through experimental research. Mechanical abuse experiments are conducted under different conditions and battery state of charge (SOC), capturing force, voltage, and temperature responses during failure. Subsequently, characteristic parameters of thermal runaway behavior are extracted. Further, mechanical abuse conditions are quantified, and the relationship between experimental conditions and battery characteristic parameters is analyzed. Finally, regression models for battery safety boundaries and the degree of thermal runaway risk are established. The research results indicate that the extracted characteristic parameters effectively reflect internal short circuit (ISC) and thermal runaway behaviors, and the regression models provide a robust description of the battery's safety boundaries and thermal runaway risk degree. This work sheds light on understanding thermal runaway behavior and safety assessment methods for lithium-ion cells under mechanical abuse.

Design of Solar Energy Based System Using Artificial Neural Network Controller

A key component of energy generation and the safe operation of the electrical system is solar energy. The solar energy system for producing the required voltage is presented in this paper. It is managed by an artificial neural network (ANN) controller, which performs significantly better than a conventional PI controller. It aids in lowering the system's total harmonic distortion (THD). The sole PI controller, which produces an erratic output response, is utilized in conventional wind turbines. It is swapped out in the suggested system for an ANN controller, which offers smooth voltage and current response. Two inputs and two outputs are used in the system's development. Six pulse-fired IGBTs that reduce excess voltage and current in the circuit operate this system. The MATLAB/Simulink tool was used to create the results, which were shown to be superior to traditional results. To regulate the impact of a variable power factor, an output variable load is connected. Every outcome has been validated and confirmed to be superior than traditional outcomes.

Rapid time-domain simulation of fractional capacitors with SPICE

Fractional capacitors, commonly called constant-phase elements or CPEs, are used in modeling and control applications, for example, for rechargeable batteries. Unfortunately, they are not natively supported in the well-used circuit simulator SPICE. This manuscript presents and demonstrates a modeling approach that allows users to incorporate these elements in circuits and model the response in the time domain. The novelty is that we implement for the first time a particular configuration of RC elements in parallel in a Foster-type network with SPICE in order to simulate a constant-phase element across a defined frequency range. We demonstrate that the circuit produces the required impedance spectrum in the frequency domain, and shows a power-law voltage response to a step change in current in the time domain, consistent with theory, and is able to reproduce the experimental voltage response to a complicated current profile in the time domain. The error depends on the chosen frequency limits and the number of RC branches, in addition to very small SPICE numerical errors. We are able to define an optimum circuit description that minimizes error while maintaining a short computation time. The scientific value is that the work permits rapid and accurate evaluation of the response of CPEs in the time domain, faster than other methods, using open source tools.

Diagnosis of Li-ion battery degradation based on resistive and diffusion-related transient voltage changes at early stage of discharge

Lithium-ion batteries degradation can be classified into capacity reduction and increase of the internal resistance. Accurate estimation of the degradation is important to determine the economic value and the remaining useful life of the battery. This paper proposes a method which analyzes the transient voltage response at the early stage of discharge, starting from the fully charged state. An equivalent circuit composed by a series resistance and a Warburg element is adopted to fit the transient voltage. The Warburg element is modeled as a transmission line composed by a ladder of resistances and capacitances. The method is validated with data obtained before and after aging cycles performed at 1.4 C charge and 2.0 C discharge rates, at 25 °C, 10 °C and −5 °C. The loss of cyclable lithium is deemed to be the main reason behind the battery degradation at all the tested temperatures. The dependency of the Warburg parameter to the remaining cell capacity is the same regardless of the aging temperature, suggesting that estimation of the Warburg parameter provides information about the state of health of the cell. On the other hand, the relationship between the capacity reduction and the increase of resistance has a temperature-dependent slope with low increase at lower temperatures where lithium plating is likely to occur. Accordingly, a relatively low resistance increase is deemed to be the sign of lithium plating.

Study on surface morphology and properties of biological type Ag-IPMC and its application on butterfly soft robot

Ionic Polymer Metal Composite (IPMC) is a new type of artificial muscle material. It has unique advantages such as low driving voltage, good flexibility and rapid response that make it suitable for driving soft robots. However, the high preparation cost limited its widely application. The focus of this paper is to study a low-cost and high-performance Ag-IPMC and explores its application in driving bionic butterfly robots. In addition, based on the flexible characteristic of IPMC, a bionic butterfly soft robot is designed and manufactured, and its related performance is also studied. This manuscript also has provided a reference value for the extensive diversified application of the biological IPMC.

Dielectric properties of low-temperature-grown homoepitaxial (−201) β-Ga2O3 thin film by atmospheric pressure plasma-assisted CVD

The atmospheric pressure plasma-assisted chemical vapor deposition technique has successfully demonstrated unintentionally doped (UID) Ga2O3 growth at 350 °C. This technique allows independent and homogeneous multiple nuclei growth of Ga2O3, leading to three-dimensional grain growth at a rate of ⁓0.17 μm/h. In the study of Schottky barrier diodes, the Schottky-like current (I)–voltage (V) response shows typical behavior on Ga2O3. This is a good sign at an early stage of device development on the grown sample. The extracted barrier height of ⁓2.20 eV was higher, which may be due to unintentional PtOx formation on the Ga2O3 surface. Furthermore, the extracted capacitance (C)–voltage (V) depth profiling of the effective impurity concentration was nearly flat, ⁓1.5 × 1017 cm−3, in the unintentionally doped grown film. The effective impurity concentration is comparable to the UID carrier concentration of epitaxial films fabricated using the high temperature growth technique. Therefore, low-temperature-grown homoepitaxial Ga2O3 thin films grown by atmospheric pressure-plasma-assisted chemical vapor deposition can be used in future Ga2O3-based power device applications.

Elitism-crossover barnacle mating optimization and its application to PID controller design for a buck converter

This paper presents an elitism-crossover barnacle mating optimization (ECBMO). It is an improvement of barnacle mating optimization (BMO). The original BMO suffers from local optima problem leading to a low accurate solution. A new method of offspring generation is adopted into the original BMO structure. Some features of the best-so-far solution are incorporated into the generated offspring. The accuracy performance of the proposed algorithm is tested on several IEEE functions. A statistical analysis is conducted to compare its performance over the original BMO. It is also applied to optimize proportional integral derivative (PID) parameters for controlling output voltage of a buck converter. Result of benchmark functions test shows the proposed algorithm has attained higher accuracy for all functions compared to BMO algorithm. Application on the real problem shows both algorithms control the converter voltage satisfactorily. However, the ECBMO has achieved more optimal PID parameters and leading to a better output voltage response.

Dynamic Fractional-Order Model of Proton Exchange Membrane Fuel Cell System for Sustainability Improvement

The proton exchange membrane fuel cell (PEMFC) stands at the forefront of advancing energy sustainability. Effective monitoring, control, diagnosis, and prognosis are crucial for optimizing the PEMFC system’s sustainability, necessitating a dynamic model that can capture the transient response of the PEMFC. This paper uses a dynamic fractional-order model to describe the behaviors of a stationary micro combined heat and power (mCHP) PEMFC stack. Based on the fractional-order equivalent circuit model, the applied model accurately represents the electrochemical impedance spectroscopy (EIS) and the dynamic voltage response under transient conditions. The applied model is validated through experiments on an mCHP PEMFC stack under various fault conditions. The EIS data is analyzed under different current densities and various fault conditions, including the stoichiometry of the anode and cathode, the stack temperature, and the relative humidity. The dynamic voltage response of the applied model shows good correspondence with experimental results in both phase and amplitude, thereby affirming the method’s precision and solidifying its role as a reliable tool for enhancing the sustainability and operational efficiency of PEMFC systems.

Experimental study on behaviors of lithium-ion cells experiencing internal short circuit and thermal runaway under nail penetration abuse condition

This work compared the macro-phenomenon, voltage response, surface temperature, mass loss and material characteristics of LiCoO2 (LCO), LiMn2O4 (LMO), Li(NixCoyMnz)O2 (NCM), LiFePO4 (LFP) cells with the same capacity under penetration tests. The tests provided an in-depth study on behaviors and properties of internal short circuit (ISC) and thermal runaway (TR). From the results, a feature was discovered that the parameters of different types of cells showed different tendencies when penetrated with a series of diameter nails, determined by cathode materials. The LFP cell experienced a slight ISC. Temperature rise rate and maximum temperature increased with larger diameter of nails. The NCM, LCO and LMO cells experienced a severe ISC. The maximum temperature of cells increased, however, the temperature rise rate reduced and macro-phenomena delayed and weakened with larger diameter of nails. For different type of cells, the order of ISC sensitivity was as follows: LCO > LMO > NCM > LFP. As state of charge (SOC) increased, the cells had a higher risk of TR, evidenced by higher surge current and temperature rise rate. The results of nail penetration tests at 100 % SOC indicated that the hazard of TR was arranged in the order of LCO > NCM > LMO > LFP. Due to the fragmentation of secondary particles during the extrusion of nail, the cathode composed of secondary particles suffered more damage than composed of primary particles. The research can provide support for the safety design of cells.

Magnetic coupling and amplitude truncation based bistable energy harvester

We present a two-degree-of-freedom bistable piezoelectric energy harvester (PEH) combining both magnetic coupling and amplitude truncation mechanisms to improve the electrical response when installed within compact spaces. The PEH processes a time-varying potential well and each beam has two electrical responses due to the interaction between two magnets. The collision-induced amplitude truncation behavior leads to high-frequency vibration responses, which reduces the matching impedance of the PEH. The Hamilton's principle and the Galerkin method was applied to establish the distributed parameter model for the system. By numerical calculations, the influence of the magnet distance and beam stiffness ratio on the static potential well, as well as the influence of excitation acceleration and stop gap on the voltage and power response were explored. A series of experiments were conducted to validate the voltage and power responses under sweep and fixed frequency excitations. The experimental and simulation results agree with each other. Due to the effect of magnetic coupling, the response frequency bandwidth of the cantilever beam widens by more than 7 Hz. The frequency-up effect generated by collision increases the response power of the system with the maximum of 307.8 mW at 103.6 Ω in experiments, and the combination of the two widens the impedance matching range of the system. This broadband structure with a wide impedance matching range and limited motion is more suitable for practical applications.

Experimental investigation of time-dependent electrical load effects through multipoints in-situ measurement of temperature and relative humidity of PEMFC bipolar plate under transient operation

In this study, multiple micro-relative humidity and temperature (RH/T) sensors were installed in the anode and cathode channels of a proton exchange membrane fuel cell (PEMFC) bipolar plate to simultaneously observe and analyze the variation in RH/T behaviors during transient operation. In order to simulate the acceleration and deceleration process, the electrical load was ramped from 10 to 40 A and then back to 10 A, with time intervals of 0, 2, and 5 s. The data corresponding to different acceleration/deceleration time intervals were compared and analyzed to assess the time-dependent effects of load changes. The analyzed data provide visual information, including the transient voltage response, transient behavior of temperature and water distribution, and evolution of RH/T within PEMFC. The results indicate that the acceleration and deceleration interval times significantly influence the temperature and water distribution within PEMFC during transient operation. Shorter acceleration times lead to more rapid changes in temperature and humidity within the PEMFC active area, resulting in higher transient temperature and water concentration. This finding explains why the output voltage decreases more when the load changes with a short time interval. This research enhances our understanding of transient temperature and water behavior, providing a foundation for further research and development of effective operational strategies and vehicle PEMFC designs.

On a Nonlinear Locally Resonant Metamaterial With Resistance-Inductance Shunt

Abstract Numerous recent works have established the potential of various types of metamaterials for simultaneous vibration control and energy harvesting. In this paper, we investigate a weakly nonlinear metamaterial with electromechanical (EM) local resonators coupled to a resistance-inductance shunt circuit, a system with no previous examination in the literature. An analytical solution is developed for the system, using the perturbation method of multiple scales, and validated through direct numerical integration. The resulting linear and nonlinear band structures are used for parametric analysis of the system, focusing on the effect of resonator and shunt circuit parameters on band gap formation and vibration attenuation. This band structure analysis informs further study of the system through wavepacket excitation as well as spectro-spatial analysis. The voltage response of the system is studied through spatial profiles and spectrograms to observe the effects of shunt inductance, nonlinearity, and their interactions. Results describe the impact of adding a shunted inductor, including significant changes to the band structure; multiple methods of tuning band gaps and pass bands of the system; and changes to wave propagation and voltage response. The results demonstrate the flexibility of the proposed metamaterial and its potential for both vibration control and energy harvesting, specifically compared to a previously studied system with resistance-only shunt.

Bismuth-Based Perovskite Derivates with Thermal Voltage Exceeding 40 mV/K.

Heat is an inexhaustible source of energy, and it can be exploited by thermoelectronics to produce electrical power or electrical responses. The search for a low-cost thermoelectric material that could achieve high efficiencies and can also be straightforwardly scalable has turned significant attention to the halide perovskite family. Here, we report the thermal voltage response of bismuth-based perovskite derivates and suggest a path to increase the electrical conductivity by applying chalcogenide doping. The films were produced by drop-casting or spin coating, and sulfur was introduced in the precursor solution using bismuth triethylxanthate. The physical-chemical analysis confirms the substitution. The sulfur introduction caused resistivity reduction by 2 orders of magnitude, and the thermal voltage exceeded 40 mV K-1 near 300 K in doped and undoped bismuth-based perovskite derivates. X-ray diffraction, Raman spectroscopy, and grazing-incidence wide-angle X-ray scattering were employed to confirm the structure. X-ray photoelectron spectroscopy, elemental analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were employed to study the composition and morphology of the produced thin films. UV-visible absorbance, photoluminescence, inverse photoemission, and ultraviolet photoelectron spectroscopies have been used to investigate the energy band gap.

Polyaniline and water pre-intercalated V2O5 cathodes for high-performance planar zinc-ion micro-batteries

The imperative development of high-performance planar micro-batteries featuring high-capacity electrodes and environmentally safer, cost-effective systems is crucial for powering forthcoming smart, miniaturized portable electronic devices. In alignment with this necessity, this study centers on achieving high-capacity cathode materials. This involves the pre-intercalation of polyaniline and water into V2O5 nanowires to enhance capacity, applied in conjunction with Zn anodes within a planar device structure to boost charge storage performance. The presented straightforward strategy is demonstrated to not only effectively increase charge storage capacities from 235 mAh/g to 384 mAh/g at 200 mA/g but also reduce the pre-activation process. Consequently, the Zn-ion micro-batteries obtained, featuring high-capacity cathodes, not only provide a substantial areal capacity of 409 μAh/cm2 but also exhibit notable peak areal energy density and power density at 306.7 μWh/cm2 and 3.44 mW/cm2, respectively. Additionally, the micro-battery demonstrates a slow self-discharge voltage response, with approximately 80 % retention even after 200 h. This work proposes an effective strategy to enhance the electrochemical performance of planar micro-batteries, a critical advancement for the development of advanced portable electronics.

Research and fabrication of bimetallic plate transducer based on finite element analysis

By enhancing the type 1–3 piezoelectric composite material, a highly sensitive hydroacoustic transducer sensitive element structure is suggested for uses in sonar systems, such as small target identification and fine imaging. A lower metal plate, a piezoelectric ceramic column array, and an upper metal plate make up the piezoelectric material structure. The resonance frequency of the bimetal plate type piezoelectric ceramic array material was theoretically analyzed, the sensitive element geometry of the bimetal plate piezoelectric material was studied using finite element simulation, the material choice for the metal plate affected the material’s performance, and the parameters of each size of the sensitive element were determined. These findings served as a guide for the production of a highly sensitive hydroacoustic transducer, as well as the structure of the piezoelectric material transducer in the water performance test. Results indicate that the structure transducer has a maximum transmit voltage response of 178 dB and a −3 dB bandwidth of approximately 25 kHz; the transducer may be efficiently tuned for a maximum receive sensitivity of −172 dB.

Frequency Propagation: Multimechanism Learning in Nonlinear Physical Networks.

We introduce frequency propagation, a learning algorithm for nonlinear physical networks. In a resistive electrical circuit with variable resistors, an activation current is applied at a set of input nodes at one frequency and an error current is applied at a set of output nodes at another frequency. The voltage response of the circuit to these boundary currents is the superposition of an activation signal and an error signal whose coefficients can be read in different frequencies of the frequency domain. Each conductance is updated proportionally to the product of the two coefficients. The learning rule is local and proved to perform gradient descent on a loss function. We argue that frequency propagation is an instance of a multimechanism learning strategy for physical networks, be it resistive, elastic, or flow networks. Multimechanism learning strategies incorporate at least two physical quantities, potentially governed by independent physical mechanisms, to act as activation and error signals in the training process. Locally available information about these two signals is then used to update the trainable parameters to perform gradient descent. We demonstrate how earlier work implementing learning via chemical signaling in flow networks (Anisetti, Scellier, etal., 2023) also falls under the rubric of multimechanism learning.