Output Performance Research Articles

High Tribo-Charge Density Composite Nanofiber Membrane for Motion Sensing and Water Wave Energy Harvesting.

Triboelectric nanogenerators (TENGs), among the most simple and efficient means to harvest mechanical energy, have great potential in renewable energy utilization. While the output performance of TENGs is still not high enough, which limits its practical application. Here, a poly(vinylidene fluoride) (PVDF)/fluorinated ethylene propylene nanoparticles (FEP NPs) porous nanofiber (PFPN) membrane with waterproof, breathable, surface superhydrophobic and high tribo-negative properties is proposed for achieving high-performance of TENGs. The PFPN-based solid-solid contact PFPN-TENG achieved an optimal electric output with a net tribo-charge density of 294µCm-2, which is 42.2% more than that of polytetrafluoroethylene (PTFE) film. The PFNP membrane can maintain the best performance with almost no attenuation after 142680 working cycles. Based on its excellent triboelectric characteristics, the PFPN membrane shows its excellent performance for self-powered body motion sensing and mechanical energy harvesting. A flexible solid-liquid contact PFPN-TENG can achieve high electrical output with an average volume power density of ≈544.1Wm-3 by harvesting water wave energy. Such excellent performance of the PFPN membrane makes it a potential candidate to promote the power density of TENGs in harvesting blue water wave energy.

Analysis of Output Performance Measures of Coating in EDM by Non-dominated Sorting using Pareto Front

Analysis of Output Performance Measures of Coating in EDM by Non-dominated Sorting using Pareto Front

Training improvement methods of ANN trajectory predictors in power systems

AbstractThis paper proposes training improvement methods of artificial neural networks (ANN) trajectory predictors. First, a dynamic power system time‐series trajectory is split into several different segments to simplify the original ANN training problem. Moreover, the time‐derivative of the trajectory is included to obtain an augmented loss function. Compared to previous studies which mainly focused on increasing the prediction accuracy, the aim of these novel techniques is to reduce the computational burden where the ANN output performance is still acceptable. The effectiveness of the developed methods is validated based on the WSCC three‐machine nine‐bus and IEEE 39‐bus system models. The mean absolute error (MAE) and trajectory prediction results are analysed, in which the numbers of neurons, hidden layers, and training epochs are constrained during the ANN training process. Rotor‐angle difference between generators and the system frequency are investigated as the dynamic trajectories of the power system models. The approaches are revealed to be effective when the ANN architecture and epochs are constrained. The MAE results can be reduced by up to 65% in the power system models depending on the ANN hyperparameters and training epochs. The ANN training results can better reflect the original trajectory as well.

Development of a rotary piezoelectric energy harvester using magnetic excitation inspired by the fan blade

This work proposes a new rotary piezoelectric energy harvester using magnetic excitation inspired by the fan blade. The configuration and operating principle of the harvester are introduced. Then, the equivalent nonlinear model of the piezoelectric beam is established based on the Euler–Bernoulli theory and the Rayleigh–Ritz method. Finite element simulation is used to obtain the vibration performance of the piezoelectric beam, and the first order natural frequency is obtained as 22.059 Hz. A prototype of the proposed harvester is developed, and a series of experiments are carried out. The effect of magnet deflection angle, magnet mass, and the number of magnets on the output performance of the harvester is studied in detail by experiments. The experimental results proved that the harvester obtained a relatively better output performance when the deflection angle of the drive magnet is 30°. In addition, the harvester generated the maximum output voltage when the rotary speed is 165 rpm, which is consistent with the simulation result. The harvester achieved an average power of 43.5 mW when the resistance was 130 kΩ under the rotary speed of 165 rpm. The output power can satisfy the power consumption of low-power electronic devices, such as LEDs, calculators, and electronic meters.

Model for investigating cathode dual-population microfluidic microbial fuel cells

Microfluidic microbial fuel cells (MMFC) are one of the most promising power sources. However, due to the lack of clarity in the internal operating mechanism, the output performance is suboptimal. Thus, a comprehensive two-dimensional cathode dual-population model is developed to gain deeper insights into internal workings. Based on verifying the accuracy of the model, the influence of temperature, ionic strength, and spacing of electrode on the performance and microbial growth of MMFC are explored. The finding reveal a nonlinear trend in the performance of MMFC at temperatures of 293.15 K and 313.15 K. Furthermore, the impact of electrode spacing and ionic strength on the performance of MMFC is examined, thereby emphasizing the applicability in experimental research and numerical simulation. This study provided insights into the operating mechanism of dual-population microbial microfluidic fuel cells.

Modeling and application research of absolute gravimeter driven by a V-shaped linear ultrasonic motor.

A V-shaped linear ultrasonic motor (LUSM), used as a driving element for the absolute gravimeter, generates structural vibrations when the motor starts and stops, which interfere with and influence the accurate measurement of the absolute gravimeter. In order to address this problem and provide better stability and measurement accuracy, this paper designs a fuzzy proportional integral differential (PID) controller and realizes the drive control of the motor on a field programmable gate array (FPGA) using the Verilog hardware description language (HDL). The advantages of the proposed controller are verified by comparing the simulation results with those of the traditional PID controller. First, the technical index of the LUSM as the driving element is studied through theoretical analysis based on the operation mechanism of the absolute gravimeter. Then, the relationship between the output performance and the input parameters (excitation voltage, preload, and driving frequency) of the motor in a vacuum/natural environment is experimentally investigated. Finally, an experimental system is constructed, and experiments are conducted to measure the acceleration of gravity and compare with the test results of the habitual FG-5 absolute gravimeter. The experimental results show that the output performance of the V-shaped LUSM meets the requirements of the driving element of the absolute gravimeter. The combination of the two control methods can realize the repeatable and stable operation of the system. Moreover, the motor with a mass of only 92g can output force directly without transmission components. The complexity and the weight of the system are significantly reduced, which has certain advantages.

Low-voltage DC-DC off-grid PV system: various irradiance studies

The off-grid photovoltaic (OGPV) system, also referred to as a stand-alone power system, generates electricity from solar energy independently of the main electricity grid. However, photovoltaic (PV) modules face limitations in consistently providing the necessary voltage. Thus, a DC-DC converter is employed to adjust the voltage to match the requirements of the load. This paper proposes a detailed analysis of irradiance patterns resembling in-lab and real-world conditions to address the challenge of selecting the optimal DC-DC OGPV system capable of functioning effectively under standard test condition (STC) and dynamic test condition (DTC), respectively. Three proposed irradiance analyses, tailored to different environmental scenarios, aim to identify output performances for DC-DC OGPV system which are aligning with standards set by the International Electrotechnical Commission (IEC) 61727. The DC-DC OGPV system is simulated using MATLAB Simulink. Furthermore, comparative studies involving different PV module types and several switching techniques (pulse generator and maximum power point tracking or MPPT implementations), where findings are instrumental in advancing the development and projection planning for medium to high-voltage OGPV systems, contributing to the global initiative for accessible and sustainable energy solutions aligned with sustainable development goal (SDG 7).

Performance optimization of MoS2-doped PVDF-HFP nanofiber triboelectric nanogenerator as sensing technology for smart cities

The greatest potential for resolving today's energy crisis caused by social globalization is the invention of nanogenerators. Triboelectric nanogenerators (TENGs) are among the most advanced and promising technologies because of their simple and affordable device design. TENGs can capture mechanical energy from our surroundings. Herein, we fabricated a TENG device using a novel MoS2-doped poly (vinylidene fluoride-co hexafluoropropylene) (PVDF-HFP) electrospun fiber and amino-functionalized reduced graphene oxide-doped polyurethane (PU/A-rGO) electrospun fiber as tribonegative and tribopositive materials, respectively. The concentration of MoS2 nanofiller doping in PVDF-HFP fiber was varied to study and optimize the output performance of TENG. The highest open circuit potential of 150 V, short circuit current of 4.2 μA, and power density of 0.17 Wm−2 are displayed by the 3 wt% MoS2 filled PVDF-HFP and 2 wt% A-rGO-doped PU-based (3PHM-PU/2A-rGO) TENG device. The surface potential of the 3PHM fiber showed a saturation reading of -832 V, which is 4.3 times greater than that of 0PHM fiber (0PHM -190 V). Lastly, the TENG device is used to demonstrate practical and instantaneous applications like LED lighting and the operation of portable electronics by harvesting mechanical energy. Furthermore, the TENG device shows a lot of potential in using smart streetlight sensor applications.

Preparation and performance study of three-dimensional interconnected structured electrodes with lamellar connections

In this study, we developed an innovative strategy to fabricate perovskite oxide powder with 12.356 m2/g of specific surface area. Polyacrylamide hydrogel was used as a template to prepare Sm0.5Sr0.5CoO3-δ (SSC) powders with lamellar structure. The three-dimensional interconnected structured SSC electrodes with lamellar connections were fabricate using screen printing method. As a result, the oxygen vacancy concentration of the SSC powder obtained by the polyacrylamide template method was 0.625 and 0.642 at 650 °C and 700 °C respectively. At 650°C, the polarization resistance value was 0.11 Ω cm2 for the novel SSC-PAM-V cathode. Compared with the SSC-SG cathode, the polarization resistance and activation energy of SSC-PAM-V were reduced by 50 % and 6.9 %, respectively. Furthermore, in a single cell with SSC-PAM-V electrodes, we achieved a maximum power density of 935 and 1243 mW cm−2 at 650 °C and 700 °C under wet H2 conditions, demonstrating good electrochemical output performance. The layered porous electrode was not only suitable for the diffusion of oxygen, but also for increasing the reactive active sites. The proposed powder prepared with polyacrylamide hydrogel as template, was not only suitable for the optimization of perovskite oxide, but also for the application in other types of catalysis, providing the potential for improving the electro-catalytic activity of perovskite electrodes.

Effect of incomplete line defect size on energy localization and harvesting in phononic crystals.

The high electrical output performance of the phononic crystal (PnC)-based piezoelectric energy harvesting (PEH) system is of great research value in self-powered applications. This work presents the effect of incomplete line defect size on elastic wave energy localization and harvesting. The results show that for a given 7 × 5 supercell when the incomplete line defect reaches the second to sixth layer, the energy localization and harvesting performance show a changing trend of first increasing and then decreasing; when the incomplete line defect reaches the 4th, 5th, 3rd, 2nd, and 6th layers of the supercell, respectively, the performance of PEH systems shows a trend from large to small. Among them, when the incomplete line defect reaches the fourth layer of the supercell, the performance of the PEH system is optimal, and the maximum output voltage and the maximum output electric power are 22.54 V and 12.78 mW, respectively. This work provides valuable insights for improving the performance of PEH devices by using the PnC with incomplete line defects.

Yarn‐to‐Yarn Surface Area and Roughness as Structural Engineering Tools for Optimizing the Electrical Output of Triboelectric Nanogenerators: Geometrical and Experimental Verification

AbstractThis paper investigates the performance of woven triboelectric nanogenerators (W‐TENGs) fabricated with different fabric patterns, specifically plain, twill, and hopsack weaves, using wool and polyester yarns. It is intended to enhance the electrical output and efficiency of W‐TENGs for potential applications in wearable electronics by optimizing the weaving pattern. Results indicate that W‐TENGs with twill 2/2 and hopsack 2/2 patterns exhibit superior electrical outputs, attributed to their higher contact surface area and roughness. The twill 2/2 pattern demonstrates the highest electrical output, generating an open‐circuit voltage of 4.7 V, a short‐circuit current of 4 µA, and a transferred charge of 0.35 µC. This study also highlights the critical role of surface area and dielectric material roughness in determining the output performance of triboelectric structures. A theoretical model is developed to calculate the real contact surface area of the woven fabrics with different patterns. Statistical analysis reveals significant relationships between surface roughness parameters and electrical performance. Dynamic testing under varying contact forces and frequencies demonstrates the practical applicability and robustness of the W‐TENGs. Furthermore, the devices exhibit excellent durability, maintaining stable performance over extended periods. This research provides new insights into fabric design strategies for optimizing energy harvesting in wearable devices.

A novel flow channel inspired by classical mathematical function: Enhancing output performance and low-grade heat recovery efficiency of thermal regeneration ammonia-based flow battery

Thermal Regeneration Ammonia-based Flow Battery (TRAFB) faces significant challenges in enhancing its output performance and low-grade waste heat recovery efficiency due to limitations in mass transfer and an incomplete understanding of the mass transfer mechanism. To address these issues, this study innovatively introduces a novel sinusoidal wave flow channel (SWFC), which is inspired by the classic mathematical function. The impact of the SWFC on TRAFB performance is thoroughly discussed and compared in detail with the conventional straight flow channel (SFC). Most importantly, this work unveils for the first time the distribution mechanism of the three mass transfer modes in TRAFB, which are convection, diffusion, and electrophoretic mass transfer. The main findings reveal that the mass transfer performance of TRAFB is primarily governed by convection and diffusion, with electrophoretic mass transfer playing a minimal role, and there is a threshold of current density beyond which the dominant mass transfer mechanism transitions from convection to diffusion. The unique design of the SWFC, which induces the Venturi effect, significantly enhances the overall mass transfer performance of the TRAFB due to the distinct local acceleration, achieving a remarkable enhancement in flux of up to 118.48 times. By optimizing the amplitude and period, the battery's output performance can be further enhanced, with the maximum peak power achieved by the SWFC with an amplitude of 0.8 mm and a period of 0.5π, which is 95.63 % over the SFC. Notably, the SWFC also excels in improving the thermoelectric conversion efficiency, particularly at high current densities, achieving an enhancement of up to 9.81 times.

A Triboelectric Nanogenerator Based on TPU/PLA for Basketball Motion Monitoring.

Sports monitoring equipment that integrates advanced sensing technology has attracted widespread attention in recent years. Hence, we proposed a TPU/PLA 3D printing film triboelectric nanogenerator (TP-TENG) to monitor basketball player posture for training effectiveness evaluation. By introducing carbon fibers, TPU/PLA/Carbon film with conductive and positive triboelectric properties was prepared. According to results, the peak power density is 58.38 mW m-2 when the load resistance of 30 MΩ is matched. Nevertheless, when TP-TENG encounters wrinkles and continues to work for a period of time, its output performance will tend to stabilize. And the open-circuit voltage (VOC), transfer charge (QSC), and short-circuit current (ISC) increase to 91 %, 92 %, and 92 %, respectively, almost the same as their original values. Furthermore, the TP-TENG sensor can recognize human posture in different basketball motion posture, including skipping, squatting, walking, running. This work can help to promote the application of 3D printing TENG in basketball sports monitoring.

Triboelectric Nanogenerator-Embedded Intelligent Self-Aligning Roller Bearing with the Capability of Self-Sensing, Monitoring, and Fault Diagnosis.

Monitoring the dynamic behaviors of self-aligning roller bearings (SABs) is vital to guarantee the stability of various mechanical systems. This study presents a novel self-powered, intelligent, and self-aligning roller bearing (I-SAB) with which to monitor rotational speeds and bias angles; it also has an application in fault diagnosis. The designed I-SAB is compactly embedded with a novel sweep-type triboelectric nanogenerator (TENG). The TENG is realized within the proposed I-SAB using a comb-finger electrode pair and a flannelette triboelectric layer. A floating, sweeping, and freestanding mode is utilized, which can prevent collisions and considerably enhance the operational life of the embedded TENG. Experiments are subsequently conducted to optimize the output performance and sensing sensitivity of the proposed I-SAB. The results of a speed-sensing experiment show that the characteristic frequencies of triboelectric current and voltage signals are both perfectly proportional to the rotational speed, indicating that the designed I-SAB has the self-sensing capability for rotational speed. Additionally, as both the bias angle and rotational speed of the SAB increase, the envelope amplitudes of the triboelectric voltage signals generated by the I-SAB rise at a rate of 0.0057 V·deg-1·rpm-1. To further demonstrate the effectiveness of the triboelectric signals emitted from the designed I-SAB in terms of self-powered fault diagnosis, a Multi-Scale Discrimination Network (MSDN), based on the ResNet18 architecture, is proposed in order to classify the various fault conditions of the SAB. Using the triboelectric voltage and current signals emitted from the designed I-SAB as inputs, the proposed MSDN model yields excellent average diagnosis accuracies of 99.8% and 99.1%, respectively, indicating its potential for self-powered fault diagnosis.

Flexible Silk Fibroin-Based Triboelectric Nanogenerators with Thermal Management Capabilities for Temperature Regulation and Self-Powered Monitoring.

Flexible triboelectric nanogenerators (TENGs) are highly advantageous for human-centered monitoring due to their self-sustaining energy and high output performance. However, temperature fluctuations that limit thermal comfort have hindered their practical advancement. In this study, flexible titanium dioxide-silk fibroin@phase change microcapsule nanofiber films (TiO2-SF@PCM NFs) were successfully developed using an efficient electro-blown spinning (EBS) technique, with exceptional triboelectric output and superior temperature regulation capabilities. Our design achieved cooling effects of approximately 10 °C and provided thermal insulation of about 2.2 °C. Notably, applying the TiO2-SF@PCM NFs to a model car produced an impressive cooling effect of 22 °C. Furthermore, a single-electrode triboelectric sensor based on TiO2-SF@PCM NFs achieved a peak output power of ∼272 μW/m2 and exceptional stability over 1000 output cycles. This study presents a promising strategy for the scalable production of flexible composite nanofiber films, effective in both temperature regulation and self-powered monitoring, highlighting their potential for use as thermal comfort sensors.

Flexible Triboelectric Nanogenerators Based on Cadmium Metal-Organic Framework/Eethyl Cellulose Composites as Energy Harvesters for Selective Photoinduced Bromination Reaction.

The fabrication of self-driven systems with flexibility and tunable output for organic photoinduction is highly desirable but challenging. In this study, a 3D cadmium metal-organic framework (Cd-MOF) is synthesized and used as a filler for ethyl cellulose (EC) to create mechanically durable and flexible Cd-MOF@EC composite films. Due to its well-established platform with periodically precise structure nature, the outputs of Cd-MOF-based TENG are much higher than those of ligand-based TENGs. Furthermore, composite films with different doping ratios of Cd-MOF are employed to assemble Cd-MOF@EC-based triboelectric nanogenerators (TENGs). The results reveal that a doping ratio of 10 wt.% Cd-MOF in Cd-MOF@EC provides the highest TENG output. Subsequently, a flexible 10 wt.% Cd-MOF@EC-based TENG (FCEC-TENG), working in the contact-separation model, is constructed to harvest mechanical energy from the human body, demonstrating excellent output performance and stability. The energy harvested from FCEC-TENG can directly illuminate 14 commercial white light-emitting diodes (LEDs), providing visible light for the photoinduction of the bromination reaction, and generating bromide with good yield and tolerance. This study presents an effective method for constructing flexible MOF-based TENG for self-powered photoinduced organic transformation systems.

Nonlinear dynamics analysis of A quad-stable electromagnetic energy harvester

This paper constructs a quad-stable system using magnets and inclined springs, and derives the magnetic force between the magnets based on the magnetic dipole hypothesis. Using the Lagrange principle, the dynamic equations of this quad-stable electromagnetic energy harvester (QEEH) are obtained. A detailed parameter analysis of the system's potential energy and restoring force is conducted, and the bifurcation of equilibrium points and dynamic bifurcation behavior under different parameters are explored. To more accurately obtain the resonant characteristics of the system, a higher-order Taylor expansion is used to expand the restoring force, noting the presence of quadratic and quartic nonlinear terms. By employing the multiscale method, an approximate solution at the equilibrium point of the QEEH system is obtained, and the amplitude-frequency characteristics of the system under different parameter conditions are studied. Experimental validation demonstrates the voltage output performance of the harvester under various parameter settings.

A numerical simulation of a novel self-powered implantable respiration sensor based on a triboelectric nanogenerator for medical applications

Abstract The breathing rate is utilized as a reliable indicator in many cases to predict and diagnose respiratory diseases as well as the respiratory dysfunction caused by diseases such as the cystic fibrosis. Therefore, in this study, a self-powered implantable respiration sensor based on a contact-separation mode triboelectric nanogenerator (TENG) was designed to monitor the respiratory rates by sensing the variation of the diaphragm muscle. For this purpose, a polytetrafluoroethylene film with a thickness of 160 μm and a nylon film with a thickness of 180 μm are employed as the negative and positive triboelectric materials. Two copper layer each with a thickness of 100 μm are placed on the outer surfaces of the triboelectric layers as the conducting electrodes. In order to uniformly deform the moving plate of the TENG, it is rigidly attached to the center of the diaphragm through a silicon mechanical coupling element with dimensions of 80 x 80 μm2. The pressure caused by breathing on the diaphragm muscle, which is in the range of 266-666 Pa, is applied to the center of the device diaphragm. The effect of various parameters including external pressure, frequency and surface charge density on the output performance of the device is also investigated. It is evident that higher external pressure results in intensive deformations of the moving plate of the TENG, leading to a more significant energy conversion efficiency of the device. Similarly, increasing the surface charge density causes an increase in all electrical output parameters. Moreover, the device achieves an output power of 0.209 nW at a load resistance of 20 GΩ by applying a pressure of 666 Pa at a frequency of 0.24 Hz. All the results demonstrate the potential of the new proposed sensor for detecting and monitoring real-time respiratory rates with high sensitivity and clinical applications.

Effect of adding ionic liquid into polydimethylsiloxane on the output performance of triboelectric nanogenerator

Abstract Adding 1-butyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)imide (BMIM-TFSI), an ionic liquid, to polydimethylsiloxane (PDMS) films significantly enhances the output of triboelectric nanogenerators (TENGs). In a TENG using contact and separation between the composite film and an aluminum (Al) plate, incorporating 0.1 vol.% of BMIM-TFSI more than doubled the output voltage was achieved compared to a pure PDMS film. To understand the cause of this improvement, composition analysis around the surface of the composite polymer film was conducted before and after tapping. We found that BMIM-TFSI molecules segregated around the surface after tapping. It is considered that the polarization of the BMIM-TFSI molecules enhances the output performance of TENGs by superimposing on the surface charges generated at the PDMS/Al interface.

Some measures to enhance the energy output performances of triboelectric nanogenerators

Abstract Triboelectric nanogenerators (TENGs) have been developed as innovative devices for harvesting various forms of mechanical energy generated by our bodies and surroundings, which provide green and sustainable power for increasingly miniaturized and mobile electronics, especially wearables. In this article, the largest possible output energy per cycle of a TENG in the two basic working modes, namely, the vertical contact-separation (CS) mode and the contact-sliding (LS) mode, is analyzed and the energy collected by a capacitor is tested. It is found that more energy output and collected from a vertical CS mode TENG than that from a LS mode TENG with the same size and triboelectric layer materials when the size and displacement range of the TENG are suitable for a wearable energy harvesting device. In order to improve the energy output of a TENG, three methods have been proposed to increase its surface charge density, such as adding a BaTiO3 film or a polydimethylsiloxane (PDMS)-BaTiO3 composite film between the triboelectric layer and the metal electrode, and using a PDMS-BaTiO3 composite film as a negative triboelectric layer, and corresponding TENGs are fabricated for experimental testing. These measures have effectively enhanced the output of the TENGs.