Maximum Voltage Research Articles

Computational Study of Partial Discharge Events in Electric Drives with Segmented Power Supply

The transportation industry (automobile, aerospace) is undergoing a significant shift towards higher voltage supply, to increase embedded power. Increasing the voltage can lead to an increase in the occurrence of partial discharges which have a deleterious impact on the insulators, and therefore of the system lifetime. The current study investigates two electric drives architecture, namely first a combination of a conventional motor with a single inverter and, second, a multi-Three-Phase machine based on highly coupled windings and combined with dedicated sub-inverter. The latter is based on CTAF concept (Chaîne de Traction à Alimentation Fractionnée for Electric Drive based on Segmented Power Supply). This innovative power supply concept is presented in the case study section. According to the goal of this study, a 54-turns coil is developed and modelled as the equivalent circuit, while the related lumped parameters are determined by a frequency-dependent electrostatic and magnetostatic COMSOL simulation. Subsequently, a MATLAB/SIMULINK simulation of the equivalent electric circuit enables assessing the voltage potential distribution. The latter is injected as input into the COMSOL electrostatic simulation to compute the electric field. Consequently, the maximum voltage supply without breakdown is determined, for both studied cases. The comparative study concludes that, between the two case studies analyzed, the minimum among the maximum voltage supplies without breakdown is observed in the system powered with the CTAF approach.

Boosting Energy Harvesting Performance in Piezoelectric Composites with Aligned Porosity via a Dual Structure Design Strategy.

Porous piezoelectric materials have attracted much interest in the fields of sensing and energy harvesting owing to their low dielectric constant, high piezoelectric voltage coefficient, and energy harvesting figure of merit. However, the introduction of porosity can decrease the piezoelectric coefficient, which restricts the enhancement of output current and power density. Herein, to overcome these challenges, an array-structured piezoelectric composite energy harvester with aligned porosity was constructed via a dual structure design strategy to enhance the output current and power density. Silver metal particles were introduced into a porous barium calcium zirconate titanate (BCZT) ceramic matrix as a secondary phase to regulate the dielectric, ferroelectric, and piezoelectric properties. The optimal addition of silver particles can reduce the size of ferroelectric domains, which leads to an enhanced piezoelectric coefficient and energy harvesting figure of merit. Combined with the design of the array structure, the maximum output voltage and current of the piezoelectric composite energy harvester can reach 76 V and 340 μA, respectively, with a peak power density of 0.97 mW/cm2. Furthermore, the array-structured piezoelectric energy harvester can light 40 blue LED bulbs and power commercial low-power electronic devices. This work provides a strategy to boost the output current and power density of porous piezoelectric materials via a micro-macro structure design strategy for energy harvesting applications.

Hierarchical rGO‐Based Triboelectric Sensors Enable Motion Monitoring and Trajectory Tracking

AbstractFlexible sensors are increasingly recognized for their transformative potential in wearable electronic devices, medical monitoring, and human‐computer interaction. Despite the advancements, developing a flexible sensor array with a simple structure and large area preparation for effective signal sensing and monitoring capabilities remains challenging. In this study, a hierarchical rGO‐based flexible triboelectric sensor (HG‐FTS) is scalably prepared by a simple blade‐coating approach, in which the nitrogen‐doped reduced graphene oxide (rGO) sheet is hierarchically deposited in a polydimethylsiloxane (PDMS) layer. The flexible triboelectric sensor performed in single electrode mode not only demonstrates exceptional reliability and consistency but also achieves a maximum voltage of ≈129 V and a power density of ≈0.5 W m−2. These characteristics enable the real‐time monitoring of human physiological signals and joint motion with high fidelity. Furthermore, an intelligent human‐computer interactive control system is developed using the HG‐FTS, featuring a digital array touch screen with a rectangular pattern. The build system can be successfully used for pressure sensing, object shape recognition, and trajectory tracking. This work provides a viable solution to the large area preparation and high‐performance flexible sensor manufacturing and demonstrates the potential application of HG‐FTS in human‐computer interaction, signal monitoring, and intelligent sensing.

AlGaN/AlN/GaN MOS-HEMTs with biomolecule cavities: a promising approach for SARS-CoV-2 biosensors

Abstract In this work, AlGaN/AlN/GaN MOS-HEMTs were investigated with a biomolecule cavity between two oxide layer under the gate region to determine their sensitivity and viability as biosensors. The area between the two oxide layers located below the gate electrode was used to detect the SARS-CoV-2 virus through DNA proteins. Threshold voltage and drain current analysis were carried out by modulating the dielectric of DNA filled in the cavity region to simulate the presence of the virus. The sensitivity of the device was analyzed using the ATLAS SILVACO simulation tool, focusing on various configurations. This included the impact of AlGaN composition (both thickness and Al mole fraction) and cavity configuration (length and thickness of the cavity). The simulation results revealed that device with barrier layer thickness of 15nm and Al mole fraction of 0.2 demonstrates maximum threshold voltage sensitivity SVth (%) of 86% and drain current sensitivity SIds(%)of 75%. Thedevice with cavity length 500 nm and cavity thickness 15 nm shows maximum sensitivity.This research suggests that the proposed structure has potential application in the detection of SARS-COV-2 virus.

Innovative bio-inspired solar cells using fly ash-based dye-sensitized cells with fruit extract enhancements and Averrhoa bilimbi electrolyte

This study responds to the urgent need for renewable energy in Indonesia, driven by climate change and the energy crisis, by developing dye-sensitized solar cells (DSSCs) using locally sourced, eco-friendly materials. Traditional silicon-based photovoltaic cells, which have plateaued at 27% efficiency, are costly and environmentally unfriendly, leading to the demand for alternatives like DSSCs, which offer lower production costs, flexibility, and effective performance in diffuse light. The research focuses on designing DSSCs with Fe and Mg extracted from fly ash as counter electrodes, dragon fruit peel as a natural dye sensitizer, and Averrhoa bilimbi as an electrolyte booster. UV-Vis spectroscopy demonstrated that dragon fruit dye absorbs light effectively in the 360-700 nm range, peaking at 550 nm, making it an ideal sensitizer for wide-band gap semiconductors. Voltage output tests showed that Fe-doped DSSCs consistently outperformed Mg-doped ones, with Fe-based cells generating a maximum voltage of 413 mV compared to 163 mV for Mg-based cells. Long-term testing over three months further demonstrated Fe-doped cells' superior performance, peaking at 454.6 mV, while Mg-doped cells reached 261.96 mV. These results highlight Fe's effectiveness as a doping material, improving DSSC efficiency and supporting the use of natural dyes and sustainable materials. The study aligns with prior research on the critical role of material properties and solar irradiance in DSSC performance, demonstrating the potential of using fly ash and natural dyes for efficient solar energy solutions in South Sumatra. Future research will focus on optimizing material composition for enhanced performance.

Variation in bioelectricity production in integrated CW-MFC: An insight into coliform inactivation affected by HRT and power density

In the current study, domestic wastewater was treated in three identical vertical up-flow reactors; R1 (constructed wetland), R2 (CW-MFC), and R3 (unplanted CW-MFC) under different HRTs of 36 h (Phase 1), 24 h (Phase 2), and 18h (Phase 3). Periodic reduction of HRT from Phase 1 to Phase 3 resulted in deteriorated organics and fecal coliform removal by the reactors. R2 showed higher pollutant removal and voltage generation in every phase of the study compared to R1 and R3. R2 exerted 93%, 87%, and 57% mean COD removal during Phase 1, Phase 2, and Phase 3; with maximum open circuit voltage generated as 925 mV, 695 mV, and 429 mV respectively. Linear regression analysis showed that operating voltage and power density had significant effects on the variance of effluent fecal coliform concentration. The regression analysis also revealed that 36 h – 24 h HRT was critical where power density influenced the pathogen inactivation considerably. Multiple batch studies revealed the main role of reactor media and plant roots was to support the attached microbial growth for biodegradation of the organics Radial oxygen loss did not affect the anaerobic environment at the anode after 800 days of reactor operation.

High‐efficiency multilevel inverter topology with minimal switching devices for enhanced power quality and reduced losses

AbstractThe advent of multilevel inverters (MLIs) has brought significant advancements in their applications across industrial, residential, and renewable energy sectors, as they produce high‐quality output voltage that closely approximates a sinusoid in small voltage steps or levels, resulting in lower total harmonic distortion (THD) and reduced electromagnetic interference (EMI). However, the MLI topologies require more switching unidirectional/bidirectional semiconductor devices with high standing voltage, gate drivers, and complex control strategies while attaining higher voltage levels. From this perspective of reducing component count and gate drivers, the objective is to develop a new MLI topology that overcomes the drawbacks above. In this article, a novel MLI topology is introduced in symmetric and asymmetric configurations aiming to attain fewer power electronic devices for synthesizing more steps in the load voltage in contrast with conventional topologies. The idea behind the approach is coining the series connected voltage source, which imbibes bidirectional current flow with an additional voltage source for performing algebraic operation under asymmetrical modes of operation. The proposed topology uses minimal on‐state switching devices leading to a diminution of power loss and voltage drop. The suggested topology is optimized for a fewer number of power devices, an input DC supply, and auxiliary gate drivers to achieve a maximum voltage level in the load terminals. The suggested topology has been verified in SIMULINK and the laboratory prototype is constructed in line with the simulated response to demonstrate its performance suitable for real‐time applications.

Enhanced chloramphenicol biodegradation and sustainable electricity generation via co-cultured electroactive biofilms modified with in-situ self-assembled gold nanoparticles and reduced graphene oxide.

Bioelectrochemical technology emerges as a promising approach for addressing the challenge of antibiotic residue contamination. This research innovated by incorporating in-situ self-assembled gold nanoparticles (Au-NPs) and reduced graphene oxide (rGO) into a co-cultured electroactive biofilm (EAB) of Raoultella sp. DB-1 and Shewanella oneidensis MR-1 (Au-rGO@R/S-C). Supported by the rGO scaffold, the embedding of Au-NPs at key intercellular sites, and the adhesion of extracellular polymeric substance (EPS), the Au-rGO@R/S-C EAB enhanced the bioelectrochemical performance of the inoculated microbial fuel cell (MFC), with a 34.4% increase in the maximum voltage output and a 1.95-fold rise in the maximum power density, enabling the complete degradation of 100mg/L chloramphenicol within 24h. Notably, the Au-rGO@R/S-C EAB adapted to increased chloramphenicol stress by amplifying EPS secretion, especially with an elevated protein/polysaccharide ratio. Further analysis indicated a positive correlation between excessive production of EPS, particularly the increase in tightly bound EPS, and the stability in balancing the self-protection and extracellular electron transfer efficiency of the Au-rGO@R/S-C EAB under environmental stress. Our findings present a crucial strategy for the rational engineering of EABs, leveraging their dual potential in both environmental remediation and clean energy production.

A diode-like integrated hydrogel for piezoionic generators and sensors

Wearable sensing electronic devices based on hydrogel are gradually developing towards multifunction and portability, however, efficiently harvesting energy from the surrounding environment to power traditional hydrogel-based wearable electronic devices is a major challenge. The assembly of multilayer heterogeneous hydrogels is a potential strategy to address this challenge. Herein, inspired by the structure of diodes, a diode-like integrated hydrogel composed of a three-tier structure of anionic polyelectrolyte hydrogel, polyacrylamide hydrogel and cationic polyelectrolyte hydrogel is developed. By the connection of polyacrylamide hydrogel, the composite hydrogel exhibits excellent structural stability and mechanical properties. Notably, due to the introduction of MXene ion-conducting microchannels, the directional transport of free cations and anions ionized by anionic and cationic polyelectrolytes is achieved, thereby improving the conductivity (74.58 mS/cm), sensing (gauge factor = 7.47) and piezoionic output performance of the composite hydrogel. The composite hydrogel-based sensor can sense tiny facial movements and recognize the direction of human movement, and the composite hydrogel-based piezoionic generator exhibit more efficient mechanical-electric conversion performance, which can output the maximum voltage of 1410mV, current of 28 μA, and power density of 2.9mW/m2 for a composite hydrogel of 5×5 cm2. The integration of multilayer heterogeneous hydrogels proposes a versatile strategy for the development of high-performance hydrogel-based self-powered sensing electronic devices, expanding the application of hydrogels in artificial intelligence and human-computer interaction.

A rotating piezoelectric energy harvester in a spindle shaft under magnetic repulsive-attractive forces

The utilisation of rotational motion in a piezoelectric energy harvester is believed to have significant potential for generating sufficient electrical energy to sustain self-powered wireless sensor systems. The system needs dynamic and rotating components, which means it must adapt to the environment and be integrated into the rotating shaft. Therefore, this study proposed a novel solution to effectively tackle these issues using the rotating piezoelectric energy harvester (RPEH). This was based on the magnetic repulsive and attractive forces produced by coupling stationary and rotating magnets on the piezoelectric surface. The magnets were arranged symmetrically on opposite sides to serve as the source of excitation. Moreover, the voltage and power generation capacity of the harvester were investigated when the system was subjected to different excitations of spindle shaft speed. The results showed that the system attained a maximum instantaneous output voltage of 8.1 V at a rotating speed of 1200 revolutions per minute (rpm), and this enabled the charging of a capacitor with a power level of 2.4 mW at a load of 10 kΩ. This showed that the proposed harvester had a significant level of durability and possessed considerable potential to supply power to wireless sensors.

A low-frequency vibration energy harvester based on a quasi-zero stiffness mechanism and magnetic repulsion

ABSTRACT This work proposes a piezoelectric energy harvester with magnetic repulsion and a quasi-zero stiffness mechanism to achieve self-powered functionality for microelectronic devices in low-frequency vibration environments (MR-QZS-PEH).The relationship between the stress and strain of the piezoelectric sheet is obtained according to the elastic theory of materials and the modal simulation of the piezoelectric sheet is conducted under different excitation frequencies. A series of experiments validate the impact of introducing nonlinear magnetic repulsive force into the quasi-zero stiffness mechanism on the efficiency of the device. The results show that the MR-QZS-PEH achieves the maximum voltage of 36.58 V when the mass block is 78.3 g and the spring wire diameter is 0.6 mm under 5.00 Hz excitation frequency and 40 mm displacement amplitude. The prototype achieves a maximum output power of 115 mW when the external resistance is 11kΩ. The MR-QZS-PEH can supply power 81 LEDs and the temperature and humidity sensor, demonstrating it can meet the power needs of microelectronic devices, which provides new ideas and methods for powering microelectronic devices in a vibration environment.

Impact of gate bias on TID responses of BCD MOSFETs

The total ionizing dose (TID) effect on MOSFETs, which use the Bipolar-CMOS-DMOS (BCD) technology, is investigated under different gate biases utilizing X-rays. The threshold voltage, maximum transconductance and subthreshold swing of the device before and after irradiation were obtained. The results indicate that the TID effect is significantly influenced by gate bias. For NMOSFET, the maximum threshold voltage shift occurs at a positive gate bias of 3 V. For PMOSFET, the minimum threshold voltage shift occurs at a negative gate bias of −3 V. The mechanism was revealed to be the result of the combined effects of initial recombination, hole capture, and electron tunneling processes. However, the case of PMOSFET differs from NMOSFET due to the disappearance of electron tunneling and the change in the direction of hole movement under negative gate bias.

Comparative performance analysis of mixed metal oxide sensors for dual-sensing leveraging machine learning

This paper presents the synthesis of mixed metal oxide (BaTiO3: ZnO) (B: Z) sensors with various molar ratios using a low-temperature hydrothermal method for dual sensing applications (gas and acceleration). The sensor developed with an equal molar ratio of 1B:1Z, showcases superior performance compared to unmixed and alternative mixed metal oxide sensors. This equilibrium in ratios optimally enhances synergistic effects between elements B and Z, resulting in improved sensing properties. Furthermore, it contributes to structural stability, enhancing performance in gas and acceleration sensing. A decreased band gap of 2.82 eV and a rapid turn-on voltage of 0.18 V were achieved. The acceleration performance of 1B:1Z sensor exhibits a maximum voltage of 2.62 V at a 10 Hz resonant frequency and an output voltage of 2.52 V at 1 g acceleration, achieving an improved sensitivity of 3.889 V g-1. In addition, the proposed gas shows a notable sensor response of ∼63.45% (CO) and 58.29% (CH4) at 10 ppm with a quick response time of 1.19 s (CO) and 8.69 s (CH4) and recovery time of 2.09 s (CO) and 8.69 s (CH4). Challenges in selectivity are addressed using machine learning, employing various classification algorithms. Linear discriminant analysis achieves superior accuracy in differentiating between CO and CH4,reaching 96.6% for CO and 74.6% for CH4at 10 ppm. Understanding these concentration-dependent trends can guide the optimal use of the sensors in different current applications.

High-Performance and Anti-Freezing Moisture-Electric Generator Combining Ion-Exchange Membrane and Ionic Hydrogel.

Moisture-electric generators (MEGs), which convert moisture chemical potential energy into electrical power, are attracting increasing attention as clean energy harvesting and conversion technologies. However, existing devices suffer from inadequate moisture trapping, intermittent electric output, suboptimal performance at low relative humidity (RH), and limited ion separation efficiency. This study designs an ionic hydrogel MEG capable of continuously generating energy with enhanced selective ion transport and sustained ion-to-electron current conversion at low RH by integrating an ion-exchange membrane (IEM-MEG). A single IEM-MEG exhibits a maximum open-circuit voltage (VOC) of 0.815 V and a short-circuit current (ISC) of 101 µA at 80% RH. Even at a low RH of 10%, a stable VOC of 0.43 V and ISC of 11 µA can be generated. Moreover, the antifreeze performance of the device is improved by adding LiCl, which significantly expands its operational range in low-temperature environments. Finally, a simple series-parallel connection of six IEM-MEGs can yield an enhanced VOC of 4.8 V and a ISC of ≈0.6 mA, and the scalable units can directly power commercial electronics. This study provides new insights into the design of MEGs that will advance the development of green energy conversion technologies in the future.

Study of the Influence of Electromagnetic Fields on the Corrosion of District Heating Pipelines

One of the primary indicators influencing the dependability of the district heating system system is the corrosion of the pipeline surface. This article presents the findings of measurements and tests conducted on the example of the heat supply system in our country. The effects of electromagnetic fields on the surface corrosion of heat pipelines located in the area intersecting with high voltage lines and along overhead power lines are discussed. In the contemporary era, ecological concerns, including those about electromagnetic ecology, have emerged as a significant area of focus within science, technology, and socioeconomics. The study of the impact of energy pollution factors has led to the development of electromagnetic safety norms and standards. However, there is a lack of unified norms and standards for electromagnetic ecological assessment at the current stage. The measurements indicate that the electric field strength is 0.38-32.33 V/m, while the magnetic field strength is 0.07-11.56 A/m. The voltage of the electric field is directly proportional to the voltage of the conductor. At the measurement point near the overhead power line (at a height of 1 m above the heat transmission line), the maximum voltage was 32.33 V/m. However, since the voltage of the magnetic field is directly proportional to the current running through the electric conductor, the current flowing through the conductor on the output of the extension generator had the highest value, resulting in the maximum magnetic field voltage of 11.56 A/m, which indicates that the measurement is accurate.

An Energy Modulation Interrogation Technique for Monitoring the Adhesive Joint Integrity Using the Full Spectral Response of Fiber Bragg Grating Sensors.

Adhesive joining has the severe limitation that damages/defects developed in the bondline are difficult to assess. Conventional non-destructive examination (NDE) techniques are adequate to reveal disbonding defects in fabrication and delamination near the end of service life but are not helpful in detecting and monitoring in-service degradation of the joint. Several techniques suitable for long-term joint integrity monitoring are proposed. Fiber Bragg grating (FBG) sensors embedded in the joint are one of the promising candidates. It has the advantages of being close to the damage and immune to environmental attack and electromagnetic interference. Damage and disbonding inside an adhesive joint will give rise to a non-uniform strain field that may bring about peak splitting and chirping of the FBG spectrum. It is shown that the evolution of the full spectral responses can closely reveal the development of damages inside the adhesive joints during tensile and fatigue failures. However, recording and comparing the successive full spectra in the course of damage is tedious and can be subjective. An energy modulation interrogation technique is proposed using a pair of tunable optical filters. Changes in the full FBG spectral responses are modulated by the filters and converted into a conveniently measurable voltage output by photodiodes. Monitoring damage development can then be easily automated, and the technique is well-suited for practical applications. Filter spectrum width of 5 nm and initial overlap with the FBG spectrum to give 40% of the maximum output voltage is found to be optimal for measurement. The technique is tested on embedded FBGs from different adhesive lap-joint specimens and successfully reflected the severity of changes in the full spectral shapes during the course of tensile failure. Moreover, the trends in these PD outputs corroborate with the V value previously proposed to describe the qualitative change in FBG spectral shape.

Triboelectric Nanogenerator Based on CPDs-WO3/MXene Bilayer Film for Triethylamine Sensing and Fish Meat Spoilage Detection.

With the increasing demand for food safety monitoring, the development of efficient, convenient, and green gas sensors has become a current research hotspot. Triboelectric nanogenerator (TENG) as a triethylamine sensor is a cutting-edge strategy for detection without the need for an additional power source. In this study, synthesized WO3/MXene materials were prepared and bilayer thin films of carbon quantum dots (CPDs)-WO3/MXene TENG. WO3 provides more active sites for improved material charge transfer efficiency. TENG achieved a maximum open-circuit voltage (Voc) of 30 V. The CPDs-WO3/MXene-3 TENG can also be used as a self-powered gas sensor (SPGS). As a charge-trapping layer, CPDs exhibit excellent charge trapping. The SPGS has a 53% response to 200 ppm TEA, and low detection at ppb level (139 ppb). The presence of WO3 improves the gas-sensing performance. Additionally, CPDs possess excellent conductivity and moisture resistance. Finally, it was studied to see how it reacts to TEA in fish meat under different conditions of spoilage. It provides approach to solving the transportation and preservation problems of fish meat.

A New Methodology for Selecting CT Scanning Parameters Depending on the Density of Materials.

The CT (computed tomography) scanner has been used for many years now not only for medical measurements but also in many industries, for example, in defectoscopy for measuring sheet thickness and checking the joining of materials, as well as for measuring the geometry of individual components. This type of scanner is a good complement to coordinate contact and non-contact measurements for intra-structural measurements and inaccessible places. The variety of materials, however, makes it very difficult to select individual CT parameters. In this paper, a curve for selecting the maximum and minimum voltage of the lamp depending on the density of a given material is determined and an interpolation polynomial (1d with a third-degree polynomial) is used, by defining third-degree glued functions (cubic spline) to determine intermediate voltage values to a given material density, so as to determine full data ranges. This approach can facilitate the work of selecting scanning parameters for non-destructive testing, as this is a difficult process and sometimes consumes half of the measurement time. The practical experiments were carried out at the Accredited Coordinate Metrology Laboratory to develop a multi-criteria matrix for selecting CT measurement parameters for measurement accuracy. This approach reduced the time by an average of half an hour and effectively optimized the selection of scanning parameters.

Hybrid Control Switching Technology for LLC Resonant Converter

Aiming at the problem of the circuit operating frequency changing beyond the regulation range and zero switching not being guaranteed when the input voltage range of the LLC resonant converter is large, a hybrid control technology with a variable structure and variable mode is proposed in this paper to realize the wide input range of the LLC resonant converter. Depending on the input voltage range, this technology can ensure the frequency range of the circuit and meet the realization conditions of zero voltage switching (ZVS) in different modes. The test results show that the circuit can control the frequency at 0 kHz~200 kHz, the phase shift range is 0~2π/5, the maximum voltage gain multiple is 3.3 times, and the control mode is three PWM hybrid switching control.

Analysis of Post-Treatment Heating of Stretchable Piezoelectric Electrospun Nanofibers

Electrospun piezoelectric nanofibrous membrane developed from Polyvinylidene fluoride (PVDF) embedded with thermoplastic polyurethane (TPU) composites found to have superior stretchability and piezoactivity. The piezoresponse behavior of different in-situ bended PVDF/TPU, up to 15wt.% of TPU, is examined using various blending ratios of PVDF and TPU. It has been shown that adding TPU with PVDF at certain specific concentration increased the nanofiber's piezo-efficiency.The generated nanomembranes are annealead at different temperatures up to 100°C. An extensive analysis of the effects of annealing is conducted on these nanomats, and it is thought to be a crucial post-treatment method for improving the piezoresponse of the manufactured nanomats. Nanofibers annealed at 100°C showed best effective response compared to all other samples and this revealed the effectiveness of annealing treatment in the enhancement of piezoactivity. The best effective composition of PVDF with 15 wt% TPU after an annealing treatment of 100°C generated a maximum voltage of 3.2 V under the effect of an applied force of 3 N, where unannealed sample of the same PVDF-TPU composition generated only a voltage of 2.2 V. This annealed piezo nanogenerator (PNG), can be considered an optimum option for electromechanical energy harvesting applications that require flexibility and self-power.