Load Resistance Research Articles

Prediction of the effect of load resistance and heat input on the performance of thermoelectric generator using numerical and artificial neural network models

The load resistance in the thermoelectric generators (TEGs) is crucial for optimizing power output, and managing load resistances and operating conditions are integral elements of TEG system design. In this context, it is very important to predict the performance of TEGs at variable operating conditions. This research addresses an important problem in TEG by predicting the effects of load resistance and heat input on performance using both numerical and ANN models. The three-dimensional finite volume methods applied by employing ANSYS software, and the results were compared with experimental and ANN results in terms of voltage, current, power output and efficiency. In case of ambient temperature values of 17 °C, the average absolute errors of ANN and numerical model were calculated as 2.09 % and 4.22 % for voltage output, 0.79 % and 7.73 % for current output, 5.35 % and 12.09 % for power output, 4.14 % and 12.09 % for efficiency, respectively. As a result, it was observed that the ANN model gives better results compared to the numerical model. The highest power output was obtained at load resistance of 5.4 Ω and hot surface temperature of 150 °C, with the value of 0.827 W experimentally, 0.905 W numerically, and 0.824 W with ANN models. Besides, to evaluate the effect of ambient temperature, two additional temperatures (10 °C and 25 °C) were tested and it was found that decreasing the ambient temperature increased the TEG performance. The results showed that significant improvements on power and efficiency performance of the TEG can be achieved with optimised operating conditions.

Effect of preparation design and endodontic access on fracture resistance of zirconia overlays in mandibular molars: An in vitro study.

To evaluate the fracture resistance of zirconia overlays, considering various preparation designs and the presence of endodontic access. Ninety translucent zirconia (5Y-PSZ) overlay restorations were divided into six groups (n = 15/group) based on different preparation designs, with and without endodontic access: chamfer margin 4mm above the gingival level without (group 1) and with endodontic access (group 2); margin 2mm above the gingival level without (group 3) and with endodontic access (group 4); overlay with no chamfer margin without (group 5) and with endodontic access (group 6). Restorations were bonded to mandibular first molar resin dies, and the groups with endodontic access were sealed with flowable resin composite. All restorations underwent 100,000 cycles of thermal cycling between 5°C and 55°C, followed by loading until fracture. Maximum load and fracture resistance were recorded. ANOVA with Tukey post-hoc tests were used for statistical comparison (α < 0.05). Fracture resistance significantly varied among overlay designs with and without endodontic access (p < 0.001), except for the no-margin overlays (groups 5 and 6). Overlays with a 2mm margin above the gingival margin with endodontic access (group 4) exhibited significantly higher fracture resistance compared to both the 4-mm supragingival (group 2) and no-margin (group 6) designs, even when compared to their respective intact groups (groups 1 and 5). There were no significant differences between the no-margin and 4-mm supragingival overlays. The more extensive zirconia overlay for mandibular molars is the first choice since the 2mm margin above the gingival level design withstood considerable loads even after undergoing endodontic access. A no-margin overlay is preferred over the 4-mm supragingival design as it preserves more tooth structure and there was no outcome difference, irrespective of endodontic access. Caution is warranted in interpreting these findings due to the in vitro nature of the study.

Operating characteristics study of a dual-opposed free-piston Stirling generator

Dual-opposed Free-piston Stirling generators (dual-opposed FPSGs) offer advantages of reduced vibration and increased power density, making them promising candidates for space and distributed energy applications. So far, operational characteristics of the dual-opposed FPSG have yet to be completely understood. This study focuses on a 3 kW dual-opposed FPSG prototype designed to integrate heat pipes. Through computational fluid dynamics and thermoacoustic analysis, a novel hot end heat exchanger with evenly-distributed heat pipe bore was discovered to deliver 12 kW heating power with a gas–solid temperature difference of 21 K. Subsequently effort combined thermoacoustically-based calculations with experiments to investigate the impact of two electrical connection methods of linear alternators on FPSG performance. Experimental results validated the numerical model, showing heat-to-electricity efficiency deviations within 5 % under different electrical connection modes. The FPSG consistently achieved its rated power in both series and parallel connection modes, exhibiting a thermal-to-electric efficiency of 25.2 %. Notably, the series connection mode demonstrates superior sensitivity and consistency compared to parallel connection. Further experiments revealed that charge pressure, load resistance and external capacitance all exerts limited impact on the consistency, while external capacitance significantly influenced acoustic impedance. This resulted in an enhancement in both hot-end wall temperature and heat-to-electricity efficiency, while minimizing power piston displacement and damping temperature when resonating with the inductance.

Rapid Prototyping and Hardware-In-the-Loop Verification of Enhanced Sliding Mode Control of an Asynchronous Machine Using a Xilinx System Generator and an FPGA-Zynq Board

This article describes rapid prototyping using the Xilinx system generator (XSG) of a direct field oriented control (DFOC) strategy based on improved super twisting sliding mode controllers (ISTSMCs) of an asynchronous machine to succeed a hardware implementation on a field programmable gate array (FPGA) board. The main goal is to enhance regulation loops governing rotor speed, rotor flux, and stator current components within the classical DFOC structure. These ISTSMCs replace integral proportional controllers, resulting in improved system dynamics, faster speed and torque responses, and heightened robustness against load and rotor resistance variations, surpassing other control methods. Additionally, the article aims to implement this DFOC-ISTSMC method on an FPGA board to reduce control system sampling time and loop delays, leveraging the FPGA’s parallel processing capabilities. The hardware architecture is designed using XSG in the MATLAB/Simulink environment, enabling effective simulation, testing, discrete algorithm creation, and VHDL code generation for FPGA implementation via the hardware-in-the-loop (HIL) process. Assessment involves digital simulation studies and HIL processes using XSG with a Xilinx FPGA Zynq 7000 under MATLAB/Simulink, demonstrating improved system performance, reduced time delays, and efficient FPGA utilization. This approach validates the effectiveness of the proposed DFOC-ISTSMC algorithm in enhancing control strategy for asynchronous machines.

Effect of water droplet wetting behavior on water-droplet-based electricity generator performance

Droplet-based electricity generators (DEGs) have garnered significant interest due to their straightforward metal substrate/dielectric/metal electrode configurations and their capacity to produce instantaneous high power. This study investigates the influence of droplet conductivity and drop conditions on circuit parameters through an analysis of I–V characteristics under varying load resistance conditions. The results reveal that alterations in droplet resistance and polytetrafluoroethylene (PTFE) charge density due to varying droplet dynamics play a pivotal role in shaping DEG output. The charged state of PTFE on DEG was found to differ with the expansion and contraction of the droplets.

Characterization of Treatment Resistance and Viral Kinetics in the Setting of Single-Active Versus Dual-Active Monoclonal Antibodies Against Severe Acute Respiratory Syndrome Coronavirus 2.

Monoclonal antibodies (mAbs) represent a crucial antiviral strategy for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, but it is unclear whether combination mAbs offer a benefit over single-active mAb treatment. Amubarvimab and romlusevimab significantly reduced the risk of hospitalizations or death in the ACTIV-2/A5401 trial. Certain SARS-CoV-2 variants are intrinsically resistant against romlusevimab, leading to only single-active mAb therapy with amubarvimab in these variants. We evaluated virologic outcomes in individuals treated with single- versus dual-active mAbs. Participants were nonhospitalized adults at higher risk of clinical progression randomized to amubarvimab plus romlusevimab or placebo. Quantitative SARS-CoV-2 RNA levels and targeted S-gene next-generation sequencing was performed on anterior nasal samples. We compared viral load kinetics and resistance emergence between individuals treated with effective single- versus dual-active mAbs depending on the infecting variant. Study participants receiving single- or dual-active mAbs had similar demographics, baseline nasal viral load, symptom score, and symptom duration. Compared with single-active mAb treatment, treatment with dual-active mAbs led to faster viral load decline at study days 3 (P < .001) and 7 (P < .01). Treatment-emergent resistance mutations were more likely to be detected after amubarvimab plus romlusevimab treatment than with placebo (2.6% vs 0%; P < .001) and were more frequently detected in the setting of single-active compared with dual-active mAb treatment (7.3% vs 1.1%; P < .01). Single-active and dual-active mAb treatment resulted in similar decrease in rates of hospitalizations or death. Compared with single-active mAb therapy, dual-active mAbs led to similar clinical outcomes but significantly faster viral load decline and a lower risk of emergent resistance.

Portable through-metal ultrasonic power transfer using a dry-coupled detachable transmitter

Ultrasonic waves can be used to transfer power and data efficiently through metallic enclosures when feedthroughs are not practical due to structural or electromagnetic shielding considerations. Previous implementations of ultrasonic power transfer (UPT) used a piezoelectric transducer permanently bonded to the metal for efficient ultrasonic coupling. For portable operation, it is essential to have a detachable transmitter (charger) that is only attached to the enclosure while transferring power. This requirement presents several design challenges; notably, detachable ultrasonic coupling typically relies on liquid or gel couplant, which may become inconvenient or less robust during repeated attachment and detachment. Thus, this work develops a dry-coupled detachable UPT system to transfer power efficiently through a metallic enclosure without the need for a liquid couplant. Low attenuation soft elastomers are experimentally tested with a magnetic setup to evaluate their dry-coupled efficiency. Samples with different materials and thicknesses are experimentally tested to select the best configuration for dry ultrasonic coupling. The softest elastomer tested yielded the best ultrasonic efficiency (AC-to-AC) of 68% at 1 MHz. A full DC-to-DC portable (battery-operated) UPT system was then developed and experimentally characterized. The system was capable of delivering up to 3 W of DC power to a resistive load with a total efficiency of 50%.

Development of 2400-2450 MHz Frequency Band RF Energy Harvesting System for Low-Power Device Operation.

Recently, there has been an increasing fascination for employing radio frequency (RF) energy harvesting techniques to energize various low-power devices by harnessing the ambient RF energy in the surroundings. This work outlines a novel advancement in RF energy harvesting (RFEH) technology, intending to power portable gadgets with minimal operating power demands. A high-gain receiver microstrip patch antenna was designed and tested to capture ambient RF residue, operating at 2450 MHz. Similarly, a two-stage Dickson voltage booster was developed and employed with the RFEH to transform the received RF signals into useful DC voltage signals. Additionally, an LC series circuit was utilized to ensure impedance matching between the antenna and rectifier, facilitating the extraction of maximum power from the developed prototype. The findings indicate that the developed rectifier attained a peak power conversion efficiency (PCE) of 64% when operating at an input power level of 0 dBm. During experimentation, the voltage booster demonstrated its capability to rectify a minimum input AC signal of only 50 mV, yielding a corresponding 180 mV output DC signal. Moreover, the maximum power of 4.60 µW was achieved when subjected to an input AC signal of 1500 mV with a load resistance of 470 kΩ. Finally, the devised RFEH was also tested in an open environment, receiving signals from Wi-Fi modems positioned at varying distances for evaluation.

Line and load regulation: a microcontroller-based experiment

Voltage regulators, the most common application of Zener diodes, are included in many electronic devices we use in our daily lives. Therefore, students need to learn about regulators to understand the place of Zener diodes in modern electronic technologies. This study focuses on a microcontroller-based experiment that can be used to teach line and load regulation with real-time graphics. The main advantage of the designed experiment over its classical equivalent is its ability to display autonomous and real-time data display. It also eliminates the problem of determining the load resistance, which is the main difficulty of the classical experiment.

Development of flexible high-performance PDMS-based triboelectric nanogenerator using nanogratings

This article investigates the performance of a contact-mode Triboelectric Nanogenerator (TENG) utilizing polydimethylsiloxane (PDMS) with nano gratings as a dielectric in a metal-dielectric configuration. The evaluation encompasses the impact of gratings, tapping frequency, various load conditions, and contact area on the TENG performance. The fabrication involves spin-coating PDMS onto a master mold to create the device. Experimental measurements reveal a significant enhancement of 97% in open-circuit voltage by introducing gratings on PDMS. Furthermore, as the tapping frequency increases from 1 Hz to 3 Hz, there is a corresponding rise of 108% in output voltage. The influence of load resistance on TENG output performance demonstrates its ability to drive different loads efficiently. Moreover, enlarging the contact area of the device substantially increases the open-circuit voltage. A device with a 400 mm2 contact area can generate a voltage of 80 V at a low frequency of 3 Hz, indicating the importance of considering device size and contact area for specific applications. A practical circuit integrating a TENG with a full-wave bridge rectifier demonstrates energy harvesting capabilities by successfully illuminating a light-emitting diode (LED) and charging various capacitors. The fabricated devices exhibit better performance along with a cost-effective and easy fabrication process.

Numerical investigation of smart material-based structures for vibration energy-harvesting applications

Abstract The present work deals with energy-harvesting devices, which are useful in scavenging power using piezoelectric materials. Utilizing classical beam theory and classical plate theory, finite element modelling has been carried out to optimize the performance of output power of a cantilever beam and a flexible rectangular plate. Harmonic oscillations and base excitation will be the two different forcing functions used to drive the system. Based on this, numerical investigations of the performance of output power for the piezoelectric cantilever beam and flexible rectangular plate with different cases are considered. The present work is also useful for designing the piezoelectric cantilever beams and plates to extract maximum output power within the frequency ranges from 0 to 200 Hz. Numerical investigations on the piezoelectric cantilever beam and flexible rectangular plate with different cases reveal that the performance of output power is influenced by factors like load resistance, applications of with and without host structures, and different design parameters like unimorph, bimorph, embedded, line- and cross-type piezoelectric patch arrangements.

Design, modeling and experiments of bistable piezoelectric energy harvester with self-decreasing potential energy barrier effect

It is difficult for conventional bistable energy harvesters to undergo interwell motion in weak excitation environment. In this study, a bistable energy harvester with self-decreasing potential energy barrier effect is proposed, which innovatively turns a fixed end of S-shaped generator beam into the movable end with a spring oscillator, which effectively decreases the potential energy barrier and makes the harvester susceptible to interwell motion. Furthermore, a theoretical analysis of the nonlinear driving magnetic force and the system governing equations is carried out, then a numerical simulation of potential energy surface of harvester is performed to demonstrate the effect of the self-decreasing potential energy barrier in detail. The effect of spring pre-compression and stiffness of the moveable end on the system potential energy is analyzed by numerical simulation. Finally, the key parameters affecting the output performance, such as spring pre-compression, magnets distance, and external load resistance, are analyzed. The harvester has a maximum effective bandwidth of 6.62Hz (4.61–11.23Hz), a maximum peak-to-peak voltage of 10.2V, an RMS voltage of 1.3V, and a maximum output power of 2.91 μW. The proposed harvester achieves efficient broadband energy harvesting in low frequency environments.

Spring-like behavior of cementitious composite enabled by auxetic hyperelastic frame

A novel highly compressible auxetic cementitious composite (ACC) is developed in this work. Contrary to conventional cementitious materials, such as plain concrete and fiber reinforced concrete, the ACC shows strain-hardening behavior under uniaxial compression: the stress continuously increases with strain up to approximately 40 % strain. On one hand, in the early compression stage, the ACC exhibit highly recoverable deformability of 10 % strain under cyclic loading (20 times higher than the constituent cementitious material). In addition, the ACC shows fatigue damage until the stiffness/strength and energy dissipation plateau values are reached after 500 cycles. At 2.5 % strain amplitude, the plateau stiffness/strength is approximately 120 MPa/3 MPa, while these values are only 25 MPa/1.2 MPa at 5 % strain amplitude. In contrast, the energy dissipation plateau of the ACC is independent from the amplitude and remains at 0.05 J/cm3. On the other hand, due to the strain-hardening behavior, the ACC exhibits significantly improved energy dissipation capacity compared to both the conventional cementitious materials and the auxetic frame. This behavior is achieved by a tailored composite action: integrating cementitious mortar with 3D printed thermoplastic polyurethane (TPU) auxetic frame. A rotating-square auxetic mechanism was designed for the TPU frame for the ACC to achieve the tailored cracking behavior. The horizontal ACC cells enable large deformability by enlarging the crack width under the confinement of the auxetic frame, while the vertical cells work as stiffening phase to ensure load resistance. Owing to the outstanding mechanical properties, the ACC shows great potential to be applied in engineering practice where high compressive deformability is required, for instance yielding elements for squeezing tunnel linings.

Achieving solar-thermal driven dual functional device utilizing flexible PDA coated sponge integrated thermoelectric module design for water purification and power generation

The design of an efficient solar energy collector for solar-thermal-driven water purification and power generation is a promising strategy to concurrently mitigate the shortage of fresh water and energy crises. However, harvesting low-grade thermal energy in an eco-friendly and cost-effective manner through solar-thermal materials for water evaporation and electric cogeneration remains challenging. Herein, we demonstrate a dual-functional device integrating solar-thermally driven water purification and thermo-induced power generation. This typical design, fabricated via polydopamine (PDA) tightly deposited onto melamine sponges (PDA@Sponge) via H-bonds, along with a thermoelectric generator (PDA@Sponge/TEG), showcases superior solar-thermal-driven dual-functional application. The critically structurally adjustable PDA@Sponge possesses excellent homogeneity and stability, weakening interfacial hydrogen bonding between water molecules, favoring the evaporation and overflow of water molecules. The optimal serrated design achieves a water evaporation rate of up to ∼1.50 kg −2h−1, with an efficiency of ∼ 94.04 % under one sun, surpassing the most of previous reports, owing to its special tip thermal localization effect and rational water transportation management. Simultaneously, the designed PDA@Sponge/TEG yields an open-circuit voltage and short circuit current of 55 mV and 22 mA, respectively, along with a maximal output power of 162 μW (40.5 μW/cm2) at a load resistance of 7.5 Ω, under one sun and room temperature. Notably, such a device, after multiple series connections, can charge a capacitor to 1.5 V within 1 min, capable of powering low-energy electronic devices such as smartwatches and LED lights. By efficiently integrating of multiple solar-thermal-driven processes, our research promotes the design of multifunctional devices to promise an approach for desalinating seawater, purifying wastewater, and powering low-energy electronics, especially in remote areas lacking power stations and/or water treatment facilities.

Enhancing the piezoelectric coefficient of SrTiO3 nanocubes and PVDF film deposited by supersonic spraying for energy-harvesting nanogenerators

Many perovskites and their piezoelectric composites have been investigated for harvesting ambient mechanical energy over the past two decades; however, the prospects for their commercialization appear remote because of several practical challenges. Therefore, highly scalable supersonic cold-spraying technology was used to fabricate flexible piezoelectric films of poly(vinylidene fluoride) (PVDF) and a novel perovskite SrTiO3 (ST). Substantial shear stress was exerted on PVDF during cold spraying owing to the hydrothermally synthesized SrTiO3 nanocubes and supersonic velocity, and the resulting film delivered an effective piezoelectric coefficient (69.6 pm·V−1) as confirmed by piezo-response force microscopy. As a result, the piezoelectric nanogenerator yields a maximum power of 130 µW at a load resistance of 0.9 MΩ. The composite film exhibited durability for 21,000 tapping cycles with 20 N applied force and 7 Hz frequency. The flexibility endurance was confirmed from 3000 bending cycles. PENG attached to knee delivered 1 and 2.3 V on bending to 45 and 90°, respectively. After electrical poling, the PENG was subjected to a 20 N tapping force that yielded a piezopotential of 31 V. To the best of our knowledge, this is the first time piezoelectricity was obtained using an ST/PVDF composite via mechanical energy harvesting. The flexible PENG film deposited by cold-spraying shows good potential for wearable self-powered devices.

Physical, rheological and micro characteristics of ARA/Nano-TiO2 composite modified asphalt before and after short-term aging

This paper aims to investigate the composite application of nanomaterials and natural asphalt in order to enhance the road performance of asphalt pavement. The objective is to develop high-performance modified asphalt that improves the durability, reliability, and load resistance of asphalt roads while reducing resource waste and environmental pollution. The composite modified asphalt was prepared by adding different blends of Albanian natural rock asphalt (ARA) and 1% of nano titanium dioxide (Nano-TiO2), and the basic properties and rheological properties of the asphalt before and after aging were tested by using basic performance tests and temperature scanning tests. Subsequently, the microscopic morphological characteristics of the asphalt were observed by scanning electron microscope and atomic force microscope, and the number of bee structures, the area share of bee structures, root mean square roughness Rq, and arithmetic mean roughness Ra were used as microscopic quantitative indexes. The results indicate that the complex modulus and rutting coefficient of ARA/Nano-TiO2 composite-modified asphalt increase with an increase in ARA dosage when the dosage of Nano-TiO2 is 1%. The asphalt modified with Nano-TiO2 composite blended with 15% ARA exhibits higher residual needle penetration, composite modulus ratio, rutting coefficient ratio and lower softening point increment compared to 70# asphalt. The bitumen modified with titanium dioxide nanocomposite blended with 15% ARA exhibits higher Rq and Ra and a more stable phase structure before and after aging. 15% of ARA/Nano-TiO2 composite-modified asphalt has higher Rq and Ra before and after aging, and its phase structure is more stable. The results show that ARA/Nano-TiO2 composite-modified asphalt has better high-temperature deformation resistance and aging resistance than 70# and that 15% ARA is recommended as the optimum amount of composite-modified asphalt.

Design and optimization of a miniaturized dual band rectenna for wireless power transfer applications

This paper presents the design of a compact printed rectenna circuit suitable for wireless power transfer applications at frequencies 900 MHz and 1450 MHz. The rectenna circuit consists of a rectangular patch antenna measuring 17.7 x 8.85 mm2, printed on a Rogers RO4003 substrate. It also includes a voltage doubler (VD) circuit comprising Schottky diodes (SMS7631) and an impedance-matching circuit. The design and optimization of the antenna are performed using Ansys HFSS software, while the DC and RF features of the VD circuit are analyzed using the Advanced Design System (ADS) software. The circuit design is presented in two stages: one for single-frequency operation at 900 MHz and another for dual-band operation at 900 and 1450 MHz. The design of single-stage and double-stage VD for dual-band operation is also discussed in this paper. The rectenna's Power Conversion Efficiency (PCE) is evaluated under various load and input power conditions. The maximum DC output voltage measured is 5.318 V at 900 MHz and 5.52 V at 1450 MHz. Furthermore, the maximum PCE achieved is 53% and 54% for 900 MHz and 1450 MHz respectively. These values are obtained with a RF input power level of 20 dBm and a load resistance of 10 KΩ.

Implementation of modified P&O and an adaptive fuzzy logic controller based MPPT tracking system under partial shading and variable environmental conditions

Most of the conventional Maximum Power Point Tracking (MPPT) Algorithms provide the finest efficiency during uniform irradiation conditions, but under variable irradiation or partial shading condition (PSC), the performance deteriorates and the solar PV system is unable to provide the maximum electricity out of the PV Modules. This degradation in performance occurs due to the presence of numerous local maximum power points (LMPP) and a single global maximum power point (GMPP) in the power versus voltage (P-V) characteristics and the perfect tracking of these LMPP is not possible with the prevailing MPPT algorithms. In order to eradicate this shortcoming, we have proposed the implementation of an adaptive Fuzzy Logic Controller (FLC) based on Perturb and Observe (P&O) technique by employing a boost converter with variable resistive load under uniform irradiance condition (UIC), dynamic atmospheric conditions (DAC) and PSC in this article. We also demonstrated the usage of a simple and improved P&O algorithm by employing a buck boost converter for faster tracking time. These two suggested approaches of FLC and P&O incorporate a variable load scenario and a stable load scenario respectively to address the problem of output voltage oscillation in a PV-based system. The FLC is designed to adjust the dynamic change in step size based on the rate of change of the yield power of the PV panel to reduce oscillations in output of the boost converter and the PV system. According to the results of this analysis, the recommended FLC-based P&O (FLC-P&O) algorithm outperforms the proposed P&O algorithm under DAC and PSC with respect to tracking speed, steady-state error, and dynamic response. Apparently, it can be concluded that the proposed FLC-P&O technique can be applicable to real-time systems for reliable and efficient operation of the boost converter and add to the stability and simplicity of the contemporary PV-based systems.

Performance study of an array piezoelectric energy harvester for pressure pulsation vibration energy in water hydraulic system

In this paper, an array piezoelectric energy harvester (APEH) is designed for energy collection from water hydraulic system. The APEH is arranged in a spatial axial array, exhibiting excellent insulation and waterproof properties. The effects of connection modes and pressure pulsation parameters on the output performance of APEH are investigated through theoretical analysis, simulation and experiment. The results show that the output electric energy of each piezoelectric disk is consistent, and it is generated by the deformation caused by pressure pulsation. The connection modes show significant differences at different resistances. Series and parallel connections have the same maximum output power. The parallel connection has a smaller optimal resistance and has advantages in practical engineering applications. Both the pressure amplitude and the pulsation frequency affect the output voltage and power and increasing the pulsation frequency leads to the decrease of optimal resistance. By employing parallel connection, APEH can achieve higher output at lower load resistances. When the resistance is 12 kΩ, the average power and power density are reach as 997.63 μW and 2.54 μW mm−3, respectively. In summary, the APEH proposed in this paper offering a viable solution for energy recovery in water hydraulic systems and the sustainable power supply of the sensors, along with providing relevant theoretical references and practical schemes.

The Advancement and Utilization of Marx Electric Field Generator for Protein Extraction and Inducing Structural Alterations

This study introduces an innovative two-range, 12-stage Marx pulse generator employing thyristor switches designed specifically for the electroporation of biological cells. The generator consists of two module capacitors of different capacitances (1 μF and 0.25 μF), which enable the generation of electrical pulses with different durations and amplitudes of up to 25 kV. Safety aspects, including overcurrent and overvoltage protection mechanisms, are implemented in both the software and the hardware. In the experimental section, the tests of the Marx generator with resistive load are described in detail, and the results for the voltage fluctuations, pulse duration, and output characteristics of the generator are presented. The advantages of the design, including the high output voltage, the wide range of repetition rates, and the flexibility of the pulse parameters, are emphasized. Additionally, the research showcases the utilization of the devised generator for industrial purposes. Hence, an investigation into the efficiency of protein extraction from microalgae (Chlorella vulgaris) and the impacts of pulsed electric fields (PEFs) on the structural characteristics of casein micelles (CSMs) was chosen as an illustrative example. The obtained results provide valuable insights into the application of PEF in food processing and biotechnology and underline the potential of the developed generator for sustainable and environmentally friendly practices.