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AbstractThis study expands the investigation of a mathematical method for predicting the airflow rate during the vacuum dewatering process of papermaking based on our previous research. By integrating poroelastic theory and initial saturation thickness, based on experimental data with a range of 20–60 kPa pressure difference and 20-200 g·m−2 basis weight, a mathematical method with a semi-theoretical model for compression characteristics of the wet fiber web, the poroelastic porosity model (PEPM), was developed to support and expand on our previously established empirical model for porosity variations in wet fiber web, the variable porosity model (VPM). The accuracy of the mathematical method with the PEPM in predicting the airflow mass flux passing through the wet fiber web was validated using experimental data with a range of 0–60 kPa pressure difference and 20-200 g·m−2 basis weight. The mean relative errors with the PEPM within the pressure difference range of 0-20 kPa and 0-60 kPa were 7.68% and 8.80%, respectively, compared to 17.44% and 11.67% for those with the VPM, demonstrating the improved applicability and generalization of the mathematical method, particularly in the zone of low pressure difference exceeding the range of the modeling experimental data. The PEPM effectively revealed the strain hardening behavior during the compression process and the diminishing returns of energy in the vacuum dewatering process with an increasing pressure difference. The developed mathematical method with the PEPM for the compression characteristics of the wet fiber web provides an effective and accurate way to predict the airflow rate during the vacuum dewatering process of papermaking. [ABSTRACT FROM AUTHOR]

In modern days, MLIs comprise a lot of concentrations in academia and industry. As they are altering interest in a feasible technology in supporting frequent applications of renewable energy conversion systems and drives, these huge power and medium/higher voltage applications and MLIs are extensively used as one of the sophisticated powers converter topography. The MLIs are divided into two types such as asymmetric and symmetric. MLIs of the asymmetric kind have more amount of output AC voltage stage with fewer DC input source voltage and switching components. In this research paper, asymmetric single-phase cascade full-bridge MLI is developed with carrier-based unipolar PWM techniques. This MLI can generate nine-stage of output AC voltage through eight switches and two input DC sources. It is tested through a variety of multicarrier unipolar PWM control combinations. The Phase Disposition (PD), Alternating Phase Opposition Disposition (APOD), Carrier Overlapping (COP) and Variable Frequency (VF) are all PWM control which included in support of preference of single-phase nine-stage ternary cascade multilevel inverters. With various modulation indices (ma), the harmonic substance of output AC voltage for each approach is observed and tabulated. The proposed design for generating nine-stage output AC voltage is demonstrated using MATLAB-SIMULINK and confirmed using a laboratory-based prototype model. The results show that the unipolar Alternating Phase Opposition Disposition PWM technique that provides a high-quality output voltage with less harmonic distortion. Besides, the performance of Carrier Overlapping PWM techniques is greater since it produces a superior fundamental RMS output AC voltage. [ABSTRACT FROM AUTHOR]

Triboelectricity has emerged as a promising and novel method for low-power systems. In this study, a novel system is presented that converts wind energy into electrical energy through triboelectric energy conversion. The proposed system is based on the principle of a Van de Graaff machine. As is known, the required mechanical energy in a Van de Graaff generator is supplied by a DC motor. In this study, the required mechanical energy is provided by the wind using a propeller system, where the mechanical energy from the wind rotates a belt system, storing static charges generated by the friction of different materials and converting them into electrical energy. A laboratory-scale generator was manufactured, and data were collected under various experimental conditions. It was observed that the experimental generator could charge a 100 µF capacitor to 20.7 V within 6 min at a wind speed of 7 m/s. Furthermore, it was observed that the presented generator exhibited an energy generation capacity of 21.4 mJ over the same duration. Although the obtained energy is low, the simplicity of the system, absence of a traditional electric generator, and the potential to provide necessary energy production for off-grid, remote, low-power applications with improvements are considered its main advantages. [ABSTRACT FROM AUTHOR]

The homogeneous and heterogeneous reactions can provide important insights into the design and optimization of nanofluid-based heat transfer systems for various applications, such as in thermal management, energy conversion, and cooling. Understanding such pivotal role of homogeneous and heterogeneous reactions in the nanofluid flow modeling, this study aims to explore the consequences on the nanofluid flow comprising graphene oxide/water mixture through a permeable channel impacted by incorporating uniform homogeneous–heterogeneous reactions and heat generation/absorption respectively. The novelty of the presented model is translated by incorporating the thermal conductivity model that integrates the volume fraction of particle, diameter, and nanolayer impacts. The nanofluids possess multi-directional applications including nano drug delivery, cooling of computer microchips, optical devices, etc. The fluid system is formulated using Tiwari and Das nanofluid flow model. The ordinary differential equations (ODEs) are acquired by adopting apposite transformations and numerically computed utilizing the bvp4c method. Moreover, the impacts of the resulting physical parameters on the distributions of temperature, velocity, and nanoparticle volume fraction are examined using graphical representations. It is comprehended that nanofluid velocity declined for the porosity and magnetic parameters. Nevertheless, an upsurge in the fluid temperature is witnessed for the heat generation/absorption parameter. In addition, the heat transfer rate is more prominent in the case of a strong magnetic field. The validity of the envisioned model is also a highlight of this investigation. [ABSTRACT FROM AUTHOR]

Heterogeneous photocatalysis, as an energy-saving technology, is a fascinating strategy to tackle environmental issues and energy shortages. The efficacy of these processes is severely relevant to the suppression of charges recombination, which hinders the widespread utilization of these processes. The segregation of charges from fast recombination can be considerably improved by the formation of heterojunction among the components of photocatalysts. Nevertheless, the formed heterojunction between different semiconductors diminishes the continuity of the charges carriers transfer amongst the semiconductors. Moreover, the construction of heterojunctions significantly relies on matching of band structures of the desired semiconductors. Hopefully, homojunction construction between different exposing facets, morphologies, and crystal phases of a single semiconductor is a feasible strategy for impressively suppression of charges from recombination. In comparison with the heterojunction photocatalysts, the almost identical components in both sides of the junction area provide not only the incredibly matched lattice, but also the integrity of bonding between the counterparts, which facilitates the charge migration within the photocatalyst. Furthermore, the established built-in electric field in the junction regions could enforce the charge carriers for efficiently separation and transfer within these photocatalysts. Herein, we reviewed the latest researches about the emerging homojunction photocatalysts and their application in the degradation of various wastewater pollutants. The present review intends to stimulate the research communities to focus on this kind of photocatalysts, as emerging materials, with the impressive performances in the photocatalytic processes. [ABSTRACT FROM AUTHOR]

Artificial enzymes based on inorganic solids with both enzyme-mimetic activities and the special material features has been a promising candidate to overcome many deleterious effects of native enzymes in analytical applications. Polyoxometalates (POMs) are an importance class of molecular metal-oxygen anionic clusters. Their outstanding physicochemical properties, versatility and potential applications in energy conversion, magnetism, catalysis, molecular electronics and biomedicine have long been studied. However, the analytical applications of them is limited. Recently, the intrinsic enzymatic activities of POMs have also been found and become an area of growing interest. In this review, along with other reports, we aimed to classify the enzymatic activity of POMs, summarize the construction of POMs-based enzymes, and survey their recent advances in analytical fields. Finally, the current challenges and trends of the polyoxometalates with enzymatic activity in future chemo-/bio-sensing applications are briefly discussed. [ABSTRACT FROM AUTHOR]

Nowadays, the demand for electronics has increased, which requires some amount of input supply. This energy supply is now shifted from conventional to new techniques such as solar energy, wind energy and many other so-called free energies. Another type of free energy in an environment is sound energy; sometimes, it is referred to as noise. Hence, this article aims to convert this noise into electrical output to utilise it and drive small electronic applications. Nevertheless, the noise is uncomfortable for humans; hence, this experiment does not only convert energy but also reduces the noise amplitude. Here, the polyvinylidene difluoride (PVDF) piezoelectric element converts mechanical vibrations into electricity. It is employed in a foam block, and the sound source is placed at different heights of the foam block, just to analyse the output signal after sound impingement from different angles. Here, the maximum output peak of 80 mV is seen at 650 Hz and 82.9 dB. Likewise, different peaks of outputs have been observed. Also, noise reduction has been observed in this experiment; the maximum reduction of noise amplitude has occurred in the frequency range of 1100 Hz to 1200 Hz. [ABSTRACT FROM AUTHOR]

In the modern era, inorganic nanoparticles have received profound attention as they possess boundless applications in various fields. Among these, vanadium-based nanoparticles (VNPs) are highly remarkable due to their inherent physiological and biological properties with many therapeutic and other applications, such as drug delivery systems for diseases like cancer, environmental remediation, energy storage, energy conversion, and photocatalysis. Moreover, physically, and chemically synthesized VNPs are very versatile, however, these synthesis routes cause concern to health and the environment due to the highly savage reaction conditions, using highly toxic and harsh chemicals, which compel the researchers to develop an eco-friendly, greener, and sustainable route for synthesis. In this outlook, to avoid the innumerable limitations, a bio approach is used over chemical and physical methods. This present review emphasis on the role of various biological components in the synthesis, especially Phyto-molecules that acts as capping and reducing agent, and solvent system for the nanoparticles synthesis. Furthermore, the influence of various factors on the biogenic synthesized nanoparticles has also been discussed. Finally, potential applications of as-synthesized VNPs, principally as an antimicrobial agent and their role as a nanomedicine, energy applications as a supercapacitor, and photocatalytic agents, have been discussed. [ABSTRACT FROM AUTHOR]

The direct drive Permanent Magnet Linear Generator (PMLG)-based Ocean Wave Energy Converters (OWECs) produce variable A.C. voltage. In this article, the variable A.C. voltage is converted into a variable D.C. voltage by a standard rectifier. After that, a buck–boost inverter is used to produce constant amplitude A.C. voltage at the load end. The buck–boost inverter, implemented here, operates in three modes: buck, boost, and buck–boost. Furthermore, a switching algorithm is developed to generate reference A.C. voltage. Systematic design of power converter, small-signal analysis, and PWM control strategy are discussed. The simulation results and results from a laboratory prototype are presented to support the theoretical concepts. [ABSTRACT FROM AUTHOR]

The turbine is a crucial component in harnessing ocean thermal energy (OTE), and the impact of the nozzle on turbine performance is significant. TC-profile nozzles have been proven to operate efficiently in air turbines under high-temperature and high-pressure conditions. However, their performance in ocean thermal energy conversion (OTEC) turbines using organic working fluids (low-temperature and low-pressure) still requires further research. Therefore, we focused on a practical 100 kW OTEC turbine equipped with different types of TC-profile nozzles. Three-dimensional numerical models were established, and the simulation results demonstrated that the turbine efficiency using TC-3A was generally higher than other turbines, reaching an optimal efficiency of 89.4%. The turbine can operate efficiently at deviations from the design point of + 10.27% or −31.39% in mass flow rate, ±3°C in inlet temperature, and + 20% or −11.43% in rotor speed during off-design conditions. The results revealed the adaptability of TC-3A nozzles to the OTEC environment and their excellent off-design performance. The study could provide valuable guidance and references for the application of TC-type nozzles in the field of OTEC turbines. [ABSTRACT FROM AUTHOR]

Bismuth oxyhalides (BiOX) nano-materials are considered to be the most encouraging candidates to deal with environmental remediation, energy conversion, and degradation of organic pollutants because of their attractive characteristics, such as appropriate band structure, suppressed charges recombination ability, and good catalytic activity. The pure BiOX does not justify the advisable fine-tune photocatalytic efficiency. Therefore, several BiOX morphologies are synthesized, such as atomic layers, ultrathin nano-sheets, nano-spheres, and nano-tubes to enhance multiple applications performance. Moreover, the photocatalytic sites, quantum efficiency, charge separation, and light absorption efficiency of BiOX are largely studied for higher photocatalytic activity. Generally, we reviewed the highly advanced strategies for enhanced photocatalytic activities including simultaneous decontamination of wastewater as well as energy conversion. Furthermore, the review objective; is to summarize recent scientific and technological challenging about bismuth oxyhalides composites including fabrication methods, photocatalytic activity, and performance improving challenging of BiOX based photocatalysts. Moreover, we proposed comprehensive upcoming positive advances and developments comprising potential applications on behalf of BiOX based photocatalysts. [ABSTRACT FROM AUTHOR]

Sludge accounts for the highest percentage of waste emissions and needs to be treated efficiently for environmental issues, such as water problems, sanitation and CO2 emission. Although various processes for sludge treatment, such as dewatering, fermentation, drying, carbonization, composting etc., have been developed, effective sludge drying technique was investigated in this study, which can apply not only to organic, but also to inorganic sludge. Besides, the efficient sludge drying process has a potential to exceed the energy conversion efficiency of methane fermentation process by improving the drying efficiency. However, drying technique implemented in this study does not improve the efficiency of sludge drying equipment as in the traditional way, but accelerates sludge drying rate by changing the sludge properties itself to those suitable for drying by adding drying accelerator. In this experiment, resin emulsions were used as a drying accelerator, and sludge drying experiments were conducted using 30 different resin emulsions. The drying acceleration mechanism of resin addition sludge was also inferred by evaluating the change of the resin-addition sludge property. The results revealed that the physical properties of the resin have little influence on the drying acceleration, but the development of hydrophobicity associated with resin curing may have a significant effect on sludge drying acceleration. [ABSTRACT FROM AUTHOR]

As an important part of water splitting, the oxygen evolution reaction (OER) requires efficient, low-cost, and stable catalysts to overcome its sluggish kinetic barrier. In this study, based on previously reported OER catalyst materials of boron monosulfide mixed with graphene (r-BS+G), nickel foam (NF) is introduced as a supporting material for an r-BS+G electrocatalyst. The resulting r-BS+G-NF exhibits a very low overpotential at 10 (245 mV), 100 (308 mV), and 500 (405 mV) mA cm−2, with a low Tafel slope (56 mV dec−1). In addition, r-BS+G-NF exhibits high durability and can maintain high activity for more than 100 h at 100 mA cm−2. This is in sharp contrast to the catalyst without graphene (r-BS+NF), which shows lower durability. The results suggest that the unique morphology of the NF provides a large electrochemically active area and exposes more active sites on the surface of the prepared electrocatalyst, while the flexible graphene sheets play an important role as a support for effectively combining r-BS and NF. Consequently, the self-supporting structure can improve the OER performance as well as stability. Therefore, this study provides a promising strategy for use as an efficient and stable OER catalyst at high current densities. In the realm of electrocatalysis and the quest for sustainable energy conversion and storage technologies, our research introduces a distinctive contribution in the form of a nickel-foam-based boron monosulfide – graphene electrocatalyst (r-BS+G-NF) for the Oxygen Evolution Reaction (OER). Thanks to the porous structure of nickel foam and the important role of graphene in combining r-BS and nickel foam, r-BS+G-NF exhibits high catalytic activity and long durability for up to 100 hours. The findings presented in this paper represent a significant advancement in the field of electrocatalysis, with the potential to impact the development of cleaner and more efficient energy conversion and storage technologies. [ABSTRACT FROM AUTHOR]

Graphdiyne (GDY) is an emerging two-dimensional carbon allotrope featuring a direct bandgap and fascinating physical and chemical properties, and it has demonstrated its promising potential in applications of catalysis, energy conversion and storage, electrical/optoelectronic devices, etc. In particular, the recent breakthrough in the synthesis of large-area, high-quality and ultrathin GDY films provides a feasible approach to developing high-performance electrical devices based on GDY. Recently, various GDY-based electrical and optoelectronic devices including multibit optoelectronic memories, ultrafast nonvolatile memories, artificial synapses and memristors have been proposed, in which GDY plays a crucial role. It is essential to summarize the recent breakthrough of GDY in device applications as a guidance, especially considering that the existing GDY-related reviews mainly focus on the applications in catalysis and energy-related fields. Herein, we review GDY-based novel memory and neuromorphic devices and their applications in neuromorphic computing and artificial visual systems. This review will provide an insight into the design and preparation of GDY-based devices and broaden the application fields of GDY. [ABSTRACT FROM AUTHOR]

The miniaturisation of systems has widely attracted researchers to contribute to the thermal performance enhancement utilising efficient heat transfer devices. Pulsating heat pipe (PHP) is an inimitable passive two-phase energy conversion/transport device capable of transferring extensive heat energy by oscillating liquid slugs and vapour plugs from hot to cold areas suitable for the management of generation of heat in electronics. Several theoretical, experimental and visualisation studies are made on PHP to understand operational mechanisms and to arrive at optimal conditions. Although PHP has potential application in the field of heat management, its effective utilisation is limited due to complex operational mechanisms.It is observed that PHPs are effective and reliable devices for utilisation in numerous energy systems. It is observed that PHPs are effective and reliable devices for utilisation in numerous energy systems. Advanced research is directed towards numerical simulations on the evaluation of PHP performance with non-conventional working fluids. It is found that the use of ternary hybrid nanofluid in PHP has scope for research work. The objective of this paper is to review the existing methodologies for enhancing the PHP overall performance and its applications. [ABSTRACT FROM AUTHOR]

Efficient energy conversion can improve Pelton turbine unit efficiency and bring higher economic benefits. However, the reasons that influence the energy conversion characteristics of the Pelton turbine have not been effectively revealed. The main reason is the lack of systematic research on the change process of flow patterns in the bucket and its relationship with the energy conversion characteristics. Experimental and numerical simulation studies of a Pelton turbine were conducted. The change process of the flow patterns from when the jet enters the bucket to when it is completely discharged is analyzed and three main flow patterns in the buckets are summarized. Through energy characteristic analysis, it was found that during the power change process of the bucket, the flow rate entering the bucket and the velocity moment at the inlet of the bucket shows a trend of first increasing and then decreasing, while the velocity moment at the outlet of the bucket and flow loss show an opposite trend, resulting in the most sufficient energy conversion when the jet is perpendicular to the bucket. The basic topology of the bucket energy conversion process is constructed to effectively understand the Pelton turbine's energy conversion characteristics. [ABSTRACT FROM AUTHOR]

The use of multilevel power converters for its application in high demanding industrial processes and grid connected renewable energy conversion systems has nowadays become the most suitable solution. The main advantages of these converter configurations are: reduction in the blocking voltage stress, lower harmonic ratings, smaller filters for output and input stages. The proposed quasi-nested topology merges the advantages of the classical multilevel topologies, such as the NPC and ANPC configurations, addressing less active switching devices, lower blocking voltage stress. A novel discontinuous modulation technique, with controlled discontinuous gain, is implemented in order to deal with the dc-link voltage unbalance. Simulation and experimental validation results in a scaled-down power 1,5 kW three-phase converter prototype under different operational conditions using different modulation index are presented. The proposed four-level converter topology allows generating an additional output voltage level with the same semiconductor count as conventional three-level inverters such as NPC and ANPC with superior waveform quality, with a THDv reduction of 34.54% in comparison to the clamped inverters. Experimental tests carried out in a 1.5 kW setup verify the feasibility of the proposed topology and the developed discontinuous modulation scheme, to achieve dc-link voltage compensation. [ABSTRACT FROM AUTHOR]

Fe-based spincrossover (SCO) molecular complexes have shown to exhibit spincrossover behavior when subjected to stimuli such as heat, light and pressure. In a previous work, solutions of Fe-based spincrossover (SCO) molecular complexes with increasing ligand length, CnH2n+1NH2 (n = 12, 14, 16) of Fe(L12)2](BF4)2, [Fe(L14)2](BF4)2, and [Fe(L16)2](BF4)2, have shown to produce ultrahigh Seebeck coefficients when subjected to a temperature gradient. In this work, these three compounds are dissolved in dimethyl sulfoxide (DMSO) and subjected to temperature dependent Ultraviolet-visible (UV-vis) spectrometry. This optical characterization method was used to provide a correlation between the ligand length of the SCO complex and the bandgap energy measured. Subsequently, these findings were also triangulated with the effect of the ligand length on ionic conductivity and the Seebeck voltage. This work thus provides a systematic molecular understanding of the optical and electronic characteristics of SCO complexes, which paves the way for molecular design strategies in utilization of SCO for applications such as energy conversion and sensors. [ABSTRACT FROM AUTHOR]

Most of the developed and developing countries focused on the renewable energy sources conversion into alternate energy sources to compete with the depletion of conservative resources. The quality of this energy should be high because it will be used in every nook and corner of the world. The most applicable renewable source of energy is solar, which can be getting directly from the sun by a solar photovoltaic array. The power from the SPV array is irregular, so there is a need for DC-DC converters to generate the regulated constant power. This proposed work developed a Modified Super Lift Luo Converter (MSLLC) with high energy conversion. This converter is more effective than existing converters and it can also boost up the voltage up to 8.17 times the input voltage. The proposed MSLLC converter can attain better efficiency at 93.94% at 1000 W/m2 irradiance. [ABSTRACT FROM AUTHOR]

Energy transfer accompanying with current is usually described by using Poynting's vector. Here, combining Kirchhoff's law, Joule's law and Slepian's postulation, we demonstrate that, for the case of a current travels along a wire, component of total energy flow flux parallel to the wire (CTEFFPW) may be equivalently described by using product of current intensity and electric potential (voltage), furthermore, the law of conversion and conservation of energy accompanying with current, which is equivalent to Poynting's theorem, may be obtained based on circuit method. Noting that product of current intensity and voltage relates to CTEFFPW instead of the electric power, physical meaning of usual definitions of powers adopted in electric power theory are readdressed. Our work may provide possibility to achieve the long-time expectation that power properties of power systems are described on the basis of Poynting's theorem and Poynting's vector, and to address the unsolved problems arised in the electric power theory. [ABSTRACT FROM AUTHOR]

Prediction of the mechanical to electrical energy harvesting capabilities in [011]C cut PIN-PMN-PT is presented as a function of thermodynamic analysis of hysteresis in the stress induced ferroelectric phase transformation, and phase dependency of the electromechanical coupling factors. Energy conversion rates vary from 0.528 for low transformation hysteresis to 0.432 for high transformation hysteresis. While these predicted values are lower than the experimentally determined value from literature ("approximately 60%"), differences are explained through limitations of the mechanical loading mechanism. This brings the predicted values into agreement with literature. Ferroelectric rhombohedral phase behavior is found to dominate energy harvesting capabilities. [ABSTRACT FROM AUTHOR]

Phenomenology theory of ferroelectrics is developed to solve pyroelectric energy conversion performances in Olson cycle by using rotation and coupling of dipoles depending on temperature and electric field. Numerical simulation shows electric field related pathway of cycle. The conversion efficiency of an Olson cycle has a peak at temperature over Curie temperature, which is higher for increased low temperature point. A horary conversion efficiency is developed to compare conversion efficiencies in different temperature range. The conclusion is that the horary efficiency is higher when the low temperature point is higher and the high temperature is lower. [ABSTRACT FROM AUTHOR]

Megawatt solar plants are the reality now with nations looking for GW installed capacity. This high power is possible because of increased power levels in photovoltaic (PV) energy conversion systems. The multilevel converter (MLC) is the emerging technology for interfacing medium and higher voltage grids. This paper gives the design and analysis of transformerless grid interfaced single-stage 43-level Cascaded H-bridge (CHB)-based MLC for integrating large-scale solar PV plants with improved Total Harmonic Distortion (THD). Transformerless integration and reduced filter size, due to improved THD, contribute appreciable savings in the Capital Expenditure and Operation and Maintenance cost of the big solar PV plant. This paper also showcases the design-based strategy for deciding the levels used in the MLC, making it both efficient and economical. The control scheme comprises voltage-oriented control (VOC) with synchronous reference frame (SRF) and phase-locked loop (PLL). The low-frequency phase-shifted pulse width modulation (PWM) suitable for the cascaded MLC is used for modulation. The separate incremental conductance (InC) algorithm is used for the extraction of maximum power from each solar PV array. This algorithm takes care of the unforeseen insolation level changes, shading effect, ambient temperature, and other related factors of the multi-string SPV system. The simulation is performed in MATLAB/Simulink and validated on an OPAL RT simulator. Both steady-state and dynamic behaviors at different insolation levels of the considered system are studied. The performance is validated as per the IEEE-519 standard requirement. Decent decrease in THD of grid current is observed with low switching losses. [ABSTRACT FROM AUTHOR]

Reasonable development and utilization of wave energy as a useful supplementary way to resolve the energy crisis has a great significance for energy structure adjustment. Due to increasing attention on energy security insurance, ecological environment protection, and climate change adaptation, various works have been performed in this area. However, compared with the other renewable energies, more research is required on reliability, security, or overall cost. The purpose of this study is to review of current research status and challenge for direct-drive wave power take-off system especially for our research group, and some suggestions are given in the conclusion section to accelerate the advancement of the wave power take-off industry. The advantages and disadvantages of various devices are summarized. [ABSTRACT FROM AUTHOR]

The energy conversion performance of thermophotovoltaic (TPV) systems can be improved when the vacuum gap between the emitter and the TPV cell is at the near-field owing to the photon tunneling of evanescent waves. Among them, the back-gapped-reflector TPV systems have gained interest as a method of improving their conversion efficiency by optimizing the spectral absorption of TPV cells. In this work, we introduce an alternative concept for the back-gapped-reflector TPV systems, namely the medium-bridge near-field TPV system, by building a medium bridge between the metal reflector and the TPV cell using SU8 nanofilm. The SU8 medium-bridge achieves a noticeable improvement in output performance by increasing the spectral absorption of the InAs cell and reducing parasitic absorption losses of the Au substrate. The results indicate that, as a consequence of the improved effect of the medium-bridge, the output power density and efficiency of this system exceed those of the conventional TPV system (which lacks a medium-bridge) by 26.4% and 36.5%, respectively. Moreover, we systematically analyze the modulation of medium-bridge thicknesses and cell thickness on output performance and clarify how both affect energy losses of this near-field TPV system. Our work offers a strategy to improve the energy conversion performance of the near-field TPV system, opening new opportunities for developing near-field energy conversion. [ABSTRACT FROM AUTHOR]

Thermoelectric (TE) technology is considered as one of the promising, eco-friendly, simple and sustainable technologies to generate electricity directly from waste heat and concentrated solar heat. The present TE generators/devices are operating with very low conversion efficiency. Therefore, understanding the electronic and thermal properties of TE materials plays a vital role in enhancing device efficiency. In addition, non-toxic and abundant materials are also important to implement TE technology for large-scale applications. In the past few decades, a lot of research has been done on finding various oxide-based thermoelectric materials. Among many oxide-based materials, oxychalcogenides have received a lot of attention due to their useful thermoelectric properties. This review provides insights into thermoelectrics of selected inorganic oxychalcogenides. A comprehensive discussion has also been made on recent advances in preparation methods and various approaches such as doping, alloying, co-doping techniques adopted for design and optimisation of the TE materials. [ABSTRACT FROM AUTHOR]

Due to their distinctive electronic, mechanical, thermal, and optoelectronic properties, two-dimensional (2D) materials have emerged as valuable alternatives for thermoelectric (TE) materials. Recently, graphitic carbon nitride (g-C3N4), a metal-free semiconductor, has attracted attention in many applications, including energy conversion and storage. However, research on the use of g-C3N4 in TE applications is still limited. In this study, the TE properties of exfoliated g-C3N4-filled unsubstituted polythiophene (PTh) composites were determined for the first time. For this purpose, g-C3N4 was synthesized from guanidine-hydrochloride by thermal treatment, and the exfoliation process was carried out by ultrasonic homogenization method. The composites containing different weight ratios of g-C3N4 were prepared. The peak shifts observed from FTIR-ATR and UV-vis analyses indicated the electrostatic interactions between g-C3N4 and PTh. From the electrical conductivity measurements of the samples, it was obtained that the electrical conductivity of the pristine PTh increased from 1.3x10−3 Scm−1 to 100.1 Scm−1 whereas the Seebeck coefficient increased from 9.5 µVK−1 to 116 µVK−1. Additionally, the power factor of the pristine PTh increased from 1.28x10−5 µWm−1K−2 to 85.81 µWm−1K−2. Based on the results, this study suggests that g-C3N4 is an efficient material to be used as an additive to enhance the TE properties of PTh. [ABSTRACT FROM AUTHOR]

3D printing has become a powerful technique in electrochemistry for fabricating electrodes, thanks to readily available conductive nanocomposite filaments, such as those based on carbon fillers (i.e., carbon nanotubes (CNTs) or carbon black (CB)) within an insulating polymeric matrix like polylactic acid (PLA). Inspired by inorganic heterostructures that enhance the functional characteristics of nanomaterials, we fabricated hetero-layered 3D printed devices based on carbon allotropes using a layer-by-layer assembly approach. The heterolayers were customised through the alternate integration of different carbon allotrope filaments via a multi-material 3D printing technique, allowing for a time-effective method to enhance electrochemical performance. As a first demonstration of applicability, CNT/PLA and CB/PLA filaments were utilised to construct ordered hetero-layered carbon-based electrodes. This contrasts with conventional methods where various carbon species are mixed in the same composite-based filament used for building electrochemical devices. Multi-material 3D-printed carbon electrodes exhibit improved electrochemical performance in energy conversion (e.g., hydrogen evolution reaction or HER) and sensing applications (e.g., ascorbic acid detection) compared to single-material electrodes. This work paves the way for manufacturing advanced 3D-printed heterolayered electrodes with enhanced electrochemical activity through multi-material 3D printing technology. [ABSTRACT FROM AUTHOR]

Additive manufacturing is increasingly utilised in the energy conversion and storage field. It offers great flexibility to fabricate structural materials with improved physical properties, and other advantages such as material waste reduction, fabrication time minimisation, and costeffectiveness. In this review, current developments in additive manufacturing of energy storage devices are discussed. The digital design approaches of structural materials and mainstream additive manufacturing techniques, including vat photopolymerization, powder bed fusion, material jetting, binder jetting, material extrusion, and directed energy deposition, are summarised. Then, a comprehensive review of recent advances in the electrochemical and thermal energy storage field is provided. In the end, an integrated framework considering digital design and additive manufacturing is proposed for a wide range of energy applications. [ABSTRACT FROM AUTHOR]

Pulse width modulation (PWM) is a very important application in the switch control of inverter and converter circuits in power electronics. In order to make a quality energy conversion, the control of the switches in multi-level inverters is usually done with Sinus Pulse Width Modulation (SPWM). With this PWM structure while creating high-level voltages, unnecessary operation of the switches and sources that make up the lower level is provided at some time intervals. This causes shortening of switch life and power losses due to extra source and switch operation. To solve this problem, a new Fractional Sinus Pulse Width Modulation (FSPWM) development with β gap on a signal processing method in three steps is presented. In the MATLAB Simulink application, after the development of the FSPWM is presented, the developed Fractional Sinus Pulse Width Modulation (FSPWM) is compared with the traditional SPWM, and it is shown how to mute switches and sources during unnecessary operating times. [ABSTRACT FROM AUTHOR]

The aircraft manufacturing industry faces a severe problem of machining distortion. Machining distortion is caused primarily by residual stresses. The energy conversion during the machining process is the essence of residual stress leading to machining distortion. This paper uses the energy principle to analyze the mechanism of machining distortion of long beam parts, pointing out that during stress redistribution, part of the strain energy is released to do work, and the result of stress redistribution is consistent with the principle of minimum potential energy. The energy concept is used to develop a theoretical model of stress redistribution. A theoretical model of stress redistribution based on the energy principle is proposed. A model is proposed for predicting machining distortion during the machining of long beam-like parts, and the model's accuracy is demonstrated using a case study. [ABSTRACT FROM AUTHOR]

Energy conversion and storage is the key avenue of research as the energy demand is growing with the life style and standard of living. Supercapacitors are important class of devices which convert and store chemical energy into electrical. Batteries differ with these devices with their capacity to deliver the stored energy. To tune performance of these devices, focusing on design of the electrode material is the key. Nano-materials, especially 2D with one or few atoms thick, contribute in a peculiar way by exhibiting unusual characteristics in this direction. Also, they exhibit many special properties such as highly chemically active edge sites relative to basal planes, high mechanical and chemical stability, etc. This review discusses fundamentals of supercapacitors and relevance of 2D nanomaterials especially metal phosphides as their electrodes. [ABSTRACT FROM AUTHOR]

Wireless monitoring sensor gradually replaces wired equipment for data support in petrochemical industry production. This paper presented a design of a thermoelectric generator (TEG) system-based petrochemical pipeline waste heat recovery for wireless sensor. The TEG is assembled using an easy-to-modify structure that can be mechanically adjusted to different pipelines. Besides, we designed a new zero-power, micro-vibration, and easy-to-install heat sink for TEG applied in high-temperature petrochemical pipelines. The proposed TEG prototype has been fabricated and tested. The experimental results show that the system proposed in this work can supply enough energy to sustain the operation of a wireless sensor node that measures petrochemical fluid temperature and pressure for precision industrial production applications. The minimum output power is 24.7 mW at the hot side of thermoelectric generation (TEG) temperature of 100◦C −190◦C. This work presents a promising, cost-effective new approach to the conversion of waste heat into electricity for self-powered sensor networks. [ABSTRACT FROM AUTHOR]

Vacuum dewatering is a highly energy-intensive process that is widely adopted in industrial production such as papermaking and chemical manufacture. A significant portion of the energy consumed by vacuum system is converted into energy that drives airflow passing through the wet fiber web. During the energy conversion process, a part of the energy is wasted due to the redundant capacity of the vacuum pump, which is caused by the deviation of the airflow rate estimation during the design of the vacuum system. To improve the energy conversion rate, a variable porosity model (VPM) is proposed in this study to better simulate the process of airflow passing through a porous medium–wet fiber web. Compared with the existing constant porosity model (CPM), the VPM model takes the effect of wet fiber web compressibility into account to improve the accuracy of airflow rate calculation. Different sets of experimental data demonstrate that the accuracy of airflow calculation of the VPM is about 22 times that of the CPM. In addition, the characteristic parameterization of different fiber structures in this study expands the applicability of the model and can be widely adopted in multitudinous industrial fields, which is of great significance for improving the energy conversion rate of vacuum dewatering process and saving energy. [ABSTRACT FROM AUTHOR]

This paper investigates the controller implementation and analysis of Doubly Fed Induction Generator (DFIG) for powering isolated loads in rural electrification. A simple speed sensorless algorithm-assisted controller for isolated power supply of DFIG has been proposed using a digital controller and voltage source converter at the rotor terminals of the generator. The controller can automatically correct the voltage and frequency of the rotor side inverter pulse to obtain a desired voltage and frequency at stator side despite the variations in the wind speed and load. A hardware prototype of the system has been built and tested on a prototype machine, which is driven by an emulated wind turbine under sub-synchronous and super-synchronous speed operations. The detailed results of both simulated and hardware waveforms are provided in the paper to demonstrate the working of the proposed topology and embedded control scheme. Further, the performance characteristics of DFIG are modeled and verified experimentally. A good agreement exists between theoretical and experimental results. [ABSTRACT FROM AUTHOR]

This paper presents development of a frequency up conversion piezoelectric energy harvesting system that takes cattle movement vibrations and convert it into electrical energy. The harvested power can be used to power some devices relating to cattle precision farming operations. The design should get excitation from cattle motion frequency in the range of 5-8 Hz and upconverts it to a much high resonant frequency of 47.2-76.05 Hz. A Finite Element Analysis (FEA) is modeled and studied using COMSOL Multiphysics. The model is expected to generate power sufficient enough to operate devices like pedometers which consume on average 1.8 V. [ABSTRACT FROM AUTHOR]

The buck converter is one of the DC/DC converters that are often used as power supplies and high energy conversion. These controllers are used in electronic devices to regulate the output voltage against change in the input voltage and load current. This leads to the requirement of an efficient control methodology to meet real-time demand. It is found in many works of literature that satisfactory performance in buck converter's dynamic behavior using genetic algorithm controlling techniques, but the appearance of the transient with large overshoots and the ripple output voltage is not focused. The main reason for such a problem is the improper selection of capacitance values. In this work, to address such issues, along with the PID controller gain values and capacitance selection also be considered in multi-objective problems. The optimization is carried out using the NSGA-II and modified NSGA-II algorithm. This paper also presents a comparison of these algorithms' performance in terms of time-domain specifications and ripple voltage. Simulated outputs exhibit that the controller based on MNSGA-II for buck converter gives better performance than NSGA-II-based controller and results compared with the existing wok. The MNSGA–II-based PID controller for buck converted validated in the real-time environment also. [ABSTRACT FROM AUTHOR]

The current study examines the influence of different hole transport layers (HTL) and electron transport layers (ETL) on an environmentally friendly CsSn0.5Ge0.5I3 based perovskite solar cell. The numerical analysis of a novel heterojunction structure of FTO/WS2/CsSn0.5Ge0.5I3/Zn3P2/Pt was done using SCAPS software. Initially, a suitable HTL (i.e. Zn3P2) and ETL (WS2) were chosen after analyzing various inorganic HTL and ETL materials. The optimized thickness values of the perovskite film and HTL layer were also measured. Different physical parameters of layers were also measured, such as defect concentration, radiative recombination, energy bandgap of the absorber layer, interface defect concentration, and series and shunt resistances. These analyses revealed that optimizing these parameters improves the electrical rendition of the Tin-Ge-based perovskite solar cell. The photovoltaic cell's energy conversion efficiency (ECE) value increased to 26.22%, current density (Jsc) to 27.182 mA/cm2, and open-circuit voltage (Voc) to 1.116 V, and fill factor (FF) to 86.40%. [ABSTRACT FROM AUTHOR]

The fast advancement of photovoltaic (PV) power generation technologies led to the integration of solar-based generation systems into several modes of transportation, including aircraft, automobiles, and trains. In these PV systems, solar irradiation levels fluctuate significantly and invalidate specific maximum power point (MPP) tracking (MPPT) control strategies, lowering the energy conversion efficiency. It is evident that the new robust model reference adaptive control (MRAC) proposed in this paper alleviates these problems by reducing tracking direction loss and oscillations near MPP. To evaluate the proposed controller's performance, MATLAB/Simulink is utilized and compared with well-known techniques (P&O, VSPO, INC, ANFIS, and swarm-based MPPT) under three different modes, i.e. stand-alone, grid-connected, and real-time mode. The proposed scheme has tracking efficacy lies between 99.02% and 99.96% and achieved MPP in just 4 msec under highly fluctuating radiation and temperature conditions. It takes only 0.08 sec to capture the global MPP, which is on average two times faster than swarm-based global MPPT methods. Furthermore, the effectiveness is tested in a 50 kW three-phase grid-connected mode with and without cloud effects in realistic weather situations. Finally, real-time validation on the OPAL-RT simulator demonstrates the proposed technique's practicality in real-world applications. [ABSTRACT FROM AUTHOR]

Renewable energies have gained momentum in energy transition agenda based on the benefit of lower emissions of carbon and its compounds. Many technologies have been developed at different technology readiness levels addressing climate change impact with reduced emissions of greenhouse gases such as CO2. Herein the perspective article, we have reviewed CO2 capture technologies, such as absorption, adsorption, membrane separation, cryogenic separation and separation via hydrate formation, with further focus on the possibility of utilising ocean thermal energy conversion (OTEC) power to generate green hydrogen and produce low carbon fuels. The potential of OTEC generated hydrogen to produce methanol was explored using a simulation exercise utilising a scenario from a real-life offshore gas production facility. By varying the catalysts and reaction conditions, the findings showed encouraging results of CO2 conversion of ≥50% and product yield of ≥80%. Considering single path reaction with 90%, 95% and 99% of recycling, the highest prediction of methanol production coupled with CO2 hydrogenation process was 276.59 metric tonnes per day (MTPD). In addition, based on the assumption of 13.5 million standard cubic feet per day (MMSCFD) of CO2 produced, 204 MW of OTEC power is required to convert approximately 97.82 MTPD of hydrogen for methanol production making it potentially an industrially viable process. [ABSTRACT FROM AUTHOR]

For a combustion-based thermophotovoltaic generator (TPV), the baffle-induced reacting flows are numerically investigated in the micro combustor with a multihole baffle representing a mixed feature of bluff body and multiple jets. The lobed flow feature is realized by the momentum difference between fuel and air streams and the baffle wall, not the geometrical conditions like a lobed nozzle. Compared with the H2–air combustor, the lobed flame and the votical structure are enhanced for the CH4–air combustor. To analyze the lobed structure, the lobe intensity and the equivalent perimeter are defined for the stoichiometric mixture line. The maximum lobe intensity is observed at the beginning zone of flame, whereas the equivalent perimeter is increased near the active reaction zone. As the baffle thickness decreases, the lobe structure is enhanced due to the increased vortices. Also, a close relationship between the maximum vorticities at the baffle exit and the maximized lobe structure is observed. The intensified lobe structure contributes to a shorter flame length and more efficient combustion, resulting in increased radiation available for a micro-TPV system. When the lobe structure is enhanced, the high emitter efficiency for an energy conversion device is obtained as 0.319–0.326 for the H2–air combustor. [ABSTRACT FROM AUTHOR]

The direct-drive Permanent Magnet Linear Generator (PMLG)-based Ocean Wave Energy Converter (OWEC) generates variable AC voltage, which cannot be directly utilized by the load. This paper presents a two-stage methodology to convert variable AC voltage to a constant amplitude AC voltage. First, a standard rectifier is used to convert variable AC voltage into variable DC voltage. After that, a cascaded buck-boost inverter is employed to achieve the constant frequency AC voltage. Systematic design and circuit analysis, along with working principle and voltage control strategy, are presented. A small scale laboratory prototype of PMLG associated with buck-boost inverter is developed to validate the proposed concept. [ABSTRACT FROM AUTHOR]

Wind power technology can contribute to the distribution system by regulating its active power output to enhance the system reliability. Additionally, it could be economically beneficial to improve voltage quality as well as load sharing with generation at various times, avoiding load shedding and risk of potential blackouts. However, output power of the wind turbine system is variable in nature and it is difficult to export this power into the distribution system without having any appropriate control strategy. To address this issue, a model predictive control (MPC) strategy has been proposed to regulate the voltage of the feeder to balance sinusoid and for power flow control, a reference phase angle delta is generated which maintains power balance at grid terminal during wind and load variations. Effectiveness of the proposed control strategy is investigated using MATLAB/Simulink simulation studies and a hardware design of a single-phase distribution system using dSPACE platform. [ABSTRACT FROM AUTHOR]

Due to the non-availability of model parameters, the model-base control of a nonlinear and infinite-dimensional underground coal gasification (UCG) process is a challenging task. In this paper, a robust neuro-adaptive sliding mode control (NASMC) is designed for the UCG process to maintain a desired heating value level. The unknown model parameters used in NASMC are estimated using the feed-forward neural network. Moreover, the controller also requires time derivatives of some model parameters, which are estimated by uniform robust exact differentiator. As the relative degree of the output with respect to the input is zero, therefore, to apply NASMC, the relative degree is increased to one. This approach maintains the desired heating value and provides insensitivity to input disturbance and model uncertainties. A comparison is also made between NASMC and an already designed conventional SMC. The simulation results show that NASMC exhibits better performance as compared to the conservative SMC design. [ABSTRACT FROM AUTHOR]

Dry-type transformers are one of the most significant devices used in the conversion, transmission and management process of the electricity. In practice, the electrical energy conversion entails energy losses such as heat, electromechanical and electromagnetic losses during the transformation. Hence, primary importance is the efficiency of energy conversion for a device that converts AC voltage from one value to another with the same frequency. Therefore, this study offers the best 3-phase dry-type transformer modelling interested in cost and efficiency related to transformer losses and useful energy conversion. Transformer manufacturing industries will produce a low cost and more efficient dry-type transformer by using electromagnetic/thermal analyzing and multi-optimization methods. Firstly, a 250 VA 380/110 V 3-phase cast resin core type transformer is modelled by an electromagnetic field simulator software programme called as ANSYS/Maxwell so the transformer is analyzed in detail in terms of the thermal and electromagnetic. In addition, the cost and efficiency values are optimized based on the current density (s) and C coefficient parameters by the multi-optimization method. Secondly, the transformer model is analyzed as thermal and electromagnetic at the end of the simulation results. Finally, the transformer is tested experimentally so the test results are confirmed by the simulation results considering the measurements. It is hoped that this study will contribute to transformer designers and operators interested in the conversion, transmission and management of the electrical energy. [ABSTRACT FROM AUTHOR]

A drum boiler is the most critical part of power generation plants. The control of a highly nonlinear, multiple input and multiple output drum boiler system (DBS) is a challenging task. In this work super-twisting sliding mode controllers (STSMCs) are designed for the control-oriented model of the DBS, which maintain a desired water level and pressure of the drum. The unknown state of the DBS required for the control design is estimated using a gain-scheduled Utkin observer (GSUO). A rigorous mathematical analysis is also included to show that the closed-loop system is locally stable. The simulation results show that the closed-loop system yields the required performance even in the presence of parametric uncertainty, process and measurement noises, and external disturbance. To make a fair comparison, a quantitative analysis is also carried out for STSMC and PI controllers. Both controllers consume similar control energy, but STSMC shows better tracking performance. [ABSTRACT FROM AUTHOR]

The efficient recovery and conversion of energy in oily sludge has great prospects. In this article, the main objective is to investigate the impact of the addition of CO2 during the pyrolysis of oily sludge on energy recovery and conversion by thermogravimetric analysis (TGA) and compare the effect with the traditional pyrolysis effect from the perspective of thermal conversion behavior, products composition, and kinetics analysis. The results of the experiment showed that in the CO2 atmosphere, the main weight loss temperature of oily sludge was mainly concentrated in the range of 300–500 °C, which is lower than the reaction temperature range of traditional pyrolysis. The yields of CO and H2 in the products have been greatly improved, and the highest proportion in the gas products can reach 19.29% and 22.38%, respectively. The Ea (activation energy) values of oily sludge were determined to be in the range of 40–120 kJ·mol−1 with the conversion between 0.2 and 0.8 via DAEM, KAS, Starink, and FWO methods, respectively, in which the FWO method has shown the strongest adaptability. The results of this study provide reference values for practical engineering applications. [ABSTRACT FROM AUTHOR]

The fabrication and experimental research of a GaN-Positive-Intrinsic-Negative (GaN-PIN) betavoltaic nuclear battery driven by an 63Ni radioisotope source and an SiC-Schottky betavoltaic nuclear battery driven by an 147Pm radioisotope source are introduced. The self-absorption effects of radioisotope sources (63Ni, 147Pm) are explored and analyzed by Monte Carlo simulation. The SiC-Schottky and GaN-PIN betavoltaic cells were fabricated, where the GaN-PIN devices include different areas, absorption layer thicknesses, and electrode structures. And the measured I–V results show that the power density of the GaN-PIN nuclear battery can exceed 4.3 nW/cm2, the open-circuit voltage can reach 1.25 V, and the energy conversion efficiency can reach 2.3%. And for the SiC-Schottky betavoltaic battery, the maximum output power and energy conversion efficiency are 0.67 pW/cm2 and 0.024%, respectively. [ABSTRACT FROM AUTHOR]

In the present paper we have investigated the impact of predator harvesting in a two-dimensional prey–predator model with Holling type III functional response. The main objective of this paper is to study the change of dynamical behaviour of the prey–predator model in the presence of non-linear predator harvesting. The model system shows complex dynamics with the change of different system parameters. We have established the positivity and boundedness of the solutions under a certain parametric condition with non-negative initial conditions. The existence and stability criterion of different equilibrium points are investigated in terms of system parameters. We have shown that the system undergoes through saddle-node bifurcation, transcritical bifurcation, Hopf bifurcation and Bogdanov-Takens bifurcation under different parametric conditions. The structural changes or the system bifurcations predict the global dynamics of the model system. We have computed the first Lyapunov number to find the direction of the Hopf-bifurcating periodic solution of the system. Using numerical simulation we have studied here the effect of conversion efficiency, protection of the environment to the prey population and non-linear predator harvesting on the model dynamics. Finally the paper is ended with some conclusions. [ABSTRACT FROM AUTHOR]

In this report, a physicochemical study was performed on a series of organic dyes (AE, AQ, TE, and TQ) in the gas phase and solvent through the molecular approach. Triphenylamine/dimethylaniline as electron donors and 1,1,4,4-tetracyanobuta-1,3-dienes (derived from TCNE)/ 2-(4-(4,4-dicyanobut-3-en-2-ylidene)cyclohexa-2,5-dien-1-ylidene)malononitrile (derived from TCNQ) as the electron acceptors were utilised in this system. The introduction of strong electron acceptors of TCNE and TCNQ elevates electron transfer processes and makes the suggested dyes favourable to be used in the dye-sensitized solar cell (DSSC). On the basis of the obtained results, TCNQ-adduct dyes (AQ and TQ) have the highest charge transfer distance, excited-state lifetime, and the lowest overlap of the electron–hole distribution in comparison with TCNE-adduct dyes (AE and TE). The analysis of the charge transfer indices shows the amplification effect of the solvents in comparison with the gas phase and DMF as the solvent represents the best performance. Also, the maximum electron transfer rate constant and minimum electronic chemical hardness belong to the TCNQ-adduct dyes. Finally, AQ and TQ as the dyes and DMF as the solvent are introduced as the most promising candidates to be applied in the DSSCs due to efficient charge transfer and electron transfer rate constant. [ABSTRACT FROM AUTHOR]