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Free‐piston engine generator is a new type of hybrid power device and is regarded as the next‐generation energy conversion device which can replace the traditional internal combustion engine. This paper focused on the combustion stability and combines experimental results to study the key factors affecting the stability of the free‐piston engine, such as ignition time, intake pressure, equivalence ratio, and operating frequency. The simulation results showed that as the ignition advance angle increased, the indicated mean effective pressure increased significantly and the coefficient of variation of the indicated mean effective pressure was effectively reduced from 15.55% to 1.02% as the advance in ignition time from −15 to −30°ECA. When the intake pressure was increased to 1.2 bar, the average value of indicated mean effective pressure reached about 5.15 bar. When the equivalence ratio was in the range of 1.0–1.4, the coefficient of variation of the indicated mean effective pressure can be kept below 10%. The indicated mean effective pressure decreased monotonically from 4.79 to 3.62 bar, and the coefficient of variation increased by five times as the engine speed increased as the engine speed increased from 1,000 to 2,500 RPM. [ABSTRACT FROM AUTHOR]

This work presents a novel architecture for the 31‐level asymmetrical DC voltage source configured diode switched multilevel inverter, which has a single phase and fewer components. Using asymmetric DC sources and an H‐bridge, the proposed topology generates a maximum output voltage of 31 levels. This 31‐level topology is suitable for both renewable energy source conversion (RES) and electric vehicle (EV) applications. This topology requires fewer total components, lower cost, and smaller size. Along with the numerous benefits of MLIs, reliability issues are critical due to the larger number of devices required to minimize THD. Several characteristics, such as total standing voltage (TSV), reliability, cost function (CF), efficiency, and overall power losses, are investigated for the developed 31‐level MLIs. The TSV and CF of the proposed MLI are critical factors in demonstrating that the proposed topology is cost‐effective when compared to other recent topologies. Many parameters are thoroughly compared and tabulated, as well as represented graphically. The suggested MLI has lower TSV and component demand. Total harmonic distortion complies with IEEE specifications. The reliability aspects were also calculated and validated. The proposed MLI is controlled by a fuzzy logis controller (FLC) to achieve efficient results. The topology is simulated in MATLAB/Simulink software under a variety of conditions and dynamic load changes, and a prototype with a dSPACE controller is also implemented. [ABSTRACT FROM AUTHOR]

The increasing global dependence on fossil fuels for energy has prompted researchers to explore alternative power generation sources that offer higher efficiency, cost-effectiveness, and low environmental impact. Developed countries have been making continuous efforts to reduce their reliance on depleting fossil fuel sources to curb carbon emissions. As a result, hydrogen has gained significant attention among researchers as a potential future fuel that meets all the necessary criteria. Many countries aiming for a hydrogen economy have invested in research on fuel cells. Among various fuel cells, the solid oxide fuel cell (SOFC) has emerged as a commercially viable power source at a small scale. This paper provides an extensive review of the components, materials, design, operation, and integration strategies of SOFCs with existing thermal-based power plants. The performance and prospects of various SOFCs in standalone and hybrid modes are summarized, along with the limitations. Additionally, the research and commercialization efforts that can enhance the potential applications of SOFCs as a sustainable and reliable system in the long term are outlined. [ABSTRACT FROM AUTHOR]

The choice of mechanical and electrical topologies can affect piezoelectric energy harvesting efficiency, but the problem of achieving high-efficiency energy conversion in energy harvesters stacked as cantilevers has not been perfectly solved. This study focuses on the topology of piezoelectric elements in a stacked vehicle suspension vibration energy harvesting device. Through theoretical analysis, the stress expressions of the excited and driven elements are derived. The stress of the piezoelectric elements is affected by the positions of the connection and excitation points. A stress model was established for a four-piece piezoelectric element connected by a thin light rod in ANASYS. The simulation results show that the average stress in the piezoelectric bending element model is maximum when the excitation and connection points are located at both ends of the free end. Compared with the middle position of the free end of the piezoelectric element, the average stress of the model is increased by 92.904%. Considering the difference in voltage generated by piezoelectric elements, four kinds of electrical topology are designed and analyzed experimentally. When the driven elements are connected in parallel and then connected in series with the excited element, the output power varied the least with the change of load resistance. The system produces a high power and offers a wide selection of load resistors. When the load is 26 kΩ, a single set of four piezoelectric elements produces 86.407 mW of output power. [ABSTRACT FROM AUTHOR]

The structural stability analysis of various phases of GeTMS3(TM=Sc, Fe, Zn) sulfide perovskite has been conducted utilizing the WIEN2k package. This investigation leverages density functional theory (DFT) within the full potential linearized augmented plane wave (FP-LAPW) method, employing GGA-mBJ potentials. The focus of this study has encompassed the computation of structural, magnetic, and optical attributes across distinct GeTMS3 phases. These materials have been identified as promising contenders for applications in photovoltaics and spintronics. The study reveals the stability of various phases, with the orthorhombic phase proving energetically favorable for GeScS3 and GeZnS3, and the tetragonal phase for GeFeS3. Magnetic analyses indicate favorable ferromagnetic behavior in GeFeS3 and nonmagnetic characteristics in GeScS3 and GeZnS3. Furthermore, electronic examinations unveil semimetallic and semiconducting behaviors in GeScS3 and GeZnS3 in the tetragonal, respectively, with GeFeS3 exhibiting a half-metallic nature in the orthorhombic phase. Optical properties illustrate their potential as light harvesters, displaying characteristics suitable for energy conversion applications. This study contributes to a deeper understanding of sulfide perovskite properties, offering insights into potential applications in diverse technological fields. [ABSTRACT FROM AUTHOR]

The strong coupling between fluid and electromagnetic field in the annular linear induction pump (ALIP) can gradually amplify small disturbance in the fluid field into large-scale vortices. The appearance of the vortices seriously affects the efficiency and reliability of the pump. An active flow control method based on the modification of the driving electromagnetic field is proposed to improve the flow stability. A simplified numerical model of the ALIP is established to simulate the threedimensional flow in the annular flow channel, and the internal electromagnetic field is modified by using the modulated surface current. The influences of the active flow control method on the flow behavior, pressure pulsation, and energy conversion are, respectively, investigated based on the simulation results. The results show that the modulated surface current can accelerate the vortical evolution. The size and strength of the vortices are suppressed in the modified electromagnetic field. The pressure pulsation low frequency at the ALIP's outlet is significantly reduced when the modulated surface current density reaches a certain level. The surges in the processes of energy conversion become more gentle within the control method, and the overall energy efficiency is slightly reduced even at the highest modulated surface current density. [ABSTRACT FROM AUTHOR]

Renewable fuels attract more attention owing to reduction of both air pollution and greenhouse gas emissions compared to fossil fuels. The free-piston engine generator is a new energy conversion with compact structure, multifuel combustion mode possibility, and less friction loss, and it can be applied to a variety of renewable fuels. This study investigated the effect of operating parameters on power generation and motion characteristics for free-piston engine generator. A test bench and a detailed and validated numerical model of the free-piston engine generator were presented. Results show that with the increase of the average velocity, the output power root mean square (RMS) and efficiency of the generator gradually increase. The output power RMS grows rapidly, whereas the generator efficiency gradually stabilizes. Under the same average velocity but different strokes and frequencies, the generator power and efficiency are the same. This result means that the multiple-point operating condition can achieve the same output power and generator efficiency goals. Moreover, the optimal operating conditions can be selected comprehensively, considering factors such as fuel properties, combustion efficiency, and performance. The influence of the generator on motion characteristics of the system under pure resistive load and high-frequency operation should be noted. [ABSTRACT FROM AUTHOR]

It is challenging to develop scalable and stable multifunctional catalysts for energy storage and conversion applications. To address the above challenges, we designed 3D macroporous nanosandwich-like aerogels using an in situ sol-gel assembly for 2D g-C3N4 nanosheet-supported NiCo2S4 nanoporous aerogels. The resultant in situ method not only assembles NiCo2S4 but also 2D g-C3N4 into the sandwich-like 3D network, allowing rapid ion and electron transport. The potential of g-C3N4 and NiCo2S4 in electrochemical energy storage and electrocatalysis is promising for improving its electrochemical activities. The synthesized 3D NiCo2S4/g-C3N4 (3%) composite aerogel electrode achieved a remarkable specific capacitance value, 1083 F·g-1 at 5 mA·cm-2 current density with 87.03% cyclic stability. Furthermore, the asymmetric electrochemical supercapacitor device was fabricated with a maximum specific energy of 43 Wh·kg-1, with outstanding electrochemical stability of about 97% over 10,000 charge/discharge cycles. In addition, NiCo2S4/g-C3N4 (3%) catalysts achieved 294 and 155 mV as oxygen and hydrogen evolution reaction overpotentials, respectively, at 20 and 10 mA·cm-2 current density values. This study provides a new method for the conversion of 2D sheets and 0D colloidal network into 3D macroporous nanocomposite aerogels in multifunctional applications. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries have delivered outstanding charge storage performance due to their high energy density and low cost and also more specialized energy conversion device for next-generation electrical appliances. Herein, we offered the ultrathin Ti3C2 MXene (titanium carbide) nanosheets/vanadium nitride (VN)@carbon (C) nanocomposites for lithium-ion storage application as a high-capacity anode material. The proposed anode material is Ti3C2 MXene nanosheets/VN@C composite as synthesized via chemical precipitation. The real-time half-cell of Ti3C2 MXene nanosheets/VN@C composite shows the excellent initial discharge specific capacity of 1237 mAh g-1 at a current density of 0.1 A g-1 with a reverse rate capacity of 685 mAh g-1. The high specific capacity of 645 mAh g-1 has been attained even after 500 cycles at a current density of 0.1 A g-1. This type of rich reverse rate capacity and stability of the anode electrode is responsible due to the high conductivities and surface areas of Ti3C2 MXene nanosheets/VN@C composite, which is provided easy accessibility of Li+ ions. [ABSTRACT FROM AUTHOR]

The rock chip information (shape, size, and particle size distribution) could comprehensively reflect the characteristics of rock mass and rock-breaking efficiency of TBM. This study is aimed at defining a novel index (effective rock-breaking ratio, P r ) to identify the rock-breaking efficiency of TBM based on the rock chip information. To evaluate this approach, a series of field sieving and measuring tests of rock chips was conducted at the water conveyance tunnel construction projects of China. The rock-breaking efficiency evaluation and tunneling parameter improvement of TBM were researched based on P r index. The results showed as follows: (1) from the perspective of energy conversion, the rock chip surface area was calculated through the rock chip cumulative volume distribution model. P r is used to evaluate the rock-breaking efficiency of TBM based on the proportion of surface area of rock chips with particle size larger than 5 mm; (2) P r has a good linear correlation with coarseness index (CI) and specific energy (SE), the higher the TBM tunneling efficiency, the larger P r and CI values, the less SE values; (3) P r increases at first and then decreases with the rise of thrust force of TBM. The optimal thrust force intervals for grade II and III surrounding rocks can be determined to improve the rock-breaking efficiency of TBM. Findings from this study are insightful in terms of accurately evaluating the excavation efficiency and improving the tunneling parameters of TBM. [ABSTRACT FROM AUTHOR]

Sb2Te3 alloys are promising thermoelectric materials because of their outstanding electrical transport properties in the midtemperature range of 500–700 K, while codoping with multiple elements has been successful to improve their thermoelectric performance. In this study, enhanced thermoelectric properties with a maximum thermoelectric figure of merit of 0.97 are reported for singly and lightly Pb-doped Sb2Te3 polycrystalline alloys (Sb2– x Pb x Te3). Very light Pb doping in the range 0.005 ≤ x ≤ 0.0125 in the Sb2– x Pb x Te3 alloys yielded significantly improved carrier transport properties and increased electrical conductivity while the Seebeck coefficient is decreased moderately, since the density-of-state effective mass is improved much. As a result, power factor for the Pb-doped Sb2Te3 is largely increased up to 3.7 mW/mK2 at 300 K. The lattice thermal conductivity decreased considerably owing to the additional point defect phonon scattering by the Pb despite slight doping. Consequently, a maximum thermoelectric figure of merit of 0.97 was obtained for Sb1.9875Pb0.0125Te3 (x = 0.0125) at 600 K, which is the highest reported value for singly doped Sb2Te3-based alloys. A maximum energy conversion efficiency was calculated to be 9.0% for a temperature difference of 350 K, which is higher than that for other singly or codoped Sb2Te3 alloys. [ABSTRACT FROM AUTHOR]

Evaporative cooling is an efficient approach for removing heat from nuclear reactors, solar power plants, solar panels, and energy storage devices, such as lithium-ion batteries and fuel cells. Nanotextured surfaces can provide improved evaporative cooling by increasing the total surface area to enhance the heat transfer rate and reducing the temperatures of local hotspots. In this study, we introduced rhombic dodecahedral zeolitic imidazolate framework-8 (ZIF8), a class of metal-organic frameworks, via impregnation to create nanotextured surfaces. The impregnation time was varied to obtain various thicknesses of ZIF8. We found that the increased surface area of ZIF8 improved convection cooling, which considerably reduced the temperature of the heated substrate. Air, mist (buoyant aerosols), and spray (inertial droplets) were independently used as coolants to compare the cooling performance of noncoated (bare) and ZIF8-coated substrates. Compared to the noncoated substrate, the optimal ZIF8 film yielded temperature reductions of Δ T = 13 °C and 10°C for air and spray cooling, respectively. [ABSTRACT FROM AUTHOR]

TiO2 has potential application prospects in the fields of environmental pollution control and energy conversion, while its characteristics including proneness to agglomeration and low activity affect practical applications. In view of this, P25 TiO2 and graphene were taken as raw materials to prepare the modified TiO2 catalyst. The modification mechanism of TiO2 was explained by characterizing the phase composition, microscopic morphology, and functional groups and analyzing the specific surface area and particle size. Then, the photocatalytic performance of the material was explored by taking methyl orange as the target to be degraded. Results show that TiO2 is well grafted to the laminated structure of graphene using physicochemical interactions among the introduced functional groups after modifying P25 TiO2 and graphene. This way, the 10.00 mg·L-1 methyl orange solution is almost completely degraded within 12 min at a reaction rate that is 1.81 times higher than that of P25 TiO2. Even after being used for 10 times, the performance still remains stable. The modification process is simple, and the method is reliable. Results can promote the practical application of TiO2 photocatalytic technology. [ABSTRACT FROM AUTHOR]

Offshore wind turbines (OWTs) are considered vital to the promotion of the development of renewable energy. Especially, floating OWTs can be deployed over a larger area than bottom-fixed OWTs. The floating OWTs, however, are vulnerable to vibration induced by disturbances and require a backup power supply in the case of power outage. On the one hand, various kinds of inerter-based devices have been proposed especially for vibration suppression of civil structures subjected to earthquake loadings. Recently, combined with electromagnetic devices, the inerter technologies have also been applied in the field of vibration energy harvesting such as point absorber wave energy converters. Thus, this paper proposes a novel floating OWT consisting of two bodies combined with inerter-based power take-off (PTO) devices which accomplishes vibration suppression and wave energy conversion at the same time. To investigate the vibration suppression and energy conversion capabilities of the proposed floating OWT with a variety of inerter-based PTO devices for ocean waves, numerical simulation studies employing WEC-Sim are conducted, and the performance of each system is compared for regular and irregular waves. Results show that the proposed floating OWT with the appropriately designed inerter-based PTO devices for the incident wave period has great potential for both vibration suppression and wave energy conversion in a specific frequency range. [ABSTRACT FROM AUTHOR]

Underground gas storage (UGS) is a crucial method for mitigating seasonal fluctuations in natural gas consumption. However, in China, UGS is primarily achieved through the conversion of abandoned gas reservoirs with limited storage capacity. Radial jet drilling (RJD) is an effective technology for the secondary development of depleted reservoirs. The multiorifice nozzle is a critical component that can efficiently break rock and create radial holes to increase gas production. In this study, we investigate the impact of nozzle structure on energy conversion efficiency through numerical simulations and experiments. Additionally, we design a swirling multiorifice nozzle and verify its effectiveness in field applications. Our findings indicate that the nozzle pressure drop and vorticity are primarily generated at the acute angle of the orifices. The number of forward orifices is directly proportional to energy loss, while the discharge coefficient and hydraulic performance initially increase and then decrease. Swirling multiorifice nozzle have fewer backward orifices, so they have less energy loss and a larger discharge coefficient. It has achieved better rock-breaking results in field applications. In conclusion, this study provides theoretical guidance and technical support for the secondary development of gas storage. [ABSTRACT FROM AUTHOR]

Plastics are cheap, lightweight, and durable and can be easily molded into many different products, shapes, and sizes, hence their wide applications globally, leading to increased production and use. Plastic consumption and production have been growing since its first production in the 1950s. About 4% of global oil and gas production is being used as feedstock for plastics, and 3-4% is used to provide energy for their manufacture. Plastics have a wide range of applications because they are versatile and relatively cheap. This study presents an in-depth analysis of plastic solid waste (PSW). Plastic wastes can be technically used for oil production because the calorific value of the plastics is quite comparable to that of oil, making this option an attractive alternative. Oil can be produced from plastic wastes via thermal degradation and catalytic degradation, while gasification can be used to produce syngas. Plastic pyrolysis can be used to address the twin problem of plastic waste disposal and depletion of fossil fuel reserves. The demand for plastics has continued to rise since their first production in the 1950s due to their multipurpose, lightness, inexpensiveness, and durable nature. There are four main avenues available for plastic solid waste treatment, namely, reextrusion as a primary treatment, mechanical treatment as secondary measures, chemical treatment as a tertiary measure, and energy recovery as a quaternary measure. The pyrolysis oil has properties that are close to clean fuel and is, therefore, a substitute to fresh fossil fuel for power generation, transport, and other applications. The study showed that plastic wastes pyrolysis offers an alternative avenue for plastic waste disposal and an alternative source of fossil fuel to reduce the total demand of virgin oil. Through plastic pyrolysis, plastic wastes are thermally converted to fuel by degrading long-chain polymers into small complex molecules in the absence of oxygen, making it a technically and economically feasible process for waste plastic recycling. The process is advantageous because presorting is not required, and the plastic waste can be directly fed without pretreatment prior to the process. Products of plastic pyrolysis are pyrolysis oil, a hydrocarbon-rich gas, with a heating value of 25-45 MJ/kg, which makes it ideal for process energy recovery. Hence, the pyrolysis gas can be fed back to the process to extract the energy for the process-heating purpose, which substantially reduces the reliance on external heating sources. [ABSTRACT FROM AUTHOR]

Supercapacitors are the cutting-edge, high performing, and emerging energy storage devices in the future of energy storage technology. It delivers high energy and produces higher specific capacitances. This research study provides insights into supercapacitor materials and their potential applications by examining different battery technologies compared with supercapacitors' advantages and disadvantages. Transition metal hydroxides (cobalt hydroxides) have been studied to develop electrodes for supercapacitors and their use in various fields of energy and conversion devices. Cobalt-based metal oxides and hydroxides provide high-capacitance electrodes for supercapacitors. Metal hydroxides combine high electrical conductivity and excellent stability over time. The metal oxides used to prepare the electrodes for supercapacitors are cobalt-based metal oxides and hydroxides. It is stronger than most of the other oxides and has tremendous electrical conductivity. Cobalt hydroxides are also used in supercapacitors instead of other metal hydroxides, such as aluminum hydroxide, copper hydroxide, and nickel hydroxide. This study gives a complete overview of the preparation, synthesis, analysis, and characterization of cobalt hydroxide thin film electrodes by using the electrochemical deposition technique, parameters measurements, important characteristics, material properties, various applications, and future enhancement in supercapacitors. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs), as a new generation of intrinsically porous extended crystalline materials formed by coordination bonding between the organic ligands and metal ions or clusters, have attracted considerable interest in many applications owing to their high porosity, diverse structures, and controllable chemical structure. Recently, 2D transition-metal- (TM-) based MOFs have become a hot topic in this field because of their high aspect ratio derived from their large lateral size and small thickness, as well as the advantages of MOFs. Moreover, 2D TM-based MOFs can act as good precursors to construct heterostructures with high electrical conductivity and abundant active sites for a range of applications. This review comprehensively introduces the widely adopted synthesis strategies of 2D TM-based MOFs and their composites/derivatives. In addition, this paper summarizes and highlights the recent advances in energy conversion and storage, including the hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, CO2 reduction reaction, urea oxidation reaction, batteries, and supercapacitors. Finally, the challenges in developing these intriguing 2D layered materials and their composites/derivatives are examined, and the possible proposals for future directions to enhance the energy conversion and storage performance are reviewed. [ABSTRACT FROM AUTHOR]

Slug flow is one of the most common flow patterns in the petrochemical industry. It will affect the normal operation of oil well surface pipelines and connected equipment, especially gas well multiphase flowmeters. The extant slug flow traps are complex in structure and limited in application sites. To reduce the influence of slug flow on gas-liquid two-phase measurement, a slug flow elimination device is designed based on the kinetic energy conversion method. The gas-liquid two-phase flow law inside the device and its energy loss are investigated using a combination of indoor experiments and numerical simulations. This study evaluates the device's working performance, including the flow pattern, pressure fluctuation, velocity distribution, and energy loss. The results show that the flow rate and pressure fluctuation of the gas-liquid two-phase flow are weakened after the device. And the flow pattern changes from intermittent slug flow to gas-liquid continuous flow. The pressure drop calculation method for the device is developed based on the share of different structures in the total pressure drop, with a prediction error of 20%. The slug elimination device is designed to provide a flow pattern basis for metering equipment, improve metering accuracy, and further promote the development of multiphase metering technology. [ABSTRACT FROM AUTHOR]

Summary: A solar heater with a variable speed circulation pump is analyzed based on the manufacturer's data sheet of the PV generator, the DC pump as well as the solar collector under a specific climate condition via ANN approach. Direct normal irradiance, global horizontal irradiance and ambient temperature data of Tabuk city were used for system analysis. The detailed electrical characteristics of PV generator are performed based on a single diode model and transient thermal modeling of the storage tank is performed based on the Crank‐Nicolson numerical method which is developed based on thermodynamic energy balance. Hourly electrical performance output of PV generator is predicted considering maximum power point as MPPT is part of the PV pumping system which optimizes the power output of from the PV module. An empirical curve fitting correlation that determines the performance of the DC pump is developed from the performance curve of the pump which is obtained from the pump manufacturer. Similarly, an empirical correlation that relates flow rate and head loss at the solar collector is developed from the solar collector's manufacturer data sheet. Hydraulic features of the system such as hourly flow output and hourly head loss at the collector are determined based on a developed algorithm. Furthermore, hourly thermal characteristics are determined based on the Crank‐Nicolson technique. The power of solar cells was highly dependent on voltage and radiation intensity. To evaluate the sensitivity of the PV arrays, an artificial neural network (ANN) was used and it was found that the ANN with an R2 of.9998 had an error of less than 5% for more than 97% of the data points. [ABSTRACT FROM AUTHOR]

Summary: Transition metal carbide/nitride (MXene) is an emerging two‐dimensional (2D) material in the field of energy storage and conversion due to the unique 2D structure and high ionic conductivity property, which has been extensively focused. However, the MXenes family possesses tremendous species variety and element composition with more than 90% of unknown family members. The traditional experimental methods always focused on single species, which is time‐consuming and not systematic enough. Currently, machine learning, as an emerging computer technology, provided an advanced technique to boost the application of the MXene family comprehensively. In this review, we comprehensively summarize and comment on the latest application progress of machine learning in the development of MXene materials, focusing on the internal mechanism between machine learning and material development. Applications of MXene in the field of battery, supercapacitor, biological, and catalysis were fully reviewed. It can open up a new road map for the development of MXene materials in the new era. [ABSTRACT FROM AUTHOR]

Summary: The batteries fuelled by radio‐isotopes have represented a significant technological solution for planetary science and exploration missions since the beginning of the space era. Now emerging researches and new concepts are making the nuclear batteries attractive also for relevant terrestrial applications. The present survey aims to summarize the evolution of technical programmes and to examine the multidisciplinary skills required to accelerate the transition of nuclear batteries from laboratory prototypes to fully functional systems. [ABSTRACT FROM AUTHOR]

Summary: This paper characterizes an integrated hybrid energy storage unit required to support the new generator excitation system developed for doubly‐fed induction generators in the split‐shaft wind energy conversion units. The goal is to improve the power quality while significantly reducing the generator excitation power rating and component counts. The rotor excitation circuit is modified to directly include the storage to its DC link. The output power fluctuation can be attenuated solely by utilizing the rotor‐side converter making it self‐sufficient from the grid connection. The storage characteristics are identified based on several system design parameters, including the system inertia, inverter capacity, and energy storage capacity. The obtained power generation characteristics suggest an energy storage mix of fast‐acting types with a high energy capacity and moderate acting time. A feedback controller is designed to maintain the charge in the storage within the required limits. Adaptive model‐predictive control is also developed to reduce power generation fluctuations. The proposed system is investigated and simulated in MATLAB Simulink at different wind speeds to validate the results and demonstrate the system's dynamic performance. It is demonstrated that the system's inertia is critical to damping the high‐frequency oscillations of the wind power fluctuations. It is also shown that the bandwidth of the control system is determined by the system inertia and the size of the storage and inverter power rating. [ABSTRACT FROM AUTHOR]

Summary: Power performance of pneumatic motor (PM) limits its application in compressed air vehicle (CAV) as an auxiliary power. This study presents an investigation of the power system with parallel operation mode based on experiments to improve the power performance of PM. First, the test bench of PM in parallel operation mode is built. Then, a series of experiments are conducted to investigate the effect of key parameters on the power performance, economy and energy conversion efficiency of CAV. The interaction among the key parameters of the PM and the influence of them on the power performance are discussed. Subsequently, the power performance, economy and energy conversion efficiency of the PM working in single and parallel operation modes are compared. Experimental results show that the maximum power output of the PM is 979 W, and the energy conversion efficiency of PMs 1 and 2 are 6.54% and 6.80% when the PM works in parallel operation mode. The parallel operation mode of PM can improve the power performance, economy and energy conversion efficiency of CAV. [ABSTRACT FROM AUTHOR]

Summary: Solid oxide fuel cell (SOFC) found to be promising alternative energy conversion technology due to its higher efficiency, flexibility of fuel uses and environment friendly. However, conventional SOFC requires high operational temperature, increasing the cost and degradation of the cell components. The current work demonstrates the synthesis of nanocomposite Fe0.2Ni00.3Cu0.5 by solid state method to be studied as anode for low‐temperature SOFC. Due to the earnest effect of graphene and its derivatives, graphene oxide (GO) has been incorporated in order to enhance the properties of the prepared Fe0.2Ni00.3Cu0.5 anode to lower the operating temperature, at reduced cost for market acceptability. The crystal structure and surface morphology of prepare material was investigated by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). Thermal gravitational analysis TGA and Fourier transform infrared FTIR were further employed to observe the thermal and functional behavior of prepared materials. The crystalline size was found to be 17‐41 nm and results were validated by SEM analysis. Conductivity measurements were carried out by DC four‐probe method in temperature range 300°C to 600°C and maximum conductivity was calculated as 43 S/cm. The peak power density of fuel cell has been achieved as 529 mW/cm2 for Fe0.2Ni00.3Cu0.5 incorporated with 1.5 wt.% GO using H2 fuel which is enhanced value comparable to the base composite. The graphene‐incorporated FNC materials can be suggested as the cost‐effective potential candidate as anode for low‐temperature SOFC. [ABSTRACT FROM AUTHOR]

Summary: The study presents an iterative structure for optimal allocating roof space to photovoltaic panels and solar water heaters to provide part of the energy demand of the building and supply the excess energy to the grid. This framework is based on a mathematical programming model and consists of six stages: demand model, optimum tilt angle, selection of energy conversion technologies, near shadow, planning and operation, and evaluation with a detailed model. The output of the proposed model is the optimal arrangement of photovoltaic panels and solar water heaters, type and capacity of cooling system, and operational issues including energy exchange between solar systems, electricity grid, natural gas network, and building and capacity factor of water circulation pump working between solar water heater system and central cooling‐heating system in each time step. Various constraints such as full supply of the building's energy demand, limited allocated space to solar systems installation, limited financial resources for investment in solar systems, technical constraints, etc, have been considered in this model. Eight different scenarios in terms of energy carriers prices, guaranteed renewable electricity purchase tariff, circulation pump operational cost, and investment costs for solar systems were examined. The results of using the proposed model on an office building show a water‐cooled absorption chiller cooling system is the optimal option with the ability to satisfy technical constraints. If the electricity generated from the photovoltaic panels cannot be sold to the grid, only the installation of solar water heaters with a capacity of 29 kW is optimal. In this case, the annual capacity factor of the system, considering the hot water demand, solar irradiation, and cost of running the pump, is 22.7%. Suppose it is possible to sell electricity to the grid due to a higher sale tariff than purchase one in Iran, in that case, only the solar panels with a capacity of 8.75 kW will be installed on the roof. [ABSTRACT FROM AUTHOR]

In order to investigate the loading rate effect of energy evolution in granite, the indoor physical simulation test of single face fast unloading-three directions and five faces stress-vertical continuous loading under different loading rates was conducted using a new true triaxial rockbursttest system. The energy accumulation-dissipation-release characteristics in the process of rock deformation and failure were revealed. Based on the three-dimensional discrete element theory and the polycrystalline modeling technique (randomly generated Voronoi mineral grains), the entire process of rockburst inoculation-occurrence-development, as well as the energy evolution characteristics under true triaxial single face unloading conditions, were studied. The test results indicate that the energy transport and conversion of rock samples under different loading rates exhibit distinct stage characteristics. It can be divided into the initial energy accumulation stage, steady energy accumulation stage, rapid energy dissipation stage, and rapid energy release stage. With a rise in loading rate, the specimen in the process of energy accumulation is accompanied by energy dissipation, more external input energy, and elastic strain energy release amount into the kinetic energy of fragments, resulting in the rockburst phenomenon. As the loading rate increases, the elastic strain energy conversion rate (Ue/U) falls, while the dissipative energy conversion rate (Ud/U) increases. The higher the elastic strain energy conversion rate and the lower the dissipative energy conversion rate, the more serious the rockburst occurs. Numerical simulation results show that the entire process of rockburst inoculation-occurrence-development is successfully simulated using the crystal scale fine model (CSFM) considering the grain mineral composition. The ejection failure process can be divided into four stages, including grains ejection, rock spalling into plates, rock shearing into fragments, and rock fragments ejection. The relationships between the peak strength, elastic strain energy of rock samples, and loading rates are obtained, which is consistent with the laboratory test results. The high rate linear growth of kinetic energy evolution between the two inflection points can provide precursor information for rockburst prediction. [ABSTRACT FROM AUTHOR]

The energy conversion units and energy storage equipment connected to the multi-energy system are becoming diversified, and the uncertain factors brought by distributed wind power and photovoltaic power generation make the system energy flow structure more complex, which brings great difficulties to the modeling and application of traditional energy hub modeling methods. This study deeply analyzes the multi-energy flow coupling structure and operation mechanism of multi-energy systems, and carries out the power flow calculation and analysis of multi-energy systems based on an energy hub, so as to ensure the safe and stable operation of regional energy. Based on the physical characteristics of energy systems such as power systems, thermal systems, and gas systems, this article studies the comprehensive power flow model including the electric-gas-thermal multi-energy coupling network and proposes the power flow decomposition of the energy supply subsystem and its applicable equation based on Newton–Raphson method. The effectiveness of the proposed method under different operation modes is verified by case studies. The calculation results show that under constant load, the energy hub running in fixing thermal by electricity (FEL) and fixing electricity by thermal (FTL) mode has little influence on the voltage of each node in the power sub-network. Within the constraint range, the natural gas flow obtained from the natural gas subsystem is coupled with the power subsystem to meet the load demand. The influence on the power flow at each node of the heat network is not obvious. [ABSTRACT FROM AUTHOR]

Summary: Recent research has focused on the optimal current‐collector design of a large Mg anode for large‐scale Mg‐air primary batteries. The study investigated the effects of different current‐collector contact points (CCPs) on the electrochemical discharge performance and degradation of Mg anodes. The results revealed that the selection of CCPs on the Mg anode plays a critical role in improving the discharge capacity and power characteristics. The current values measured at several anode surface locations varied significantly depending on the CCP position on the Mg anode. This nonuniform current distribution is considered to be the major cause of undesirable degradation of the Mg anode upon discharge. Through numerical simulation based on electric field analysis, optimum multiple CCPs were designed to minimize the Mg anode degradation during the discharge process by alleviating the locally concentrated current in the vicinity of the CCPs of the Mg anode. The Mg anode with multiple CCPs exhibited a highly improved discharge capacity (46.2 Ah) and energy conversion efficiency (42%) compared to the Mg anode with single CCP (38.7 Ah and 35.2%). The multiple contact strategy and improved understanding of the correlation between the current distribution and anode degradation phenomena can be further applied for the optimal design and performance improvement of various types of metal‐air batteries, including Li‐, Al‐, and Zn‐air systems. [ABSTRACT FROM AUTHOR]

Summary: In accomplishment of massive energy demand, the solid oxide fuel cells (SOFCs) have proven as apotheosis candidates due to their high energy conversion efficiencies, low pollution exhaust, fuel flexibility, and environmental friendliness which make these the most promising alternatives to conventional electricity generators. Despite numerous advantages of SOFCs, large‐scale industrial applications are yet to be realized owing to their high operating temperatures (800°C‐1000°C). To lower the operating temperature, it is crucial to minimize ionic resistances which can be accomplished by reducing the electrolyte thickness to lesser than 5 μm. Therefore, present article embraces a concise review on conventional materials, designs, and generations of SOFCs with their compatibility and drawbacks. The strengths and limitations of conventional and advanced tools for fabricating thin film based SOFCs (TF‐SOFCs) as well as the associated properties of electrolytes and electrodes are thoroughly examined, and further route cast is provided to attain better performance. The present review encourages the development of TF‐SOFCs using advanced techniques employing ultrathin single and bilayer electrolytes which can have potential to reduce the operating temperature of SOFCs from 450°C to 600°C region and pave the way for global commercialization. [ABSTRACT FROM AUTHOR]

Aiming at the impact process of a fuel tank, which is a transient energy conversion process, the material absorbs energy through deformation to analyze the mechanical properties of the fuel tank during the impact process. The defense node method is adopted to simulate the dynamic response of the fuel tank during impact. The results show that it can accurately evaluate the safety of the container. [ABSTRACT FROM AUTHOR]

Nickel sulfides have unique and diverse structural features, making them ideal for energy conversion and storage. This research focuses on the synthesis and characterization of nickel sulfide thin films and nanocrystals from nickel ethyl xanthate complex using spin-coating and solventless methods. The nickel ethyl xanthate complex (C6H10S4NiO2) was characterized using Fourier-transformed infrared (FT-IR), ultraviolet-visible (UV-Vis), and nuclear magnetic resonance (NMR) spectroscopies as well as thermogravimetric analysis (TGA). The NiS thin films and nanoparticles were analyzed with energy dispersive X-ray (EDX) spectroscopy and X-ray diffraction (XRD). Nickel ethyl xanthate was synthesized in an 81.2% yield. The bandgaps of the nickel sulfide obtained from the spin-coating method ranged from 4.35–4.88 eV. For the solventless method, the bandgap of the nickel sulfide ranged from 3.93–3.96 eV. The crystal phase observed from the spin-coating and solventless methods was α-NiS (hexagonal). A direct correlation was observed between annealing temperature, bandgap, and particle size. [ABSTRACT FROM AUTHOR]

Confining pressure is closely related to the deformation and failure characteristics of gas-containing coal and is one of the key factors for gas outburst-rockburst coupled dynamic disaster. Firstly, this paper briefly summarized the triaxial compression test results of gas-containing coal under different confining pressures, including deformation and stiffness and failure and strength. Then, based on the second developed MatDEM gas-solid coupling program, the macro- and microdeformation and failure process of coal samples under different confining pressures and constant gas pressure were simulated, and the distribution of particle stress, pore stress, and crack, as well as energy conversion characteristics, was obtained. Finally, the influence mechanism of confining pressure on deformation and failure of gas-containing coal was discussed, and the occurrence conditions of coal and gas outburst, rockburst, and their coupled dynamic disasters were distinguished. The results show that the peak strength and residual strength after failure of gas-containing coal both increase approximately linearly with the increase of confining pressure, while the elastic modulus does not change much or increases continuously, which is closely related to the number of microdefects in the coal sample. The strengthening effect of confining pressure on rock stiffness and strength mainly comes from external support and compaction. The total number of cracks decreases with the increase of confining pressure, while the number of shear cracks increases, and the inclination angle between the formed macroscopic main crack and the horizontal plane gradually decreases. The maximum cumulative elastic energy and residual elastic energy both increase with the increase of confining pressure, which leads to the increase of the impact tendency index of coal samples. [ABSTRACT FROM AUTHOR]

The coal-rock projectiles induced by gas explosions in coal mines have a strong destructive effect on mine facilities and equipment, which are mostly made of steel. The LS-DYNA is used to simulate the process of coal projectile striking the steel plate. The results show that during the failure process, the morphological change of the projectile consists of three stages including plastic deformation, partial crushing, and complete crushing, and the steel plate pits at the impact point. The duration of the stress peak value of the steel plate increases as the impact velocity increases. The farther away from the center point, the smaller the stress peak value is, and the shorter the duration is. When the impact velocity is 100 m/s and 300 m/s, the axial velocity curve at the impact point of the projectile is pulsating. When the impact velocity reaches 500 m/s, the axial velocity of the projectile rapidly increases and then tends to be stable. As the impact velocity increases, the energy absorbed by the steel plate increases, and the rate of increase also increases. However, the proportion between the absorbed energy of the steel plate and the initial kinetic energy of the projectile decreases. The projectile conversion energy of the 1 mm steel plate is slightly larger than that of 1.5 mm and 2 mm steel plates, and the energy absorbed by the steel plate decreases with the increase in thickness of the steel plate. When the thickness of the steel plate is more than 2 mm, the thickness of the steel plate has little effect. The results of the study have a direct sense for the antiknock design of coal mine facilities and equipment. [ABSTRACT FROM AUTHOR]

This paper proposes a study on the potential of waste-to-energy (WTE) possibility in the Arab Republic of Egypt. WTE is a viable option for municipal solid waste (MSW) management and a renewable energy source. The issue of waste spread is a chronic environmental challenge in the Arab Republic of Egypt. The MSW practices in Egypt are simply done by collecting the waste and dumping it in open landfill sites. This research aims to assess the potential contribution of the WTE facility to meet electricity demand in Cairo City, which is Egypt's capital and the biggest city in population as a sample, and then apply the results to all of Egypt. The paper introduced a step-by-step calculation for the electrical power that can be generated from Cairo MSW. Four scenarios for WTE utilization were developed: Mass Burn without any waste processing, Mass Burn with 25% recycling, Mass Burn excluding 50% of organic material, and Mass Burn excluding 50% of organic material with 25% recycling. The Mass Burn scenario implies full MSW stream incineration; the Mass Burn with recycling scenario considers a partial separation of reusable materials and the waste leftover for incineration; the Mass Burn with excluding 50% of organic material scenario considers a partial separation of organic materials and the waste leftover for incineration; the Mass Burn with excluding 50% of organic material with 25% recycling scenario considers a partial separation of organic materials and partial separation of reusable materials and the waste leftover for incineration. The analyses were done for the period 2011–2031 for Cairo with a total population of about 10 million in Nov 2021. The results show the huge potential of WTE conversion as a source of renewable energy, which is a key factor in Egypt's sustainable development strategy 2030. Available data have been theoretically processed to show the decision-makers in Egypt the amount of electrical power that can be generated by using the WTE options to manage the MSW in Egypt. [ABSTRACT FROM AUTHOR]

Summary: Scattered energy sources are essential to advance sustainable systems with the development of small‐sized devices. Thermopower waves (TWs), which use self‐propagating combustion along micro‐nanostructured composites, can directly convert thermochemical to electrical energy, thereby resolving the configuration limits in small dimensions. However, poor sustainability and energy density, induced by short duration of the combustion should be addressed, although TWs exhibit high‐power densities. Herein, we report the use of formaldehyde (FA)‐activated multi‐walled carbon nanotube (MWCNT) and Sb2Te3 composites to achieve ultrahigh TWs enabled by the remarkable enhancement of the sustained time and the chemical energy conversion. The FA supports sustained and amplified TWs through its chemical reaction pathways, while the MWCNTs and Sb2Te3 serves as thermal conduits and thermoelectric materials to generate TWs. The weight ratio of MWCNT and Sb2Te3 was optimized to produce a high‐power density (~1.1 mW/cm2), and the optimal amount of FA to the tuned MWCNT:Sb2Te3 ratio resulted in a significantly sustained time (~68.55 seconds, 2698% enhancement compared to without FA). The pre‐decomposed carbon oxides and carbonate from the FA chemical reaction considerably delay self‐propagating reaction and promoted the evaporation of the Te species in Sb2Te3 and its oxidation to Sb2O3 and Sb2O5, which could produce additional energy generation (~0.29 mJ/cm2). A theoretical analysis elucidated the individual contributions of the Seebeck and chemical energy, and rational strategies to enhance the TWs. This work can pave the way for the development of advanced TW devices that satisfy the demands for both high energy density as well as long‐term power generation. [ABSTRACT FROM AUTHOR]

Summary: The use of metal electrocatalysts (Cu, Au, and Ag) is the mainstream in primary CO2 reduction systems, but their large overpotential induces a decrease in energy conversion efficiency. Recently, it has been discovered that carbon‐supported Pt can make a game change to reduce CO2 to CH4 electrocatalytically without overpotential; however, its faradaic efficiency remains only 12.3% thus far. One approach is to investigate the role of carbon supports for improving the efficiency. In this study, improved CO2 reduction was carried out by employing a Pt‐black electrocatalyst without a carbon support in a polymer electrolyte membrane electrolyzer cell. When supplying CO2 diluted by Ar gas at CO2 concentrations of 4‐7 vol.%, the efficient CH4 generation was observed. The reason behind the improved production of CH4 occurs by a Langmuir‐Hinshelwood mechanism associated with adsorbed CO (COads) and H (Hads) on the Pt electrocatalyst. Moreover, a high‐density COads environment (surface) can be created at the Pt‐black catalyst, achieving CH4 generation with a faradaic efficiency of 23.2% at 0.18 V vs RHE. Therefore, this study succeeded in improving the faradaic efficiency of CH4 production from CO2 reduction without overpotential using a Pt‐black electrocatalyst. [ABSTRACT FROM AUTHOR]

Summary: This paper reports the thermodynamic efficiency analysis of the SnO2/SnO redox cycle conducted using the HSC Chemistry software. A theoretical process model is developed and used, including reduction and oxidation cells, heaters, separators, and an ideal CO/O2 fuel cell. The thermodynamic calculations are performed by varying the reduction temperature (Tred) from 1500 to 2000 K, assuming a steady gas‐to‐gas heat recovery effectiveness (εgg) equal to 0.5, and oxidation temperature (Toxd) equal to 900 K. The obtained results indicate that as Tred increases from 1500 to 2000 K, the requirement of ṅinert reduces from 17 000 to 12 mol/s, respectively. The total thermal energy demand of the cycle is significantly affected by the energy needed to heat the inert/O2 gas mixture (from Toxd to separator‐1 temperature) and inert sweep gas (from separator‐1 temperature to Tred). A considerable reduction in Q̇TC (by 171 500.2 kW) and Q̇solar (by 189 259.6 kW) is noted due to the surge in Tred from 1500 to 2000 K. The SnO2/SnO CDS redox cycle attains the solar‐to‐fuel energy conversion efficiency is 16.7% at Tred of 2000 K. [ABSTRACT FROM AUTHOR]

Locked segments are widely present in the slip surface of large rock slopes and seismogenic faults of rock underground engineering. Each cracking occasion of the locked segment results in a seismic event. Accurate determination of the seismic source parameters of a locked-segment cracking event is crucial for the reliable evaluation of rock-mass stability associated with slopes and underground openings. The theoretical framework for calculating seismic source parameters in previous studies is mostly based on the stick-slip model, which is not applicable to describing the locked segment's damage process, and research on seismic source parameter estimation of a locked-segment cracking event is insufficient. Hence, based on the principle of energy conversion and distribution during the locked segment's damage process, we proposed an equation for the radiated seismic energy of a locked-segment cracking event. Using this equation, we established a mechanical relationship between the earthquake magnitude and the stress drop or shear strain increment (or maximum coseismic displacement) of a locked-segment cracking event. Typical case studies of rock slope and rock underground engineering showed that the proposed calculation method of seismic source parameters was reliable. In addition, this paper discusses the controversy surrounding the relationship between earthquake magnitude and stress drop. Relevant results lay a firm physical foundation to accurately calculate the seismic source parameters of a locked-segment cracking event and obtain detailed insights into the generation mechanism of the locked-segment cracking event. [ABSTRACT FROM AUTHOR]

The floating photovoltaic (FPV) system is a revolutionary power production technology that has gotten a lot of interest because of its many benefits. Aside from generating electricity, the technology can also prevent the evaporation of water. The electrical and mechanical structures of FPV power stations must be studied to develop them. Much research on FPV technologies has already been undertaken, and these systems have been evaluated from many perspectives. Many problems, including environmental degradation and electricity generation, fertile soils, and water management, are currently limiting societal growth. Floating photovoltaic (PV) devices save a great of land and water resources and have a greater energy conversion efficiency than standard ground power systems. A performance investigation of photovoltaic (PV) installations set on a moving platform is carried out. The paper presents and discusses various design alternatives for boosting the profitability and efficiency of floating photovoltaic (FPV) systems. Especially, FPV systems that take advantage of increasing capabilities like monitoring, conditioning, and attention were included. Although researchers have agreed on the benefits of floating systems, there has been little in-depth research on the parameters of floating photovoltaic systems. The results of this research tests were performed, and these reveal that the beneficial monitoring and conditioning impacts result in a significant gain in performance. The effects of using flat reflections on improvements are also investigated. As a result, this research examines the evolution of photovoltaic systems, then investigates the power generation capacity of floating photovoltaic systems, and then examines the benefits and possibilities of floating PV systems in depth. The concept of developing an integrated air storage system using a floating building on waters is discussed. [ABSTRACT FROM AUTHOR]

Summary: The design of CuS/SiO2@n‐octadecane nanocapsules with high sensitivity to light and heat is being conducive to photothermal conversion and efficient utilization of solar energy. In this work, CuS was deposited on the surface of the SiO2 shell by the chemical bath deposition method. Through the characterization of microstructure and chemical composition, the granular CuS crystal was uniformly coated on the SiO2 shell. The synthesized nanocapsules are spherical and have a perfect core‐shell structure. The quantity, distribution, and size of CuS deposited on the shell can be adjusted by regulating the synthesis parameters. The prepared CuS/SiO2@n‐octadecane nanocapsules have a melting temperature of 26.85°C and melting enthalpy of 65.0 J/g at the optimum preparation condition (10 mmol/L cetyltrimethylammonium bromide, 70°C, 0.02 mol/L Cu2+) and have excellent durability. The light absorption performance of CuS/SiO2 nanocapsules in the Vis‐NIR was significantly enhanced, photothermal conversion efficiency reached 52.7%. In addition, the CuS/SiO2 nanocapsules also showed good photocatalytic performance, and the degradation degree of methyl orange reached 71% within 3 hours. These results show that the designed photo‐driven nanocapsules have excellent performance and great potential in solar energy utilization and intelligent fabric. Highlights: We have creatively synthesized PCM nanocapsules with CuS/SiO2 shells.The melting enthalpy and melting temperature are 65.0 J/g and 26.85°C, respectively.The activity of the SiO2 shell was increased by amino coupling agent modification.CuS has increased 4‐5 times of photothermal conversion efficiency in Vis‐NIR. [ABSTRACT FROM AUTHOR]

Distribution network line loss calculation refers to the calculation of the electrical energy loss, which is generated by all components in a distribution network system in a given period of time. Distribution network, as the end of the power network, is directly connected with users; there are many equipment on the network; the system has impedance, electric energy in the process of conversion, transmission and distribution with a lot of loss, so the calculation of distribution network line loss has very important economic significance. In addition, with the development of power network construction, the rationality of distribution network topology design and the comparison of practical effects of various measures need the guidance of line loss calculation. Line loss and line loss rate is one of the main criteria to reflect the operation of distribution system. Reducing line loss of distribution system is very important for the effective use of power and economic operation of distribution system. In order to better find the effective reduction method and lay the foundation for the scientific establishment of linear contraction targets. This study uses a line loss calculation method based on BP neural network. The method uses the super matching property of the network to map the complex nonlinear relationship between the line loss and the characteristic variables and stores the evolution of the line loss changes with the changes of the structural and operational variables of the distribution line. On the basis of analyzing the theoretical methods, management methods, and various loss reduction measures of power loss calculation, this study also analyzes the status quo and existing problems of line loss analysis and calculation and collects data from line loss calculation and theoretical line loss calculation methods. This study discusses in detail the method and idea of the application of the improved neural network in the estimation of distribution network line loss, and it is used to predict the line loss in a certain area, and the prediction result is good. [ABSTRACT FROM AUTHOR]

During the fruit ripening period, the orchard temperature difference between day and night has a substantial impact on the fruit quality, and it is not easy to be controlled like that of in greenhouse, this paper designed the smart orchard Internet of Things (IoT), through the fuzzy PID (Proportion-Integration-Differentiation) algorithm to control the water spraying to adjust the temperature difference Δ T between day and night in the orchard, intelligently influenced the orchard energy conversion process, and promoted the fruit sugar accumulation. Experiments show that the maximum Δ T can reach 20°C, the intelligent energy regulation based on the IoT has a good effect, and a scheme to intervene the microclimate in farmland (quite different from the greenhouse environment) is provided. [ABSTRACT FROM AUTHOR]

To prolong the lifetime of energy-constrained cooperative networks, radio frequency energy harvesting (RFEH) technology can effectively solve the energy constraints of nodes batteries, and we consider the maximum ratio combining (MRC) method at the destination node to improve the reliability of the link transmission. Thus, we propose the power splitting-based double-relay cooperative transmission (PSDRCT) protocol with RFEH in the decode-and-forward (DF) mode in this study. According to the transmission process of the proposed protocol, the analytical expressions of outage probability, throughput, and energy efficiency are obtained. Numerical simulation results demonstrate that the location of the relay nodes, power allocation ratio, energy conversion efficiency, and transmission power are the key factors affecting the performance of the protocol. In addition, the proposed protocol has lower outage probability than the time switching-based double-relay cooperative transmission (TSDRCT) protocol under the same power allocation ratio and energy conversion efficiency. [ABSTRACT FROM AUTHOR]

Summary: Solid oxide fuel cells (SOFCs) are promising electrochemical energy conversion devices that convert fuels into electricity efficiently and cleanly. Modeling mass transport in SOFCs is essential for understanding and designing better fuel cells. In the last decades, the modeling of SOFCs has made significant progress, raising several issues to be addressed. One major issue is how to couple the electronic conduction in electrolyte and the other transport processes in a thermodynamically consistent way. Herein, we developed an analytical model to address this issue. The model is verified by the literature data and can predict the low open‐circuit voltage that most present models do not describe. By combining Fick's law for gas transport and the Butter‐Volmer equation for electrode reactions, the ionic and electronic current through the cell, the overpotentials (oxygen partial pressures) across electrode/electrolyte interfaces, and voltage‐current performance of SOFCs can be calculated and are validated by experimental data of SOFCs with ceria‐based electrolyte. The influence of the anode support parameters, including porosity, tortuosity, pore diameter, and support thickness, is studied, guiding SOFCs' microstructure design. The model can also serve as a sub‐model for stack‐ and system‐scale design of SOFCs. [ABSTRACT FROM AUTHOR]

Summary: Today, the application of nanoparticles with controlled morphologies in solar energy conversion and storage systems is highlighted. This study focused on the assessment of Fe2O3 water‐based nanofluids in volumetric solar absorbers and compared the performance of three shapes (blade, spherical, and octahedral), and three concentrations of nanoparticles (0.005, 0.01, and 0.02 vol%). First, a set of homogeneous nanofluids were prepared using a probe ultrasonic apparatus and by adding an anionic surfactant. In addition to long‐time stability and narrow particles size distribution, obtained nanofluids presented a considerable light absorption capability in the visible region. It was seen that the light absorption spectrum was broadened with increasing the nanofluid concentration. Moreover, for each concentration, the blade nanoparticles improved the extinction coefficient and the solar‐weighted absorption fraction relatively higher than the other shapes. For example, at a concentration of 0.02 vol% and penetration distance of 1 cm, the blade‐nanofluid absorbed 96.2% of incident solar energy, which was higher than the spherical nanofluid with 93.5% and octahedral nanofluid with 87.2%. The results of thermal tests conducted in a set of bath direct solar collectors showed that the highest solar–thermal conversion efficiency after 1 hour of light exposure was related to 0.02% blade‐nanofluid (82%). In these conditions, the growth of bulk temperature was observed 2.31 times higher than pure water. [ABSTRACT FROM AUTHOR]

Summary: Recently, we have witnessed a remarkable proliferation of wearables in various smart applications. These applications include smart healthcare, smart military, smart infotainment, and smart industries, to name a few. However, wearables suffer from significant energy limitations. To cope with this challenging issue, energy harvesting can be a viable solution. In this paper, various ambient sources like heat, vibration, radio waves, and solar energy are compared and critically analyzed based on size, voltage, frequency, power density, and power. Critical analysis of vibrational, solar, heat, radiofrequency, and hybrid show convincing output results, but a hybrid solar wearable energy harvester (SWEH) and thermoelectric wearable energy harvester (TWEH) give a maximum output power of 501 mW. However, piezoelectric clothes fabrication is growing and coming out to be a good competitor because of flexibility and comfort. Work has been done on the hybridization of wearable clothes to generate maximum power and is good enough for wearable applications. On the other side, solar individually is enough to power wearable devices but for a specific time. In the radiofrequency still, research is required because of very low power generation or a flexible array can be integrated into a dress or certain other technique maybe adapted for flexible yet more power generation capability. Overall sizes of the reported wearable energy harvesters are in the millimeter to centimeter scale, with resonant frequencies in the range of 1 to 1400 Hz, while rectenna wearable energy harvester (RWEH) exceeds the limit and is reported in the range of 1.8 to 3.2 GHz. A maximum energy conversion for a piezoelectric wearable energy harvester can potentially reach up to 29.7 μW/cm3 and 14.28 μW/cm2. The power produced by the reported hybrid energy harvesters (HEHs) is in the range of 0.00012 to 501 mW. Due to the combined solar‐thermoelectric energy conversion in HEHs, these systems are capable of producing the highest power densities. [ABSTRACT FROM AUTHOR]

Summary: In large thermal power facilities, thermal machines mainly fitted with steam turbines are used in thermodynamic process of converting thermal energy into mechanical work. In order to improve the efficiency of heat energy conversion into mechanical work, the increase of vacuum level in the condenser of a steam turbine was analyzed using the machine learning method. The vacuum in the steam turbine condenser increases after replacing the labyrinth gaskets with honeycomb ones, resealing the vacuum system and increasing the amount of cooling water through the condenser. The latter is controlled by algorithm, which is integrated into the steam turbine distribution control system. As a result of the increased vacuum in the steam turbine condenser, the enthalpy difference of the steam turbine low‐pressure cylinder increases, and the steam turbine performs more mechanical work resulting in higher conversion efficiency. The drawback of the increased vacuum in the turbine condenser is that the flow of cooling water through the steam turbine condenser increases as well as heat dissipation from the condenser into the environment to be replaced by regenerative condensate heating. The results of the analysis show that the overall balance of the vacuum increase in the steam turbine condenser is positive, the steam turbine generates more power, and consequently the process efficiency increases by as much as 2.48 %. [ABSTRACT FROM AUTHOR]

Summary: The integration analysis, modeling, and improvement of the multiple thermoelectric cooling components are significant for promoting thermoelectric cooling technology. Based on the heat current method, this paper studied a single thermoelectric cooling component and constructed its equivalent circuit model by integrating the coupled thermoelectric conduction and conversion processes with the convective heat transfer processes of both the hot side and cold side. The equivalent circuit model is used to build system‐level energy transfer and conversion models of the thermoelectric refrigeration systems with parallel‐flow, counter‐flow, and cross‐flow layouts. On this basis, the corresponding calculation process is provided by combining with the Gauss‐Seidel Algorithm based on MATLAB software. The simulation results show that the cooling capacity and coefficient of performance under the counter‐flow layout are the maximum, and the average end temperature difference is the minimum when the working current is uniform. Besides, the reasonable non‐uniform working current allocation can effectively improve the cooling capacity of the thermoelectric refrigeration system by 6.6%, 32.3%, and 1.7%, respectively. Finally, experimental results verify that the proposed heat current model of the thermoelectric cooling unit is appropriate and feasible for modeling and improving the performance by counter‐flow layout and non‐uniform working current allocation. [ABSTRACT FROM AUTHOR]

Summary: Structural, elastic, electronic, and optical properties of Cs‐based halide perovskite compounds CsHgX3 (X═F and Cl) are computed in the framework of density functional theory (DFT). The obtained optimized lattice parameters are found to agree with available experimental and other theoretical data. Elastic parameters, such as anisotropic factor, bulk modulus, elastic constants, Pugh's ratio, and Poisson's ratio, are predicted. It is observed from the elastic properties measurements that these compounds are ductile, anisotropic, and mechanically stable. Band structures and density of states (DOS) are performed for the computation of electronic properties and it is found that the calculated bandgap of CsHgF3 is of an indirect and semiconductive nature, while CsHgCl3 reveals metallic nature. For more clarification of electronic properties, the DOS presents the different contributions of valence states to valence and conduction bands. Optical properties, such as real and imaginary parts of dielectric functions, reflectivity, extinction coefficients, absorption coefficients, optical conductivity, and refractive indices, are also calculated in the energy range 0 to 30 eV. From the optical properties, it is found that these materials possess high absorption and refractive index, due to which it can be deemed as a suitable candidate for optical lenses and optical coating materials. [ABSTRACT FROM AUTHOR]