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This paper developed two robust data-driven models, namely gene expression programming (GEP) and multivariate adaptive regression splines (MARS), for the estimation of the slump of concrete (SL). The main feature of the proposed data-driven methods is to provide explicit mathematical equations for estimating SL. The experimental data set contains five input variables, including the water-cement ratio (W/C), water (W), cement (C), river sand (Sa), and Bida Natural Gravel (BNG) used for the estimation of SL. Three common statistical indices, such as the correlation coefficient (R), root mean square error (RMSE), and mean absolute error (MAE), were used to evaluate the accuracy of the derived equations. The statistical indices revealed that the GEP formula (R=0.976, RMSE=19.143, and MAE=15.113) was more accurate than the MARS equation (R=0.962, RMSE=23.748, and MAE=16.795). However, the application of MARS, due to its simple regression equation for estimating SL, is more convenient for practical purposes than the complex formulation of GEP. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the melting characteristics of a phase change material (PCM) in a latent heat storage system equipped with hemispherical and quarter-spherical fins. A vertical triple-pipe heat exchanger is used as the PCM-based heat storage unit to improve the melting performance compared with a double-pipe system. Furthermore, the fins are arranged in inline and staggered configurations to improve heat transfer performance. For the quarter-spherical fins, both upward and downward directions are examined. The results of the system equipped with novel fins are compared with those without fins. Moreover, a fin is added to the heat exchanger's base to compensate for the natural convection effect at the bottom of the heat exchanger. Considering similar fin volumes, the results show that the system equipped with four hemispherical fins on the side walls and an added fin on the bottom wall has the best performance compared with the other cases with hemispherical fins. The staggered arrangement of the fins results in a higher heat transfer rate. The downward quarter-spherical fins with a staggered configuration show the highest performance among all the studied cases. Compared with the case without fins, the heat storage rate improves by almost 78% (from 35.6 to 63.5 W), reducing the melting time by 45%. [ABSTRACT FROM AUTHOR]

In this research work, the high-yielding and simple synthesis of 5-substituted 1H-tetrazoles derivatives through the one-pot three-component reaction of aldehydes, hydroxylamine hydrochloride and sodium azide catalyzed by MNPs-Picolylamine-Cu(OAc)2 nanocomposite in water under microwave irradiation has been reported. The MNPs-Picolylamine-Cu(OAc)2 nanocomposite is successfully fabricated through the immobilization of copper (II) acetate stabilized on magnetic Fe3O4 nanoparticles modified with Picolylamine [MNPs-Picolylamine-Cu(OAc)2] and then is well analyzed by various techniques such as FT-IR, XRD, TGA, SEM, TEM, EDS, VSM and ICP-OES. At the end of the reaction, the MNPs-Picolylamine-Cu(OAc)2 catalyst can be easily recycled and reused and the products obtained had high efficiency and purity. [ABSTRACT FROM AUTHOR]

Environmental concerns and higher energy demand require more energy. Solar and wind are renewable energies. One of the most important and available renewable energy sources is the use of wind and solar sources. This study examines energy generation and battery storage systems for lowering peak load and smoothing a residential substation's load curve. This study aims to present a useful and effective mechanism for improving the design of a hybrid system using solar panels and wind turbines to provide the common peak load and as much actual load demand as possible at the desired location. The proposed method provides the optimal solution after obtaining light radiation, wind speed, and load demand. Training and learning-based algorithms optimize. This study focuses on reducing lifetime costs. Prices and equipment are accurate, and power plant costs include initial and ongoing costs. PSO optimizes Karachi's anemometer and radiation data. The results showed that the network's summer, fall, and winter peak outputs are 12368 kW, 14865 kW, and 77 147 kW; the systems are 68.31 kW, 29.38 kW, and 2337 kW. Using the seasonal average rather than the annual average improves the system's dependability and provides a more accurate response to the desired peak load. Wind and solar hybrid systems connected to the grid can reduce the grid's peak load and total cost over time. [ABSTRACT FROM AUTHOR]

The vibration and stability of spinning viscoelastic Y-shaped bifurcated nanotubes conveying fluid in complex environments by considering additional concentrated masses and springs are studied based on the nonlocal strain gradient theory (NSGT). A detailed investigation is also performed to clarify the effect of influential parameters such as Knudsen number, magnetic nanoflow, scale parameter ratio, spin speed, fluid velocity, downstream bifurcation angle, viscoelastic coefficient, attached springs, localized masses, boundary conditions, and magneto-hygro-thermal environments on the system dynamics. The size-dependent dynamical equations of the system are derived utilizing Hamilton's principle. The Galerkin discretization scheme is adopted, and the eigenvalue problem is numerically solved. Campbell diagrams, forward and backward frequencies, divergence and flutter instability maps are acquired. Besides, the static instability threshold of the system is determined analytically. Results revealed that although the magnetic nanoflow has a decreasing effect on system vibrational frequencies, it delays the occurrence of the dynamical instability and prevents the buckling phenomenon. It is demonstrated that by considering simultaneous stiffness-softening effects induced by nonlocality and hygro-thermal environments, the flutter instability could occur instead of divergence condition in the system stability evolution. The present modeling and results could be applied as a benchmark for the performance improvement of innovative bi-gyroscopic nanofluidic devices. [ABSTRACT FROM AUTHOR]

The utilization of solar and wind energy as alternatives to fossil fuels is gaining increasing significance in the quest for sustainable energy solutions. Hybrid systems, comprising multiple power generation units driven by diverse energy sources, offer enhanced reliability compared to single-source systems. Among these, photovoltaicwind turbine hybrids have emerged as a promising configuration, capable of meeting extensive and dynamic energy demands. In certain hybrid systems, domestic batteries are employed to counter daily fluctuations, facilitating the conversion and storage of energy for grid-independent applications. The present study conducts a technoeconomic analysis of such a hybrid system, employing HOMER software for power supply simulations. Results indicate that the optimal configuration encompasses 10 kW photovoltaic cells, a 10 kW wind turbine, a 4 kW water electrolysis device, a 10 kW converter, a 1 kW fuel cell, and a 1 kg storage tank. [ABSTRACT FROM AUTHOR]

Fuel cells serve as environmentally friendly alternatives to fossil fuels by providing clean energy. Integrating a fuel cell with an energy storage system, such as a battery, results in cost savings and performance improvements. The battery functions as an energy storage source, enabling the regulation and maintenance of fuel cell power at acceptable levels. Introducing an innovative and optimal power management method for hybrid electric energy supply systems can significantly contribute to the advancement of renewable resources by reducing costs, enhancing energy efficiency, increasing system reliability, and improving fuel cell lifespan. In this study, a membrane exchange fuel cell model, combined with a battery, is presented using MATLAB. The results demonstrate an increase in fuel cell life, energy efficiency, and output power quality. The state of charge (SOC) of the battery fluctuates between 52% and 34%, while the output power of the proton exchange membrane fuel cell (PEMFC) ranges between 30 and 20 watts. It is worth noting that, during the 1,200-second power supply process using the proposed strategy, only six PEMFC working points have changed. [ABSTRACT FROM AUTHOR]

The journal Energies has retracted an article titled "Investigation and Evaluation of the Hybrid System of Energy Storage for Renewable Energies" due to concerns of overlap with a previously published manuscript in another language. An investigation conducted by the Editorial Office, members of the Editorial Board, and the Editor-in-Chief confirmed significant overlap, leading to the retraction of the article. Some authors agree with the retraction, while others disagree, and the remaining authors did not provide a comment on the decision. [Extracted from the article]

Forced and free dynamic responses of nanobeams resting on a three-parameter foundation subjected to a moving force in magneto-hygro-thermal conditions are investigated based on the nonlocal strain gradient theory. Also, a detailed parametric study is conducted to identify the impact of slender ratio, axial and distributed tangential loads on the vibration characteristics and dynamic phenomena of the small-scale system. Comparative studies with existing results in the literature are performed to ensure the accuracy of the presented model and solution approach. Analytical and numerical methods are implemented to detect the effects of foundation coefficients, environmental conditions, geometrical and scale parameters on the dynamic amplification factor, critical moving force velocity, cancellation, and maximum free response mechanisms of the system. The outcomes revealed that the critical moving force velocity is enhanced by ascending the slender ratio, elastic, and shear moduli of the foundation. It is found that when the damping factor is considered for the foundation, it is feasible to prevent the occurrence of the cancellation phenomenon. Also, it is concluded that by fine-tuning scale parameters and environmental conditions, unwanted vibration of the system can be suppressed. The attained results of this study can be helpful in the vibration control of nanoscale actuators, switches, and resonators. [ABSTRACT FROM AUTHOR]

Thispaper presents an optimal control strategy that can guideany initial random configuration of nanoparticles to a final structureof desired geometry, in minimum time. It employs a multiresolutionview of the dynamically evolving configurations of nanoparticles,which are described through the adaptive finite state projection (AFSP)approach introduced in part 3 of this series. External charges, attractingor repelling the nanoparticles, are the controls, whose location andintensity are determined by the optimality conditions of the optimalcontrol strategy. To ensure analytic consistency of the parametricsensitivities, during the computation of the optimal controls, andthus guarantee the optimality of the resulting control policy, a prioridetermination of enlarged constant projection spaces is shown to beessential. A case study illustrates the use of the proposed optimalcontrol strategy and illuminates several of its features, such assuperiority over a static optimal solution; evasion of kinetic traps;and effective handling of combinatorial complications arising forsystems with large-size domains and many particles. [ABSTRACT FROM AUTHOR]

Hydrogen production from electrochemical water dissociation has been considered as a facile and promising approach to address energy related crisis in the world. In this regard, development of high performance, stable, and cost-effective catalysts for full water splitting is highly demanded. In this work a high performance electrocatalyst based on commercially available Tin oxide nanoparticles mixed with carbon nanotubes (CNT) is presented for electrocatalytic water splitting. The catalyst prepared through facile dropped casting method and obtained a high electrocatalytic activity for full water splitting. One of the key important parameters in water splitting is producing hydrogen/oxygen at high rate under long term stability. This is problematic because it would result in catalyst degradation and performance fallen. However, herein, the prepared electrocatalyst demonstrated a high stability of more than 10 h operation under a high applied current density of 100 mA.cm−2 for hydrogen evolution reaction. For the both hydrogen and oxygen, the prepared catalyst (SnO 2 /CNT coated on carbon paper) delivered the current density of 10 mA.cm−2 at a low overpotentials of 150 mV and 250 mV, respectively. Our observations validate the excellent capability in significantly modifying the catalytic activity of transition metal compound catalysts with carbon nanostructures. [Display omitted] • A synergetic effect of CNT and SnO 2 combination on the electrocatalytic performance was observed. • A lower overpotentials required to reach high current densities, along with high stability at high current. • CNT hybridization with SnO 2 influenced the Volmer step of HER. Also, the adsorption of oxygen and hydrogen affected. • The open structure accelerated the gas detachments during OER or HER, influencing the performance of the system. [ABSTRACT FROM AUTHOR]