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In this study, a new lattice Boltzmann scheme is developed for the two-phase CuO–H2O nanomagnetic fluid (ferrofluid) under a non-uniform variable magnetic field. It introduces the second-order external force term including both MHD (magnetohydrodynamic) and FHD (ferrohydrodynamic) into the lattice Boltzmann equation. The square cavity and a heat source inside the circular cavity with natural convections of nanofluid are investigated, respectively. The effects of Rayleigh number (Ra), the volume fraction of nanoparticles (φ), Hartmann number (Ha) generated by MHD, and magnetic number (MnF) generated by FHD on the nanofluid flow and heat transfer properties, as well as the total entropy generation (Stot) have been examined. The two-phase lattice Boltzmann model has demonstrated that it is more accurate in predicting the heat transfer of nanofluid than the single-phase model. Consequently, the results calculated by the single-phase and the two-phase methods show the opposite trends. It indicates that nanoparticles could enhance heat transfer with maximum values of 1.78% or deteriorate heat transfer with maximum values of 14.84%. The results of the circular cavity show that Ha could diminish the flow intensity, whereas MnF could enhance it. The average Nusselt number (Nuave) on the heat source decreases with the augments of Ha and MnF but increases with Ra. An optimal volume fraction φ = 1% for heat transfer is obtained except for Ra = 104. Stot achieves the maximum value at Ha = 40 when Ra = 105. It increases with a rise of Ra but reduces with an increment of φ. [ABSTRACT FROM AUTHOR]

Summary: In this paper, the mathematical models of each part of the direct‐drive variable speed pumped storage unit are established, including the model of the pump turbine and its regulating system, the model of direct‐drive motor, and its excitation control system. Then we introduce two control methods of variable speed pumped storage unit, namely power priority control method, and speed priority control method. And then, the influence of the value of the internal parameters of the unit on the control characteristics of the unit is analyzed, and the control system of the unit is designed according to the value of the internal parameters of the unit, and the control parameters with the optimal control effect are obtained. Finally, the obtained optimal control parameters are verified using simulation software. [ABSTRACT FROM AUTHOR]

The article presents authors of the article "Comparative Evaluation of Two Dose Optimization Methods" reply addressing the significant difference between optimization algorithm and optimization model. The authors notes on the objective function used to drive solutions to the cervix brachytherapy optimization problems. The authors also discusses the clinical study on cervix brachytherapy.