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In order to reduce the adverse effects of structural errors on a novel 5-degrees of freedom (DOF) parallel kinematic mechanism (PKM) with subclosed loops, studies on the elastodynamic modeling and structural error compensation are conducted in this paper. First, considering that introduction of subclosed loops significantly increased the complexity and difficulty of elastodynamic modeling, an equivalent unit modeling method for the branch chain with subclosed loop is proposed based on force analysis and deformation compatibility condition. Then, elastodynamic model of the whole 5-DOF PKM is established with the matrix structural analysis based method. Second, by defining a six-dimensional error (three translational errors and three rotational errors) for each node, structural error model of the PKM is constructed based on closed-loop vector method. To consider the coupling effects of static and dynamic structural errors, the dynamic structural errors derived by above elastodynamic model would be substituted into the structural error model along with given static structural errors. Finally, structural error compensation optimization model is established and structural errors are compensated by adjusting the driven parameters based on the improved particle swarm optimization (PSO) algorithm. Numerical simulations are conducted to verify the proposed elastodynamic modeling and structural error compensation methods. After compensation, the position errors along x, y, and z directions are respectively decreased by 68.036%, 81.409%, and 90.625%, and the angle errors around x and y directions are respectively decreased by 91.426% and 62.042%. [ABSTRACT FROM AUTHOR]

In this paper, a recuperator model is established to simulate the real working state of the recuperator in the micro turbine. The relative error between simulated and experimental data doesn't exceed 5%, which indicates that the model can better reflect the changing law of the recuperator performance. Therefore, the recuperator model proposed in this paper is reasonable and reliable. In addition, the simulation results indicate that heat transfer efficiency is not sensitive to the change of hot inlet temperature, however, it increases with the decrease of mass flow rate. On the other hand, the decrease of inlet mass flow leads to the relative pressure loss decreased on hot and cold sides.

In this study, for the selection of maximum material removal rate and minimum surface roughness (R a) in micro-grinding of aluminum alloy through multi-response optimization, two optimization approaches are proposed based on statistical analysis and genetic algorithm. The statistical analysis–based approach applies response surface methodology according to the analysis of variance to propose a mathematical model for R a . In addition, the individual desirability of material removal rate, R a , and the global desirability function are calculated, and the inverse analysis is conducted to locate input setting giving maximum desirability function. The genetic algorithm–based approach uses the improved multi-objective particle swarm optimization with the experimental data trained by support vector machine. To demonstrate that the material microstructure is a significant parameter for material removal rate and R a , the models with and without Taylor factor consideration are developed and compared. The optimized results achieved from both response surface methodology and improved multi-objective particle swarm optimization demonstrate that the consideration of Taylor factor can significantly improve the optimization process to achieve the maximum material removal rate and minimum R a . [ABSTRACT FROM AUTHOR]

Summary: To answer how surface corrosion affects the heat transfer performance of phase‐change immersion cooling solar cells, electrochemical etching was used for substrate surface treatment of simulated dense‐array solar cells in this paper. Morphology, roughness, and wettability of treated surfaces were characterized by scanning electron microscope, atomic force microscope, and spreading area, respectively. A self‐running cooling system was developed to investigate the effect of surface treatment on self‐running characteristics and heat transfer performance under different ethanol inlet temperatures and concentration ratios. The results show that the surface treated for 2 hours owns higher wettability because of the honeycomb‐like porous structure. Lower ethanol flowing velocity obtained under lower ethanol inlet temperature with treated samples. The maximum declined degree in the wall superheating of 21.1% and the maximum enhancement in the heat transfer coefficient of 33.3% are obtained for sample treated for 2 hours because of its higher wettability and porosity structure. The results show that electrochemical etching on substrate surface can improve the phase‐change immersion cooling performance of solar cells. [ABSTRACT FROM AUTHOR]

3,6-Carbazole precursors were used to prepare an octaphyrin. The conformation and electronic structure of the system could be modulated through trifluoroacetate (TFA) protonation and BF 2 complexation. The resulting nonaromatic macrocyclic complexes, 2-2TFA and 2-2BF 2 , displayed noteworthy photophysical properties. For instance, the diprotonated species 2-2TFA showed a strong panchromic absorption up to 800 nm, while the bis-BF 2 -chelated dipyrromethene (BODIPY)-like complex 2-2BF 2 exhibited an intense visible absorption feature (ε 535nm = 2.1 × 10 5 M -1 cm -1 ), as well as a relatively red-shifted emission at 640 nm characterized by a large Stokes shift. It was found that 2-2BF 2 could be used to construct a high-quality organic microlaser that functions under optical pumping. The present study highlights the potential utility of expanded porphyrins as possible laser dyes.