To enhance the accuracy and stability of photovoltaic power forecasting under typical weather conditions, this paper proposes a forecasting model that integrates an improved spectral clustering method optimized by the NSGAⅡ multi-objective algorithm with a BiLSTM network enhanced by a multi-head attention mechanism （MHA）. Firstly, outlier detection and preprocessing are performed on meteorological and historical PV data, and key influencing features are identified. Then, the construction of the degree matrix in spectral clustering is improved using dynamic time warping （DTW）, and NSGAⅡ is employed to optimize the sparsity of the similarity matrix and the Gaussian kernel parameter, yielding an optimal clustering model that categorizes weather into sunny, cloudy, and rainy types. Finally, optimal NSGAⅡ-BiLSTM-MHA models are established for each weather type and compared with four baseline models. Results show that, under three weather conditions, the proposed model achieves 50.74%-62.95% lower RMSE and 55.85%-60.09% lower SDEX than that of SVR, while improving the R² by 8.99%-17.07%.

Conventional infrared reflective layers often struggle with thermal instability at high temperatures or insufficient infrared reflectivity, limiting their practical applications. In this study, we employed a microalloying approach to enhance film performance by incorporating tantalum （Ta） into silver （Ag） films via magnetron sputtering. The reflective spectra, crystal structure, and surface morphology of the films were systematically analyzed. The results indicate that Ta doping effectively inhibites the preferred growth of the Ag（111） crystal plane. Furthermore, high-vacuum thermal stability tests at 600 ℃ confirm that the AgTa infrared reflective coatings retain excellent optical and structural stability, even under elevated temperatures.

In this paper, a two-dimensional model of horizontal pipeline with built-in electric heat tracing device is established to simulate the position, shape and temperature field distribution of solid-liquid interface of mixed molten salt nanofluid during the melting process, and to analyze the influence of different Ste and the size of the electric heat tracing device on the whole molten salt melting process. The results indicate that, as the heating duration increases, the distance between the electric heating system and the phase interface increases, and the transfer of heat to the molten salt in the solid phase gradually slows down due to the increase in thermal resistance. and the molten salt nanofluid is completely melted when the heating time lasts for 3082 s. The temperature of the solid-liquid interface is reduced by the influence of the thermal resistance of the electric trace heating device. When Ste increases from 0.392 to 0.706 and 1.021, the complete melting time of the molten salt nanofluid is reduced by 66% and 81%, respectively; compared with the 5 mm diameter electric trace heating device, the melting efficiency of the molten salt of the electric trace heating device with diameters of 10 mm and 20 mm is increased by 68% and 82%, and the time of complete melting of the molten salt is 1100 s and 623 s, respectively.

With the development of concentrated solar power generation technology and the need for heat recovery from industrial exhaust gases and high-temperature flue gases, high-temperature molten salt power generation technology plays an increasingly important role. In some cases, due to the process needs, it is necessary to mix the low-temperature molten salt with the high-temperature molten salt to reach the desired temperature. In this paper, Ansys Fluent software was used to study the flow, heat transfer and thermodynamic characteristics of the mixing process in the high temperature molten salt mixing tank, and the influence of different structures on the mixing performance was also analyzed. According to the results, it is obtained that the air inside the tank is heated by the molten salt during the salt charging process of the mixing tank, resulting in a certain amount of heat loss, which makes the actual mixing time longer than the theoretical calculation time. In the salt charging process, the baffle structure prevents part of the heat exchange between the molten salt and the air, which reduces the heat loss, and the baffle is more conducive to shorten the mixing time without opening holes. Besides, for elbow counter-current inlet type, the cold and hot molten salt fully contact when they were out from the inlet, which show better mixing result than the manifold inlet structure.