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The construction of anti-disaster backbone grid is of great significance to enhance the power supply capacity of power system under extreme natural disasters. Comprehensively considering economy and reliability, a planning method for anti-disaster backbone grid was proposed. The economy and reliability of the planning scheme were expressed as the strengthened cost and the benefit from loss reduction in life cycle. The objective function was to maximize the unit benefit from loss reduction of the original grid caused by the unit strengthened cost of backbone grid. Taking the network connectivity and safe operation of power system into account, a planning model for anti-disaster backbone grid was established. The model was solved by the improved crisscross optimization (ICSO) algorithm to find the optimal planning scheme. Finally, the effectiveness of the proposed method was verified by the simulation analysis of the IEEE 30-bus system.

The current study focuses on spray cooling applied to the heat exchange components of a cooling tower. An optimization of such processes is attempted by assessing different spray flow rates and droplet sizes. For simplicity, the heat exchanger of the cooling tower is modeled as a horizontal round tube and a cooling tower spray cooling model is developed accordingly using a computational fluid dynamics (CFD) software. The study examines the influence of varying spray flow rates and droplet sizes on the heat flow intensity between the liquid layer on the surface of the cylindrical tube and the surrounding air, taking into account the number of nozzles. It is observed that on increasing the spray flow strength, the heat flow intensity and extent of the liquid film in the system are enhanced accordingly. Moreover, the magnitude of droplet size significantly impacts heat transfer. A larger droplet size decreases evaporation in the air and enhances the deposition of droplets on the round tube. This facilitates the creation of the liquid film and enhances the passage of heat between the liquid film and air. Increasing the number of nozzles, while maintaining a constant spray flow rate, results in a decrease in the flow rate of each individual nozzle. This decrease is not favorable in terms of heat transfer. Graphic Abstract [ABSTRACT FROM AUTHOR]

Using the high-quality Crown Pear as the subject of experimental research, an analysis of the changes in the quality of Crown Pears during a storage period is conducted to provide a theoretical basis for the development of the pear cold storage industry. The study utilizes a handheld digital refractometer, texture analyzer, colorimeter, T-type thermocouple, and electronic balance to explore six aspects of Crown Pears: soluble solids content, hardness, color difference, freezing point, drying loss, and taste. The results reveal the following changes in pear quality during different storage periods within one cycle: the content of soluble solids in Crown Pears initially increases and then decreases during the storage period; hardness decreases with increasing storage time; the external appearance of pears gradually darkens; and drying loss increases with storage time. During the cold storage process of Crown Pears, the optimal temperature setting for the cold storage should be maintained at -1°C to 0.5°C. The flavor of Crown Pears is not optimal during the early stage of storage. The storage time for Crown Pears should be within four months.

In order to gain a deeper knowledge of the heat and mass transfer processes in the case of starchy fruits and vegetables during microwave drying, we have conducted an experimental study based on a developed microwave apparatus for drying potato. The changes in the temperature, drying rate, moisture content, thermal parameters, moisture state and distribution of the potatoes samples during the microwave drying process were obtained. The results show that, according to the temperature changes of the samples dried at different microwave powers (600 W, 800 W, 1000 W), the microwave drying process can be divided into three stages: heating stage, constant temperature stage, and cooling stage. The moisture content reduction of the samples in the constant temperature stage accounted for more than 90% of the total reduction. Meanwhile, as the microwave drying process goes by, the thermal conductivity and thermal diffusivity of the samples both decrease first and then increase, while the volumetric heat capacity presents an opposite trend. Moreover, the range and amplitude of transverse relaxation time of the samples reduce over the drying time, which confirms the existence of massive, outward moisture-migration in the dried samples. The loss of the weakly bound water in the moisture-migration, which is closely related to the starch, has a significant effect on the heat and mass transfer in the dried samples. [ABSTRACT FROM AUTHOR]