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Cryopreservation in the temperature range from −120 °C to −60 °C is an important way to achieve high-quality food storage. In this paper, an in-depth quantitative thermodynamic comparison of two-stage cascade cycle, Linde-Hampson cycle and reverse Brayton cycle was carried out in the temperature range from −120 °C to −60 °C. Aspen HYSYS was used to invoke advanced genetic algorithm in MATLAB to optimize the system parameters. The two-stage cascade system performs best at the evaporation temperatures above −80 °C, achieving a COP of 0.97 at −60 °C. The Linder-Hampson system performs best when the evaporation temperature is below −90 °C, achieving a COP of 0.35 at −120 °C. In order to further explore the impact of environmental change on the system performance, five typical cities in China were selected to analyze the seasonal performances of the three systems. The seasonal analysis demonstrated that Harbin has the highest latitude and its seasonal energy efficiency ratio is significantly higher than other cities, the performance of the two-stage cascade system fluctuates more obvious within 24-h. What's more, the Linder-Hampson system has the lowest annual investment cost and annual operating cost at the evaporation temperature lower than −90 °C, as well as the lowest emissions of CO 2 and SO 2. • Thermodynamic characteristics of different refrigeration systems are studied. • Two-stage cascade system performs best at evaporation temperatures above −80 °C. • Linder-Hampson system performs best at evaporation temperatures below −90 °C. • The seasonal energy efficiency ratio of Harbin is visibly higher than other cities. [ABSTRACT FROM AUTHOR]

Mobile phone data help us to understand human activities. Researchers have investigated the characteristics and relationships of human activities and regional function using information from physical and virtual spaces. However, how to establish location mapping between spaces to explore the relationships between mobile phone call activity and regional function remains unclear. In this paper, we employ a self-organizing map (SOM) to map locations with 24-dimensional activity attributes and identify relationships between users' mobile phone call activities and regional functions. We apply mobile phone call data from Harbin, a city in northeast China, to build the location mapping relationships between user clusters of mobile phone call activity and points of interest (POI) composition in geographical space. The results indicate that for mobile phone call activities, mobile phone users are mapped to five locations that represent particular mobile phone call patterns. Regarding regional functions, we identified nine unique types of functional areas that are related to production, business, entertainment and education according to the patterns of users and POI proportions. We then explored the correlations between users and POIs for each type of area. The results of this research provide new insights into the relationships between human activity and regional functions. • We establish location mapping between mobile phone call attribute space and geographical space. • We calculate correlations between clustered mobile phone users and POIs at base station area scale. • We find high correlations between user activities and regional functions (production, business, entertainment and education). • We find users' mobile phone call activities are extremely different between rural and urban areas. [ABSTRACT FROM AUTHOR]