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With the obvious regionalization trend in the new period of urbanization in China, the scientific delineation of functional regions (FRs) at different scales has become a heated topic recently. Since the 20th century, western academia has formed a basic idea of metropolitan areas’ (MAs) delineation based on population density and commuting rate, for which the subjectivity of threshold setting is difficult to overcome. In this study, community detection algorithms from the field of network science are employed, namely the Louvain algorithm with adjustable resolutions and Combo with high-precision output, respectively. We take the nationwide car-hailing data set as an example to explore a bottom-up method for delineating regional economic geography at different scales based on the interconnection strength between nodes. It was found that most of the prefecture-level cities in China have a dominant commuting region and two or three secondary commuting sub-regions, while regional central cities have extended their commuting hinterlands over jurisdictional boundaries, which is not common due to the larger initial administrative divisions and the comprehensive development niveau of cities. The feasibility and limitation of community detection partitioning algorithms in the application of regional science are verified. It is supposed to be widely used in regional delimitation supported by big data. Both of the two algorithms show a shortage of ignorance of spatial proximity. It is necessary to explore new algorithms that can adjust both accuracy and spatial distance as parameters.

Fast development of space technologies poses a strong demand for elastic materials that are lightweight, strong, but compliant to achieve high density of elastic energy storage, and such properties need to be temperature-insensitive in space environments [1][2][3][4] . However, existing materials do not meet this demand.Here we report a lightweight magnesium-scandium (Mg-21.3 at. % Sc) alloy meeting this demand. It is as light and compliant as organic-based materials like bones and glass ber reinforced plastics, but stronger than them [5][6][7] ; thus, it exhibits a record-high elastic energy density ~0.5 kJ/kg among various metallic and organic-based composite materials at a moderate stress level of 200 MPa 8,9 . Importantly, the performance can persist for 1 million stress cycles and over a wide temperature range from ambient to cryogenic temperatures. Its exceptional properties stem from a strain-glass transition. In-situ microstructure observations during cooling show strain-glass nanodomains continuously form from the matrix phase, which enables low modulus, high strength, fatigue-resistance, and temperature-insensitivity.The lightweight strain-glass Mg-Sc alloy may nd applications in space technologies and other elds such as orthopedics 1,9-11 . Main TextMagnesium alloys have the lowest density (ρ ~2 g/cm 3 ) among all metallic structural materials, being comparable with a number of organic-based natural or arti cial materials like bones, hard wood and glass ber reinforced plastics (GFRP) 6,7,12,13 . Therefore, they have the potential to be a solution to various lightweight elastic components in space technologies such as tires, springs and seals 1-3 . These applications require a high weight-speci c elastic energy density (i.e., elastic energy per unit weight) under a moderate stress level (e.g., ~200 MPa) 4,8,9 and such a property needs to be insensitive to temperature changes (e.g., 290-120 K in Mars) 4 . As the weight-speci c elastic density U is de ned as U=σ 2 /2ρE, where σ denotes the stress and E the elastic modulus, a promising candidate material needs to possess a combination of low density, low modulus and high strength, together with the property stability over a wide temperature range. However, existing Mg-alloys are challenged by a trade-off relation between elastic modulus and strength (see Fig. 1) [14][15][16][17][18][19][20][21][22][23][24][25][26] , which precludes achieving low modulus and high strength simultaneously; meanwhile the desired property stability over a wide temperature range is challenged by the inevitable hardening of metallic bonding with decreasing temperature.Recently, shape-memory effect and superelasticity have been reported in a Mg-20.5 at. % Sc (Mg-20.5Sc) shape-memory alloy (SMA), as a result of a martensitic transformation 27 . Although the large superelasticity provides a possibility for lightweight elastic energy storage, the Mg-20.5Sc alloy possesses the same drawbacks of other SMAs 28 -the inherent temperature sensitivity of superelasticity and thus a narrow wo...