Agglomeration 3 Beijing [China] 3 China 3 Economics Hebei 3 Tianjin 3 Urban agglomerations Sustainable development 2 agglomeration 2 economic development 2 spatiotemporal analysis 2 Beijing(Jing)-Tianjin(Jin)-Hebei(Ji) (JJJ) urban agglomeration 1 Beijing(jing)-tianjin(jin)-hebei(ji) (JJJ) urban agglomeration 1 Beijing-Tianjin-Hebei urban agglomeration (BTH) 1 Beijing-tianjin-hebei urban agglomeration (BTH) 1 CG-GSO model 1 Complex nexus 1 Comprehensive gravity-gram schmidt orthogonalization coupling model model 1 Coordination state 1 Coupling coordination index 1 Coupling models 1 Development modes 1 Ecological security 1 Ecological security index 1 Ecological security index (ESI) 1 Ecology 1 Economic and social effects 1 Economy-resource-environment system 1 Economy-resources-environment system 1 Environment systems 1