6GCIoHE theoretical framework 6GIIoE applications 6GIIoE challenges 6GIIoE priorities 6GIIoE theoretical framework COVID-19 Environmental science, engineering & technology Industry 4.0 Technology: general issues artificial and human intelligence artificial intelligence assembly automotive industry applications bridge change management circular building circular economy circular resource flows civil engineering classification clustering cognitive data intelligence cognitive healthcare cognitive load cognitive manufacturing common welfare concurrent engineering construction construction engineering data science