Yanhua Yang Wenfeng Hu Consensus of Double-Integrator Multi-Agent Systems with Directed Networks and Nonuniform Communication Time Delays. 1229-1234 2020 ICCA https://doi.org/10.1109/ICCA51439.2020.9264565 conf/icca/2020 db/conf/icca/icca2020.html#YangH20