Abstract: A method and a system for detecting heavy metal ions are provided. The method includes: fixing a pre-manufactured micro-electrode chip on a connecting device, connecting the connecting device to an electrochemical workstation, carrying out setting before detection on the electrochemical workstation, the micro-electrode chip including a counter electrode and a working electrode, carrying out graphene modification treatment on the counter electrode in advance, and carrying out bismuth film modification treatment on the working electrode in advance; and carrying out acid pretreatment on an aqueous solution to be detected, dropwise adding 5 µL to 100 µL of a treated aqueous solution to a working area of the pre-manufactured micro-electrode chip, measuring an I-V curve by the electrochemical workstation subjected to the setting before detection, and determining species and concentrations of heavy metal ions in the aqueous solution according to peak values of voltage and current of the I-V curve.

Abstract: The present invention discloses a method for rendezvous of unlicensed users having multiple transceivers in cognitive radio networks, including four stages: an initial stage: setting an initial communication environment; a stage of selecting a rendezvous method: selecting a method for generating a channel hopping sequence according to the quantity of transceivers; a stage of generating a channel hopping sequence: using a single-transceiver rendezvous method or a multiple-transceiver rendezvous method to generate a channel hopping sequence; and a rendezvous stage: running, by an unlicensed user, on a corresponding channel and attempting to rendezvous with a destination node of the unlicensed user, where if rendezvous is achieved, the rendezvous process ends; and if rendezvous is not achieved, the rendezvous process continues until rendezvous is achieved.

Abstract: The present invention discloses a method for rendezvous of unlicensed users having multiple transceivers in cognitive radio networks, including four stages: an initial stage: setting an initial communication environment; a stage of selecting a rendezvous method: selecting a method for generating a channel hopping sequence according to the quantity of transceivers; a stage of generating a channel hopping sequence: using a single-transceiver rendezvous method or a multiple-transceiver rendezvous method to generate a channel hopping sequence; and a rendezvous stage: running, by an unlicensed user, on a corresponding channel and attempting to rendezvous with a destination node of the unlicensed user, where if rendezvous is achieved, the rendezvous process ends; and if rendezvous is not achieved, the rendezvous process continues until rendezvous is achieved.