In the blockchain network, communication delay between different nodes is a great threat to distributed ledger consistency of each miner. Blockchain core technology Bitcoin. At present, some research has proven security PoW protocol when number rounds small, but in complex asynchronous networks, insufficient on large. This paper improves proposed main chain record model under and then proposes ...

The medium access control (MAC) protocol design of underwater acoustic sensor networks (UWASNs) faces many challenges: the power limitation at nodes, long propagation delay, low data rates, etc. These challenges of underwater acoustic channels result in the unsuitable usage of terrestrial networks MAC protocol in UWASNs. Moreover, the long propagation delay causes a serious problem for the MAC ...

wireless ad hoc networks are composed of independent nodes managing the network without any infrastructure. the connection between nodes is provided by sending packages and by trusting to each other. therefore, using efficient and certain protocols is the essential requirement of these networks. due to special characteristics of wireless ad hoc networks such as lack of a fixed infrastructure, t...

background: gnrh agonist and antagonist were developed to control the premature release of lh surge. there is some difference between two protocols. objective: we compared the outcome of frozen-thawed embryo transfer in infertile women who used gnrh agonist or antagonist protocol for previous coh cycle and evaluation of any adverse effect of gnrh antagonist on oocyte and embryo. materials and m...