  Blockchain stores information into a chain of "blocks", whose integrity is
usually guaranteed by Proof of Work (PoW). In many blockchain applications
(including cryptocurrencies), users compete with each other to win the
ownership of the blocks, a process commonly referred as "mining". Mining
activities consume huge amount of power, while the outcome appears to be
useless besides validating a block. Here we discuss the requirements of
designing a new PoW algorithm. We also propose a PoW scheme to help solve
high-dimension, non-linear optimization problems. Simulation experiments of
blockchains generated by three miners solved an instance of Traveling Salesman
Problem (TSP), a well-known NP-hard problem. The revised scheme enables us to
address difficult scientific questions as a byproduct of mining.
