Fuel-Efficient on-Orbit Service Vehicle Allocation Based on an Improved Discrete Particle Swarm Optimization Algorithm

Table 1

Nomenclature of variables.

Variable	Explanation
	Position vector
	Velocity vector
	Thrust
	OSV mass
	Specific impulse
	Thrust direction
	Terminal time of transfer trajectory
	Adjoint variables of position vector
	Adjoint variables of velocity vector
	Adjoint variable of the OSV mass
	Optimal thrust direction
	Maximum of thrust
	Switching-off time of the 1^st thrust segment
	Switching-on time of the 2^nd thrust segment
	Switching-off time of the 2^nd thrust segment
	Design parameters of transfer trajectory
	Population size of GA
	Crossover probability of GA
	Mutation probability of GA
	Maximum iterations of GA
	Count of OSVs
	Count of satellites
	Denotation of OSV
	Denotation of satellites
	Allocation matrix
	Maneuvering time
	Remaining fuel mass of after maintaining
	Population size of DPSO
	Number of satellites needed to be maintained
	Maximum iterations of DPSO
	Inertia weight
	Cognitive coefficient
	Social coefficient
h	Iteration counter
	Time step
	Mission duration
	Individual fitness extreme
	Global fitness extreme
	Length of the tabu table
	Size of the candidate set
	Maximum iterations of TS
	Candidate set
	Tabu table