Sets and indices O set of electricity...

Sets and indices
$O$	set of electricity coal loading ports, $o \in O$
$D$	set of electricity coal unloading ports, $d \in D$
$T$	set of operating years, $t \in T$
$S$	set of owned ships, $s \in S$
Parameters
$q_{o, d}^{t}$	annual average demand of electricity coal from loading port $o$ to unloading port $d$ in the $t$ th year
$γ_{s}$	estimated residual value rate of ship $s$
$l_{s}$	estimated available life of ship $s$
$w_{t}$	actual cargo capacity of own fleet in the $t$ th year
$G_{s}$	purchasing price of ship $s$
$K$	average cargo carrying capacity of unit owned fleet
$Γ_{t}$	average voyage time of unit own fleet in the $t$ th year
$δ_{s t}$	indicator of whether the ship is still in operation in the $t$ th year
${c_{t s}^{1}, c_{t s}^{2}, c_{t s}^{3}, c_{t s}^{4}, c_{t s}^{5}, c_{t s}^{6}, c_{t s}^{7}}$	ship's operating costs in the $t$ th year, representing the crew's wages, insurance premiums, insurance and indemnity fees, ship maintenance fees, ship moisturizing fees, ship material fees and management fees in the $t$ th year
${c_{t o}^{8}, c_{t d}^{9}}$	port charges of the loading port and the unloading port in the $t$ th year
$χ_{t}^{1}$	refueling amount of heavy oil in the $t$ th year
$χ_{t}^{2}$	refueling amount of light oil in the $t$ th year
$μ_{t}$	opportunity loss ratio of own fleet in the $t$ th year
${\tilde{ξ}}_{t}^{1}$	expected price of heavy oil in the $t$ th year
${\tilde{ξ}}_{t}^{2}$	expected price of light oil in the $t$ th year
${\tilde{F}}_{t}$	expected coal freight rate in the $t$ th year
Decision variable
$R_{t}$	proportion of self-owned fleet capacity in year $t$
Derived variables
$C_{t}^{1}$	annual capital cost of self-owned ship
$C_{t}^{2}$	operating costs of self-owned ship in the $t$ th year
$C_{t}^{3}$	voyage costs of self-owned ship in the $t$ th year
$C_{t}^{4}$	rental cost of chartered vessels in the $t$ th year
$C_{t}^{5}$	opportunity loss for self-owned capacity in the $t$ th year
$x_{t}$	optimal capacity of electricity coal for self-owned fleet in year $t$
$y_{t}$	optimal capacity of electricity coal for chartered ships in year $t$
$η_{t}$	optimal number of ships in the self-owned fleet in year $t$

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Sets and indices
$O$	set of electricity coal loading ports, $o \in O$
$D$	set of electricity coal unloading ports, $d \in D$
$T$	set of operating years, $t \in T$
$S$	set of owned ships, $s \in S$
Parameters
$q_{o, d}^{t}$	annual average demand of electricity coal from loading port $o$ to unloading port $d$ in the $t$ th year
$γ_{s}$	estimated residual value rate of ship $s$
$l_{s}$	estimated available life of ship $s$
$w_{t}$	actual cargo capacity of own fleet in the $t$ th year
$G_{s}$	purchasing price of ship $s$
$K$	average cargo carrying capacity of unit owned fleet
$Γ_{t}$	average voyage time of unit own fleet in the $t$ th year
$δ_{s t}$	indicator of whether the ship is still in operation in the $t$ th year
${c_{t s}^{1}, c_{t s}^{2}, c_{t s}^{3}, c_{t s}^{4}, c_{t s}^{5}, c_{t s}^{6}, c_{t s}^{7}}$	ship's operating costs in the $t$ th year, representing the crew's wages, insurance premiums, insurance and indemnity fees, ship maintenance fees, ship moisturizing fees, ship material fees and management fees in the $t$ th year
${c_{t o}^{8}, c_{t d}^{9}}$	port charges of the loading port and the unloading port in the $t$ th year
$χ_{t}^{1}$	refueling amount of heavy oil in the $t$ th year
$χ_{t}^{2}$	refueling amount of light oil in the $t$ th year
$μ_{t}$	opportunity loss ratio of own fleet in the $t$ th year
${\tilde{ξ}}_{t}^{1}$	expected price of heavy oil in the $t$ th year
${\tilde{ξ}}_{t}^{2}$	expected price of light oil in the $t$ th year
${\tilde{F}}_{t}$	expected coal freight rate in the $t$ th year
Decision variable
$R_{t}$	proportion of self-owned fleet capacity in year $t$
Derived variables
$C_{t}^{1}$	annual capital cost of self-owned ship
$C_{t}^{2}$	operating costs of self-owned ship in the $t$ th year
$C_{t}^{3}$	voyage costs of self-owned ship in the $t$ th year
$C_{t}^{4}$	rental cost of chartered vessels in the $t$ th year
$C_{t}^{5}$	opportunity loss for self-owned capacity in the $t$ th year
$x_{t}$	optimal capacity of electricity coal for self-owned fleet in year $t$
$y_{t}$	optimal capacity of electricity coal for chartered ships in year $t$
$η_{t}$	optimal number of ships in the self-owned fleet in year $t$