A General Epidemic Model and Its Application to Mask Design Considering Different Preferences towards Masks

Table 1

The definition of mathematical symbols.

Symbol	Definition
	The number of susceptible individuals never wearing a mask.
	The number of infected individuals never wearing a mask.
	The number of recovered individuals never wearing a mask.
	The number of susceptible individuals wearing a mask if and only if infected.
	The number of infected individuals wearing a mask if and only if infected.
	The number of recovered individuals wearing a mask if and only if infected.
	The number of susceptible individuals always wearing a mask.
	The number of infected individuals always wearing a mask.
	The number of recovered individuals always wearing a mask.
	The number of individuals in the system.
	The number of new individuals entering the system within unit time.
	The rate of natural death.
	The rate of recovering.
	The rate of human-to-human infection.
	The fraction of new individuals never wearing a mask.
	The fraction of new individuals wearing a mask if and only if infected.
	The fraction of new individuals always wearing a mask.
	The protective effect produced when an infected individual wears a mask.
	The protective effect produced when a susceptible individual wears a mask.