Human User
Example: The employee in a supermarket loads the fridge with meat
instead of cheese. Therefore, he regulates the temperature of the fridge
accordingly. In this example, the employee is a Human User and the
fridge is a Physical Entity; Note: The case of multiple Human Users for one Physical Entity is
possible as well. We take the example of the safe in a bank. For security
reasons, more than one high-ranked employee is required to identify
themselves simultaneously at the safe in order to be able to open it. In
this example the eligible employees are Human Users and the safe is the
Physical Entity.Physical Entity
A Physical Entity is a discrete, identifiable part of the physical environment
which is of interest to the User for the completion of his goal. In the following
different kinds of Physical Entities are discussed.
Environment
Example: An optical fog sensor measures the density of water particles
in the air that limit visibility. This sensor is used for traffic-control
purposes, where it is often installed on the side of roads for monitoring
visibility impairment through fog. The information about the fog is sent to
a traffic management system where it is analyzed. In this example the
near surrounding above the road is the Physical Entity.Living being
Example: A WSN for agricultural monitoring. The network targets to
report on the growth of fruits. To this end growth monitors are deployed.
They are equipped with fruit-growth sensors as depicted in Figure 90. In
this example, the fruits are Physical Entities that are living beings.