  The possibilities of application of such boundary functionals of random
processes as extreme values of these processes, the moment of first reaching a
fixed level, the value of the process at the moment of reaching the level, the
moment of reaching extreme values, the time of the process staying above a
fixed level, and other functionals to the description of physical, chemical and
biological problems are considered. Definitions of these functionals are given
and characteristic functions of these functionals are written for the model of
exponential distribution of incoming demands. The possibilities of using
boundary functionals are demonstrated using examples of a unicyclic network
with affinity A, an asymmetric random walk, nonlinear diffusion and multiple
diffusing particles with reversible target-binding kinetics.
