Environmental Engineering Reference
In-Depth Information
Population Viability Analysis A mathematical tool often applied in conserva-
tion biology, which calculates the probability that a population becomes extinct
under a set of environmental conditions within a given time span.
Random Walk Mathematical description of a trajectory which is constructed
from successive random elements. In ecology it is often used to describe the
movement of organisms.
Self-Organization A process in which an overall systems state emerges from
parallel and distributed interaction of its constituent elements without any central
steering instance. Usually, nonlinear and nonequilibrium processes are involved.
Many ecosystem states can be described as a result of self-organized processes.
Social-Ecological Systems A combined system of social and ecological compo-
nents and drivers which interact and give rise to results which could not be
understood on the basis of sociological or ecological considerations alone.
Soft Computing An emerging computer science area, inspired by biological
systems and human mind, used to model complex systems arising in management
science, medicine, biology and ecology. It consists of a variety of techniques,
including fuzzy logic, neural networks, genetic algorithms, Bayesian networks.
They all differ from conventional (hard) computing since they tolerate uncertainty,
partial truth, approximation, lack of categoricity, and imprecision to achieve trac-
tability, robustness and low solution cost. Soft computing approaches emulate
characteristics of human reasoning such as the learning, training, and other types
of high-order cognitive power.
Square Matrix This is a matrix which has the same number of rows and columns.
An n
n-matrix is a square matrix of order n. The Identity Matrix I
n
is a square
matrix of order n in which all elements on the main diagonal are equal to 1 and
all other elements are equal to 0. The inverse A
-1
of a square matrix is defined as:
A
A
-1
= I
n
. If an inverse exists, A is called invertible or non-singular.
State Variable In dynamical systems, it is understood that the state of the system
is completely characterized by the states of the variables within the system.
Trophic Efficiency The ratio of production which relates one trophic level in
terms of energy and biomass with the adjacent level.
Trophic Level The hierarchical position which an organism occupies in the
trophic web structure.
Weibull Distribution A continuous probability distribution in statistics that is
used to describe, e.g. lifespans and failure rates of compound aggregates in analytical
quality assurance procedures.
