Nyquist -- Swedish -- 1927
Kotelnikov -- Russian
Zhukovskii (Joukowski) -- Russian
In mathematics today the conformal mapping of the complex
plane z z + 1/z is called the Joukowski transformation.
This gave Zhukovskii :-
... a means of designing aerofoils using conformal
mappings and the techniques of complex variables. Those
Joukowski aerofoils were actually used on some aircraft, and
today these techniques provide a mathematically rigorous
reference solution to which modern approaches to aerofoil
design can be compared for validation.
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He formalized the already known results (due to Whitaker, Kotelnikov,
Hartley, and Nyquist) and mentions at the front of one of his papers on
sampling that these ideas are known to anyone skilled in the art. But he is
the one that connects them together in a formal sense. Also he goes on to
define entropy (as applied to information and not thermodynamics) and then
provides both the noiseless and noisy coding theorems, both of which are
"A Mathematical Theory of Communication" A must read for DSPers
His complete bibliography:
Hurewicz was Polish, but born under the Czar's rule.
From http://www-history.mcs.st-and.ac.uk/Mathematicians/Hurewicz.html :
"Witold Hurewicz's father was an industrialist. Witold attended school
in a Russian controlled Poland but with World War I beginning before he
had begun secondary school, ..."
From http://www.ling.upenn.edu/courses/ling525/z.html :
"A method for solving linear, constant-coefficient difference
equations by Laplace transforms was introduced to graduate engineering
students by Gardner and Barnes in the early 1940s. They applied their
procedure, which was based on jump functions, to ladder networks,
transmission lines, and applications involving Bessel functions. This
approach is quite complicated and in a separate attempt to simplify
matters, a transform of a sampled signal or sequence was defined in 1947
by W. Hurewicz as
[not reproduced here]
which was later denoted in 1952 as a "z transform" by a
sampled-data control group at Columbia University led by professor John
R. Raggazini and including L.A. Zadeh, E.I. Jury, R.E. Kalman, J.E.
Bertram, B. Friedland, and G.F. Franklin.
"The Hurewicz equation is not expressed in the same way as the z
transform we have introduced -- it is one-sided, and it is expressed as
a function of the sampled data sequence f rather than the complex number
z -- but the relationship is clear, and the applications were similar
from the beginning. So perhaps the z transform should really be called
the "Hurewicz transform".
"In any case, it is presumably not an accident that the z transform was
invented at about the same time as digital computers."
Make of this what you will. I first heard if Hurewicz in 1953 or so,
from an instructor who joked that symbolic logic is just "Booleshit".
Don't confuse him with Hurwitz.
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