和 means addition(+)

On pages 21 and 22 of the below PDF file the wording “summation relations” and “the present summation relation of equation (44) was applied to the data…” appears.
Please click on to the below file:
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A general stagnation-point convective-heating equation for ...
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summation relation involving the heat-transfer coefficients of the base gases. The basic technique developed for the prediction of stagnation-point ...
ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.../19720003329_1972003329.pdf

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/1972000...

Here are the Japanese and English definitions of 総和 as "summation."
http://ja.wikipedia.org/wiki/総和
数学において、総和（そうわ、summation）とは与えられた数を総じて加えることである。
http://en.wikipedia.org/wiki/Summation
Summation is the operation of combining a sequence of numbers using addition; the result is their sum or total. An interim or present total of a summation process is termed therunning total. The numbers to be summed may be integers, rational numbers, real numbers, or complex numbers, and other types of values than numbers can be added as well: vectors,matrices, polynomials, and in general elements of any additive group (or even monoid). For finite sequences of such elements, summation always produces a well-defined sum (possibly by virtue of the convention for empty sums).

相互関係と総和関係: individual relationship and overall relationship