A definition of passive linear network is made:(a) The network is linear. (b) If currents of any wave form are fed to the terminals of the network, the total energy delivered to the network is not negative.(c) No voltages appear between any pair of terminals before a current is fed to the network.When this definition is applied to two terminal networks, i.e., impedances, a necessary and sufficient condition that a two-terminal network be linear passive is that its impedance function be a positive real function.An analysis of multiterminal networks yields as a necessary and sufficient condition from the foregoing hypotheses that a certain Hermitian quadratic form be positive definite. In the case of three-terminal networks, it reduces to 4RuRu-(R!2+ R2,)i-(X 12-X 2 ,)t;;::O, where Rij+jXij=Z'i are the terms of the matrix of impedances of the network. The relation of this formula to similar but not identical formulas of Gewertz and Llewellyn, and other consequences of the condition, are discussed.

The heart of this paper is some examples of how an inept choice of a measure of effectiveness has led an analyst (usually me) into error. Its tone is less solemn than that of most published papers, chiefly because it is about mistakes, and the only way that I know of to live with my own mistakes is to laugh at them. The morals to be drawn from these experiences are first, I, and many others, have erred more often by devoting too little effort into selecting measures of effectiveness than by devoting too much; and second (a corollary), in assigning resources and making schedules for an operational analysis, it is usually worth allocating more effort to finding measures of effectiveness even if you have to take it away from the other parts of the analysis.

No abstract

No abstract

The formula for the attenuation of a coaxial line loaded continuously with magnetic materials involves, after a change of variables, only three parameters, even when the effect of dielectric losses is included. If the dimensions of the line have their optimum values, the attenuation is a function of only two parameters. The relation is exhibited both graphically and analytically, in forms which can be applied to practical problems. A simple numerical example is given to illustrate the use of the formula.