Volume 13, Issue 8, 01 August 1942
Index of content:
13(1942); http://dx.doi.org/10.1063/1.1714900View Description Hide Description
The present theory of the suspension of vehicles is established on the assumption of perfect symmetry and of a linear dependence between elastic forces and the displacements of the wheels and deflections of the tires. The path of the vehicle rolling on uneven ground is supposed nearly straight, but no other important limitations are made in the fundamental hypothesis, so that the results cover any kind of suspension. The relative magnitude of the seven vibrations corresponding to bobbing, rolling, and pitching motions of the body, and to the four specific vibrations of the wheels, are discussed in view of their combined effects on the displacements of the body of the car. The general conclusion, which attempts to separate as much as possible the respective frequencies to avoid beats and also directly to improve comfort, is in accord with several practical experiments made in the industrial field.
13(1942); http://dx.doi.org/10.1063/1.1714901View Description Hide Description
A practical method is developed for calculating the distribution of scalar fields in axially symmetric systems. To obtain a complete solution a knowledge of the potential distribution along a cylinder of constant radius is required; in many cases the distribution along the cylinder can be estimated with sufficient accuracy by an inspection of the electrode configuration. The solution is first obtained in the form of an integral. This is evaluated for the class of boundary potential functions of the formIn this expression, Vn (1, z) is the potential along a cylinder of unit radius, z is measured along the axis of the cylinder, and n is a positive integer (zero included). Numerical values are given in tabular form for the cases n=0, 1, 2 and 3. It is then shown how the solution for the above boundary potential functions can be used to obtain the solution for an arbitrary distribution of potential along a cylinder of constant radius. In particular, the potential distribution of a simple electron lens consisting of two coaxial cylindrical electrodes of equal diameters is expressed in terms of the tabulated functions. The calculated equipotential lines for one such case are compared graphically with a plot made in an electrolytic plotting tank. The comparison between the calculated and experimental results is quite favorable.
13(1942); http://dx.doi.org/10.1063/1.1714902View Description Hide Description
The differential equations governing the longitudinal displacement and velocity of a uniform rod are identical to those governing the propagation of charge and current along a uniform electrical transmission line. By making use of this analogy between the rod and the transmission line, it is possible to translate some well‐known results of electrical circuit theory to mechanical terms. In this manner, and by the use of the operational calculus, interesting and useful results in the theory of longitudinal impact are obtained. The treatment is vastly simpler and more general than the classical theory of Saint‐Venant and Boussinesq and some of the results are thought to be new.
13(1942); http://dx.doi.org/10.1063/1.1714903View Description Hide Description
A new method for deriving the usual Poynting vector is given. This method also yields other equally valid energy flow vectors with the same or other equally valid postulated electromagnetic energy densities. Examples of such alternative Poynting vectors with their associated energy densities are given. A definition is given which distinguishes between the conduction and displacement currents in matter. It is shown that by addition of a term, the postulated energy flow widely used by electrical power engineers and based on wattmeter readings becomes a valid alternative Poynting vector.
13(1942); http://dx.doi.org/10.1063/1.1714904View Description Hide Description
The use of secondary electrons to obtain trigger action similar to that of a thyratron is described. An experimental tube and the necessary circuits by which this action is achieved are discussed. This combination gives the features of a triode with a relay or on and off feature, resulting in an amplifier,oscillator,modulator, or other vacuum tube device which may be turned on or off abruptly at high or low frequencies. In addition, it can be used to replace thyratrons in many of their circuits where very low impedance is not necessary and is capable of much greater speeds of operation in such applications.
13(1942); http://dx.doi.org/10.1063/1.1714905View Description Hide Description