Michel G. Malti

Fractional-slot and dead-coil windings

THE expression “fractional-slot windings” is commonly applied to machines where the number of slots is not an integer multiple of the product of the number of poles and phases. Dead-coil windings (D.W.) refer to windings where some of the slots contain wedges instead of coil sides. We shall use the term (F.W.) in this paper to comprise all windings which are not (D.W.). The term (F.W.) therefore comprises both whole-slot as well as fractional-slot windings which contain no dead coils.

A Generalized Infinite Integral Theorem

A generalized infinite integral theorem and its transform and applications are presented in this paper in such form that it becomes unnecessary to use Duhamels theorem. The treatment embodies extensions to Heavisides methods of circuit analysis, thereby simplifying materially the mathematics of operational methods and giving a clearer insight into the connection between the physics and mathematics of transients. Extensions to Heavisides expansion theorem also are given.

Mathematics and Physics in Engineering

MANY definitions are given of an engineer. For the purpose of this discussion I would define an engineer as a scientist who uses physics and mathematics to promote the welfare of mankind. His use of physics and mathematics presupposes a thorough knowledge of them and demands that he be capable of:

Expansion Theorems for Ladder Networks

The well-known expansion theorem of Heaviside applies to circuits whose current-electromotive force relations may be expressed through differential equations, whereas in some networks such as filters and artificial lines, in which the network consists of a repeated pattern or mesh, the relations give what are known as difference equations. These are equations involving the mesh number of the network. The solutions of such networks are given in this paper in the form of expansion theorems similar to Heavisides expansion theorem and its extensions.

Support of endowed colleges by industry

Our colleges and universities find themselves in the paradoxical situation of financial needs that are rapidly becoming acute at a time when their usefulness has never been greater. An urgent plea is made for larger grants and heavier endowments, especially from business corporations, if our institutions of higher learning are to meet the needs of an exploding population and the technological challenge from the Soviet Union

Mathematics in engineering — A new policy

ENGINEERING, and particularly electrical engineering, has become a science whose future progress depends largely on the extensive use of mathematics and physics. In the writers early experience it was not unusual to hear prominent engineers state that the place for an integral sign is the violin. The use of complex numbers in circuit analysis, the introduction of operational and transform methods, and the application of tensor analysis in electrical engineering have brought to our profession the realization that not only the integral sign, but also other mathematical hieroglyphics, are indeed just as essential to the engineer as they are to the mathematician.

Reports of five technical conferences held during the Summer convention

TO PROVIDE opportunity for the direct informal interchange of ideas on subjects of a specialized nature among specialists and others interested in such subjects, five technical conferences were held during the AIEE 1938 winter convention. Brief reports of these conferences are presented here. These reports were prepared by the conference chairmen, or from notes furnished by them, except the conference on education, which was prepared by the conference secretary.

Usefulness of mathematics in engineering

Mr. C. J. Holslags letter in the May 1938 issue of Electrical Engineering on “Preparation of Manuscripts” calls for comments particularly since he himself invites them.

Abridgment of a theory of imperfect solid dielectrics

This paper covers Chapters VII, VIII and IX of a thesis presented by the author to the Faculty of the Graduate School of Cornell University, for the degree of Doctor of Philosophy. In this thesis a summary is made of the experimental facts regarding the anomalous behavior of solid insulating materials under varying conditions of potential, time, temperature, frequency, humidity, ionizing radiations and various other factors. A bibliography containing about 400 articles dealing with experimental and theoretical research is appended to the thesis. These articles are chronologically arranged and numbered. Five tables are given, including references to experimental research done on (a) dielectric resistivity, (b) dielectric charge and discharge, (c) dielectric constant, (d) dielectric strength, (e) dielectric energy loss. Hypotheses are here established which account, in a general way, for the observed behavior of solid dielectrics. Definitions of the resistivity, permittivity, electric charge and electric strength of solid dielectrics under both continuous and alternating potentials are submitted. Terms are introduced and defined: e. g., the “(i — t)-characteristic,” the “electrization curve,” and the “hystero-viscosity loop.” The various energy losses occurring in dielectrics are traced to their sources and subdivided into hysteresis, viscosity and resistance losses. Methods are devised for separating the total dissipated energy into its three component parts. Finally, the classical theory is shown to apply to imperfect solid dielectrics if the submitted definitions and terms be adopted.