Showing papers by "Polytechnic University of Turin published in 1969"

Suggestion for an i.c. fast parallel multiplier

Abstract: A general method for handling partial products in a parallel multiplier is proposed. It leads to a network of AND gates and full adders, availables as i.c.s which can have an operation time of less than 10 ns per bit of the result.

Saturation approach law for grain-oriented polycrystalline magnetic materials

Abstract: The saturation approach law in grain-oriented polycrystals of cubic materials is studied, taking into account the magnetic interactions among grains, as a function of the crystalline magnetic anisotropy constants K 1 and K 2 , and of a grain dispersion parameter τ. This parameter gives in the two limits \tau \rightarrow 0 and \tau \rightarrow \infin a single crystal and a perfectly isotropic polycrystal, respectively. The effect of internal stresses is also taken into account, and it is shown to have little influence on the saturation approach law, which, in grain-oriented materials, is dominated by the spread of the grain distribution. The obtained results suggest one of the most sensitive methods for determining such a spread in these materials from saturation approach measurements, particularly when τ is very small. The made assumptions on the grain distribution are general enough to obtain as particular cases, the Goss texture, the cubic texture, and the fiber texture. Examples of application of the theory to practical cases of grain-oriented Fe-Si 3- percent laminations are given.

Directional ordering as a source of coercive force and asymmetry of the loop

Abstract: The effect of directional order, formed by annealing in the demagnetized state, on the coercive force of ferromagnetic materials susceptible to magnetic anneal, is examined quantitatively. It is shown that in many magnetic materials, especially Fe-Ni alloys, this is the major source of coercivity. Experimental results are reported on the following alloys: Fe-6.4 percent Si with zero magnetostriction λ and large magnetocrystalline anisotropy constant K ; 60 percent Ni-40 percent Fe with fairly large λ. and low K ; Mumetal (77.5 percent Ni-13.5 percent Fe-5 percent Cu-4 percent Mo) with nearly zero values of both λ and K . The coercive force increase resulting from the formation of a local induced anisotropy K u , with the easy axis along the magnetization direction within each domain and domain wall, is found to vary linearly with the induced anisotropy field K_{u}/J_{s} , through a proportionality factor of the order of 0.1. This figure is shown to be in good agreement with the value predicted by the known theories which relate the coercive force to the fluctuation of the Bloch wall energy, when the contribution of an induced uniaxial term due to the formation of a random directional order is taken into account. Furthermore, in agreement with the fact that the viscosity field is also proportional to the anisotropy energy associated with directional orders a close proportionality is experimentally found to exist between the frozen-in viscosity field measured on a constricted loop and the increase of coercive force which is observed when the wasp-waisted shape of the loop is destroyed by demagnetizing the specimen. It is finally shown that materials characterized by directional anisotropy formation can show asymmetrical hysteresis loops, when properly annealed in a magnetic state corresponding to the vertex of a nonsaturated loop.

An “ideal equivalent gas method” for the study of shock waves in supersonic real gas flows

Abstract: A method developed by the author for the systematic study of the thermodynamic and dynamic properties of the gas behind a shock wave is reported.

Waveform transmission with permutation modulation

Abstract: The permutation-modulation scheme proposed by Slepian is applied to waveform transmission. The system performances are described in terms of output signal-to-noise ratio, and a comparison is made with a p.c.m./f.s.k. system.

Structure of a strong normal shock wave due to nonequilibrium radiation and collisional ionization

Abstract: The general theory about gas-dynamics with nonequilibrium radiative and collisional ionization is applied to the strong normal shock wave. It is shown that the problem is reduced to the solution of a system of two non-linear integral equations. It is proved that, if certain conditions are satisfied, an iteration method, to resolve these equations, can be applied; it turns out then that the fundamental parameter controlling the convergence or non convergence of the procedure is the value of the degree of ionization a just on the front of the shock. Numerical results are given and the physical complete structure of the shock is analized.

Sulla elaborazione statistica di dati sperimentali per misure indirette

Abstract: Si espone una applicazione del criterio di massima verosimiglianza per la stima dei parametri di un sistema di relazioni implicite, lineari nelle grandezze misurabili e non lineari nei parametri stessi Si dimostra che se le grandezze osservabili sono affette da errori con distribuzione di probabilita multinormale e valore sperato nullo, e possibile pervenire a equazioni risolutive abbastanza semplici in cui compaiono come incognite soltanto i parametri da stimare e non i valori «veri» delle grandezze misurate Si fornisce anche una espressione della matrice di covarianza dei soli parametri incogniti

Improved program for multiple regression analysis

Abstract: A modification is introduced into the computer program for multiple regression analysis due to Efroymson. When a variable is to be tested for either introduction into or removal from the regression equation, the relevantF level is calculated recursively for the effective degrees of freedom instead of assuming a fixed value. The test of significance is therefore carried out exactly at the level specified, no matter how many variables are introduced in the final equation.

A Sensitive Half-Shadow Ellipsometer

Abstract: The ellipsometer described herein uses a He–Ne laser as monochromatic light source, and, in the analysis system, a sensitive elliptic detector namely the Bravais-Zakrzewski-Perucca biplate. The use of this biplate allows better accuracy in measurements. Furthermore, a method of measuring and evaluating the results is described which includes, but is not limited to, conventional methods.

Gravity effect of a homogeneous hemisphere

Abstract: Finite expressions for the gravity effect of a homogeneous hemisphere are given, considering the two cases when the hemispherical surface is convex upward and downward, the base plane being horizontal. Sets of theoretical gravity profiles and other graphs are also given: they may be used for the quantitative interpretation of Bouguer residual gravity anomalies which may be taken as due to hemispherical geological bodies. The results of an investigation on the convergence of the series expansion used for the evaluation of the Heuman's Lambda Function are also presented.

L'Effet de la Stimulation Avec une Bande de Bruit Blanc sur le Jugement D'Hauteur de L'Oreille Contralatérale

Abstract: ResumeOn expose les resultats des mesures de jugement d'hauteur des sons purs homolateraux, de frequence entre 100 et 6000 Hz, avec stimulation contralaterale constituee soit par une bande etroite de bruit blanc, soit par un son pur, de la měme frequence et du měme niveau de pression sonore du son homolateral.Les variations d'hauteur qu'on trouve dans les deux cas sont comparees entre eux; les donnees de la deuxieme serie sont aussi comparees avec les donnees des mesures analogues de Thurlow. Les resultats des trois series sont tres voisins jusqu'a 1000 Hz; aux frequences plus hautes on trouve une augmentation d'hauteur avec le bruit blanc controlateral, une diminution avec le son pur (au contraire de Thurlow a 4000 Hz). Cette difference de comportement de l'oreille peut ětre interpretee comme un phenomene psychologique, du a la difference d'attention (plus haute avec le bruit blanc), c'est-a-dire a un phenomene central.This study concerns the pitch judgement of pure homolateral sounds, between 100 and 60...

Flows on two-dimensional networks

Abstract: A “two-dimensional network”Gb is here defined as an extension of an ordinary network (of the Graph Theory), whose arcs have an associate given direction, i.e. a vectorb ofR2 such that ¦b¦2=1.