Showing papers by "Polytechnic University of Turin published in 1972"

A Parallel Structure for Signed-Number Multiplication and Addition

Abstract: An algorithm for performing signed-number multiplications using positive-number full multipliers is presented It leads to very simple input-and output-correcting networks which are cellular iterative and introduce negligible additional delay

Low-temperature behavior of the spin-wave energy in the itinerant electron model of ferromagnetism

Abstract: An exact microscopic formula for the transverse dynamical susceptibility is derived from the spin rotation invariance properties of the model. The same properties allow the definition on a microscopic basis of the effective magnon-magnon interaction. As a concrete application of the above general results we calculate the low-temperature behavior of the spin-wave energy due to magnon-magnon interaction in the long-wavelength limit. For Ni in the parabolic band approximation and strong ferromagnetism limit we haveC2(K)=8.3×10−5T5/2K2 meV.

Simple circuit to double the output-voltage swing of an operational amplifier with increased slew rate

Abstract: A method of doubling the output-voltage swing and to increasing the slew rate of an operational amplifier is described. Two practical circuits and experimental results are given.

A Theory on the Latitude and Local Time Distribution of Precipitating Electrons During a Sudden Commencement

Abstract: The magnetic field compression during an SC excites VLF waves. In turn the wave turbulence drives the pitch angle diffusion of energetic electrons trapped in the magnetosphere, causing them to be precipitated into the lower ionosphere.

Influence of sample surface on thermomagnetic effects in Fe40-Ni60

Abstract: It is shown that the effect of an induced anisotropy energy due to directional order in Fe40-Ni60 is strongly dependent on the sample-to-volume ratio. Torodial samples of various thickness (6,3,1,0.5 mm) were machined from the same ingot, chemically etched, and annealed at 1300°C in H 2 . All further annealings were performed at 450°C in N 2 in one of the following magnetic conditions: a) demagnetized state; b) under magnetic field; c) remanent state. After these annealings loops show a constricted shape (a), a closely square shape with small coercive field H c (b), or a square shape with large H c (c). However, the width of the constricted region after annealing a), and the magnitude of H c after b) or c), are found to increase for decreasing sample thickness; in general, changes of loop shape induced by a given annealing are markedly stronger on thinner specimens. These differences are attributed to some influence of sample surface on the thermomagnetic treatment. This conclusion was further checked by electrochemically etching off a sample layer (0.01-0.1 mm); as a consequence the shapes of the loops obtained by the previous annealing suffered changes which were strongly different depending on the original thickness of the sample. It is qualitatively observed that the induction of a directional anisotropy energy K u occurs according to the domain pattern present during annealing, and that surface patterns are certainly characterized by smaller spacings of 180° domains and larger densities of 90° closure domains than are bulk patterns. Therefore the effectiveness on the loop shape of a K u distribution in a surface layer is stronger than the one of a K u distribution induced in a bulk layer. By etching off a sample layer, the new surface domain pattern bears little correlation to the old K u distribution, and there is a memory loss of previous annealing results, which is more pronounced on samples with larger surface-to-volume ratios.