Showing papers by "Polytechnic University of Turin published in 1976"
TL;DR: In view of the particular interest in the problem of reduced-order modeling in recent years, some considerations not sufficiently investigated in current literature are pointed out and a comprehensive set of references is given.
Abstract: In view of the particular interest in the problem of reduced-order modeling in recent years, some considerations not sufficiently investigated in current literature are pointed out and a comprehensive set of references is given.
177 citations
TL;DR: In this paper, the internal and external effective wetting of a porous catalyst in a trickle bed reactor was considered, and the internal diffusivity (Di)app was determined on the basis of a model which assumes a total external wetting.
119 citations
64 citations
TL;DR: The details of the implementation of a syntax-controlled acoustic encoder of a speech understanding system (SUS) are presented and it is shown that finite-state automata operating on artificial descriptions of suprasegmentals and global spectral features isolate syllables in continuous speech.
Abstract: The details of the implementation of a syntax-controlled acoustic encoder of a speech understanding system (SUS) are presented. Finite-state automata operating on artificial descriptions of suprasegmentals and global spectral features isolate syllables in continuous speech. Then a combinational algorithm tracks the formants for the voiced intervals of each syllable, and other algorithms provide a complete structural description of spectral and prosodic features for a spoken sentence. Such a description consists of a string of symbols and numerical attributes and is a representation of speech in terms of perceptually significant primitive forms. It contains all the information required to reconstruct the analyzed sentence with a formant synthesizer; it can be used directly either for emitting or verifying hypotheses at the lexical level of an SUS and for automatically learning phonetic features by grammatical inference.
49 citations
TL;DR: In this paper, it was shown that if A is an algebra of finite type over an arbitrary field k, the answer is positive, and the same result holds for any m-adic completion of an excellent ring A also excellent.
Abstract: In [2], chap. IV, 2me partie, (7.4.8), Grothendieck considered the following problem: is any m-adic completion of an excellent ring A also excellent? In [8] I proved that, if A is an algebra of finite type over an arbitrary field k, the answer is positive.
48 citations
TL;DR: A method for computing the error probability of multilevel baseband digital modulation systems when the channel is nonlinear with memory, based on a Volterra series expansion of the nonlinearity is presented.
Abstract: A good deal of effort has been spent, in the past few years, to devise numerical algorithms for evaluating the performance of digital communication systems over noisy linear channels, i.e., in the presence of intersymbol interference and noise. In this concise paper we present a method for computing the error probability of multilevel baseband digital modulation systems when the channel is nonlinear with memory. The algorithm is based on a Volterra series expansion of the nonlinearity; with this model, we show that the moments of the disturbance can be computed recursively, and the same techniques in use for linear channels can be applied for evaluating the error probability. This approach can be generalized to consider noise entering the nonlinear channel. The computing algorithms are described in detail, and a complete example is worked out.
32 citations
TL;DR: In this article, the feasibility of subjecting organic substances in waste waters to pyrolysis prior to their employment in purification of the water itself is reported, and the quality of the carbon obtained was determined with reference to its oil-carbon transformation yield, adsorption capacity, and residual hydrocarbon content.
18 citations
TL;DR: The problem of evaluating successively the discrete Fourier transform on ordered sets of N elements staggered of M is considered, and three procedures for solving such a problem are given, of which two are recursive and one nonrecursive.
Abstract: In this work the problem of evaluating successively the discrete Fourier transform (DFT) on ordered sets of N elements staggered of M is considered. Three procedures for solving such a problem are given, of which two are recursive and one nonrecursive. The complexity of each procedure, in number of complex multiplications, is about (N/2) \log_{2} 4M .
15 citations
TL;DR: In this paper, the static dielectric constant of nonpolar liquids is described by analyzing the pair distribution function and the dipole-dipole interaction into a finite set of Fourier components.
Abstract: The static dielectric constant of nonpolar liquids is described by analyzing the pair distribution function and the dipole-dipole interaction into a finite set of Fourier components. In a mean field approximation the theory leads to a final formula that does not contain any adjustable parameter, and proves to work better than the Clausius-Mossotti equation. The theory explains in a satisfactory way the temperature and pressure dependence of the dielectric constant of nonpolar liquids, as well as the temperature variation of the refractive index of many organic polar liquids.
14 citations
TL;DR: In this article, a statistical analysis of blister parameters (diameter and skin thickness) is used to investigate the internal structure of a deuteron beam ejected from the plasma, and the value K ∼ 10−20 keV is obtained as the typical ion energy for the bulk of the deuterons and an ion energy E ∼ 200−230 keV was typical for individual ion groups (ion strings) forming the high-energy ion beam.
12 citations
TL;DR: In this article, a new approach for the general study of 1.1 equations of type (1) is developed, consisting in the determination of the periodical steady solutions in a suitable parametric form with which the equation is transformed into a non linear integral equation.
Abstract: A new approach for the general study of the equations of type (1.1) is developed, consisting in the determination of the periodical steady solutions in a suitable parametric form with which the equation is transformed into a non linear integral equation. The procedure is developed in details in the case of the Duffing equation, for which it is obtained an approximate solution valid even if the non-linearity of the system is very high, based on the study of a Volterra integral equation.
TL;DR: In this article, the authors measured the power loss anomalies of a change of intrinsic parameters, such as crystalline anisotropy energy K, without affecting the extrinsic ones such as grain size and orientation.
Abstract: Measurements as a function of temperature t were performed on directional FeSi 3%, in order to study the possible influence on the power loss anomalies of a change of intrinsic parameters, such as crystalline anisotropy energy K, without affecting the extrinsic ones, such as grain size and orientation. Power losses per cycle P/f were measured vs. frequency f, between d. c. and 50 Hz at various temperatures ranging from 25 to 650°C. The variation of K and of saturation induction B s with t were also determined up to the Curie point by means of a torque magnetometer. The results show that the excess loss anomaly at 50 Hz, measured by the ratio of experimental to classical eddy-current loss, and the non-linearity anomaly, determined from the renormalized P/f vs. f curves, are essentially independent of t. Analogies with the temperature dependence of the power density spectrum of the Barkhausen noise, which varies according to a B_{s}^{2} (t) law, are briefly discussed. These results seem to indirectly stress the role of extrinsic parameters in determining the anomalous loss behaviors in directional FeSi 3%. Kerr observations made up to 350°C on a (300 × 30)mm2strip did not detect any change of stripe domain widths and patterns.
TL;DR: In this paper, the authors developed a complete mathematical model for the determination of the profile of an electrochemically machined workpiece when the shape of the tool and the machining conditions are known.
TL;DR: In this article, the transonic flow in axisymmetric choked nozzles is computed in the case of a radial distribution of tangential velocity by means of a time-dependent technique.
Abstract: The transonic flow in axisymmetric choked nozzles is computed in the case of a radial distribution of tangential velocity. The flow configuration is obtained by means of a time-dependent technique. The swirling flow is achieved through a particular surface located at the inlet of the nozzle. The pressure distribution and the sonic line are presented for choked flows without or with swirling.
TL;DR: It is shown that no dosed-loop controls can improve the open-loop min- max performance and the min-max feedback law is obtained.
Abstract: This paper considers the design of output regulators with the use of approximate models. The measure of the approximation between process and model outputs is represented by a bound in norm of the output error signals and it requires the computation of two numbers. The design is achieved with a rain-max approach where control and error signals are the two antagonists. The min-max solution is obtained as a linear function of the model state (open-loop solution). It is shown that no dosed-loop controls can improve the open-loop min-max performance. Conditions are given so as to preserve the min-max performance by means of proportional feedback of the system's output. In this case the min-max feedback law is obtained (closed-loop solution).
TL;DR: In this article, it was shown that the observability of a linear state equation, only input-output accessible, does not imply that all the states can be actually evaluated, such possibility, depends on the identifiability properties of the equations.
Abstract: It is shown that the observability of a linear state equation, only input-output accessible, does not imply that all the states can be actually evaluated. Such possibility, depends on the identifiability properties of the equations. A necessary, and sufficient condition for observability of the states, when the equations are unidentifiable, is derived. It is also shown that in such situations the "actual" observability' may depend also on the input matrix.
TL;DR: In this paper, the authors described the phenomenon of dielectric relaxation in polar liquids without employing the hypothesis of the Dielectric Continuity (DCL) and the final equation of the theory, which predicts the correct high frequency asymptotic behaviour of the complex DCL constant, is discussed with reference to the corresponding equation used by Lobo, Robinson and Rodriguez (1973).
Abstract: Through a formalism previously developed by the author in connection with the static problem, the phenomenon of dielectric relaxation in polar liquids is described without employing the hypothesis of the dielectric continuum. The final equation of the theory, which predicts the correct high frequency asymptotic behaviour of the complex dielectric constant, is discussed with reference to the corresponding equation used by Lobo, Robinson and Rodriguez (1973).
01 Jan 1976
TL;DR: In this paper, the supersonic flow about elliptic cones with very lar~ ratio R (R = i0) may be computed by using a proper set of variables and coordinate system, different from those assumed in other investigations.
Abstract: Large attention has bean paid at the numerical investigation of the supersonic flow about elliptic cones. By looking at the literature, many approaches have been used. Different formulations of the problem, sets of variables and coordinate systems have been selected. Nevertheless no solutions and reliable numerical results have been achieved for very thin coneS, namely for the ratio (R) of the semiaxis of the crossSection ellipse greater than 3.3 3.7. In this paper I would like to show how the supersonic flow about elliptic cones with very lar~ ratio R (R = i0) may be computed by using a proper set of variables and coordinate system, different from those assumed in other investigations.
TL;DR: On the basis of the parallel conductance model for solid-fluid turbulent mass transfer, a general approximate expression has been derived for calculating the enhancement factor F β due to instantaneous reaction as discussed by the authors.
TL;DR: In this article, a family of subsets of pure states of a generic physical system is singled out and used to extend the quantum-mechanical notion of superposition of the pure states.
Abstract: In the space of pure states of a generic physical system, a family ℒ of subsets is singled out and used to extend the quantum-mechanical notion of “superposition” of pure states. ℒ possesses a natural lattice structure and corresponds to the lattice of closed subspaces of Quantum Mechanics.
01 Jan 1976
TL;DR: The transonic shock-free flow past a given profile is here cal= culated with a direct procedure on the hodograph plane as discussed by the authors, and the numeri= cal results relative to the circular arc with various leading edges are reported in details.
Abstract: The transonic shock-free flow past a given profile is here cal= culated with a direct procedure on the hodograph plane. The numeri= cal results relative to the circular arc with various leading edges are reported in details. The financial support has been given by the Groups G.N.A.F.A. and G.N.F.M. of C.N.R.
TL;DR: In this paper, a new class of equal-ripple rational functions is considered for the design of lowpass transfer functions of RC active filters, using a critical pole pair with a multiplicity greater than unity (as in the MUCROMAF and MUCROER polynomials).
Abstract: A new class of equal-ripple rational functions is considered here for the design of lowpass transfer functions of RC active filters. Using a critical pole pair with a multiplicity greater than unity (as in the MUCROMAF and MUCROER polynomials), we can obtain lower pole Q-factors with this new class than with the classical Cauer functions.
TL;DR: In this paper, a model for mass transfer in the liquid phase in packed towers was proposed, and the relationship between the volumetric mass transfer coefficients in different operations: evaporation, physical absorption, chemical absorption.
TL;DR: In this paper, the authors propose a solution to the problem of non-necessairement lineaire in a non-constraint environment. But they do not specify a solution.
Abstract: On se propose d’approcher la solutionu de l’equation
$$\begin{gathered} \frac{{du}}{{dt}} + \Delta u = f, 0< t< T< + \infty \hfill \\ u(0) = u_0 \hfill \\ \end{gathered}$$
(1)
pourf etu0 donnes,A etant un operateur non necessairement lineaire.
TL;DR: In this article, the authors considered complementary instruments to X-ray diffraction or to neutron experiments in the structural studies of the liquid, which can be seen as complementary instruments for the metallurgical industry.
Abstract: Accurate viscosity measurements about metallic alloys, besides being of great interest for the metallurgical industry, can be considered complementary instruments to X-ray diffraction or to neutron experiments in the structural studies of the liquid.
TL;DR: In this paper, Cordierite glass powders, synthetized with 100 ppm platinum as a nucleating agent, were preheated at different temperatures from 600 to 900°C for different times (up to 5 hours) and were studied by X-ray diffraction, differential thermal analysis, scanning electron microscopy and IR absorption spectroscopy.
TL;DR: In this paper, the steady state vibrations of the wave form, amplitude and phase of the Duffing equation were studied by a procedure of direct numerical integration based on the Runge-Kutta method and by calculating the approximate solution of the equation which is obtained, as a particular case, from the theory developed in Part I.
Abstract: Numerical results on the wave form, the amplitude and the phase of the steady state solutions of the Duffing equation are obtained here. The steady state vibrations are studied:i) by a procedure of direct numerical integration based on the Runge-Kutta method;ii) by calculating the approximate solution of the equation which is obtained, as a particular case, from the theory developed in Part I. The results obtained by the two methods are compared and tested by the results of other Authors. From the comparisons it appears that the theory of Part I gives satisfactory results also in the cases of strong nonlinearity of the system.