Showing papers by "Polytechnic University of Turin published in 1978"
TL;DR: In this article, a deep investigation of the ideal b * generated by the initial forms of the elements of an ideal A of a local ring, with respect to a certain ideal a.
Abstract: Hironaka, in his paper [H 1 ] on desingularization of algebraic varieties over a field of characteristic 0, to deal with singular points develops the algebraic apparatus of the associated graded ring, introducing standard bases of ideals, numerical characters ν* and τ* etc. Such a point of view involves a deep investigation of the ideal b * generated by the initial forms of the elements of an ideal A of a local ring, with respect to a certain ideal a .
246 citations
TL;DR: In this paper, a new model is proposed to explain the mechanism of complete suspension of solid particles in cylindrical flat-bottomed stirred tanks, which is mainly due to turbulent eddies of a scale of the order of the particles size.
224 citations
TL;DR: In this paper, the mixed finite element approximation of variational inequalities is studied, taking as model problems the so-called "obstacle problem" and "unilateral problem".
Abstract: We study the mixed finite element approximation of variational inequalities, taking as model problems the so called "obstacle problem" and "unilateral problem" Optimal error bounds are obtained in both cases
196 citations
TL;DR: The interpretation of facility location as an optimization problem not only gives theoretical support to some well-known location algorithms but also shows how to generalize and improve them.
Abstract: A mathematical-programming approach to facility location is developed. The objective function assumed for optimization is an accessibility measure. It is shown that, by suitably defining this measure, one can get solutions closely related to, if not identical with, the ones given in many current formulations of the location problem. This is believed to be an interesting result in itself, as it shows how the programming approach can unify different strands of research in this field. Moreover the mathematical-programming tools allow a deep analysis of the properties of the solution points, which can be difficult with other methods. Also the interpretation of facility location as an optimization problem not only gives theoretical support to some well-known location algorithms but also shows how to generalize and improve them. /Author/TRRL/
71 citations
TL;DR: In this paper, it is shown that a different basis should be used for different aspects of the determination of E, the energy required to produce a unit area of fragment surface, which is independent of time though the mass abrasion rate is greatest initially when the particle asperities are being removed.
58 citations
TL;DR: In this paper, the role of gravity waves in the troposphere is briefly discussed and reviewed, and the physical processes involved in the interaction of gravity wave with mesoscale and planetary boundary layer phenomena are discussed.
Abstract: The nature and the role of gravity waves in the troposphere is briefly discussed and reviewed. After describing some basic properties of gravity waves and their generation mechanisms, we analyze their ability to influence phase changes, trigger and organize convective cells, to produce and interact with turbulence, and to affect diffusive processes in the atmosphere. Throughout, the emphasis is placed on the physical processes involved in the interaction of gravity waves with mesoscale and planetary boundary layer phenomena. Also discussed and reviewed are those remote sensing devices which are particularly useful in revealing and measuring such waves. Finally, an attempt is made to outline possible lines of future work for the purpose of fully understanding the role of gravity waves in mesoscale and microscale dynamics.
49 citations
46 citations
TL;DR: In this article, a model of conduction mechanism in discontinuous metal films which gives the temperature dependence of conductivity over a very large temperature interval, from -250 to 450, and explains the origin of the conductivity fluctuations responsible for the current noise in these films is presented.
Abstract: A new model of conduction mechanism in discontinuous metal films which gives the temperature dependence of conductivity over a very large temperature interval, from -250 to 450\ifmmode^\circ\else\textdegree\fi{}C, and explains the origin of the conductivity fluctuations responsible for the current noise in these films is presented. It is shown that the conductivity change with temperature is due to a shift of the position of the Fermi level at the surface of the insulator. This changes the height of the potential barrier which must be overcome by tunneling of the conduction electrons. Such a shift, required at each temperature to ensure electron thermal equilibrium, is generated by a partial depletion of surface donor states located on the insulator surface between metal islands. It is further shown that the fluctuation of the surface charge created by the ionization of the surface states modulates the height of the tunneling barrier giving rise to a corresponding modulation of the electrical conductivity originating the current noise typical of discontinuous films. In paper II the results of the theory are compared with experiments.
43 citations
29 citations
TL;DR: In this paper, a new approach to the problem of power loss calculation in ferromagnets is provided, which takes into account the effect of the irreversible jumps of the Bloch walls during magnetization.
Abstract: A new approach to the problem of power loss calculation in ferromagnets is provided, which takes into account the effect of the irreversible jumps of the Bloch walls during magnetization. The magnetization process of the material under cyclical conditions is treated as a random function of time and separated into two components: a) a periodic component which gives rise to a line spectrum and is related to the classical dynamic loss; b) a random component which has a continuous power spectrum and which is responsible for both the total static loss and the anomalous dynamic loss. Bloch walls correlation effects are discussed in relation to the change of this last component and its related losses under different physical conditions.
28 citations
TL;DR: In this article, the decomposition of the whole system in subsystems suitably connected is considered, in which the checking of structural identifiability or the analysis of unidentifiable parameters is of great interest.
Abstract: Most of the work available in the literature deals with the problem of checking the identifiability of a given model structure. However two problems must often be faced in practical applications : first, as the structure to be examined increases in complexity, the proposed procedures become computationally unfeasible ; secondly, in cases where identifiability cannot be achieved, a more detailed analysis of what can be identified is of great interest. In this paper some class of model structure will be considered, in which the decomposition of the whole system in subsystems suitably connected really simplifies the checking of structural identifiability or the analysis of unidentifiable parameters.
01 Feb 1978
TL;DR: In case of small pistons without a forced cooling system at the inside face of piston, most of the heat flows out of piston toward cylinder line through the sliding surface of piston ring and piston. as discussed by the authors showed that fluttering of piston way receives heat in a reciprocating way on rear and upper surface.
Abstract: When power output of automobile engine increases adverse effects resulting from increase of heat load on piston become serious. For a cooling countermeasure it is necessary to clarify the path along which heat is transfered and to be familiar with heat coming from the top surface of piston. In case of small pistons without a forced cooling system at the inside face of piston, most of the heat flows out of piston toward cylinder line through the sliding surface of piston ring and piston. The research results make evident that fluttering of piston way receives heat in a reciprocating way on rear and upper surface. A set of graphs represent thermal field change in twelve moments of operating cycle. /SASI/
TL;DR: A recognizer of isolated words spoken in the Italian language is presented and is based on a classification of speech units into broad phonetic classes, eventually followed by a classification into more detailed classes if some ambiguities still remain.
TL;DR: In this article, the authors proposed a kinetic theory to study the aerodynamic properties of convex bodies in molecular flow, which can describe both the scattering kinetics and the adsorption-desorption kinetics.
Abstract: This paper proposes a kinetic theory to study some important features of the aerodynamics of convex bodies in molecular flow. In particular, the proposed theory can describe both the mechanics of the scattering kinetics and of the adsorption-desorption kinetics in the interaction between the free-molecule stream and the surface of the body. The obtained result ought to be considered a more rigorous physicalmmathematical model than the one proposed by preposed by previous known theories, which, also because of the physical and mathematical difficulty of the problem, can describe only one, separately, of the two aspects of the problem (the scattering or the adsorption-desorption processes). Moreover the previous theories require the aid of disposable parameters, unknowna priori. On the other hand, in this work, the final result consists in a, unequivocally determined, scattering kernel which correlates the distribution function of the particles re-emitted by the surface to the distribution function of the arriving particles, for a gas monochromatic stream interacting with an aluminium surface at satellite speed. This result is then applied to calculate the aerodynamic forces and the heat flux acting over convex bodies of arbitrary geometry.
TL;DR: In this article, the joint distributions of economic parameters corresponding to "optimum" conditions (minimum cost, and maximum production rate), as affected by a single tool wear mechanism, are analyzed and the information process is examined using a Bayesian approach.
Abstract: The joint distributions of economic parameters corresponding to ″optimum″ conditions (minimum cost, and maximum production rate), as affected by a single tool wear mechanism, are analyzed and the information process is examined using a Bayesian approach. Results obtained for an example show that even scanty experimental evidence may be profitably exploited
01 Jan 1978
TL;DR: In this article, a simple machining operation is modeled according to some management choices by stochastic simulation, taking into account two main tool failure mechanisms, and the effects of tool change schedule, production block size and sudden failure on production rate and cost are assessed.
Abstract: A simple machining operation is modeled according to some management choices by stochastic simulation, taking into account two main tool failure mechanisms. Under the assumption that premature tool failures account for either work interruption or production of defective pieces, the effects of tool change schedule, production block size and sudden failure on production rate and cost are assessed. Some minimum regions are found for expected values of dependent variables, which have no counterpart for upper bound values
TL;DR: In this paper, a theoretical analysis of the stability of Rabi and Ramsey interrogation methods in divergent beams is given, and upper limits for the stability obtainable in both configurations, with given beam intensity and detection efficiency, and for the frequency at which that maximum is reachable in mechanically collimated beams.
Abstract: A theoretical analysis is given of the stabilities obtainable with Rabi and Ramsey interrogation methods in divergent beams. The performances of both techniques in frequency standard applications are strongly degraded by first order Doppler effect when the divergence is such that the beam width becomes comparable with the transition wavelength. Upper limits exist for the stability obtainable in both configurations, with given beam intensity and detection efficiency, and for the frequency at which that maximum is reachable in mechanically collimated beams. Non-mechanical collimation (e.g. saturated absorption) should be used in order to reach that maximum at higher frequencies. Doppler-free interrogation methods appear to be the only way to remove these upper limits.
TL;DR: In this paper, a global stability theory is introduced as a tool allowing the classification of mathematical models of phase transitions, where a topological structure whose stability controls the transition, can be identified in the process of computation of the partition function.
Abstract: Global stability theory is introduced as a tool allowing the classification of mathematical models of phase transitions. The point of view is that a topological structure whose stability controls the transition, can be identified in the process of computation of the partition function. In particular we discuss mean field theories and the two dimensional Ising model.
Interesting features are disclosed concerning the classification of the instabilities, such as the number of parameters and possible approximations.
TL;DR: In this paper, a simple machining operation is modeled according to some management choices by stochastic simulation, taking into account two main tool failure mechanisms, and the effects of tool change schedule, production block size and sudden failure on production rate and cost are assessed.
Abstract: A simple machining operation is modeled according to some management choices by stochastic simulation, taking into account two main tool failure mechanisms. Under the assumption that premature tool failures account for either work interruption or production of defective pieces, the effects of tool change schedule, production block size and sudden failure on production rate and cost are assessed. Some minimum regions are found for expected values of dependent variables, which have no counterpart for upper bound values
TL;DR: In this paper, the authors discussed the dependence of cosmic-ray transport in the interplanetary space on the polarity configuration of the solar and inter-planetary magnetic fields.
Abstract: In this paper we discuss the dependence of cosmic-ray transport in the interplanetary space on the polarity configuration of the solar and interplanetary magnetic fields. The diffusion mechanism is not only related to the irregularities present in the interplanetary magnetic field, but also to its regular structure, because of the curvature and gradient drifts of the particles. Hence diffusion is affected by the polarity reversals of the interplanetary magnetic dipole which are related to the reversals of the solar dipole. As a consequence a phase reversal of both the annual and semi-annual variations in the cosmic-ray intensity occurs. This effect has been studied throughout the period 1954–1976, by analysing the Climax neutron monitor data. In addition, the latitudinal distribution of the average solar activity itself in this period changes simultaneously to the polarity reversals of the solar polar fields.
TL;DR: A general method for evaluating, by linear analysis, the complete circuit performance is described that considers thermal feedback effects and can easily be implemented using only well known computer programs for the circuit analysis.
Abstract: It is well known that the behaviour of integrated circuits is strongly affected by thermal feedback. A general method for evaluating, by linear analysis, the complete circuit performance is described that considers these effects. The procedure can easily be implemented using only well known computer programs for the circuit analysis. Simple models for a number of devices (diodes, transistors and f.e.t.s) used in integrated circuits are given. Examples, using the circuit-analysis program ECAP, are shown.
TL;DR: In this paper, a linearization of the equations of the thermoviscoelastic field in the case of great temperature variations was developed and the possibility of uncoupling the heat equation from the motion equation was discussed.
01 Sep 1978-International Journal of Human-computer Studies \/ International Journal of Man-machine Studies
TL;DR: This paper describes a text-to-speech translation system for the Italian language based on a formal translator which converts a graphemic text into the corresponding phonemic representation and on a suprasegmental features descriptor.
Abstract: This paper describes a text-to-speech translation system for the Italian language. It is based on a formal translator which converts a graphemic text into the corresponding phonemic representation and on a suprasegmental features descriptor. The translator is implemented according to the formal techniques developed for lexical and syntactical analysis of artificial languages. The suprasegmental features descriptor determines pause positions, phoneme durations and pitch contour on the sole basis of the punctuation marks and the accent marks present in the text.
Proceedings Article•
18 Jul 1978TL;DR: The paper describes the organization of knowledge source and the algorithms for evaluating hypotheses of the front-end acoustic classifier of a Speech Understanding System.
Abstract: The paper describes the organization of knowledge source and the algorithms for evaluating hypotheses of the front-end acoustic classifier of a Speech Understanding System
TL;DR: This paper proposes an architecture where processors are tightly grouped in clusters, loosely linked to each other, and the whole structure is compatible with VLSI implementations of the processor modules.
TL;DR: In this paper, an operational issue arising in the use of spatial interaction models for solving actual planning problems is addressed, where an axiom about the concept of distance detterence is introduced and a calibration procedure is proposed.