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Showing papers by "Polytechnic University of Milan published in 1986"



Journal ArticleDOI
TL;DR: A parametric method for autoregressive (AR) auto- and cross-spectral analysis is presented for the contemporaneous processing of heart rate and arterial blood pressure variability signals and the introduced bivariate spectral analysis provides quantitative and objective means which are useful to measure the role played by the neural controlling systems on the cardiovascular signals under different pathophysiological conditions.

294 citations


Journal ArticleDOI
01 May 1986
TL;DR: The paper presents the problem of fault tolerance in VLSI array structures, and two different approaches are presented, both based upon introduction of simple patterns of faults and by global reconfiguration techniques.
Abstract: The paper presents the problem of fault tolerance in VLSI array structures: its aim is to discuss architectures capable of surviving a number of random faults while keeping costs (in terms of added silicon area and of increased processing time) as low as possible Two different approaches are presented, both based upon introduction of simple patterns of faults and by global reconfiguration techniques (rather than one-to-one substitution of faulty elements by spare ones) Various solutions are compared, and relative performances are discussed in order to determine criteria for selecting the one most suitable to particular applications

170 citations


Journal ArticleDOI
TL;DR: In this paper, the displacement of a beam can be conveniently resolved into a roto-translational section displacement and a section warping, and the correct second order approximation of the strain is deduced accounting for large displacements and thus for large rotations.
Abstract: The displacement of a beam can be conveniently resolved into a roto-translational section displacement and a section warping. The correct second order approximation of the strain is deduced accounting for large displacements and thus for large rotations. On the basis of displacement method, both linear and nonlinear formulations are given: the first one leads to the elastic section properties and to the correct characterization of section warping; the second one leads to the so-called geometric section stiffness, accounting for prestress. Both formulations are general with respect to elastic material properties, thus allowing to deal with aniso-tropic and unhomogeneous cross-sections. Elastic and geometric section rigidities here proposed can then be easily used in second order problems on beam frames: either initial buckling eigenvalue analyses, either large displacement incremental analyses.

138 citations


Journal ArticleDOI
TL;DR: In this article, the authors exploit the finite element technique in the time domain in order to generate, by an automated procedure, a numerical approximation of the nonlinear periodic equations peculiar to the dynamics of helicopter rotors.
Abstract: Starting from a variational formulation, based on Hamilton's principle, the paper exploits the finite element technique in the time domain in order to generate, by an automated procedure, a numerical approximation of the nonlinear periodic equations peculiar to the dynamics of helicopter rotors. With this method, a unified approach is developed, which can be used to solve both the response and stability problem. Two simple examples are presented that show how the method can be used to study the trimmed response of a fully articulated rigid blade and the mechanical instability analysis of a four-bladed rotor.

95 citations


Journal ArticleDOI
TL;DR: In this article, progress in testing semiconductor drift detectors is reported, and it is shown that they are becoming versatile and reliable detectors for position and energy measurements, mainly due to new electronics better matched to different detectors.
Abstract: Progress in testing semiconductor drift detectors is reported. Generally better position and energy resolutions were obtained than resolutions published previously. The improvement is mostly due to new electronics better matched to different detectors. It is shown that semiconductor drift detectors are becoming versatile and reliable detectors for position and energy measurements.

94 citations


Journal ArticleDOI
TL;DR: In this paper, the concept of zero for linear discrete-time SISO periodic systems is discussed and the definition is based on a time-invariant MIMO equivalent representation.
Abstract: In this note the concept of zero for linear discrete-time SISO periodic systems is discussed. The definition is based on a time-invariant MIMO equivalent representation. An input-output characterization of the zeros is provided which extends a well-known property for time-invariant systems.

80 citations


Book ChapterDOI
01 Jan 1986

79 citations


Journal ArticleDOI
TL;DR: This dissertation aims to provide a history of web exceptionalism from 1989 to 2002, a period chosen in order to explore its roots as well as specific cases up to and including the year in which descriptions of “Web 2.0” began to circulate.

77 citations


Book ChapterDOI
01 Jan 1986
TL;DR: A survey of the state-of-the-art on half-space problems in kinetic theory is given in this paper, with particular concern for existence, uniqueness and closed form representations of the solutions.
Abstract: A survey of the state-of-the art on half-space problems in kinetic theory is given, with particular concern for existence, uniqueness and closed form representations of the solutions

69 citations


Journal ArticleDOI
TL;DR: In this paper, the structural evolution of the textile-clothing industry is mainly the result of organizational innovations to economize on transactional costs and increase the dynamic efficiency of firms.
Abstract: This paper argues that the structural evolution of the textile-clothing industry is mainly the result of organizational innovations to economize on transactional costs and increase the dynamic efficiency of firms. The rise of managerial hierarchies in the coordination of diversified activities, the drop in the number of vertical hierarchical arrangements and the diffusion of intermediate governance structures are the main changes in industrial organization. There is evidence from the Italian industry which supports this trend.


Journal ArticleDOI
TL;DR: In this paper, the electrochromic properties of thin film electrodes, obtained by a deposition on a tin oxide coated glass substrate of a TiO 2 dispersion in polyvinyl alcohol, were examined.

Journal ArticleDOI
TL;DR: In this article, the authors analyze the rate of the international diffusion of modems as well as structural determinants and suggest that the systematic character of new information technologies may become a factor in widening the technological cap between followers and leaders on international markets.

Journal ArticleDOI
TL;DR: The results reveal the advantages that can be obtained by modeling dynamic processes by DYLAM, especially when dealing with operator interventions in incident control and mitigation.
Abstract: The dynamic logical analytical methodology (DYLAM) modeling and analysis techniques are discussed, and its principal features are compared with those of the fault tree technique for reliability analysis. The study is performed with reference to the auxiliary feedwater system of a 1300-MW (electric) pressurized water reactor plant. The results reveal the advantages that can be obtained by modeling dynamic processes by DYLAM, especially when dealing with operator interventions in incident control and mitigation.

Journal ArticleDOI
TL;DR: In this paper, it was shown that the pressure conditions required in a non-fractional-step scheme to formulate the problem as a system of split second-order equations are of an integral character and similar to the previously discovered integral conditions for the vorticity.

Journal ArticleDOI
TL;DR: In this article, a priori data concerning the covariance of density anomalies is introduced to solve the inverse gravimetric problem, which is equivalent to requiring the density to fulfil a minimum norm condition.
Abstract: Summary. The determination of the density distribution of the Earth from gravity data is called the inverse gravimetric problem. A unique solution to this problem may be obtained by introducing a priori data concerning the covariance of density anomalies. This is equivalent to requiring the density to fulfil a minimum norm condition. The generally used norm is the one equal to the integral of the square of the density distribution (L2-norm), the use of which implies that blocks of constant density are uncorrelated. It is shown that for harmonic anomalous density distributions this leads to an external gravity field with a power spectrum (degree-variances) which tends too slowly to zero, i.e. implying gravity anomalies much less correlated than actually observed. It is proposed to use a stronger norm, equal to the integral of the square sum of the derivatives of the density distribution. As a consequence of this, base functions which are constant within blocks, are no longer a natural choice when solving the inverse gravimetric problem. Instead a block with a linearly varying density may be used. A formula for the potential of such a block is derived.

Journal ArticleDOI
TL;DR: The program presented here implements several normalization algorithms and is suitable for the interactive design of small database applications and as a teaching aid.
Abstract: A program for the normalization of relations that is written in Prolog has several advantages relative to programs written in conventional programming languages: notably, conciseness and clarity. The program presented here implements several normalization algorithms and is suitable for the interactive design of small database applications and as a teaching aid.

Journal ArticleDOI
TL;DR: Time-resolved fluorescence spectroscopy was performed on hematoporphyrin derivative in buffer at different concentrations of surfactants, with fluorescence decay time constants of ≈0.7 and ≈2.7 ns and emission peaks at 630 and 675 nm, respectively as discussed by the authors.

Journal ArticleDOI
TL;DR: This work considers as objective function the maximum difference between the weights of components in a spanning tree and presents an efficient algorithm to achieve the optimum or prove that the problem is NP-hard.

Journal ArticleDOI
TL;DR: Surface distribution maps of auditory evoked brainstem potentials are presented and are shown to be fully consistent with the results of two approaches that have been recently proposed for the analysis of AEBPs, namely dipole localization methods and three-channel Lissajous trajectories, thus confirming the technical feasibility of methods for extracting information on the sources ofAEBPs from surface data.

Journal ArticleDOI
TL;DR: In this article, the Lyapunov and Riccati differential equations with periodically time-varying coefficients are considered under the assumption of detectability of the underlying periodic system and two inertia theorems are provided linking the inertia of the solution to the so-called monodromy matrix.
Abstract: The Lyapunov and Riccati differential equations with periodically time-varying coefficients are considered. Under the assumption of detectability of the underlying periodic system, two inertia theorems are provided linking the inertia of the solution to the one of the so-called monodromy matrix.

Journal ArticleDOI
TL;DR: A novel stochastic self-tuning control algorithm for multivariable linear systems described by Controlled Autoregressive Integrating Moving Average models is proposed, which ensures the robust offset rejection for any constant load disturbance acting on the plant.

Journal ArticleDOI
TL;DR: Polymerisation du butadiene et de l'isoprene dans different solvants (hydrocarbures, paraffines, olefines, composes aromatiques) as discussed by the authors.
Abstract: Polymerisation du butadiene et de l'isoprene dans differents solvants (hydrocarbures, paraffines, olefines, composes aromatiques)

Journal ArticleDOI
01 Nov 1986-Polymer
TL;DR: In this paper, the authors used morphological and crystallographic properties to predict fold models for a perfect crystal of isotactic polypropylene (α-form) and showed that the folding plane must be parallel to the (010) plane.

Proceedings ArticleDOI
01 Dec 1986
TL;DR: An overview of optimal periodic control and periodic systems analysis can be found in this article, with special emphasis on the results achieved in the last decade, where the main issues are: Necessary and sufficient optimality conditions.
Abstract: This paper is an overview of optimal periodic control and periodic systems analysis, with special emphasis on the results achieved in the last decade. The main issues are: Necessary and sufficient optimality conditions. Quasi-stationary and high frequency periodic control. Proper periodicity. Structural properties of linear periodic systems. Periodic solutions to the periodic Riccati equation.

Journal ArticleDOI
TL;DR: In this article, the reachability and controllability indices at time t for discrete-time linear systems with periodic coefficients of period T were defined and a subspace of reachability subspace over the interval (t − (μrt−1) T, t) [(t, t + (μcr−1), T + μct, T)] was established.

Journal ArticleDOI
TL;DR: In this paper, the transformation austenite martensitique is inhibited by suite de la formation de nitrure par transfert de charge a partir du fer ou du chrome vers le tungstene.

Journal ArticleDOI
TL;DR: In this article, the canonical decomposition of discrete-time linear systems based on reachability, controllability, observability, and reconstructibility is studied and a sufficient condition for the existence of such a decomposition is worked out.
Abstract: The paper deals with the canonical decomposition of discrete-time linear systems based on the classical properties of reachability, controllability, observability and reconstructibility. First, a set of relationships between the structural subspaces is established and used to derive a general form of the discrete-lime duality principle. By means of these results, a sufficient condition for the existence of a canonical decomposition is worked out. Such a condition is also necessary if the attention is focused on decompositions based on the classical structural properties. Depending on the pair of properties considered, four different decompositions can be achieved. Finally, by making reference to controllability and reconstructibility a canonical decomposition is shown to exist for periodic systems. In general, non-reversible periodic systems admit no other decomposition but this one.

Journal ArticleDOI
TL;DR: In this paper, two short-term predictors of the winter electric load in a large Italian district are described: ARMA and ARMAX with weather inputs such as temperature and illumination.