Showing papers by "Polytechnic University of Milan published in 1973"
TL;DR: In this article, a "FZm Deviation" (FD) method for non-linear, unconstrained m.c. 1 fZm problems is proposed, which is quite similar to the gradient method for functions of continuous variables.
Abstract: mo problems reZevant to the design of a store-and-forward communication network (the message routing problem and the channeZ capacity assignment problem) are formulated and are recognized to be essentiaZ Zy non- Zinear, uncoMnA;tcained muZticomodity (m. c. 1 fZm problems. A "FZm Deviation" (FD) method for the soZution of these non-linear, unconstrained m.c. fZm probZems is described which is quite simiZar to the gradient method for functions of continuous variables; here the concept of gradient is repZaced by the concept of "shortest route" flow. As in the gradient method, the application of successive flow deviations leads to ZocaZ minima. of the FD method to the design of the ARPA Computer Network are discussed. FinaZ ly, two interesting applications
564 citations
TL;DR: In this paper, the optimal constant control of a given plant (with respect to a specified performance index and subject to equality and/or inequality constraints) can be improved by cycling and a frequency domain approach is followed in order to establish a general condition, which, in the particular case of single-input systems, admits a simple geometric interpretation.
Abstract: The problem is discussed of establishing whether the optimal constant control of a given plant (with respect to a specified performance index and subject to equality and/or inequality constraints) can be improved by cycling. A frequency domain approach is followed in order to establish a general condition, which, in the particular case of single-input systems, admits a simple geometric interpretation. Connections with high frequency and slowly varying periodic control problems are also pointed out.
157 citations
TL;DR: In this article, the key place of the choice of the bilinear form in order to give a variational formulation to a given problem is discussed, and a critical survey of the three main methods that was devised in the past to solve the same problem is done.
Abstract: The paper shows the key place of the choice of the bilinear form in order to give a variational formulation to a given problem. In particular it is shown how the use of a convolution bilinear form makes possible a variational formulation for linear initial value problems. A critical survey of the three main methods that was devised in the past to solve the same problem is done.
103 citations
TL;DR: New results in the theory of non-serial dynamic programming are described and their computational relevance is pointed out.
54 citations
01 Jan 1973
TL;DR: In this paper, the dynamic elastoplastic response to a given history of rapidly variable loads and imposed strains and displacements (dislocations) is studied on the basis of a suitable matrix description.
Abstract: Some broad classes of discrete structural models and piecewise linear yield loci and hardening rules are considered. The dynamic elastoplastic response to a given history of rapidly variable loads and imposed strains and displacements (“dislocations”) is studied on the basis of a suitable matrix description. Inadaptation means that the plastic work and, hence, some plastic deformations increase unlimitedly in time, i.e. the structure does not shakedown. Sufficient and necessary conditions for this occurrence are established and formulated in a theorem, which represents the extension to the dynamic range and to work-hardening structures of the second (Koiter's) shakedown theorem of classical plasticity.
47 citations
TL;DR: Dae polimeri reticolati di nuova sintesi, contenenti gruppi amminici terziari, sono in grado di assorbire selettivamente eparina dal sangue.
Abstract: Dae polimeri reticolati di nuova sintesi, contenenti gruppi amminici terziari, sono in grado di assorbire selettivamente eparina dal sangue. Essi non sono emolitici e non interferiscono con i fattori della coagulazione.
45 citations
42 citations
TL;DR: In this article, it was shown that MnMoO4 exhibits a polyfunctional nature; it is possible to distinguish the properties of isomerization, dehydrogenation, oxidation with oxygen insertion, and complete oxidation by varying parameters such as temperature, oxygen concentration and contact time.
38 citations
TL;DR: In this article, the authors formulated the finite analysis problem with piecewise linear constitutive laws as a linear complementarity and a quadratic programming problem, and proposed a solution technique using the well-known optimization methods of mathematical programming.
32 citations
TL;DR: The surface acidic sites and the formation of CO and CO2 were attributed to the pressence of bonds of covalent type in Bi2WO6 which has a rather polar structure as mentioned in this paper.
24 citations
TL;DR: In this article, the principal modes of vibrations of T beams taking into account torsional and flexional coupling are determined based on trasfer matrices for determining the principal mode of vibrations.
Abstract: Description of a method of calculation based on trasfer matrices for determining the principal modes of vibrations of T beams taking into account torsional and flexional coupling.
TL;DR: An unstable ring resonator has been studied, both theoretically and experimentally; quasi-traveling-wave operation is obtained with a high ratio of the powers of the two opposite rotating waves and with diffraction-limited output beams as mentioned in this paper.
Abstract: An unstable ring resonator has been studied, both theoretically and experimentally; quasi-traveling-wave operation is obtained with a high ratio of the powers of the two opposite rotating waves and with diffraction-limited output beams.
TL;DR: Exchange perturbation theory of the Rayleigh-Schrodinger type is applied, in first and second orders, to the problem of bonding in rare-gas halides.
Abstract: Exchange perturbation theory of the Rayleigh-Schrodinger type is applied, in first and second orders, to the problem of bonding in rare-gas halides. The basic model is that of a four-electron, three-center system with one effective electron replacing the unpaired electrons of a halogen atom, and two spin-paired electrons representing the closed shells of the rare-gas atom. On the basis of exchange perturbation theory, the model verifies a direct parallelism between bonding in rare-gas compounds and the phenomenon of super-exchange in ionic solids with paramagnetic cations. It is found that the observed stability and specific geometric configuration of the xenon and krypton fluorides are readily reproduced by the model. In addition, the model explains why other dihalides cannot exist. The two principal components of the interaction energy are found to be indirect exchange between halogen atoms via the rare-gas atoms (attractive in the stable configurations) and, in compounds with coordination higher than two, simultaneous interactions between three halogen atoms (always repulsive). The observed approximate constancy of the binding energy per bond in xenon fluorides with increasing coordination is accounted for.
TL;DR: The periodic optimization problem of maximizing the output power of a linear system under a control power constraint is analyzed and the explicit form of the optimal solution is found by means of a frequency domain approach.
TL;DR: The spectra of vic-dihalo-2,3oxazabicyclo[320]-hept-3-enes were analysed and the sign of all the coupling constants determined by tickling experiments as mentioned in this paper.
Abstract: The spectra of vic-dihalo-2,3-oxazabicyclo[320]-hept-3-enes were analysed and the sign of all the coupling constants determined by tickling experiments Stereochemical assignments, and three and four-bond coupling are discussed in particular
TL;DR: In this article, struts with differing geometrical characteristics and various slendernesses are considered, compressed axially and, at the same time, bent in an orthogonally symmetrical plane by moments of opposite direction and equal value applied at the ends.
Abstract: In this paper struts with differing geometrical characteristics and various slendernesses are considered, compressed axially and, at the same time, bent in an orthogonally symmetrical plane by moments of opposite direction and equal value applied at the ends.
TL;DR: In this paper, a simplified analytical model is proposed and the problem of intangibles is discussed and the conclusion reached is that a fundamental index for comparison and decision is the incremental cost of investment necessary to save, on average, one human life a year.
Abstract: The proper choice of the acceptable seismic risk requires an accurate cost-benefit analysis. As is well known these analyses present considerable difficulties if one wishes to face the problem in a general way from the technical point of view. Besides, there are no generally accepted criteria for formulating a quantitative evaluation of the intangibles, among which the most important is the risk to human life. However, it appears indispensable that research should be started in the field which leads to some numerical results
In this paper a simplified analytical model is proposed and the problem of intangibles is discussed. The basic idea is that the comparison with other risks is the most realistic instrument for the choice of an acceptable level of the specific considered risk. The conclusion reached is that a fundamental index for comparison and decision is the incremental cost of investment necessary to save, on average, one human life a year. An evaluation of such an index, valid as a first approximation, is given for this simplified model.
TL;DR: In this paper, a tentative model of Ca ejection from inclusions within the Ag crystallites was proposed to yield the cross-sectional area of the process and the experimental rate coefficient for this hereto-fore unobserved Ca ejections event was extracted.
07 May 1973
TL;DR: A new description of SSPS is proposed, called syntactic description, which constitutes a framework useful to structure a rich content of informations about a given problem.
Abstract: In this paper we have proposed a new description of SSPS, called syntactic description, which constitutes a framework useful to structure a rich content of informations about a given problem.
01 Jan 1973
TL;DR: The evolution of a mathematical model of the vestibulo-ocular system in an attempt to match more and more experimental data is followed and the final model explains many characteristics of the eye movement in vestibularly induced nystagmus.
Abstract: The vestibulo-ocular system is examined from the standpoint of system theory. The evolution of a mathematical model of the vestibulo-ocular system in an attempt to match more and more experimental data is followed step by step. The final model explains many characteristics of the eye movement in vestibularly induced nystagmus. The analysis of the dynamic behavior of the model at the different stages of its development is illustrated in time domain, mainly in a qualitative way.
TL;DR: Several algorithms are described that transform the figure into another one of the least possible dimensions, but retaining a set of basic topological and quasi-topological characteristics of the original picture, and are particularly suited for hardware implementation.
TL;DR: In this paper, Neutron activation analysis has been employed for the characterization of Samian ware sherds, which were classified in ten groups, seven of which belonged to the Arretine production, according to archaeological evidence.
Abstract: Neutron activation analysis has been employed for the characterization of Samian ware sherds. The analysed samples were classified in ten groups, seven of which belonged to the Arretine production, according to archaeological evidence. By means of high resolution gamma-ray spectroscopy, 22 elements have been identified and analysed. Compositional characterization was looked for by taking counting rate ratios of different nuclides in the samples. The compositional pattern of the sherds was found to be fairly uniform both for each pot and for each group so that, at least in the examined cases, it can be assumed to be characteristic of a given workshop.
TL;DR: In this paper, the first derivatives of the energy distribution curves of PbTe spectra were measured and compared with previous measurements and with existing band calculations, revealing new structures in the photoelectric spectra of pbTe with photons in the energy interval between 6.25 and 8.75 eV.
TL;DR: The problem of the insensitivity regulator, i.e., the regulator which allows the output or the state of a time-invariant linear system not to be affected by small parameter variations, is discussed in this paper.
Abstract: The problem of the insensitivity regulator, i.e. the regulator which allows the output or the state of a time-invariant linear system not to be affected by small parameter variations, is discussed in this paper. The possibility of solving this problem contemporarily with other classical regulator problems is also discussed.
TL;DR: In this paper, a set of fissile nuclides has been used for the determination of the epicadmium spectrum at the centre of the core of the L54 reactor.
07 May 1973
TL;DR: In this paper the analysis of particular message switching networks is performed taking into account the finite storage at nodes.
Abstract: In this paper the analysis of particular message switching networks is performed taking into account the finite storage at nodes.
07 May 1973
TL;DR: This work deals with trees, showing how the algorithm for finding the shortest spanning tree of a graph can be modified to handle some problems of this kind efficiently.
Abstract: When two weighting figures per arc must be considered in optimizing a network one has either to combine them in a single performance factor or to optimize the network with respect to one of them while respecting some constraint on the other. This work deals with trees, showing how the algorithm for finding the shortest spanning tree of a graph can be modified to handle some problems of this kind efficiently.