Showing papers by "University of Patras published in 1975"
TL;DR: In this article, the existence and consistency of the MLE in the independent not identically distributed (i.n.i.d.) case was established and its asymptotic normality was established.
Abstract: In this paper, we assume the existence and consistency of the maximum likelihood estimate (MLE) in the independent not identically distributed (i.n.i.d.) case and we establish its asymptotic normality. The regularity conditions employed do not involve the third order derivatives of the underlying probability density functions (p.d.f.'s).
32 citations
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TL;DR: A method is described and implemented for the derivation of active RC filters from analogue passive filters of the lossless ladder doubly terminated kind using scattering-parameter formulation.
Abstract: A method is described and implemented for the derivation of active RC filters from analogue passive filters of the lossless ladder doubly terminated kind. The method is based on scattering-parameter formulation and the active RC filters thus derived are referred to as wave active filters.
31 citations
TL;DR: In this article, the 87 Sr 86 Sr ratios appear to increase in a general way with increasing depth to the Benioff zone and the strontium isotope ratios are higher than from most island arcs; this is believed to be due to contamination.
22 citations
TL;DR: In this paper, boundary value techniques were applied to the case of an electron performing relativistic motions within a magnetic dipole such as that of the Earth supplemented by a scanning process by means of which the entire phase space of the problem can be investigated.
Abstract: Application of boundary value techniques in the case of an electron performing relativistic motions within a magnetic dipole such as that of the Earth supplemented by a scanning process by means of which the entire phase space of the problem can be investigated, six new types of periodic motion have been discovered and computed. The stability of these motions is investigated and their direct bearing on formation and shape of the Van Allen zones of the Earth is discussed.
20 citations
TL;DR: In this article, the problem of designing a state feedback controller which drives the eigenvalues of a linear multivariable system to prespecified positions is studied, and the approach is that of transforming the system under control to a phase-variable canonical form prior to the application of the control design procedure.
Abstract: The problem of designing a state feedback controller which drives the eigenvalues of a linear multivariable system to prespecified positions is studied. The approach followed is that of transforming the system under control to a phase-variable canonical form prior to the application of the control design procedure. This transformation is possible only when the system is state-controllable which implies that it is also mode-controllable. The single-input design problem is first considered and solved by an elegant utilization of the concept of state similarity transformation. By this transformation one essentially converts the original problem of designing the state feedback modal controller matrix gain F to that of determining the associated similarity transformation T. The multi-input controller design problem is then treated by an extension of the above results which yield the most general state feedback modal controller possible. The state feedback modal controller derived is utilized, and the most gene...
20 citations
TL;DR: Isotopic ratios of strontium in 9 volcanic rocks from the south-eastern part of the Hellenic arc range from 0.7037 to 0.70075 as mentioned in this paper.
19 citations
TL;DR: The hypothesis is put forth that in systems where the number of self-sustained oscillating components may vary with time in such a way that the maximum entropy of the system increases faster than the overall instantaneous entropy, the system gets organized not just in spite of, but merely because of the presence of Noise.
Abstract: This paper deals with information transfer from the environment and "self"-organization in open, nonlinear systems far from thermodynamic equilibrium -- in the presence of either non-stationary phase jitter noise, or amplitude stationary noise. By "self"-organization we mean here the progressive formation within the system of sequential, ordered (coherent) relationships between appropriate dynamical variables-like for example, the phase differences between the oscillating components of the system. We take up (in Section II) the classical Laser as a specific example and examine in detail the influence of phase jitter noise in the mode (phase) locking process. We find--as expected--that phase fluctuations in the cavity cause degradation of the coherent behaviour (i.e. increase the entropy) of the system -- which, however, levels off, or saturates with time. Further (in Section III) we examine systems where the number of self-sustained oscillating components may vary with time in such a way that the maximum entropy of the system increases faster than the overall instantaneous entropy. We put forth the hypothesis that in such cases -- because of the increase of the redundancy -- the system gets organized not just in spite of, but merely because of the presence of Noise. Possible applications in biological systems (especially concerning a model of cerebral organization) are briefly discussed. It is understood here, that the system has to display some preliminary dynamical structure before the organizing procedure takes over. What happens afterwards is the subject of this paper.
16 citations
TL;DR: In this article, a grid search method aimed at locating all doubly symmetric orbits of the three-dimensional restricted problems of one, two, etc. is developed and applied numerically on the CDC-3300 computer.
Abstract: A grid search method aimed at locating ‘all’ doubly symmetric orbits of the three-dimensional restricted problems of one, two, etc. revolutions is developed and applied numerically on the CDC-3300 computer. Three new types of orbits have thus been located and a second order ‘predictorcorrector’ method is applied in order to determine a certain number of members of the families of which the ‘located’ orbits are members. The stability of these members is also discussed.
11 citations
TL;DR: In this article, it was proved that the Wigner operator accepts as eigenvalues the differences of the eigen values of two equivalent Schrodinger equations, with the help of a Fourier transform in the phase space.
10 citations
TL;DR: A plot of median grain size against quartile deviation (after Buller and McManus) can be used to distinguish mudflow deposits as discussed by the authors, and a characteristic envelope for poorly sorted streamflow deposits is also defined.
9 citations
TL;DR: In this paper, the main product was 2-methylpropene, and it was found to be formed both directly from 1-bromo-2-methyl-propane, and through isomerization of the latter to 2-mmethylpropane.
TL;DR: In this paper, the input-output decoupling control problem for a generalized multivariable linear model, covering most practical situations, is treated for the case where the model involves disturbances in the parameters.
Abstract: The input-output decoupling control problem for a generalized multivariable linear model, covering most practical situations, is treated for the case where the model involves disturbances in the parameters. A sensitive decoupling controller is derived which maintains the decoupling conditions to first order in the parameter variations, about their nominal values.
TL;DR: In this article, Poincare's continuation method is applied to the elliptic restricted problem for the computation of four families of doubly symmetric three-dimensional periodic orbits emanating from similar orbits corresponding to zero eccentricity.
Abstract: Poincare's continuation method is applied to the elliptic restricted problem for the computation of four families of doubly symmetric three-dimensional periodic orbits emanating from similar orbits corresponding to zero eccentricity The results are given in four tables and the orbits are characterized in regard to their stability
TL;DR: In this paper, the thermodynamic parameters for the adsorption of some representative organic compounds on antimony pentoxide have been determined, and these values were then correlated with some physical properties of the compounds, thus enabling conclusions to be drawn about the nature of the forces responsible for the adorption.
TL;DR: In this article, the first-and second-order eigenvalue/eigenfunction sensitivities to system parameter variations are studied for a class of linear distributed-parameter control systems having a discrete and distinct spectrum.
Abstract: The first-and second-order eigenvalue/eigenfunction sensitivities to system parameter variations are studied for a class of linear distributed-parameter control systems having a discrete and distinct spectrum. An illustrative example is given.
TL;DR: It is shown that in this case it is possible to decouple number of input/output pairs equal to the rank of the decoupling matrix, and partial decoupled procedure is illustrated by means of an example.
Abstract: The decoupling problem is considered for a class of multi-input multi-output time-delay systems, the parameters of which do not satisfy the conditions for total decoupling, i.e. the conditions for decouplin all input/output pairs. It is shown that in this case it is possible to decouple number of input/output pairs equal to the rank of the decoupling matrix. The partial decoupling procedure is illustrated by means of an example.
TL;DR: In this paper, an indirect state-feedback technique for matching a controllable multicontroller system to a given model is presented, where the multicontrollers are transformed to its Asseo phase-variable canonical form prior to the application of the statefeedback control.
Abstract: An indirect state-feedback technique for matching a controllable multicontroller system to a given model is presented. By this technique the multicontroller system is transformed to its Asseo phase-variable canonical form prior to the application of the state-feedback control. The cases where the system under control and the model are equidimensional or not are considered, and a solution to the model-matching problem by using output feedback is provided. The theory is illustrated by three examples.
TL;DR: The synthesis of histidine2-angiotensin II analogues and a new route leading to the synthesis of α-benzyl-l-aspartate, using N-trityl- l- aspartate di-benZyl ester as the starting material, are reported.
Abstract: The synthesis of histidine2-angiotensin II analogues, namely H-Asp-α-(im-Bzl)His-Val-Tyr-Ile-(im-Bzl)His-Pro-Phe-OH and H-Asp-β-(im-Bzl)His-Val-Tyr-Ile-(im-Bzl)His-Pro-Phe-OH, are described. Also a new route leading to the synthesis of α-benzyl-l-aspartate, using N-trityl-l-aspartate di-benzyl ester as the starting material, is reported.
TL;DR: In this paper, the nonlinear behavior of an inductance simulating a gyrator-capacitor circuit is studied and the effect of this nonlinearity in a series tuned circuit, in which the simulated inductance is an element, is the occurrence of jump phenomenon.
Abstract: The nonlinear behaviour of an inductance simulating a gyrator–capacitor circuit is studied. The nonlinearity is the saturation of one of the two operational transconductance amplifiers which are used in the realisation of the gyrator. The effect of this nonlinearity in a series tuned circuit, in which the simulated inductance is an element, is the occurrence of the jump phenomenon. A theoretical study is carried out using the describing-function technique. Experimental results are in good agreement with theory.
TL;DR: The matrizants of periodic solutions in Stormer's problem can be transformed by means of multiplication with constant matrices into symmetric ones as mentioned in this paper, and the six bilinear relations between their elements, existing on account of the symplectic property, are replaced by 14 linear and simple forms.
Abstract: The matrizants of periodic solutions in Stormer's problem, because of their symplectic character, can be transformed by means of multiplication with constant matrices into symmetric ones. As a result the six bilinear relations between their elements, existing on account of the symplectic property, are replaced by 14 linear and simple forms. This fact is very useful in numerical integrations where these relations are used as criteria of accuracy.
01 Jul 1975
TL;DR: In this paper, a correcting state feedback eigenvalue controller is proposed to reduce the sensitivity of the closed-loop eigenvalues to second order in the variations of the open-loop system parameters.
Abstract: A method is presented for designing a correcting state feedback eigenvalue controller, which reduces the sensitivities of the closed-loop eigenvalues to second order in the variations of the open-loop system parameters. An example is worked out to illustrate-the applicability of the method.
TL;DR: In this paper, a method is developed for determining the rate constant of slow diffusion and/or slow adsorption-desorption processes in gas chromatography, which is applied to the desorption of n-butane and trans-butene from an aluminium oxide surface modified with cerium trichloride.
TL;DR: In this article, the motion of a charged particle in a magnetic dipole field was analyzed and the symmetry of the orbits and reflection of the particle was discussed. But the particle motion was restricted to the equatorial plane of the dipole.
Abstract: We analyse the motion of a charged particle in a magnetic dipole field, which provides a basis for discussion, first on the symmetry of the orbits and, second, on the reflection of the particle, as it moves on both sides of the equatorial plane of the dipole
TL;DR: Reference periodic orbits are determined accurately for the planets of the solar system, using a restricted problem model with the Sun and Jupiter as the two primaries as mentioned in this paper, and it is verified that stability of the planetary orbits should imply stability of those reference orbits that are simple-periodic.
Abstract: Reference periodic orbits are determined accurately for the planets of the solar system, using a restricted problem model with the Sun and Jupiter as the two primaries. The prediction is verified that stability of the planetary orbits should imply stability of those reference orbits that are simple-periodic.
TL;DR: In this paper, the expectation of a nonlinear functional F(X) of a Gaussian distributed-parameter process X(x,t) was studied for stochastic nonlinear distributedparameter dynamic systems by functional expansion.
Abstract: Three formulas are given concerning the expectation of a nonlinear functional F(X) of a Gaussian distributed-parameter process X(x,t) . These formulas are useful when studying stochastic nonlinear distributed-parameter dynamic systems by functional expansion.
01 Dec 1975
TL;DR: In this article, the problem of reducing sensitivity to variations of the open-loop system parameters is considered for the case where the objective is to design a feedback controller which drives the openloop eigenvalues to desired positions.
Abstract: The problem of reducing sensitivity to variations of the open-loop system parameters is considered for the case where the objective is to design a feedback controller which drives the open-loop eigenvalues to desired positions. The results are based on the assumption that the open-loop multivariable system is transformed to a phase-variable canonical form prior to the application of the control design procedure.
TL;DR: Il modello elettroforetico delle carbossilesterasi solubili nel corso dell'ontogenesi delMedicago scutellata è stata studiata con elettraforesi orizzontale su gel-amido.
Abstract: Il modello elettroforetico delle carbossilesterasi solubili nel corso dell'ontogenesi delMedicago scutellata e stata studiata con elettroforesi orizzontale su gel-amido. Il modello di ogni organo esaminato include una somma di molteplici forme molecolari di carbossilesterasi, la maggior parte delle quali e sottoposta a considerevoli alterazioni nel corso dell'ontogenesi della pianta.
TL;DR: In this paper, the motion of a system of two deformable (fluid or not) bodies can be reduced to the well-known two-body problem, and the conditions for which the motion can be decomposed into one body and another body.
Abstract: We attempt to derive the conditions for which the motion of a system of two deformable (fluid or not) bodies can be reduced to the well-known two-body problem. The new condition is discussed for some pairs of such bodies existing in the natural world.