Self-optimizing generalized adaptive notch filters — comparison of three optimization strategies

The paper provides comparison of three different approaches to on-line tuning of generalized adaptive notch filters (GANFs) — the algorithms used for identification/tracking of quasi-periodically varying dynamic systems. Tuning is needed to adjust adaptation gains, which control tracking performance of GANF algorithms, to the unknown and/or time time-varying rate of system nonstationarity. Two out of three compared approaches are classical solutions — the first one incorporates sequential optimization of adaptation gains while the second one is based on the concept of parallel estimation. The main contribution of the paper is that it suggests the third way — it shows that the best results can be achieved when both approaches mentioned above are combined in a judicious way. Such joint sequential/parallel optimization preserves advantages of both treatments: adaptiveness (sequential approach) and robustness to abrupt changes (parallel approach). Additionally the paper shows how, using the concept of surrogate outputs, one can extend the proposed single-frequency algorithm to the multiple frequencies case, without falling into the complexity trap known as the “curse of dimensionality”.     

Learning Detail Transfer based on Geometric Features

The visual richness of computer graphics applications is frequently limited by the difficulty of obtaining high‐quality, detailed 3D models. This paper proposes a method for realistically transferring details (specifically, displacement maps) from existing high‐quality 3D models to simple shapes that may be created with easy‐to‐learn modeling tools. Our key insight is to use metric learning to find a combination of geometric features that successfully predicts detail‐map similarities on the source mesh; we use the learned feature combination to drive the detail transfer. The latter uses a variant of multi‐resolution non‐parametric texture synthesis, augmented by a high‐frequency detail transfer step in texture space. We demonstrate that our technique can successfully transfer details among a variety of shapes including furniture and clothing.     

Rational Interpolation from Stochastic Data: A New Froissart's Phenomenon

The analytic structure of Rational Interpolants (R.I.) f (z) built from randomly perturbed data is explored; the interpolation nodes x _j , j = 1,...,M, are real points where the function f reaches these prescribed data . It is assumed that the data are randomly perturbed values of a rational function _(n) ^(m) (m / n is the degree of the numerator/denominator). Much attention is paid to the R.I. familyf _(n+1) ^(m–1), in the small stochasticity régime. The main result is that the additional zero and pole are located nearby the root of the same random polynomial, called the Froissart Polynomial (F.P.). With gaussian hypothesis on the noise, the random real root of F.P. is distributed according to a Cauchy-Lorentz law, with parameters such that the integrated probability over the interpolation interval x ₁, x _M is always larger than 1/2; in two cases studied in detail, it reaches 2/3 in one case and almost 3/4 in the other. For the families f _(n+k) ^(m+k), numerical explorations point to similar phenomena; inspection shows that, in the mean, the localization occurs in the complex and/or real vicinity of the interpolation interval.     

Large-scale multimedia content delivery over optical networks for interactive TV services

iTVP is a system built for delivery of live TV programming, video-on-demand and audio-on-demand with interactive access over IP networks. It has a nationwide range and is designed to provide service to a high number of concurrent users. Hence, scalability is one of the most important issues. In this paper we described how scalability is achieved in a two-level hierarchical architecture of the delivery system. We present the principles of content caching mechanisms and the management of the resulting distributed content repository. The system is implemented and currently operates in a test installation. Although the range of the test system operations is limited, as far as the number of users and the size of the content repository is concerned, the experience gained with iTVP so far provides an insight into the expected prototype performance. We present a system performance evaluation and describe the experience gained during the iGrid demonstration.     

Non-minimum-phase property of N-trailer kinematics resulting from off-axle interconnections

Off-axle interconnections between segments of N-trailer vehicles may imply specific oscillatory behaviour of trailers during vehicle manoeuvres. The paper reveals that this kind of oscillations is a direct consequence of the non-minimum-phase property of vehicle kinematics resulting from application of off-axle interconnections between vehicle segments. First we show the non-minimum-phase property for dynamics of a single pair of interconnected segments, and then how it propagates along the N-trailers equipped with arbitrary number of off-axle interconnections. By referring to available results for linear systems, we locally analyse linearly approximated vehicle kinematics around selected steady-motion conditions. We focus on the time-response effects like undershooting, zero-crossing, and overshooting caused by off-axle interconnections. We show how the number and type of interconnections influence the non-minimum-phase effects. Numerical results obtained for three-trailer kinematics validate theoretical considerations providing some quantitative view of the problem. Short discussion has been provided on the possible control-level consequences resulting from the non-minimum-phase property of N-trailers.     

Iris-based human identity recognition with machine learning methods and discrete fast Fourier transform

Innovations in Systems and Software Engineering - One of the most important modules of computer systems is the one that is responsible for user safety. It was proven that simple passwords and...     

A compositional Petri net translation of general π-calculus terms

We propose a finite structural translation of possibly recursive π-calculus terms into Petri nets. This is achieved by using high-level nets together with an equivalence on markings in order to model entering into recursive calls, which do not need to be guarded. We view a computing system as consisting of a main program (π-calculus term) together with procedure declarations (recursive definitions of π-calculus identifiers). The control structure of these components is represented using disjoint high-level Petri nets, one for the main program and one for each of the procedure declarations. The program is executed once, while each procedure can be invoked several times (even concurrently), each such invocation being uniquely identified by structured tokens which correspond to the sequence of recursive calls along the execution path leading to that invocation.     

Inverse Analysis of Axisymmetrical Compression of HSLA Steel

The objective of the present work is to further explore the problem of selection of the flow stress function which will give the best agreement with experiments for a wide range of the Zener‐Hollomon parameter. Analysis of various flow stress functions was performed, with particular emphasis on the Zerilli‐Armstrong model. Inverse analysis was successfully applied to identify the flow stress model for microalloyed steels deformed in ferrite, two‐phase and austenite regions. Inverse method is applied to interpret the results of the axisymmetrical compression tests performed for HSLA steel samples on a Gleeble 3800 and Split Hopkinson Pressure Bar. Sensitivity analysis is performed based on local and global methods. The objective of the sensitivity analysis in the present study is the evaluation to what extent the selected coefficients in the rheological model influence the result of simulations. In the considered tests this result is represented by two dependent variables, the load and the shape of the sample (barrelling). It is confirmed that the Zerilli‐Armstrong equations should be applied at very high strain rates. Physical meaning is an advantage of this model. Difficulties with identification are the main disadvantage.