Presentation‐Oriented Key‐Frames Coding Based on Fractals

This paper focuses on the problem of key‐frames coding and proposes a new promising approach based on the use of fractals. The summary, made of a set of key‐frames selected from a full‐length video sequence, is coded by using a 3D fractal scheme. This allows the video presentation tool to expand the video sequence in a “natural” way by using the property of the fractals to reproduce the signal at several resolutions. This feature represents an important novelty of this work with respect to the alternative approaches, which mainly focus on the compression ratio without taking into account the presentation aspect of the video summary. In devising the coding scheme, we have taken care of the computational complexity inherent in fractal coding. Accordingly, the key‐frames are first wavelet transformed, and the fractal coding is then applied to each subband to reduce the search range. Experimental results show the effectiveness of the proposed approach.     

Fully Stressed Piles and Beams in a Winkler’s Medium,End-loaded by an Orthogonal Force,and with Optimum Length

A simplified method of designing fully stressed piles and beams with optimum length in a Winkler’s medium,end-loaded by an orthogonal force and without any point constraint,is proposed. A numerical algorithm distributing the mass by means of the Fully Stressed Design ( FSD) method and updating the moment by finite elements has been first implemented. The use of the FSD method is in general quite simple,and allows to obtain optimum,or close to the optimum,solutions. After having distributed the mass through ...     

Induction Motor Identification by a Microcomputer-Based Structure

The paper deals with the parameter estimation of an induction motor performed through a microcomputer-based data acquisition system and recursive identification algorithms (RLS and RGLS) implemented by means of a general purpose computer. The microcomputer-based data acquisition system is essentially made by connecting the Z80 CPU with its peripherals and auxiliary memories through a bus standard. The motor is represented by a classical fifth-order model linearized around a usual working point; an approximate third-order model, obtained via balanced realization, is in good correlation with the original one according to the identification aims and to the measurement set efficiency. An original CAD procedure is utilized to determine the electrical parameters.     

Advanced testing procedures for high performance coatings

In the first part of this work, an integrated approach incorporating electrochemical (electrochemical impedance spectroscopy), calorimetric (differential scanning calorimetry), mechanical (dynamic mechanical thermal analysis), and infrared spectroscopy (Fourier transform infrared spectroscopy) techniques was used to characterize some organic coatings from the automotive industry. Comparison of the results obtained with different techniques allows not only a higher precision in the evaluation of natural or artificial degradation, which is very difficult to obtain using traditional techniques, but also better data interpretation and, therefore, the possibility of understanding the different degradation mechanisms. In the second part, some preliminary results concerning the comparison of salt spray exposure and EIS measurements are discussed. The statistical analysis of the results showed that the degradation mechanism in the two cases is completely different and, therefore, the information which is obtained with the two testing approaches is also different. With EIS measurements obtained in immersion, it is possible to monitor, in particular, the barrier properties of the coatings, which are dominated by the presence of defects. In the case of salt spray (without scratch), the main property to be measured is the loss of adhesion which causes blister formation. Presented at the 77th Annual Meeting of the Federation of Societies for Coatings Technology, on October 18–22, 1999, in Dallas, TX. Dept. of Materials Engineering, Via Mesiano 77, Trento, Italy. e-mail: Flavio.Deflorian@ing.unitn.it; Stefano.Rossi@ing.unitn.it; Bonora@ing.unitn.it. Dept. ICMMPM, Via Eudossiana, Rome, Italy. e-mail: Lorenzo.Fedrizzi@ing.unitn.it.     

Pathogenic Mutations Shift the Equilibria of α‐Synuclein Single Molecules towards Structured Conformers

α‐synuclein (α‐Syn) is an abundant brain protein whose mutations have been linked to early‐onset Parkinson's disease (PD). We recently demonstrated, by means of a single‐molecule force spectroscopy (SMFS) methodology, that the conformational equilibrium of monomeric wild‐type (WT) α‐Syn shifts toward β‐containing structures in several unrelated conditions linked to PD pathogenicity. Herein, we follow the same methodology previously employed for WT α‐Syn to characterize the conformational heterogeneity of pathological α‐Syn mutants A30P, A53T, and E46K. Contrary to the bulk ensemble‐averaged spectroscopies so far employed to this end by different authors, our single‐molecule methodology monitored marked differences in the conformational behaviors of the mutants with respect to the WT sequence. We found that all the mutants have a much higher propensity than the WT to adopt a monomeric compact conformation that is compatible with the acquiring of β structure. Mutants A30P and A53T show a similar conformational equilibrium that is significantly different from that of E46K. Another class of conformations, stabilized by mechanically weak interactions (MWI), shows a higher variety in the mutants than in the WT protein. In the A30P mutant these interactions are relatively stronger, and therefore the corresponding conformations are possibly more structured. The more structured and globular conformations of the mutants can explain their higher propensity to aggregate with respect to the WT.     

On the non-linear Maxwell–Cattaneo equation with non-constant diffusivity: Shock and discontinuity waves

A numerical study on a non-linear hyperbolic diffusion equation is proposed. The Hartree hybrid method combining finite difference techniques with the method of characteristics is used in the presence of discontinuities between initial and boundary conditions. The technique proved to be an useful tool to overcome oscillation problems and spurious solutions in case of strong non-linearities related to both attractive or repulsive interactions between diffusing species. Two different expressions for the diffusion coefficient are used in order to compare our results with the ones obtained in previous studies relying upon the Laplace transform technique and the MacCormack predictor–corrector method. Finally, an analytic approach based on the singular surface theory is proposed to motivate the numerical results and to clarify some controversial aspects concerning the penetration depth of a diffusive front in the presence of interactions.     

Identification of concrete fracture parameters through size effect experiments

This paper deals with the identification of concrete fracture parameters through indirect methods based on size effect experiments. These methods utilize the size effect curve (structural strength versus structural size), associated with a certain specimen geometry, to identify the tensile strength and the initial fracture energy. These two parameters, in turn, are typically used to characterize the peak and the initial post-peak slope of the cohesive crack law. In the literature, two different approaches can be found for the calculation of the size effect curve: (a) an approach based on the polynomial interpolation of numerically calculated structural strengths of geometrically similar specimens of different sizes, and (b) the classical approach based on equivalent elastic fracture mechanics, which gives rise to the well-known Bažant’s size effect law (SEL). In this paper, the two approaches are first reviewed, the relationship between them is investigated, and a new procedure to identify the tensile strength using the SEL is proposed. Then several sets of experimental results, recently performed at the Politecnico di Milano, are analyzed with both approaches in order to assess their range of applicability and accuracy in the identification of the two fracture parameters specified above.     

Estimation of rheological properties of gelato by FT-NIR spectroscopy

The control of gelato powder mixture production usually is carried out evaluating the gelato liquid phase. The rheological measurements from the present study were conduced on gelato unfrozen liquid phase in order to indirectly evaluate its rheological properties by FT-NIR spectroscopy applied on gelato powders. The calibration set was composed by samples obtained from different recipes having increasing percentage of thickeners, maintaining the proportions of the others compounds constant. After the NIR acquisitions the powders were mixed with warm milk, blended and than settled in order to obtain the unfrozen liquid phase needed for the rheological measurements. For each of the 60 tested recipes three batches with the same thickeners concentration were prepared. The flow curves were obtained with a rotational viscosimeter and were evaluated by using the Ostwald de Waele’s equation and the goodness of fit was evaluated by the R², which was above 0.95. Predictive models of rheological parameters were set up by means of PLS regressions in order to predict the apparent viscosity (η), the consistency coefficient (K) and the flow behaviour index (n) from spectral acquisitions. A high correlation of calibration was found between NIR spectra and apparent viscosity with R² of 0.943. A good correlation was also found between the NIR spectra and the consistency coefficient (K) and flow behaviour index (n), with a determination coefficient (R²) of 0.895 and 0.874, respectively.The good prediction of the models encourages applying them to reduce significantly the time of the powder mixing control during production.     

- : an executable specification language for solving all problems in NP

In this paper a logic-based specification language, called - , is presented. The language is obtained by extending through allowing a limited use of some second-order predicates of predefined form. - programs specify solutions to problems in a very abstract and concise way, and are executable. In the present prototype they are compiled to code, which is run to construct outputs. Second-order predicates of suitable form allow to limit the size of search spaces in order to obtain reasonably efficient construction of problem solutions. - expressive power is precisely characterized as to express exactly the problems in the class NP. The specification of several combinatorial problems in - is shown, and the efficiency of the generated programs is evaluated.