Application of Approximated Modal Analysis Methods for PLC System Design

In this paper recent developments rela ted to the analysis of electromagnetic waves propagation by means of modal analysis in H. V. transmission lines are presented. The developments showed here are concerned with the computation of the earth-return path impedance, pro posed earlier by Dubanton {1}, as well as the inclusion of the earth-wires in the impedance matrix. Three phase lines in horizontal and delta configuration (i.e. with centre-phase symmetry) are commonly used in H. V. and E. H. V. transmission. These lines are prone to modal cancellation phenomena. Formulae have been developed by Wedepohl for the calculation of their propagation constants and modal quantities. These formulae greatly simplify the computation of EM waves propagation. The graphical method proposed by Senn and Morf {2} and its application to assess coupling alternatives are discussed. This method is also used by the authors to evaluate non-conventional coupling arrangements.     

An A Contrario Decision Method for Shape Element Recognition

Shape recognition is the field of computer vision which addresses the problem of finding out whether a query shape lies or not in a shape database, up to a certain invariance. Most shape recognition methods simply sort shapes from the database along some (dis-)similarity measure to the query shape. Their main weakness is the decision stage, which should aim at giving a clear-cut answer to the question: “do these two shapes look alike?” In this article, the proposed solution consists in bounding the number of false correspondences of the query shape among the database shapes, ensuring that the obtained matches are not likely to occur “by chance”. As an application, one can decide with a parameterless method whether any two digital images share some shapes or not.     

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Assessment of cell damage in high-pressure-shift frozen broccoli: comparison with market samples

Pressure-shift freezing (PSF) is one of the most promising methods for obtaining high-quality frozen products. The aim of this work was to analyse the differences between broccoli that was frozen using two different PSF processes. In one of the processes, all the freezing was done inside the high-pressure vessel tempered at −20.5 °C. In the other process, the sample was taken out of the vessel after expansion, and freezing was completed using liquid N₂. Colour, texture, electrical conductivity, microstructure and drip losses after centrifugation were analysed and a sensory test was performed. The results were compared with those for conventionally frozen broccoli purchased at the market. PSF broccoli presented less cell damage, lower drip losses and better texture than the market samples. The two different PSF processes assayed produced no significant differences in the final quality of the samples.     

Effects of trial order on contingency judgments: A comparison of associative and probabilistic contrast accounts.

Four experiments examined trial sequencing effects in human contingency judgment. In Experiments 1–3, ratings of contingency between a target cue and outcome were affected by the presentation order of a series of trials distributed in 2 distinct blocks and showed a recency bias. Experiment 4 replicated this effect when the trials were partly intermixed. These recency effects are predicted by an associative learning model that computes associative strengths trial by trial and incorporates configural coding of cues but are problematic for probabilistic contrast accounts, which currently have no provision in the contingency computation for the differential weighting of trials as a function of their order of presentation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Methodological principles of T wave alternans analysis: a unified framework

Visible T wave alternans (TWA) in the electrocardiogram (ECG) had been regarded as an infrequent phenomenon during the first 80 years of electrocardiography. Nevertheless, computerized analysis changed this perception. In the last two decades, a variety of techniques for automatic TWA analysis have been proposed. These techniques have allowed researchers to detect nonvisible TWA in a wide variety of clinical and experimental conditions. Such studies have recently shown that TWA is related to cardiac instability and increased arrhythmogenicity. Comparison of TWA analysis methods is a difficult task due to the diversity of approaches. In this paper, we propose a unified framework which holds the existing methods. In the light of this framework, the methodological principles of the published TWA analysis schemes are compared and discussed. This framework may have an important role to develop new approaches to this problem.     

Directional light scanning laser ophthalmoscope

The cone photoreceptor mosaic of the living human eye has in a limited number of cases been imaged without the use of wavefront-correction techniques. To accomplish this, the directionality of the photoreceptors, as manifested by their waveguiding properties, may be used to advantage. In the present paper we provide a model of our recently proposed directional light scanning laser ophthalmoscope [Opt. Lett. 29, 968 (2004)] together with a detailed numerical analysis of the device. The outcome is compared with experimental results.     

Enthalpy transfer between PWR fuel assemblies in analysis by the lumped subchannel model

Assessment is made of the error in enthalpy predictions in PWR cores resulting from various assumptions in the size of homogenized calculation regions. A coefficient is developed from the differential conservation equations and numerically determined to minimize these errors. It was found that these errors are only of significance for regions comprising three to seven subchannels, region sizes which may be employed in coupled neutronic-thermal hydraulic calculations. A correlation for coefficient values for a range of PWR conditions is presented.     

Fractal Extra-Framework Species in De-aluminated LaY Zeolites and Their Catalytic Activity

Lanthanum-containing Y (LaY) zeolites were prepared by ionic exchange from NaY parent zeolite. The LaY zeolites were de-aluminated by steaming. De-aluminated zeolites presented different Si/Al ratio. The physicochemical properties of these catalysts were characterized by X-ray diffraction, pyridine and xenon adsorption, infrared spectroscopy and ²⁹Si, ²⁷Al, ¹²⁹Xe, ¹³⁹La solid-state nuclear magnetic resonance spectroscopy. Furthermore, a fractal geometry approach was adopted to describe the evolution in the texture as a consequence of de-alumination. The catalytic properties of materials were evaluated in the n-hexane cracking reaction. The catalyst with the highest catalytic activity was the zeolite highest de-aluminated (Si/Al ratio of 3.7). Such performance was attributed on the one hand, to active extra-framework aluminum species hosted in the large cavities of zeolites and, on the other hand to redistribution of lanthanum species into the zeolite as a consequence of de-alumination.