Search results for "Length"
showing 10 items of 2188 documents
On the measurement of bubble size distribution in gas–liquid contactors via light sheet and image analysis
2010
Abstract Particle image velocimetry techniques coupled with advanced image processing tools are receiving an increasing interest for measuring flow quantities and local bubble-size distributions in gas–liquid mechanically agitated vessels. When trying to analyze image information the problem arises that bubble sizes are generally underestimated, due to the fact that the laser sheet used for lighting the system randomly cuts bubbles over non-diametrical planes, leading to an apparent bubble size distribution even in the ideal case of single sized bubbles. Clearly in the case of bubbles with a size distribution the experimental information obtained is affected by the superposition of effects.…
H-point standard additions method for resolution of overlapped chromatographic peaks with a conventional fluorescence detector. Determination of phen…
1996
The H-Point Standard Additions Method (HPSAM) is proposed in order to resolve overlapping peaks in liquid chromatography by using a conventional fluorescence detector. The method uses as analytical signals the heights or the areas obtained at two previously selected emission wavelengths, and good results are obtained for highly overlapping peaks with highly overlapping fluorescence spectra. The principal benefits of the method are the ease of finding the required wavelengths, its insensitivity to changes in the retention time of the peak from one injection to another, and the possibility of using it in highly or only partially overlapping peaks. We have applied the method to the determinati…
Investigations of Chl a aggregates cross-linked by dioxane in 3-methylpentane
1997
In this work, dioxane-bound aggregates of chlorophyll a are prepared in 3-methylpentane. The properties of the aggregates are studied by using steady-state and time-resolved spectroscopies. The Q -region absorption spectrum of the y chlorophyll a-dioxane aggregate shows four clearly resolvable narrow bands with comparable intensities. The band maxima are located at 683, 689, 698 and 702 nm. The emission spectrum consists of two emission bands centred at 699 and 702 nm suggesting the presence of two types of aggregates. High degree of fluorescence polarization is detected yielding the angles between the absorption transition moments with respect to the 702 nm emission transition moment. The …
Magnesium alloys (WE43 and ZE41) characterisation for laser applications
2004
International audience; One of the most important parameters in laser treatment is the quantity of beam energy absorbed by the substrate. Despite its important role played in laser processes, this factor is rarely available for the laser sources wavelengths and at high temperatures reached during such treatments. A series of experiments were carried out in order to characterise, from this point of view, two types of magnesium alloys, WE43 and ZE41, often used in laser applications (cladding, alloying, welding, etc.). The results represent an important step in order to understand Mg-alloys behaviour under laser beam action.
Bayesian versus data driven model selection for microarray data
2014
Clustering is one of the most well known activities in scientific investigation and the object of research in many disciplines, ranging from Statistics to Computer Science. In this beautiful area, one of the most difficult challenges is a particular instance of the model selection problem, i.e., the identification of the correct number of clusters in a dataset. In what follows, for ease of reference, we refer to that instance still as model selection. It is an important part of any statistical analysis. The techniques used for solving it are mainly either Bayesian or data-driven, and are both based on internal knowledge. That is, they use information obtained by processing the input data. A…
From connected pathway flow to ganglion dynamics
2015
During imbibition, initially connected oil is displaced until it is trapped as immobile clusters. While initial and final states have been well described before, here we image the dynamic transient process in a sandstone rock using fast synchrotron-based X-ray computed microtomography. Wetting film swelling and subsequent snap off, at unusually high saturation, decreases nonwetting phase connectivity, which leads to nonwetting phase fragmentation into mobile ganglia, i.e., ganglion dynamics regime. We find that in addition to pressure-driven connected pathway flow, mass transfer in the oil phase also occurs by a sequence of correlated breakup and coalescence processes. For example, meniscus…
Spatial information transmission using orthogonal mutual coherence coding.
2005
We use the coherence of a light beam to encode spatial information. We apply this principle to obtain spatial superresolution in a limited aperture system. The method is based on shaping the mutual intensity function of the illumination beam in a set of orthogonal distributions, each one carrying the information for a different frequency bandpass or spatial region of the input object. The coherence coding is analogous to time multiplexing but with multiplexing time slots that are given by the coherence time of the illumination beam. Most images are static during times much longer than this coherence time, and thus the increase of resolution in our system is obtained without any noticeable c…
AX-PET: Concept, proof of principle and first results with phantoms
2010
AX-PET is a novel PET concept based on long crystals axially arranged and orthogonal Wavelength shifter (WLS) strips, both individually readout by Geiger-mode Avalanche Photo Diodes (G-APD). Its design was conceived in order to reduce the parallax error and simultaneously improve spatial resolution and sensitivity. The assessment of the AX-PET concept and potential was carried out through a set of measurements comprising individual module characterizations and scans in coincidence mode of point-like and extended sources. The estimated energy and spatial resolutions from point-like measurements are R FWHM =11.6% (at 511 keV) and 1.7–1.9 mm (FWHM) respectively as measured with point-like sour…
Some Numerical Invariants of Multilinear Identities
2017
We consider non-necessarily associative algebras over a field of characteristic zero and their polynomial identities. Here we describe most of the results obtained in recent years on two numerical sequences that can be attached to the multilinear identities satisfied by an algebra: the sequence of codimensions and the sequence of colengths.
Varieties of algebras with pseudoinvolution: Codimensions, cocharacters and colengths
2022
Abstract Let A be a finitely generated superalgebra with pseudoinvolution ⁎ over an algebraically closed field F of characteristic zero. In this paper we develop a theory of polynomial identities for this kind of algebras . In particular, we shall consider three sequences that can be attached to Id ⁎ ( A ) , the T 2 ⁎ -ideal of identities of A: the sequence of ⁎-codimensions c n ⁎ ( A ) , the sequence of ⁎-cocharacter χ 〈 n 〉 ⁎ ( A ) and the ⁎-colength sequence l n ⁎ ( A ) . Our purpose is threefold. First we shall prove that the ⁎-codimension sequence is eventually non-decreasing, i.e., c n ⁎ ( A ) ≤ c n + 1 ⁎ ( A ) , for n large enough. Secondly, we study superalgebras with pseudoinvoluti…