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41.
The two-dimensional representation of documents which allows documents to be represented in a two-dimensional Cartesian plane has proved to be a valid visualization tool for Automated Text Categorization (ATC) for understanding the relationships between categories of textual documents, and to help users to visually audit the classifier and identify suspicious training data. This paper analyzes a specific use of this visualization approach in the case of the Naive Bayes (NB) model for text classification and the Binary Independence Model (BIM) for text retrieval. For text categorization, a reformulation of the equation for the decision of classification has to be written in such a way that each coordinate of a document is the sum of two addends: a variable component P(d|ci), and a constant component P(ci), the prior of the category. When plotted in the Cartesian plane according to this formulation, the documents that are constantly shifted along the x-axis and the y-axis can be seen. This effect of shifting is more or less evident according to which NB model, Bernoulli or multinomial, is chosen. For text retrieval, the same reformulation can be applied in the case of the BIM model. The visualization helps to understand the decisions that are taken to order the documents, in particular in the case of relevance feedback. 相似文献
42.
Cinosi A Andriollo N Pepponi G Monticelli D 《Analytical and bioanalytical chemistry》2011,399(2):927-933
A total reflection X-ray fluorescence (TXRF) procedure was developed for the determination of metal traces in petrochemical
end products or intermediates for surfactant synthesis. The method combines a fast and straightforward sample preparation,
i.e. deposition on the sample holder and evaporation of the sample matrix, with an efficient quantification method based on
internal standardization (organic gallium standard). The method developed showed detection limits below 0.05 μg g-1 and in most cases below 0.005 μg g-1. Fifteen elements (Ca, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Rh, Sn, Sr, V and Zn) were determined in matrices such as paraffins,
n-olefins, linear alkylbenzenes, long-chain alkyl alcohols and esters: typical metal contents were below 1 μg g-1. The results were compared with the reference method ASTM D5708 (test method B) based on inductively coupled plasma optical
emission spectroscopy: advantages and drawbacks of the two procedures were critically evaluated. The TXRF method developed
showed comparable precision and absence of bias with respect to the reference method. A comparison of the performances of
the two methods is presented. 相似文献
43.
Carmela Napolitano Manuela Borriello Francesca Cardullo Daniele Donati Alfredo Paio 《合成通讯》2013,43(14):2031-2035
A rapid and efficient synthesis of 1-benzyl-2-difluoromethyl-piperazine is herein described. The new pathway has the advantage of avoiding orthogonal protection at the two piperazine nitrogen atoms; therefore it is suitable for access to several 1-benzyl 2-substituted piperazines starting from the simple commercially available N,N′-dibenzylethylendiamine. 相似文献
44.
Tuccitto N Giamblanco N Ghosh S Spampinato V Labbé P Dumy P Quici S Marletta G Defrancq E Licciardello A 《Langmuir : the ACS journal of surfaces and colloids》2011,27(14):8595-8599
An efficient surface anchoring strategy of tolylterpyridine-tagged DNA single strands (ssDNA-ttpy) synthesized on gold electrodes is reported. The method is based on exchange reactions between Fe(II)bis-terpyridine complexed SAMs and ssDNA-ttpy, and allows efficient hybrydization of the cDNA strands. Moreover, by using low-current focused ion beam lithography, micropatterned arrays are obtained, homogeneously covered with ssDNA-ttpy. The surface adsorption kinetics of ssDNA-ttpy, as well as its hybridization efficiency, was monitored by in situ quartz crystal microbalance with dissipation monitoring (QCM-D) technique. The effective confinement of the ssDNA-ttpy at the micrometer level has been monitored by time of flight secondary ion mass spectrometry (ToF-SIMS) and ellipsometric surface imaging experiments, providing laterally resolved chemical and topographic mapping. 相似文献
45.
Nunzio Motta Pierre D. Szkutnik Massimo Tomellini Anna Sgarlata Massimo Fanfoni Fulvia Patella Adalberto Balzarotti 《Comptes Rendus Physique》2006,7(9-10):1046
Quantum dots (QDs) grown on semiconductors surfaces are actually the main researchers' interest for applications in the forthcoming nanotechnology era. New frontiers in nanodevice technology rely on the precise positioning of the nucleation site and on controlling the shape and size of the dots. In this article we will review some recent studies regarding the control of the nucleation process on semiconductor surfaces. A few approaches to form ordered patterns on surfaces are described: natural patterning induced by surface instabilities (as step bunching or step meandering), in situ substrate patterning by Scanning Tunneling Microscopy (STM), high resolution patterning by Focused Ion Beam (FIB). Growth of epitaxial layers of semiconductors (Ge/Si(100) and InAs/GaAs(100)) on patterned surfaces has been studied by STM or Atomic Force Microscopy (AFM) unveiling the way in which the first atoms start to aggregate and identifying their exact nucleation site. Control of the dot size to match the patterning typical wavelength has been achieved by using surfactants on misoriented substrates. STM images acquired in real time allows one to identify the mechanism of Ge cluster formation on patterned Si(100), and to follow the island transition from pre-pyramid to pyramid. Nucleation of ordered Ge dots on SiO2 substrates has been obtained thanks to FIB tight patterning, achieving island densities of 3.5×1010/cm2. To cite this article: N. Motta et al., C. R. Physique 7 (2006). 相似文献
46.
47.
Nunzio Tuccitto Lara Lobo Agnès Tempez Ivan Delfanti Patrick Chapon Stela Canulescu Nerea Bordel Johann Michler Antonino Licciardello 《Rapid communications in mass spectrometry : RCM》2009,23(5):549-556
We demonstrate the potential of an innovative technique, pulsed radiofrequency glow discharge time‐of‐flight mass spectrometry, for the molecular depth profiling of polymer materials. The technique benefits from the presence, in the afterglow of the pulsed glow discharge, of fragment ions that can be related to the structures of the polymers under study. Thin films of different polymers (PMMA, PET, PAMS, PS) were successfully profiled with retention of molecular information along the profile. Multilayered structures of the above polymers were also profiled, and it was possible to discriminate among layers having similar elemental composition but different polymer structure. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
48.
Paolo Emilio Di Nunzio 《哲学杂志》2018,98(5):388-407
A multi-particle approach of Ostwald ripening in two-phase systems based on direct interactions is developed which successfully explains the stationary right-skewed shape of the particle size distribution found in coarsening experiments of cementite in ferrite at a volume fraction of about 0.07. To reproduce such an evidence the mean field hypothesis of the classical LSW theory has been replaced by a topological framework where any particle exchanges solutes with all its neighbours within an interaction volume proportional to its size. Then, an effective diffusion distance depending on the current average size in the system and on volume fraction of the second phase has been introduced. 相似文献
49.
Auditore A Tuccitto N Marzanni G Quici S Puntoriero F Campagna S Licciardello A 《Chemical communications (Cambridge, England)》2003,(19):2494-2495
Mixed self-assembled monolayers based on thiol-terpyridine and thiophenol molecules on gold surfaces show a tendency to form films whose composition is almost independent of the molar fraction of the components in the starting solution, and this indicates the formation of particularly stable assemblies. 相似文献
50.
Nunzio Cappuccio Diego Lubian 《Annals of the Institute of Statistical Mathematics》2007,59(3):403-423
The purpose of this paper is to investigate the asymptotic null distribution of stationarity and nonstationarity tests when
the distribution of the error term belongs to the normal domain of attraction of a stable law in any finite sample but the
error term is an i.i.d. process with finite variance as . This local-to-finite variance setup is helpful to highlight the behavior of test statistics under the null hypothesis in
the borderline or near borderline cases between finite and infinite variance and to assess the robustness of these test statistics
to small departures from the standard finite variance context. From an empirical point of view, our analysis can be useful
in settings where the (non)-existence of the (second) moments is not clear-cut, such as, for example, in the analysis of financial
time series. A Monte Carlo simulation study is performed to improve our understanding of the practical implications of the
limi theory we develop. The main purpose of the simulation experiment is to assess the size distortion of the unit root and
stationarity tests under investigation. 相似文献