16 research outputs found
Library transfer between distinct Laser-Induced Breakdown Spectroscopy systems with shared standards
The mutual incompatibility of distinct spectroscopic systems is among the
most limiting factors in Laser-Induced Breakdown Spectroscopy (LIBS). The cost
related to setting up a new LIBS system is increased, as its extensive
calibration is required. Solving the problem would enable inter-laboratory
reference measurements and shared spectral libraries, which are fundamental for
other spectroscopic techniques. In this work, we study a simplified version of
this challenge where LIBS systems differ only in used spectrometers and
collection optics but share all other parts of the apparatus, and collect
spectra simultaneously from the same plasma plume. Extensive datasets measured
as hyperspectral images of heterogeneous specimens are used to train machine
learning models that can transfer spectra between systems. The transfer is
realized by a pipeline that consists of a variational autoencoder (VAE) and a
fully-connected artificial neural network (ANN). In the first step, we obtain a
latent representation of the spectra which were measured on the Primary system
(by using the VAE). In the second step, we map spectra from the Secondary
system to corresponding locations in the latent space (by the ANN). Finally,
Secondary system spectra are reconstructed from the latent space to the space
of the Primary system. The transfer is evaluated by several figures of merit
(Euclidean and cosine distances, both spatially resolved; k-means clustering of
transferred spectra). The methodology is compared to several baseline
approaches.Comment: 32 pages, 22 figure
Basic nutritional properties of cornelian cherry (Cornus mas L.) cultivars grown in the Czech Republic
The ascorbic acid, total polyphenols, total anthocyanins and mineral content, together with antioxidant activity, was determined in five Czech, two Ukrainian and two Austrian cultivars of cornelian cherry (Cornus mas L.) widely grown in the Czech Republic. Ascorbic acid content varied between 199–433 mg kg−1, total polyphenols between 2174–6143 mg kg−1, and total anthocyanins between 61–253 mg kg−1. All fruits were good sources of major metals (K, Ca, Mg, Fe, and Mn) and trace elements (Cu, Zn, and Cr). The antioxidant activity was determined by EPR and DPPH radical scavenging assay and ranged from 29.5% to 67.2%. There was a linear relationship between antioxidant activity and total polyphenol content. Based on the obtained results, Ekotišnovský, Fruchtal, and Ruzyňský cultivars were recommended for further investigation and breeding programme of cornelian cherry fruit in the Czech Republic
Collocation graphs and networks using #LancsBox:Applications in English and Czech
This article deals with the notion of collocation graphs and lexical networks, which not only represent the visualization of the collocational relationship between linguistic units - these have been traditionally displayed in a tabular form with frequency distributions and association measure values - but also an important analytical method in its own right. We illustrate the use of collocation graphs and networks with two case studies as examples demonstrating the use of this technique in lexicography and discourse analysis. The examples are based on both English and Czech corpora, which we analysed using #LancsBox, a free tool which can build collocation graphs and networks on the fly
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ANN-LIBS analysis of mixture plasmas: detection of xenon
We developed an artificial neural network method for characterising crucial physical plasma parameters (i.e., temperature, electron density) in a fast and precise manner that mitigates common issues arising in evaluation of LIBS spectra.</jats:p