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Wyszukujesz frazę "Fonseca, M." wg kryterium: Autor


Wyświetlanie 1-10 z 10
Tytuł:
On some conjectures regarding tridiagonal matrices
Autorzy:
Fonseca, C. M.
Powiązania:
https://bibliotekanauki.pl/articles/122982.pdf
Data publikacji:
2018
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
tridiagonal matrices
determinant
permanent
Chebyshev polynomials of second kind
macierz trójdiagonalna
wielomiany Czebyszewa
wyznacznik
Opis:
We discuss several conjectures proposed recently by A.Z. Küçük and M. Düz on the permanent of certain type of tridiagonal matrices. We recall some less known results on tridiagonal matrices and, at the same time, bring other results together to a common framework.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2018, 17, 4; 13-17
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Number of P-Vertices of Singular Acyclic Matrices: An Inverse Problem
Autorzy:
Du, Zhibin
da Fonseca, Carlos M.
Powiązania:
https://bibliotekanauki.pl/articles/31804164.pdf
Data publikacji:
2020-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
trees
acyclic matrices
singular
multiplicity of eigenvalues
P-set
P-vertices
Opis:
Let A be a real symmetric matrix. If after we delete a row and a column of the same index, the nullity increases by one, we call that index a P-vertex of A. When A is an n × n singular acyclic matrix, it is known that the maximum number of P-vertices is n − 2. If T is the underlying tree of A, we will show that for any integer number k ∈ {0, 1, . . ., n − 2}, there is a (singular) matrix whose graph is T and with k P-vertices. We will provide illustrative examples.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 2; 525-532
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Shot Peening With Glass Microspheres on the Fatigue Behavior of a Low Carbon Steel
Autorzy:
de Lacerda, J. C.
Pereira, I. R.
Costa, J. M. G.
Pinto, J. S.
Souza, H. F. M.
Fonseca, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/352156.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
fatigue
shot peening
Wöhler curve
low carbon steel
glass microspheres
Opis:
The present work has the objective of studying the effect of shot peening with glass microspheres on SAE 1020 steel in its resistance to fatigue. Fatigue tests were carried out by rotary bending with load control and loading on balance in specimens with and without shot peening. A rotation speed of approximately 750 rpm (12.5 Hz) was employed in the fatigue tests. Vickers microhardness tests were performed in order to verify the surface hardening produced by shot peening with glass microspheres. Analysis of the steel surface and fatigue fractures was performed using scanning electron microscopy (SEM). Fatigue tests were performed in order to obtain S-N curves (Wöhler curves). It was observed that shot peening with glass microspheres improved the fatigue strength of the steel at high cycle.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 4; 1513-1518
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stratigraphy, palynology and organic geochemistry of the Devonian-Mississippian metasedimentary Albergaria-a-Velha Unit (Porto-Tomar shear zone, W Portugal)
Autorzy:
Machado, G.
Francu, E.
Vavrdová, M.
Flores, D.
Fonseca, P. E.
Rocha, F. T.
Pereira, L. C. G.
Gomes, A.
Fonseca, M.
Chaminé, H.
Powiązania:
https://bibliotekanauki.pl/articles/2059150.pdf
Data publikacji:
2011
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Mississippian
Late Devonian
Ossa-Morena Zone
Porto-Tomar shear zone
palynology
organic geochemistry
Opis:
The Albergaria-a-Velha Unit is one of several tectonostratigraphic out-of-sequence units of the metamorphic belt associated with the Porto-Tomar shear zone (Ossa-Morena Zone, W Portugal). It is composed of considerably deformed - very low grade - metasediments, namely shales, siltstones and rare fine sandstones. In this work we present new sedimentological and biostratigraphical data that suggest the Albergaria-a-Velha Unit was deposited from the (?)early Frasnian to the Serpukhovian in a distal marine environment, where turbiditic and basinal sedimentation prevailed. Palynofacies analysis and lithological data point to a gradual increase of terrestrial input, suggesting a prograding system. Detrital framework data is indicative of a stable cratonic sediment source area composed of low grade metamorphic rocks. The timing of the onset of the Porto-Tomar shear zone activity and consequently its influence on the sedimentation of this unit is discussed. Organic petrology and geochemistry data indicate that the Albergaria-a-Velha Unit is within the dry gas window in terms of hydrocarbon generation ranges.
Źródło:
Geological Quarterly; 2011, 55, 2; 139-164
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Styrene oxidation by copper(II) complexes salen-type encapsulated into NaY zeolite
Katalityczne utlenianie styrenu w obecności kompleksów miedzi(II) typu salen osadzonych na zeolicie NaY
Autorzy:
Kuźniarska-Biernacka, I.
Carvalho, M. A.
Correia Neves, I.
Fonseca, A. M.
Lisińska-Czekaj, A.
Czekaj, D.
Powiązania:
https://bibliotekanauki.pl/articles/352679.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
copper(II) complexes
Schiff base
NaY zeolite
kompleksy miedzi(II)
zasada Schiffa
zeolit NaY
Opis:
The copper(II) complex with a Schiff-base salen-type ligand has been encapsulated in the nanopores of a NaY zeolite by using two different methodologies, the flexible ligand and in situ complex preparation methods. The encapsulated and non-encapsulated copper(II) complexes were screened as catalysts for styrene oxidation by using TBHP as the oxygen source in acetonitrile solvent. Under the optimized conditions, the catalysts exhibited moderate activity with higher selectivity to benzaldehyde. Both heterogeneous catalysts were found to be reusable after the catalytic cycle, but with some loss of activity.
Osadzenie kompleksu miedzi(II) z zasadą Schiffa typu salen na zeolicie typu NaY zostało przepowadzone za pomocą dwóch metod „flexible ligand" i „in situ”. Katalityczne właściwości otrzymanego kompleksu oraz jego heterogenizowanych analogów badano w reakcji utleniania styrenu w obecności TBHP. Jako rozpuszczalnik stosowano acetonitryl. Testowane katalizatory wykazują średnią aktywność katalityczną z tendencją wytwarzania aldehy du benzoesowego. Oba heterogenizowane katalizatory mogą być wykorzystywane ponownie bez utraty aktywności katalitycznych.
Źródło:
Archives of Metallurgy and Materials; 2013, 58, 4; 1291-1294
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Styrene epoxidation over heterogeneous manganese (III) complexes
Autorzy:
Kuźniarska-Biernacka, I.
Lisinska-Czekaj, A.
Czekaj, D.
Alves, M. J.
Fonseca, A. M.
Neves, I. C.
Powiązania:
https://bibliotekanauki.pl/articles/958207.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
styrene epoxidation
heterogeneous manganes
Opis:
The manganes (III) complex functionalised with 2,3-dihydropyridazine has been encapsulated in the supercages of the NaY zeolite using two different procedures, flexible ligand and in situ complex. The parent zeolite and the encapsulated manganese (LTI) complexes were screened as catalysts for styrene oxidation by using t-BOOH as the oxygen source in acetonitrile. Under the optimized conditions, the catalysts exhibited moderate activity with high selectivity to benzaldehyde.
Źródło:
Archives of Metallurgy and Materials; 2016, 61, 3; 1477-1482
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Uncovering production flows from small farms: results from Poland and Portugal case studies
Przepływy produkcyjne drobnych gospodarstw rolnych na przykładzie regionów badawczych z Polski i Portugalii
Autorzy:
Czekaj, M.
Hernandez, P.
Fonseca, A.
Rivera, M.
Żmija, K.
Żmija, D.
Powiązania:
https://bibliotekanauki.pl/articles/1790571.pdf
Data publikacji:
2019
Wydawca:
The Polish Association of Agricultural and Agribusiness Economists
Tematy:
small farms
production flows
Portugal
Polska
drobne gospodarstwa rolne
przepływy produkcyjne
Portugalia
Polska
Opis:
This study is an attempt to assess the impact of small farms (SF) on the regional food product circulation of specific key products in selected, fragmented, agrarian regions in Poland and Portugal. The empirical study is based on the analysis of food product maps which were developed based on data from a survey conducted among owners of small farms and small food businesses at focus group meetings and workshops organized in 2017 and 2018 in the Nowotarski and Nowosądecki subregions in Poland and in the Alentejo Central and Oeste subregions in Portugal. Qualitative data analysis was conducted using uniform methodology. In each of the subregions, focus groups helped to confront the assumptions resulting from surveys and corroborate the flows and fluxes described in the developed food product maps. Data collected during focus groups were enriched by data gathered during regional workshops that focused on food system governance. It was concluded that food product maps indicate interesting relationship flows of small farmers’ products along the food system, highlighting the role of fluxes connecting small farmers with other actors regarding specific key products. Several similarities and disparities between regional KP production flows in the Portuguese and Polish subregions, based on the type of key product, the various distribution channels and farming capacities present in each subregion were observed.
Źródło:
Annals of The Polish Association of Agricultural and Agribusiness Economists; 2019, 21, 3; 49-61
2657-781X
2657-7828
Pojawia się w:
Annals of The Polish Association of Agricultural and Agribusiness Economists
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Validation and statistical analysis of the group for high resolution sea surface temperature data in the Arabian Gulf
Autorzy:
Nesterov, O.
Temimi, M.
Fonseca, R.
Nelli, N.R.
Addad, Y.
Bosc, E.
Abida, R.
Powiązania:
https://bibliotekanauki.pl/articles/2078874.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
validation
statistical analysis
sea surface temperature
annual variability
seasonal variability
Arabian Gulf
Oman Sea
Opis:
The combined effect of climate change and steadily increasing seawater demand for industrial and domestic purposes in the Arabian Gulf region has a significant impact on the ecosystem in this region. Additionally, this effect may reduce the efficiency and increase the operating costs of industrial facilities that utilize seawater for cooling and other purposes. In this context, it is important to know various statistical characteristics of the sea surface temperature (SST) and their trends, in addition to the mean climatological characteristics. The analysis conducted in this study utilized a 17-year Group for High Resolution Sea Surface Temperature Level 4 dataset of 0.01 × 0.01° spatial resolution. First, the dataset was compared against a 2-year seawater temperature measurements at the ten offshore buoys in the relatively shallow coastal waters of the United Arab Emirates between Ras Ghumais and Dubai, which showed a reasonably good agreement between the two datasets, with the estimated root mean square deviations ranging from 0.5 to 0.9°C. Subsequently, several statistical SST characteristics were calculated. The trend analysis showed not only positive tendencies in the mean SSTs of up to 0.08°C/year in the northern Gulf, but also the trends in the annual percentile exceedances, particularly the 95th percentiles (near-maximum SSTs), which increased by approximately 0.07°C/year in the western United Arab Emirates and eastern Qatar waters. On the contrary, the 5th percentiles (near-minimum SSTs) decreased by up to 0.1°C/year, especially in the waters around Bahrain, Qatar, and the western United Arab Emirates. These results indicate that extreme hot and cold SST events in the Gulf are becoming more frequent and more extreme than before.
Źródło:
Oceanologia; 2021, 63, 4; 497-515
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Narażenie na nanocząstki w środowisku pracy w procesach ceramicznych wykorzystujących technologię laserową
Workplace exposure to nanoparticles in ceramic processes using laser technology
Autorzy:
Fonseca, A.S.
Viana, M.
Querol, X.
Moreno, N.
De Francisco, I.
Estepa, C.
De La Fuente, G.F.
Powiązania:
https://bibliotekanauki.pl/articles/180101.pdf
Data publikacji:
2016
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
ceramika
pyły
nanocząstki
ablacja laserowa
spiekanie laserowe
pomiary
ceramics
dusts
nanoparticles
laser ablation
laser sintering
measurements
Opis:
W artykule przedstawiono wyniki oryginalnych badań dotyczących narażenia pracowników przemysłu ceramicznego na ultradrobnej nanocząstki, które powstają w trakcie wykorzystywania lasera do spiekania oraz w wyniku ablacji laserowej. Wyniki przeprowadzonych badań porównano z wartościami referencyjnymi, zalecanymi w stosunku do wymienionych cząstek, a także skomentowano poziom narażenia pracowników, który został uwidoczniony eksperymentalnie.
The article presents original research results regarding the exposure of workers employed in the ceramic industry towards ultra small and nanoparticles created as a result of laser sintering as well a laser ablation. The results of the research were compared with the referential values for the abovementioned particles and the experimentally proven level of worker's exposure was awarded a commentary.
Źródło:
Bezpieczeństwo Pracy : nauka i praktyka; 2016, 7; 18-21
0137-7043
Pojawia się w:
Bezpieczeństwo Pracy : nauka i praktyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Seroprevalence of SARS-CoV-2 and assessment of epidemiologic determinants in Portuguese municipal workers
Autorzy:
Barros Ferreira, Nuno
Pereira, Helena
Pereira, Ana M.
Azevedo, Luís F.
Santos, Mariana
Maranhão, Priscila
Correia, Ricardo
Fonseca, João A.
Canedo, Paulo
da Costa Pereira, Altamiro
Sousa-Pinto, Bernardo
Powiązania:
https://bibliotekanauki.pl/articles/2084912.pdf
Data publikacji:
2022-06-08
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
SARS-CoV-2 infection
COVID-19 pandemic
COVID-19 virus
COVID-19 serodiagnosis
COVID-19 antibody testing
SARS-CoV-2 infection serological testing
Opis:
ObjectivesTo assess the seroprevalence of SARS-CoV-2 antibodies in municipal employees of Northern Portugal during the first pandemic wave (May–June 2020) and its association with potentially related risk factors for infection.Material and MethodsThe authors assessed municipal employees of 2 cities in Northern Portugal, in whom serological tests to SARS-CoV-2 and an epidemiological survey were applied. The authors assessed the proportion of individuals presenting IgM and/or IgG antibodies to SARS-CoV-2, and evaluated the association between having positive serological test results, epidemiologic variables and clinical presentations. Reported symptoms were evaluated on their sensitivity, specificity, and predictive values.ResultsThe authors assessed 1696 employees, of whom 22.0% were firefighters, 10.4% were police officers, 10.3% were maintenance workers, and 8.1% were administrative assistants. The seroprevalence of SARS-CoV-2 infection was 2.9% (95% CI: 2.1–3.7%). Administrative assistants comprised the professional group with highest seroprevalence of SARS-CoV-2 (OR = 1.9 in the comparison with other occupational groups, 95% CI: 0.8–4.3, p = 0.126). The seroprevalence of SARS-CoV-2 infection among those who were in direct contact with COVID-19 patients in their professional activity was 3.9%, compared to 2.7% among those who were not in direct contact with such patients (OR = 1.5, 95% CI: 0.8–2.8, p = 0.222). The highest risk of infection was associated with the presence of a confirmed SARS-CoV-2 infection in the household (OR = 17.4, 95% CI: 8.3–36.8, p < 0.001). Living with a healthcare professional was not associated with a higher risk of infection (OR = 1.0, 95% CI: 0.4–2.5, p = 0.934). Anosmia/dysgeusia was the symptom with the highest positive predictive value (52.2%, 95% CI: 31.8–72.6, p < 0.001) and specificity (99.3%, 95% CI: 98.9–99.7, p < 0.001), while cough was the most prevalent symptom among SARS-CoV-2 seropositive participants (36%).ConclusionsThe authors observed a SARS-CoV-2 seroprevalence of 2.9% among assessed municipal employees. Anosmia/dysgeusia was the COVID-19 symptom which displayed the highest positive predictive value and specificity.
Źródło:
International Journal of Occupational Medicine and Environmental Health; 2022, 35, 3; 297-307
1232-1087
1896-494X
Pojawia się w:
International Journal of Occupational Medicine and Environmental Health
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-10 z 10

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