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Wyszukujesz frazę "Silva, J. L." wg kryterium: Autor


Tytuł:
Parameter estimation for Weibull distribution with right censored data using EM algorithm
Zastosowanie algorytmu maksymalizacji wartości oczekiwanej do estymacji parametrów rozkładu Weibulla w przypadku danych obciętych prawostronnie
Autorzy:
Ferreira, L. A.
Silva, J. L.
Powiązania:
https://bibliotekanauki.pl/articles/301264.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
algorytm EM
estymacja parametrów
estymator największej wiarygodności
niezawodność
EM algorithm
parameter estimation
maximum likelihood estimate
reliability
Opis:
Metoda największej wiarygodności (MLE) służy do estymacji parametrów modelu statystycznego dla zadanych danych. Metoda ta pozwala na estymację nieznanych parametrów modelu statystycznego. Parametry te otrzymuje się poprzez maksymalizację funkcji wiarygodności rozważanego modelu. Często w praktyce metoda ta może jednak nastręczać trudności związane z wielomodalnością funkcji wiarygodności oraz niemożnością uzyskania jawnych analitycznych rozwiązań równań wiarygodności. Równania takie można jedynie rozwiązywać za pomocą metod numerycznych. Trudności te dobrze ilustruje estymacja parametrów rozkładu Weibulla z wykorzystaniem metody największej wiarygodności wykonywana w oparciu o prawostronnie cenzurowane dane z eksploatacji. Rozwiązanie przedstawione w niniejszej pracy opiera się na zastosowaniu algorytmu maksymalizacji wartości oczekiwanej (EM). Możliwości aplikacyjne proponowanej metodyki badano na przykładzie danych eksploatacyjnych uzyskanych z przedsiębiorstwa petrochemicznego, dotyczących awarii pięciu pomp odśrodkowych.
The maximum-likelihood estimation (MLE) is a method of estimating the parameters of a statistical model for given data. This method allows us to estimate the unknown parameters of a statistical model. These parameters are obtained by maximizing the likelihood function of the model in question. In many practical situations the likelihood function is associated with complex models and the likelihood equation has no explicit analytical solution, it is only possible to have its resolution through numerical methods. The estimation of the parameters of the Weibull distribution by maximum-likelihood method based on information from a historical record with right censored data shows this difficulty. The solution presented in this article entails using the Expectation-Maximization (EM) algorithm. Actual data from the historical record of 5 centrifugal pumps failures of a petrochemical company were analyzed for application of the methodology.
Źródło:
Eksploatacja i Niezawodność; 2017, 19, 2; 310-315
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on the Portuguese building stock and its impacts on energy consumption – an average U-value approach
Autorzy:
Sousa, J.
Bragança, L.
Almeida, M.
Silva, P.
Powiązania:
https://bibliotekanauki.pl/articles/231236.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
zasoby budynków
zasoby energii
zużycie energii
element konstrukcyjny
przenikanie ciepła
współczynnik przenikania ciepła
building stock
energy resources
energy consumption
structural element
heat transfer
heat transfer coefficient
Opis:
The article aims to evaluate the Portuguese building stock energy policies and strategy for energy saving in buildings among the EU members. It was found out the average heat transfer coefficients of the main structural elements of Portuguese Buildings and analyzed the U-values of this elements considering different time periods. The fundamentals of this study were funded by the Agency for Development and Innovation (ADI) and co-financed by the European Regional Development Fund (FEDER) through the Operational Program for Competitiveness Factors (POFC) assigned to the Building Physics and Construction Technology Laboratory with the reference SB Tool SPT_2011_4.
Źródło:
Archives of Civil Engineering; 2013, 59, 4; 523-546
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badania laboratoryjne oraz symulacyjne wychładzania komory testowej
Laboratory and simulation studies of the test chamber cooling
Autorzy:
Belok, J.
Fedorowicz, L.
Nowoświat, A.
Pokorska-Silva, I.
Powiązania:
https://bibliotekanauki.pl/articles/362906.pdf
Data publikacji:
2016
Wydawca:
Instytut Fizyki Budowli Katarzyna i Piotr Klemm
Tematy:
badania symulacyjne
wychładzanie obiektu
walidacja
akumulacyjność cieplna
simulation tests
object cooling
validation
thermal accumulation
Opis:
W artykule przedstawiono wyniki analiz symulacyjnych oraz badań laboratoryjnych określających wychładzanie komory testowej w czasie; z odwołaniem do zagadnień budownictwa energooszczędnego.
The article presents the results of simulation analysis and laboratory studies of the test chamber cooling.
Źródło:
Fizyka Budowli w Teorii i Praktyce; 2016, T. 8, nr 2, 2; 5-8
1734-4891
Pojawia się w:
Fizyka Budowli w Teorii i Praktyce
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis and design of a MOSFET-only wideband balun LNA
Autorzy:
Bastos, I.
Oliveira, L. B.
Goes, J.
Silva, M.
Powiązania:
https://bibliotekanauki.pl/articles/397861.pdf
Data publikacji:
2010
Wydawca:
Politechnika Łódzka. Wydział Mikroelektroniki i Informatyki
Tematy:
tranzystor polowy MOS-tylko obwody
redukcja hałasu
CMOS LNAs
MOSFET-only circuits
noise cancelling
wideband LNA
Opis:
In this paper we present a MOSFET-only implementation of a balun LNA. This LNA is based on the combination of a common-gate and a common-source stage with cancellation of the noise of the common-gate stage. In this circuit, we replace resistors by transistors, to reduce area and cost, and to minimize the effect of process and supply variations and mismatches. In addition, we obtain a higher gain for the same voltage drop. Thus, the LNA gain is optimized and the noise figure (NF) is reduced. We derive equations for the gain, input matching and NF. The performance of this new topology is compared with that of a conventional LNA with resistors. Simulation results with a 130 nm CMOS technology show that we obtain a balun LNA with a peak gain of 20.2 dB (about 2 dB improvement), and a spot NF lower than 2.4 dB. The total power consumption is only 4.8 mW for a bandwidth higher than 6 GHz.
Źródło:
International Journal of Microelectronics and Computer Science; 2010, 1, 3; 241-248
2080-8755
2353-9607
Pojawia się w:
International Journal of Microelectronics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Confronting Institutional Discrimination in a Color-Blind World
Autorzy:
Silva, Eric O.
Gillmann, Christopher J.
Tate, KeyAnna L.
Powiązania:
https://bibliotekanauki.pl/articles/623473.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
Color-Blind Racism
Framing
Laminations
Indian Mascots
Immigration
Opis:
This article builds on the scholarship on color-blind ideology by examining discourse challenging two cases of institutional discrimination (the criminalization of unauthorized immigrants and sports teams’ use of Native American symbolism). Our research questions are first, what general options do anti-racists have for navigating norms of color-blindness in the public sphere? Second, how does context influence how people confront institutional discrimination? Based on an ethnographic content analysis of 165 letters to the editor published in American newspapers, we find that opponents of institutional discrimination have the choice of addressing one of four laminations. In each lamination, authors acknowledge framings of racial discrimination that are unacknowledged in previous ones. In the abstraction lamination, authors do not recognize race and ethnicity. In the pigmentation lamination, authors identify race and ethnicity, but not discrimination. Authors in the discrimination lamination acknowledge the practice is harmful to a particular racial or ethnic group, and the contextualization lamination lends added dimensionality to the discourse. A comparison of the laminations of pro-immigrant and anti-mascot letters demonstrates varying willingness to acknowledge racial discrimination. Namely, the pro-immigrant discourse was more color-blind than anti-mascot criticism. We consider the potential causes of these findings and offer suggestions for future research in the conclusion
Źródło:
Qualitative Sociology Review; 2018, 14, 1; 84-108
1733-8077
Pojawia się w:
Qualitative Sociology Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Simple Localized-Itinerant Model for PrAl$\text{}_{3}$: Crystal Field and Exchange Effects
Autorzy:
Von Ranke, P. J.
Palermo, L.
Da Silva, X. A.
Powiązania:
https://bibliotekanauki.pl/articles/1891680.pdf
Data publikacji:
1991-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Dg
75.30.Cr
Opis:
We present a simple magnetic model for PrAl$\text{}_{3}$. The effects of crystal field are treated using a reduced set of levels and the corresponding wave functions are extracted from the actual crystal field levels of Pr$\text{}^{+3}$ in a hexagonal symmetry. The exchange between 4f- and conduction-electrons are dealt within a molecular field approximation. An analytical magnetic state equation is derived and the magnetic behaviour discussed. The parameters of the model are estimated from a fitting of the inverse susceptibility of PrAl$\text{}_{3}$ given in the literature.
Źródło:
Acta Physica Polonica A; 1991, 80, 4; 583-590
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative simulation study of production scheduling in the hybrid and the parallel flow
Autorzy:
Varela, M. L. R.
Trojanowska, J.
Carmo-Silva, S.
Costa, N. M. L.
Machado, J.
Powiązania:
https://bibliotekanauki.pl/articles/407017.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
approach for supporting manufacturing scheduling decision making
heuristics
hybrid flow shop
parallel flow shops
makespan
Opis:
Scheduling is one of the most important decisions in production control. An approach is proposed for supporting users to solve scheduling problems, by choosing the combination of physical manufacturing system configuration and the material handling system settings. The approach considers two alternative manufacturing scheduling configurations in a two stage product oriented manufacturing system, exploring the hybrid flow shop (HFS) and the parallel flow shop (PFS) environments. For illustrating the application of the proposed approach an industrial case from the automotive components industry is studied. The main aim of this research to compare results of study of production scheduling in the hybrid and the parallel flow, taking into account the makespan minimization criterion. Thus the HFS and the PFS performance is compared and analyzed, mainly in terms of the makespan, as the transportation times vary. The study shows that the performance HFS is clearly better when the work stations’ processing times are unbalanced, either in nature or as a consequence of the addition of transport times just to one of the work station processing time but loses advantage, becoming worse than the performance of the PFS configuration when the work stations’ processing times are balanced, either in nature or as a consequence of the addition of transport times added on the work stations’ processing times. This means that physical layout configurations along with the way transport time are including the work stations’ processing times should be carefully taken into consideration due to its influence on the performance reached by both HFS and PFS configurations.
Źródło:
Management and Production Engineering Review; 2017, 8, 2; 69-80
2080-8208
2082-1344
Pojawia się w:
Management and Production Engineering Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ultra-low-voltage LNA with high gain and low noise figure
Autorzy:
Bastos, I.
Oliveira, L. B.
Oliveira, J. P.
Goes, J.
Silva, M. M.
Powiązania:
https://bibliotekanauki.pl/articles/397785.pdf
Data publikacji:
2013
Wydawca:
Politechnika Łódzka. Wydział Mikroelektroniki i Informatyki
Tematy:
LNA
CMOS
noise cancellation
redukcja szumów
Opis:
We present a balun LNA with noise and distortion cancellation using double feedforward. A common-gate and a common-source stage are combined, and their resistive loads are replaced by transistors biased close to saturation to allows low supply voltage, without gain degradation. The proposed feedforward boosts the LNA gain and reduces the noise figure (NF). Simulation results with a 130 nm CMOS technology show that the gain is up to 24 dB and the NF is below 3.2 dB. The total power dissipation is 2.25 mW, leading to an FoM of 6.4 mW-1 with 0.6 V supply.
Źródło:
International Journal of Microelectronics and Computer Science; 2013, 4, 3; 124-128
2080-8755
2353-9607
Pojawia się w:
International Journal of Microelectronics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selectivity of diphenyl-ether herbicide with postemergence applications in chickpea
Autorzy:
Silva, L.G.B.
Da Silva Araujo, L.
Goncalves, D.J.
Souza Valente, M.
Da Silva, A.R.
Nascimento, W.M.
Ribeiro da Cunha, P.C.
Powiązania:
https://bibliotekanauki.pl/articles/2084719.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Cicer arietinum
diphenyl-ether herbicides
weeds
Opis:
There are few reports in literature about the selectivity of postemergence application of herbicides for the control of eudicotyledon weeds (broadleaf) in chickpea. For this reason, the aim of this study was to investigate the selectivity of diphenyl-ether herbicides in chickpea influenced by the herbicides and application rates. A field experiment was conducted from February to June 2017 in Urutaí, state of Goiás, Brazil. Cultivar BRS Aleppo was used in the experiment. The experiment was set up in a randomized block design with 2 × 3 + 1 factorial arrangement and three replications. The first factor was herbicides (fomesafen and lactofen) with the second factor being herbicide rate (50, 75, and 100% of referenced rate) plus an untreated check as a comparison. The applied rates of herbicides were 250 and 180 g ⋅ ha–1 of fomesafen and lactofen, respectively. The selectivity of herbicides was evaluated according to agronomic characteristics (plant population, height, dry matter, number of pods per plant and 100-grain weight) and yields. Both herbicides, regardless of dosage, were selective in chickpea cultivation, even exhibiting leaf necrosis symptoms with visible injuries below 20% with no effect on yield.
Źródło:
Journal of Plant Protection Research; 2019, 59, 3; 350-354
1427-4345
Pojawia się w:
Journal of Plant Protection Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Relationship Between the Levels of Stress and the Age and Years of Service of Military Firefighters From the Fire Rescue Corps of the Metropolitan Area of the State of Sao Paulo
Autorzy:
de Oliveira, R. S.
de Barros Neto, T. L.
da Silva, A. A.
Grandi, J. L.
Menezes, I. B. S.
Powiązania:
https://bibliotekanauki.pl/articles/89950.pdf
Data publikacji:
2012
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
burnout
professional
age effect
work hours
firefighters
Opis:
Purpose. To verify the relationship between stress indicators and the age and years of service of military firefighters from the fire rescue corps of the metropolitan area of the state of Sao Paulo. Methods. Forty military firefighters with the mean age of 37.9 ± 5.4 years, from the 1st, 2nd and 8th fire brigades of the metropolitan area of Sao Paulo participated in this study. All underwent clinical, physical and psychological evaluations to verify the relationship between the age and years of service with the variables of levels of stress (tension, depression, anger, vigor, fatigue, confusion and total stress) on workdays and on days off. Results. On workdays, the mean scores for tension, depression, fatigue and stress were overall higher compared to those on days off. The older the firefighter, the higher the levels of stress, depression, anger and total stress. The more years of service, the greater the depression and anger. Conclusions. The levels of stress were high on workdays. Chronological age and years of service influenced the increase in the scores of stress.
Źródło:
International Journal of Occupational Safety and Ergonomics; 2012, 18, 4; 579-586
1080-3548
Pojawia się w:
International Journal of Occupational Safety and Ergonomics
Dostawca treści:
Biblioteka Nauki
Artykuł

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