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Wyszukujesz frazę "Medina, A." wg kryterium: Autor


Wyświetlanie 1-6 z 6
Tytuł:
Effects of spark assist on HCCI combustion
Autorzy:
Hunicz, J.
Gęca, M.
Kordos, P.
Medina, A.
Powiązania:
https://bibliotekanauki.pl/articles/134201.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Naukowe Silników Spalinowych
Tematy:
HCCI
homogeneous charge compression ignition
spark assist
double Wiebe
silnik wysokoprężny o spalaniu homogenicznym
Opis:
HCCI (homogeneous charge compression ignition) combustion is initiated by compression temperature and is independent of spark discharge. However, spark discharge can be applied under certain conditions to achieve hybrid combustion, where combustion by flame propagation is followed by auto-ignition of the unburned mixture. Spark assist can be applied to improve combustion stability at low loads or to reduce pressure rise rates under high load regime. In the current study variable spark ignition timing was applied for stoichiometric HCCI combustion, achieved using negative valve overlap technique. Under investigated conditions increase of nitrogen oxides emissions, due to flame propagation, was not observed. To provide more insight into combustion evolution, double Wiebe function was fitted to experimental heat release rates. It was found that only less than 10% of mixture was burned by flame propagation, even for very advanced spark discharge.
Źródło:
Combustion Engines; 2015, 54, 2; 73-77
2300-9896
2658-1442
Pojawia się w:
Combustion Engines
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Should I stay or should I go? Determinants of evacuation upon flood warning among households in a flood prone area in Bukidnon, Philippines
Autorzy:
Medina, M.A.P.
Moraca, J.M.
Powiązania:
https://bibliotekanauki.pl/articles/11445.pdf
Data publikacji:
2016
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Opis:
To identify factors that influence the decision to evacuate upon flood warning by authorities, a study was conducted in a flood prone area in the province of Bukidnon in the Philippines. A survey of flood victims was conducted in Batangan Village, Valencia City, Bukidnon, Philippines wherein 150 respondents were interviewed. Logistic regression analysis was done to test the socio demographic factors that could influence a family’s decision to either evacuate or stay upon advice by government authorities. College education, presence of children in the home, poverty, and extent of flood experienced were found to significantly influence the decision of the family to evacuate. Based on this information, the study provides recommendations for disaster managers in case of future flood incidence in the area.
Źródło:
International Letters of Natural Sciences; 2016, 50
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ensemble of feature extraction methods to improve the structural damage classification in a wind turbine foundation
Autorzy:
Leon-Medina, Jersson X.
Parés, Núria
Anaya, Maribel
Tibaduiza, Diego A.
Pozo, Francesc
Powiązania:
https://bibliotekanauki.pl/articles/27311417.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
structural health monitoring
wind turbine foundation
damage classification
machine learning
feature extraction
XGBoost
monitorowanie stanu konstrukcji
fundament turbiny wiatrowej
klasyfikacja uszkodzeń
uczenie maszynowe
ekstrakcja cech
Opis:
The condition monitoring of offshore wind power plants is an important topic that remains open. This monitoring aims to lower the maintenance cost of these plants. One of the main components of the wind power plant is the wind turbine foundation. This study describes a data-driven structural damage classification methodology applied in a wind turbine foundation. A vibration response was captured in the structure using an accelerometer network. After arranging the obtained data, a feature vector of 58 008 features was obtained. An ensemble approach of feature extraction methods was applied to obtain a new set of features. Principal Component Analysis (PCA) and Laplacian eigenmaps were used as dimensionality reduction methods, each one separately. The union of these new features is used to create a reduced feature matrix. The reduced feature matrix is used as input to train an Extreme Gradient Boosting (XGBoost) machine learning-based classification model. Four different damage scenarios were applied in the structure. Therefore, considering the healthy structure, there were 5 classes in total that were correctly classified. Five-fold cross validation is used to obtain a final classification accuracy. As a result, 100% of classification accuracy was obtained after applying the developed damage classification methodology in a wind-turbine offshore jacket-type foundation benchmark structure.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2023, 71, 3; art. no. e144606
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Welding Effects on the Mechanical Integrity of a Trip800 Steel: a Comparison of Laser Co2 and Gmaw Processes
Wpływ spawania na integralność mechanicznaą stali Trip800: porównanie spawania laserowego ze spawaniem elektrodą topliwą
Autorzy:
Perez-Medina, G. Y.
Lopez, H. F.
Reyes-Valdes, F. A.
Garza-Gomez, A.
Lopez-Ochoa, L. M.
Powiązania:
https://bibliotekanauki.pl/articles/351511.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
laser
GMAW
retained austenite
color metallography
spawanie elektrodą topliwą
austenit resztkowy
metalografia barwna
Opis:
In this work a strip of a transformation induced plasticity (TRIP) steel was welded using gas metal arc welding (GMAW) and Laser CO2 welding (LBW) processes and the resultant strength and ductility of the welded joints evaluated. It was found that LBW lead to relatively high hardness in the fusion zone, FZ where the resultant microstructure was predominantly martensite. The relative volume fractions of phases developed in the welded regions were quantitatively measured using color metallography combined with X-ray diffraction analyses. It was found that the heat affected zone, HAZ developed the maximum amount of martensite (up to 32%) in the steel welded using LBW besides a mixture of bainite, retained austenite and ferrite phases. In contrast, a relatively low percent of martensite (10.8%) was found in the HAZ when the GMAW process was implemented.
Pas ze stali typu TRIP poddano spawaniu elektrodą topliwą oraz spawaniu laserowemu i oceniono wytrzymałość i plastyczność uzyskanych połączeń spawanych. Stwierdzono, że spawanie laserowe prowadzi do uzyskania stosunkowo wysokiej twardości w strefie łączenia, gdzie powstała mikrostrukturę stanowi głównie martenzyt. Względne udziały objętościowe faz w spawanych obszarach zmierzono ilościowo za pomocą barwnej metalografii w połączeniu z dyfrakcyjną analizą rentgenowską. Stwierdzono, że w przypadku stali spawanej laserowo strefa wpływu ciepła zawiera najwięcej martenzytu (do 32%), a oprócz tego mieszanine bainitu, resztkowego austenitu i ferrytu. Natomiast w strefie wpływu ciepła uzyskanej podczas spawania elektrodą topliwą stwierdzono stosunkowo niską zawartość martenzytu (10,8%).
Źródło:
Archives of Metallurgy and Materials; 2014, 59, 4; 1427-1432
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of curing temperature in the alkali-activated blast-furnace slag paste and their structural influence of porosity
Autorzy:
Medina-Serna, T. J.
Arredondo-Rea, S. P.
Gómez-Soberón, J. M.
Rosas-Casarez, C. A.
Corral-Higuera, R.
Powiązania:
https://bibliotekanauki.pl/articles/103278.pdf
Data publikacji:
2016
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
activation of geopolymers
alternative materials
concrete friendly
curing temperature
maturation of hydration
Opis:
Due to the environmental problem posed by the use of Portland cement as construction material, it becomes necessary the search for supplementary cementitious materials that mitigate the ecological damage caused by it. Because the chemical similarity and the high cementitious powers of the blast furnace slag, it is used in the generation of geopolymers in a cement total replacement. This research focused on the study of the influence of the curing conditions on the final properties of blast furnace slag establishing three variables: no cured process (N-C), cured of controlled temperature of 45°C (CT45-C) and room temperature cure (RT-C); evaluating the mechanical behavior until 28 days of age and the water porosity index. The results show that geopolymers based on blast furnace slag has a behavior similar to hydration maturity of Portland cement and curing process decreases the porosity; On the other hand, applying a controlled temperature generates densest resistant pastes such as the variable CT45-C which reach the highest value of resistance in all curing ages.
Źródło:
Advances in Science and Technology. Research Journal; 2016, 10, 31; 74-79
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

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