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Wyświetlanie 1-7 z 7
Tytuł:
Earmuff Noise Leakage Measurements and Evaluation
Autorzy:
Gerges, S. N.Y.
Gerges, R. N. C.
Dias, R. A.
Powiązania:
https://bibliotekanauki.pl/articles/178157.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
earmuffs
Opis:
This paper reports the quantitative effect of leakage on the noise attenuation of earmuff hearing protectors. The technology used in this study to measure the noise leakage is considered to be a new contribution to this topic. An array of sensors placed between an earmuff and a dummy human head or flat surface was used to measure the contact area. Areas of no contact are considered as the leakage elements. Eight earmuffs varying from high quality/high cost to low quality/low cost were tested, the leakage areas were measured and the reduction in the noise attenuation due to leakage was calculated.
Źródło:
Archives of Acoustics; 2015, 40, 1; 109-115
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The pustulated temnospondyl revisited - a plagiosternine plagiosaurid from the Lower Triassic of Brasil
Autorzy:
Dias-Da-Silva, S
Milner, A.R.
Powiązania:
https://bibliotekanauki.pl/articles/23465.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
temnospondyl
plagiosternine plagiosaurid
Lower Triassic
Triassic
paleontology
Brazil
plagiosaurid
systematics
morphology
Opis:
A recent contribution published in this journal (Dias−daSilva and Ilha 2009) reported a dermal skull fragment indicating the presence of a putative plagiosauroid temnospondyl in the Lower Triassic Sanga do Cabral Formation of the Paraná Basin, Southern Brazil. The taxonomic assignation of this specimen was necessarily tentative as it was based on circumstantial evidence, specifically the presence of a dense pustular ornamentation over four partial dermal skull bones, consideration of the described taxa known to bear such ornamentation, and the stratigraphic and paleobiogeographic range of such taxa. Therefore, Diasda−Silva and Ilha (2009) could not be totally certain about the plagiosauroid affinities of the new specimen and ascribed it to ?Plagiosauridae. It was particularly difficult to make a precise osteological identification of the specimen and six alternative osteological interpretations were made in comparison to both Gerrothorax and Peltobatrachus (see Dias−da−Silva and Ilha 2009: fig. 2). In spite of the poor taxonomic resolution, the new specimen raised interesting questions regarding the presence of plagiosauroid stereospondyls in western Gondwana, as well as their evolutionary patterns, biostratigraphic and paleobiogeographic implications. After Dias−da−Silva and Ilha's (2009) contribution was published, new data from Damiani et al. (2009) raised the possibility of narrowing down the taxonomic identity of the plagiosauroid from Brazil. Accordingly, this brief report provides a more precise taxonomic assignation for this material.
Źródło:
Acta Palaeontologica Polonica; 2010, 55, 3; 561-563
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Natural versus anthropic causes in variations of sand export from river basins: an example from the Guadiana River Mouth (Southwestern Iberia)
Autorzy:
Dias, J. M. A.
Gonzales, R.
Ferreira, Ó.
Powiązania:
https://bibliotekanauki.pl/articles/1187374.pdf
Data publikacji:
2004
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Guadiana River
sediment transport
estuarine sand bodies
floods
NAO
anthropic influence
Opis:
Flood events in many river basins with highly variable discharge values remove accumulated sediments from the riverbed and estuaries. These sediments are exported to the shelf and the adjacent coastlines. Data for rainfall and river discharge for the Guadiana River basin in southwestern Iberia show a strong link with North Atlantic Oscillation (NAO) index patterns. A negative NAO index usually results in more rainfall, and subsequent flooding in the river basin during winter months. During the second half of the 20th century, the flow regime of the Guadiana River and its tributaries have been increasingly constrained by the construction of dams. The consequences were a reduction of coarse-grained sediment export from the upper river basin to the estuary, and a reduction in the number and type of floods.
Źródło:
Polish Geological Institute Special Papers; 2004, 11; 95-102
1507-9791
Pojawia się w:
Polish Geological Institute Special Papers
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Behavior of temporal parameters of the ground reactive forces for the walking of postmenopausal women
Autorzy:
Sousa, A. L. de
Gabriel, R. E. C. dias
Faria, A. M.
Aragao, F. R.
Moreira, M. H. R.
Powiązania:
https://bibliotekanauki.pl/articles/306799.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
lokomocja
własności temporalne
siła
menopauza
bipedal locomotion
temporal parameters
force platform
ground reactive force
menopause
visceral fat
Opis:
The study aimed to examine the influence of body composition and menopause characteristics on certain temporal parameters of the behavior of vertical and anteroposterior components of ground reactive forces, as well as the vertical and anteroposterior rates on the walking of postmenopausal women. The sample consisted of 67 postmenopausal women, average age 59 years. Body composition was assessed by octapolar bioimpedance and ground reactive force by the Kistler force platform. Vertical loading rate correlated positively with age (r = 0.02) and negatively with weight (r = –0.33). The relationship between the rates of vertical loading and unloading associated positively with menopause time (r = 0.27) but negatively with weight (r = –0.27). Vertical unloading rate showed a negative association with abdominal visceral adiposity (r = –0.27). The relationship between the times of the intermediate and final phases of the support correlated significantly with abdominal visceral adiposity (r = 0.25) and fat mass (r = 0.24). The study suggests that fat mass and abdominal visceral adiposity affect the support time, and increased abdominal visceral adiposity implies a slower pre-suspension phase during the walking of postmenopausal women. Hormone replacement therapy was shown to be an enhancer of steeper vertical loading and anteroposterior unloading and longer time in the double support phase, indicating a greater stability of postmenopausal women when walking.
Źródło:
Acta of Bioengineering and Biomechanics; 2015, 17, 3; 119-127
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Contact detection between convex superquadric surfaces
Detekcja kontaktu pomiędzy wypukłymi powierzchniami kwadratowymi
Autorzy:
Fontes Portal, R. J.
Pereira Dias, J. M.
Gonçalves de Sousa, L. A.
Powiązania:
https://bibliotekanauki.pl/articles/139474.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
detekcja kontaktu
kwadryki
powierzchnie superkwadratowe
optymalizacja
dynamika układów wieloczłonowych
contact detection
superquadrics
optimization
multibody dynamics
Opis:
This paper presents a methodology for contact detection between convex quadric surfaces using its implicit equations. With some small modifications in the equations, one can model superellipsoids, superhyperboloids of one or two sheets and supertoroids. This methodology is to be implemented on a multibody dynamics code, in order to simulate the interpenetration between mechanical systems, particularly, the simulation of collisions with motor vehicles and other road users, such as cars, motorcycles and pedestrians. The contact detection of two bodies is formulated as a convex nonlinear constrained optimization problem that is solved using two methods, an Interior Point method (IP) and a Sequential Quadratic Programming method (SQP), coded in MATLAB and FORTRAN environment, respectively. The objective function to be minimized is the distance between both surfaces. The design constraints are the implicit superquadrics surfaces equations and operations between its normal vectors and the distance itself. The contact points or the points that minimize the distance between the surfaces are the design variables. Computational efficiency can be improved by using Bounding Volumes in contact detection pre-steps. First one approximate the geometry using spheres, and then Oriented Bounding Boxes (OBB). Results show that the optimization technique suits for the accurate contact detection between objects modelled by implicit superquadric equations.
W artykule przedstawiono metodologię wykrywania kontaktu między wypukłymi powierzchniami typu kwadryki (superkwadratowymi) opisanymi równaniami uwikłanymi. Po niewielkich modyfikacjach równań, można modelować uogólnione elipsoidy, hiperboloidy jedno- lub dwupowłokowe oraz toroidy. Opisana metodologia ma być zaimplementowana w programie do symulacji układów wieloczłonowych i służyć do modelowania wzajemnej penetracji układów mechanicznych, w szczególności do symulacji kolizji pojazdów mechanicznych z innymi użytkownikami dróg, takimi jak samochody, motocykle i piesi. Zagadnienie detekcji kontaktu między dwoma ciałami jest formułowane jako wypukły, nieliniowy problem optymalizacyjny z ograniczeniami, który jest rozwiązywany przy użyciu dwu metod: metody punktu wewnętrznego (Interior Point, IP) oraz metody sekwencyjnego programowania kwadratowego (Sequential Quadratic Programming, SQP), dostępnych odpowiednio w środowiskach MATLAB i FORTRAN. Funkcja celu podlegająca minimalizacji jest odległością pomiędzy obiema powierzchniami. Ograniczeniami optymalizacji są uwikłane równania powierzchni drugiego stopnia oraz operacje pomiędzy ich wektorami do nich normalnymi i odległością. Zmiennymi decyzyjnymi są punkty kontaktu lub punkty wyznaczające minimalną odległość pomiędzy powierzchniami. Efektywność obliczeniową można poprawić stosując metodę objętości otaczających (Bounding Volumes) we wstępnych krokach detekcji kontaktu. Najpierw aproksymuje się geometrię ciał za pomocą kul, a następnie zorientowanych prostopadłościanów otaczających (Oriented Bounding Boxes, OBB). Wyniki pokazują, że taka technika optymalizacji zapewnia dokładną detekcję kontaktu pomiędzy obiektami modelowanymi przy użyciu uwikłanych równań powierzchni drugiego stopnia.
Źródło:
Archive of Mechanical Engineering; 2010, LVII, 2; 165-186
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Railway industry roadmap in the state of Santa Catarina, Brazil
Roadmap para a indústria ferroviário do estado de Santa Catarina, Brasil
Autorzy:
Dias, A.
Da Silva, J. C.
Kagueiama, H. H.
Haddad, C. R.
Uriona, M. M.
Lezana, Á. G. R.
Juliatto, D. L.
Powiązania:
https://bibliotekanauki.pl/articles/374823.pdf
Data publikacji:
2015
Wydawca:
Politechnika Śląska. Wydawnictwo Politechniki Śląskiej
Tematy:
technology
roadmapping
rail industry
technologia
mapa drogowa
przemysł kolejowy
branża kolejowa
Opis:
This article aims to identify the main requirements to strengthen the railroad industry in Santa Catarina by using technology roadmapping. The railway industry is composed of carriers, manufacturers, suppliers, operators, logistics, services and education. The survey aimed to provide guidelines for the Federation of the State of Santa Catarina Industry (FIESC) to develop its strategic plan for the next eight years. Based on the survey, the roadmap defined vision, mission, a list of key concepts, drivers and actions for the Federation to support the railway industry development, since this industrial sector is still economically unrepresented when compared to other sectors in Santa Catarina. The survey also pointed out there is a strong expansion program of the railway freight and railway transport for people in Brazil, both in government and private sectors.
Este artigo objetiva identificar os principais requisitos para fortalecer a indústria ferroviária em Santa Catarina (SC), por meio da aplicação do processo de technology roadmapping. A indústria ferroviária é composta por transportadores, fabricantes, fornecedores, operadores de logística, serviços e educação. A pesquisa objetivou fornecer orientações para a Federação das Indústrias de Santa Catarina (FIESC) com a finalidade de desenvolver um plano estratégico para os próximos oito anos. Baseando-se na pesquisa, definiram-se a visão, missão e uma lista de conceitos chaves, drivers e ações para que a FIESC apoiasse o desenvolvimento da indústria ferroviária, uma vez que esta é economicamente pouco representativa em comparação com outras indústrias no estado de SC. A pesquisa apontou que há forte expansão do transporte de cargas e pessoas no Brasil, tanto nos setores governamentais quanto nos setores privados.
Źródło:
Transport Problems; 2015, T. 10, z. spec.; 29-36
1896-0596
2300-861X
Pojawia się w:
Transport Problems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hybrid optimization process applied to tuning of Dynamic Matrix Control: atudy case with DC motor
Autorzy:
Carvalho, D. F. de
Ganzaroli, C. A.
Couto, L. do
Dias, R. N. H. M.
Calixto, W. P.
Powiązania:
https://bibliotekanauki.pl/articles/136171.pdf
Data publikacji:
2017
Wydawca:
EEEIC International Barbara Leonowicz Szabłowska
Tematy:
predictive control
deterministic optimization
heuristic optimization
hybrid optimization
DC motor
Opis:
This paper presents study about Dynamic Matrix Control (DMC) controller applied to speed control of DC motor. DMC controller parameters (prediction horizon, control horizon and damping rate of reference) are obtained through optimization methods employing heuristic, deterministic and hybrid strategies. The use of advanced control technique combined with using of optimization methods aims to achieve highly efficient control, reducing the transient state period and variations in steady state. These methods were applied on a simulation model in order to verify which one provides better control results.
Źródło:
Transactions on Environment and Electrical Engineering; 2017, 2, 2; 24-30
2450-5730
Pojawia się w:
Transactions on Environment and Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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