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


Tytuł:
Numerical evaluation of sound attenuation provided by periodic structures
Autorzy:
Martins, M.
Godinho, L.
Picado-Santos, L.
Powiązania:
https://bibliotekanauki.pl/articles/176630.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
traffic noise
sonic crystals
numerical method
Opis:
The use of periodic structures as noise abatement devices has already been the object of considerable research seeking to understand its efficiency and see to what extent they can provide a functional solu- tion in mitigating noise from different sources. The specific case of sonic crystals consisting of different materials has received special attention in studying the influence of different variables on its acoustic performance. The present work seeks to contribute to a better understanding of the behavior of these structures by implementing an approach based on the numerical method of fundamental solutions (MFS) to model the acoustic behavior of two-dimensional sonic crystals. The MFS formulation proposed here is used to evaluate the performance of crystals composed of circular elements, studying the effect of varying dimen- sions and spacing of the crystal elements as well as their acoustic absorption in the sound attenuation provided by the global structure, in what concerns typical traffic noise sources, and establishing some broad indications for the use of those structures.
Źródło:
Archives of Acoustics; 2013, 38, 4; 503-516
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An energy harvesting circuit for self-powered sensors
Autorzy:
Fernandes, J. R.
Martins, M.
Piedade, M.
Goncalves, H.
Powiązania:
https://bibliotekanauki.pl/articles/398011.pdf
Data publikacji:
2011
Wydawca:
Politechnika Łódzka. Wydział Mikroelektroniki i Informatyki
Tematy:
prostownik dwupołówkowy
odzyskiwanie energii
power-harvesting
full-wave rectifier
Opis:
In this work we present a prototype circuit to harvest energy from radio waves or through magnetic coupling based on a stack of full-wave rectifiers with transistors working on sub-threshold region. This circuit will use as an input a field-to-voltage converter capable of outputting a 200mV waveform and is able to self-start without any other energy sources. The circuit presented here is a proof of concept energy-harvesting circuit powering a low frequency ring oscillator which acts as the load. The circuit is designed, simulated and tested in a standard CMOS process, AMS CMOS 0.35 μm.
Źródło:
International Journal of Microelectronics and Computer Science; 2011, 2, 1; 1-5
2080-8755
2353-9607
Pojawia się w:
International Journal of Microelectronics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Traffic splitting in MPLS networks - a hierarchical multicriteria approach
Autorzy:
Craveirinha, J. M. F.
Cli'maco, J. C. N.
Pascoal, M. M. B.
Martins, L. M. R. A.
Powiązania:
https://bibliotekanauki.pl/articles/308582.pdf
Data publikacji:
2007
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
multicriterial optimization
multicriteria shortest paths
routing telecommunication networks
Internet/MPLS
Opis:
In this paper we address a new hierarchical multicriteria routing model associated with a two-path traffic splitting routing method in MPLS networks whereby the bandwidth required by a given node-to-node traffic flow is divided by two disjoint paths. The model has two levels of objective functions and several constraints. An algorithmic approach is presented for calculating non-dominated solutions and selecting good compromise solutions to this problem. Also a number of computational experiments are presented.
Źródło:
Journal of Telecommunications and Information Technology; 2007, 4; 3-10
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A multi-model approach to Saint-Venant equations: A stability study by LMIs
Autorzy:
Dos Santos Martins, V.
Rodrigues, M.
Diagne, M.
Powiązania:
https://bibliotekanauki.pl/articles/330130.pdf
Data publikacji:
2012
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
równanie Saint-Venanta
system nieskończenie wymiarowy
stabilność wykładnicza
Saint-Venant equation
multi-model
LMIs
infinite dimensional system
exponential stability
strongly continuous semigroup
internal model boundary control
Opis:
This paper deals with the stability study of the nonlinear Saint-Venant Partial Differential Equation (PDE). The proposed approach is based on the multi-model concept which takes into account some Linear Time Invariant (LTI) models defined around a set of operating points. This method allows describing the dynamics of this nonlinear system in an infinite dimensional space over a wide operating range. A stability analysis of the nonlinear Saint-Venant PDE is proposed both by using Linear Matrix Inequalities (LMIs) and an Internal Model Boundary Control (IMBC) structure. The method is applied both in simulations and real experiments through a microchannel, illustrating thus the theoretical results developed in the paper.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2012, 22, 3; 539-550
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design of an adaptive fuzzy variable structure compensator for the nonholonomic mobile robot in trajectory tracking task
Autorzy:
Begnini, M.
Bertol, W.
Martins, N. A.
Powiązania:
https://bibliotekanauki.pl/articles/971054.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
nonholonomic mobile robot
trajectory tracking
variable structure control
uncertainties and disturbances
fuzzy compensator
Lyapunov theory
Opis:
A robust adaptive kinematic control strategy, based on the methodology of variable structure control is considered in this paper. Because the dynamics of mobile robots is subject to uncertainties and disturbances, a fuzzy compensator is adopted to estimate them. In order to minimize the tracking errors and to attenuate the chattering phenomenon, an adaptation law for the fuzzy compensator is obtained by Lyapunov stability theory so as to asymptotically stabilize the control system as well as guarantee the convergence of the tracking errors. In terms of comparison with the boundary layer variable structure controller, simulations and experiments verify the feasibility and effectiveness of the proposed kinematic control strategy for the nonholonomic mobile robots under the incidence of uncertainties and disturbances.
Źródło:
Control and Cybernetics; 2018, 47, 3; 239-275
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Antioxidant enzymes activity affects Burkholderia sp. Ni tolerance
Autorzy:
Dourado-Ribeiro, M.
Franco, M.
Martins, P.
Peters, L.
Azevedo, R.
Powiązania:
https://bibliotekanauki.pl/articles/79826.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
conference
antioxidative enzyme
nickel
water contamination
soil contamination
oxidative stress
reactive oxygen species
Burkholderia
bioremediation
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2013, 94, 2
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Integrating coagulation and Fenton’s oxidation for pharmaceutical effluents treatment
Koagulacja połączona z utlenianiem Fentona w oczyszczaniu ścieków farmaceutycznych
Autorzy:
Martins, R. C.
Oliveira, A. C.
Quinta-Ferreira, R. M.
Powiązania:
https://bibliotekanauki.pl/articles/2073214.pdf
Data publikacji:
2015
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
pharmaceutical wastewater
heterogeneous Fenton's process
photo-Fenton process
low cost catalysts
biodegradability
ścieki farmaceutyczne
heterogeniczny proces Fentona
reakcja foto-Fentona
kataliza nisko-kosztowa
biodegradowalność
Opis:
Pharmaceutical industry produces complex and bio-refractory wastewater whose discharge throughout water courses constitutes an environmental danger. Although several works can be found handling with simulated pharmaceutical effluents, data reporting results gathered using actual wastewater is still scarce. This work reveals that Fe-Ce-O and red volcanic rock are interesting catalysts for dark and photo-Fenton. Furthermore, the light/H2O2 system showed interesting results and it is now being explored at the pilot scale by the pharmaceutical industry that provided the effluent.
Przemysł farmaceutyczny wytwarza złożone i bioodporne ścieki, których zrzut zwykła drogą stwarza zagrożenie dla środowiska. Pomimo tego, że kilka prac zajmuje się transportem symulowanych ciekłych odpadów farmaceutycznych, dane dotyczące rzeczywistych ścieków są wciąż skąpe. W prezentowanej pracy stwierdzono, że Fe-Ce-O i czerwona skała wulkaniczna są ciekawymi katalizatorami w reakcji foto-Fentona. Ponadto układ światło/H2O2 wykazał się interesującymi właściwościami i obecnie jest badany w skali pilotowej przy obróbce ścieków w przemyśle farmaceutycznym.
Źródło:
Inżynieria i Aparatura Chemiczna; 2015, 4; 174--177
0368-0827
Pojawia się w:
Inżynieria i Aparatura Chemiczna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Substrate Temperature Influenced Structural and Electrical Behaviour of~RF Magnetron Sputtered $Ag_2Cu_2O_3$ Films
Autorzy:
Sreedhar, A.
Hari Prasad Reddy, M.
Uthanna, S.
Martins, R.
Elangovan, E.
Pierson, J.
Powiązania:
https://bibliotekanauki.pl/articles/1492600.pdf
Data publikacji:
2011-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
71.15.Mb
78.20.Ci
74.25.Gz
Opis:
$Ag_2Cu_2O_3$ films were deposited on glass and silicon substrates by RF magnetron sputtering of metallic equimolar $(Ag_{50}Cu_{50})$ alloy target in $Ar-O_{2}$ mixture at different substrate temperature $(T_{s})$ ranging between 303 and 523 K. The effect of $T_{s}$ on the core level binding energies, structural and electrical properties of the films was systematically studied. The films deposited at room temperature were amorphous. The films deposited at 373 K were polycrystalline and the crystallinity was increased when the $T_{s}$ was increased to 423 K. The films deposited at 423 K and subsequently annealed at 498 K exhibits single phase $Ag_2Cu_2O_3$. In the case of films deposited at higher $T_{s}$ of 523 K, $Ag_2O$ was decomposed into Ag. The electrical resistivity of the films deposited at 303 K was $1.2 \times 10^{-5}$ Ω cm, whereas the films formed at 423 K and subsequently annealed at 498 K showed electrical resistivity of $2.2 \times 10^{-3}$ Ω cm due to improvement in the crystallinity of single phase $Ag_2Cu_2O_3$.
Źródło:
Acta Physica Polonica A; 2011, 120, 6A; A-037-A-039
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical study of Hough technique in surgery of otosclerosis, using the finite element method
Autorzy:
Gentil, F.
Parente, M.
Martins, P.
Santos, C.
Almeida, E.
Ferreira, A.
Natali, R.
Powiązania:
https://bibliotekanauki.pl/articles/307201.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
metoda elementów skończonych
otoskleroza
wycięcie strzemiączka
strzemiączko
finite element method
otosclerosis
stapedectomy
stapedotomy
stapes
Opis:
Purpose: Otosclerosis is a metabolic bone disease of the otic capsule that can cause the stapes fixation, resulting in conductive hearing loss or, in a profound sensorineural deafness threshold. Surgery is one of the possible treatments for the otosclerosis. To repair small focus of otosclerosis in the anterior crus of the stapes, in 1960, Hough suggested the implementation of a technique in which part of the anterior crus is fractured and the stapes turned. As a result, the posterior crus of the stapes is the only connection with the inner ear. In this work, the outcome of Hough’s surgical technique was simulated. Methods: Based on computerized images, a finite element model of middle ear ossicles and tympanic membrane was created, as well as a model where the stapes has changed. The discretization of the tridimensional solid model was made using the ABAQUS software. The mechanical properties used were taken from the literature and adequate boundary conditions were applied. Results: The results obtained with the Hough technique simulation were compared with a representative model of the normal ear, taking into account the displacements obtained on the central part of the stapes footplate and the maximum principal stress in the stapes crus. Conclusions: The results obtained are closer to the normal ear model, therefore Hough technique stands out as a good option to correct small focus of otosclerosis.
Źródło:
Acta of Bioengineering and Biomechanics; 2015, 17, 4; 149-153
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A comparative study on the performance of radiation detectors from the HgI2 crystals grown by different techniques
Autorzy:
Martins, J. F. T.
Costa, F. E.
dos Santos, R. A.
de Mesquita, C. H.
Hamada, M. M.
Powiązania:
https://bibliotekanauki.pl/articles/146916.pdf
Data publikacji:
2012
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
crystal growth
iodide mercury crystal
physical vapor transport (PVT)
radiation detector
semiconductor crystal
Opis:
In this work, the establishment of a technology for HgI2 purification and crystal growth is described, aiming at a future application of this crystal as a room temperature radiation semiconductor detector. Two methods of crystal growth were studied in the development of this work: (1) physical vapor transport (PVT) and (2) saturated solution from dimethylsulphoxide (DMSO) complexes. In order to evaluate the crystals obtained using each of these methods, systematic measurements were carried out for determining the stoichiometry, structure, orientation, surface morphology and impurity of the crystal. The influence of these physicochemical properties of the crystals developed was evaluated in terms of their performance as a radiation detector. The best response to radiation was found for the crystals grown by the PVT technique. Significant improvement in the performance of HgI2 radiation detector was found, purifying the crystal by means of two successive growths by the PVT technique.
Źródło:
Nukleonika; 2012, 57, 4; 555-562
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł

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