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Mechanical characterisation of TiN/ZrN multi-layered coatings

Tavares, C. J.; Rebouta, L.; Andritschky, M.; Ramos, S.
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
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Ultra-microhardness, adhesion and residual-stress analysis tests were performed on reactive sputtered deposited TiN/ZrN multi-layers. Hardness values as high as ~3600 Vickers were achieved for this material. Scratch tests of coatings deposited on steel substrates confirmed the existence of different mechanisms associated with total adhesion failure, depending essentially on multi-layer deposition control parameters. Stress-relaxation measurements indicated the compressive nature of these thin films. The inherent mechanical characterisation was broadened regarding the induced contributions from film thickness, total interfacial roughness, number of bi-layers and corresponding modulation periodicity. Complementary analyses with data extracted from structural XRD studies have been undertaken.; http://www.sciencedirect.com/science/article/B6TGJ-41M9FXX-14/1/f67cd4e602801eb3439973eebbef7433

Caracterização microestrutural e eletroquímica de revestimentos ambientalmente amigáveis aplicados sobre a liga de Al 2024-T3.; Microestructural and electrochemical characterization of environmentally friendly coatings applied on Al alloy 2024-T3.

Morales Palomino, Luis Enrique
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 14/11/2007 PT
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A crescente preocupação com o desenvolvimento sustentável, aliada com uma maior conscientização com relação à preservação do meio ambiente, tem incentivado pesquisas com a finalidade de encontrar substitutos ambientalmente amigáveis para os eficientes sistemas à base de cromo hexavalente (Cr6+), que são empregados como pré-tratamento em ligas de alumínio de alta resistência utilizadas na indústria aeronáutica. Neste trabalho, o desempenho do silano BTSE (Bis-1,2-(trietoxisilil) etano) como método de proteção contra a corrosão da liga de alumínio 2024-T3 foi investigado utilizando técnicas de caracterização eletroquímicas, microestruturais e químicas. Para melhorar as propriedades anticorrosivas do sistema, a camada de silano foi modificada pela introdução de aditivos, tendo sido estudados também sistemas em bi-camada. Efeitos das condições de cura (tempo e temperatura) do BTSE e da quantidade de modificantes sobre as propriedades dos substratos revestidos também foram avaliados. Para os estudos eletroquímicos, realizados em solução de NaCl 0,1 M, foram empregadas a espectroscopia de impedância eletroquímica (EIS) e curvas de polarização potenciodinâmica anódica e catódica. As técnicas de caracterização morfológica e microestrutural foram microscopia de força atômica (AFM)...

Desenvolvimento de estruturas do tipo bi-camada baseadas em camadas auto-organizadas e polianilina para a proteção contra a corrosão de ligas de alumínio; Development of structures such as bi-layer based on self-assembled monolayers and polyaniline for corrosion protection of aluminum alloys

Silva, Daiane Piva Barbosa da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 15/04/2010 PT
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Um método amplamente utilizado na proteção contra a corrosão de ligas de alumínio é a formação de camadas de conversão de cromo. Na busca de métodos "ambientalmente amigáveis" de proteção contra corrosão existe a possibilidade da utilização de polímeros condutores, como a polianilina (PAni), que pode atuar por efeito barreira, assim como pela absorção de cargas provenientes da solução e / ou camadas auto-organizadas (SAM, do inglês "self assembled monolayers"), onde a proteção pode ocorrer de forma indireta, quando a SAM atua como promotora de adesão para outros revestimentos ou de forma direta, quando a própria monocamada bloqueia o acesso de substâncias responsáveis pela corrosão, à superfície protegida. Neste trabalho é proposta a utilização de bi-camadas baseadas de propil-trimetóxi-silano (PTMS) + PAni e octadecil-trimetóxi-silano (ODTMS) + PAni para a proteção contra a corrosão das ligas de alumínio AA1050, AA2024 e AA7075. Para os ensaios de corrosão foram utilizadas as técnicas de potencial de circuito aberto, curvas de polarização potenciodinâmica e espectroscopia de impedância eletroquímica. Análise de microscopia óptica e microscopia eletrônica de varredura (MEV) foram realizadas antes e após os ensaios de corrosão para verificar a eficiência de proteção contra corrosão dos revestimentos propostos. Adicionalmente foram realizados testes de névoa salina e aderência...

Proteção contra a corrosão das ligas de alumínio AA7075-T6 e AA8006-F utilizando bicamadas do tipo polianilina e camadas de cerato; Corrosion protection of AA7075-T6 and AA8006-F aluminum alloys using bi-layers based on polyaniline and cerium conversion layers

Bisanha, Leandro Duarte
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 23/01/2014 PT
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O desenvolvimento de novos revestimentos ou métodos de proteção considerados ambientalmente amigáveis é extremamente importante para a substituição das eficientes camadas de conversão do cromo, as quais são amplamente utilizadas para proteção anticorrosiva do alumínio e suas ligas. Entre as alternativas relatadas na literatura, podemos destacar a aplicação de filmes de polianilina (PAni) e o uso de camadas de conversão de cério. Neste trabalho é proposta a utilização de revestimentos do tipo bicamadas formada pela combinação de: 1) duas camadas de polianilina ou 2) camadas de conversão de cério (depositadas pelo método electroless ou catodicamente) e filmes de PAni para proteção contra a corrosão das ligas de alumínio AA7075-T6 e AA8006-F em meio aquoso contendo íons cloreto. Nos ensaios de corrosão foram utilizados o monitoramento do potencial de circuito aberto e a polarização potenciodinâmica em meio de NaCl 0,6 mol L-1. A superfície das ligas com e sem os recobrimentos foram analisadas por microscopia óptica e microscopia eletrônica de varredura. Também foi realizado o teste de aderência dos filmes de PAni presentes nas bicamadas sobre as ligas estudadas. O revestimento bicamada composto por uma camada de filme de PAni quimicamente depositada e um filme casting de PAni apresenta excelente aderência sobre as ligas AA7075-T6 e AA8006-F e combina a proteção oferecida pelos filmes casting com a boa aderência dos filmes de PAni depositados quimicamente. O uso da bicamada de cerato electroless e PAni apresenta propriedades anticorrosivas inferiores quando comparadas ao filme de PAni aplicado diretamente sobre o substrato metálico...

Mapping of an ankyrin-sensitive, phosphatidylethanolamine/phosphatidylcholine mono- and bi-layer binding site in erythroid β-spectrin

Hryniewicz-Jankowska, Anita; Bok, Ewa; Dubielecka, Patrycja; Chorzalska, Anna; Diakowski, Witold; Jezierski, Adam; Lisowski, Marek; Sikorski, Aleksander F.
Fonte: Portland Press Ltd. Publicador: Portland Press Ltd.
Tipo: Artigo de Revista Científica
EN
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It has been shown previously that binding of vesicles and monolayers containing PE (phosphatidylethanolamine) by either erythroid or non-erythroid spectrin proved sensitive to inhibition by purified erythrocyte ankyrin. We tested the lipid-binding affinities of the purified ankyrin-binding domain of β-spectrin and of its truncated mutants in four ways, by analysing: (1) penetration of ‘loose’ PE/PC (phosphatidylcholine) monolayers; (2) binding to liposomes in suspension; (3) competition with spectrin for liposomes; and (4) binding of a PE/PC monolayer in a surface plasmon resonance system. The results obtained indicated that the full-length ankyrin-binding domain bound PE/PC mono- and bi-layers with moderate affinity, penetrated monolayers and competed with spectrin for liposomes. Moreover, its truncated mutants that retained the N-terminal part, in contrast with those lacking eight or 38 N-terminal residues (which bound lipid mono- and bi-layers with lower affinity), bound PE/PC mono- and bi-layers with an affinity and capacity comparable with those of the full-length ankyrin-binding domain, and this activity was inhibited by purified erythrocyte ankyrin. The full-length domain, in contrast with the mutant lacking 38 N-terminal residues...

Minerals of the system Bi-Te-Se-S related to the tetradymite archetype: Review of classification and compositional variation

Cook, N.; Ciobanu, C.; Wagner, T.; Stanley, C.
Fonte: Mineralogical Assoc Canada Publicador: Mineralogical Assoc Canada
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
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Our compilation of ~900 published results of analyses for minerals of the tetradymite series (tellurobismuthite, tetradymite, guanajuatite, paraguanajuatite, kawazulite, skippenite, tsumoite, hedleyite, pilsenite, laitakarite, ikunolite, joséite-A, joséite-B) allows compositional fields among naturally occurring Bi–Te–Se–S compounds to be established. New compositional data for ingodite, laitakarite, pilsenite, kawazulite and tellurobismuthite extend previously known compositional limits. Recognized minerals can, for the most part, be satisfactorily and conveniently classified according to the ratio Bi(+ Pb)/(Te + Se + S), into the subsystems (isoseries) Bi2Te3–Bi2Se3–Bi2S3, Bi4Te3–Bi4Se3–Bi4S3 and BiTe–BiSe–BiS. Most minerals show limited compositional variation, but this is generally more extensive in the Se-bearing phases (e.g., laitakarite) and in certain members of the system Bi–Te, such as hedleyite and tsumoite. Substitution of minor Pb for Bi is widespread throughout the group, especially in the Bi4Te3–Bi4Se3–Bi4S3 subgroup. Several possible additional minerals or compositional variants of existing minerals would appear to exist in nature, including Bi4Te2Se, Bi4Te(Se,S)2, Bi3Te2Se and Bi3(Te,S,Se)4. Within the above groups...

Superconductor-Ferromagnet Bi-Layers: a Comparison of s-Wave and d-Wave Order Parameters

Lueck, T.; Eckern, U.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 28/02/2004
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We study superconductor-ferromagnet bi-layers, not only for s-wave but also for d-wave superconductors. We observe oscillations of the critical temperature when varying the thickness of the ferromagnetic layer for both s-wave and d-wave superconductors. However, for a rotated d-wave order parameter the critical temperature differs considerably from that for the unrotated case. In addition we calculate the density of states for different thicknesses of the ferromagnetic layer; the results reflect the oscillatory behaviour of the superconducting correlations.; Comment: 11 pages, 5 figures, accepted for publication in J. Phys.: Condens. Matter

Tunneling of Obliquely-Incident Waves through PT-Symmetric Epsilon-Near-Zero Bi-Layers

Savoia, Silvio; Castaldi, Giuseppe; Galdi, Vincenzo; Alu', Andrea; Engheta, Nader
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
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We show that obliquely-incident, transversely-magnetic-polarized plane waves can be totally transmitted (with zero reflection) through epsilon-near-zero (ENZ) bi-layers characterized by balanced loss and gain with parity-time (PT) symmetry. This tunneling phenomenon is mediated by the excitation of a surface-wave localized at the interface separating the loss and gain regions. We determine the parameter configurations for which the phenomenon may occur and, in particular, the relationship between the incidence direction and the electrical thickness. We show that, below a critical threshold of gain and loss, there always exists a tunneling angle which, for moderately thick (wavelength-sized) structures, approaches a critical value dictated by the surface-wave phase-matching condition. We also investigate the unidirectional character of the tunneling phenomenon, as well as the possible onset of spontaneous symmetry breaking, typical of PT-symmetric systems. Our results constitute an interesting example of a PT-symmetry-induced tunneling phenomenon, and may open up intriguing venues in the applications of ENZ materials featuring loss and gain.; Comment: 11 pages, 12 figures (minor revisions in the text and figures)

Activation gap in the specific heat measurements for He$^3$ bi-layers

Rançon-Schweiger, Adam; Benlagra, Adel; Pépin, Catherine
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
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Recently, attention has been given to a system of He$^3$ bi-layers where a quantum criticality similar to the one in heavy fermion compounds has been observed [Science 317, 1356 92007)] In our previous analysis [Phys. Rev. B 79, 045112 (2007)], based on the Kondo breakdown scenario, we addressed successfully most of the features observed in that experiment. Here, we consider the activation energy $\Delta$ observed experimentally in the specific heat measurements at low temperatures in the heavy Fermi liquid phase. Within our previous study of this system, this is identified with the gap opening when the upper hybridized band is emptied due to a strong hybridization between the nearly localized first layer and the fluid second one. We discuss the successes and limitations of our approach. An additional prediction is proposed.; Comment: 6 pages, 6 figures - replaced with the published version

Transformation-optics generalization of tunnelling effects in bi-layers made of paired pseudo-epsilon-negative/mu-negative media

Castaldi, Giuseppe; Gallina, Ilaria; Galdi, Vincenzo; Alu', Andrea; Engheta, Nader
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
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Transformation-media designed by standard transformation-optics (TO) approaches, based on real-valued coordinate-mapping, cannot exhibit single-negative (SNG) character unless such character is already possessed by the domain that is being transformed. In this paper, we show that, for a given field polarisation, pseudo-SNG transformation media can be obtained by transforming a domain featuring double positive (or double-negative) character, via complex analytic continuation of the coordinate transformation rules. Moreover, we apply this concept to the TO-based interpretation of phenomena analogous to the tunnelling effects observable in bi-layers made of complementary epsilon-negative (ENG) and mu-negative (MNG) media, and explore their possible TO-inspired extensions and generalizations.; Comment: 13 pages, 1 table, 6 figures; minor changes in the title and text

Topological insulator in a Bi-Bi$_2$Se$_3$ infinitely adaptive superlattice phase

Valla, T.; Ji, Huiwen; Schoop, L. M.; Weber, A. P.; Pan, Z. -H.; Sadowski, J. T.; Vescovo, E.; Fedorov, A. V.; Caruso, A. N.; Gibson, Q. D.; Muchler, L.; Felser, C.; Cava, R. J.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
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We report spin- and angle-resolved photoemission studies of a topological insulator from the infinitely adaptive series between elemental Bi and Bi$_2$Se$_3$. The compound, based on Bi$_4$Se$_3$, is a 1:1 natural superlattice of alternating Bi$_2$ layers and Bi$_2$Se$_3$ layers; the inclusion of S allows the growth of large crystals, with the formula Bi$_4$Se$_{2.6}$S$_{0.4}$. The crystals cleave along the interfaces between the Bi$_2$ and Bi$_2$Se$_3$ layers, with the surfaces obtained having alternating Bi or Se termination. The resulting terraces, observed by photoemission electron microscopy, create avenues suitable for the study of one-dimensional topological physics. The electronic structure, determined by spin- and angle- resolved photoemission spectroscopy, shows the existence of a surface state that forms a large, hexagonally shaped Fermi surface around the $\Gamma$ point of the surface Brillouin zone, with the spin structure indicating that this material is a topological insulator.; Comment: published version, 5 pages, 4 figures

Silicene Beyond Mono-layers - Different Stacking Configurations And Their Properties

Kamal, C.; Chakrabarti, Aparna; Banerjee, Arup; Deb, S. K.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 17/10/2012
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We carry out a computational study on the geometric and electronic properties of multi-layers of silicene in different stacking configurations using a state-of-art abinitio density functional theory based calculations. In this work we investigate the evolution of these properties with increasing number of layers (n) ranging from 1 to 10. Though, mono-layer of silicene possesses properties similar to those of graphene, our results show that the geometric and electronic properties of multi-layers of silicene are strikingly different from those of multi-layers of graphene. We observe that there exist strong inter-layer covalent bondings between the layers in multi-layers of silicene as opposed to weak van der Waal's bonding which exists between the graphene layers. The inter-layer bonding strongly influences the geometric and electronic structures of these multi-layers. Like bi-layers of graphene, silicene with two different stacking configurations AA and AB exhibits linear and parabolic dispersions around the Fermi level, respectively. However, unlike graphene, for bi-layers of silicene, these dispersion curves are shifted in band diagram; this is due to the strong inter-layer bonding present in the latter. For n > 3, we study the geometric and electronic properties of multi-layers with four different stacking configurations namely...

Coupling of magnetic order to planar Bi electrons in the anisotropic Dirac metals AMnBi2 (A = Sr, Ca)

Guo, Y. F.; Princep, A. J.; Zhang, X.; Manuel, P.; Khalyavin, D.; Mazin, I. I.; Shi, Y. G.; Boothroyd, A. T.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
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We report powder and single crystal neutron diffraction measurements of the magnetic order in AMnBi2 (A = Sr and Ca), two layered manganese pnictides with anisotropic Dirac fermions on a Bi square net. Both materials are found to order at TN approx 300 K in k = 0 antiferromagnetic structures, with ordered Mn moments at T = 10 K of approximately 3.8 muB aligned along the c axis. The magnetic structures are Neel-type within the Mn--Bi layers but the inter-layer ordering is different, being antiferromagnetic in SrMnBi2 and ferromagnetic in CaMnBi2. This allows a mean-field coupling of the magnetic order to Bi electrons in CaMnBi2 but not in SrMnBi2. We find clear evidence that magnetic order influences electrical transport. First principles calculations explain the experimental observations and suggest that the mechanism for different inter-layer ordering in the two compounds is the competition between the anteiferromagnetic superexchange and ferromagnetic double exchange carried by itinerant Bi electrons.; Comment: Accepted for publication in Physical Review B. Version 2 includes additional sample characterisation and bulk measurements, and ab initio electronic structure calculations

Surface roughness analysis of the hydrophilic SiO_2/TiO_2 nano bi-layers by Level crossing approach

Daryaei, E.; Tabar, M. Reza Rahimi; Moshfegh, A. Z.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 20/08/2013
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The effect of etching time on the statistical properties of the hydrophilic surface of SiO_2/TiO_2/Glass nano bi-layer has been studied using Atomic Force Microscopy (AFM) and stochastic approach based on the level crossing analysis. We have created a rough surface of the hydrophilic SiO_2/TiO_2 nano bi-layer system by using 26% Potassium Hydroxide (KOH) solution. Measuring the average apparent contact angle assessed the degree of hydrophilicity and the optimum condition was determined at 10 min etching time. Level crossing analysis based on AF images provided deeper insight into the microscopic details of the surface topography. For different etching time, it has been shown that the average frequency of visiting a height with positive slope behaves Gaussian for heights near the mean value and obeys power law for the heights far away from the mean value. Finally, by applying the generalized total number of crossings with positive slope, it was found that the both high heights and deep valleys of the surface are extremely effective in hydrophilic degree of the SiO_2/TiO_2/Glass nano bi-layer investigated system.

Calculation of magnetic exchange couplings in S=3/2 honeycomb system Bi$_3$Mn$_4$O$_{12}$(NO$_3$)} from first principles

Kandpal, Hem C.; Brink, Jeroen van den
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
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Absence of magnetic ordering in Bi$_3$Mn$_4$O$_{12}$(NO$_3$), (BMNO) which has a magnetic subsystem that consists of honeycomb bi-layers of Mn$^{4+}$ ions with spin S=3/2, has raised the expectation that its ground state is strongly frustrated due to longer-range antiferromagnetic interactions. We calculate the magnetic exchange coupling constants of the BMNO complex within a density functional approach and find that the dominating interactions between Mn spins are the antiferromagnetic nearest-neighbor $J_1$ and interlayer interaction $J_c$. The largest interaction is $J_c$, which substantially exceeds $J_1$. Longer-range interactions are antiferromagnetic, but only weakly frustrating.; Comment: 4 pages, 2 figures - accepted for publication in Physical Review B (Rapid Comm.)

He3 bi-layers as a simple example of de-confinement

Benlagra, Adel; Pépin, Catherine
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
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We consider the recent experiments on He3 bi-layers, showing evidence for a quantum critical point (QCP) at which the first layer localizes. Using the Anderson lattice in two dimensions with the addition of a small dispersion of the f-fermion, we modelize the system of adsorbed He3 layers. The first layer represents the f-fermions at the brink of localization while the second layer behaves as a free Fermi sea. We study the quantum critical regime of this system, evaluate the effective mass in the Fermi liquid phase and the coherence temperature and give a fit of the experiments and interpret its main features. Our model can serve as well as a predictive tool used for better determination of the experimental parameters.; Comment: 15 pages, 15 figures. Submitted to PRB

Magnetic and magneto-transport characterization of (Ga,Mn)(Bi,As) epitaxial layers

Levchenko, K.; Andrearczyk, T.; Domagala, J. Z.; Wosinski, T.; Figielski, T.; Sadowski, J.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 19/06/2014
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High-quality layers of the (Ga,Mn)(Bi,As) quaternary compound semiconductor have been grown by the low-temperature molecular-beam epitaxy technique. An effect of Bi incorporation into the (Ga,Mn)As ferromagnetic semiconductor and the post-growth annealing treatment of the layers have been investigated through examination of their magnetic and magneto-transport properties. Significant enhancement of the planar Hall effect magnitude upon addition of Bi into the layers is interpreted as a result of increased spin-orbit coupling in the (Ga,Mn)(Bi,As) layers.; Comment: 9 pages, 3 figures, to be published in the proceedings of the "43rd "Jaszowiec" International School and Conference on the Physics of Semiconductors", June 7-12, 2014, Wisla, Poland

X-ray photoemission study of CoFeB/MgO thin film bi-layers

Read, J. C.; Mather, P. G.; Buhrman, R. A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 09/02/2007
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We present results from an X-ray photoemission spectroscopy (XPS) study of CoFeB/MgO bi-layers where we observe process-dependent formation of B, Fe, and Co oxides at the CoFeB/MgO interface due to oxidation of CoFeB during MgO deposition. Vacuum annealing reduces the Co and Fe oxides but further incorporates B into the MgO forming a composite MgBxOy layer. Inserting an Mg layer between CoFeB and MgO introduces an oxygen sink, providing increased control over B content in the barrier.; Comment: 13 pages, 3 figures

A Self-timed implementation of the bi-way sorter systolic array processor

Diamond, Mitchell
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
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Self-timed circuits with an appropriate handshake control circuit can be used to replace the global clock in a VLSI chip. By replacing the global clock many problems which face designers have disappeared along with the clock. Some of these problems are due to clock skew and capacitance scaling with smaller feature sizes. The wire capacitance cannot scale below a certain limit due to two-dimensional effects, therefore the RC delays associated with the interconnect layers do not scale proportion.ally to the feature size. The resultant increase in wire delay makes it difficult to distribute a global clock at a high frequency. This project takes an existing synchronous systolic array, the bi-way sorter, and implements the sorter algorithm using a self-timed approach. By using self-timed instead of synchronous approaches, many of the problems associated with synchronous circuits such as clock skew and large line capacitance, are avoided. In this thesis, a 2-bit, four number sorter will be designed and simulated and the advantages and drawbacks will be examined.

Study of the Anticorrosive Properties of Different Bi-Layers of Polypyrrole - BTSE on Carbon Steel Immersed in NaCl Media

Correa-Borroel,A.L.; Gutierrez,S.; Estrada,E. Arce; Cabrera-Sierra,R.; Herrasti,P.
Fonte: Sociedade Portuguesa de Electroquímica Publicador: Sociedade Portuguesa de Electroquímica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2010 EN
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To improve the corrosion resistance of mild steel, in this work, bi-layers of BTSE (bis-(triethoxysilyl) ethane) and Ppy coatings have been deposited via adsorption and electrodeposition, respectively. The anticorrosive properties of these bi-layers have been evaluated in an aggressive medium like 3% NaCl, and compared with the layers of BTSE and Ppy in a separate way. In spite of the aggressive solution, it was evaluated a poor behaviour of both Ppy and BTSE coatings using potential measurements, EIS and SEM techniques. A better behaviour was expected because the preparation of the bi-layers Ppy/BTSE and BTSE/Ppy showed a protective behaviour using SEM and salt spray tests. However, EIS results predicted an evolution of these coatings for long immersion times being evident the oxidation of the steel.