3,575 research outputs found
Capacitive Coupling of Two Transmission Line Resonators Mediated by the Phonon Number of a Nanoelectromechanical Oscillator
Detection of quantum features in mechanical systems at the nanoscale
constitutes a challenging task, given the weak interaction with other elements
and the available technics. Here we describe how the interaction between two
monomodal transmission-line resonators (TLRs) mediated by vibrations of a
nano-electromechanical oscillator can be described. This scheme is then
employed for quantum non-demolition detection of the number of phonons in the
nano-electromechanical oscillator through a direct current measurement in the
output of one of the TLRs. For that to be possible an undepleted field inside
one of the TLR works as a amplifier for the interaction between the mechanical
resonator and the remaining TLR. We also show how how the non-classical nature
of this system can be used for generation of tripartite entanglement and
conditioned mechanical coherent superposition states, which may be further
explored for detection processes.Comment: 6 pages, 5 figure
Two-dimensional open microfluidic devices by tuning the wettability on patterned superhydrophobic polymeric surface
We present a simple and economical method to produce a potential open microfluidic polymeric device. Biomimetic superhydrophobic surfaces were prepared on polystyrene using a phase separation methodology. Patterned two-dimensional channels were imprinted on the superhydrophobic substrates by exposing the surface to plasma or UV–ozone radiation. The wettability of the channels could be precisely controlled between the superhydrophobic and superhydrophilic states by changing the exposure time. The ability of superhydrophilic paths to drive liquid flows in a horizontal position was found to be significantly higher than for the case of hydrophilic paths patterned onto smooth surfaces.(undefined
Frações de C Orgânico Oxidável em Função do Uso de Plantas de Cobertura em Pomar de Laranjeira Pera no Litoral Norte da Bahia.
O uso de coberturas vegetais afeta o conteúdo total da matéria orgânica do solo, porém, poucos estudos demonstram qual o efeito desse manejo sobre a qualidade do C orgânico do solo. O objetivo deste estudo foi determinar a variação de frações de C orgânico do solo com diferentes graus de labilidade a partir do uso de diferentes plantas de cobertura, em cultivos solteiro ou consorciado, em um pomar de laranjeira ?Pera?. O experimento foi instalado na Fazenda Lagoa do Coco, município de Rio Real, Bahia em um pomar de laranja ?Pera? enxertada em limoeiro ?Cravo?. Foram utilizadas as seguintes espécies de cobertura: Braquiária (BRAQ), Feijão-de-porco (FP), Milheto (MILH) e a combinação 50% feijão-de-porco+milheto (FP+MILH). Amostras de solo foram coletadas nas entrelinhas do pomar nas profundidades de 0-10 e 10-20 cm. Foram determinados os teores totais de C orgânico (COT) e frações de C com diferentes graus de labilidade obtidas por meio do uso de doses crescentes de H2SO4. Independente do tratamento, os maiores teores de C ocorreram na fração de maior labilidade (F1), o que representou em média 48% do COT. A fração F4 representou cerca de 12% do COT. Os tratamentos FP+MILH e VE foram os que favoreceram maiores proporções de C na F4, representando, respectivamente, 19 e 12% do COT na camada superficial. As espécies MILH e FP proporcionam maior disponibilidade de C orgânico nas frações mais lábeis. A fração F1 pode ser considerada um indicador mais sensível às mudanças na matéria orgânica proporcionadas pelo manejo
Optimal Categorical Attribute Transformation for Granularity Change in Relational Databases for Binary Decision Problems in Educational Data Mining
This paper presents an approach for transforming data granularity in
hierarchical databases for binary decision problems by applying regression to
categorical attributes at the lower grain levels. Attributes from a lower
hierarchy entity in the relational database have their information content
optimized through regression on the categories histogram trained on a small
exclusive labelled sample, instead of the usual mode category of the
distribution. The paper validates the approach on a binary decision task for
assessing the quality of secondary schools focusing on how logistic regression
transforms the students and teachers attributes into school attributes.
Experiments were carried out on Brazilian schools public datasets via 10-fold
cross-validation comparison of the ranking score produced also by logistic
regression. The proposed approach achieved higher performance than the usual
distribution mode transformation and equal to the expert weighing approach
measured by the maximum Kolmogorov-Smirnov distance and the area under the ROC
curve at 0.01 significance level.Comment: 5 pages, 2 figures, 2 table
Aporte de carbono e macronutrientes de coberturas vegetais em pomar de laranjeira Pera no litoral norte do Estado da Bahia.
A inclusão de culturas de coberturas no sistema de produção de citros pode ser uma alternativa viável para o aumento do sequestro de C e melhorias para a ciclagem de nutrientes. O objetivo deste trabalho foi avaliar a produção de matéria seca, o teor e o acúmulo de carbono e macronutrientes de palhadas de diferentes plantas de cobertura em cultivos solteiro ou consorciado em pomar de laranjeira ?Pera? nas condições da região do Litoral Norte do Estado da Bahia. Foram utilizadas as seguintes espécies de cobertura: Braquiária (Brachiaria decumbens), Feijão-de-porco (Canavalia ensiformis), e Milheto (Pennisetum americanum). Foram avaliados: a produção de matéria seca, estoques de C e nutrientes na matéria seca e os teores totais de C orgânico do solo. A leguminosa FP apresentou baixo potencial para sequestrar C, por outro lado, pode ser considerada uma excelente (re)cicladora de N, K, Ca e S. O tratamento MILH revelou grande potencial para (re)ciclar C, P, K e Mg, similar à gramínea BRAQ. De modo geral, o cultivo combinado FP+MILH apresentou maior potencial de ciclagem de nutrientes em relação aos cultivos solteiros, representando uma excelente opção de manejo para o uso de cobertura em pomar cítrico. A vegetação espontânea apresenta um papel ecológico importante para a ciclagem de C e nutrientes. Sua eliminação total do pomar cítrico representa uma perda substancial de C e nutrientes do sistema. Os teores de C orgânico total do solo são pouco afetados pelo cultivo de coberturas vegetais a curto
Combinatorial analysis of marine based biomaterials: high-throughput analysis of the effect of nanostructured multilayers on cell behaviour
Publicado em "Journal of Tissue Engineering and Regenerative Medicine", vol. 7, supp. 1 (2013)In a marine environment, specific proteins are secreted by mussels and used as a bioglue to stick to a surface allowing generate irreversible bonding. Adhesive secreted proteins of mussels present an unusual amino acid 3,4-dihydroxyphenylalanine (DOPA). Inspired by the struc- ture and properties of mussel adhesive proteins, layer-by-layer (LbL) coatings based on polymers that contain catechol groups were devel- oped. We used dopamine-modified hyaluronic acid (HA-DN) prepared by carbodiimide chemistry to form thin and surface-adherent dopamine films. The multilayer films were developed by electrostatic interactions using chitosan (CHT) as polycation and HA-DN as polyanion. Multilay- ers films of CHT and HA were used as control. The formation of these films was investigated in-situ by quartz crystal microbalance with dissi- pation monitoring (QCM-D). Afterwards, many combinations of the marine inspired biomaterials were analysed in a high-throughput (HTS) way. Such multilayers were constructed and individually dis- posed on isolated transparent spots, patterned onto biomimetic super- hydrophobic substrates. The adhesion properties of the coatings in the chips were also analyzed. In vitro tests using two distinct cell sources were carried out to evaluate the biological performance of the different combinations of multilayers that could be useful in different biomedical applications, including tissue engineering
Considering the stiffness of the forming tools in the numerical analysis of the ironing process
Ironing can occur in cylindrical cup drawing whenever the thickness of the drawn flange is larger than the gap between the punch and the die. This is particularly relevant for materials that present r-values lower than 1.0, such as the aluminium alloys, since they tend to present more thickening of the flange. The aim of this study is to evaluate numerically the impact of the elastic deformation of the forming tools on the final cup geometry, i.e., the earing profile and the evolution of thickness along the circumferential direction, at different heights. Different contact conditions are also analysed since they strongly affect both the thickness strain and the earing profile. The process conditions considered are the ones from EXACT, the ESAFORM Benchmark 2021, enabling the comparison with experimental results. Considering the deformation of the forming tools mainly impacts the ironing stage, enabling predicting wall thickness values larger than the gap between the punch and the die.The authors gratefully acknowledge the financial support of the Portuguese Foundation for Science and Technology (FCT) under projects with reference 2022.08459.PTDC, UIDB/00285/2020 and LA/P/0112/2020
Influence of the orthotropic behaviour on defects prediction in cup drawing, reverse redrawing and expansion
Finite elements analysis is commonly used in the cans tool design since it allows predicting different sheet metal defects and instabilities that significantly affect the efficient production of beverage cans. These defects include caring, due to the material orthotropic behaviour, thinning and fracture. The numerical prediction of these kind of defects is more complex when different combinations of strain paths are involved. The process conditions considered in this work involve the drawing of a cylindrical cup, the reverse redrawing and the expansion. The two materials under analysis are an AA5352 aluminium alloy and a TH330 steel. The materials orthotropic plastic behaviour is modelled with a non-quadratic yield criterion. The results show that changes in the yield surface lead to slight changes in the caring profile and in the location were strain localization occurs. Moreover, the numerical model must describe in detail the process conditions, since they may affect the formability prediction.The authors would like to acknowledge the funding from of the Foundation for Science and Technology (FCT) under projects with reference PTDC/EME-EME/30592/2017 and PTDC/EME-EME/31243/2017 and by European Regional Development Fund (ERDF) through the Portugal 2020 program and the Centro 2020 Regional Operational Programme (CENTRO-01-0145-FEDER-031657) under project MATIS (CENTRO-01-0145-FEDER-000014) and UID/EMS/00285/2020
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