Implement and soil condition effects on tillage-induced erosion

Water, wind, or tillage-induced soil erosion can significantly degrade soil quality. Therefore, understanding soil displacement through tillage translocation is an important step toward developing tillage practices that do not degrade soil resources. Our primary objective was to determine the effects of soil condition (i.e. grassland stubble versus previously tilled soil), opening angle, and harrow speed on soil translocation. A second field study also conducted on a Lixisol but only in the stubble field, quantified displacement effects of mouldboard ploughing. The field studies were located 12 km South of Évora, Portugal. Soil displacement or translocation after each tillage operation in both studies was measured using aluminium cubes with a side length of 15mm as ‘tracers’. Offset angles for the harrow disk were 20◦, 44◦ and 59◦; tractor velocities ranged from 1.9 to 7.0 km h−1 and tillage depth ranged from 4 to 11 cm. The depth of mouldboard ploughing was approximately 40 cm with a wheel speed of 3.7 km h−1. The translocation coefficients for the two implements were very different averaging 770 kgm−1 for the mouldboard plough and ranging from 9 to 333 kgm−1 for the harrow disk. This shows that the mouldboard plough was more erosive than the harrow disk in these studies. All three variables (soil condition, opening angle, and tillage velocity) were critical factors affecting the translocation coefficient for the harrow disk. Displacement distances were the largest for compacted soils (stubble field), with higher opening or offset angles, and at higher velocities. The results also showed significant correlation for (a) mean soil displacement in the direction of tillage and the slope gradient and (b) soil transport coefficient and the opening angle. Our results can be used to predict the transport coefficient (a potential soil quality indicator for tillage erosion) for the harrow disk, provided tillage depth, opening angle, and tool operating speed are known

Effect of material hybridization on the strength of scarf adhesive joints

Adhesively-bonded joints have become more efficient due to the improvement of adhesives’ characteristics. On the other hand, with the use of composites in structures it is possible to reduce weight. Due to this, new techniques are being explored, including adhesively-bonding different materials. Nowadays, in many high performance structures, it is necessary to combine composite materials with other light-weighted metals such as aluminium or titanium. This work reports on an experimental and numerical study for hybrid scarf joints between composite and aluminium adherends, and considering different values of the scarf angle (α). The numerical analysis by Finite Elements (FE), using the software Abaqus®, enabled the obtainment of peel (σy) and shear stresses (τxy), which are then used to discuss the strength between different joint configurations. Cohesive zone modelling (CZM) was used to predict the joint strength and the results were compared to the experiments for validation. The joints’ behaviour was highly dependent on α, and CZM were validated for the design process of hybrid scarf joints.info:eu-repo/semantics/publishedVersio

Uma nota didáctica breve no uso esclarecido de procedimentos estatísticos em análise de dados repetidos no tempo. Um estudo guiado para investigadores em Ciências do Desporto

Este texto pretende ser um auxiliar didáctico no uso esclarecido de procedimentos estatísticos relativos à análise longitudinal de dados. Servir-nos-emos de um exemplo ilustrativo de complexidade crescente para introduzir a estrutura de um delineamento de grupo único e da essência do ensaio de hipóteses estatísticas. De seguida apresentamos os principais resultados do uso de teste t e da análise de variância de medidas repetidas. Os resultados são interpretados de modo formal e substantivo, introduzindo um pensamento alternativo à estrutura binária do resultado do ensaio de hipóteses. O recurso a procedimentos gráficos é fortemente explorado. Finalmente, recorremos à modelação hierárquica para salientar a sua riqueza e flexibilidade interpretativa no estudo de dados longitudinais

Encapsulation efficiency of Lactobacillus plantarum microencapsulado in Acrycoat S100

Several studies have attributed health benefits to probiotics, as the contribution to intestinal microflora activity (Khan et al. 2013). However, adverse conditions in gastrointestinal transit can reduce the viability of probiotics as Lactobacillus plantarum. Acrycoat S100 is a co-polymer from methacrylic acid and methyl methacrylate, water insoluble and soluble in pH ≥ 7. Therefore, microencapsulation of probiotic in Acrycoat S100 could allow microorganism protection until it reach the intestine. The objective of this study was to determine the encapsulation efficiency of L. plantarum microencapsulated in Acrycoat S100.info:eu-repo/semantics/publishedVersio

Dados longitudinais e modelação hierárquica. Um tutorial para investigadores das Ciências do Desporto

Este texto pretende ser um auxiliar didáctico sobre modos de olhar informação de natureza longitudinal. O seu propósito fundamental é auxiliar os investigadores a recorrerem à Modelação Hierárquica ou Multinível (MHMN) para extraírem dos dados toda a sua riqueza. Na primeira parte apresentaremos as ideias fundamentais da MHMN aplicadas a dados longitudinais. De seguida recorreremos a um exemplo complexo para apresentar todos os passos da MHMN, interpretando de modo substantivo as principais estatísticas produzidas pelo software HLM 6.0

Análise e interpretação dos níveis de actividade física de crianças: um tutorial baseado na modelação hierárquica ou multinível

Este tutorial pretende apresentar, de modo didáctico, uma forma alternativa de análise de dados sobre os níveis de actividade física de crianças a partir da modelação hierárquica ou multinível. São mencionadas as diferentes etapas da modelação, os resultados são interpretados com base nos output's do software utilizado – o HLM 6.02. Em cada etapa do percurso são lançadas as hipóteses mais importantes em grau de complexidade crescente. A sua importância é referida a partir dos resultados disponíveis

Sub-terahertz, microwaves and high energy emissions during the December 6, 2006 flare, at 18:40 UT

The presence of a solar burst spectral component with flux density increasing with frequency in the sub-terahertz range, spectrally separated from the well-known microwave spectral component, bring new possibilities to explore the flaring physical processes, both observational and theoretical. The solar event of 6 December 2006, starting at about 18:30 UT, exhibited a particularly well-defined double spectral structure, with the sub-THz spectral component detected at 212 and 405 GHz by SST and microwaves (1-18 GHz) observed by the Owens Valley Solar Array (OVSA). Emissions obtained by instruments in satellites are discussed with emphasis to ultra-violet (UV) obtained by the Transition Region And Coronal Explorer (TRACE), soft X-rays from the Geostationary Operational Environmental Satellites (GOES) and X- and gamma-rays from the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The sub-THz impulsive component had its closer temporal counterpart only in the higher energy X- and gamma-rays ranges. The spatial positions of the centers of emission at 212 GHz for the first flux enhancement were clearly displaced by more than one arc-minute from positions at the following phases. The observed sub-THz fluxes and burst source plasma parameters were found difficult to be reconciled to a purely thermal emission component. We discuss possible mechanisms to explain the double spectral components at microwaves and in the THz ranges.Comment: Accepted version for publication in Solar Physic

Characterizing top gated bilayer graphene interaction with its environment by Raman spectroscopy

In this work we study the behavior of the optical phonon modes in bilayer graphene devices by applying top gate voltage, using Raman scattering. We observe the splitting of the Raman G band as we tune the Fermi level of the sample, which is explained in terms of mixing of the Raman (Eg) and infrared (Eu) phonon modes, due to different doping in the two layers. We theoretically analyze our data in terms of the bilayer graphene phonon self-energy which includes non-homogeneous charge carrier doping between the graphene layers. We show that the comparison between the experiment and theoretical model not only gives information about the total charge concentration in the bilayer graphene device, but also allows to separately quantify the amount of unintentional charge coming from the top and the bottom of the system, and therefore to characterize the interaction of bilayer graphene with its surrounding environment

Exploiting the Power of mip Solvers in maxsat

Abstract. maxsat is an optimization version of satisfiability. Since many practical problems involve optimization, there are a wide range of potential applications for effective maxsat solvers. In this paper we present an extensive empirical evaluation of a number of maxsat solvers. In addition to traditional maxsat solvers, we also evaluate the use of a state-of-the-art Mixed Integer Program (mip) solver, cplex, for solving maxsat. mip solvers are the most popular technology for solving opti-mization problems and are also theoretically more powerful than sat solvers. In fact, we show that cplex is quite effective on a range of maxsat instances. Based on these observations we extend a previously developed hybrid approach for solving maxsat, that utilizes both a sat solver and a mip solver. Our extensions aim to take better advantage of the power of the mip solver. The resulting improved hybrid solver is shown to be quite effective.