Circulation induced by diffused aeration in a shallow lake

Field surveys were carried out to investigate the surface jet flows and the resulting circulation patterns generated by diffused aeration in a shallow lake. In conrast to previous studies, the experimental conditions included point-source bubble plumes with very high air flow rates (100–400 L/min) relative to the shallow water depth (1.5 m). The results indicate that the surface jet velocity can be described by linear profiles. The decay of this velocity with distance displayed a similar behaviour to that reported in the literature, but the surface jet spread much faster under the present conditions. Combining our results with published data allowed for the generation of dimensionless correlations for the velocity and depth of the surface jet. A good agreement between the total circulation flow rates predicted by using the proposed correlations and integral modelling was also obtained. Lastly, a simple returning flow model was proposed to describe the circulation flow patterns induced by the bubble plumes. The results were also applied to assess the impact of circulation on vertical algae migration, which is important for water quality management.Keywords: aeration, algae migration, bubbles, jets, plume

Globalização: Uma Teoria Nova?

A proposta do presente artigo é refletir a respeito da inserção externa dos países do chamado “Sul Global” e as suas consequências para o seu desenvolvimento econômico, além de questionar se as teorias desenvolvidas sobre “globalização” são teorias novas. Para tanto, apresenta a análise de teóricos que estudaram a “globalização”, como Alice Amsden e Peter Evans, e depois a compara com os autores marxistas que trataram do “Imperialismo”, Lênin e Bukharin. Ao final, conclui-se que não existem diferenças relevantes entre os processos econômicos que compõem aquilo que os marxistas chamaram de “Imperialismo” em relação ao que os teóricos recentes definiram como “globalização”. A divergência é em relação ao corolário político que cada uma das correntes teóricas retira da sua análise

A PERCEPÇÃO CLIMÁTICA DA OCORRÊNCIA DE ESTIAGENS E OS PROBLEMAS DE ABASTECIMENTO DE ÁGUA NA ÁREA URBANA DO MUNICÍPIO DE BAGÉ - RS

As estiagens fazem parte do cotidiano da população sul-rio-grandense, as quais afetam o desenvolvimento regional. Nesta pesquisa, avaliou-se quantitativamente a percepção ambiental dos moradores urbanos de Bagé, RS, sobre a ocorrência de estiagens e seus impactos relacionados ao uso da água. O estudo baseou-se na metodologia utilizada por Wollmann; Sartori (2010) e Ribeiro (2012), que consiste na aplicação de questionário de perguntas abertas e fechadas para a população de áreas atingidas por extremos climáticos. Observou-se que a população percebe a ocorrência de estiagem há pelos menos 25 anos, e tal situação climática leva à ocorrência de falta de água, no verão em Bagé, há pelo menos duas décadas, bem como se observou o descaso com o uso da água.Droughts are part of everyday life of the population south of Rio Grande do Sul which affect regional development. This research concerns in evaluate quantitatively the environmental perception of urban residents Bagé, RS, on the occurrence of drought and its impacts related to water use. The study was based on the methodology used by Wollmann, Sartori (2010) and Ribeiro (2012), which consists of a questionnaire of open and closed questions for the population of areas hit by weather extremes. It was observed that people perceive the occurrence of drought there are at least 25 years, such a climate situation leads to the occurrence of lack of water in summer Bagé, there are at least two decades and was observed using the disregard of water

Sun-induced chlorophyll fluorescence III:Benchmarking retrieval methods and sensor characteristics for proximal sensing

The interest of the scientific community on the remote observation of sun-induced chlorophyll fluorescence (SIF) has increased in the recent years. In this context, hyperspectral ground measurements play a crucial role in the calibration and validation of future satellite missions. For this reason, the European cooperation in science and technology (COST) Action ES1309 OPTIMISE has compiled three papers on instrument characterization, measurement setups and protocols, and retrieval methods (current paper). This study is divided in two sections; first, we evaluated the uncertainties in SIF retrieval methods (e.g., Fraunhofer line depth (FLD) approaches and spectral fitting method (SFM)) for a combination of off-the-shelf commercial spectrometers. Secondly, we evaluated how an erroneous implementation of the retrieval methods increases the uncertainty in the estimated SIF values. Results show that the SFM approach applied to highresolution spectra provided the most reliable SIF retrieval with a relative error (RE) ≤6% and <5% for F687 and F760, respectively. Furthermore, although the SFM was the least affected by an inaccurate definition of the absorption spectral window (RE = 5%) and/or interpolation strategy (RE = 15%– 30%), we observed a sensitivity of the SIF retrieval for the simulated training data underlying the SFM model implementation

Irrigation and nitrogen managements for producing bean plants under no-tillage system

Common bean has been cultivated by producers who have access to a wide range of technologies that allow a higher profitability in the winter. This study aimed at evaluating bean yield and its components, under no-tillage system, according to different irrigation and nitrogen fertilization managements, in Aquidauana, Mato Grosso do Sul State, Brazil. The experiment was carried out from June to September (2010), in the Universidade Estadual de Mato Grosso do Sul, in an Alfisol. The "Pérola" cultivar was sown in June and irrigated by conventional sprinkling. The experimental design was randomized blocks, with split-plots consisting of three blocks and two replications in each block. The plots consisted of three irrigation systems (Class "A" pan and Hargreaves-Samani and Penman-Monteith equations) and the subplots of four nitrogen fertilizing doses (0 kg ha-1, 50 kg ha-1, 100 kg ha-1 and 150 kg ha-1). Data were evaluated with the aid of variance analysis and compared by the Tukey test (5%) and regression models. Bean plants reached the highest grain yield and number of pods per plant when the Class "A" pan irrigation system was used. Nitrogen doses did not affect bean yield

Sun-induced chlorophyll fluorescence I:Instrumental considerations for proximal spectroradiometers

Growing interest in the proximal sensing of sun-induced chlorophyll fluorescence (SIF) has been boosted by space-based retrievals and up-coming missions such as the FLuorescence EXplorer (FLEX). The European COST Action ES1309 &#8220;Innovative optical tools for proximal sensing of ecophysiological processes&#8222; (OPTIMISE, ES1309; https://optimise.dcs.aber.ac.uk/) has produced three manuscripts addressing the main current challenges in this field. This article provides a framework to model the impact of different instrument noise and bias on the retrieval of SIF; and to assess uncertainty requirements for the calibration and characterization of state-of-the-art SIF-oriented spectroradiometers. We developed a sensor simulator capable of reproducing biases and noises usually found in field spectroradiometers. First the sensor simulator was calibrated and characterized using synthetic datasets of known uncertainties defined from laboratory measurements and literature. Secondly, we used the sensor simulator and the characterized sensor models to simulate the acquisition of atmospheric and vegetation radiances from a synthetic dataset. Each of the sensor models predicted biases with propagated uncertainties that modified the simulated measurements as a function of different factors. Finally, the impact of each sensor model on SIF retrieval was analyzed. Results show that SIF retrieval can be significantly affected in situations where reflectance factors are barely modified. SIF errors were found to correlate with drivers of instrumental-induced biases which are as also drivers of plant physiology. This jeopardizes not only the retrieval of SIF, but also the understanding of its relationship with vegetation function, the study of diel and seasonal cycles and the validation of remote sensing SIF products. Further work is needed to determine the optimal requirements in terms of sensor design, characterization and signal correction for SIF retrieval by proximal sensing. In addition, evaluation/validation methods to characterize and correct instrumental responses should be developed and used to test sensors performance in operational conditions

Study of reinforcement distribution, adhesion between layers, and porosity induced by FDM

This study aims to understand the distribution of reinforcement material in the matrix, evaluate the adherence between layers, and determine the air gap between printing roads. We printed the specimen with two different composite materials, Polylactic Acid (PLA) reinforced with acrylic particles, and another filament reinforced with short carbon fibers. For the observations of the samples, we used a Confocal Microscope. We estimated the porosity of the material by comparing the expected mass with that achieved after manufacture. By pixel count, after binarization, we found the average percentage of acrylate particulate. They showed fair distribution through the PLA matrix even after the manufacturing process. The determination of fibers alignment was made by binarization of image, together with k-means and edge detection. This combination of methods allows estimating the fiber alignment by orientation straight lines. The manufacturing process did not offer good alignment of the fibers, even with the filament initially well aligned

Sun-Induced Chlorophyll Fluorescence I: Instrumental Considerations for Proximal Spectroradiometers

Growing interest in the proximal sensing of sun‐induced chlorophyll fluorescence (SIF) has been boosted by space-based retrievals and up-coming missions such as the FLuorescence EXplorer (FLEX). The European COST Action ES1309 “Innovative optical tools for proximal sensing of ecophysiological processes” (OPTIMISE, ES1309; https://optimise.dcs.aber.ac.uk/) has produced three manuscripts addressing the main current challenges in this field. This article provides a framework to model the impact of different instrument noise and bias on the retrieval of SIF; and to assess uncertainty requirements for the calibration and characterization of state-of-the-art SIF-oriented spectroradiometers. We developed a sensor simulator capable of reproducing biases and noises usually found in field spectroradiometers. First the sensor simulator was calibrated and characterized using synthetic datasets of known uncertainties defined from laboratory measurements and literature. Secondly, we used the sensor simulator and the characterized sensor models to simulate the acquisition of atmospheric and vegetation radiances from a synthetic dataset. Each of the sensor models predicted biases with propagated uncertainties that modified the simulated measurements as a function of different factors. Finally, the impact of each sensor model on SIF retrieval was analyzed. Results show that SIF retrieval can be significantly affected in situations where reflectance factors are barely modified. SIF errors were found to correlate with drivers of instrumental-induced biases which are as also drivers of plant physiology. This jeopardizes not only the retrieval of SIF, but also the understanding of its relationship with vegetation function, the study of diel and seasonal cycles and the validation of remote sensing SIF products. Further work is needed to determine the optimal requirements in terms of sensor design, characterization and signal correction for SIF retrieval by proximal sensing. In addition, evaluation/validation methods to characterize and correct instrumental responses should be developed and used to test sensors performance in operational conditions