Detecting trends in flow and precipitation series has great importance for the management of water resources and can be accomplished using statistic non-parametric tests. This work evaluated the significance of trends in flow and temporal series of precipitation as well as monthly and annual precipitation trends using Pettitt's test. The study used historical
Proximal sensing for assessing sugarcane quality information during harvest can be affected by various factors, including the type of sample preparation. The objective of this study was to determine the best sugarcane sample type and analyze the spectral response for the prediction of quality parameters of sugarcane from visible and near-infrared (vis-NIR) spectroscopy. The sampling and spectral data acquisition were performed during the analysis of samples by conventional methods in a sugar mill laboratory. Samples of billets were collected and four modes of scanning and sample preparation were evaluated: outer-surface (‘skin’) (SS), cross-sectional scanning (CSS), defibrated cane (DF), and raw juice (RJ) to analyze the parameters soluble solids content (Brix), saccharose (Pol), fibre, pol of cane and total recoverable sugars (TRS). Predictive models based on Partial Least Square Regression (PLSR) were built with the vis-NIR spectral measurements. There was no significant difference (p-value > 0.05) between the accuracy SS and CSS samples compared to DF and RJ samples for all prediction models. However, DF samples presented the best predictive performance values for the main sugarcane quality parameters, and required only minimal sample preparation. The results contribute to advancing the development of on-board quality monitoring in sugarcane, indicating better sampling strategies.
Studies involving the use of microalgae are increasingly intensifying for the potential they present to produce biofuels, because they are a renewable energy source that does not compete directly with food production, and because they enable the obtaining of a fuel with less environmental impact when compared to fossil fuel. In this context, the use of microalgae is directly associated to its capacity to be produced on a large scale and to be extracted from the culture medium. Rheological studies are important for obtaining the information needed in the elaboration of projects and equipment that will be used in various operations existing in systems of production and extraction of algal biomass. In the evaluation of different levels of dry biomass concentration, studies have been conducted of the rheological behavior of cultures of Chlorella sp. BR001 and Scenedesmus sp. BR003. The Power Law model adjusted well to the data of shear stress as a function of strain rate. In all concentrations the cultures showed non-Newtonian behavior. It was observed to Scenedesmus sp. BR003 little effect of biomass concentration on the apparent viscosity and shear stress.KEYWORDS: microalgae, biomass, production, operation. COMPORTAMENTO REOLÓGICO DE CULTIVOS DE Chlorella sp. E Scenedesmus sp.EM DIFERENTES CONCENTRAÇÕES DE BIOMASSA RESUMO: Estudos envolvendo o uso de microalgas cada vez mais se intensificam, pelo potencial que apresentam para a produção de biocombustíveis, por ser uma fonte de energia renovável que não compete diretamente com a produção de alimentos e por possibilitar a obtenção de um combustível com menor impacto ambiental quando comparado ao combustível fóssil. Neste contexto, a utilização de microalgas está diretamente associada à sua capacidade de ser produzida em larga escala e de ser extraída do meio de cultivo. Os estudos reológicos são importantes para a obtenção das informações necessárias na elaboração dos projetos e dos equipamentos que serão utilizados nas diversas operações existentes nos sistemas de produção e de extração da biomassa algal. Na avaliação de diferentes níveis de concentração de biomassa seca, foram realizados estudos do comportamento reológico de cultivos de Chlorella sp. BR001 e Scenedesmus sp. BR003. O modelo de Lei de Potência ajustou bem aos dados de tensão de cisalhamento em função da taxa de deformação. Em todas as concentrações, os cultivos apresentaram comportamento não newtoniano. Verificou-se para Scenedesmus sp. BR003 pouco efeito da concentração de biomassa na viscosidade aparente e na tensão de cisalhamento. PALAVRAS-CHAVE:microalgas, biomassa, produção, operação.
Spatial variability evaluation of qualitative attributes can be used as an excellent strategy to design forms of intervention that result in better crop profitability for some agricultural crops, for example, sugarcane. Based on the assumption that qualitative attributes of sugarcane present spatial variability and their distributions along the stems are uniform in different varieties, this study aimed to evaluate the distributions of the qualitative parameters of different sugarcane varieties and the spatial variability of these attributes in a commercial field. Samples of nine varieties were collected for laboratory quality analysis, and the Brix parameter was analyzed by a digital refractometer. The analysis of variance, the Tukey test, and geoestatistcs were the statistical analyses applied to the dataset. The maps were generated using 91 sample results from the laboratory analysis of the 16.6 ha field. It was found that, in the harvest period, there was no significant difference in Brix content along the sugarcane stems. Therefore, we can conclude that the Brix content along the sugarcane stems does not change in the harvesting period, and the ideal sampling size to better represent the factors affecting sugarcane qualitative attributes is six points per hectare.
The use of optical sensors to identify the nutritional needs of agricultural crops has been the subject of several studies using precision agriculture techniques. In this work, we sought to overcome the lack of research evaluating the use of these techniques in the management of nitrogen (N) fertilizer in pastures. We evaluated the methodology of the nitrogen sufficiency index (NSI) in N management at variable rates (VR) using a portable chlorophyll meter. In addition, the use of color vegetation indices generated from a digital camera was evaluated as a low-cost alternative. The work was conducted in four management cycles at different times of year, evaluating the productivity and quality of Brachiaria brizantha cv. Xaraés grass. Three NSIs (0.85, 0.90 and 0.95) were evaluated, applying complementary doses of N according to the response of monitored plots using a chlorophyll meter and comparing the productivity and leaf N content of these treatments to the reference treatment (TREF), which received a single dose of N (150 kg ha-1). Together with these treatments, plots without N application (control) were analyzed, totaling five treatments with six replications in a completely randomized design. The dry mass productivity and N leaf concentration of the VR treatments were statistically equal to TREF in all management cycles (P < 0.05). Most color vegetation indices correlated significantly (P < 0.05) to the chlorophyll readings. The use of NSI methodology in pastures allows the same productivity gains, with significant input savings. In addition, the use of digital cameras presents itself as a viable alternative to monitoring the N status in pastures.
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