À descoberta de sofware para explorar a programação linear no ensino secundário

A Programação Linear, PL, tem como objectivo a resolução de problemas de optimização com restrições em que todas as funções envolvidas são lineares. Diversos problemas da vida real podem ser formulados como problemas de PL como, por exemplo, os problemas de planeamento e de transportes. A Programação Linear é um dos temas obrigatórios de algumas disciplinas de Matemática do Ensino Secundário, sendo importante que se trabalhem com os alunos problemas que traduzam situações reais, ou suas adaptações. Como estes problemas nem sempre são fáceis e rápidos de resolver, a utilização de ferramentas tecnológicas na sua resolução reveste-se de enorme importância. Existem diversos programas de computador como o Solver do Microsoft Office Excel, o WinQSB, o Programación Lineal e o Winplot, de fácil utilização pelos alunos, que possibilitam a exploração gráfica, no caso bidimensional, ou analítica dos problemas de PL. O uso deste software permite que os alunos resolvam uma maior diversidade de problemas e se centrem mais na análise e interpretação de resultados. Neste artigo, ilustra-se, resumidamente, a forma de resolver problemas de PL com o software mencionado e discute-se as suas potencialidades e limitações

Linear programming knowledge in first stage higher education courses

In this work we will describe an experimental study with approximately fifty Portuguese students of the 2nd year of the BSc Degree of Biomedical Engineering as well as Chemical and Biological Engineering Higher Education Courses. The aims of this study are to identify which knowledge of Linear Programming (LP) taught in High School the students acquired and still remember, which tools they used in that stage of education when learning the theme of LP and their opinion about the significance of LP in daily life problem resolution. We also propose to investigate if the students are able to use WinQSB software to solve LP problems. In addition, we intend to identify not only the versatility of this software but also the opinion of the students about the resolution of LP problems with WinQSB, as well as their main difficulties during this experience

Modeling Aerosol-Cloud-Precipitation Interactions in Mountainous Regions: Challenges in the Representation of Indirect Microphysical Effects with Impacts at Subregional Scales

In mountainous regions, the nonlinear thermodynamics of orographic land-atmosphere interactions (LATMI) in organizing and maintaining moisture convergence patterns on the one hand, and aerosol-cloud-precipitation interactions (ACPI) in modulating the vertical structure of precipitation and space-time variability of surface precipitation on the other, are difficult to separate unambiguously because the physiochemical characteristics of aerosols themselves exhibit large sub-regional scale variability. In this chapter, ACPI in the Central Himalayas are examined in detail using aerosol observations during JAMEX09 (Joint Aerosol Monsoon Campaign 2009) to specify CCN activation properties for simulations of a premonsoon convective storm using the Weather Research and Forecasting (WRF) version 3.8.1. The focus is on contrasting AIE during episodes of remote pollution run-up from the Indo-Gangetic Plains and when only local aerosols are present in Central Nepal. This study suggests strong coupling between the vertical structure of convection in complex terrain that governs the time-scales and spatial organization of cloud development, CCN activation rates, and cold microphysics (e.g. graupel production is favored by slower activation spectra) that result in large shifts in the spatial distribution of precipitation, precipitation intensity and storm arrival time

Toward a Physical Characterization of Raindrop Collision Outcome Regimes

A comprehensive raindrop collision outcome regime diagram that delineates the physical conditions associated with the outcome regimes (i.e., bounce, coalescence, and different breakup types) of binary raindrop collisions is proposed. The proposed diagram builds on a theoretical regime diagram defined in the phase space of collision Weber numbers We and the drop diameter ratio p by including critical angle of impact considerations. In this study, the theoretical regime diagram is first evaluated against a comprehensive dataset for drop collision experiments representative of raindrop collisions in nature. Subsequently, the theoretical regime diagram is modified to explicitly describe the dominant regimes of raindrop interactions in (We, p) by delineating the physical conditions necessary for the occurrence of distinct types of collision-induced breakup (neck/filament, sheet, disk, and crown breakups) based on critical angle of impact consideration. Crown breakup is a subtype of disk breakup for lower collision kinetic energy that presents distinctive morphology. Finally, the experimental results are analyzed in the context of the comprehensive collision regime diagram, and conditional probabilities that can be used in the parameterization of breakup kernels in stochastic models of raindrop dynamics are provided

Optimization of raw ewes’ milk high-pressure pre-treatment for improved production of raw milk cheese

Serra da Estrela protected designation of origin (PDO) cheese is manufactured with raw milk from Bordaleira and/or Churra Mondegueira da Serra da Estrela sheep breeds. Several socioenvironmental shortcomings have reduced production capacity; hence, treatments that may contribute to its efficient transformation into cheese are welcome. High-pressure processing (HPP) milk pre-treatment may contribute to a cheese yield increment, yet optimization of processing conditions is warranted. An initial wide-scope screening experiment allowed for pinpointing pressure intensity, holding time under pressure and time after HPP as the most important factors influencing curd yield. Based on this, a more targeted screening experiment allowed for selecting the range of experimental conditions to be used for an experimental design study that revealed an HPP treatment at 121 MPa for 30 min as the optimum for milk processing to improve curd yield (>9%) and effectively maintain the beneficial cheese microbiota; the optimum was validated in a final experimental framework.info:eu-repo/semantics/publishedVersio

Experimental and numerical analysis of continuous RC slab strips strengthened with CFRP laminates by using the NSM technique

Os programas experimentais para o reforço à flexão de estruturas de concreto armado (CA) segundo a técnica NSM (Near Surface Mounted, em língua inglesa) com laminados de fibras de carbono (CFRP) são, em geral, realizados com vigas simplesmente apoiadas. Deste modo, há uma carência de estudos experimentais e teóricos sobre a redistribuição de momentos em elementos estruturais estaticamente indeterminados reforçados segundo a técnica NSM. Assim, de forma a avaliar a influência da técnica de reforço NSM no incremento de capacidade de carga e na redistribuição de momentos em elementos contínuos de CA, um programa experimental composto por dezessete faixas de laje foi realizado, onde seis faixas de lajes foram ensaiadas sem qualquer tipo de reforço compósito (SL15-H/HS, SL30-H/HS e SL45-H/HS), formando o conjunto de lajes de referência, e onze faixas de laje (SL15s25-H/HS, SL15s50-H, SL30s25-H/HS, SL30s50-H/HS, SL45s25-H/HS e SL45s50-H/HS) foram reforçadas com laminados de CFRP inseridos no concreto de recobrimento segundo a técnica NSM. Para fins de validação, os resultados experimentais são comparados com os valores previstos pela análise efetuada com um programa de cálculo automático baseado no método dos elementos finitos (MEF). Por fim, um estudo paramétrico composto por 288 modelos numéricos foi realizado para investigar a influência da configuração de reforço e da percentagem de CFRP no incremento da capacidade de carga e da redistribuição de momentos em faixas de lajes reforçadas segundo a técnica NSM. Os programas experimental e numérico referentes às faixas de laje das séries SL15-H/HS são descritos e os resultados obtidos são apresentados e analisados neste trabalho.The experimental programs for the flexural strengthening of reinforced concrete (RC) structures using the Near Surface Mounted (NSM) technique with Carbon Fiber Reinforced Polymer (CFRP) laminates were, in general, conducted with simply supported beams. Therefore, there is a lack of experimental and theoretical studies on the moment redistribution of statically indeterminate RC elements strengthened with NSM technique. Thus, in order to assess the influence of the NSM CFRP flexural strengthening technique on the increase of the load carrying capacity and the moment redistribution capacity of continuous RC elements, an experimental composed of seventeen RC slab strips was carried out, in which six of the RC slabs were unstrengthened, forming a control set (SL15-H/HS, SL30-H/HS and SL45-H/HS), and eleven slabs (SL15s25-H/HS, SL15s50-H, SL30s25-H/HS, SL30s50-H/HS, SL45s25-H/HS and SL45s50-H/HS) were strengthened with CFRP laminates according to the NSM technique. Furthermore, for validation purposes, the experimental results are compared with values predicted by the analysis carried out using a FEM-based computer program. Finally, a parametric study composed of 288 numerical models is carried out to investigate the influence of the strengthening arrangement and CFRP percentage in terms of load carrying capacity and moment redistribution capacity of continuous RC slab strips flexurally strengthened by the NSM technique. The experimental and numerical programs concerns to the SL15-H/HS Series are described and the obtained results are presented and analyzed in this paper

Probable maximum precipitation estimation using multifractals: Application in the eastern united states

ABSTRACT Probable maximum precipitation (PMP) is the conceptual construct that defines the magnitude of extreme storms used in the design of dams and reservoirs. In this study, the value and utility of applying multifractal analysis techniques to systematically calculate physically meaningful estimates of maximum precipitation from observations in the eastern United States is assessed. The multifractal approach is advantageous because it provides a formal framework to infer the magnitude of extreme events independent of empirical adjustments, which is called the fractal maximum precipitation (FMP), as well as an objective estimate of the associated risk. Specifically, multifractal (multiscaling) behavior of maximum accumulated precipitation at daily (327 rain gauges) and monthly (1400 rain gauges) timescales, as well as maximum accumulated 6-hourly precipitable water fluxes for the period from 1950 to 1997 were characterized. Return periods for the 3-day FMP estimates in this study ranged from 5300 to 6200 yr. The multifractal parameters were used to infer the magnitude of extreme precipitation consistent with engineering design criterion (e.g., return periods of 10 6 yr), the design probable maximum precipitation (DPMP). The FMP and DPMP were compared against PMP estimates for small dams in Pennsylvania using the standard methodology in engineering practice (e.g., National Weather Service Hydrometeorological Reports 51 and 52). The FMP estimates were usually, but not always, found to be lower than the standard PMP (FMP/PMP ratios ranged from 0.5 to 1.0). Furthermore, a high degree of spatial variability in these ratios points to the importance of orographic effects locally, and the need for place-based FMP estimates. DMP/PMP ratios were usually greater than one (0.96 to 2.0), thus suggesting that DPMP estimates can provide a bound of known risk to the standard PMP

Drought response of cowpea (Vigna unguiculata (L.) Walp.) landraces at leaf physiological and metabolite profile levels

Drought threatens the world’s food production, particularly in Sub Saharan Africa low external input and rain fed agricultural systems, where cowpea (Vigna unguiculata (L.) Walp.) is an important food crop. In the context of growing concerns regarding climate changes implications on water availability, this study aimed at 1) to evaluate the drought responses in cowpea landraces with contrasting drought tolerance levels (A55 – high sensitivity; A80 - mild sensitivity; A116 - tolerant), 2) using an integrated physiological (leaf gas exchanges; chlorophyll a fluorescence) and biochemical (photoprotective pigments; RuBisCO activity; primary metabolite profiling) analysis to identify drought tolerance probes, in plants submitted to three water availability levels (well-watered, WW; mild drought, MD; severe drought, SD). A116 plants maintained a better water status under drought, what could justify the higher Pn and Pnmax values in MD, as well as higher photochemical use of energy (reflected in the photochemical quenching (qL) and in the quantum yield of non-cyclic electron transport (Y(II))), and the lower need of photoprotective thermal dissipation mechanisms (given by the non-photochemical quenching (qN), and the quantum yield of regulated energy dissipation at photosystem PSII (Y(NPQ))), in MD and SD plants. Greater declines of net (Pn) and potential (Pnmax) photosynthesis were observed in A55 plants, which frequently showed significant impacts already under MD conditions in most parameters, whereas A80 usually displayed and intermediate behaviour. Still, even A55 showed some acclimation response, regarding photoprotective mechanisms associated with high contents of zeaxanthin, lutein, and carotenes, and high Y(NPQ), and qN values, supporting the absence of an increase in the non-regulated energy dissipation at PSII (Y(NO) did not increased) even in SD plants. Additionally, A55 was not significantly affected in RuBisCO activity, which showed to be quite resilient in cowpea. A primary metabolite profiling, complemented with a partial least square discrimination analysis (PLS-DA), allowed a better separation of A116 and A55 plants according to their degree of drought tolerance. In response to drought, A116 showed the greatest accumulation of most responsive metabolites, 14 in total, with sucrose, fucose, urea, alanine and putrescine being exclusively increased in this genotype, suggesting that they can be candidates as drought tolerance proxies. Other compounds, as proline, valine, isoleucine (among amino acids), and rhamnose and raffinose (among sugars) showed close increase patternsinfo:eu-repo/semantics/publishedVersio