We introduce a new catchment dataset for large-sample
hydrological studies in Brazil. This dataset encompasses daily time series
of observed streamflow from 3679 gauges, as well as meteorological ...forcing
(precipitation, evapotranspiration, and temperature) for 897 selected
catchments. It also includes 65 attributes covering a range of topographic,
climatic, hydrologic, land cover, geologic, soil, and human intervention
variables, as well as data quality indicators. This paper describes how the
hydrometeorological time series and attributes were produced, their primary
limitations, and their main spatial features. To facilitate comparisons with
catchments from other countries, the data follow the same standards as the
previous CAMELS (Catchment Attributes and MEteorology for Large-sample
Studies) datasets for the United States, Chile, and Great Britain. CAMELS-BR (Brazil)
complements the other CAMELS datasets by providing data for hundreds of
catchments in the tropics and the Amazon rainforest. Importantly,
precipitation and evapotranspiration uncertainties are assessed using
several gridded products, and quantitative estimates of water consumption are
provided to characterize human impacts on water resources. By extracting and
combining data from these different data products and making CAMELS-BR
publicly available, we aim to create new opportunities for hydrological
research in Brazil and facilitate the inclusion of Brazilian basins in
continental to global large-sample studies. We envision that this dataset
will enable the community to gain new insights into the drivers of
hydrological behavior, better characterize extreme hydroclimatic events, and
explore the impacts of climate change and human activities on water
resources in Brazil. The CAMELS-BR dataset is freely available at
https://doi.org/10.5281/zenodo.3709337 (Chagas et al., 2020).
We propose a novel M-estimate conjugate gradient (CG) algorithm, termed Tukey's biweight M-estimate CG (TbMCG), for system identification in impulsive noise environments. In particular, the TbMCG ...algorithm can achieve a faster convergence while retaining a reduced computational complexity as compared to the recursive least-squares (RLS) algorithm. Specifically, the Tukey's biweight M-estimate incorporates a constraint into the CG filter to tackle impulsive noise environments. Moreover, the convergence behavior of the TbMCG algorithm is analyzed. Simulation results confirm the excellent performance of the proposed TbMCG algorithm for system identification and active noise control applications.
Lacerda, LT, Marra-Lopes, RO, Diniz, RCR, Lima, FV, Rodrigues, SA, Martins-Costa, HC, Bemben, MG, and Chagas, MH. Is performing repetitions to failure less important than volume for muscle ...hypertrophy and strength? J Strength Cond Res 34(5): 1237-1248, 2020-The aim of this study was to investigate the effects of muscle failure (MF) or not to MF (NMF) training on strength and muscle hypertrophy relative gains (average and individual data). Ten men untrained in resistance training participated in the study. Each leg was allocated in 1 of 2 unilateral training protocols (MF or NMF with equal volume) on knee extension exercise. Both protocols were performed with 3-4 sets, 3 minutes' rest, and 55-60% of one repetition maximum (1RM). Rectus femoris and vastus lateralis muscles cross-sectional area (CSA), maximal muscle strength (1RM and maximal voluntary isometric contraction), and muscular endurance (maximum number of repetition) were assessed before and after 14 weeks. In addition, neuromuscular activation by normalized root mean square of the electromyographic signal (EMGRMS) was measured in 2nd and 35th training sessions. The average results showed that both training protocols were similarly effective in inducing increases in strength and muscle hypertrophy gains. However, individual analysis data suggest that NMF protocol with equal volume may promote similar or even greater muscle hypertrophy (vastus lateralis) and muscular endurance performance when compared with MF protocol. Also, normalized EMGRMS responses analyzed during 2nd and 35th sessions were similar in MF and NMF protocols for rectus femoris and vastus lateralis muscles. In conclusion, MF and NMF protocol conducted with the same total repetition numbers produced similar maximal muscle strength performance and neuromuscular activation. Nevertheless, NMF training could be a more appropriate strategy to increase muscle hypertrophy (vastus lateralis) and muscular endurance performance in untrained individuals when compared with MF.
This paper studies the hydromechanical behavior of a slightly compacted mixture of sand and clayey silt (30%/70%) under a generalized stress state. The experimental study focused on analyzing the ...yielding response and shear strength behavior at different stress states (characterized by the intermediate principal stress parameter b, or Lode angle) and at different initial total suctions (as-compacted state). For the investigation, a hollow cylinder apparatus was used. The shear strength results allowed defining the variation of the critical state line with the Lode angle and the suction. Different models were proposed for isotropic and anisotropic yield surfaces, and their shape and rotation were calibrated with experimental results. The modeled yield surfaces fitted reasonably well the experimental results, considering their inclination and dependence on the suction, mean and deviatoric stresses, and Lode angle. In addition, some relationships between the stresses and the model parameters were proposed to normalize the yield surface equation.
Microbes present in the rumen of dairy cows are essential for degradation of cellulosic and nonstructural carbohydrates of plant origin. The prepartum and postpartum diets of high-producing dairy ...cows are substantially different, but in what ways the rumen microbiome changes in response and how those changes may influence production traits are not well elucidated. Here, we sequenced the 16S and 18S rRNA genes using the MiSeq platform to characterize the prepartum and postpartum rumen fluid microbiomes in 115 high-producing dairy cows, including both primiparous and multiparous animals. Discriminant analysis identified differences between the microbiomes of prepartum and postpartum samples and between primiparous and multiparous cows. 18S rRNA sequencing revealed an overwhelming dominance of the protozoan class Litostomatea, with over 90% of the eukaryotic microbial population belonging to that group. Additionally, fungi were relatively more prevalent and Litostomatea relatively less prevalent in prepartum samples than in postpartum ones. The core rumen microbiome (common to all samples) consisted of 64 bacterial taxa, of which members of the genus Prevotella were the most prevalent. The Chao1 richness index was greater for prepartum multiparous cows than for postpartum multiparous cows. Multivariable models identified bacterial taxa associated with increased or reduced milk production, and general linear models revealed that a metagenomically based prediction of productivity is highly associated with production of actual milk and milk components. In conclusion, the structure of the rumen fluid microbiome shifts between the prepartum and first-week postpartum periods, and its profile within the context of this study could be used to accurately predict production traits.
High-order spectral element methods (SEM) for large-eddy simulation (LES) are still very limited in industry. One of the main reasons behind this is the lack of robustness of SEM for under-resolved ...simulations, which can lead to the failure of the computation or to inaccurate results, aspects that are critical in an industrial setting. To help address this issue, we introduce a non-modal analysis technique that characterizes the numerical diffusion properties of spectral element methods for linear convection–diffusion problems, including the scales affected by numerical diffusion and the relationship between the amount of numerical diffusion and the level of under-resolution in the simulation. This framework differs from traditional eigenanalysis techniques in that all eigenmodes are taken into account with no need to differentiate them as physical or unphysical. While strictly speaking only valid for linear problems, the non-modal analysis is devised so that it can give critical insights for under-resolved nonlinear problems. For example, why do SEM sometimes suffer from numerical stability issues in LES? And, why do they at other times be robust and successfully predict under-resolved turbulent flows even without a subgrid-scale model? The answer to these questions in turn provides crucial guidelines to construct more robust and accurate schemes for LES.
For illustration purposes, the non-modal analysis is applied to the hybridized discontinuous Galerkin methods as representatives of SEM. The effects of the polynomial order, the upwinding parameter and the Péclet number on the so-called short-term diffusion of the scheme are investigated. From a non-modal analysis point of view, and for the particular case of hybridized discontinuous Galerkin methods, polynomial orders between 2 and 4 with standard upwinding are found to be well suited for under-resolved turbulence simulations. For lower polynomial orders, diffusion is introduced in scales that are much larger than the grid resolution. For higher polynomial orders, as well as for strong under/over-upwinding, robustness issues can be expected due to low and non-monotonic numerical diffusion. The non-modal analysis results are tested against under-resolved turbulence simulations of the Burgers, Euler and Navier–Stokes equations. While devised in the linear setting, non-modal analysis successfully predicts the behavior of the scheme in the nonlinear problems considered. Although the focus of this paper is on LES, the non-modal analysis can be applied to other simulation fields characterized by under-resolved scales.
•Introduced non-modal analysis to assess dissipation of spectral element methods (SEM).•Non-modal analysis shows excellent agreement with large-eddy simulation results.•Non-monotonic dissipation in wavenumber space may lead to numerical stability issues.•Numerical dissipation in discontinuous SEM resembles a subgrid-scale model.•Moderately high orders in discontinuous SEM seem best for large-eddy simulation.
The enrichment of P in surface waters has been linked to P runoff from agricultural fields amended with fertilizers. Novel slow‐release mineral fertilizers, such as struvite and P‐exchanged layered ...double hydroxides (LDHs), have received increasing attention for P recycling from waste streams, and these fertilizers may potentially reduce the risk of runoff losses. Here, a rainfall simulation experiment was performed to evaluate P runoff associated with the application of recycled slow‐release fertilizers relative to that of a soluble fertilizer. Monoammonium phosphate (MAP), struvite, and LDH granular fertilizers were broadcasted at equal total P doses on soil packed in trays (5% slope) and covered with perennial ryegrass (Lolium perenne L.). Four rainfall simulation events of 30 min were performed at 1, 5, 15, and 30 d after the fertilizer application. Runoff water from the trays was collected, filtered, and analyzed for dissolved P. For the MAP treatment, P runoff losses were high in the first two rain events and leveled off in later rain events. In total, 42% of the applied P in the MAP treatment was lost due to runoff. In the slow‐release fertilizer treatments, P runoff losses were limited to 1.9 (struvite) and 2.4% (LDH) of the applied doses and were more similar over the different rain events. The use of these novel P fertilizer forms could be beneficial in areas with a high risk of surface water eutrophication and a history of intensive fertilization.
Core Ideas
Granular struvite and LDH are known as slow‐release fertilizers (SRFs).
For the first time, struvite and LDH were tested in a runoff experiment.
42% of P in the MAP treatment was lost as DP due to runoff.
Struvite and LDH showed much lower loss (<3% of applied P) than MAP.
Applying SRFs can be considered in areas and times with a high risk of eutrophication.
An efficient, accurate, and reliable approximation of a matrix by one of lower rank is a fundamental task in numerical linear algebra and signal processing applications. In this paper, we introduce a ...new matrix decomposition approach termed subspace-orbit randomized singular value decomposition (SOR-SVD), which makes use of random sampling techniques to give a low-rank approximation to an input matrix. Given a large and dense data matrix of size <inline-formula><tex-math notation="LaTeX">m\times n</tex-math></inline-formula>, the algorithm requires a few passes through data to compute a rank-<inline-formula><tex-math notation="LaTeX">k</tex-math></inline-formula> approximation in <inline-formula><tex-math notation="LaTeX">O(mnk)</tex-math></inline-formula> floating-point operations. Moreover, the SOR-SVD algorithm can utilize advanced computer architectures and, as a result, it can be optimized for maximum efficiency. The SOR-SVD algorithm is simple, accurate, and provably correct, and outperforms previously reported techniques in terms of accuracy and efficiency. Our numerical experiments support these claims.
In this work, a simple and effective robust adaptive beamforming technique is proposed for uniform linear arrays, which is based on the power spectral estimation and uncertainty region (PSEUR) of the ...interference plus noise (IPN) components. In particular, two algorithms are presented to find the angular sector of interference in every snapshot based on the adopted spatial uncertainty region of the interference direction. Moreover, a power spectrum is introduced based on the estimation of the power of interference and noise components, which allows the development of a robust approach to IPN covariance matrix reconstruction. The proposed method has two main advantages. First, an angular region that contains the interference direction is updated based on the statistics of the array data. Second, the proposed IPN-PSEUR method avoids estimating the power spectrum of the whole range of possible directions of the interference sector. Simulation results show that the performance of the proposed IPN-PSEUR beamformer is almost always close to the optimal value across a wide range of signal-to-noise ratios.
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