196 resultados para hydroelectric power and aquatic macrophytes


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The aim of this study was to verify the correlation between the Wingate arm crank test outputs (peak power, mean power, and fatigue index), obtained on a specific ergometer, and the performance in crawl stroke swim sprints of 14, 25, 50, and 400 m. The experiment was conducted with 9 healthy male volunteers (18.1 ± 2.2 years of age; 172 ± 0.04 cm; 67.7 ± 5.92 kg and 15.7 ± 4.57% body fat). On determined days, all individuals were submitted to the Wingate arm crank test and crawl freestyle sprints of 14, 25, 50, and 400 m as they were timed with a stopwatch. The peak power, the mean power, and the fatigue index, which were obtained during the Wingate arm crank test, were not significantly correlated with the maximum swim velocities during the crawl freestyle tests of 14 (r = 0.40; r = 0.64; r = 0.11), 25 (r = 0.28; r = 0.39; r = -0.17), 50 (r = 0.03; r = 0.09; r = -0.31), and 400 (r = -0.52; r = -0.37; r = -0.65) m, respectively. Thus, it is possible to conclude that the Wingate arm crank test is not suitable to assess the anaerobic power of swimmers under the described experimental conditions.

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The project is being conducted in the town of Analândia, São Paulo, Brazil. The constructed wetlands system for water supply consists of a channel with floating aquatic macrophytes, HDS system (Water Decontamination with Soil - Patent PI 850.3030), chlorinating system, filtering system and distribution. The project objectives include investigating the process variables to further optimize design and operation factors, evaluating the relation of nutrients and plants development, biomass production, shoot development, nutrient cycling and total and fecal coliforms removal, comparing the treatment efficiency among the seasons of the year; and moreover to compare the average values obtained between February and June 1998 (Salati et al., 1998) with the average obtained for the same parameters between March and June 2000. Studies have been developed in order to verify during one year the drinking quality of the water for the following parameters: turbidity, color, pH, dissolved oxygen, total of dissolved solids, COD, chloride, among others, according to the Ministry of Health's Regulation 36. This system of water supply projected to treat 15 L s-1 has been in continuous operation for 2 years, it was implemented with support of the National Environment Fund (FNMA), administered by the Center of Environmental Studies (CEA-UNESP), while the technical supervision and design were performed by the Institute of Applied Ecology. The actual research project is being supported by FAPESP.

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The aim of this study was to evaluate the nutritive value of free-floating aquatic macrophytes, Eichhornia crassipes (Mart.) Solms (Pontederiaceae), Pistia stratiotes (L.) (Araceae) and Salvinia molesta (Mitchell) (Salviniaceae) used in a Nile tilapia (Oreochromis niloticus) waste treatment, and these species biomass potential uses. The vegetal biomass samples were collected from 0.25 m 2 floating squares and divided in aerial and submerse parts, to determine the concentrations of cell wall fraction, soluble carbohydrates, polyphenols, lipids, crude protein and total phosphorus. The higher nutritive value was observed in E. crassipes and S. molesta aerial parts, and in P. stratiotes total biomass, due to their lower cell wall fraction mean rates (60.7; 64.2 and 56.9 % dry mass, respectively) and to the higher rates of: crude protein (10.1; 9.1 and 8.8 % dry mass, respectively), soluble carbohydrates (26.6; 18.7 and 12.4 mg.g -1 dry mass, respectively) and lipids (7.6; 4.5 and 4.4% dry mass, respectively). It may be concluded that P. stratiotes total biomass, and E. crassipes and S. molesta aerial biomass have nutritive values with potential use for ruminant feeding or as ration ingredients.

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The problem of power system stability including the effects of a flexible alternating current transmission system (FACTS) is approached. First, the controlled series compensation is considered in the machine against infinite bar system and its effects are taken into account by means of construction of a Lyapunov function (LF). This simple system is helpful in order to understand the form the device affects dynamic and transient performance of the power system. After, the multimachine case is considered and it is shown that the single-machine results apply to multimachine systems. An energy-form Lyapunov function is derived for the power system including the FACTS device and it is used to analyse damping and synchronizing effects due to the FACTS device in single-machine as well as in multimachine power systems. © 2005 Elsevier Ltd. All rights reserved.

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This paper discusses the utilization of Virtual Instrumentation to the implementation and evaluation of different power definitions, so that classical formulations and new definitions can be compared without the necessity of acquiring different power meters or analyzers. Accordingly, the definitions of IEEE Standard 1459-2000 for the measurement of power quantities under distorted and unbalanced situations, have been digitally implemented. Thus, several power and power factor components related to the decomposition of the measured voltage and current signals have been obtained. The proposed PC-based Virtual Instrument uses a high performance acquisition board and isolated sensors and transducers. All digital algorithms and routines have been implemented by means of a graphical development system. Regarding to the implementation of STD 1459, this paper also proposes several different algorithms to the required decompositions of voltage, current and power components. © 2005 IEEE.

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In this report we investigate the optical properties and energy-transfer upconversion luminescence of Ho3+- and Tb3+/Yb 3+-codoped PbGeO3-PbF2-CdF2 glass-ceramic under infrared excitation. In Ho3+/Yb 3+-codoped sample, green(545 nm), red(652 nm), and near-infrared(754 nm) upconversion luminescence corresponding to the 4S 2(5F4) → 5I8, 5F5 → 5I8, and 4S2(5F4) → 5I 7, respectively, was readly observed. Blue(490 nm) signals assigned to the 5F2,3 → 5I8 transition was also detected. In the Tb3+/Yb3+ system, bright UV-visible emission around 384, 415, 438, 473-490, 545, 587, and 623 nm, identified as due to the 5D3(5G6) → 7FJ(J=6,5,4) and 5D4→ 7FJ(J=6,5,4,3) transitions, was measured. The comparison of the upconversion process in glass ceramic and its glassy precursor revealed that the former samples present much higher upconversion efficiencies. The dependence of the upconversion emission upon pump power, and doping contents was also examined. The results indicate that successive energy-transfer between ytterbium and holmium ions and cooperative energy-transfer between ytterbium and terbium ions followed by excited-state absorption are the dominant upconversion excitation mechanisms herein involved. The viability of using the samples for three-dimensional solid-state color displays is also discussed.

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In the Research and Teaching Farm of the State University of São Paulo (UNESP) - Campus of Ilha Solteira, located in Selviria, in Mato Grosso do Sul State, a study was conducted with the objective of investigating the resistance to penetration of a highly degraded soil due to construction of a Hydroelectric Power Plant. The experimental design was a completely randomized, with five treatments and five replications. The treatments were constituted of the following uses and managements: area in advanced state of degradation; area under regeneration cultivated 13 years with Pinus; area under regeneration cultivated 11 years with green manure and pasture; degraded area with natural regeneration; and area with natural vegetation (savanna). The system where the area was under regeneration with Pinus cultivation and the niches with natural regeneration were the closest to natural condition (savanna). Except for the natural area (savanna), all others presented a higher resistance to penetration in the layer of 0.20-0.40 m, which represents serious limitations for growth of plant roots.

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The structural and optical properties of nanocrystalline GaN and GaN:H films grown by RF-tnagnetron sputtering are focused here. The films were grown using a Ga target and a variety of deposition parameters (N 2/H 2/Arflow rates, RF power, and substrate temperatures). Si (100) and fused silica substrates were used at relatively low temperatures (T s ≤ 420K). The main effects resulting from the deposition parameters variations on the films properties were related to the presence of hydrogen in the plasma. The X-ray diffraction analysis indicates that the grain sizes (∼15nm) and the crystallized volume fraction significantly decrease when hydrogen is present in the plasma. The optical absorption experiments indicate that the hydrogenated films have absorption edges very similar to that of GaN single crystal films reported in the literature, while the non-hydrogenated samples present larger absorption tails encroaching into the gap energies.

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In the present work, aquatic humic substances (HS) were extracted by use of adsorbent XAD 8 and the acid humic fraction (AH) was separated throught acidification. After being purified by Hyphan resin and dialyze, the aquatic AH was characterized using Fourier-transform infrared spectroscopy and elemental analysis. The influence of the aquatic HA and electrolyte concentrations, pH and aquatic AH-metal complexation time on the conformation was investigated using UV/Vis spectroscopic studies, employing the equation suggested by Doty and Steiner. The results indicated that the acid humic flexible macromolecule assumes a condensed form at acid and alkaline pH. Other factors favoring condensed conformations are longer metal complexation time (ageing) and higher aquatic AH and electrolyte concentrations. Thus considering the strong influence of the investigated parameters in the structural conformation of the humic macromolecule, we conclude that studies using UV/Vis spectroscopy to estimate the concentration, aromaticity, humification degree of the aquatic AH and so on, require rigorous control over the experimental conditions employed to provide a correct interpretation of the analytical results. ©2006 Sociedade Brasileira de Química.

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Studies of the hemoglobin pattern in Brazilian reptiles are important for determining ecological and phylogenetic relationships, but they are scarce. Peripheral blood samples were obtained from 7 males and 18 females of Rhinoclemmys punctularia. The hematological profile was based on the total hemoglobin and hematocrit values. The hemoglobin profile was obtained using electrophoretic procedures at different pH, isoelectric focusing, globin chain electrophoresis, and HPLC. The hematocrit (31 ± 2%) and total hemoglobin (7.5 ± 0.2 g/dL) values did not indicate gender variations. Alkaline pH electrophoresis of the total blood samples treated with 1% saponin demonstrated the presence of four well-defined hemoglobin fractions, one major component (fraction I), showing cathodic migration and three others faster than fraction I with anodic migration. When the samples were precipitated with chloroform, only two hemoglobin fractions were observed, similar to fractions I and III from the first procedure. Isoelectric focusing and HPLC showed the same pattern. With acid and neutral pH electrophoresis, two fractions with anodic migration were observed. The globin chain identification at alkaline pH showed two fractions, but four fractions were observed at acidic pH, suggesting that different polypeptide chains are involved in the hemoglobin molecule. The chromatographic separation of the total blood sample demonstrated that the major fraction comprised 81.9% and the minor 18.1%. The results obtained demonstrated a similarity between these hemoglobin components and those of some Chelidae reported in the literature for both land and aquatic animals, reflecting the adaptation to environmental conditions. ©FUNPEC-RP.

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Blastocerus dichotomus, the marsh deer, is the largest Brazilian Cervidae species. The species is endangered because of hunting and loss of its natural habitat, i.e., flood plain areas, because of hydroelectric power station construction and agricultural land expansion. In the present study, we tested 38 microsatellite loci from four Cervidae species: Odocoileus virginianus (7), Rangifer tarandus (17), Capreolus capreolus (7), and Mazama bororo (7). Eleven loci showed clear amplification, opening a new perspective for the generation of fundamental population genetic data for devising conservation strategies for B. dichotomus. © FUNPEC-RP.

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The efficiency of systems composed of two species of floating aquatic macrophyte (Eichhornia crassipes and Pistia stratiotes) to treat effluents from shrimp culture was evaluated in this research. The effluent originated from a pond populated with Macrobrachium amazonicum. Treatment systems consisted of 12 experimental tanks with aquatic macrophyte and three tanks without plants (control). Water samples were collected from the fresh water supply and before and after passing through the treatment systems. There are no differences in the removal of nutrients between the two species. The higher nutrient removal was observed for total phosphorus (41.9% by control; 71.6% by E. crassipes; 69.9 by P. stratiotes; 72.5% by E. crassipes + P. stratiotes and 72.1 by P. stratiotes + E. crassipes) and turbidity (30.6% by control; 80.2% by E. crassipes; 75.2 by P. stratiotes; 79.8% by E. crassipes + P. stratiotes and 81.5 by P. stratiotes + E. crassipes). The systems containing aquatic macrophytes were efficient in nitrogen and phosphorus removal from M. amazonicum culture. © 2008 Sociedade Brasileira de Zootecnia.

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This study aimed to establish the adequate concentrations of nitrapyrin for the effective inhibition of oxygen demand required for the oxidation of nitrogen compounds during aerobic mineralization of leachate. The aquatic macrophyte Myriophyllum aquaticum was used as a source of dissolved organic matter (DOM). The leachate was incubated in several chambers, containing different composition and treatments: (i) treatment with leachate (DOM), (ii) treatment with DOM plus nitrapyrin in different concentrations (10; 25 and 50 mg L-1), aiming at finding the right concentration that inhibits the nitrification process, (iii) treatment with DOM plus NH4SO 2, (iv) treatment containing DOM and nitrapyrin plus NH 4SO2, and (v) treatment with DOM plus azide. The dissolved oxygen amount in each incubation treatment was periodically measured. The results indicated that the ratio of 10 mg L-1 of nitrapyrin for each 10 mg C of leachate is efficient in inhibiting the oxidation of nitrogen compounds from aquatic macrophytes.

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The purpose of this randomized study was to evaluate EMG spectral, subjective and cardiovascular recovery parameters after isometric lumbar extension contractions. Ten healthy women performed isometric lumbar extensions until exhaustion with 5%, 10%, 15% and 20% of maximal voluntary isometric contraction on 4 different days (random order). One baseline five second contraction was performed before the fatiguing task which was followed by eight submaximal five second extension contractions (until 20 minutes after the end of the fatiguing task) at the same intensity as the trial to evaluate muscle recovery. EMG (Median Frequency, Peak Power, Peak Power Frequency, Total Power and Zero-crossing Rate) and cardiovascular variables did not demonstrate any statistical difference between the 5-second contractions (p > 0.05) performed before and after the fatiguing task, showing a quick EMG recovery. However, the data analysis showed that the perceived effort variable had not recovered even 10 minutes after the fatigue contraction (p < 0.05). Our results represent a data basis for future comparisons and since subjective felling can affect performance, this study shows the importance of its analysis, since the subjective effort rate was not fully recovered after 10 minutes the end of the exhaustion contraction. © 2008 IOS Press. All rights reserved.

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In this work the multiarea optimal power flow (OPF) problem is decoupled into areas creating a set of regional OPF subproblems. The objective is to solve the optimal dispatch of active and reactive power for a determined area, without interfering in the neighboring areas. The regional OPF subproblems are modeled as a large-scale nonlinear constrained optimization problem, with both continuous and discrete variables. Constraints violated are handled as objective functions of the problem. In this way the original problem is converted to a multiobjective optimization problem, and a specifically-designed multiobjective evolutionary algorithm is proposed for solving the regional OPF subproblems. The proposed approach has been examined and tested on the RTS-96 and IEEE 354-bus test systems. Good quality suboptimal solutions were obtained, proving the effectiveness and robustness of the proposed approach. ©2009 IEEE.