885 resultados para Usability tests


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The resistive-type superconducting fault current limiters (RSFCL) prototypes using YBCO-coated conductors have shown current limitation for medium voltage class applications for acting time up to 80 ms. By connecting an air-core reactor in parallel with the RSFCL, thus making an hybrid current limiter, one can extend the acting time for up to 1 s. In this work, we report the performance of a hybrid current limiter subjected to an AC peak fault current of 2 kA during 1 s for which within the first 80 ms the SFCL limits the current concurrently with the air-core reactor, and for the remaining 920 ms, only the air-core reactor limits the current. In order to evaluate the actual conditions for subsequent reconnection of RSFCL to the power grid, the hybrid fault current limiter was tested varying the time interval for recovery from 900 ms and 1.2 s, followed again by the concurrent operation of the hybrid limiter during 1 s (SFCL during 80 ms). From this evaluation test, the recovery time can be measured and compared using the voltage peak generated in superconducting module from the first and second fault test. The recovery time was also determined through the pulsed current method (PCM) on short-length sample test. The results showed that the fault current was limited from 1.9 kA down to 514 A after 1 cycle of 60 Hz frequency, with recovery time lower than 1.2 s for two subsequent fault current tests.

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The aim of this study was to adapt the methodology of the accelerated aging and electrical conductivity tests for determination of physiological potential in crambe seeds. Six seed lots of crambe (cv. FMS Brilhante) were subjected to determination of moisture content, germination test, first count germination, emergence, and emergence speed index. For the accelerated aging test, the traditional methodology was used with water, and with a saturated potassium chloride and sodium chloride solution in three periods of exposure (24, 48, and 72 hours) at 41 degrees C; the electrical conductivity test was performed with four pre-soaking treatments (0, 2, 4, and 8 hours) and four soaking periods (4, 8, 16, and 24 hours) at 25 degrees C. The accelerated aging test with water for 72 hours and the electrical conductivity test with 2 hours of pre-soaking and assessment after 16 hours were effective for classification of the crambe seed lots in regard to physiological quality.

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Objectives. To compare three different designs for measuring the bond strength between Y-TZP ceramic and a composite material, before and after ceramic surface treatment, evaluating the influence of the size of the adhesive interface for each design.Methods. 'Macro'tensile, microtensile, 'macro'shear, microshear, 'macro'push-out, and micropush-out tests were carried out. Two Y-TZP surface treatments were evaluated: silanization (sil) and tribochemical silica coating (30 mu m silica-modified Al2O3 particles + silanization) (TBS). Failure mode analysis of tested samples was also performed. Results. Both the surface treatment and the size of the bonded interface significantly affected the results (p = 0.00). Regardless of the type of surface treatment, the microtensile and microshear tests had higher values than their equivalent "macro" tests. However, the push-out test showed the highest values for the "macro" test. The tensile tests showed the greatest variability in results. The tribochemical silica coating method significantly increased bond strength for all tests.Significance. Different test designs can change the outcome for Y-TZP/cement interfaces, in terms of mean values and reliability (variability). The 'micro'tests expressed higher bond strengths than their equivalent 'macro'tests, with the exception of the push-out test (macro > micro). (C) 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

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Many models for unsaturated soil have been developed in the last years, accompanying the development of experimental techniques to deal with such soils. The benchmark of the models for unsaturated soil can be assigned to the Barcelona Basic Model (BBM) now incorporated in some codes such as the CODE_BRIGHT. Most of those models were validated considering limited laboratory test results and not much validation is available considering real field problems. This paper presents modeling results of field plate load tests performed under known suction on a lateritic unsaturated soil. The required input data were taken from laboratory tests performed under suction control. The modeling nicely reproduces field tests allowing appreciating the influence of soil suction on the stress-settlement curve. In addition, wetting induced or collapse settlements were calculated from field tests and were nicely duplicated by the numerical analysis performed.

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The main objective of this work is to illustrate an application of angular active control in a sectioned airfoil using shape memory alloys. In the proposed model, one wants to establish the shape of the airfoil profile based on the determination of an angle between its two sections. This angle is obtained by the effect of the shape memory of the alloy by passing an electric current that modifies the temperature of the wire through the Joule effect, changing the shape of the alloy. This material is capable of converting thermal energy into mechanical energy and once permanently deformed, the material can return to its original shape by heating. Due to the presence of nonlinear effects, especially in the mathematical model of the alloy, this work proposes the application of a control system based on fuzzy logic. Through numerical tests, the performance of the fuzzy controller is compared with an on-off controller applied in a sectioned airfoil model.

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The insecticide imidacloprid and the herbicide sulfentrazone are two different classes of pesticides that are used for pest control in sugarcane agriculture. To evaluate the genotoxic potential of low concentrations of these two pesticides alone and in mixture, the comet assay and the micronucleus (MN) test employing fluorescence in situ hybridization (FISH) with a centromeric probe were applied in human hepatoma cell lines (HepG2), in a 24-h assay. Mutagenicity was assessed by Salmonella/microsome assay with TA98 and TA100 strains in the absence and presence of an exogenous metabolizing system (S9). The results showed significant inductions of MN in HepG2 cells by both pesticides, for all the tested concentrations. As evidenced in the comet assay, only the imidacloprid presented significant responses. When the two pesticides were associated, a significant induction of damage was observed in the HepG2 cells by the comet assay, but not by the MN test. Moreover, the MN induced by the mixtures of the pesticides appeared at lower levels than those induced by sulfentrazone and imidacloprid when tested alone. According to the FISH results, the damage induced by imidacloprid in the HepG2 cells resulted from a clastogenic action of this insecticide (76.6% of the MN did not present a centromeric signal). For the herbicide sulfentrazone and for the mixture of the pesticides, a similar frequency of MN with and without the presence of the centromeric signal (herbicide: 52.45% of the MN without centromeric signal and 47.54% of the MN with centromeric signal; mixture: 48.71% of the MN without centromeric signal and 51.42% of the MN with centromeric signal) was verified. Based on these results, it was concluded that each one of the pesticides evaluated interacts with the DNA of HepG2 cells and causes irreparable alterations in the cells. However, the combination of the pesticides showed an antagonistic effect on the cells and the damage induced was milder and not persistent in HepG2 cells. The results obtained by the Ames test did not point out significant results.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Anaerobic efforts are commonly required through repeated sprint during efforts in many sports, making the anaerobic pathway a target of training. Nevertheless, to identify improvements on such energetic way it is necessary to assess anaerobic capacity or power, which is usually complex. For this purpose, authors have postulated the use of short running performances to anaerobic ability assessment. Thus, the aim of this study was to find a relationship between running performances on anaerobic power, anaerobic capacity or repeated sprint ability. Methods Thirteen military performed maximal running of 50 (P50), 100 (P100) and 300 (P300) m on track, beyond of running-based anaerobic sprint test (RAST; RSA and anaerobic power test), maximal anaerobic running test (MART; RSA and anaerobic capacity test) and the W′ from critical power model (anaerobic capacity test). Results By RAST variables, peak and average power (absolute and relative) and maximum velocity were significantly correlated with P50 (r = −0.68, p = 0.03 and −0.76, p = 0.01; −0.83, p < 0.01 and −0.83, p < 0.01; and −0.78, p < 0.01), respectively. The maximum intensity of MART was negatively and significantly correlated with P100 (r = −0.59) and W′ was not statistically correlated with any of the performances. Conclusion MART and W′ were not correlated with short running performances, having a weak performance predicting probably due to its longer duration in relation to assessed performances. Observing RAST outcomes, we postulated that such a protocol can be used during daily training as short running performance predictor.

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This paper presents results of stress cracking tests performed in high density polyethylene (HDPE) geomembranes (GM). Stress cracking tests were performed in accordance to ASTM D5397: Notched Constant Tensile Load Test (NCTL) and Single Point-Notched Constant Tensile Load Test (SP-NCTL). Tests were conducted to the fresh sample at 50ºC (standard test) and at 70ºC (accelerated condition) in order to compare the SC values. Results from accelerated tests (NCTL) showed, for instance, a total economy of 390 hours (comparing load stages of 25% yield stress) to perform the tests.

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Objective The present study aimed to examine the reproducibility of heart rate (HR) and rating of perceived exertion (RPE) values obtained during different incremental treadmill tests. Equipment and methods Twenty male, recreational, endurance-trained runners (10-km running pace: 10–15 km·h−1) performed, in a counterbalanced order, three continuous incremental exercise tests with different speed increments (0.5 km·h−1, 1 km·h−1 and 2 km·h−1). Thereafter, each participant performed the three tests again, maintaining the same order as before. The reproducibility of the HR and RPE values were analyzed for all protocols during submaximal intensities (8, 10, 12, and 14 km·h−1). In addition, it was examined the reproducibility of maximal HR (HRmax) and peak RPE (RPEpeak). Results The variability of both the HR and RPE values showed a tendency to decrease over the stages during the incremental test and was not or slightly influenced by the incremental test design. The HR at 14 km·h−1 and HRmax presented the highest reproducibility (CV < 2%). In contrast, the submaximal RPE values showed higher variability indices (i.e., CV > 5.0%). In conclusion, the HR values were highly reproducible during the stages of the incremental test, in contrast to the RPE values that presented limited reproducibility.

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Background: The negative sensory properties of casein hydrolysates (HC) often limit their usage in products intended for human consumption, despite HC being nutritious and having many functional benefits. Recent, but taxonomically limited, evidence suggests that other animals also avoid consuming HC when alternatives exist. Methodology/Principal Findings: We evaluated ingestive responses of five herbivorous species (guinea pig, mountain beaver, gopher, vole, and rabbit) and five omnivorous species (rat, coyote, house mouse, white-footed mouse, and deer mouse; N = 16–18/species) using solid foods containing 20% HC in a series of two-choice preference tests that used a nonprotein, cellulose-based alternative. Individuals were also tested with collagen hydrolysate (gelatin; GE) to determine whether it would induce similar ingestive responses to those induced by HC. Despite HC and GE having very different nutritional and sensory qualities, both hydrolysates produced similar preference score patterns. We found that the herbivores generally avoided the hydrolysates while the omnivores consumed them at similar levels to the cellulose diet or, more rarely, preferred them (HC by the white-footed mouse; GE by the rat). Follow-up preference tests pairing HC and the nutritionally equivalent intact casein (C) were performed on the three mouse species and the guinea pigs. For the mice, mean HC preference scores were lower in the HC v C compared to the HC v Cel tests, indicating that HC’s sensory qualities negatively affected its consumption. However, responses were species-specific. For the guinea pigs, repeated exposure to HC or C (4.7-h sessions; N = 10) were found to increase subsequent HC preference scores in an HC v C preference test, which was interpreted in the light of conservative foraging strategies thought to typify herbivores. Conclusions/Significance: This is the first empirical study of dietary niche-related taxonomic differences in ingestive responses to protein hydrolysates using multiple species under comparable conditions. Our results provide a basis for future work in sensory, physiological, and behavioral mechanisms of hydrolysate avoidance and on the potential use of hydrolysates for pest management.

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This study tested a dynamic field theory (DFT) of spatial working memory and an associated spatial precision hypothesis (SPH). Between 3 and 6 years of age, there is a qualitative shift in how children use reference axes to remember locations: 3-year-olds’ spatial recall responses are biased toward reference axes after short memory delays, whereas 6-year-olds’ responses are biased away from reference axes. According to the DFT and the SPH, quantitative improvements over development in the precision of excitatory and inhibitory working memory processes lead to this qualitative shift. Simulations of the DFT in Experiment 1 predict that improvements in precision should cause the spatial range of targets attracted toward a reference axis to narrow gradually over development, with repulsion emerging and gradually increasing until responses to most targets show biases away from the axis. Results from Experiment 2 with 3- to 5-year-olds support these predictions. Simulations of the DFT in Experiment 3 quantitatively fit the empirical results and offer insights into the neural processes underlying this developmental change.

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The Red-billed Quelea (Quelga quelaa), because of its widespread destruction of grain crops throughout its range in Africa, is one of the most studied and written about granivorous bird species. Less publicized are more local bird pests in Africa which may be equally Important. The Village Weaver, (Ploceus cucullatus), for example, is a pest in many countries, while some other Ploecids with limited destructive habits create local problems. Significant crop losses also occur where there are large populations of Golden Sparrows (Passer luteus), House Sparrows (Passer domesticus), Red Bishops (Euplectes oryx), Doves (Streptopelia spp.), Glossy Starlings (Lamprotornis chalybaeus), Parakeets (Psittacula spp.), and some waterfowl (Mackworth-Praed and Grant, 1952; Pans Manual No. 3, 1974; Park, 1974). Crop losses from local bird pests were reported in early February 1975 to the Sudan Plant Protection Bird Control Unit of the Ministry of Agriculture. A mechanized farm scheme in Khartoum North had large concentrations of Red Bishops roosting in maize and feeding on an early-maturing wheat variety (Mexicana). Small flocks of Golden Sparrows and House Sparrows also were present. Bird damage was clearly visible, especially at the corners and along the edges of the ripening wheatfields. Ground spraying with Queletox (60% a.1. Fenthion) on roosts of the Golden and House Sparrows was conducted along hedge rows of acacia (Acacia mellifera) located at the north end of the farm. Although the spray killed large numbers of roosting birds, damage con- tinued as the wheat matured. Pilot field trials were thus organized to test the effectiveness of other crop protection techniques. Because birds fed throughout many blocks of wheat which matured at different periods, it was felt that several different experiments could be conducted without Interfering with each other. The control techniques Included an acoustical repellent, a chemical repellent, a chemical frightening agent, and a trap. The experiments, conducted from February 7 through February 23, 1975, were not designed as an integrated control operation.