75 resultados para Teachers evaluation performance
em Biblioteca Digital da Produção Intelectual da Universidade de São Paulo (BDPI/USP)
Resumo:
Abad, CCC, Prado, ML, Ugrinowitsch, C, Tricoli, V, and Barroso, R. Combination of general and specific warm-ups improves leg-press one repetition maximum compared with specific warm-up in trained individuals. J Strength Cond Res 25(8): 2242-2245, 2011-Accurate assessment of muscular strength is critical for exercise prescription and functional evaluation. The warm-up protocol may affect the precision of the 1 repetition maximum (1RM) test. Testing guidelines recommend performing both general and specific warm-ups before strength tests. The general warm-up intends to raise muscle temperature, whereas the specific warm-up aims to increase neuromuscular activation. Although there is scientific evidence for performing the specific warm-up, the effects of general warm-up on strength tests are still unclear. The purpose of this study was to investigate whether the combination of a general with a specific warm-up (G + SWU) protocol would improve leg press 1RM values compared with a specific warm-up (SWU) protocol. Thirteen participants were tested for leg-press 1RM under 2 warm-up conditions. In the first condition, participants performed the SWU only, which was composed of 1 set of 8 repetitions at approximately 50% of the estimated 1RM followed by another set of 3 repetitions at 70% of the estimated 1RM. In the second condition (G + SWU), participants performed the 1RM test after a 20-minute general warm-up on a stationary bicycle at 60% of HRmax and the same specific warm-up as in the SWU. Values of 1RM in SWU and in G + SWU were compared by a paired t-test, and significance level was set at p <= 0.05. Strength values were on average 8.4% (p = 0.002) higher in the G + SWU compared with the SWU. These results suggest that the G + SWU induced temperature-dependent neuromuscular adjustments that increased muscle force production capacity. Therefore, these results support the recommendations of the testing guidelines to perform a moderate intensity general warm-up in addition to the specific warm-up before maximum strength assessments.
Resumo:
Nickel-based super alloys are used in a variety of applications in which high-temperature strength and resistance to creep, corrosion, and oxidation are required, such as in aircraft gas turbines, combustion chambers, and automotive engine valves. The properties that make these materials suitable for these applications also make them difficult to grind. Grinding systems for such materials are often built around vitrified cBN (cubic boron nitride) wheels to realize maximum productivity and minimum cost per part. Conditions that yield the most economical combination of stock removal rate and wheel wear are key to the successful implementation of the grinding system. Identifying the transition point for excessive wheel wear is important. The aim of this study is to compare the performance of different cBN wheels when grinding difficult-to-grind (DTG) materials by determining the 'wheel wear characteristic curve', which correlates the G-ratio to the calculated tangential force per abrasive grain. With the proposed methodology, a threshold force per grit above which the wheel wear rate increases rapidly can be quickly identified. A comparison of performance for two abrasive product formulations in the grinding of three materials is presented. The obtained results can be applied for the development of grinding applications for DTG materials.
Resumo:
This study deals with two innovative brewing processes, high gravity batch and complete continuous beer fermentation systems. The results show a significant influence of the variables such as concentration and temperature on the yield factor of the substrate into ethanol and consequently on the productivity of the high gravity batch process. The technological feasibility of continuous production of beer based on yeast immobilization on cheap alternative carriers was also demonstrated. The influence of process parameters on fermentation performance and quality of the obtained beers was studied by sensorial analysis. No significant difference in the degree of acceptance between the obtained products and some traditional market brands was found. (c) 2008 Institute of Chemistry, Slovak Academy of Sciences.
Resumo:
This work presents a theoretical and experimental study of the biodiesel (ethyl ester from a waste vegetable oil) performance in a flame tube furnace. The heat transfer rate was analysed in several sections along the furnace and the performance of the biodiesel was compared to that of diesel oil. The flow of heat from the burn of each fuel in the direction of the walls of the combustion chamber was evaluated under the same fuel injection pressure. The peak of the heat transfer occurred around 0.45 m far from the fuel injection nozzle in a 0.305 m inner diameter combustion chamber. The diesel oil showed a higher heat transfer rate in most parts exposed to the flame. In the region where the body of the flame is not present, the heat transfer of biodiesel becomes higher. (C) 2008 Elsevier Ltd. All rights reserved.
Resumo:
This study evaluated two different support materials (ground tire and polyethylene terephthalate [PET]) for biohydrogen production in an anaerobic fluidized bed reactor (AFBR) treating synthetic wastewater containing glucose (4000 mg L(-1)). The AFBR, which contained either ground tire (R1) or PET (R2) as support materials, were inoculated with thermally pretreated anaerobic sludge and operated at a temperature of 30 degrees C. The AFBR were operated with a range of hydraulic retention times (HRT) between 1 and 8 h. The reactor R1 operating with a HRT of 2 h showed better performance than reactor R2, reaching a maximum hydrogen yield of 2.25 mol H(2) mol(-1) glucose with 1.3 mg of biomass (as the total volatile solids) attached to each gram of ground tire. Subsequent 16S rRNA gene sequencing and phylogenetic analysis of particle samples revealed that reactor R1 favored the presence of hydrogen-producing bacteria such as Clostridium, Bacillus, and Enterobacter. (C) 2010 Elsevier Ltd. All rights reserved.
Resumo:
Effluents from pulp mill are usually toxic and mutagenic. This characteristic is mainly a consequence of xenobiotic compounds that are formed during the process. Global parameters such as chemical oxidation demand, total organic carbon and others, do not permit identify whether the toxic potential was remedied by the treatments or not. The objective of this research was to evaluate the performance of an horizontal-flow anaerobic immobilized biomass reactor (HAIB) treating the bleaching effluent from a Kraft pulp mill using toxicological (Daphnia similis - Ceriodaphnia sdvestrii) mutagenicity and citotoxicological assays (Allium cepa L). The results showed high sensibility of the test-organisms and capability of the anaerobic reactor to remove compounds that are exerting toxic and mutagenic effects. The bioassays represented an attractive alternative to water quality analyzes and the performance evaluation of treatments.
Resumo:
The main objective of this work was to investigate three packing materials (polyurethane foam, sugar-cane bagasse, and coconut fibre) for biofiltration of a gaseous mixture containing hydrogen sulphide (H(2)S). Mixed cultures were obtained from two sources, aerated submerged biofilters and activated sludge, and were utilised as inoculums. Biofilters reached 100% removal efficiency after two clays of operation. The empty bed residence time was 495 for each of the biofilters. The reactors were operated simultaneously, and the inlet concentrations of H(2)S varied between 184 and 644 ppmv during the long-term continuous operation of the biofilters (100 clays). Average removal efficiencies remained above 99.3%, taking into consideration the entire period of operation. Average elimination capacities reached by the biofilters packed with polyurethane foam, coconut fibre, and sugarcane bagasse were in the range of 17.8-66.6; 18.9-68.8, and 18.7-72.9g m(-3) h(-1), respectively. Finally, we concluded that the packing materials tested in this work are appropriate for the long-term biofiltration of hydrogen sulphide. (C) 2010 Elsevier B.V. All rights reserved.
Resumo:
The effect of a lipase-rich fungal enzymatic preparation, produced by a Penicillium sp. during solid-state fermentation, was evaluated in an anaerobic digester treating dairy wastewater with 1200 mg of oil and grease/L The oil and grease hydrolysis step was carried out with 0.1% (w/v) of solid enzymatic preparation at 30 degrees C for 24 h, and resulted in a final free acid concentration eight times higher than the initial value. The digester operated in sequential batches of 48 h at 30 degrees C for 245 days, and had high chemical oxygen demand (COD) removal efficiencies (around 90%) when fed with pre-hydrolyzed wastewater. However, when the pre-hydrolysis step was removed, the anaerobic digester performed poorly (with an average COD removal of 32%), as the oil and grease accumulated in the biomass and effluent oil and grease concentration increased throughout the operational period. PCR-DGGE analysis of the Bacteria and Archaea domains revealed remarkable differences in the microbial profiles in trials conducted with and without the pre-hydrolysis step, indicating that differences observed in overall parameters were intrinsically related to the microbial diversity of the anaerobic sludge. (C) 2009 Elsevier Ltd. All rights reserved.
Resumo:
Porous ceramic samples were prepared from aqueous foam incorporated alumina suspension for application as hot aerosol filtering membrane. The procedure for establishment of membrane features required to maintain a desired flow condition was theoretically described and experimental work was designed to prepare ceramic membranes to meet the predicted criteria. Two best membranes, thus prepared, were selected for permeability tests up to 700 degrees C and their total and fractional collection efficiencies were experimentally evaluated. Reasonably good performance was achieved at room temperature, while at 700 degrees C, increased permeability was obtained with significant reduction in collection efficiency, which was explained by a combination of thermal expansion of the structure and changes in the gas properties. (C) 2008 Elsevier B.V. All rights reserved.
Resumo:
The performance assessment as to water consumption in WC cisterns has contributed to the development of flushing system technologies, which allow smaller flushing volumes. The purpose of this work is to assess the performance of the the low water consumption requirement of WC cisterns with dual flushing system (6/3L), when compared to 6L flushing volume WC cisterns in multifamily buildings. The research methodology consisted of a case study in a multifamily residential building with submetering system, by monitoring the total water consumption and the two flushing systems using water meters installed in WC cisterns. By means of a mathematical model, a comparison of the design flowrate in the main branch was carried out considering the two types of WC cisterns. The results indicated that the water consumption in the 6L WC cistern was 20% in relation to the total domestic consumption, whereas the water consumption observed in the dual-flush WC cistern (6/3L) was 16%. The dual flushing system (6/3L) presented about 18% consumption reduction impact as compared to the 6 L system. The design flowrate values in the main branch, obtained by the mathematical model, were 0.35 L/s for systems with 6 L WC cistern and 0.34 L/s with dual-flush WC cistern (6/3 L), that is, a reduction of similar to 3%. Practical application: The knowledge of the performance in field of dual-flush WC cistern contributes to industry to improve this system and to users to aid their choice of technologies aimed at water conservation, and so assisting to the development of sustainable buildings.
Resumo:
The therapeutic ultrasound (US) is one of the resources mostly used by physiotherapists; however the use of uncalibrated equipments results in inefficient or even harmful therapies to the patient. In this direction, the objective of this study was to evaluate the performance and the procedures of utilization and maintenance of US in use in clinics and Physical-therapy offices. A questionnaire with questions related to the procedures applied in service during the use of therapeutic ultrasound was applied to physiotherapists. The performance of 31 equipments of 6 different brands and 13 different models was evaluated according to the IEC 61689 norm. The parameters measured were: acoustic power; effective radiating area (AER); non-uniformity ratio of the beam (RBN); maximum effective intensity; acoustic frequency of operation, modulation factor and wave form on pulsate mode. As for the questionnaires, it was evident that the professionals are not concerned about the calibration of the equipment. The results demonstrated that only 32.3% of the equipments were in accordance with the norms for the variables power and effective radiation area. The frequency analysis indicated that 20% of the 3 MHz transducers and 12.5% of the 1 MHz contemplated the norms. In the pulsate mode, 12.7% presented relation rest/duration inside allowed limits. A great variation of the ultrasonic field was observed on the obtained images, which presented beams not centered, sometimes with bifurcation of its apex. The results allow concluding that, although used in therapeutic sessions with the population, none of the equipments presents all the analyzed variables inside technical norms. (C) 2010 Elsevier B. V. All rights reserved.
Resumo:
Cementitious stabilization of aggregates and soils is an effective technique to increase the stiffness of base and subbase layers. Furthermore, cementitious bases can improve the fatigue behavior of asphalt surface layers and subgrade rutting over the short and long term. However, it can lead to additional distresses such as shrinkage and fatigue in the stabilized layers. Extensive research has tested these materials experimentally and characterized them; however, very little of this research attempts to correlate the mechanical properties of the stabilized layers with their performance. The Mechanistic Empirical Pavement Design Guide (MEPDG) provides a promising theoretical framework for the modeling of pavements containing cementitiously stabilized materials (CSMs). However, significant improvements are needed to bring the modeling of semirigid pavements in MEPDG to the same level as that of flexible and rigid pavements. Furthermore, the MEPDG does not model CSMs in a manner similar to those for hot-mix asphalt or portland cement concrete materials. As a result, performance gains from stabilized layers are difficult to assess using the MEPDG. The current characterization of CSMs was evaluated and issues with CSM modeling and characterization in the MEPDG were discussed. Addressing these issues will help designers quantify the benefits of stabilization for pavement service life.
Resumo:
Limb praxis can be influenced by age, gender, and education. The present Study investigated the influence of these variables on gesture production by healthy elderly Subjects. We evaluated 96 individuals divided into two age groups (60-74 and 75-88 years). Each group contained 48 men and 48 women and was subdivided into four groups according to education: illiterates and 1-3, 4-7, and 8 or more years of education. Individuals were requested to carry Out tasks oil verbal command and imitation. There were no differences between the performance of men and women, while older individuals performed worse than their younger counterparts. Regarding educational level, three major groups emerged: illiterates, individuals with 1-7 years of education, and those with 8 or more years of education. In conclusion, age and education significantly influenced the performance of individuals in limb praxis tests. (JINS, 2009, 157 618-622.)
Resumo:
The objective of this work was to analyze mechanical, physical and thermal performance of roofing tiles produced with several formulations of cement-based matrices reinforced with sisal and eucalyptus fibers. The physical properties of the tiles were more influenced by the fiber content of the composite than by the type of reinforcement. The type of the fiber was the main variable for the achievement of the best results of mechanical properties. Exposure to tropical climate has caused a severe reduction in the mechanical properties of the composites. After approximately four months of age under external weathering the toughness of the vegetable fiber-cement fell to 53-68% of the initial toughness at 28 days of age. The thermal performance showed that roofing tiles reinforced with vegetable fiber are acceptable as substitutes of asbestos-cement sheets. (c) 2006 Elsevier Ltd. All rights reserved.
Resumo:
Predictive performance evaluation is a fundamental issue in design, development, and deployment of classification systems. As predictive performance evaluation is a multidimensional problem, single scalar summaries such as error rate, although quite convenient due to its simplicity, can seldom evaluate all the aspects that a complete and reliable evaluation must consider. Due to this, various graphical performance evaluation methods are increasingly drawing the attention of machine learning, data mining, and pattern recognition communities. The main advantage of these types of methods resides in their ability to depict the trade-offs between evaluation aspects in a multidimensional space rather than reducing these aspects to an arbitrarily chosen (and often biased) single scalar measure. Furthermore, to appropriately select a suitable graphical method for a given task, it is crucial to identify its strengths and weaknesses. This paper surveys various graphical methods often used for predictive performance evaluation. By presenting these methods in the same framework, we hope this paper may shed some light on deciding which methods are more suitable to use in different situations.