796 resultados para Hot rolling
Resumo:
Pedagogues in the borderland of their social task: dealing with family law proceedings, threats and violence Drawing upon an explorative study of family law proceedings from a school perspective, the aim of this paper is to examine the school staff’s strategies for solving or coping with problematic situations in this context. Gendered conflicts between adults and violence are extreme cases for pedagogues in school and preschool. How do the staff cope with their own and the children’s vulnerability? Based upon interviews with 22 informants, the staff’s strategies are outlined and discussed in relation to organizational and professional circumstances and intersecting social relations of power. An analytical construction of six types of proactive and reactive strategies, ranging from distance keeping to normalization of own exposure, is utilized in the analysis. Findings suggest that the staff’s strategies to handle challenging events in this context vary with the parent’s gender, class position and ethnicity. Further, it is argued that creating a sense of safety and promoting learning among the children may be obstructed by lack of support from the school’s organization, demands on staff to perform customer oriented attitudes towards parents and lack of clarity concerning the limits of the social task. Conflicts between the organization and profession on the one hand and the educational and the social task on the other hand, are thus illuminated. In conclusion, a further aim of this article is to contribute to broader discussions on men’s violence against women and children – in families as well as in workplaces and in the intersection between these two areas.
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Increase in work related violence. A reflection of changes in working conditions? An analysis based on the Swedish Work Environment surveys. Victim surveys from Sweden show that the proportion reporting exposure to work related violence has increased. On the basis of the Swedish Work Environment surveys 1991–2005 this article focuses on the following questions: What kind of situations and working conditions are related to workplace violence? And, has the number of employees exposed to these working conditions increased parallel to the rise of reported workplace violence? Logistic regression analysis shows that some situations and working conditions are indeed related tothe risk of violence. To some extent exposure to these working conditions co-varies with exposure to violence. This result is more prominent for women than for men. Further research is needed to understand how changes in working conditions affect the risk of violence and the development thereof, not least from a gender perspective. Even so, changes in working conditions can not alone explain the increase of reported workplace violence in Sweden during this period. It seems that the influence of changed working conditions offers an interesting complement to criminological theories of broadened definitions and decreasing tolerance against violence in problematizing how an increase in reported workplace violence should and could be understood.
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o presente trabalho apresenta um resumo não só dos conceitos básicos sobre fundos de investimento, como também seu histórico e evolução no Brasil e no mundo, o contexto institucional nacional e os principais ratings de classificação de performance. Sua parte empírica foca-se no exame do fenômeno de persistência de performance para os fundos de investimentos ativos brasileiros entre julho de 1996 e junho de 2001. o estudo empírico dividiu-se em três partes: a comparação do retomo das categorias de fundos de ações ativos, de renda fixa e multimercados com os respectivos benchmarks e fundos passivos; a verificação do fenômeno de persistência baseando-se em Malkiel (1995); e a análise dos resultados de investimentos em portfólios formados pelos grupos de uma mesma categoria pertecentes a um mesmo percentil de retomo não ajustado ao risco.
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Foi avaliado o efeito do processo de defumação a quente (45-90ºC/5 horas) e a frio (27-45ºC/10 horas) nas propriedades organolépticas, no rendimento e na composição dos filés de matrinxã (Brycon cephalus). Não houve diferença significativa no rendimento de filés defumados e não-defumados. As perdas no processo de defumação foram significativamente maiores para defumação a quente (19,37%) em comparação à defumação a frio (17,08%). O processo de defumação reduziu a umidade (in natura = 72,91%; defumado a quente = 58,51%; e defumado a frio = 59,68%) e aumentou os teores de proteína bruta, lipídios e cinzas. Houve diferença significativa somente nos teores de proteína no defumado a quente (28,07%) e defumado a frio (27,14%). O processo a frio resultou em melhor aparência e cor de filé, enquanto o processo a quente melhorou o sabor, o teor de sal e a aparência geral. O aroma e a textura não diferiram significativamente entre os processos. O processo de defumação a quente melhora as propriedades organolépticas e os níveis de proteína do filé de matrinxã.
Resumo:
Wood gasification technologies to convert the biomass into fuel gas stand out. on the other hand, producing electrical energy from stationary engine is widely spread, and its application in rural communities where the electrical network doesn't exist is very required. The recovery of exhaust gases (engine) is a possibility that makes the system attractive when compared with the same components used to obtain individual heat such as electric power. This paper presents an energetic alternative to adapt a fixed bed gasifier with a compact cogeneration system in order to cover electrical and thermal demands in a rural area and showing an energy solution for small social communities using renewable fuels. Therefore, an energetic and economical analysis from a cogeneration system producing electric energy, hot and cold water, using wooden gas as fuel from a small-sized gasifier was calculated. The energy balance that includes the energy efficiency (electric generation as well as hot and cold water system; performance coefficient and the heat exchanger, among other items), was calculated. Considering the annual interest rates and the amortization periods, the costs of production of electrical energy, hot and cold water were calculated, taking into account the investment, the operation and the maintenance cost of the equipments. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.
Resumo:
Precipitation of FeTiP is reported to occur in Ti-added IF steels containing high P during thermomechanical processing. An ultra-low carbon (ULC) Nb-added steel ingot containing a higher P content (< 0.8 wt-%) was produced via aluminothermic reduction of Fe2O3 followed by double electron beam melting (EBM). FeNbP coarse precipitates were observed in the as-cast microstructure. After soaking at 1050
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This work discusses on the preparation of Ni-45Ti-5Mo, Ni-40Ti-10Mo and Ni-46Ti-2Mo-2Zr (at-%) alloys by high-energy ball milling and hot pressing, which are potentially attractive for dental and medical applications. The milling process was performed in stainless steel balls (19mm diameter) and vials (225 mL) using a rotary speed of 300rpm and a ball-to-powder weight ratio of 10:1. Hot pressing under vacuum was performed in a BN-coated graphite crucible at 900 degrees C for 1 h using a load of 20 MPa. The milled and hot-pressed materials were characterized by X-ray diffraction, electron scanning microscopy, and electron dispersive spectrometry. Peaks of B2-NiTi and Ni4Ti3 were identified in XRD patterns of Ni-45Ti-5Mo, Ni-40Ti-10Mo and Ni-46Ti-2Mo-2Zr powders milled for 1h. The NiTi compound dissolved small Mo amounts lower than 4 at%, which were measured by EDS analysis. Moreover, it was identified the existence of an unknown Mo-rich phase in microstructures of the hot-pressed Ni-Ti-Mo alloys.
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This paper presents a new methodology for the adjustment of the preheating process and steady-state operation of electronic ballasts intended for hot-cathode fluorescent lamps. The classical series-resonant parallel-loaded half-bridge inverter is the power stage analyzed in this paper. In addition, the preheating process is based on the imposition of a constant rms current through the electrodes, in order to provide a proper value of the R-h/R-c ratio before the lamp start. According to the proposed methodology, it is possible to set suitable operating points for, the electronic ballast, considering optimal conditions for the lamps electrodes. Therefore, the proposed methodology for setting the preheating and steady-state operation is a complete platform to the design of electronic ballasts for hot-cathode fluorescent lamps.
Resumo:
Microhardness measurements were carried out in a low carbon lamination steel after 6% of temper rolling, in order to evaluate local variations of work hardening as a function of crystallographic orientation. EBSD (electron back scattered diffraction) was used to determine grain orientations with respect to individual rolling planes and rolling directions. Hardness was shown to increase with the local Taylor factor. TEM observations and a well-known dislocation hardening model were used to confirm the equivalence between hardness values and the stored energy of cold work. A definite correlation between stored energy and Taylor factors could therefore be established, being more consistent than previous data reported in the literature. The improvement was thought to be related to the rather small plastic deformation, during which Taylor factors could be considered to remain constant. (c) 2006 Elsevier B.V. All rights reserved.
Resumo:
defect metal alloy strip when thixorolling directly from the semi-solid state. To facilitate the study lead/tin alloys were chosen for their relatively low operating temperature. The objective is to extrapolate these findings to the higher temperature aluminium, alloys. Three alloys (70%Pb30%Sn, 60%Pb-40%Sn, 50%Pb-50%wtSn) were used particularly to study the influence of the solidification interval. The equipment consists of a two roll mill arranged as an upper and lower roller, where both rollers are driven at a controlled speed. The lower roller is fed with semi solid alloy through a ceramic nozzle attached to the lower end of a cooling slope. Several types of nozzle and their position at the roller were tested. This produced different solidifications and consequently different finished strip. The alloys were first cast and then poured onto the cooling slope through a tundish in order to create a continuous laminar flow of slurry and uniformity of metal strip quality. The pouring was tested at different positions along the slope. The cooling slope was coated with colloidal graphite to promote a smooth slurry flow and avoid the problem of adherence and premature solidification. The metallic slurry not only cools along the slope but is also initially super-cooled to a mush by the lower roller whilst at room temperatures, thus enabling thixorolling. It was also found that the nozzle position could be adjusted to enable the upper roller to also contribute to the solidification of the metallic slurry. However the rollers and the cooling slope naturally heat up. Temperature distribution in these zones was analysed by means of three thermocouples positioned along the cooling slope and a fourth in the base of the semi solid pool within the nozzle. The objective being to design an optimum pouring and cooling system. The formed strip was cooled down to room temperature with a shower of water. Microstructures of the thixorolling process were analysed. The differences in solidification conditions resulted in differing qualities of finished strip and corresponding defect types, all of which are a serious quality issue for the rolled product.
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In this paper a non-isothermal two-phase model for oil-R134a refrigerant mixture flow is presented to predict the R134a leakage through the radial clearance of rolling piston compressors. The flow is divided in a liquid single-phase region and in a two-phase region, in which the homogeneous model is used to simulate the flow. The refrigerant leakage is determined using the mixture mass flow rate and the refrigerant mass fraction variation along the flow. The results are obtained for inlet pressures varying from 200 to 700 kPa, inlet temperatures ranging from 40 to 60 degrees C, and minimal clearances between 10 and 60 mu m. The results are firstly compared to existing isothermal model data, showing that there is a significant difference between the leakage flow rates predicted by isothermal and non-isothermal models. Finally, a useful general equation for compressor designers is proposed to calculate the refrigerant leakage for a large range of operation conditions. (C) 2012 Elsevier Ltd and IIR. All rights reserved.
Resumo:
We have used our new pulsed CO(2) laser, operating both on regular and hot bands, to excite the (13)CD(3)OH methanol isotopomer. This has lead to the observation of 13 new high-threshold far-infrared laser emissions (also identified as terahertz laser lines), with frequencies in the range between 24.11 and 102.56 cm(-1) (0.72-3.07 THz). The absorption transitions leading to these new FIR laser emissions have been located by observing the optoacoustic absorption spectra around the CO(2) emissions. Here, we present these new far-infrared laser lines, characterized in wavelength, polarization, offset relative to the center of the pumping CO(2) laser transition, relative intensity, and optimum operation pressure.