34 resultados para Processing technique of resin transfer molding (RTM)

em CentAUR: Central Archive University of Reading - UK


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The simulation and development work that has been undertaken to produce a signal equaliser used to improve the data rates from oil well logging instruments is presented. The instruments are lowered into the drill bore hole suspended by a cable which has poor electrical characteristics. The equaliser described in the paper corrects for the distortions that occur from the cable (dispersion and attenuation) with the result that the instrument can send data at 100 K.bits/second down its own suspension cable of 12 Km in length. The use of simulation techniques and tools were invaluable in generating a model for the distortions and proved to be a useful tool when site testing was not available.

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This paper investigates and evaluates the process of knowledge transfer in construction projects. Due to the highly competitive nature of business environments, knowledge transfer between organisations has become increasingly popular in recent years. However, although organisations can realise remarkable benefits by transferring knowledge from one unit to another, successful knowledge transfer can be difficult to achieve. The discussions presented in the paper are mainly based on findings of two case studies. The two cases were selected from Private Finance Initiative (PFI) projects in the UK. According to the case study findings, different stages of a knowledge transfer process can be overlapped, omitted, repeated as well as intermitted and then restarted. One of the significant findings of the case studies was the role of the "knowledge mediator". In selected case studies, there were external consultants and expert staff in the form of knowledge mediators. The importance of their roles was frequently highlighted by the interview participants. They were not only facilitating the close liaison between the knowledge source and the receiver, but also their role was strongly associated with practices of translation and interpretation. This combined role of mediator/translator, therefore, appears to be particularly significant for inter-organisational knowledge transfer in PFI projects.

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The temperature-time profiles of 22 Australian industrial ultra-high-temperature (UHT) plants and 3 pilot plants, using both indirect and direct heating, were surveyed. From these data, the operating parameters of each plant, the chemical index C*, the bacteriological index B* and the predicted changes in the levels of beta-lactoglobulin, alpha-lactalbumin, lactulose, furosine and browning were determined using a simulation program based on published formulae and reaction kinetics data. There was a wide spread of heating conditions used, some of which resulted in a large margin of bacteriological safety and high chemical indices. However, no conditions were severe enough to cause browning during processing. The data showed a clear distinction between the indirect and direct heating plants. They also indicated that degree of denaturation of alpha-lactalbumin varied over a wide range and may be a useful discriminatory index of heat treatment. Application of the program to pilot plants illustrated its value in determining processing conditions in these plants to simulate the conditions in industrial UHT plants. (C) 2008 Elsevier Ltd. All rights reserved.

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The total phenols, apigenin 7-glucoside, turbidity and colour of extracts from dried chamomile flowers were studied with a view to develop chamomile extracts with potential anti-inflammatory properties for incorporation into beverages. The extraction of all constituents followed pseudo first-order kinetics. In general, the rate constant (k) increased as the temperature increased from 57 to 100 °C. The turbidity only increased significantly between 90 and 100 °C. Therefore, aqueous chamomile extracts had maximum total phenol concentration and minimum turbidity when extracted at 90 °C for 20 min. The effect of drying conditions on chamomile extracted using these conditions was determined. A significant reduction in phenol concentration, from 19.7 ± 0.5 mg/g GAE in fresh chamomile to 13 ± 1 mg/g GAE, was found only in the plant material oven-dried at 80 °C (p ⩽ 0.05). The biggest colour change was between fresh chamomile and that oven-dried at 80 °C, followed by samples air-dried. There was no significant difference in colour of material freeze-dried and oven-dried at 40 °C.

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One central question in the formal linguistic study of adult multilingual morphosyntax (i.e., L3/Ln acquisition) involves determining the role(s) the L1 and/or the L2 play(s) at the L3 initial state (e.g., Bardel & Falk, Second Language Research 23: 459–484, 2007; Falk & Bardel, Second Language Research: forthcoming; Flynn et al., The International Journal of Multilingualism 8: 3–16, 2004; Rothman, Second Language Research: forthcoming; Rothman & Cabrelli, On the initial state of L3 (Ln) acquisition: Selective or absolute transfer?: 2007; Rothman & Cabrelli Amaro, Second Language Research 26: 219–289, 2010). The present article adds to this general program, testing Rothman's (Second Language Research: forthcoming) model for L3 initial state transfer, which when relevant in light of specific language pairings, maintains that typological proximity between the languages is the most deterministic variable determining the selection of syntactic transfer. Herein, I present empirical evidence from the later part of the beginning stages of L3 Brazilian Portuguese (BP) by native speakers of English and Spanish, who have attained an advanced level of proficiency in either English or Spanish as an L2. Examining the related domains of syntactic word order and relative clause attachment preference in L3 BP, the data clearly indicate that Spanish is transferred for both experimental groups irrespective of whether it was the L1 or L2. These results are expected by Rothman's (Second Language Research: forthcoming) model, but not necessarily predicted by other current hypotheses of multilingual syntactic transfer; the implications of this are discussed.

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Despite the fact that physical health and cognitive abilities decline with aging, the ability to regulate emotion remains stable and in some aspects improves across the adult life span. Older adults also show a positivity effect in their attention and memory, with diminished processing of negative stimuli relative to positive stimuli compared with younger adults. The current paper reviews functional magnetic resonance imaging studies investigating age-related differences in emotional processing and discusses how this evidence relates to two opposing theoretical accounts of older adults’ positivity effect. The aging-brain model [Cacioppo et al. in: Social Neuroscience: Toward Understanding the Underpinnings of the Social Mind. New York, Oxford University Press, 2011] proposes that older adults’ positivity effect is a consequence of age-related decline in the amygdala, whereas the cognitive control hypothesis [Kryla-Lighthall and Mather in: Handbook of Theories of Aging, ed 2. New York, Springer, 2009; Mather and Carstensen: Trends Cogn Sci 2005;9:496–502; Mather and Knight: Psychol Aging 2005;20:554–570] argues that the positivity effect is a result of older adults’ greater focus on regulating emotion. Based on evidence for structural and functional preservation of the amygdala in older adults and findings that older adults show greater prefrontal cortex activity than younger adults while engaging in emotion-processing tasks, we argue that the cognitive control hypothesis is a more likely explanation for older adults’ positivity effect than the aging-brain model.

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It is shown from flux transfer event (FTE) occurrence statistics, observed as a function of MLT by the ISEE satellites, that recent 2-dimensional analytic theories of the effects of pulsed Petschek reconnection predict FTEs to contribute between 50 and 200 kV to the total reconnection voltage when the magnetosheath field points southward. The upper limit (200 kV) allows the possibility that FTEs provide all the antisunward transport of open field lines into the tail lobe. This range is compared with the voltages associated with series of FTEs signatures, as inferred from ground-based observations, which are in the range 10–60 kV. We conclude that the contribution could sometimes be made by a series of single, large events; however, the voltage is often likely to be contributed by several FTEs at different MLT.

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The generation of flow and current vortices in the dayside auroral ionosphere has been predicted for two processes ocurring at the dayside magnetopause. The first of these mechanisms is time-dependent magnetic reconnection, in “flux transfer events” (FTEs); the second is the action of solar wind dynamic pressure changes. The ionospheric flow signature of an FTE should be a twin vortex, with the mean flow velocity in the central region of the pattern equal to the velocity of the pattern as a whole. On the other hand, a pulse of enhanced or reduced dynamic pressure is also expected to produce a twin vortex, but with the central plasma flow being generally different in speed from, and almost orthogonal to, the motion of the whole pattern. In this paper, we make use of this distinction to discuss recent observations of vortical flow patterns in the dayside auroral ionosphere in terms of one or other of the proposed mechanisms. We conclude that some of the observations reported are consistent only with the predicted signature of FTEs. We then evaluate the dimensions of the open flux tubes required to explain some recent simultaneous radar and auroral observations and infer that they are typically 300 km in north–south extent but up to 2000 km in longitudinal extent (i.e., roughly 5 hours of MLT). Hence these observations suggest that recent theories of FTEs which invoke time-varying reconnection at an elongated neutral line may be correct. We also present some simultaneous observations of the interplanetary magnetic field (IMF) and solar wind dynamic pressure (observed using the IMP8 satellite) and the ionospheric flow (observed using the EISCAT radar) which are also only consistent with the FTE model. We estimate that for continuously southward IMF ( ≈ 5 nT) these FTEs contribute about 30 kV to the mean total transpolar voltage (∼30%).