291 research outputs found

    Rechtgeleiding voor ruwheidsmeting

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    Forest Resources of the Mackenzie River Valley, N.W.T. by R.P. Hirvonen

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    Aanleg van een demi-installatie voor micro vonkverspaningsmachine

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    Creative thinking and design

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    A criatividade, uma qualidade que vem sendo revalorizada, principalmente no âmbito da formação de equipes de trabalho trabalho, mostra-se ainda como um ponto de tensão no campo do design. Ao mesmo tempo em que é entendida como elemento fundamental para os processos de design, a criatividade ainda é mistificada pela maior parte dos designers como algo indecifrável e inatingível. Assim, este artigo faz uma aproximação entre a concepção jungiana sobre criatividade, advinda da área da psicologia, e os processos de design. Somando-se a isso, são destacadas algumas ferramentas e técnicas sobre criatividade, as quais podem contribuir com a atividade do designer.Abstract: The creativity is a quality that has been revalued, especially in the training of work teams work, but still shows up as a point of tension in the design field. While it is understood as a fundamental element for the design process, creativity is still mystified by most designers as something indecipherable and unattainable. This article makes a connection between the Jungian concept of creativity and design process, highlighting some tools and techniques on creativity, which may contribute to the activity designer

    Echolocating bats emit a highly directional sonar sound beam in the field

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    Bats use echolocation or biosonar to navigate and find prey at night. They emit short ultrasonic calls and listen for reflected echoes. The beam width of the calls is central to the function of the sonar, but directionality of echolocation calls has never been measured from bats flying in the wild. We used a microphone array to record sounds and determine horizontal directionality for echolocation calls of the trawling Daubenton's bat, Myotis daubentonii, flying over a pond in its natural habitat. Myotis daubentonii emitted highly directional calls in the field. Directionality increased with frequency. At 40 kHz half-amplitude angle was 25°, decreasing to 14° at 75 kHz. In the laboratory, M. daubentonii emitted less intense and less directional calls. At 55 kHz half-amplitude angle was 40° in the laboratory versus 20° in the field. The relationship between frequency and directionality can be explained by the simple piston model. The model also suggests that the increase in the emitted intensity in the field is caused by the increased directionality, focusing sound energy in the forward direction. The bat may increase directionality by opening the mouth wider to emit a louder, narrower beam in the wild

    First Record Of Sylvilagus Brasiliensis (linnaeus, 1758) (lagomorpha: Leporidae) In Rio Grande Do Norte State, Northeast Brazil

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    We document the first record of Sylvilagus brasiliensis (Linnaeus, 1758) in Rio Grande do Norte state, Brazil. An adult individual was photographed in October 2015 in the municipality of João Câmara. This is the northernmost report of this species for the Caatinga biome. This article also represents important data for the Rio Grande do Norte, since the mammal diversity of this state is practically unknown. © 2016 Check List and Authors.12

    Interpreting granulite facies events through rare earth element partitioning arrays

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    The use of rare earth element (REE) partition coefficients is an increasingly common tool in metamorphic studies, linking the growth or modification of accessory mineral geochronometers to the bulk silicate mineral assemblage. The most commonly used mineral pair for the study of high-grade metamorphic rocks is zircon and garnet. The link from U–Pb ages provided by zircon to the P–T information recorded by garnet can be interpreted in relation to experimental data. The simplistic approach of taking the average REE abundances for zircon and garnet and comparing them directly to experimentally derived partition coefficients is imperfect, in that it cannot represent the complexity of a natural rock system. This study describes a method that uses all the zircon analyses from a sample, and compares them to different garnet compositions in the same rock. Using the most important REE values, it is possible to define zircon–garnet equilibrium using an array rather than an average. The array plot describes partitioning between zircon and garnet using DYb and DYb/DGd as the defining features of the relationship. This approach provides far more sensitivity to mineral reactions and diffusional processes, enabling a more detailed interpretation of metamorphic history of the sample

    Varying CFRP workpiece temperature during slotting : effects on surface metrics, cutting forces and chip geometry

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    Carbon fibre reinforced thermoset polymer (CFRP) components are typically edge trimmed using a milling process to achieve final part shape. During this process the material is subject to significant heating at the tool-workpiece interface. Damage due to heating is fibre orientation specific; for some orientations it can lead to matrix smearing, potentially hiding defects and for others it can increase pullout. Understanding these relationships is critical to attaining higher throughput by edge milling. For the first time this study focuses on active heating of the CFRP rather than passive measurement, through use of a thermocouple controlled system to heat a CFRP workpiece material from room temperature (RT) up to 110 °C prior to machining. Differences in cutting mechanisms for fibres oriented at 0, 45, 90 and -45° are observed with scanning electron microscopy (SEM), and quantified with using focus variation with an increase of 89.9% Sa reported between RT and 110°C CFRP panel pre-heating. Relationships to cutting forces through dynamometer readings and tool temperature through infra-red (IR) measurements are also made with a novel optical method to measure cut chips presented. Results show an increase in chip length and width for increasing cutting temperature from RT to 110°C (3.39 and 0.79 µm for length and width, respectively). This work improves current understandings of how the cutting mechanism changes with increased temperature and suggests how improved milling throughput can be achieved

    Growth, microstructure, and failure of crazes in glassy polymers

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    We report on an extensive study of craze formation in glassy polymers. Molecular dynamics simulations of a coarse-grained bead-spring model were employed to investigate the molecular level processes during craze nucleation, widening, and breakdown for a wide range of temperature, polymer chain length NN, entanglement length NeN_e and strength of adhesive interactions between polymer chains. Craze widening proceeds via a fibril-drawing process at constant drawing stress. The extension ratio is determined by the entanglement length, and the characteristic length of stretched chain segments in the polymer craze is Ne/3N_e/3. In the craze, tension is mostly carried by the covalent backbone bonds, and the force distribution develops an exponential tail at large tensile forces. The failure mode of crazes changes from disentanglement to scission for N/Ne10N/N_e\sim 10, and breakdown through scission is governed by large stress fluctuations. The simulations also reveal inconsistencies with previous theoretical models of craze widening that were based on continuum level hydrodynamics
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