4,779 research outputs found

    Eroding ribbon thermocouples: impulse response and transient heat flux analysis

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    We have investigated a particular type of fast-response surface thermocouple to determine if it is appropriate to use a one dimensional transient heat conduction model to derive the transient surface heat flux from the measurements of surface temperature. With these sensors, low thermal inertia thermocouple junctions are formed near the surface by abrasive wear. Using laser excitation, we obtained the impulse response of these commercially available devices. The response of particular sensors can vary if new junctions are created by abrasive wear. Furthermore, the response of these sensors was found to deviate substantially from the one dimensional model and varied from sensor to sensor. The impulse response was simulated with greater fidelity using a two dimensional finite element model, but three dimensional effects also appear to be significant. The impact of these variations on the derived heat flux is assessed for the case of measurements in an internal combustion engine. When the measured impulse response is used to derive the surface heat flux, the apparent reversal of heat flux during the expansion stroke does not occur

    The general biology of Verruca stroemia (O.F. Muller) with some additional observation on penis development and moulting frequency in Balanus balanoides.

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    First paragraph: This thesis is largely concerned with the biology of Verruca stroemia (O.F. Mulller), a common species of the sublittoral and near-littoral of the eastern Atlantic. A small animal even when fully grown, it is not very conspicuous, and there is very little information on its general biology. V. stroemia is the only easily accessible species of the genus, all others being found only in relatively deep water. Two features of its biology are of particular interest: first, although boreo-arctic in its distribution it is not, like some other species of similar geographical distribution, restricted to a single annual brood; secondly, the genus Verruca is a primitive one, in many respects more closely allied to the Lepadomorpha than to the Balanomorpha with which it is classified. Both these aspects of the species have been considered, the latter particularly with reference to feeding and cirral activity. The relation of the major nauplii release to the spring diatom outburst and the effects of desiccation have been investigated since these are important in the ecology of the species and there is much comparative data on both for other cirripedes

    A new theory of the spalling of fireclay products with relation to thermal expansion

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    There is one factor that is responsible for much of the failure of refractories in furnaces and other metallurgical processes and boilers, namely spalling. Many times this action has been the cause of roofs to cave in, side walls to slump, and bungs to fail. Consequently it is a factor that is of utmost importance. The erosion and slag effects are also of greatest importance to refractory stability. Spalling, as referred to refractories, is defined as the breaking or crushing of the unit due to thermal, mechanical, or structural stresses, presenting newly exposed surfaces of the residual mass. Taking the above definition for what it is worth and studying the various parts of it in detail, some light may be thrown on the subject of spalling, its cause and cure --Introduction, page 1-2
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