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Apparatus is described for obtaining the curves relating area with time in photographic between-lens shutters. A set of separated and illuminated apertures fitted with neutral glass filters passing certain standard fractions of the light is imaged by a lens on film wrapped round a revolving drum, the shutter acting as a diaphragm for the lens. The film is thus exposed in bands along its length. An exposure is made, with the shutter set fully open, for one revolution of the drum. The above apertures are then replaced by a second set without neutral filters, each of these apertures fitting exactly between the spaces previously occupied by two apertures of the previous set. An instantaneous exposure of the shutter is then made during another revolution of the drum, During the whole of this exposure a time scale is impressed on the film by subsidiary apparatus. After development the points at which adjacent bands have the same density are found. These give the times at which the area of opening of the shutter was equal to the standard fractions of its full aperture. Various features of the apparatus are discussed, and particulars are given of the method of calibrating the neutral filters and of tests carried out on shutters for which curves relating area with time could be calculated.

According to the design of underground garage roof structure for a practical project, this paper introduces basic structure and designing method of the honeycombed core hollow floor , compared with the multi-ribbed floor design . Then it calculates economic and technical indexes of two kinds of floor scheme. The results shows that the garage roof with honeycombed core hollow floor has better technical and economic advantages .What’s more, it behaves with large space as well as span more especially.

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The capsule of the buoy is usually woven with composite materials. The existence of material anisotropy makes it difficult to establish the degradation mechanism model of the capsule, which affects the defect detection and health management of the capsule. To this end, this paper proposes a data-driven airbag defect detection method based on stress wave measurement. Firstly, strain signals under acoustic excitation are collected by sticking strain gauges on the surface of the capsule. Then, VMD is used to decompose the signal and extract the energy characteristics of each modal signal component to construct the feature vector. Finally, the feature vector is input into the GenSVM model for defect type recognition. The example analysis shows the effectiveness and applicability of the proposed method.