Abstract: In making a pressure vessel, spaced electrically conducting plates are separated by a pattern of electrically conducting tensile members which are held in that pattern by separable electrically conducting casing halves made of material which will not spot weld to the plates, the plates are forcibly engaged against the opposite ends of the tensile members and opposite ends of the casing halves while welding current is passed through and between the plates, and then the casing halves are removed whereafter marginal edges of the plates are joined by welding.

Abstract: The invention relates to a device for converting wind energy into another form of energy comprising a plurality of propellers having equidirectional shafts, being arranged in a matrix and driving associated energy converters.The invention generally proposes to design a device of the kind set forth in a manner such that the occupation density is at least 0.4 propellers per square meter. By this step a device is obtained, whose propellers are so small that the profile can satisfy an ideal profile with great accuracy without excessive increase in production costs. Furthermore, the number of revolutions during normal operation may be very appreciably higher than that of a known device so that the device only produces hardly troublesome, rustling noise, the level of which depends on wind force and thrust loads do no longer occur.

Abstract: The invention relates to a solar energy system comprising a collector consisting of a sloping space exposed to solar light for a heat transporting medium performing a primary circulation, which is thermally coupled by the downward run with a working medium circuit.An object of the invention is to design a solar energy system in a manner such that in contrast to the conventional system no control or safety apparatus is required, since solely natural, physical mechanisms are used so that a self-controlling operation is obtained, as a result of which the risk of disturbances and standstill is considerably reduced and the intrinsic safety is enhanced.The above-mentioned purposes are, in general, achieved by means of a system set forth in the preamble, the primary circulation of which takes place in a vessel partly filled with fluid and partly with the vapor thereof and operating as a heat pipe.

Abstract: A reinforced asphalt layer, consisting of an asphalt-forming mixture of bitumen with mineral particles, in which is embedded a reinforcing network of elongated reinforcing elements which, where they intersect one another, have a connection to one another which at least to a certain degree fixes the cross-bond, in which the reinforcing elements at least locally have a cross-section of maximum linear dimension of the order of the particle size, and a shape such as to exhibit a change of direction longitudinally from location to location of their engagement of the surrounding material of the layer, the arrangement being such that in a finished, rolled asphalt layer the reinforcing elements have adjusted locally to the mineral particles by deformation, on the one hand, and the reinforcing network has largely retained its elasticity, on the other.