Abstract: A method and device for monitoring large structures so as to detect defects, e.g. cracks. An electric current is supplied to a steel structure which is equipped with contact points between which are measured voltage drops caused by the impressed current. A relatively large number of fixed contact points are used all over the area which is to be monitored. The voltage drops are measured between selected pairs of contact points and these voltage drops are compared with corresponding voltage drops that have been measured previously in the same manner when the structure was in an initial condition, preferably without any defects. The monitoring can this be performed by means of robust and simple devices which are relatively impervious to rough environments.

Abstract: A method of isomerizing alkylbenzenes, in particular xylenes. The method is based on the application of a catalyst which comprises an inorganic oxide support containing at least one mixed oxide compound of SiO.sub.2 and Al.sub.2 O.sub.3 in any proportion, and performing the isomerization at a temperature between 150.degree. and 300.degree. C. under a pressure ranging from about atmospheric to a few atmospheres. The catalyst is produced by reaction of the support with an aluminum alkyl compound of the type AlR.sub.y X.sub.3-y, wherein R=CH.sub.3, C.sub.2 H.sub.5 or C.sub.3 H.sub.7, y=1 or 2 and X=Cl, preferably Al(C.sub.2 H.sub.5)Cl.sub.2. The support may be impregnated with platinum and/or rhenium. Characteristic features of this method are that the isomerization process can be run without any promotor, and that isomerization of xylene under moderate conditions yields a high degree of conversion and high selectivity.

Abstract: A wall structure for vessels, tanks, washing towers, tubes, boat hulls and the like can be manufactured from elements consisting of a core of rigid plastic foam which on a first side is coated with a layer of non-expanded plastic which adheres to the core and preferably is of the same type as the latter, whereas the core is exposed on the opposite side. The elements have an elongated plank-like shape with opposite side surfaces having respective groove-and tongue-like design for matching mutual engagement. They can be rigidly engaged in side-by-side relationship by welding and/or gluing. On an exposed face of the assembled elements, a reinforced plastic mass which sets into a continuous layer is applied, if desired after grinding for evening out irregularities.

Abstract: A new halographic method for converting one wave into another wave by means of a hologram is disclosed. This method comprises mixing an object wave with a reference wave whose wave front in the hologram plane is different from that of the actual reconstruction wave in the same plane. The phases and possibly also the amplitudes of these two wave fronts are combined in such a way that compensation is obtained for imaging errors caused by mutual inconsistencies between the wavelength ratio, the hologram scaling and the object scaling, and a displacement of the reconstructed object relative to the hologram. The reference wave and the reconstruction wave are chosen so that the converted object wave field becomes "as equal as possible" to a wave field coming from another but geometrically similar object at a different wavelength. In an example concerning seismic holography a formular for choosing a proper synthetic reference wave is given.

Abstract: This invention concerns a method for the production of a hologram of at least one object wave and reconstruction of the same by means of a spherical reference/reconstruction wave, whose focal point is located at a short distance from the hologram. This distance is located during the construction and the reconstruction process, such that only one reconstructed image is generated in a given position whereas the other images are simultaneously defocused. The distance is determined on the basis of the signal to noise ratio desired at the object position and geometrical dimensions which per se are known to cause defocusing, such as hologram size, distance between the hologram and the object, and the area of hologram apertures. Thus, one of the images of different order of one object wavefront or only one of a number of wavefronts encoded on the same halogram can be reconstructed by simply adjusting the distance.

Abstract: A new method for holographic processing of waves by means of an optical system is disclosed. The method is based on the generation of an unrecorded hologram, herein denoted virtual hologram, which satisfies optical requirements. The virtual hologram corresponds to the modulation of a reference wave, herein denoted virtual reference wave, with the object wave for a particular object, herein denoted real object. The virtual hologram exists in space in the form of an image of a recorded hologram, herein denoted real hologram, which satisfies technological requirements and which corresponds to the modulation of the transformed virtual reference wave, herein denoted real reference wave, with the transformed object wave which corresponds to a transformed object, herein denoted virtual object. Upon transformation of the real hologram by means of the optical system and a reconstruction wave, the virtual hologram is generated in space and the real object is reconstructed therefrom.

Abstract: An arrangement for concentrating sea waves, includes a grid-like structure of stopping and/or delaying elements adapted to influence the amplitude and/or phase of the waves and located in such positions in the water that the elements in interaction with the incident sea waves form an interference pattern which gives a concentration of the wave energy in a limited area (concentration area). When the wave energy is to be utilized for power production, the grid-like element structure is designed to give a concentration of the wave energy in a concentration area located in the short-range field of the element structure. Preferably the elements in the structure are mainly situated in front of the concentration area with respect to the dominant wave incident directions. Moreover, the element structure may have an extension (aperture) which is substantially larger than the wave length of the dominant waves at the location.

Abstract: A controllable, motor-driven undercarriage which comprises a first frame having non-driven castors and a second frame carrying driving wheels. The second frame can be turned relative to the first frame for changing the direction of the driving wheels and can be locked in any position relative to the first frame. The second frame is a two-armed lever which is pivotable about a central axis and at either end carries a driving wheel which is provided with an independently controllable driving means. The independently controllable driving-wheels are used both for the driving and steering of the undercarriage and for swinging the lever between different locked positions.

Abstract: The invention relates to physiologically active compounds which are coupling products between an N-acyl aspartic acid and a biologically active amine such as dopamine or serotonin.

Abstract: Method of producing a synthetic hologram from a wavefront being defined by geometrical points in space and by the phase and amplitude of the points, by computer calculation of quantized hologram areas, wherein each point and its hologram areas are considered separately during the calculation, whereafter the hologram areas of the points are generated for producing the hologram. The hologram areas of each point are considered in relation to the defined phase and amplitude of the point, determining for the phase the position of the hologram areas of the point by adjusting the length of radius vector from the point to each associated hologram area by using the phase in this point and the phase of a reference wave on the hologram area, and determining for the amplitude a number of areas for the point such that this number is proportional to the amplitude in the point.

Abstract: An arrangement for concentrating sea waves, includes a grid-like structure of stopping and/or delaying elements adapted to influence the amplitude and/or phase of the waves and located in such positions in the water that the elements in interaction with the incident sea waves form an interference pattern which gives a concentration of the wave energy in a limited area (concentration area). When the wave energy is to be utilized for power production, the grid-like element structure is designed to give a concentration of the wave energy in a concentration area located in the short-range field of the element structure. Preferably the elements in the structure are mainly situated in front of the concentration area with respect to the dominant wave incident directions. Moreover, the element structure may have an extension (aperture) which is substantially larger than the wave length of the dominant waves at the location.