Abstract: A process and a system are proposed for short-time arc-welding elements, such as for example metal studs, on to components, such as for example metal sheets, wherein an element in the context of a welding operation is initially raised in relation to the component, a welding arc is formed between the element and the component, and the element is lowered again, the lifting height of the element in relation to the component being detected at least within a time segment between raising and lowering of the element. The initiation of the lowering operation and/or the lowering operation itself is controlled as a factor of the detected lifting height such that a previously specified total welding time is achieved.

Abstract: A process and a system are proposed for short-time arc-welding elements, such as for example metal studs, on to components, such as for example metal sheets, wherein an element in the context of a welding operation is initially raised in relation to the component, a welding arc is formed between the element and the component, and the element is lowered again, the lifting height of the element in relation to the component being detected at least within a time segment between raising and lowering of the element. The initiation of the lowering operation and/or the lowering operation itself is controlled as a factor of the detected lifting height such that a previously specified total welding time is achieved.

Abstract: The invention relates to a method for short-cycle arc welding with drawn-arc ignition, wherein a stud is welded to a piece of sheet metal, with the following steps: provision of a stud having an end face with which the stud is welded to a welding surface of the sheet metal, wherein an integral distinct projection is formed in the end face, placement of the projection on the welding surface and switch-on of an electric pilot current, lifting of the stud from the welding surface, whereby an arc is drawn, establishment of a welding current flowing through the arc in such a manner that the end face and the welding face start to melt, lowering of the welding stud onto the welding surface, wherein the melts at the end face and welding surface mix, and switch-off of the welding current so that the entire melt solidifies to join the stud to the sheet metal in a material-to-material manner, wherein after lifting of the welding stud and before establishment of the welding current, an alternating cleaning current is ini

Abstract: A locking device for vehicles, especially for aeroplanes, comprising an actively driven drive element provided with an input shaft and an output shaft which is directly or indirectly connected to the input shaft. According to the invention, at least one permanent magnet is associated with the input shaft or the output shaft, the magnet interacting with at least one other external fixed element, especially a permanent magnet.

Abstract: In an artificial endosphincter (1) for the urethra, comprising a retaining part (2) and a valve (10) which can be manually actuated by pressure from the outside, the retaining part (2) is formed as self-expanding stent. This permits gentle, simple and safe positioning as well as reliable and simple handling of the artificial endosphincter (1).

Abstract: A compound is of formula (I), in which: A1 to A4, E1 and E2 each independently represent hydrogen or an optionally-substituted hydrocarbon group; B1 and B2 each independently represent a single bond, an oxygen atom or an optionally-substituted hydrocarbon group; MG1 and MG2 each independently represent an optionally-substituted ring system; CG is a divalent or polyvalent chiral group. The optically active compound may be used as a doping agent for liquid crystals for a wide range of applications including solid state cholesteric filters for projection displays, circular polarisers, optical filters, etc.

Abstract: A liquid crystal switchable color filter switches between three color bands and is preferably used for time-sequential devices, such as projection devices, direct view displays and video cameras. The color filter may employ circularly polarizing selective reflection bands of at least four cholesteric filters together with three liquid crystal switches and related retarder layers. In one embodiment, the handedness of the second cholesteric is equal to the handedness of the third cholesteric filter and opposite to the handedness of the first and fourth cholesteric filter and, for the blocking state of a color band, the optic axis of the corresponding liquid crystal switch is parallel or perpendicular to the polarization direction. This concept leads to improved, excellent color saturation and requires less stringent production tolerances than in the prior art. Moreover, it advantageously allows overlapping color transmission bands thus improving the light efficiency.

Abstract: A device and a method are proposed for arc welding of elements, in particular metal studs to coated parts, in particular metal sheets, in which in a first step an element is moved relative to the part to at least partially break up the coating of the part. This produces an electrical contact between part and element, the part and the element being welded to each other in a subsequent step. The element is set in oscillating motion, at least about its lengthwise axis, in order at least partially to break up the coating of the part.

Abstract: Compounds of formula I: wherein the variables are defined as explained in the disclosure. The invention also provides liquid crystalline mixtures and optical or electro-optical devices including compounds of formula (I).

Abstract: In an artificial endosphincter (1) for the urethra, comprising a retaining part (2) and a valve (10) which can be manually actuated by pressure from the outside, the retaining part (2) is formed as self-expanding stent. This permits gentle, simple and safe positioning as well as reliable and simple handling of the artificial endosphincter (1).

Abstract: A cylinder head gasket includes a metal base plate; a combustion chamber opening provided in the base plate; a metal overlay surrounding the opening; and a weld bonding the overlay to the base plate. The weld is composed of a plurality of weld dots lying in a single row and being equidistantly spaced from one another. Each weld dot has a first diameter on a surface of the base plate and a second diameter on a surface of the overlay. The first diameter is smaller than the second diameter, and a distance between center points of adjoining the weld dots is greater than the second diameter of either of the adjoining weld dots.

Abstract: In an inventive stent (10), helical filaments (12, 13) are disposed on a first tubular layer (11). The helical filaments (12, 13) are mutually phase-shifted such that they do not touch and lie in one plane. The helical filaments (12, 13) are completely coated by a second elastic tubular layer (14) which is connected to the first elastic tubular layer (11). Further helical filaments may be disposed on the second elastic tubular layer (14). The inventive stent can be lengthened for introduction into a hollow organ and is self-expanding.

Abstract: Compounds of formula (I) wherein A, C and D represent (1) or (2), B represents (3) or (4) wherein at least one of the substituents is other than hydrogen and also at least one of the phenylene rings may be replaced by a 1,4-phenylene ring in which one or two non-adjacent CH groups have been replaced by nitrogen; k, l, m are 0 or 1, wherein k+l+m must be equal to 1 or 2; Z1, Z2, Z3 each independently of the others represents a single bond, —CH2CH2—, —CH2O—, —OCH2—, —COO—, —OOC—, —CH═CH—COO—, —OOC—CH═CH—, —(CH2)4—, —O(CH2)3—, —(CH2)3O— or —C≡C—; R1, R2 represent crosslinkable groups, and S1, S2 represent spacer units.

Abstract: Optically active butane-1,2,3,4-tetraol derivatives of formula (I). The compounds may be used as doping agents for liquid crystals for a wide range of applications, such as solid state cholesteric filters for projection displays, circular polarizers, and optical filters.

Abstract: Chiral prolinol derivatives of formula (1). The compounds may be used as doping agents for liquid crystals for a wide range of applications, including solid state cholesteric filters for projection displays, circular polarizers and optical filters.

Abstract: A compound is of formula (I), in which: A1 to A4, E1 and E2 each independently represent hydrogen or an optionally-substituted hydrocarbon group; B1 and B2 each independently represent a single bond, an oxygen atom or an optionally-substituted hydrocarbon group; MG1 and MG2 each independently represent an optionally-substituted ring system; CG is a divalent or polyvalent chiral group. The optically active compound may be used as a doping agent for liquid crystals for a wide range of applications including solid state cholesteric filters for projection displays, circular polarisers, optical filters, etc.

Abstract: A cylinder head gasket includes a metal base plate; a combustion chamber opening provided in the base plate; a metal overlay surrounding the opening; and a weld bonding the overlay to the base plate. The weld is composed of a plurality of weld dots lying in a single row and being equidistantly spaced from one another. Each weld dot has a first diameter on a surface of the base plate and a second diameter on a surface of the overlay. The first diameter is smaller than the second diameter, and a distance between center points of adjoining the weld dots is greater than the second diameter of either of the adjoining weld dots.

Abstract: A process for producing, on a metallic substrate, a geometric metal structure having a precise contour, including the steps of: solder coating a solder paste onto the substrate by screen printing to create the geometric metal structure, the solder paste comprising an organic binder system, and 80 to 95 weight % of a mixture of a nickel-based solder and a pulverulent alloy of nickel with at least one member selected from the group consisting of chromium, molybdenum, tungsten, manganese and iron, provided as a higher-melting metallic filler, wherein a weight ratio of solder to filler is 2-6:1, an average grain size of the solder is between 10 and 50 &mgr;m, and a grain size ratio of solder to filler, relative to the average grain size is from 0.5-2.5:1; drying the structure; decomposing the organic binder system present in the solder paste, without leaving a reside, by a heat treatment; and raising the temperature until the resulting solder material liquifies.

Abstract: A flat metal sealing gasket is made as follows: on an unhardened spring steel plate having an aperture and a bead surrounding the aperture, a sinterable powder is deposited along the bead in a desired shape and thickness. Thereafter a sufficiently high temperature is applied to the deposited sinterable powder to effect sintering or melting of the powder to provide a pressure-resistant overlay on the plate and to simultaneously effect a hardening of the plate.

Abstract: An optical frequency conversion element has a wave-guiding layer which consists of a .chi..sup.(2) -active ferroelectric liquid crystal. The monomeric or polymeric liquid crystal material has a periodic structure which permits the so-called quasi phase matching of a guided laser beam. The period length of the structure is equal to twice the coherence length l.sub.c =.pi./.DELTA..beta. of the material, whereby .DELTA..beta.=.beta..sub.o (2.omega.)-2.beta..sub.o (.omega.), with .omega.=angular frequency of the fundamental wave, 0=zero-order mode and .beta.=propagation constant of the mode.