Abstract: The invention relates to a fuel cell system with at least one fuel cell for electrochemical conversion of two reactants. The fuel cell has two electrode areas, having a first supply line for supplying a first reactant to a first electrode area, and an outlet line, for emission of residual gas from the first electrode area. The residual gas has an electrochemically unconsumed portion of the first reactant, a recirculation element, for feeding the residual gas from the outlet line into the first supply line, and an outlet valve in order to emit the residual gas into an area surrounding the fuel cell system. The invention provides for the fuel cell system to have a monitoring unit in order to control the outlet valve. In particular, the monitoring unit opens the outlet valve when the energy required to feed the residual gas by the recirculation element exceeds an energy potential of the first reactant which is present in the residual gas.

Abstract: The subject of the present invention relates to a method and a protector for reducing degradation of fuel cell systems at transitions in operation, in particular at electrodes or catalysts in a combustion chamber of a stack of a PEM fuel cell system in startup and shutoff events of the fuel cell system. A switchable material delivery device is provided for varying a delivery of material to the fuel cell system, so that a transition from a first state of the fuel cell system to a second state of the fuel cell system can be initiated, such that a potential difference between different electrodes can be effected. At least one reducing mechanism is provided for reducing the potential difference between the different electrodes during the transition, in which the reducing mechanism includes at least one compensating device for an unequal gas distribution by reducing the proportions causing degradation, to reduce degradation.

Abstract: The invention relates to a fuel cell system with at least one fuel cell for electrochemical conversion of two reactants. The fuel cell has two electrode areas, having a first supply line for supplying a first reactant to a first electrode area, and an outlet line, for emission of residual gas from the first electrode area. The residual gas has an electrochemically unconsumed portion of the first reactant, a recirculation element, for feeding the residual gas from the outlet line into the first supply line, and an outlet valve in order to emit the residual gas into an area surrounding the fuel cell system. The invention provides for the fuel cell system to have a monitoring unit in order to control the outlet valve. In particular, the monitoring unit opens the outlet valve when the energy required to feed the residual gas by the recirculation element exceeds an energy potential of the first reactant which is present in the residual gas.

Abstract: The invention relates to a closed-loop control system for a controlled system for specifying at least one controlling variable to the controlled system, having a primary controller, for generating the controlling variable within an interval between a maximum controlling variable barrier and a minimum controlling variable barrier. At least one measuring means for determining a controlled variable of the controlled system is provided. At least one measurement system for ascertaining at least one state variable of the controlled system, and at least one secondary controller, for varying the maximum controlling variable barrier and the minimum controlling variable barrier as a function of the state variable are provided.

Abstract: The present invention relates to a fuel cell system with a fluid supply element and/or fluid control element. The fuel cell system includes a fuel cell, an anode train, and a cathode train. The fluid supply element and fluid control elements are disposed within the anode train and/or the cathode train. A sensor for detecting pressure fluctuations and/or pressure peaks in a fluid supply train of the anode and/or the cathode is provided.

Abstract: A fuel cell system has at least one fuel cell unit for generating electrical energy, a unit for storing or dispensing electrical energy, an electrical consumer for consuming electrical energy, a diagnostic unit for ascertaining a functional capability of the at least one fuel cell unit during a diagnosis phase, and a control unit for determining an electrical power generated at least during the diagnosis phase by the at least one fuel cell unit.

Abstract: The subject of the present invention relates to a method and a protector for reducing degradation of fuel cell systems at transitions in operation, in particular at electrodes or catalysts in a combustion chamber of a stack of a PEM fuel cell system in startup and shutoff events of the fuel cell system. A switchable material delivery device is provided for varying a delivery of material to the fuel cell system, so that a transition from a first state of the fuel cell system to a second state of the fuel cell system can be initiated, such that a potential difference between different electrodes can be effected. At least one reducing mechanism is provided for reducing the potential difference between the different electrodes during the transition, in which the reducing mechanism includes at least one compensating device for an unequal gas distribution by reducing the proportions causing degradation, to reduce degradation.

Abstract: The present invention relates to a fuel cell (1) with an air-supplied cathode region (2) and a device (3) for determining the oxygen content in the supplied air. It is characterized by the fact that a fuel cell operating state control unit (3) is provided, which determines the operating state for the mobile operation of the fuel cell based on the oxygen content that was determined.

Abstract: A fuel cell system has at least one fuel cell unit for generating electrical energy, a unit for storing or dispensing electrical energy, an electrical consumer for consuming electrical energy, a diagnostic unit for ascertaining a functional capability of the at least one fuel cell unit during a diagnosis phase, and a control unit for determining an electrical power generated at least during the diagnosis phase by the at least one fuel cell unit.

Abstract: The invention relates to a method of manufacturing non-slip floor coverings made of mineral materials, such as, for example, natural stone, fine stoneware, artificial stone or ceramics. This method is carried out in a two-stage process, there being produced on the surface of the floor coverings or slabs, in a first process stage by means of pulsed laser bombardment, statistically distributed microcraters invisible to the human eye. The surface of the floor coverings or slabs obtained in this way is then, according to the invention, subjected to hydromechanical aftertreatment.

Abstract: The invention relates to a device and method for structuring the surface of floor coverings which have already been laid, comprising various floor coverings which may also consist of mineral materials such as natural or artificial stone. The object of the invention is to provide floor coverings which have already been laid with a structure on their surface, which structure makes it possible to at least increase the nonslip properties even in the presence of slippy media, e.g. water. To do this, the invention uses a device with which at least one laser beam can be moved with controlled intensity and in at least one dimension across the surface to be structured, the elements for guiding and shaping the laser beam(s) being accommodated in a mobile part of the device, so that this mobile part is guided intermittently or continuously across the floor surface which is to be structured and, in the process, the structuring can be formed by means of the laser beam.

Abstract: A non-slip floor covering which includes a plurality of depressions that are regularly or randomly distributed over a floor covering surface such that the depressions provide a suction effect.

Abstract: A fire resistant glass partition having at least one field formed of a multi-layer fireproof glass and equipped with fittings for fastening and/or closing elements. An end face of a pane is covered all around with an edge-gripping sealing profile of an elastic material which, at least in its region facing the end face of the pane, is provided with a material that foams under the influence of heat. The fitting components extending into the edge region are also covered by the sealing profile, with the total thickness in the enclosed region essentially corresponding to the total thickness of the pane. In this way it becomes possible for fire resistant glass partitions to also employ the panes as self-supporting structural components and to also make the joints fire resistant.

Abstract: A fibrillated strand is made by a method wherein first a mass of a powder of a high polymer is compressed into a substrate having a density smaller than that of the high polymer and having a multiplicity of gas-filled voids. Then an intense heat beam is played on the substrate to melt the high-polymer powder and simultaneously heat the gas of the voids to explosively enlarge same while the beam and substrate are relatively displaced so that the substrate is melted along a path. The substrate is cooled at least at the path after irradiation by the beam to form a porous strand extending along the path in the substrate. This strand is separated from the substrate and is then at least uniaxially stretched. The beam is a CO.sub.2 TEM.sub.oo -mode laser beam and the method further comprises the step of focussing the laser beam on the substrate. The fused strand of the substrate is cooled so rapidly that it is normally not melted all the way through from top to bottom and from side to side.