Abstract: During backup of a database's data stored in individual files, it is not permissible for the data in the individual files to be altered, for reasons of consistency. For this reason, the files are blocked to altering access operations after a particular time during a backup operation. According to the invention, the backup operation is carried out in two parts. First, the files are transferred without there being any alteration block. A recording file is used to note files which are altered during transferring. These files are transferred again in a second part. During the second part an alteration block is required. It can be assumed that the number of files needing to be transferred in the second part is much smaller than the number of files needing to be transferred in the first part. For this reason, a significantly shortened alteration block is achieved.

Abstract: During backup of a database's data stored in individual files, it is not permissible for the data in the individual files to be altered, for reasons of consistency. For this reason, the files are blocked to altering access operations after a particular time during a backup operation. According to the invention, the backup operation is carried out in two parts. First, the files are transferred without there being any alteration block. A recording file is used to note files which are altered during transferring. These files are transferred again in a second part. During the second part an alteration block is required. It can be assumed that the number of files needing to be transferred in the second part is much smaller than the number of files needing to be transferred in the first part. For this reason, a significantly shortened alteration block is achieved.

Abstract: The invention refers to a device for distributing suspensions, particularly pulp suspensions, in a tank 1, particularly a bleaching tower. It is characterized by a disc 6 being provided near the base 3 of the tank with at least one opening 7 so that the suspension is fed to the tank 1 and distributed in cycles over the tank cross-section near its base 3.

Abstract: A memory management system for computer systems using a static tree management structure (RIT) for the free memory. Such structure enables short access times to the free memory without negatively influencing the data protection and availability. Such structure is particularly useful in real-time systems.

Abstract: A navigation system for guiding unmanned vehicles with any desired wheel configuration without guide wire for free movement on paths and along curves along a virtual reference path having at least one straight and/or curved section. Discrete elements are floor-installed which are in operative connection with a vehicle internal path control device via the vehicle's internal sensory analysis system for correcting the course of the industrial truck. The discrete elements are arranged at spaced locations exclusively along the area of the reference path forming a linear formation chain as navigation reference points P. The distance between the reference points P are either regular or irregular and may be relatively great distances equal to a multiple of the wheel base of the vehicle. The on-board sensory analysis system exclusively determines the distances and measures the distance between the longitudinal axis of the industrial truck and the navigation reference point P.

Abstract: A navigation system for guiding unmanned vehicles with any desired wheel configuration without guide wire for free movement on paths and along curves along a virtual reference path having at least one straight and/or curved section. Discrete elements are floor-installed which are in operative conneciton with a vehicle internal path control device via the vehicle's internal sensory analysis system for correcting the course of the industrial truck. The discrete elements are arranged at spaced locations exclusively along the area of the reference path forming a linear formation chain as navigation reference points P. The distance between the reference points P are either regular or irregular and may be relatively great distances equal to a multiple of the wheel base of the vehicle. The on-board sensory analysis system exclusively determines the distances and measures the distance between the longitudinal axis of the industrial truck and the navigation reference point P.

Abstract: A proximity switch comprises two magnetic field sensors for detecting an roach of a machine having a magnet. The two sensors are arranged in such a way that one of the sensors is at a smaller distance from the machine than the other sensor when the machine is in a detectable distance so that each of the two sensors responds to the approach of the magnetic field of the machine and outputs a detected signal based on the electrical output characteristics of the sensor. The detected signals from both sensors are fed to a differential circuit for generating a differential signal. In order to compensate interference field, the differential signal due to the magnetic field of the machine is set greater than the differential signal generated from the interference field. A circuit for converting the differential signal into an output signal is provided for the proximity switch.