Abstract: A method of input signal resolution in a process control system where each of the actively redundant process control computers performs a common arbitration process on corresponding input signals. Blocks of corresponding input signals are mutually exchanged by the actively redundant process control computers, and an initial check is made to determine if these input signals are valid. For input signals representing valid analog values, a determination is made as to whether a predefined tolerance has been exceeded between corresponding input signals in the present process control cycle. When the predefined tolerance has been exceeded, then a check will be made to determine the predefined tolerance was also exceeded in the last process control cycle. If the predefined tolerance was not exceeded in the last process control cycle, then the analog input value selected during the last process control cycle will be employed in the present process control cycle.

Abstract: A stealth interface for an intelligent front-end communication system couples a plurality of actively redundant process control computers to a computer network. The stealth interface in each of the actively redundant process control computers includes a multi-ported memory for storing dynamic data associated with the physical process and for transferring this data to a front end computer which is in communication with the computer network. The multi-ported memory also includes a mailbox section for storing messages sent between the front end computer and its actively redundant process control computer. The stealth interface also includes a guardian circuit which ultimately controls the ability of the front end computer to write information to specific memory locations in the multi-ported data memory.

Abstract: A secure front-end communication system which couples a plurality of actively redundant process control computers to a computer network. The system includes a front end computer which is capable of establishing time limited communication contracts with one or more computer entity on the computer network. Each time limited communication contract is based upon an acceptable response to the transmission of an unpredicable signal from the front end computer, such as an encrypted transformation of a psuedo-random number generated by the front end computer. A security table is used to identify the network entities that are permitted to send write command messages to the process control computers to which the front end computer is connected. The front end computer also includes at least one permissive table which is used to determined whether a write command message from the network entity should be transmitted to the process control computer for which the message was intended.

Abstract: An extended Harvard architecture memory system which features an address store for containing an ordered sequence of program memory addresses, and a value store for containing a series of related data value sets. Each of the addresses contained in the address store is associated with a distinct set of instructions, such as a subroutine, that is contained in the program memory. The address store may also contain the address of one or more instruction arguments that are, in turn, contained in the value store or in a separate data memory. Both the address store and the value store are preferably connected to the same data communication path which is used by the data memory of the computer. The value store also includes a logic interface for enabling a plurality of different address increments to be programmably selected.

Abstract: A process and a computer implemented system for monitoring vibration in the blades of the rotor and stator of an axial compressor through measurement of pressure fluctuations of the dynamic pressure field in the region of the compressor housing in at least one stage of the compressor by means of at least one pressure sensing device sensitive to differential pressure fluctations affecting the blades at the characteristic frequency of the stage. The process and computer implemented system also assist in the control of the compressor by forwarding a status respecting rotor and stator mechanical vibration to the control unit.

Abstract: An adaptive process control system which is responsive to both process measurement input signals and economic environment inputs is provided. The process control system features an interactive optimization modeling system for periodically determining one or more manipulated process variables (also known as setpoints). These manipulated process variables are used to position directly controllable process parameters and attributes of a manufacturing system, such as a valve controlling the temperature of a coolant or a valve controlling the flow rate in a steam line.

Abstract: A process and device for detecting fouling of an axial compressor by measuring of pressure fluctuations within at least one of the stages of said compressor in the region of the compressor housing by means of at least one pressure sensing device, deriving a frequency signal from the signals delivered from said pressure sensing device, checking whether each of said frequency signals comprises at least one characteristic peak in the region of a characteristic frequency assigned to one of said compressor stages, and deriving a fouling parameter from said frequency signal, which parameter depends on a peak parameter indicative of the form of said characteristic peak and indicating the status of fouling of the compressor.

Abstract: The invention is a system and method for recovering volatile organic gases emitted by solid pellets of a polyetheylene resin product. In the process for making the resin product, the pellets are sampled for product quality and blended to obtain a more uniform mixture, before being transferred to shipping or storage containers. During this process gas must be purged from the sampler and blender vessels to prevent it from building up to an explosive level. In the purging step, outside air is blown through the blender and sampler vessels to mix with the organic gases therein, and this mixture is passed to a furnace, to provide combustion air for the furnace.