Abstract: A method of interrupting a call established via an analog link between two terminals via a switching center, whether the call is telephonic, telematic or a combination of the two, comprises the transmission of a user alerting signal and a terminal alerting signal from the switching center to one of the terminals. Between these signals the call between the terminals is re-established. To detect the terminal alerting signal the terminal searches during a predetermined period for a pattern transmitted by the switching center comprising in succession a first silence signal with a power less than a predetermined power during a first predetermined period of silence, the terminal alerting signal, and a second silence signal during a second predetermined period of silence.

Abstract: A videotex asynchroneous transmission system uses a parity bit for each character, with a continuous ARQ-type retransmission method. The data are transmitted in blocks (so-called "code words"). Each code word is comprised of a block of seventeen bytes "1"-"15" constituting the characters which are to be transmitted encoded by seven bits b1-b7. The 8th bit b8 of each byte is the parity bit. The 16th byte is the check byte of the code word, and the 17th byte being the enabling byte of the code word.

Abstract: The method consists in preparing from the crude petroleum being processed a representative cut constituting a vaporized fraction having a known yield, in plotting the TBP curve of the cut by chromatographic analysis and by integration of the quantitative signal produced as a result of the analysis. The information obtained from the analysis is processed in order to operate a control unit for generating signals which serve to adjust the rates of withdrawal of the cuts at different predetermined levels of the column.

Abstract: Adjustment and control of a product fraction stream and especially gas oil are effected by a control unit after processing information supplied by an analyzer which takes a direct measurement of the temperature of filtrability of the stream and by detectors which deliver signals representing the flow rate of the gas oil withdrawn, the rate of withdrawn of the next higher product stream, the flow rate of the crude petroleum being processed, the flow rate of the stripping vapor and of the next lower product stream, and the slope of the distillation curve of the crude petroleum in the gas oil zone.

Abstract: An improved process for purifying gas containing hydrogen sulphide and possibly other acid impurities, by means of amines, consisting of absorption of these impurities by contact between the gas for purification and an amine solution, particularly a mono- or di-ethanolamine solution, steam regeneration of the amine solution after it has fixed the acid compounds, and recycling of the regenerated solution to the absorption zone, characterized by the fact that the sulphur content of the regenerated amine solution is kept at an optimum level by varying the flow of regenerating steam.This improved process ensures better elimination of acid compounds, particularly hydrogen sulphide, by means of amines, and keeps the cost of purification as low as possible.

Abstract: A process for automated regulation of a unit producing sulphur by oxidation of hydrogen sulphide, in which the flow of gas carrying oxygen into the unit is regulated so as to keep an operating parameter, based on measurement of the sulphurous compound of the residual gases, level with a reference value.It is characterized by the fact that the control signal, used to regulate the flow of gas containing oxygen at the unit inlet, is a combination of a signal based on measurements taken at the inlet, and representing the theoretical flow of this gas needed to keep the operating parameter at its reference level and another signal representing the correction needed in this flow to adjust the instantaneous value of the parameter to the reference level.This process allow better control of the sulphur unit, with increased efficiency and reduced atmospheric pollution.

Abstract: A process for automated regulation of a unit producing sulphur by oxidation of hydrogen sulphide, in which the flow of gas carrying oxygen into the unit is regulated so as to keep an operating parameter, based on measurement of the sulphurous compound of the residual gases, level with a reference value.It is characterized by the fact that the control signal, used to regulate the flow of gas containing oxygen at the unit inlet, is a combination of a signal based on measurements taken at the inlet, and representing the theoretical flow of this gas needed to keep the operating parameter at its reference level and another signal representing the correction needed in this flow to adjust the instantaneous value of the parameter to the reference level.This process allow better control of the sulphur unit, with increased efficiency and reduced atmospheric pollution.