Abstract: A multilayer acoustic treatment panel including a first cellular-structure core sandwiched between a perforated skin and an intermediate skin; and a second cellular-structure core sandwiched between the intermediate skin and a continuous skin. The perforated skin includes at least one pair of high-porosity zones presenting a perforation ratio greater than a perforation ratio of a remainder of the perforated skin and including an inlet zone and an outlet zone longitudinally spaced apart from each other, the high-porosity zones of a given pair communicating through the first cellular-structure core and the intermediate skin with the two ends of a soundwave flow channel arranged in the second cellular-structure core.

Abstract: A multilayer acoustic treatment panel including a first cellular-structure core sandwiched between a perforated skin and an intermediate skin; and a second cellular-structure core sandwiched between the intermediate skin and a continuous skin. The perforated skin includes at least one pair of high-porosity zones presenting a perforation ratio greater than a perforation ratio of a remainder of the perforated skin and including an inlet zone and an outlet zone longitudinally spaced apart from each other, the high-porosity zones of a given pair communicating through the first cellular-structure core and the intermediate skin with the two ends of a soundwave flow channel arranged in the second cellular-structure core.

Abstract: The invention relates to a sampling method and apparatus for a fluidized bed of particles in an enclosure, comprising a sampling riser pipe (4) that communicates with the enclosure (1) below the upper surface of the fluidized bed and forms an extension thereof and has a restriction (5) adapted to limit the sampling flow rate, and means (14, 15) provided for injecting a compressed gas at an adjustable flow rate into the pipe (4) between the enclosure (1) and the restriction (5) with a view to controlling, by appropriate regulation of the flow rate of the gas, the quantity of particles withdrawn.

Abstract: An apparatus for the catalytic cracking of hydrocarbon feedstocks with reaction temperature control is provided which includes an upward-flow or downward-flow cracking column, means for feeding said column under pressure with a hydrocarbon feedstock and with particles of a regenerated cracking catalyst, at least one means for injection of an auxiliary fluid downstream of the zone in said column where the hydrocarbon feedstock and the regenerated catalyst particles are contacted with each other, to reduce the temperature of the reaction zone situated directly downstream thereof, means for separating the products of the cracked feedstock and the spent catalyst particles, at least one stripping means, at least one unit for regeneration of the catalyst by combustion of the coke deposited thereon and means for recycling the regenerated catalyst to said feeding means.