TL;DR: This investigation provides the first in vitro model of disc prolapse that reliably ruptures discs under physiologically reasonable stress and supports the hypothesis that intervertebral disc Prolapse is peripheral in origin.
Abstract: Lumbar intervertebral disc herniation is thought to be related to senescent changes in the nucleus pulposus except in rare instances of trauma. This investigation provides the first in vitro model of disc prolapse that reliably ruptures discs under physiologically reasonable stress. Fourteen vertebral motion segments with intact posterior elements were loaded repetitively at 1.5 Hz in a combination of flexion (7 degrees), rotation (less than 3 degrees), and compression (1,334 N) for an average of 6.9 hours (range, 3.0-13.0 hours) in a materials testing machine. Loading was terminated when reaction force leveled off for more than 1 hour. Ten discs failed through annular protrusions, and four failed by nuclear extrusion through annular tears, supporting the hypothesis that intervertebral disc prolapse is peripheral in origin. The annulus fibrosus is the site of primary pathologic change.
TL;DR: In this article, an apparatus and method for removing a frangible rupture disc or other frangible device from a wellbore casing is described. And methods of perforating a well casing using a pressure pulse or an acoustical wave are also disclosed.
Abstract: An apparatus and method for removing a frangible rupture disc or other frangible device from a wellbore casing. The casing has a special casing section defining a plurality of holes therethrough. Rupturable glass ceramic discs or inserts are disposed in the holes and retained therein. The glass ceramic discs or inserts are adapted to withstand fluid differential pressure normally present in the wellbore but are rupturable in response to impingement by a pressure wave thereon. The pressure wave is provided by a pressure wave generating device positionable in the casing string adjacent to the holes in the special casing section. The pressure generative device may generate a pressure pulse or an acoustical wave. Methods of perforating a well casing using a pressure pulse or an acoustical wave are also disclosed.
TL;DR: A multi-stage air bag inflator includes a housing with at least two separated chambers (30, 32), each containing gas generating material (40) and an ignition system (50, 58) for activating the material to generate gas for rapidly filling an associated air bag as mentioned in this paper.
Abstract: A multi-stage air bag inflator includes a housing (22) with at least two separated chambers (30, 32), each containing gas generating material (40) and an ignition system (50, 58) for activating the material to generate gas for rapidly filling an associated air bag. An internal wall means (40) is provided in the housing (22) to form the separated chambers (30, 32) and the wall means has a bursting disc (62) designed to rupture in response to a predetermined level of gas pressure in one of the chambers (30) providing fluid communication between the chambers (30, 32). The frangible section is supported by an annular backing disc (60) against rupture in response to gas pressure in the other gas chamber (32) so that different levels of air bag inflation with gas are possible in response to the severity of the impact.
TL;DR: In this paper, a method and apparatus is provided for created multiple fractures in a subterranean formation with a single, continuous treatment operation, where a plurality of burst disk assemblies are included, each having an independent burst pressure and corresponding to a specific interval to be treated, whereby the assemblies are arranged on a work or completion string such that the assembly with the lowest burst pressure is positioned at the toe or lowest position, and subsequent assemblies have increasing burst pressures toward the heel of the string.
Abstract: A method and apparatus is provided for created multiple fractures in a subterranean formation with a single, continuous treatment operation. A plurality of burst disk assemblies are included, each having an independent burst pressure and corresponding to a specific interval to be treated, whereby the assemblies are arranged on a work or completion string such that the assembly with the lowest burst pressure is positioned at the toe, or lowest position, and subsequent assemblies have increasing burst pressures toward the heel of the string. As fluid is pumped down the string, pressure builds up to exceed the burst pressure of the first disk, allowing treatment fluid to contact the formation. Once a first interval treated or fractured, it may be isolated thereby allowing pressure to again build up in the string and burst subseqent disks.
TL;DR: In this article, the authors investigated self-ignition and flame propagation during the sudden release of high-pressure hydrogen were investigated experimentally, and they showed that self-fire can occur when bursting pressure is sufficiently high in spite of the shortness of the tube.
Abstract: Hydrogen is expected to be used as a clean energy carrier. However, when high-pressure hydrogen is suddenly released into the air through tubes, self-ignition can occur by a diffusion ignition mechanism. In this paper, the phenomena of self-ignition and flame propagation during the sudden release of high-pressure hydrogen were investigated experimentally. Experimental results show that self-ignition can occur when bursting pressure is sufficiently high in spite of the shortness of the tube. For example, self-ignition was observed at a bursting pressure as high as 23.5 MPa with 50 mm long tube. When self-ignition successfully occurs, a hydrogen jet flame is produced by the ignition. The flame is then stabilized at the tube outlet. From photodiode signals and flame images, the propagation of a flame inside the tube is confirmed and the flame is detected near the rupture disk as the bursting pressure increases. When the tube length is not long enough to produce self-ignition, a hydrogen flame is observed in the only boundary layer at the end of tube and it quenches after the flame exits the tube. Consequently, the formation of a complete flame across the tube is important to initiate self-ignition, which sustains a diffusion flame after jetting out of the tube into the air. Also, in order to establish a complete flame across the tube, it is necessary to have sufficient length such that the mixing region is generated by multi-dimensional shock–shock interactions.