Abstract: A collapsible bladder has flexible outer walls and at least one strut inside the enclosure. The strut is connected to the outer walls and controls the shape into which the enclosure may be collapsed.

Abstract: A stringer comprises a base portion and first and second webs extending outwardly from the base portion. The orientation of at least one of the first and second webs may transition from a first angle to a second angle within an angle transition zone.

Abstract: A composite stiffener is fabricated using preforms of laminated, unidirectional composite tape. The stiffener includes a void that is reinforced by a filler wrapped with a structural adhesive. The surfaces of the preforms surrounding the void include a layer of composite fabric which is bonded to the filler by the adhesive, thereby increasing the toughness of stiffeners around the void and improving pull-off strength of the stiffener.

Abstract: A flyback converter uses primary side sensing to sense the output voltage for regulation feedback. Such sensing requires a predetermined minimum duty cycle even with very light load currents. Therefore, such a minimum duty cycle may create an over-voltage condition. In the flyback phase, after a minimum duty cycle of the power switch at light load currents, a synchronous rectifier turns off approximately when the current through the secondary winding falls to zero to create a discontinuous mode. If it is detected that there is an over-voltage, the synchronous rectifier is turned on for a brief interval to draw a reverse current through the secondary winding. When the synchronous rectifier shuts off, a current flows through the primary winding via a drain-body diode while the power switch is off. Therefore, excess power is transferred from the secondary side to the power source to reduce the over-voltage so is not wasted.

Abstract: A composite stiffener is fabricated using preforms of laminated, unidirectional composite tape. The stiffener includes a void that is reinforced by a filler wrapped with a structural adhesive. The surfaces of the preforms surrounding the void include a layer of composite fabric which is bonded to the filler by the adhesive, thereby increasing the toughness of stiffeners around the void and improving pull-off strength of the stiffener.

Abstract: Methods of forming a collapsible mandrel are disclosed herein. An example method disclosed herein includes forming a layup on a substrate by providing a first layer of rubber, positioning a reinforcement strip on the first layer of rubber, providing first and second release films in spaced apart from each other adjacent the reinforcement strip to expose a portion of the reinforcement strip, providing a second layer of rubber overlying the exposed portion of the reinforcement strip, and laminating the first and second layers of rubber to the reinforcement strip. The release films to prevent the first and second layers of rubber from adhering to each other and the reinforcement strip such that non-adhered ends of the first and second layers of rubber and the reinforcement strip define flaps. The method includes placing the layup in a cavity of a mold forming part of a tool assembly, consolidating the layup when the layup is in the cavity of the mold, and curing the layup to form the collapsible mandrel.

Abstract: A flyback converter uses primary side sensing to sense the output voltage for regulation feedback. A comparator on the primary side detects whether the output voltage has exceeded a predetermined regulated voltage by a first threshold to detect an over-voltage condition, resulting from a current generated by the converter exceeding the load current. Triggering of the comparator causes the converter to enter a non-switching sleep mode, whereby the output voltage droops over a period of time. When the output voltage has drooped below the predetermined regulated voltage by a second threshold, a synchronous rectifier is controlled to turn on, then off, to generate a pulse in the primary winding. Upon detection of the pulse, the sleep mode is terminated, and normal operation resumes until a regulated voltage is achieved or until the first threshold is again exceeded by the output voltage.

Abstract: A flyback converter uses primary side sensing to sense the output voltage for regulation feedback. Such sensing requires a predetermined minimum duty cycle even with very light load currents. Therefore, such a minimum duty cycle may create an over-voltage condition. In the flyback phase, after a minimum duty cycle of the power switch at light load currents, a synchronous rectifier turns off approximately when the current through the secondary winding falls to zero to create a discontinuous mode. If it is detected that there is an over-voltage, the synchronous rectifier is turned on for a brief interval to draw a reverse current through the secondary winding. When the synchronous rectifier shuts off, a current flows through the primary winding via a drain-body diode while the power switch is off. Therefore, excess power is transferred from the secondary side to the power source to reduce the over-voltage so is not wasted.

Abstract: Methods of producing the N-alkyl(alkyl)acrylamides. In a general embodiment, the present disclosure provides a method of producing an N-alkyl (alkyl)acrylamide comprising providing an aqueous solution comprising an N-alkyl amine and adding to the aqueous solution a base and an (alkyl)acrylic anhydride to form a precipitated N-alkyl(alkyl)acrylamide.

Abstract: A collapsible mandrel comprises an inflatable bladder. The bladder includes a reinforcement sandwiched between inner and outer layers of a fluoroelastomeric rubber.

Abstract: A collapsible bladder has flexible outer walls and at least one strut inside the enclosure. The strut is connected to the outer walls and controls the shape into which the enclosure may be collapsed.

Abstract: The invention provides compositions of matter, methods of their synthesis, and methods of their use in polymerization reactions. The compositions include polyfunctional initiators used to make star polymers when polymerized with monomers. The polyfunctional initiators are synthesized out of a multifunctional core with at least two functional groups and two or more initiator units bonded to the functional groups. The initiator units have two electron-withdrawing groups bonded to a central carbon atom and an azo group between the central carbon atom and the functional group. The polyfunctional initiators are particularly effective because when they decompose to form the radical core of a star polymer, the electron-withdrawing groups prevent the corresponding radical from forming any linear polymer contamination and only desired star polymers result.

Abstract: The invention provides compositions of matter, methods of their synthesis, and methods of their use in polymerization reactions. The compositions include polyfunctional initiators used to make star polymers when polymerized with monomers. The polyfunctional initiators are synthesized out of a multifunctional core with at least two functional groups and two or more initiator units bonded to the functional groups. The initiator units have two electron-withdrawing groups bonded to a central carbon atom and an azo group between the central carbon atom and the functional group. The polyfunctional initiators are particularly effective because when they decompose to form the radical core of a star polymer, the electron-withdrawing groups prevent the corresponding radical from forming any linear polymer contamination and only desired star polymers result.

Abstract: A stringer comprises a base portion and first and second webs extending outwardly from the base portion. The orientation of at least one of the first and second webs may transition from a first angle to a second angle within an angle transition zone.

Abstract: A stringer comprises a base portion and first and second webs extending outwardly from the base portion. The orientation of at least one of the first and second webs may transition from a first angle to a second angle within an angle transition zone.

Abstract: A collapsible mandrel comprises an inflatable bladder. The bladder includes a reinforcement sandwiched between inner and outer layers of a fluoroelastomeric rubber.

Abstract: This invention is directed to a composition comprising expandable polymeric microparticles comprising hydrophobic polymers having a backbone with labile pendant groups, the microparticles having an unexpanded volume average particle size diameter of from about 0.05 to about 5,000 microns. Labile pendant groups on the backbone are subject to hydrolysis under a change in environmental conditions that results in expansion of the microparticle. The invention is further directed to the use of the composition for modifying the permeability of subterranean formations and increasing the mobilization and/or recovery rate of hydrocarbon fluids present in the formations.

Abstract: Fluorescent monomers are described and claimed which are synthesized by reacting a substituted or non-substituted naphthalic anhydride with an amine and with a moiety containing a polymerizable group. Such monomers are useful for the preparation of tagged treatment polymers. Such tagged treatment polymers are useful as scale inhibitors in industrial water systems.

Abstract: A stringer comprises a base portion and first and second webs extending outwardly from the base portion. The orientation of at least one of the first and second webs may transition from a first angle to a second angle within an angle transition zone.

Abstract: The invention provides compositions of matter, methods of their synthesis, and methods of their use in polymerization reactions. The compositions include polyfunctional initiators used to make star polymers when polymerized with monomers. The polyfunctional initiators are synthesized out of a multifunctional core with at least two functional groups and two or more initiator units bonded to the functional groups. The initiator units have two electron-withdrawing groups bonded to a central carbon atom and an azo group between the central carbon atom and the functional group. The polyfunctional initiators are particularly effective because when they decompose to form the radical core of a star polymer, the electron-withdrawing groups prevent the corresponding radical from forming any linear polymer contamination and only desired star polymers result.