Abstract: An approach to detection and repair of application level semantic errors in deployed software includes inferring aspects of correct operation of a program. For instance, a suite of examples of operations that are known or assumed to be correct are used to infer correct operation. Further operation of the program can be compared to results found during correct operation and the logic of the program can be augmented to ensure that aspects of further examples of operation of the program are sufficiently similar to the examples in the correct suite. In some examples, the similarity is based on identifying invariants that are satisfied at certain points in the program execution, and augmenting (e.g., “patching”) the logic includes adding tests to confirm that the invariants are satisfied in the new examples. In some examples, the logic invokes an automatic or semi-automatic error handling procedure if the test is not satisfied.

Abstract: A downhole actuator apparatus that selectively maintains a pressure differential between two pressure regions in a well. The apparatus includes a body defining first and second chambers. A piston is slidably disposed in the body and is selectively moveable between first and second positions. A barrier is disposed in the body to selectively separate the first and second chambers. A fluid is disposed in the first chamber between the barrier and the piston. A control system that is at least partially disposed within the body is operable to generate an output signal responsive to receipt of a predetermined input signal. The output signal is operable to create a failure of the barrier such that at least a portion of the fluid flows from the first chamber to the second chamber and the piston moves from the first position to the second position.

Abstract: An approach to detection and repair of application level semantic errors in deployed software includes inferring aspects of correct operation of a program. For instance, a suite of examples of operations that are known or assumed to be correct are used to infer correct operation. Further operation of the program can be compared to results found during correct operation and the logic of the program can be augmented to ensure that aspects of further examples of operation of the program are sufficiently similar to the examples in the correct suite. In some examples, the similarity is based on identifying invariants that are satisfied at certain points in the program execution, and augmenting (e.g., “patching”) the logic includes adding tests to confirm that the invariants are satisfied in the new examples. In some examples, the logic invokes an automatic or semi-automatic error handling procedure if the test is not satisfied.

Abstract: A downhole actuator apparatus that selectively maintains a pressure differential between two pressure regions in a well. The apparatus includes a body defining first and second chambers. A piston is slidably disposed in the body and is selectively moveable between first and second positions. A barrier is disposed in the body to selectively separate the first and second chambers. A fluid is disposed in the first chamber between the barrier and the piston. A control system that is at least partially disposed within the body is operable to generate an output signal responsive to receipt of a predetermined input signal. The output signal is operable to create a failure of the barrier such that at least a portion of the fluid flows from the first chamber to the second chamber and the piston moves from the first position to the second position.

Abstract: A process for preparing an alkoxylation catalyst wherein a catalyst precursor which is formed from an alkoxylated alcohol and an alkaline earth metal compound to form a dispersion of an alkaline earth metal species is reacted with at least one alkylene oxide to alkoxylate at least a portion of the alkoxylated alcohol and forms a block alkoxylated alcohol.

Abstract: A process for preparing an alkoxylation catalyst wherein a catalyst precursor which is formed from an alkoxylated alcohol and an alkaline earth metal compound to form a dispersion of an alkaline earth metal species is reacted with propylene oxide to propoxylate at least a portion of the ethoxylated alcohol.