Abstract: Apparatus and methods are provided for a tentative-hold-based protocol for distributed transaction processing. According to one embodiment, a distributed transaction coordinator receives information regarding an atomic distributed transaction representing an aggregation of multiple discrete transactions for resource items that span two or more network resources. The distributed transaction coordinator places a tentative hold on each of the resource items by causing a tentative hold record to be created and associated with each of the discrete transactions. The tentative holds operate in a non-mutually exclusive manner, thereby allowing the same resource item to be tentatively held by more than one transaction.

Abstract: A hand-held blast cleaning machine having a motor which serves as a handle. The machine includes a blast assembly for propelling abrasive material against a surface and a hopper for supplying abrasive material to the blast assembly. The blast assembly has a blast corridor, a rebound corridor, a blast opening, a blast wheel and a motor. The motor drives the rotation of the blast wheel and serves as a handle. The hopper has a return corridor, a collection area, a feed area and a vacuum conduit. The vacuum conduit is connected to a vacuum source to collect dust and debris from the blast cleaning operation. In one embodiment, an side-blast hopper, a down-blast hopper, an up-blast hopper and a side-feed hopper are all interchangeably attachable to the same blast assembly. A shut-off handle is attached to the blast assembly to provide automatic shut-off abrasive material to the blast wheel and to function as a second handle. In another embodiment, the motor serves as the only handle.

Abstract: A blast cleaning machine which gravity feeds abrasive material when blasting at positions from angularly upward to angularly downward. The machine includes a housing, a blast assembly, a motor for rotatably driving the blast assembly and a hopper. The housing has a blast corridor, a return corridor and a blast opening communicating with the blast corridor and the return corridor. The blast assembly receives abrasive material from the hopper and propels the abrasive material through the blast corridor and blast opening against the surface to be blast cleaned. The hopper has straight walls which are substantially parallel with the blast opening for gravity feeding abrasive material straight into the blast assembly. The walls of the hopper provide effective gravity feeding of abrasive material to the blast assembly when the machine is blasting anywhere between a 45-degree angle upward and a 45-degree downward.

Abstract: An apparatus for treating horizontal surfaces with abrasive particles. The apparatus utilizes a housing with flat, straight walls in a rebound chamber and a return corridor. Removable wearplates are attached to the inside walls of the rebound chamber to prevent wear on the rebound chamber walls. Abrasive particles are gravity-fed from a hopper to a blast drum having blades for propelling the abrasive particles to the surface to be treated. The abrasive particles rebound from the surface into the rebound chamber. The flat walls of the rebound chamber are arranged to divert the abrasive particles into the lower end of the return corridor with minimal wall contact. At the lower end of the return corridor the air flow from a dust collector takes over to draw the abrasive particles into a collection chamber. The abrasive particles pass through perforations in the wall of the collection chamber and into the hopper for reuse.