Abstract: Example solutions for performing federated graph queries use schemas and include: generating a logical graph using a query input and generating a physical plan using a query planning schema for double-nested loops, the outer loop for each permutation of data stores in a set of data stores, and the inner loop for each data store—ceasing when the logical graph has been fully consumed. A query cost is determined for each of the permutations, and a physical plan is selected based on the query cost, for example minimizing the query cost, and the query is executed based on the selected physical plan. The cost may be determined based on a weighted combination of factors such as freshness of the data, latency, power consumption, environmental impact (e.g., carbon footprint), energy efficiency, and network burden.

Abstract: An electrohydraulic system includes an output shaft, a hydraulic piston, and a preload device. The output shaft rotationally drives the valve and extends along a first axis. The hydraulic piston extends along a second axis perpendicular to the first axis, is actuated by a pressure medium, and rotates the output shaft. The preload device stores energy via preloading of an elastic element, which extends along a third axis, by a hydraulic cylinder and to transmit the energy to the output shaft in the event of a fault. The hydraulic piston is guided into first and second cylinder housings, and at least one of the cylinder housings is connected to the hydraulic cylinder. A check valve is arranged between the cylinder housing and the hydraulic cylinder, and is configured to decouple the preload device from the hydraulic piston, the blocking direction going from the hydraulic cylinder to the cylinder housing.

Abstract: An electrohydraulic system includes an output shaft, a hydraulic piston, and a preload device. The output shaft rotationally drives the valve and extends along a first axis. The hydraulic piston extends along a second axis perpendicular to the first axis, is actuated by a pressure medium, and rotates the output shaft. The preload device stores energy via preloading of an elastic element, which extends along a third axis, by a hydraulic cylinder and to transmit the energy to the output shaft in the event of a fault. The hydraulic piston is guided into first and second cylinder housings, and at least one of the cylinder housings is connected to the hydraulic cylinder. A check valve is arranged between the cylinder housing and the hydraulic cylinder, and is configured to decouple the preload device from the hydraulic piston, the blocking direction going from the hydraulic cylinder to the cylinder housing.

Abstract: An air flow control valve, for example for control of air of a ventilating flow in a vertilation system comprises an axially extending valve casing having a venturi-shaped inner face, and an axially movable valve member movable within said valve casing to vary the air flow through the valve. In order that the control movement of the valve member may vary the volume of air flow through the valve according to the same predetermined function regardless of the pressure drop across the valve, or the system in which it is incorporated, the valve casing is shaped to compensate for the variation of the drag coefficient of the valve resulting from movement of the valve member. The invention also comprises a method for determining the required dimensions of a valve casing incorporating such correction.

Abstract: A connector for connecting lengths of metal tubing such as used for air-conditioning or central heating ducts, comprises a cylindrical end part for insertion into an open end of the tubing. In order to provide a seal between the connector and the tubing the connector has a recess containing a hollow, flexible sealing ring into which fluid can be injected to expand the ring. In order to ensure an adequate seal both before and after expansion of the sealing ring the latter has outwardly projecting sealing flanges which, before expansion of the sealing ring, make a seal due to their own inherent resilience and/or the resilience of the sealing ring, and, after expansion of the sealing ring, form a seal under compression. In one embodiment of the connector a sealing flange is adapted to fold over and lie between the respective faces of the connector and the tubing to prevent metal to metal contact between them.