A cooling system and method for using the cooling system are described. The cooling system includes a plurality of individual piezoelectric cooling elements spatially arranged in an array extending in at least two dimensions, a communications interface and driving circuitry. The communications interface is associated with the individual piezoelectric cooling elements such that selected individual piezoelectric cooling elements within the array can be activated based at least in part on heat energy generated in the vicinity of the selected individual piezoelectric cooling elements. The driving circuitry is associated with the individual piezoelectric cooling elements and is configured to drive the selected individual piezoelectric cooling elements.

A cooling system and method for using the cooling system are described. The cooling system includes a plurality of individual piezoelectric cooling elements spatially arranged in an array extending in at least two dimensions, a communications interface and driving circuitry. The communications interface is associated with the individual piezoelectric cooling elements such that selected individual piezoelectric cooling elements within the array can be activated based at least in part on heat energy generated in the vicinity of the selected individual piezoelectric cooling elements. The driving circuitry is associated with the individual piezoelectric cooling elements and is configured to drive the selected individual piezoelectric cooling elements.

A hydraulic fracturing system can include valve apparatuses that control the delivery of fluid to high-pressure pumps that supply the fluid to a wellhead. The valve apparatuses can receive electronic signals from a control system to regulate the flow rate of the fluid to the high-pressure pumps. In one or more examples, the flow rate of the fluid can be controlled such that proppant in the fluid remains in solution.

A thin gas transportation device is provided and includes a shell, a check valve and a gas pump. The shell includes a shell surface, an accommodation slot and an outlet slot. The accommodation slot is recessed from the shell surface and includes an accommodation bottom surface. The outlet slot is recessed from the accommodation bottom surface. The check valve is disposed within the accommodation slot and includes a barrier plate and a valve plate. The barrier plate is disposed on the accommodation bottom surface and covers the outlet slot. The barrier plate includes a first surface, a second surface, a protruding part and a plurality of perforations. The protruding part is protruding from the second surface and located at the outlet slot. The valve plate is coupled to the second surface, and the protruding part abuts against the valve part and seals the valve hole.

A multi-chamber wobble plate pump that includes a housing with an inlet port, an outlet port and a plurality of pump chambers. The pump further includes a plurality of inlet valves each located within one of the pump chambers to control fluid flow from the inlet port to the pump chambers. The pump also includes a plurality of outlet valves that control fluid flow from the pump chambers to the outlet port. A wobble plate is coupled to a diaphragm and a plurality of pistons. The diaphragm has at least one flex area with a leading edge and a trailing edge. The diaphragm has a plurality of diaphragm piston openings each with a diaphragm piston opening centerline. The wobble plate has a plurality of wobble plate piston openings, each wobble plate piston opening having a wobble plate piston open centerline that is offset from one of diaphragm piston opening centerlines.

A valve spring fixing device and a plunger pump are disclosed. The valve spring fixing device includes a spring fixing piece, which includes a first supporting surface and a second supporting surface located at two ends of the spring fixing piece, and an intermediate portion located between the first supporting surface and the second supporting surface; and a spring mounting portion connected with the intermediate portion and configured to mount a valve spring, the first supporting surface and the second supporting surface are configured to contact with a valve box to fix the valve spring fixing device.

A valve spring fixing device and a plunger pump are disclosed. The valve spring fixing device includes a spring fixing piece, which includes a first supporting surface and a second supporting surface located at two ends of the spring fixing piece, and an intermediate portion located between the first supporting surface and the second supporting surface; and a spring mounting portion connected with the intermediate portion and configured to mount a valve spring, the first supporting surface and the second supporting surface are configured to contact with a valve box to fix the valve spring fixing device.

A valve plate assembly (1) of a hydraulic axial piston machine is described, the valve plate assembly comprising a wear plate (2) made of a ceramic material surrounded by a compression ring (4). Such a valve plate assembly should be produced and maintained in a cost-effective manner. To this end, the wear plate (2) is connected to a support plate (3) by means of the compression ring (4).

A valve plate assembly (1) of a hydraulic axial piston machine is described, the valve plate assembly comprising a wear plate (2) made of a ceramic material surrounded by a compression ring (4). Such a valve plate assembly should be produced and maintained in a cost-effective manner. To this end, the wear plate (2) is connected to a support plate (3) by means of the compression ring (4).

A fluid adjusting device includes a reservoir, at least two connection channels, at least two supply channels and at least one one-way valve, the reservoir is provided with a fluid storage cavity and at least two fluid outlets in communication with the fluid storage cavity, and the fluid storage cavity is configured to store a cooling fluid; the at least two connection channels can be connected to at least two circulation circuits respectively; the at least two fluid outlets are in communication with the at least two connection channels by means of the at least two supply channels respectively; and the at least one one-way valve is arranged in at least one of the at least two supply channels, and is configured to enable a fluid to flow from the reservoir to the corresponding connection channel in unidirectional manner. The fluid adjusting device can accurately control temperatures.