Abstract: Deleting directories in a virtual distributed file system (VDFS), and non-virtual file systems, involves changing the name of a selected directory to a unique object identifier (UID) and moving the selected directory, named according to the UID, to a deletion target directory. A recursive process, implemented using a background deletion thread, starts in the current directory and identifies objects in the current directory. For an object that is a file or an empty directory, the object is added to a deletion queue. For an object that is a directory that is not empty, the recursion drops down into that directory as the new current directory. When the recursion has exhausted the selected directory, or some maximum object count has been reached, the objects identified in the deletion queue are deleted. This approach can also be used for file operations other than deletion, such as compression, encryption, and hashing.

Abstract: A modular hydrokinetic turbine system for installation in a water stream. The system is assembled from a number of blade modules and a number of support modules, connected in the direction of the water stream. Each blade module has turbine blades, a rotor shaft portion, and two-piece rotor shaft coupling. The support modules rest on the stream bed and support the blade modules. The rotor shaft couplings allow the blade modules to be connected such that the rotor shaft portions provide a rotor shaft, but also allow the blade modules to be separable from the support modules. A generator located at one end of the system is driven by the rotor shaft.

Abstract: A Network Virtualization Device (NVD) executes a set of Virtual Network Interface Cards (VNICs). The set of VNICs includes a first VNIC that forwards packets for a set of one or more packet flows. The NVD stores a first VNIC-related information that includes information identifying a first set of one or more packet flows and associated state information The NVD in response to determining that the state information for the first VNIC is to be synchronized with another NVD, identifies a first backup NVD for the first VNIC, wherein the first backup NVD is a backup for the first VNIC, and communicates to the first backup NVD, a portion of the state information stored by the NVD for the first VNIC.

Abstract: A submersible well pump assembly includes a pump driven by a motor. The pump has a number of stages, each stage including a diffuser having an annular diffuser inlet with an annular outer wall. Diffuser passages lead downstream and inward from the diffuser inlet. An impeller has a circumferential outer edge adjacent the outer wall of the diffuser inlet. Notches are formed in the circumferential outer edge, defining a serrated configuration.

Abstract: A submersible well pump assembly includes a pump driven by a motor. The pump has a number of stages, each stage including a diffuser having an annular diffuser inlet with an annular outer wall. Diffuser passages lead downstream and inward from the diffuser inlet. An impeller has a circumferential outer edge adjacent the outer wall of the diffuser inlet. Notches are formed in the circumferential outer edge, defining a serrated configuration.