A two-way flow control device including: a housing defining a first opening interface and a second opening interface, a rotor having a plurality of blades, each blade controllable to be angled in a range of positive and negative blade angles to generate respective positive and negative flows between the first opening interface and the second opening interface, first stator vanes mounted to the housing between the blades and the first opening interface, each including a respective stator vane slope having a stator vane angle which are collectively positive or negative angled; second stator vanes mounted to the housing between the blades and the second opening interface, each including a respective stator vane slope having a stator vane angle which are collectively opposite angled to the stator vane angles of the first stator vanes, the second stator vanes mounted to be circumferentially offset with respect to the first stator vanes.

A motor assembly that includes a motor having a motor casing, a rotatable shaft extending from said motor casing to a shaft length and a hub coupled to said rotatable shaft, the hub having a circumferential skid surface disposed immediately proximal to the motor casing and having a channel configured to seat a propeller, when a propeller is present, wherein a bending moment applied to the shaft through the hub results in the circumferential skid surface contacting said motor casing.

The present disclosure discloses a hiding fan, the hiding fan includes a turntable, a plurality of fan blades, and a synchronization mechanism, the synchronization mechanism includes a rotation ring and a plurality of connection rods, the rotation ring is mounted on the turntable, the rotation ring can rotate relative to the turntable around a central axis of the turntable, each fan blade has an installation end and a free end, the installation end has an installation portion and a connection portion, the installation portion is mounted on the turntable through a first rotation connection portion, a first end of the connection rod is mounted on the turntable on the rotation ring through a second rotation connection portion, a second end of the connection rods is mounted on the connection portion, the fan blade can rotate around a central axis of the first rotation connection portion.

A motor assembly that includes a motor having a motor casing, a rotatable shaft extending from said motor casing to a shaft length and a hub coupled to said rotatable shaft, the hub having a circumferential skid surface disposed immediately proximal to the motor casing and having a channel configured to seat a propeller, when a propeller is present, wherein a bending moment applied to the shaft through the hub results in the circumferential skid surface contacting said motor casing.

A cooling fan includes a hub, a plurality of blades, and a plurality of flow disturbing elements. The blades are arranged on a peripheral surface of the hub; each of the blades has a leading edge and a trailing edge opposite to the leading edge, and each of the blades has at least one flow disturbing element arranged at the trailing edge. Each of the flow disturbing elements includes an engaging part and an extending part opposite to the engaging part; the engaging part of each of the flow disturbing elements is connected to the trailing edge of the corresponding blade, and the extending part of each of the flow disturbing elements extends outwardly toward a direction away from the trailing edge of the corresponding blade.

An impeller includes a hub, and a plurality of blades supported by the hub, the blades being arranged in at least two blade rows. The impeller has a deployed configuration in which the blades extend away from the hub, and a stored configuration in which at least one of the blades is radially compressed, for example by folding the blade towards the hub. The impeller may also have an operational configuration in which at least some of the blades are deformed from the deployed configuration upon rotation of the impeller when in the deployed configuration. The outer edge of one or more blades may have a winglet, and the base of the blades may have an associated indentation to facilitate folding of the blades.

A system and method for records management and classification of files in a content management system having a server system that stores the files. A system detects when at least one of the files is classified by a user of a client computing system as a classified file, and based on the detecting of the classification of the one or more files, each classified file is removed from the client computing system. The system further detects when at least one of the files is declared as a permanent record by the user of the client computing system, and based on the detecting of the declaration as a permanent record, prevents editing by the client computing system of each file declared as a permanent record.

Apparatus and methods are described including manufacturing an impeller by forming a structure having first and second bushings at proximal and distal ends that are connected to one another by at least one elongate element. The elongate element is made to radially expand and form a helical elongate element. An elastomeric material is coupled to the helical elongate element, such that the helical elongate element with the elastomeric material coupled thereto defines a blade of the impeller. The coupling is performed such that a layer of the material disposed around a radially outer edge of the helical elongate element forms the effective edge of the impeller blade. A step is performed to enhance bonding of the elastomeric material to the helical elongate element in a manner that does not cause a protrusion from the effective edge of the impeller blade. Other applications are also described.

Apparatus and methods are described including coupling a rigid tube to a drive cable that comprises a plurality of coiled wires, by placing ends of the drive cable and the rigid tube at a given location within a butt-welding overtube. The ends of the drive cable and the rigid tube are visible when they are disposed at the given location within the butt-welding overtube, via a window defined by the butt-welding overtube. The placement of the drive cable within the butt-welding overtube is such that a helical groove within a portion of the butt-welding overtube is disposed over the drive cable. Welding rings are formed around the butt-welding overtube. Other applications are also described.

A motor assembly that includes a motor having a motor casing, a rotatable shaft extending from said motor casing to a shaft length and a hub coupled to said rotatable shaft, the hub having a circumferential skid surface disposed immediately proximal to the motor casing and having a channel configured to seat a propeller, when a propeller is present, wherein a bending moment applied to the shaft through the hub results in the circumferential skid surface contacting said motor casing.