Systems and methods are provided for using an additively manufactured vehicle, such as an UUV, with additively manufactured modules. The vehicle may be configurable such that additively manufactured modules or components may be detachably connected to the vehicle by hand, without the use of tools. Such modules may include connectors adapted to securely attach additional modules that may be detached by hand, without the use of tools. The additively manufactured modules may include ball bearings for rotating modules such as propellers and thrusters, and clips or tabs for detachable connection. The modules may include optical components for communications between a swarm of unmanned vehicles. Such optical modules for underwater vehicles may utilize nephelometry and/or turbidimetry to improve communications parameters based on scattered light measurements.

A bearing rolling element with a lattice internal structure provides several advantages over a solid bearing. It is lighter than a solid bearing, reducing centrifugal forces. For ceramic bearings, less material is required, and sintering times are reduced because bonding material can flow easily to near the surface. Elements with an internal lattice also offer advantages over hollow rolling elements. The shell can be thinner without sacrificing load capacity. The thinner shell reduces the time required for bonding material to be removed during sintering. The blank can be formed using various additive manufacturing processes.

The disclosure relates to an X-ray tube, comprising a cathode and an anode, the cathode and anode being accommodated in a housing which provides a vacuum environment.

A rolling bearing makes use of a porous rolling element and a selected kind of lubricant to impregnate with; is usable in various conditions; does not discharge foreign objects; and features low dust generation and long life. The rolling bearing includes an outer ring 2; an inner ring 1; and a plurality of rolling elements 3 assembled between mutually opposed outer ring track surface 2a and inner ring track surface 1a. The plurality of rolling elements 3 is provided by a combination of a porous rolling element 3a impregnated with a lubricant and a non-porous rolling element 3b.

A rolling bearing makes use of a porous rolling element and a selected kind of lubricant to impregnate with; is usable in various conditions; does not discharge foreign objects; and features low dust generation and long life. The rolling bearing includes an outer ring 2; an inner ring 1; and a plurality of rolling elements 3 assembled between mutually opposed outer ring track surface 2a and inner ring track surface 1a. The plurality of rolling elements 3 is provided by a combination of a porous rolling element 3a impregnated with a lubricant and a non-porous rolling element 3b.

A silicon nitride sintered body includes a silicon nitride crystal grains and grain boundary phases. Further, when D stands for width of the silicon nitride sintered body before being subjected to surface processing, relations between an average grain diameter dA and an average aspect ratio rA of the silicon nitride crystal grain in a first region from an outermost surface to a depth of 0 to 0.01D and an average grain diameter dB and an average aspect ratio rB of the silicon nitride crystal grain in a second region inside the first region satisfy the inequalities:

0.8≤ dA/dB≤ 1.2; and

0.8≤ rA/rB≤ 1.2.

A force-transmitting assembly includes a metal shaft having at least two longitudinally-extending grooves defined in an outer surface, and a metal hub having at least two longitudinally-extending grooves defined in an inner surface that surrounds the outer surface of the shaft. A plurality of discrete parts is disposed in the at least two longitudinally-extending grooves of the shaft and the hub in an interference-fit manner so as to transmit a torque from the shaft to the hub. Each of the discrete parts is composed of at least 50 mass % of technical ceramic selected from Si.sub.3N.sub.4, SiAlON, Al.sub.2O.sub.3, ZrO.sub.2, or a mixture of two or more of Si.sub.3N.sub.4, SiAlON, Al.sub.2O.sub.3, and ZrO.sub.2.

A bearing, including: an inner ring defining a first groove; an outer ring including a radially inner surface, the radially inner surface facing an axis of rotation of the bearing, defining a second groove, and defining at least one third groove; a cage radially disposed between the inner ring and the outer ring; a plurality of balls retained by the cage, and disposed in the first groove, and in the second groove; an annular sleeve including a first portion disposed in the third groove; and a resilient element urging the outer ring and the annular sleeve away from each other parallel to the axis of rotation of the bearing.

A silicon nitride sintered body includes at least one black portion with a major axis of 10 μm or more in a field of view with a unit area of 5 mm×5 mm, when observing an arbitrary cross-section of the silicon nitride sintered body using a metallurgical microscope. A major axis of the black portion is Preferably 500 μm or less. The number of the black portion within the field of view with a unit area of 5 mm×5 mm is preferably 2 or more and 10 or less. A segregation portion of Fe is preferably included in the black portion.

A ball spline with detour tracks includes spline shaft, nut part movable along a longitudinal direction of the spline shaft, and balls between the nut part and the spline shaft, wherein the nut part includes nut adapted to insert the spline shaft thereinto and retainers on longitudinal sides of the nut, the spline shaft includes tracks extended along the longitudinal direction, the nut includes load track grooves formed in longitudinal direction on inner peripheral surface into which the spline shaft is inserted and non-load circulating portions formed in the longitudinal direction, each retainer includes circulating grooves on the inner peripheral surface to face the load track groove and non-load circulating portion, the balls run between the tracks and the load track grooves, and each track includes track groove formed in longitudinal direction of the spline shaft and detour tracks whose longitudinal sides are connected to the track groove.