Abstract: A ducted-rotor aircraft includes a fuselage, one or more ducts, and a spindle that rotatably couples the one or more ducts to the fuselage. Each duct includes a hub that is configured to support a rotor, a plurality of stators that are coupled to the hub, a duct ring that is coupled to the plurality of stators, and a fitting that is coupled to a first stator of the plurality of stators. The fitting has a tubular collar that defines a first aperture that extends through the fitting. The collar is configured to receive a portion of the spindle. The first stator includes a rib that is spaced inward from the fitting and that defines a second aperture that is aligned with the first aperture and that is configured to receive an end of the spindle.

Abstract: A method of logging a wellbore casing and an adjacent formation comprises moving a measurement tool inside a borehole of the casing, wherein the casing is filled with air. Concurrently with moving the measurement tool inside the borehole, the method comprises emitting radioactive energy at an initial energy level from a radiation source of the measurement tool, wherein the radioactive energy is directed toward a wall of the casing and along a travel path from the radiation source to one or more detectors of the measurement tool, measuring energy loss of the radioactive energy at the one or more detectors relative to the initial energy level, and detecting a cement property outside of the casing based on the measured energy loss.

Abstract: A bearing system includes an inboard bearing assembly and an outboard bearing assembly. The inboard bearing assembly includes an inboard fitting and an inboard race. The inboard fitting includes a plate with a convex mating surface and a first aperture formed through the plate for receiving a blade root of a rotor blade. The inboard race comprising a concave mating surface configured to receive the convex mating surface a second aperture formed the inboard race. The outboard bearing assembly includes an outboard bearing assembly comprising an outboard fitting having an aperture formed therethrough for receiving the blade root of the rotor blade.

Abstract: A replaceable web structure for an aircraft frame is described and includes a plurality of structural members fabricated from a first type of material, the replaceable web structure comprising a plurality of web members fabricated from thin sheets of a second type of material, wherein each of the web members is fastened to a web frame of one of the structural members to replace a web portion of the one of the structural members; wherein the second type of material is lighter weight than the first type of material; and wherein the second type of material is more heat-resistant than the first material.

Abstract: One embodiment is a rotor system comprising a duct ring; a hub disposed centrally to the duct ring; first and second stators each connected between the duct ring and the hub; first and second control vanes rotatably connected to the first and second stators, respectively; a structural hoop having a first end connected to the first control vane and a second end connected to the second control vane, the structural hoop for translating rotation of the first control vane about a vane axis to the second control vane; and a mechanism for restricting at least one of forward-aft movement and side-to-side movement of the structural hoop relative to the duct ring.

Abstract: A fluid degradation monitoring system may detect a replacement of a fluid of a machine. The fluid degradation monitoring system may determine, after detecting the replacement of the fluid, a first degradation estimate of the fluid using a first technique based on characteristics relating to an operation of the machine. The fluid degradation monitoring system may detect a transition in a value of a dielectric constant of the fluid from a first phase to a second phase. The fluid degradation monitoring system may determine, after detecting the transition in the value of the dielectric constant, a second degradation estimate of the fluid using a second technique based on characteristics relating to the fluid.

Abstract: In some examples, an aircraft comprises an airframe, a rotor system coupled to the airframe, and a vibration attenuation system. The rotor system is operable to exert a vibratory force on the airframe. The vibration attenuation system comprises two or more batteries and elastic devices. The two or more batteries are operable to supply power to the rotor system. The elastic devices coupled to the two or more batteries and the airframe. The elastic devices are configured to attenuate the vibratory force based on facilitating oscillation of the two or more batteries. In other examples, a method comprises coupling elastic devices to two or more batteries and an airframe of an aircraft. The elastic devices receiving a vibratory force via the airframe and attenuate the vibratory force based on facilitating oscillation of the two or more batteries.

Abstract: A ducted-rotor aircraft includes a fuselage, one or more ducts, and a spindle that rotatably couples the one or more ducts to the fuselage. Each duct includes a hub that is configured to support a rotor, a plurality of stators that are coupled to the hub, a duct ring that is coupled to the plurality of stators, and a fitting that is coupled to a first stator of the plurality of stators. The fitting has a tubular collar that defines a first aperture that extends through the fitting. The collar is configured to receive a portion of the spindle. The first stator includes a rib that is spaced inward from the fitting and that defines a second aperture that is aligned with the first aperture and that is configured to receive an end of the spindle.

Abstract: A ducted-rotor aircraft includes a fuselage, first and second ducts, and a spindle that is coupled to the fuselage. Each duct includes a rotor having a plurality of blades. The first and second ducts are coupled to opposed ends of the spindle. The spindle is rotatably coupled to the fuselage with first and second bearings. The first bearing is configured to react to radial loads and the second bearing is configured to react to both radial and axial loads. The spindle includes a shaft, first and second fittings secured to opposed ends of the shaft, and first and second attachment interfaces that are attachable to the first and second ducts. The attachment interfaces may be integral with the fittings. Alternatively, the fittings may be configured to be secured to the attachment interfaces with fasteners.

Abstract: A duct for a ducted-rotor aircraft includes a hub, a duct ring, and a plurality of stators that extend outward from the hub. The duct ring defines a trailing edge. The duct includes one or more fittings, such as a system of fittings. Each fitting has a body that defines a first attachment interface that is configured to couple to structure of the duct ring and a second attachment interface that is configured to couple to one of the plurality of stators. The first and second attachment interfaces are spaced from each other such that when the fittings are coupled to the duct ring and the plurality of stators, all or substantially all of each of the plurality of stators are located aft of the trailing edge of the duct ring.

Abstract: A tissue anchor includes a memory metal wire configured to transition between an at least partially straightened delivery configuration and an expanded deployed configuration forming an anchor and a suture-attachment feature configured to have a suture coupled thereto. In the expanded deployed configuration, one or more portions of the memory metal wire extend radially outward from a center of the tissue anchor.

Abstract: A hub assembly for a ducted-rotor aircraft includes a plurality of stator supports, a first integral fitting that attaches to first ends of the stator supports, and a second integral fitting that attaches to second ends of the stator supports. The first fitting includes a plurality of motor attachment portions configured to locate and support a motor of the ducted-rotor aircraft, a plurality of fairing mounts configured to support attachment of an aerodynamic fairing to the hub assembly, and a plurality of stator locators configured to locate respective ones of the plurality of stator supports for attachment to the hub assembly. The first fitting has a body portion with an annular wall that supports the motor attachment portions, the fairing mounts, and the stator locators. The first fitting may be fabricated as a monolith that includes the body portion, motor attachment portions, fairing mounts, and stator locators.

Abstract: A duct for a ducted-rotor aircraft may include internal structural components such as a spindle that is supported by a fuselage of the aircraft, first and second annular spars that are attached to an end of the spindle, a central hub that supports a motor of the aircraft, a plurality of stators that extend from the central hub to the second spar, and a plurality of ribs that are attached to the first spar and the second spar at respective opposed ends. The spindle may include an attachment interface to which the first and second spars are attached. The attachment interface may be disposed at the second end of the spindle. The attachment interface may define first and second arc-shaped planar surfaces to which the first and second spars, respectively, are attached.

Abstract: A duct for a ducted-rotor aircraft may include an internal structure and an aerodynamic exterior skin that is adhesively bonded to the internal structure. The skin may include a leading-edge portion disposed at an inlet of the duct and an inner portion disposed along an interior of the duct. The inner portion of the skin may be bonded to the internal structure with a first bondline of adhesive and the leading-edge portion of the skin may be bonded to the inner portion of the skin with a second bondline of adhesive. One or both of the first and second bondlines of adhesive may be of non-uniform thickness to take up tolerance stackups between the inner portion of the skin, the leading-edge portion of the skin, and the internal structure.

Abstract: A computer implemented preventative maintenance schedule can includes a plurality of predetermined maintenance intervals. A replaceable maintenance item may be initially assigned to an initially assigned maintenance interval. A performance data associated with the replaceable maintenance item may be measured and an estimated end of useful life may be determined based on the performance data. The estimated end of useful life is compared to the assigned maintenance interval and, if warranted, the assigned maintenance schedule is modified.

Abstract: The present invention relates to microbial compositions useful in treating and remediating wastewater, removing organic matter from the surfaces of post harvested fruits and vegetables, and decreasing post-harvest disease in fruit and vegetables.