Abstract: A method of DC-DC power conversion includes converting a DC link voltage to a DC output voltage for a load that is lower than the DC link voltage using a buck converter. The method includes controlling the buck converter in a normal switching mode in response to the DC link voltage being below a predetermined high threshold. The method also includes controlling the buck converter in a soft start switching mode in response to the DC link voltage being at or above the predetermined high threshold.

Abstract: A method of manufacturing a heat exchanger core from glass ceramic matrix composite includes placing one or more reinforcing fibers around one or more mandrels into a mold cavity. A glass matrix material infiltrates the one or more reinforcing fibers to produce an infiltrated core and the one or more mandrels is removed to create one or more passages passing through the infiltrated core.

Abstract: A method of detecting electrical arc damage includes receiving input indicative of electrical power as a function of time in an electrical arc. The method includes using the input to model an amount of damage caused by the electrical arc, and comparing the amount of damage to a predetermined threshold. The method includes flagging a warning in response to the amount of damage exceeding a predetermined threshold. The method can include breaking a circuit to stop the electrical arc. Flagging the warning can include signaling to an operator to inspect a unit potentially damaged by the electrical arc. The method can include inspecting the unit potentially damaged by the electrical arc.

Abstract: A system includes a variable displacement pump (VDP) in fluid communication with an inlet line and with an outlet line. The VDP includes a variable displacement mechanism configured to vary pressure to the outlet line. A bypass valve (BPV) includes a BPV inlet in fluid communication with the outlet line, and a BPV outlet in fluid communication with a bypass line that feeds into the inlet line upstream of the VDP. An actuator is operatively connected to control the BPV to vary flow from the BPV inlet to the bypass line. A controller is operatively connected to the actuator to control recirculation flow passed through the BPV based on requested flow from a downstream system supplied by the outlet line and based on a predetermined low threshold of flow through the VDP.

Abstract: A system includes a first electrohydraulic servo valve (EHSV) configured to be in fluid communication with a pressure supply and with a pressure return. The first EHSV includes a first actuator extend line and a first actuator retract line. A second EHSV is configured to be in fluid communication with the pressure supply and with the pressure return. The second EHSV includes a second actuator extend line and a second actuator retract line. An actuator includes an extend chamber in fluid communication with both of the first and second extend actuator lines, and a retract chamber in fluid communication with both of the first and second retract actuator lines for extending an end effector when the first and second EHSVs pressurize the extend chamber, and for retracting the end effector when the first and second EHSVs pressurize the retract chamber.

Abstract: A heat exchanger includes a plurality of longitudinally-extending first channels and a plurality of second channels fluidly isolated from the plurality of first channels. Each first channels includes a plurality of spiraling internal fins and a plurality of external fins. The internal fins extend from and are integrally formed with the internal walls of the first channel. The external fins connect extend from and are integrally formed with the external walls of the first channels, connecting channels together. The plurality of second channels is defined in part by external walls of the plurality of first channels and the plurality of external fins.

Abstract: A powder recoater for an additive manufacturing machine can include a body, a recoater blade extending downwardly from the body, and at least two distance probes attached to the body and configured to determine a distance to a build plate to determine if a recoater blade is parallel to the build plate and/or if a build plate is level. The at least two distance probes can be touch probes configured to determine if a build plate is contacting one or more of the probes. Any other suitable probe type is contemplated herein.

Abstract: A system includes an actuation pump sub-system (APS) with an inlet configured to feed fuel from a fuel source into the APS, a first outlet configured for connecting the APS in fluid communication with an actuation system to supply fuel flow for actuation, a second outlet feeding into a supply line, and a third outlet feeding into the supply line. A fuel oil cooler (FOC) is included in a first branch of the supply line. The FOC is in fluid communication to receive flow from the second outlet. The APS includes a bypass valve (BPV) in a second branch of the supply line, in parallel with the FOC and in fluid communication to allow flow from the third outlet into the supply line bypassing the FOC. A main pump and control sub-system has a main inlet connected in fluid communication with the supply line downstream of the BPV and FOC.

Abstract: In accordance with at least one aspect of this disclosure, a system includes a first wire configured to electrically connect a valve stop to a voltage source, a second wire configured to connect a valve pin to a negative terminal of the voltage source, such that the valve stop, and a valve flap operatively connected to the valve pin are configured to create a closed valve circuit when the valve flap is in a fully open position with the valve flap contacting the valve stop, and an open valve circuit when the valve flap is not in the fully open position. A meter is operatively connected to measure an electrical characteristic of the valve circuit to determine when the valve flap is in the fully open position based on an open/closed status of the valve circuit.

Abstract: A heat exchanger core comprises a plurality of tubes extending along a first fluid axis, each of the plurality of tubes comprising a leading edge, a trailing edge opposite the leading edge, and a pair of oppositely disposed sidewalls extending from the leading edge to the trailing edge. The leading edge, trailing edge, and the pair of sidewalls define an inner surface and an outer surface of each of the plurality of tubes. Each of a first subset of the plurality of tubes further comprises a roughened region on the outer surface of one of the pair of sidewalls.

Abstract: A system can include a bi-directional converter circuit comprising a plurality of switches and a flying capacitor configured to experience a low voltage or a high voltage, and a control module operatively connected to the plurality of switches to control a state of the plurality of switches. The control module can be configured to receive a sense signal indicative of a flying capacitor voltage and to control the one or more switches of the plurality of switches to charge or discharge the flying capacitor to maintain a target voltage or target voltage range.

Abstract: The present disclosure relates to a winding for an electrical machine. The winding comprises at least one flat conductor having at least one turn to form the winding, and the at least one flat conductor comprises a substantially L-shaped, U-shaped or V-shaped cross-section. The present disclosure also relates to an electrical machine that includes the winding and an aircraft that includes the electrical machine.

Abstract: A system an analog to digital converter (ADC) operatively connected to receive an analog input signal from an input line and to output a digital input signal. A processor is operatively connected to receive the digital input signal from the ADC and to output a digital control signal for controlling a physical system based on the digital input signal. A digital to analog converter (DAC) is operatively connected to receive a copy of the digital input signal put out from the processor, and to output an analog output signal indicative of the copy of the digital input signal put out from the processor. Comparison logic is operatively connected to receive the analog input signal from the input line, to receive the analog output signal from the DAC, and to output an error signal in response to a mismatch between the analog input signal and the analog output signal.

Abstract: A fuel system a main manifold with an inlet and a plurality of main manifold branches. Each valve in a plurality of valves is connected in fluid communication with a respective one of the main manifold branches in the plurality of main manifold branches to receive flow from the main manifold. Each secondary manifold in a plurality of secondary manifolds connects a single one of the valves in the plurality of valves to a pair of secondary manifold branches. Each nozzle in a plurality of fuel nozzles includes a first inlet connected in fluid communication to one of the valves through one of the secondary manifold branches, and a second inlet connected in fluid communication to a different one of the valves through a different one of the secondary manifold branches so each of the fuel nozzles has a redundant connection to the main manifold through two of the valves.

Abstract: In accordance with at least one aspect of this disclosure, a system can include a main board, two or more redundant CPUs for any number of channels operatively connected to the main board and two or more power sources operatively connected to provide power to at least one or more of the two or more CPUs. A respective isolated communications block can be operatively connected to each of the two or more CPUs configured to provide external communications from other components on the main board to a respective CPU.

Abstract: A system can include a first controllable valve configured to output a control pressure on one or more first pressure control lines, a second controllable valve configured to output a control pressure on one or more second pressure control lines, a transfer valve in fluid communication with the first controllable valve and the second controllable valve, and a hydraulic centering system operatively associated with and/or forming part of the transfer valve. The transfer valve can be configured to move between a first position, a second position, and a third position. The hydraulic centering system can be configured to maintain the transfer valve in the first position.

Abstract: A circuit can include a closed loop bus line having a plurality of connections. The circuit can include a plurality of integrated circuits disposed on the close loop bus line at a respective connection of the plurality of connections. One or more of the integrated circuits can be configured to drive a signal on the closed loop bus line. The closed loop bus line can be configured to prevent signal reflection. For example, in certain embodiments, there are no termination resistors at any of the terminations to reduce size, weight, and/or part count of the circuit.

Abstract: A power source selection system can include a primary source line configured to be connected to a primary source having a primary voltage, a backup source line configured to connect to a backup source having a backup voltage, and a voltage divider and limiter connected to the primary source line to receive the primary voltage and to provide an sense signal on a sense line. The system can include a NAND gate connected to the voltage divider and limiter to receive the sense signal. The NAND gate can be configured to provide a gate signal to a gate line based on the sense signal. The system can include a switchover circuit connected to the backup source line and the gate line to receive the backup voltage and the gate signal. The switchover circuit can be configured to output the backup voltage to a switch line in a first state, and to prevent backup voltage to the switch line in a second state.

Abstract: A flapper check valve includes a valve seat body. Two flapper valve portions are each mounted on their own shaft to the valve seat body, and pivotable between open and closed positions. The flapper valve portions pivot in a common rotational direction to the open position and to the closed position. A fluid systems is also disclosed.

Abstract: A vane pump system includes a kidney port plate engaged at an axial end of a rotor and liner. The port kidney plate includes an over vane inlet port configured to be circumferentially aligned with an inlet arc segment of a circumferential cam surface of the liner for ingress of fluid to a plurality of vanes, and an over vane discharge port configured to be circumferentially aligned with a discharge arc segment of the circumferential cam surface for discharging pressurized fluid from the plurality of vanes. The kidney port plate includes at least six kidney ports radially inward from the over vane inlet port and the over vane discharge port. The kidney ports are circumferentially spaced apart from one another. The kidney ports are configured to be radially aligned with vane slots of the rotor for pressure balancing across over vane and under vane ends of the plurality of vanes.