Abstract: An information collection system is configured to collect information related to a bicycle. The information collection system is basically provided with a shift position information acquisition unit and a first controller. The shift position information acquisition unit is configured to acquire shift position information related to a bicycle transmission apparatus having a plurality of shift positions. The first controller is programmed to transmit the shift position information acquired during a certain period.

Abstract: A number of variations may include a product comprising: a bicycle with an integrated folding system comprising at least a main hinge feature in a frame comprising: a first frame component and a second frame component, wherein the first frame component and the second frame component are pivotally attached to each other; a cable which extends through the frame, wherein a first end of the cable is attached to a steerer tube and a second end is attached to a spring-loaded latch pin; and wherein in an unfolded position the spring-loaded latch pin extends between the first frame component and the second frame component which holds the frame together in the unfolded position, and wherein the spring-loaded latch pin is constructed and arranged so that when the main hinge feature is activated, the cable is lifted upward which pulls the spring-loaded latch pin out of the second frame component so that the frame folds together to a folded position.

Abstract: A load transmission includes a left foot placement surface on which a left foot of a driver riding the vehicle is to be placed and a right foot placement surface on which a right foot of the driver is to be placed. The load transmission transmits a load to a left portion of a linkage by way of the left foot placement surface, and transmits a load to a right portion of the linkage by way of the right foot placement surface.

Abstract: A frame for a bike with a plurality of frame units coupled to each other, at least one of the plurality of frame units includes a hollow chamber, and a first partition wall that partitions the hollow chamber into a first chamber unit and a second chamber unit, wherein the first chamber unit includes an opening in a first side of the first chamber unit and an accommodation space to accommodate a battery pack, and wherein the second chamber unit includes a plurality of holes through a first side of the second chamber unit, an interior of the second chamber unit and an exterior of the frame for the bike being in fluid communication through the plurality of holes.

Abstract: A collapsible skateboard includes an upright handle having lower portion on which is fixedly mounted a bracket, a connector having a curved slot having a lower end formed with a horizontal recess, an upper end formed with a vertical recess, and a circular hole under the vertical recess, an adjust pin inserted into the vertical recess of the connector and the elongated hole of the bracket, a pivot pin fitted through the circular hole of the connector and the circular hole of the bracket, a spring having an upper end connected to the adjust pin and a lower end to the pivot pin, and a platform on which is fixedly mounted the connector, whereby the skateboard can be easily folded up as desired.

Abstract: A bicycle apparatus with interchangeable front fork is disclosed. The bicycle comprises a frame and a quick release assembly for securing the removable front fork attachment assembly to the bicycle frame's head tube. The interchangeable front fork attachment assembly and quick release assembly allows for the quick interchanging of front fork with varying attachments which utilize different methods to achieve motion.

Abstract: An air suspension in an embodiment includes: a cylinder; a piston rod; a rod-side member disposed on the lower end side of the piston rod; a diaphragm; an axle-side attachment member having an upper end side of which is fixed to an opening at a lower end of the rod-side member, the axle-side attachment member including a fixing section for fixing the piston rod and an attachment hole joined to an axle; a gas passage formed in the axle-side attachment member, one end of the gas passage being opened to an upper end face of the axle-side attachment member and the other end of the gas passage being opened to a side section of the axle-side attachment member; and a valve section provided at the opening of the other end of the gas passage.

Abstract: A right crank arm assembly for a bicycle, comprises a right crank arm and at least one front sprocket coupled with the crank arm at at least one coupling portion of the crank arm. The front sprocket has an inner side adapted, in use, to face towards the frame of the bicycle and an outer side opposite the inner side. The assembly comprises at least one first crank arm element which acts in contact with the front sprocket on one of said sides and at least one second crank arm element which acts in contact with the front sprocket on the other of said sides. The contact action of the crank arm elements on the two opposite sides of the front sprocket prevents the twisting deformation of the front sprocket during pedaling. Such a deformation would cause a reduction in the transmission efficiency of the right crank arm assembly.

Abstract: A bicycle pedal includes a body having a fixed member, a movable member, a resilient unit and a link respectively connected to each of a first face and a second face thereof. The link and the resilient unit are respectively located on inside of the movable member. The link contacts the movable member. When the cleat of a bicycle shoe pushes the movable member and the link away from the body, the push end of the link swings away from the body and pushes the cleat to disengage from the peal. The link has a restriction portion located corresponding to outside of the end piece. The restriction portion extends from the link and toward the end piece to prevent the bolt from dropping from the end piece.

Abstract: A center-mounted control system for a bicycle includes a torsion detector, a torque transducer, first and second wireless transceiving units, and a control unit. The torsion detector is sleeved on a crank shaft and detects a torque signal of the crank shaft and transmit the detected torque signal to the torque transducer; the torque transducer is fixedly connected to the torsion detector and senses the torque signal transmitted from the torsion detector and sends the torque signal to the first wireless transceiving unit; the control unit receives and processes the torque signal and controls an electrical motor according to the processed torque signal; and a first clutch of the bicycle is sleeved on the crank shaft and is fixedly connected to one end, close to a chain ring, of the torsion detector, and the first clutch of the bicycle is fixedly connected to the chain ring.

Abstract: A bicycle shifting system is basically provided with a first shifting device, a second shifting device and a controller. One of the first shifting device and the second shifting device is mechanically operated, while the other of the first shifting device and the second shifting device is electrically operated. The controller is configured to operate at least one of the first shifting device and the second shifting device in accordance with at least one of a predetermined upshifting route and a predetermined downshifting route.

Abstract: The control system of the vessel with moving underwater wings allows steering with the wings, while in turn the front pair of wings turns in the direction of the turn, the rear pair of wings turns in the opposite direction. The wing pairs settled in the direction of the turn radius. This reduces the turning radius and the roll of the vessel in comparison with conventional steering systems, increasing the maneuvrability of the vessel. The minimal roll of the vessel in the turns allows for an even and maximum distance between the surface and the entire hull of the vessel.

Abstract: A watersports boat includes a hull having an underside extending from a forward bow to an aft transom along a longitudinal centerline. The underside defines a running surface that contacts water when the hull moves therein. The running surface includes a bow section and port and starboard midship running surface sections that flatten moving aft to an aft running surface section. The port and starboard midship running surface sections are separated by a keel member. The keel member has an apex lower than the aft running surface section and that inclines toward the aft running surface section aft the apex and forward a propeller positioned beneath the aft running surface section.

Abstract: The present disclosure relates generally to knee braces for boats. The knee braces described herein are particularly suitable for use with lightweight, inflatable rafts and kayaks, for example packrafts used in backcountry boating. The knee braces include a fabric body and a plurality of adjustable straps configured to attach the fabric body to a side wall of the boat.

Abstract: A method for operating floating vessel wherein the floating vessel comprises a hull having: a bottom surface, a top deck surface, at least two connected sections engaging between the bottom surface and the top deck surface, and at least one fin extending from the hull with an upper fin surface sloping towards the bottom surface and secured to and extending from the hull, the at least one fin configured to provide hydrodynamic performance. The at least two connected sections extend downwardly from the top deck surface toward the bottom surface. The at least two connected sections contain at least two of: an upper portion in section view with a sloping side extending from the top deck section, a cylindrical neck section in profile view, and a lower conical section in profile view with a sloping side extending from the cylindrical neck section.

Abstract: Disclosed herein is a marine vessel, which in one example comprises a substantially continuous deck. Also disclosed is an example with a plurality of parallel longitudinally aligned channels extending from the forward deck to the aft deck. The vessel having a vessel cabin resting on and longitudinally movable upon the deck. The vessel cabin in one example having a plurality of rolling wheels attached thereto; wherein the rolling wheels roll upon the deck and allow longitudinal movement of the vessel cabin between the aft region and the forward region. A drive unit (motor) may be provided. The drive unit optionally mounted to the cabin and in one example having a drive wheel mounted to the drive unit and configured to rotate the drive wheel. The drive wheel(s) contacting the deck such that rotation of the drive wheel repositions the cabin between the aft region and the forward region.

Abstract: A deployable marine system for anchoring a vessel in a body of water and to enable a user to ingress into the vessel from the body of water or egress out of the vessel and into the body of water, the deployable marine system includes an anchor-ladder device and a deployment device. The anchor-ladder device includes a first member and one or more steps, the first member including a first end and a second end. The second end is opposite the first end and is associated with an anchoring component that may anchor the vessel. One or more steps may be attached to the first member. The deployment device may be attached to the vessel, connected to the first member in proximity to the first end, and may deploy the anchor-ladder device into, or retract the anchor-ladder device from, the body of water.

Abstract: An electronically powered, light emitting fin used with a surfboard or paddleboard, or similar water sports board. The fin is configured to be attached to the water sports board to provide illumination under the board when using the device. The lighted fin may be particularly useful when using the water sports board at night to illuminate water beneath the board.

Abstract: A system and method for performing a marine seismic survey of a subsurface. The method includes deploying under water, from a deploying vessel, an autonomous underwater vehicle (AUV); recording with seismic sensors located on the AUV seismic waves generated by an acoustic source array; instructing the AUV to surface at a certain depth relative to the water surface; recovering the AUV by bringing the AUV on a recovery vessel; and transferring recorded seismic data to the recovery vessel.

Abstract: A submarine structure provides a submarine in which the interior thereof is formed with an accommodation space and an electricity storing chamber connected to the accommodation space and having a battery and a power set having a propeller, and includes: at least one pipe, having the interior installed with at least one cable; at least one floating member, connected to another end of the at least one pipe; at least one energy supplier, disposed and in the floating member or the accommodation space and located at a relatively higher location inside the floating member or the accommodation space; and at least one control board, installed in the accommodation space of the submarine or the floating member, wherein the control board is connected to the energy supplier through the cable of the at least one pipe for providing power and maintaining communication and control.

Abstract: A hull mold of an aquatic vessel may include a keel pad sectional extended from a hull planing surface to a location on the hull mold at which a propeller shaft exits a propeller shaft tunnel at an aft transom edge of the hull mold and/or at a forward portion of the keel pad sectional, with sides of the propeller shaft tunnel formed into directional ports to increase a flow of water into the propeller shaft tunnel.

Abstract: A deflector control portion in a jet propulsion boat causes a deflector to swing by controlling a deflector drive mechanism in response to an operation of a shift operating portion. The deflector control portion causes the deflector to move to a first trim position when the shift operating portion is switched to a forward movement shift position. The deflector control portion causes the deflector to move to a second trim position when the shift operating portion is switched to an operating shift position.

Abstract: A trolling motor assembly includes a base and an attached cradle. A transmission housing is coupled to the base by a pivot pin defining an axis about which the transmission housing pivots. A shaft is supported by the transmission housing and moves relative to the transmission housing in a direction which is parallel to a central axis of the shaft. The shaft is also rotatable with respect to the transmission housing about the central axis. A thrust motor is attached to and moves and rotates with the shaft. The assembly is movable from a deployed position, in which the shaft central axis is aligned vertically, the transmission housing is locked in an upright position, and the thrust motor is below water, to a stowed position, in which the shaft central axis is aligned horizontally, the transmission housing is pivoted onto its side, and the thrust motor rests in the cradle.

Abstract: A system for mounting an outboard motor propulsion unit to a marine vessel transom includes a support cradle having a head section coupled to a transom bracket and a pair of arms extending aftward from the head section and along opposite port and starboard sides of the propulsion unit. A pair of upper mounts is provided, each upper mount in the pair coupling a respective arm to the propulsion unit aft of a center of gravity of an engine system of the propulsion unit. A pair of lower mounts is also provided, each lower mount in the pair coupling the propulsion unit to the transom bracket. The pair of upper mounts is located aft of the pair of lower mounts when the propulsion unit is in a neutral position, in which the propulsion unit is generally vertically upright and not tilted or trimmed with respect to the transom.

Abstract: An outdrive for a marine vessel, such as a watercraft having an inboard engine, is provided. The outdrive can include a standoff box joined with a drive unit having a driveshaft that rotates in response to rotation of an input shaft coupled to an engine within a hull of the watercraft. The drive unit includes a propeller shaft that rotates in response to rotation of the driveshaft, and an associated propeller. The drive unit is vertically movable from a raised mode to a lowered mode, in which the propeller shaft is a preselected distance from a bottom of the boat hull, thereby lowering a thrust point produced by the propeller, all while the watercraft is moving through water and while the propeller is producing thrust. A related method and standoff box are also provided.

Abstract: An engine control device is provided with a main operation unit, an auxiliary operation unit, a changeover switch, and an engine control unit. The main operation unit is capable of performing an operation of changing a rotation speed of a propulsion engine mounted on a ship. The auxiliary operation unit is capable of performing an operation of changing the rotation speed of the engine instead of the main operation unit. The changeover switch is capable of performing an operation of switching between a main ship handling state in which the rotation speed of the engine can be changed by operating the main operation unit and an auxiliary ship handling state in which the rotation speed of the engine can be changed by operating the auxiliary operation unit. The engine control unit stops the engine when the changeover operation unit is operated to switch from the auxiliary ship handling state to the main ship handling state.

Abstract: The invention generally relates to a remote controlled boat system. In certain embodiments, the system includes a boat having a first central processing unit operably coupled to a communication unit and a first global positioning unit operably coupled to the first central processing unit. The system also includes at least one controller configured to control the boat via remote communication with the first central processing unit via the communication unit of the boat, the controller including a second central processing unit operably coupled to a second global positioning unit.

Abstract: A novel design of a hydraulic steering arrangement for a thruster of a marine vessel is specifically designed for thrusters intended to operate in an arctic environment where ice is present. To meet the arctic demands the steering arrangement is provided with a cross-over safety block arranged close to the hydraulic steering motor for absorbing the torque subjected to the thruster by ice for instance.

Abstract: Various embodiments for measuring and interpreting a vessel operator's intent and control inputs are disclosed. Various stations on a vessel comprise user control devices to receive vessel control commands from a vessel operator in conjunction with associated transducer information capturing physical conditions or attributes of the operator at, or proximate to, one of the user control devices. A processor determines whether the vessel control command was deliberate, based on the physical condition or the attribute captured by the transducer. Upon determination of a valid user control input, the processor optionally performs transformation of the user vessel control command based on an operator identity and vessel environmental factors, and then sends a corresponding control command to one or more vessel physical control devices, such as a rudder or an engine.

Abstract: An intelligence, surveillance, and reconnaissance system is disclosed including a ground station and one or more aerial vehicles. The aerial vehicles are autonomous systems capable of communicating intelligence data to the ground station and be used as part of a missile delivery package. A plurality of aerial vehicles can be configured to cast a wide net of reconnaissance over a large area on the ground including smaller overlapping reconnaissance areas provided by each of the plurality of the aerial vehicles.

Abstract: A device according to the present invention comprises: a tubular body (2) and a first attachment means (6), a piston (30) provided with a rod (12) connected to a second attachment means (10), the piston (30) sliding inside the tubular body (2) and defining inside said body a working chamber filled with hydraulic fluid, an accumulator comprising a rigid shell (20) inside of which a separation means (40) is located, defining a compensation chamber (42) that is filled with hydraulic fluid and is in communication with the working chamber, and a chamber (47) filled with pressurized gas, the rigid shell (20) being a metal shell produced by means of welded assembly and the accumulator being made such as to obtain an entirely welded enclosure (47) containing the gas.

Abstract: A system for shielding of at least one component (28) within an aircraft (10) includes a floor panel disposed at least partially between joists (38) supporting a floor (30) within the aircraft and a ground plane (44) connected to a bottom surface of the floor panel. The ground plane extends at least partially between adjacent joists. At least one bracket (52) electrically connects the ground plane to at least one of the joists.

Abstract: Adjustable height control stick assembly for dual control of aircraft includes a single control stick for longitudinal and lateral orientation of the aircraft with the height adjustment allowing for correction of position prior to flight. The stick is connected to appropriate linkages to move the ailerons and elevator of an airplane or the rotor blades of a helicopter. When either the pilot or the copilot is flying the grip for the other is at a different height to that for normal operation. The invention replaces and makes adjustable the grip so that height of the grip of both pilot and copilot are the same as if they were flying and in control of the aircraft.

Abstract: An inceptor apparatus (10) for controlling a vehicle, in particular an aircraft comprises a control stick (15) for operation by a user and a user feedback generator (28) coupled to the control stick and configured to receive signals from a vehicle condition indicator (40) remote from the inceptor apparatus. The apparatus also has a first vehicle condition sensor (54,56) dedicated to the operation of the inceptor apparatus. In a first mode of operation, the user feedback generator (28) is operable to generate tactile feedback to the user via the control stick in dependence upon signals received from the vehicle condition indicator (40). In a second mode of operation, in the event that no signal is received from the vehicle condition indicator (40), the user feedback generator (28) is operable to generate tactile feedback to the user via the control stick in dependence upon signals received from the first vehicle condition sensor (54,56).

Abstract: This disclosure describes systems, methods, and apparatus for automating the verification of aerial vehicle sensors as part of a pre-flight, flight departure, in-transit flight, and/or delivery destination calibration verification process. At different stages, aerial vehicle sensors may obtain sensor measurements about objects within an environment, the obtained measurements may be processed to determine information about the object, as presented in the measurements, and the processed information may be compared with the actual information about the object to determine a variation or difference between the information. If the variation is within a tolerance range, the sensor may be auto adjusted and operation of the aerial vehicle may continue. If the variation exceeds a correction range, flight of the aerial vehicle may be aborted and the aerial vehicle routed for a full sensor calibration.

Abstract: An active wing extension includes a body portion substantially parallel to a wing of an aircraft, as if it were an extension of the wing. The body portion is attachable to an aircraft wing and includes multiple controllable airflow modification devices coupled thereto. By virtue of having multiple controllable airflow modification devices, the wing extension is capable of adjusting control surfaces of the multiple controllable airflow modification devices in response to in-flight conditions, to reduce wing loads, improve wing fatigue characteristics, increase range, and/or increase efficiency.

Abstract: An aircraft is provided and includes one or more main rotors, one or more and propellers including blades that are rotatable about a rotational axis, a pitch of each of the blades being controllable, and a flight control computer disposed to control the pitch of each of the blades to reduce propeller blade pitch angles in an event of an engine failure.

Abstract: A hybrid support ring comprises a suspender and a belt, the suspender defined by a flange and a leg rearwardly extending having a lug, the suspender also extending circumferentially, the suspender formed of a first material, the belt extending circumferentially and disposed in the lug, the belt being formed of a second material.

Abstract: A motor vehicle system includes a motor vehicle including an aircraft landing portion, and an actively propelled unmanned aircraft configured to be supported on the aircraft landing portion. The vehicle and aircraft are configured such that the vehicle can provide at least one of fuel and electrical energy to the aircraft while the aircraft is supported on the aircraft landing portion.

Abstract: A drone launch system includes a canister defining an internal cavity, and a drone positioned within the internal cavity in a stowed state. The drone is configured to be ejected from the canister and transition from the stowed state into a deployed state outside of the canister. A method for launching a drone, the method includes positioning the drone in a stowed state in an internal cavity of a canister, ejecting the drone from the canister, and transitioning the drone into a deployed state after the ejecting operation.

Abstract: An unmanned aerial vehicle (UAV) can be configured for crop height estimation. In some examples, the UAV includes an aerial propulsion system, a laser scanner configured to face downwards while the UAV is in flight, and a control system. The laser scanner is configured to scan through a two-dimensional scan angle and is characterized by a maximum range. The control system causes the UAV to fly over an agricultural field and maintain, using the aerial propulsion system and the laser scanner, a distance between the UAV and a top of crops in the agricultural field to within a programmed range of distances based on the maximum range of the laser scanner. The control system determines, using range data from the laser scanner, a crop height from the top of the crops to the ground.

Abstract: An aerodynamic lifting device comprises a chassis (200); a rotor (120) having a rotational axis (R) and a plurality of rotor blades (123) disposed in an annular ring about the rotational axis (R) supported by the chassis (200); and a torque transmission means (126,130,139) to provide tractive force for rotating the rotor (120). The torque transmission means (126,130,139) co-operates with at least one complementary and circumferentially extending drive surface (126a, 126b) of the rotor (120) to transmit tractive force as tangential forces and resultant torque sufficient to drive the rotor (120) and thereby generate lift. The aerodynamic lifting device may be used in airborne craft which may be deployed for waterborne use with a buoyant chassis (200), especially of toroidal shape, for elevating the rotor (120) above a water surface (300) during take off and landing.

Abstract: An unmanned aerial vehicle (UAV) can deliver a package to a delivery destination. Packages delivered by a UAV may be lowered towards the ground while the UAV continues to fly rather than the UAV landing on the ground and releasing the package. Packages may sway during lowering as a result of wind or movement of the UAV. A package sway may be monitored and mitigated by rapidly paying out a tether, when using a winch mechanism, to dissipate the energy of the sway as downward energy. Further, the UAV may navigate in the direction of the sway or reduce the altitude of the UAV to dissipate the energy of the sway. Open-loop and/or closed loop drop techniques may be utilized to lower a package from the UAV, and the package may be released in the air or on the ground.

Abstract: Systems and methods include UAVs that serve to assist carrier personnel by reducing the physical demands of the transportation and delivery process. A UAV generally includes a UAV chassis including an upper portion, a plurality of propulsion members configured to provide lift to the UAV chassis, and a parcel carrier configured for being selectively coupled to and removed from the UAV chassis. UAV support mechanisms are utilized to load and unload parcel carriers to the UAV chassis, and the UAV lands on and takes off from the UAV support mechanism to deliver parcels to a serviceable point. The UAV includes computing entities that interface with different systems and computing entities to send and receive various types of information.

Abstract: A lighting apparatus includes: a linear light source having an elongated shape; and an optical component which transmits light emitted from the linear light source. The optical component has an entrance surface where the light emitted from the linear light source enters and (ii) an exit surface where the light which has entered the entrance surface exits. The optical component includes, on the exit surface, a light diffuser row including a plurality of light diffusers which are arranged in a line. In a plan view of the exit surface, a first direction in which light-emitting elements included in the linear light source are arranged intersects with a second direction in which the light diffusers are arranged.

Abstract: A system and method for regulating pressure inside a vehicle (“cabin pressure”) is disclosed. The system can include a forward gate and an aft gate that can be moved from a closed position to an open position to release cabin pressure in a controlled manner. The forward gate, the aft gate, or both can comprise an interior cavity and one or more permeable surfaces. When open, or partially open, an airflow can be created by a pressure differential between the cabin pressure and the pressure outside the vehicle (“atmospheric pressure”). At least a portion of the airflow can flow through the one or more permeable surfaces and the hollow cavity of the forward gate, the aft gate, or both to promote laminar flow through the gates and into the atmosphere alongside the vehicle (e.g., an aircraft fuselage). In this manner, flow efficiency can be increased and noise reduced.

Abstract: A water-inflow prevention device is provided by installing a closing lid 6 for blocking a duct 2 of an air pressure regulating valve 1, which regulates air pressure inside a cabin 101. A buoyant body 9 is attached to the disc-shaped closing lid 6 installed to the duct 2 so as to be rotatable around a rotation shaft 7. The buoyant body 9 receives a buoyant force from water when immersed in the water. Since the side of the closing lid 6 in which the buoyant body 9 is attached is thereby floated in the water, the closing lid 6 automatically rotates around the rotation shaft 7 so as to close a ventilation port 2a.

Abstract: A nacelle for an aircraft turbojet engine includes: a substantially cylindrical internal envelope, a substantially cylindrical external envelope, a downstream partition wall and an upstream partition wall secured to the cylindrical internal envelope and a front lip disposed forward of the upstream partition wall. The cylindrical internal envelope includes an upstream portion including an acoustic shroud connected, by an attachment flange, to a downstream portion including a fan casing. In particular, the front lip is extended and disposed over the upstream partition wall by presenting a downstream edge between the upstream and downstream partition walls in order to be secured to a homologous edge of the cylindrical external envelope so as to arrange a maintenance access to the attachment flange.

Abstract: Plenums for bifurcated ducts and bifurcated ducts are provided for stabilizing flow therethrough. The plenum comprises an outer cylindrical body intersected by a pair of exhaust duct stubs that are configured to be coupled to a corresponding pair of exhaust ducts and an inner body. The outer cylindrical body includes an axial rear end portion. The inner body is disposed in the axial rear end portion and increases in diameter in the aft direction. The inner body comprises one of a generally axi-symmetrical inner body or a non-axi-symmetrical inner body. The bifurcated duct comprises the plenum and the pair of exhaust ducts. Exhaust systems are also provided.

Abstract: An aircraft fuel tank arrangement for the relief of a pressure differential between the interior of the aircraft fuel tank and the ambient atmosphere is provided. The aircraft fuel tank arrangement comprises a removable cartridge received within a cartridge-receiving body located at least partially in the fuel tank, said cartridge comprising a first burstable member operable to rupture in the presence of a pressure differential between the interior of the aircraft fuel tank and the ambient atmosphere which is greater than a predetermined pressure differential.