An energy storing device is disclosed. In the energy storing device of the present invention, energy from an energy generating unit is stored in the form of spring torsion and then is output steadily. The energy storing device of the present invention includes a plurality of cog-wheels, a plurality of torsion magnitude limiting units, a plurality of single-directional input bearings, a plurality of energy storing units and a plurality of speed enhancing cog-wheels. Each of the energy storing units includes at least two end rotational disc portions, which are connected with each other co-axially. A leaf spring unit is provided between each pair of rotational disc portions and one end of the leaf spring unit is bent in an opposite direction. In addition, the energy storing units may be connected in series or in parallel to increase the efficiencies in energy storage and energy output.

Gravity powered electrical energy generators, particularly for producing lighting is disclosed. The apparatus has a support frame (1, 30) in which a series of gears and a gear-driven generator (20) are mounted. The power to drive the most upstream gear (2) is provided by a weight suspended from a point to one side of the axis of rotation of gear (2). The drive gear of the furthest downstream gear has no teeth so that the final contact between the drive gear and the shaft of the generator (20) is frictional. The gear ratio of the final downstream gear is at least 25. When used for lighting, the apparatus may include one or more high brightness LEDs (40) mounted on the housing (30). By suitable choice of gear ratios, the device may produce thirty minutes of illumination while allowing a 10 kilogram weight to fall through a distance of 1.8 meters.

A method for printing a digitally-stored image on the surface of a cylindrical object comprises the steps of axially moving the object along a line of travel that is aligned with the object's long axis until it is underneath one or more printheads, each of which have a plurality of ink nozzles that may be arranged in one or more columns while simultaneously rotating the object with respect to the printheads and simultaneously causing a pre-determined number of nozzles to eject ink onto the surface of the object.

A printing device includes: a main body having an attachment surface; first and second mounting sections formed in the attachment surface respectively for detachably receiving first and second cassettes; first and second print parts; a body cover having an opposing surface; first and second pressing parts protruding from the opposing surface respectively toward the first and second mounting sections; first and second engaging parts provided at the main body; and third and fourth engaging parts provided at the body cover and engageable with the first and second engaging parts. A first center of gravity of load that the mounted first cassette applies to the first pressing part and a second center of gravity of load that the mounted second cassette applies to the second pressing part are located within a specific area on the opposing surface defined by virtual lines passing through locations on the third and fourth engaging parts.

A controller in a one-side printing mode moves movable rollers to form a one-side printing route and moves a second head unit so that the second head unit faces a front side of a web. The controller then controls a first head unit and a second head unit to print images of respective pages on the front side of the web while transferring the web at a transfer speed twice as fast as that in a both-side printing mode.

A method for controlling a print device by generating a firing encoder signal from varying one or more characteristics of a reference signal where, the one or more characteristics are varied based on at least the position of a print medium at a reference time. The firing encoder signal is used to synchronize firing of at least one print head of the print device after the reference time.

An elastic roller includes: a roller shaft; and an elastic member. The elastic roller includes an inner layer side elastic member, and a coating layer. The inner layer side elastic member has a rubber hardness of 30 to 80 degrees that is measured by a durometer type A in accordance with the standard of JIS K 6253. The inner layer side elastic member has a tear strength of 25 N/mm or more that is measured using an unnicked angle-shaped test piece in accordance with JIS K 6252. The coating layer is made of silicone resin, and has a thickness of 10 to 100 μm. The silicone resin has hardness of 20 degrees or less that is measured using a spring-based Asker C type in accordance with SRIS 0101 standard. The inner layer side elastic member has a plurality of internal grooves along a circumferential direction. Each of the internal grooves has a width of 25 to 1,300 μm, and has a depth of 25 to 500 μm. Each of the internal grooves has a V-shaped in cross section and has a groove angle of 50 to 120 degrees.

A recording paper cutting device enables cutting of a boundary between a first area of a recording paper and a second area of the recording paper placed at an upstream side of the first area, so that the first area is separately discharged from the second area after the first area is printed. The recording paper cutting device includes first and second cutting parts. The first cutting part of the second cutting parts moves in an approaching or departing direction so that the boundary is cut. The first cutting part includes a first cutting surface inclined by a first angle in the departing direction from the second cutting part and a second cutting surface that extends from the first cutting surface and is inclined by a second angle, which is smaller than the first angle, in the departing direction from the second cutting part.

A printing device includes a roller; a stepper motor; a head; and a controller, The roller is for conveying a printing medium in a conveying direction. The stepper motor is configured to rotate in synchronization with a pulse signal and rotate the roller. The head is configured to perform printing on the printing medium conveyed by the roller. The controller is configured to perform: decelerating the stepper motor from a first speed to a second speed; identifying a rotational speed of the stepper motor during deceleration of the stepper motor; performing synchronous printing in which the head is driven at timing in synchronization with the pulse signal when the rotational speed is greater than or equal to a prescribed speed; and performing timer printing in which the head is driven at a prescribed period when the rotational speed is less than the prescribed speed.

Disclosed is a device for encoding information written on a readable surface, the device including a device housing containing at least one ink reservoir, an ink dispensing tip in communication with said at least one ink reservoir; and ink stored in the at least one ink reservoir and configured to flow from the ink dispensing tip, the ink being encodable to include supplemental encoded information, the supplemental encoded information being detectable by at least one detecting sensor when dispensed on the readable surface, wherein the readable surface is any surface that will accept the ink.

Apparatuses, methods, and computer program products are described herein. An example disclosed printing device includes a printer body; a cradle engagement surface configured to interface with a cradle, the cradle engagement surface defining a first recess and a second recess disposed proximate a first side of a battery compartment; and a bumper attachment extending from the printer body and disposed proximate a front side of the printer body, the bumper attachment defining at least two capture cavities structured to slideably receive reciprocally structured first and second printer capture flanges extending from the cradle.

Examples of a printing device, a method for use in a printing device, and a machine readable non-transitory storage medium including instructions relating to a printing device that are executable by a processor are disclosed herein. An example of the machine readable non-transitory storage medium includes instructions relating to a printing device that, when executed by a processor, cause the processor to: segment data for an image into a plurality of positions, analyze performance data regarding an actual portion of the image formed by each of a plurality of print heads, arrange the segmented image data for each portion of the image based on the performance data for each of the print heads, and transmit the arranged image data to each of the print heads so that each print head forms a correct portion of the image.

A RIP device which receives image data and print media designation from a PC performs a data generating process by adopting a process parameter corresponding to the designated print media among process parameters stored in a loop-up table (LUT). A printer performs a printing process by adopting a printing parameter corresponding to the designated print media among the printing parameters stored in the LUT. The process parameter and the printing parameter are associated by a media number which is applied by a management server.

The print management device includes a print management information acquisition unit that acquires print management information including first information indicating quality of a printed material printed in a print job during execution and second information indicating an evaluation index of the printed material, different from the first information, in the print job during execution, a print management request acquisition unit that acquires request information indicating a request relating to print management of the printed material in the print job, a request evaluation unit that evaluates the degree of satisfaction of the printed material printed in the print job for the request relating to the print management indicated by the request information, based on the print management information, using one or more evaluation references, and a printing condition change determination unit that determines whether change in printing conditions in the print job during execution is necessary, based on an evaluation result.

Disclosed is a device for encoding information written on a readable surface, the device including a device housing containing at least one ink reservoir, an ink dispensing tip in communication with said at least one ink reservoir; and ink stored in the at least one ink reservoir and configured to flow from the ink dispensing tip, the ink being encodable to include supplemental encoded information, the supplemental encoded information being detectable by at least one detecting sensor when dispensed on the readable surface, wherein the readable surface is any surface that will accept the ink.

A method for marking references on a flat article includes providing a model having at least a through-opening and exhibiting the same peripheral profile as a flat article to be marked; detecting the peripheral profile of the model and storing that profile in a memory; detecting a profile of the through-opening and the relative positioning with respect to a reference system; detecting a peripheral profile of the flat article; replicating the peripheral profile of the model so as to superpose it on the peripheral profile of the flat article; replicating also the profile of the through-opening of the detected model, taking account of the relative positioning with respect to the reference system and of the positioning of the peripheral profile of the model with respect to the peripheral profile of the flat article. Contactless marking of at least a reference on the flat article is made at the profile of the through-opening which has been replicated.

A judgment device includes a residual capacity acquisition section adapted to obtain a remaining battery power of a battery as a power source of a printer, an arithmetic section adapted to calculate a predicted consuming capacity of the battery consumed by execution of a print job, and a judgment section adapted to judge whether or not the battery has the remaining battery power, with which the printer can complete the print job, based on the remaining battery power and the predicted consuming capacity.

An exposure device includes: a board on which light emitting elements are arranged; an optical system disposed opposite to the board; a support member which supports the board and the optical system; and a cured body disposed on the support member and including a board contact surface to come into contact with the board, wherein the cured body is formed by curing a deformable material.

A piezoelectric element includes: a titanium-containing adhesion layer, a lower electrode, a PZT-based piezoelectric film, and an upper electrode, which are sequentially provided on a silicon substrate, in which the lower electrode includes a columnar structure film consisting of a large number of columnar crystals which are grown from a surface of the titanium-containing adhesion layer and have a platinum group element as a primary component, and an adhesion layer component diffused from the titanium containing adhesion layer and oxygen diffused from the piezoelectric film side, which are present in the columnar structure film, and a main column diameter of the columnar crystal of the columnar structure film is 50 nm or more and 200 nm or less.

The invention provides a new method for the safe storage and drying of a helmet and related accessories (spare helmet face shield, sunglasses, goggles, primary gloves, secondary gloves, chin curtain, breath deflector/guard, helmet screws, neck brace, knee pads, elbow pads, chest protector, keys, and remote control gate/garage openers) employed in activities in which a helmet is utilized. The device is suspended utilizing various length interchangeable hanging straps possessing varied attachment methods to accommodate various hanging locations. The side connected hanging straps attach at an angle to the front opening so that the front opening is directed at an upward facing angle off of the vertical plane and a center angle adjustment and interlocking strap is utilized to set a preferred angle and interlink multiple devices hung vertically one under another. The angled orientation enables the device to be bumped or swung without concern that the helmet or other items stored therein will fall out. The shape and flexible nature of the device allows the sides to close in toward the helmet under the weight of a resting helmet. The device employs multiple attachment points and pockets to accommodate the related accessories and their related locations are such that they provide for the easy access to storage and removal based on frequency of use and order in which stored and removed.

A fast detachable side wheel device, comprising: a first wheel cover, a second wheel cover, a wheel body, and a movable component. Firstly, wheel body is fixed in first receiving groove of second wheel cover as a replaceable component. Through positioning of a dovetail groove of first wheel cover and a dovetail tenon of second wheel cover, thus vibration, collision, or detachment of wheel body due to outside force can be avoided. Then, the movable component is used to control the positioning or detaching states between first wheel cover and second wheel cover, thus achieving fast and labor saving assembly and detachment of side wheels.

The sports bag with chair device provides a rigid front connected to a pliable rear, a top spaced apart from a bottom, and a pair of spaced apart sides, a top handle disposed within the top pliable rear, a pair of spaced apart wheels disposed on the rigid front bottom, the wheels extended forwardly from the front, an upper compartment disposed within the pliable rear top, a lower compartment disposed rearwardly and downwardly within the pliable rear, a closure selectively closing each compartment, a recess disposed about midway within the rigid front, a pivoted chair disposed within the recess, the pivoted chair selectively positioned within and without the recess, and a pair of spaced apart telescopic legs pivotally affixed forwardly and downwardly on the pivoted chair.

The invention provides a carry-on wheeled luggage (1) for photographic equipment that has an interior compartment (80) deep enough to accommodate a large article of photographic equipment such as at least a 400 mm 2.8 f-stop aperture telephoto lens.

A case for a portable electronic device such as cell phones, cameras, MP3 players and PDAs wherein said case includes material at the corners to provide protection to the electronic device. To reduce bulk at the corners and allow the material forming the case to conform with the contours of the device, the protection at the corners includes strips of material defining apertures there between. The apertures provide reduction in bulk and allow the case to conform to the corners of the device therein. Alternately, the protection at the corners can be provided by other structures co-molded into the corners of the cases. Such structures include material that is of a reduced thickness than other material used in the case, or structures that are formed to conform to the corners of the case. Such structures can be joined to the material forming the panels of the case by co-molding.

The present invention provides a new and useful apparatus for charging battery powered electronic devices using a rolling means. The rolling means transfers mechanical energy from a plurality of wheels to a generator by way of a gear ratio. The generator in turn yields electrical energy that is later transformed via integrated circuitry into viable power for the purposes of charging an optional internal batter or that of an attached device. This apparatus does not limit the user's mobility and can be used in everyday settings. The apparatus can be an integral part of a piece of luggage or added to an existing hand cart. Additionally, the apparatus can have a connection for a DC input to charge the internal battery when the apparatus is not in motion.

An expandable item carrying device facilitates carrying items such as groceries and the like. The device includes a container having a bottom wall and a perimeter wall coupled to and extending upwardly from a perimeter edge of the bottom wall defining an interior space. A top edge of the perimeter wall defines an opening into the interior space. The perimeter wall has a pair of opposed ends sides and a pair of longitudinal sides extending between the opposed end sides. The longitudinal sides and the bottom wall are compactable along a longitudinal axis of the bottom wall. A primary handle comprises opposed ends coupled to a first one of the longitudinal sides of the perimeter wall.

A gyro sensor according to the invention includes a first mass portion including a first detection portion, a second mass portion including a second detection portion, first drive portions vibrating the first mass portion in a direction of a first axis, and a force conversion portion fixed to an anchor portion. The first mass portion and the second mass portion are connected with the force conversion portion. The force conversion portion is displaced with the anchor portion as an axis, and vibrates the second mass portion in a direction of a second axis crossing the first axis in a plane view.

An electronic device includes a base body, a functional element that is placed on the base body, and a lid body, formed from silicon, that is placed over the base body so as to cover the functional element. A hole portion and a sealing member that closes the hole portion are disposed in the lid body, in the hole portion, the area of a second opening disposed on a side opposite to a first opening is larger than the area of the first opening disposed on the base body side, and the ratio of the volume of the sealing member to the volume of the hole portion is equal to or higher than 35% and is equal to or lower than 87%.

A micromechanical component is described having a substrate which has at least one stator electrode fixedly mounted with respect to the substrate, a movable mass having at least one actuator electrode fixedly mounted with respect to the movable mass, and at least one spring via which the movable mass is displaceable. The movable mass is structured from the substrate with the aid of at least one separating trench, at least one outer stator electrode spans at least one section of the at least one separating trench and/or of the movable mass, the at least one actuator electrode protrudes between the at least one outer stator electrode and the substrate, and at least one inner stator electrode protrudes between the at least one actuator electrode and the substrate. A related manufacturing method is also described for a micromechanical component.

The present invention is a method and apparatus for acoustically manipulating one or more particles.

A method for ultrasonically inspecting components with wavy or uneven surfaces. A multi-element array ultrasonic transducer is operated with a substantial fluid layer, such as water, between the array transducer and the component surface. This fluid layer may be maintained by immersing the component in liquid or by using a captive couplant column between the probe and the component surface. The component is scanned, measuring the two dimensional surface profile using either a mechanical stylus, laser, or ultrasonic technique. Once an accurate surface profile of the component's surface has been obtained, data processing parameters are calculated for processing the ultrasonic signals reflected from the interior of the component that eliminate beam distortion effects and reflector mis-location that would otherwise occur due to the uneven surfaces.

A system is provided for inspecting a workpiece that includes a workpiece defect and a workpiece surface. The system includes a laser pointer connected to an ultrasonic inspection system. The ultrasonic inspection system includes an ultrasonic transducer that directs sound waves to the workpiece defect, where the sound waves contact the workpiece surface at a workpiece surface location. The laser pointer directs a laser beam against the workpiece surface to visually annunciate the workpiece surface location.

The present invention employs a photoacoustic measuring apparatus including: a laser light source; a forming unit for forming a second light beam by dividing or deforming a laser light beam; an optical member for guiding the second light beam to the surface of a subject; a probe for obtaining a photoacoustic wave generated when the subject is irradiated with the second light beam; and a buffering member that contacts the surface of the subject and transmits light, wherein the optical member overlaps areas of the second light beam having a small light intensity on the surface of the subject, the probe and the optical member are positioned on an identical side of the buffering member relative to the subject, and the optical member refracts the second light beam such that the second light beam enters the subject through the buffering member while avoiding the probe.

One embodiment of the invention provides a system for identifying an anomalous movement of a reciprocating element in a reciprocating device, the system comprising: at least one sensing device for sensing a vibration signal of the reciprocating element; a processing apparatus for separating the vibration signal into a first component having a first frequency range and a second component having a second frequency range different than the first frequency range; and a device for at least one of analyzing or displaying at least one of the first or the second components of the vibration signal, wherein the vibration signal includes positional data of the reciprocating element along at least one axis of the reciprocating element.

Apparatus configured detect a physical quantity, for example a density, of a flowing fluid, the apparatus including: a sensor body (2) configured to extend into the flowing fluid, the sensor body comprising a fiber Bragg grating (FBG) of a fiber Bragg grating sensor (3, 7, FBG), for generating a detector signal relating to vibration of at least part (2B) of the sensor body (2); anda processing unit, configured to process the detector signal, and to determine the physical quantity based on detected vibration at a mechanical eigenfrequency of the flexible part (2B) of the sensor body (2).

A device and method for measuring the clamping force a machine tool exerts on a tool holder that includes a piston or cylinder body defining a bore that slidably receives a piston. A fluid filled pressure chamber is defined between the piston and the body and a pressure gauge carried by the piston communicates with the pressure chamber such that movement in the piston in at least one direction exerts compressive forces on the fluid in the pressure chamber which is communicated to the pressure gauge. A retention knob is coupled to the piston and is engageable by the machine tool such that the clamping force exerted by the machine tool is transmitted to the piston. Hex-shaped structure on the piston that is received by a complementally formed recess in the cylinder body inhibits relative rotation between the piston and the body and facilitates installation and removal of the retention knob. A pin forming part of the piston is engageable by a pin receiving recess in the piston body and ensures a predetermined orientation between a shank portion and the piston body, during assembly.

Embodiments of the present invention provide an integrated circuit system including a first active layer fabricated on a front side of a semiconductor die and a second pre-fabricated layer on a back side of the semiconductor die and having electrical components embodied therein, wherein the electrical components include at least one discrete passive component. The integrated circuit system also includes at least one electrical path coupling the first active layer and the second pre-fabricated layer.

A method of processing downhole measurement data includes: receiving formation measurement data generated by a downhole tool during a logging-while drilling operation over a selected time period; receiving a measured depth corresponding to the selected time period based on data taken at a surface location; receiving tool rotation data generated by measurements of a rotational rate of the downhole tool taken by a downhole sensor during the selected time period; calculating a new depth of the tool as a function of time over the selected time period based on a relationship between the tool rotation data and the measured depth; and correcting an original depth of the measurement data with the new depth.

Remotely readable valve position indicators and related methods are described. An example apparatus in accordance with the teachings of this disclosure includes a valve body, a valve stem and a fluid flow control apparatus coupled to the valve stem. The fluid flow control apparatus is longitudinally displaceable between a first position and a second position to control fluid flow through a flow aperture of the valve body. The apparatus also includes a valve position indicator including an identifier device coupled to the valve stem. In the first position, the wireless identifier device associated with a first value indicative of the first position of the fluid flow control apparatus. In the second position, the wireless identifier device associated with a second value indicative of the second position of the fluid flow control apparatus.

A parking sensor device has a casing, a front cover, a sensor module and an assembling clamp. The casing has two first hooking elements. The front cover is mounted on the casing. The sensor module is mounted in the casing and the front cover. The assembling clamp detachably engages the casing and has two second hooking elements. The second hooking elements selectively hook the first hooking elements of the casing respectively. The casing and the assembling clamp are engaged quickly with each other, thereby facilitating the easy fabrication of the parking sensor device and improving the convenience of maintenance of the parking sensor device.

Device (10) for vehicle driving evaluation comprising: A means (11) to obtain at least one physical parameter whereby it possible at any time to determine the value of the speed and instantaneous acceleration of a traveling vehicle;A calculation and comparison unit (12) whereby it is possible, from said physical parameter, to calculate an effective parameter that depends on said instantaneous acceleration and to compare said effective parameter with a reference parameter;A driving evaluation unit (13), whereby it is possible to generate a vehicle driving energy score by measuring the variance between said effective parameter and said reference parameter. Corresponding vehicle driving evaluation process.

A method of calculating a 3-D geologic model in real time using, as input, 2-D geologic data. The 3-D is used for conducting further drilling operations. The model may be updated in real time using additional measurements obtained during drilling operations.

An ultrasonic sensor includes: a substrate; an ultrasonic transducer disposed on the substrate, and configured and arranged to transmit ultrasonic waves that propagate as plane waves in a direction orthogonal to a surface of the substrate; an acoustic refracting part contacting the ultrasonic transducer, and configured and arranged to refract the ultrasonic waves transmitted from the ultrasonic transducer; an elastically deformable elastic portion contacting the acoustic refracting part; and an ultrasonic reflecting member disposed within the elastic portion, and configured and arranged to reflect the ultrasonic waves. The acoustic refracting part is configured and arranged to refract, toward the ultrasonic reflecting member, the ultrasonic waves transmitted from the ultrasonic transducer.

A method for ultrasonically inspecting components with wavy or uneven surfaces. A multi-element array ultrasonic transducer is operated with a substantial fluid layer, such as water, between the array transducer and the component surface. This fluid layer may be maintained by immersing the component in liquid or by using a captive couplant column between the probe and the component surface. The component is scanned, measuring the two dimensional surface profile using either a mechanical stylus, laser, or ultrasonic technique. Once an accurate surface profile of the component's surface has been obtained, data processing parameters are calculated for processing the ultrasonic signals reflected from the interior of the component that eliminate beam distortion effects and reflector mis-location that would otherwise occur due to the uneven surfaces.

A catamaran type vessel for use in a wastewater facility for servicing submerged air diffusers is disclosed. The vessel has spaced apart pontoon having an A-frame spanning between the upper decks of the pontoon and connecting the pontoons. A hook connected to a winch is secured to a cross header above the space between the pontoons. The hook is lowered into water and lifts an air header, to which the air diffusers are connected. An air diffuser is then pulled on the pontoons and serviced. The vessel is then propelled to a position to service other air diffusers in the pontoon.

The rescue device for the passengers and crew of a ship includes: a container that contains survival equipment; a system that is intended for stowing said container relative to the deck of the ship and contains at least one strap and a system for multimodally attaching and releasing said container; an airbag-type inflatable balloon set up between a structure, secured to the deck, and said container, said structure defining a passage for the passengers when needed; and a means for releasing the airbag set up on the wheelhouse of said ship. The frame-shaped structure is formed of: two side posts; a lower cradle, on which said container rests; an upper crosspiece; and a plate set up inside the ship and acting as a counterbearing for the airbag when said container is ejected.

A jet boat including a hull including a keel extending in a fore and aft direction of the jet boat, at least one jet propulsion nozzle mounted to a rear of the hull, and an articulating keel attached at the rear of the hull, the articulating keel arranged to pivot about a pivot axis extending vertically or substantially vertically. A bottom surface of the articulating keel does not extend below a bottom surface of the keel when the articulating keel is parallel or substantially parallel to the fore and aft direction of the jet boat.

A boat protection device includes a boat fender having a cushion, a first attachment element and a second attachment element. The first attachment element has a first keyhole aperture. The first keyhole aperture has a first slot and a first passage contiguous with the first slot. The second attachment element has a second keyhole aperture. The second keyhole aperture has a second slot and a second passage contiguous with the second slot.

An equipment complex for deploying and recovering marine geophysical seismic or electric-survey bottom stations is mounted on a ship. The complex includes—a powered capstan, —rotatable turntables and rolls, —load-bearing units connected to the bottom stations by various fasten means and capable of winding onto the capstan and turntables, a work platform supporting a bottom station placed thereon, —an indicator for registration of the bottom stations' coordinates, mounted on the platform, —a limit switch mounted on the platform, switching ON when the bottom station is placed on the work platform, and OFF when it's removed therefrom providing for operation of the indicator. The complex may include floating buoys, damping loads, and halyards for deploying the stations. Methods for deploying and recovering the bottom stations using the equipment complex are described. Some recovering methods contemplate winding the load-bearing units onto the capstan, while switching the turntables for each subsequent load-bearing unit.

Disclosed is a bicycle for water and land including: a first floating means, which is provided on and rotates with a front wheel frame that rotates in conjunction with a handlebar, for unfolding on both sides by means of buoyancy to buoy the front wheel frame when entering water; a second floating means, which is provided on a rear wheel frame, for unfolding on both sides by means of buoyancy to buoy the rear wheel frame when entering water; and propellers, which are provided on a plurality of spokes that are installed on the rear wheel frame so that the surfaces face the direction in which the rear wheel rotates, for generating propelling force in water.