108 results about "Nuts and bolts" patented technology

The present application relates to the technical field of fastener, in particular to a nut assembly for preventing loosening and unfastening and a packaging method thereof, the nut assembly is composed of a bolt, a nut and a protection structure, the protection structure includes a protection body with a protection cavity, a guide, an elastic support and an elastic end piece; the elastic support is arranged at one end of the protection cavity; the elastic end piece is detachable at the other end of the protection cavity; the elastic end piece, the guide, the nut, the bolt and the elastic support are distributed along the protection body in the axial direction, and the elastic support and the elastic end piece have a first elastic body and a second elastic body respectively; when the elastic end piece is pressed, the second elastic body supplies air to the nut and cleans it through the guide; when the elastic support is pressed, the bolt is exposed from the cavity opening of the protection cavity, when the elastic support recovers, the bolt is retracted into the protection cavity and wrapped by the first elastic body, the present application completes the cleaning of the nut and the bolt while packaging the beads, reduces the production process flow and ensures the production capacity.

This utility model belongs to the field of pre-embedded bolt anti-loosening technology, and discloses a pre-embedded bolt anti-loosening structure for metal products. It includes a nut rotatably mounted on the lower outer side of the bolt body, grooves on both sides of the nut, a cotter pin fitted inside the grooves and inserted into the bolt body, a locking washer fixed to the upper surface of the nut, and a shape memory alloy spring washer fixed to the lower surface of the nut. Through the cotter pin, shape memory alloy spring washer, and locking washer, the cotter pin prevents relative rotation of the bolt, nut, and other connecting parts under vibration or external force, ensuring a stable and safe connection. The shape memory alloy spring washer can increase the pressure at the connection point, reduce contact resistance, and suppress heat generation by deforming under temperature changes and other environmental conditions. It can also absorb some energy to reduce vibration amplitude and ensure connection stability. The locking washer restricts the rotation of the nut and bolt.

The utility model discloses a kind of grab teeth sleeve, including sleeve body, the top of sleeve body is provided with circular groove, the bottom of sleeve body is provided with hexagonal hole, the inside of circular groove is provided with ring groove, the inside of ring groove is above inherent fixed gear ring, the inside of fixed gear ring is engaged with and connected with mobile gear ring, the inside of mobile gear ring is fixed with hexagonal ring.Nut is placed in the inside of hexagonal hole, bolt passes through sleeve body and grab tooth and nut is screwed, using hexagonal wrench, insert in the outside of bolt, rotate hexagonal wrench to make bolt and nut tighten, remove hexagonal wrench, using tool is inserted into the inside of rotating hole, rotate tool, make mobile gear ring and fixed gear ring correspond, hexagonal ring and bolt correspond, if bolt and hexagonal ring do not correspond, the angle of bolt is fine-tuned, so that it corresponds, such that fixed magnetic ring and mobile magnetic ring repel each other, hexagonal ring and mobile gear ring move up, mobile gear ring and fixed gear ring engage connection, so it can limit the rotation of nut and bolt.

The utility model provides a kind of rust-proof leakage-preventing bolt fastener.The rust-proof leakage-preventing bolt fastener includes device main body, the device main body includes anti-loosening assembly, nut and bolt, the anti-loosening assembly includes the vertical rod set on bolt, the vertical rod is provided with pressing rod, the vertical rod bottom is equipped with fixed block, the pressing rod bottom is equipped with inverted taper block, the vertical rod is equipped with sliding slot, the vertical rod is fixedly installed with fixed plate in it, the fixed plate is provided with push rod, the one end of push rod is equipped with vertical plate, the second elastic member that can assist vertical plate to reset is set around on the push rod, the nut is equipped with vertical groove in it, the vertical groove is provided with limiting plate in it, the vertical groove is provided with shaft piece for connecting nut and limiting plate in it.The rust-proof leakage-preventing bolt fastener provided by the utility model has the effect of improving use safety.

The application relates to a fixing structure of a small unmanned aerial vehicle nest platform threading pipe and a wire protection frame, and relates to the field of small unmanned aerial vehicle nest platform threading pipe fixing devices. The fixing structure of the small unmanned aerial vehicle nest platform threading pipe comprises at least two groups of fixing components used cooperatively, each group of fixing components comprises two fixing clamps, a plurality of nuts and bolts, a fixing seat and a second clamp. Through the special mechanical structure among the fixing clamps, the nuts, the bolts, the fixing seat and the second clamp, two threading pipes can be stably fixed on one side of a platform stand column through the two fixing clamps at the same time. Compared with the traditional fixing by a fixing belt, the fixing effect of the two threading pipes is better and more reliable through the fixing mode of the bolt fastening. Moreover, as the fixing clamps have preset spaces for the threading pipes to enter, the installation operation of the threading pipes becomes simpler, and the problem of poor fixing effect of the traditional threading pipe fixing equipment when fixing the threading pipes is solved.

The self-adaptive workpiece positioning intelligent clamp comprises an adjustable mechanism, a fixed wrench opening is formed in the bottom of the adjustable mechanism, a convenient assembling mechanism is arranged at the top of the adjustable mechanism, a supporting rod is fixedly installed at the top of a bottom plate, and a limiting sliding groove is formed in the right side of the supporting rod; a telescopic rod is slidably connected to the right side of the supporting rod, and a connecting plate is fixedly mounted at the top of the telescopic rod. According to the self-adaptive workpiece positioning intelligent clamp based on visual identification, a plug board of the convenient assembling mechanism is in plug-in fit with a plug seat, a control piece is rotated to drive a threaded rod to be screwed into a threaded hole in the bottom of the plug board, a ratchet wrench opening can be rapidly disassembled, assembled and replaced, nuts and bolts of different specifications are adapted, and replacement of abrasion faults is facilitated; a threaded shaft of the adjustable mechanism rotates to drive a telescopic rod to ascend and descend along a limiting sliding groove to adjust the length, a rotating shaft drives a clamping piece and a fixing plate to rotate to adjust the angle, and adaptability and working efficiency are improved.

This utility model discloses a press-fit blind hole nut structure, belonging to the field of press-fit nut technology. It includes a first retainer and a second retainer, a nut component, and a fixing bolt. The fixing bolt is installed at the inner center of the nut component. The nut component includes a toothed sleeve and a nut sleeve. The toothed sleeve is fixedly installed on the upper outer surface of the nut sleeve. A toothed portion for riveting metal plates is provided at the center of the upper outer surface of the toothed sleeve. The toothed portion has an overall toothed ring structure. The fixing bolt and the toothed sleeve, as well as the fixing bolt and the nut sleeve, are all connected by threads. Several sets of teeth are distributed in a ring on the outer surface of the toothed portion, with one end of each tooth having a pointed shape. This provides a press-fit rotation limiting structure, preventing synchronous rotation of the nut during subsequent bolt installation after it is connected to the sheet metal material. This allows the nut and bolt to be tightened to the maximum extent, improving their performance.

The utility model belongs to the technical field of steel members, and particularly relates to a multidirectional force transmission steel member node strengthening structure which comprises a first steel member body, a connecting frame is arranged at the top of the first steel member body, first connecting holes are formed in the periphery of the bottom of the connecting frame, and third steel member bodies are connected to the two ends of the inner wall of the connecting frame in a clamped mode. And the bottom of the third steel member body is in threaded connection with a bolt. Third steel member bodies are placed on the two sides of the inner wall of the connecting frame, the connecting frame and the third steel member bodies are connected and installed through second nuts and bolts, operation is easy, installation convenience is improved, and the multidirectionality of equipment connection is improved; and the first steel member body and the connecting plate are connected through the second screw and the third nut, the lower portion of the connecting plate is supported through the supporting plate, the connecting stability of the first steel member body and the second steel member body is improved, and the strength of the steel structure joint is improved.

The utility model discloses an anti-loosing fixing structure of a molybdenum lifting grab bolt, and relates to the technical field of mechanical connection and fastening, the anti-loosing fixing structure comprises a bolt, the outer wall of the top of the bolt is fixedly connected with a tooth-shaped gasket, the outer wall of the bolt is provided with an anti-loosing mechanism, and the anti-loosing mechanism comprises a gasket. At the moment, the fixing shaft can drive the sliding plate to continuously slide in a sliding groove formed in the second gasket, when the sliding plate slides to a certain distance, the second gasket makes contact with the spring and continuously extrudes the spring, when the spring is extruded, elastic deformation is generated, and continuous elastic pre-tightening force is applied between the nut and the connected piece. The pre-tightening force enables the friction force between the nut and the bolt to be increased, the nut is prevented from rotating under the action of vibration or other external force, the anti-loosening effect is achieved, it is guaranteed that the molybdenum lifting claw and other components are connected in a fastened state all the time, and therefore normal operation of the whole device is guaranteed.

The utility model belongs to the technical field of fastening equipment, and particularly relates to an anti-loose bolt assembly of a fan tower, which comprises a bolt, a nut, a lower sleeve, a friction structure and an upper sleeve which are matched for use, the bolt penetrates from the lower end of a bolt hole in the fan tower, the nut is screwed and fixed from the upper end, the lower sleeve is sleeved on the nut, and the upper sleeve is buckled from the upper part of the bolt tail. The lower sleeve and the upper sleeve are installed respectively, so that the nut and the bolt tail at different screwing positions can be matched, operation is easy, installation is convenient, relative rotation between the lower sleeve and the upper sleeve is limited through the friction structure, and good fastening and loosening effects are achieved. A flange protruding out of the outer edge is arranged at the upper end of the friction block, the upper sleeve comprises an annular groove and a first chamfer, the process that the upper sleeve is inserted into the lower sleeve is smoother through cooperation of the flange, the first chamfer and the annular groove, and the relative position of the upper sleeve and the lower sleeve can be limited.

The invention discloses a combined electric meter cabinet, and relates to the field of electric meter cabinet application, the combined electric meter cabinet comprises an electric meter box, two groups of vertical rods are symmetrically arranged in the electric meter box, the side surfaces of the vertical rods are provided with first limiting grooves and racks, the outer parts of the two groups of vertical rods are movably provided with adjusting mechanisms, and a cross rod is movably installed between the two groups of adjusting mechanisms; the adjusting mechanism is composed of a clamping assembly and an adjusting assembly. The adjusting mechanisms are arranged between the vertical rods and the transverse rods for installation, so that the multiple sets of transverse rods are located on the side faces of the vertical rods, the height can be adjusted, and compared with the installation mode that the transverse rods and the vertical rods are fixed through nuts and bolts, the transverse rods can conduct secondary height calibration, and the installation efficiency is improved. Therefore, a worker can carry out secondary calibration and typesetting according to the sizes of the electrical components, so that the electrical components are arranged in the electric meter box more orderly and reasonably.

This utility model relates to the field of construction and discloses an adjustable connecting corner bracket construction tool, including a corner bracket first component, a corner bracket second component, and a connecting bolt assembly. The corner bracket second component has a U-shaped groove structure, and its main board has bolt adjustment holes. The corner bracket first component can be embedded into the U-shaped groove of the corner bracket second component, and its main board has corresponding bolt adjustment holes. The connecting bolt assembly includes a nut and a bolt, and the bolt passes through the bolt adjustment holes of the corner bracket first component and the corner bracket second component in sequence, and is fastened together by the nut and bolt. In this utility model, by changing the relative position of the bolt and the bolt adjustment hole, the corner bracket second component can achieve short-distance extension and retraction adjustment, while the corner bracket first component can both extend and retract short distances and rotate left and right. The combination of the two components changes the relative position relationship, allowing the installed stone to form a multi-faceted irregular shape effect, meeting the adjustment needs of irregular stone installation and improving construction flexibility.

1. The name of the design product: screwdriver (CS20). 2. The use of the design product: used for loosening and tightening various types and specifications of screws, nuts and bolts. 3. The design points of the design product: in shape. 4. The picture or photo that best indicates the design points: perspective view.

The utility model discloses an aluminum bar electric connection structure of a new energy automobile, which comprises an injection molding installation support, an installation nut and a bolt, the injection molding installation support comprises an installation groove, a limiting groove arranged at the lower end of the installation groove and an installation hole communicated with the installation groove and the limiting groove, and the diameter of the installation hole is larger than that of the limiting groove. The installation nut and the injection molding installation support are integrally connected in an injection molding mode, the installation nut comprises a supporting part at least partially embedded in the installation hole and an installation part embedded in the limiting groove, the upper end of the supporting part comprises a supporting face, the bolt comprises a limiting part and a threaded part, the lower end of the limiting part comprises a limiting face, and the threaded part sequentially penetrates through the aluminum bars. The limiting surface and the supporting surface cooperate together to continuously apply limiting force in the axial direction to the aluminum bars, and the lower end of the threaded part is embedded into the mounting part and is in threaded connection with the mounting part. According to the utility model, through the combined design of the injection molding mounting bracket, the mounting nut and the bolt, the tight connection between the aluminum bars is realized.

The utility model discloses an anti-loosing parallel hanging plate which comprises a first hanging plate and a second hanging plate, the first hanging plate is provided with a bolt and penetrates through the second hanging plate, the bolt is sequentially provided with a flat gasket and a spring washer, a screw rod of the bolt is in threaded connection with a nut, so that the flat gasket is tightly pressed on the second hanging plate, and the spring washer is arranged on the second hanging plate. The second hanging plate is provided with a protruding connecting part, the connecting part is provided with a cavity for containing a nut, the cavity abuts against the outer wall of the nut, a locking cap is arranged on the outer wall of the connecting part, a threaded part is arranged in the locking cap, and the locking cap is in threaded connection with the bolt. Reversion of the nut due to external force vibration is avoided through the cavity; the friction force between the nut and the bolt is increased through the spring washer, meanwhile, the locking force between the bolt and the second hanging plate is improved through the threaded part, the bolt is prevented from reversing due to external force vibration, and the product has the advantages of improving the locking force and preventing looseness.

The utility model provides a tool for pipe plugging and pressure testing, which comprises an end cover, a boss, a conical sliding block, a sealing ring, a bottom plate, a water inlet pipe, a nut and a bolt, the end cover, the boss and the bottom plate are connected through the nut and the bolt, and the bolt penetrates through the lower end of the end cover and the lower end of the boss from top to bottom and is connected with the bottom plate. The nut is connected to the upper end of the bolt and is in contact connection with the upper surface of the end cover; the lower portion of the end cover is clamped to a pipe opening, the boss and the bottom plate are arranged in the pipe, a space is formed between the outer wall of the boss and the inner wall of the pipe, the conical sliding block is arranged in the space, and a sealing ring is arranged between the outer edge of the lower portion of the boss and the bottom plate and is in contact connection with the inner wall of the pipe. The water inlet pipe penetrates through the end cover and the lower end of the boss from top to bottom to be connected with the bottom plate, the water inlet pipe penetrates out of the upper end of the end cover to be connected with the water inlet, and a through hole structure III is arranged in the water inlet pipe and communicated with the interior of the pipe. According to the plug, the sealing performance after assembly can be guaranteed, and the problems of an existing plug made of steel are solved.

1. The name of the design product: electric screwdriver (CS16). 2. The use of the design product: the design product is used for tightening various types and specifications of screws, nuts and bolts. 3. The design points of the design product: in shape. 4. The picture or photo that best indicates the design points: perspective view.

The article relating to the present design is a gauge for measuring the size of nuts and bolts.

This invention provides wooden member connecting members, wooden seismic-resistant members, and high nuts and lag screw bolts that constitute them, which are less prone to buckling than conventional materials. [Solution] The device comprises a bolt 1 that engages with a gusset plate 9, a lag screw bolt 5 fixed to the bottom 4a side of the pilot hole 4 and having a hollow portion 55 that opens to the rear end 54 of the screw, a rod 6 having first threaded portions S1 and second threaded portions S2 at both ends 6a and 6b that screw into a high nut 7 and the lag screw bolt 5, and an expandable portion E extending between them, and a high nut 7 that screws into the bolt 1 and the rod 6, all arranged coaxially Q with the pilot hole 4. The high nut 7 or the lag screw bolt 5 has a non-threaded portion N within the hollow portions 71, 55 that allows displacement of the expandable portion E in the axial direction Z. The high nut 7 has a length L longer than the maximum assumed extension length MAX of the expandable portion E inserted into the pilot hole 4, and its displacement direction is constrained to the axial direction Z by the inner surface 4d of the pilot hole 4.

The utility model belongs to the technical field of fastener, and relates to a new bolt, including bolt main part, the hexagon nut is fixed with outside top of bolt main part, the hexagon nut and bolt main part are integrative cast and form, automatic glue injection subassembly, its one side is located in the outside of bolt main part, the inside of automatic glue injection subassembly includes anti -skidding mechanism and shock -resistant mechanism, and anti -skidding mechanism and shock -resistant mechanism cooperate and use, the utility model discloses through the use of liquid storage sac, flow guide groove, gasket, makes in the bolt main part is used to connect mechanical parts, through the filling of liquid storage sac to flow guide groove, makes the part connection more closely and firmly, reduces the bolt main body in the process of using, appears because high -frequency vibration and separates the situation, reduces the possibility of production accident because bolt main body loosens, simultaneously when using bolt main body, need not extraly add gasket and anaerobic glue to bolt main body outside, further improves work efficiency.

The utility model discloses a light assembly type prefabricated wallboard with a connecting structure, which belongs to the technical field of building material equipment and comprises a plate, a bolt is arranged on the side of the plate, a nut is mounted on the bolt in a threaded manner, conical pressing sleeves are symmetrically arranged between the nut and the bolt, the bolt is sleeved with the conical pressing sleeves in a sliding manner, and the connecting structure is arranged between the conical pressing sleeves and the plate. The conical pressing sleeve is sleeved on the side part of the plate, and one end of the plate is butted and matched with the other end of the plate. An elastic frame is arranged on one side of the plate, and the root of the elastic frame is fixedly connected with the plate. Each plate comprises a plate body, after the two plates are aligned, one conical pressing sleeve is arranged on the bolt in a sleeving mode, then the bolt penetrates through the position between the two plates, then the other conical pressing sleeve is arranged on the bolt in a sleeving mode, the nut is screwed on the bolt till the nut is screwed, the nut and the bolt are used for clamping the conical pressing sleeves, and the conical pressing sleeves are clamped through the bolt. And the two plates are tightly sleeved with the conical pressing sleeve, so that the two plates are automatically aligned and fixed, and the practicability is improved.

This utility model provides a turbine flow meter housing and a protective structure for the housing, including a flange disposed at the end of the pipeline and the housing; a plurality of bolts disposed in the mounting holes of the flange; and a protective structure sleeved on the nuts and / or bolts, including a bottom gasket disposed on the mounting side of the nuts and / or bolts, with multiple sealing portions circling from the center outward on the side of the bottom gasket facing the mounting side. This utility model, by sleeved on the end faces of the nuts and bolts, allows the bottom gasket to be pressed between the end faces of the flange and the nuts and bolts, forming multiple sealing portions that enhance the compressive force between the flange and the end faces of the nuts and bolts, improve the sealing performance of the nut and bolt positions, prevent corrosive liquids from entering the bolt connection surface from gaps, effectively solve the problem of bolt corrosion, and thus stabilize the fastening force between the housing and the pipeline.

The utility model discloses a nut anti -loose device for railway turnout, including steel rail packing ring, installation component, bolt, nut and anti -loose component, steel rail packing ring is used for installing in the steel rail waist, and installation component is connected with steel rail packing ring, and bolt is used for being in order to be provided in steel rail, steel rail packing ring and installation component, and the free end of nut and bolt is screwed, and anti -loose component is detachably connected with installation component, and anti -loose component is set up with the anti -loose cavity of the outer wall of nut for setting up in the nut outer for limiting the rotation of nut in profile. The scheme adopts mechanical type anti -loose device, and the installation dismounting operation is convenient, and relative to prior art, while ensuring that the nut assembly is convenient, the anti -loose effect of nut is good, and the practicality is strong, is suitable for extensive promotion and application.

1. The name of the design product: the anti-scratching sleeve body of the open-end wrench. 2. The use of the design product: the product is used to be sleeved on the head of the open-end wrench to prevent the user from scratching the fasteners such as nuts and bolts when using the open-end wrench. 3. The design points of the design product: in shape. 4. The picture or photo best indicating the design points: the design 1 perspective view. 5. Design 1 is designated as the basic design. 6. The design is a partial design, and the dotted part is not protected.

The utility model discloses a forward and reverse rotation automatic reset mechanism which comprises a gear box, a gear B, a gear C and a gear E, a gearbox cover is arranged at the bottom of the gearbox, and a gear A is arranged on the surface of the gearbox cover; the gear B is meshed with the surface of the gear A; by means of a limiting mechanism composed of the pulling plate, the positioning column, the spring and the indexing pin, forward and reverse rotation of the lengthened wrench can be conveniently controlled, the rotation direction of the lengthened wrench can be rapidly switched, complex disassembly or adjustment operation is not needed, and work efficiency is greatly improved; by means of the design of the lengthened wrench, the wrench can be conveniently and rapidly connected with nuts and bolts of various specifications through the cooperation of the hexagonal screw opening A in the bottom, the operation requirements of connecting pieces of different sizes are met, and the application range of the mechanism is widened. Meanwhile, through the arrangement of an upper bearing, a lower bearing and a bearing C and the synergistic effect of a fixing block A, a fixing plate B, an anti-shaking arm and other components, the precision and reliability of gear transmission are guaranteed, and the service life of the mechanism is prolonged.

The utility model relates to the technical field of nuts and bolts, and discloses a special-shaped nut with a self-locking anti-loosening structure, which comprises a screw rod, a stud is fixedly connected to the top end of the screw rod, a first nut is detachably connected to the outer wall of the screw rod through threads, a threaded sleeve is detachably connected to the outer wall of the stud through threads, and a connecting plate is rotatably connected to the outer wall of the threaded sleeve. The connecting plate is connected with the first nut through the fixing assembly, the screw rod is provided with clockwise threads, and the stud is provided with anticlockwise threads. According to the utility model, the first nut is clockwise rotated to the screw rod, and then the sleeve is anticlockwise rotated to the stud, so that the thread bushing drives the connecting plate and the first nut to abut against each other and be tightened, and meanwhile, the fixing block on the connecting plate is fixed in the slot on the first nut; the first nut and the threaded sleeve are mechanically interlocked and connected together, so that the first nut and the threaded sleeve are prevented from loosening, and the stability of the connecting piece is improved.

The utility model discloses a pod body structure, which relates to the technical field of airborne pods of airplanes, and comprises a pod main cylinder body, the pod main cylinder body comprises two arc-shaped main beams which are arranged in parallel up and down, and the corresponding sides of the two main beams are fixedly connected through an end frame; at least two bulkheads are arranged between the two main beams, and each bulkhead is fixedly connected with the two main beams; the bulkheads divide the pod main cylinder body into a plurality of cabins; opening frames are arranged on the two sides of the pod main cylinder, and the upper ends and the lower ends of the two opening frames are fixedly connected with the two main beams respectively. According to the pod structure provided by the utility model, the structures are connected by adopting supporting plate nuts and bolts for mechanism assembly, so that assembly and subsequent product installation and maintenance are facilitated. The overall structural rigidity is good; the number of rivets is reduced, and the skin is not prone to instability; the stress concentration dangerous section is reduced.

One object of the present invention is to provide a method for estimating the bolt axial force and a system for estimating the bolt axial force that are capable of evaluating a change in the elongation of a bolt with high accuracy. A method for estimating the bolt axial force of the present invention is a method for estimating the bolt axial force for a fastening element in which a body to be fastened is fastened by a nut and a bolt, wherein the nut has a plurality of strain gauges arranged in a center in the axial direction or on a side that is closer to the body to be fastened than the center, wherein the method for estimating the bolt axial force comprises: a measuring step of measuring an amount of strain of the nut by the strain gauges which are attached to three outer surfaces of a nut outer surface at intervals of 120 degrees and at equal distances from the body to be fastened and a nut contact surface; a calculation step of calculating an average value of the amount of strain from the amount of strain;and an estimation step of estimating a bolt axial force from the mean value of the strain magnitude and a pre-prepared relationship between strain and bolt axial force.

The application provides a kind of semi-automatic thread detection machine, it is related to thread detection technical field, including workbench and drive box, drive mechanism is equipped in drive box;Thread detection piece is detachably connected with the output end of drive mechanism;L-shaped support frame is fixed on the working surface of workbench;Detection pad is slidably installed on L-shaped support frame by support assembly, and installation groove for limiting the workpiece to be detected is provided on detection pad;Detection element is fixedly installed on L-shaped support frame or workbench, for detecting the moving position of detection pad;Controller is electrically connected with drive mechanism and detection element respectively, for controlling drive mechanism forward rotation or reverse rotation according to detection element signal.The drive mechanism drives the thread detection piece to rotate, and the inner thread detection head or the outer thread detection head and the workpiece positioning block can be quickly replaced, which is suitable for thread quality detection of nuts and bolts, has high detection efficiency and reduces labor and equipment costs.