45results about How to "Ease of engineering" patented technology

The invention discloses a single-degree-of-freedom overconstrained shear-type deployable unit and space deployable mechanisms composed of the same. The single-degree-of-freedom overconstrained shear-type deployable unit comprises eight disc chucks, four sets of shear fork folding rods and eight sets of folding connecting rods; one set of the folding connecting rods limit the deployable degree of the basic deployable units by depending on the length of the connecting rods, the other seven sets of the folding connecting rods are all overconstrained connecting rods, and the overconstrained connecting rods can effectively improve the rigidity of the basic deployable units. Accordingly, the basic deployable units can be sequentially arranged in order, every two adjacent deployable units can form the first space deployable mechanism and the second space deployable mechanism by sharing four of the disc chucks and one set of the shear fork folding rods, and the length of the first space deployable mechanism and the size of the second space deployable mechanism can be changed by changing the quantity of the basic deployable units. The single-degree-of-freedom overconstrained shear-type deployable unit is simple in structure, has the high structural symmetry and is suitable for constructing an extendable space mast, a solar battery array support and a satellite plane reflecting antenna.

The invention relates to a scissors type hexagonal-prism-shaped extensible unit and a space extensible mechanism formed by the same. The scissors type hexagonal-prism-shaped extensible unit being a single-freedom-degree over-constrained hexagonal-prism-shaped basic extensible unit comprises twelve floral discs, six groups of scissors type folding rods, and twelve groups of folding connecting rods. One group of folding connecting rods limits the extending degree of the basic extensible unit based on the connecting rod lengths and the rest of eleven groups of folding connecting rods are over-constrained folding connecting rod, so that the rigidity of the basic extensible unit is improved effectively. Multiple basic extensible unit are arranged closely and the adjacent basic extensible units can form a space extensible mechanism by sharing four floral discs, one group of scissors type folding rods and two groups of folding connecting rods; and the size of the pace extensible mechanism can be changed by changing the number of the space extensible units. The provided scissors type hexagonal-prism-shaped extensible unit has high structural symmetry; and different large-dimension space extensible mechanisms can be formed based on assembling of multiple extensible units. Therefore, the scissors type hexagonal-prism-shaped extensible unit and the space extensible mechanism are suitable for constructing a space solar battery array bracket and a satellite planar reflecting antenna.

The present invention provides a complete scissor-like double-layer annular truss extendible antenna mechanism. The mechanism comprises an inner layer annular truss component, an outer layer annular truss component and N inner and outer layer connection truss components; the inner layer annular truss component and the outer layer annular truss component both include N extending units; two common flower discs are connected between adjacent extending units; the inner and outer layer connection truss components are concentrically arranged; two upper and lower flower discs at each side of the inner layer extending units are connected with the corresponding two upper and lower outer layer flower discs at each side of the outer side layer extending units respectively through one inner and outer layer connection truss component to form a double-layer annular truss; and the distance between the length of the rod pieces at the same position of the inner and outer layer extending units and a flower disc rotation secondary axis and a center line satisfies a special proportional relation, and the ratio of the inner layer and the outer layer is (1-sin(180 / N)) / (1+sin(180 / N)). The complete scissor-like double-layer annular truss extendible antenna mechanism is high in rigidity, simple in structure and high in reliability, and can be applicable to a communication satellite, a space station and a space probe.

The invention discloses a 3R-3RSR single-degree-of-freedom tetrahedron expandable unit, which comprises a top face plate, three swing rods with equal lengths, six connecting rods, nine rotation pairs and three ball pairs, wherein the upper ends of the three swing rods are connected with the top face plate through three coplanar rotation pairs; the axis of each rotation pair is vertical to a plane which is determined by an intersection point of the upper ends of the three swing rods, a triangular circumcenter of the tetrahedron unit and the lower end point of the corresponding swing rod; the lower end of each swing rod is respectively connected with two folding rods through two rotation pairs; each folding rod comprises two connecting rods with equal lengths and one ball pair; the unit is in a completely expanded state; the axes of the rotation pairs at two ends of each folding rod are parallel to each other and are vertical to the connected line of the centers of two rotation pairs; and the unit can be folded or expanded by driving any rotation pair. The 3R-3RSR single-degree-of-freedom tetrahedron expandable unit has the advantages of being single in degree of freedom, few in hinges, simple in structure, small in folding volume and the like, and is suitable for a large-caliber truss-type expandable antenna.

The invention discloses a control method for a single-phase grid-connected inverter and a control parameter obtaining method therefor. The control method comprises the steps of collecting a power grid voltage value Ug, and inputting a phase-locked loop algorithm to obtain a phase angle <theta> of the power grid voltage; setting an amplitude value Im of a power grid reference current, and obtaining the power grid reference current Iref; enabling Iref and Ig to be subtracted obtain an error E, and enabling the obtained error E to pass through a proportional resonant controller and a harmonic compensation controller separately; enabling the output Upr of the proportional resonant controller to be added with the output Uhc of the harmonic compensation controller to obtain a sum Uab, and carrying out amplitude limiting on the obtained sum Uab to obtain a capacitive current reference value Icref of the filter; enabling the Ic and a feedback coefficient Kc to be multiplied to obtain a capacitive current feedback signal Ikc of the filter; enabling the difference value between the Ic and Ikc to be multiplied by a gain coefficient Kpwm of a PWM to form a modulation signal of a single-phase full-bridge inversion unit; and generating the driving pulse of the single-phase full-bridge inversion unit by the modulation signal. The control method is simple and feasible and capable of effectively restraining low-order harmonics.

The invention discloses a preparation method of polyvinylidene fluoride modified film, which has the technique comprising the following steps of: 1. designing the following components of casting film liquid by weight percent: 14-18% of PVDF, 2-6% of PAN, 4-12% of pore-forming agent and 68-76% of solvent, wherein the pore-forming agent is soluble polymer including polyethylene glycol, and the solvent is good solvent of PVDF and PAN and comprises dimethyl acetyl amide, dimethyl formamide or dimethyl sulfoxide; stirring the components in water bath at 60-70 DEG C for 3-4h, carrying out vacuum defoamation, and obtaining the casting film liquid; 2. manufacturing the casting film liquid into a flat-plat film at the room temperature, then immediately dipping into coagulating bath, maintaining for 24h and curing for molding; and 3. putting the flat-plat film into sodium hydroxide solution with the mass concentration of 8-12%, and treating at 50-60 DEG C for 1-2h; or putting the flat-plat film into sulfuric acid solution with the mass concentration of 40-50%, and treating at 80-100 DEG C for 3-4h; and then, washing the film until neutrality, and obtaining the polyvinylidene fluoride modified film.

Belonging to the technical field of preparation of aluminum based composite materials, the invention especially relates to a laser weldable aluminum based composite material and a preparation method thereof. The method provided by the invention includes: mixing silicon powder and aluminum powder according to a proportion in a mixing tank uniformly to obtain a powder mixture, and subjecting the powder mixture to cold isostatic pressing, high temperature and high vacuum degassing, and hot isostatic pressing densification treatment, thus obtaining the 100% compact, and internally imporous Si / Al composite billet. The method provided by the invention has the advantages of simple and stable process and low cost, and is one of the preferred methods for preparation of preparation of high reliability and stable quality packaging materials. The Si / Al composite material prepared by the method not only has the characteristics of light weight, low expansion and high thermal conductivity, but also has high and stable mechanical properties, especially has the characteristics of good laser welding technological properties and high air tightness, thus being an advanced aluminum based composite material with an integrated functional structure. And the material can be applied as a hermetic encapsulation shell for microelectronic devices and photoelectric devices.

A 9RR-12URU-3URU symmetrical extendable basic unit mechanism includes 10 face plates, 9 swing rods with equal lengths, 6 folded rods I, 6 folded rods II, 3 folded rods III, 33 revolute pairs (R) and 30 Hooke joints (U). Six of the face plates at the periphery in the upper layer are connected with the central face plate through the folded rods I and are connected with each other through the folded rods II. Three of the face plates in the lower layer are connected to each other through the folded rods III. Each of the folded rods is formed by connecting two connecting rods of equal lengths through one of the revolute pairs, and two ends of the folded rod are connected with the face plates through the Hooke joints. Each of the face plates in the lower layer is connected with the central face plate and two of the face plates at the periphery in the upper layer through three of the swing rods. Two ends of each swing rod are connected with the face plates through the revolute pairs. The central face plate and the face plates at the periphery in the upper layer are on the same spherical surface and form a regular hexagon with the face plates at the periphery as vertices. The mechanism is simple in structure, high in rigid, and easy for implementation of engineering manufacture. The mechanism can fold all face plates simultaneously and can adjust the folded face plate attitudes, and has a high folding ratio.

The invention discloses a hybrid scissors-forks type extensible antenna mechanism of a double-layer ring-shaped truss. The hybrid scissors-forks type extensible antenna mechanism mainly comprises an inner-layer ring-shaped truss assembly, an outer-layer ring-shaped truss assembly, a central fixed scissors type connecting assembly and a central movable scissors type connecting assembly, wherein theinner-layer ring-shaped truss assembly comprises n inner-layer folding and stretching units; the outer-layer ring-shaped truss assembly comprises 2n outer-layer folding and stretching units; the central fixed scissors type connecting assembly comprises n fixed scissors type folding and stretching units and n / 2 central movable scissors type folding and stretching units; upper and lower four inner-layer disk chucks at the two sides of the inner-layer folding and stretching units and upper and lower six outer-layer disk chucks of corresponding two outer-layer folding and stretching units definethe double-layer ring-shaped truss mechanism through two central fixed scissors type folding and stretching units and one central movable scissors type folding and stretching unit. The hybrid scissors-forks type extensible antenna mechanism is simple in implementation way, is high in reliability, has the advantages of being flexible in movement and relatively great in folding, and can be applied to a communication satellite, a space station and a space detector.

The invention discloses a high beam and low beam integrated LED headlamp. The high beam and low beam integrated LED headlamp comprises an LED light source, a lens set, a light distributing unit, a movable cut-off light barrier and a collecting lens which are sequentially arranged, wherein the focus of the lens set is on an optical axis of the corresponding LED light source; the light distributing unit and the movable cut-off light barrier are correspondingly positioned at the upper side and the lower side of the optical axis of the LED light source. The high beam and low beam integrated LED headlamp is simple in structure, and low in cost, and meets the demand of a high beam and a low beam.

The invention relates to an over-constrained shear fork-type double-layer annular truss deployable antenna mechanism. The over-constrained shear fork-type double-layer annular truss deployable antenna mechanism comprises an inner-layer annular truss assembly, an outer-layer annular truss assembly and 2N inner and outer-layer connection truss assemblies; the inner-layer annular truss assembly includes N inner-layer folding and unfolding units; adjacent inner-layer folding and unfolding units are connected with each other through two common inner-layer disc chucks, so that the inner-layer annular truss assembly can be formed; the outer-layer annular truss assembly includes N outer-layer folding and unfolding units; adjacent folding and unfolding units are connected with each other through two common outer-layer disc chucks, so that the outer-layer annular truss assembly can be formed; and two inner-layer disc chucks at the upper part and lower part of the same side of each of inner-layer folding and unfolding units are connected with four outer-layer disc chucks of a certain outer-layer folding and unfolding unit through two inner and outer-layer connection truss assemblies, so that the shear fork-type double-layer annular truss deployable antenna mechanism can be formed. The shear fork-type double-layer annular truss deployable antenna mechanism of the invention has good manufacturing process, high rigidity and large folding ratio.

A process for quickly growing the large-diameter monocrystal of potassium dihydrogen phosphate by solution temp lowering method features that the consumptions of potassium chloride and EDTA are respectively 1-5 M% and 0.01-0.02 Wt%, the initial over-saturation is 8 deg.C for maximum, and the temp lowering speed is 0.3-0.5 deg.C per day for initial growing stage and 2 deg.C per day for fast growing stage.

The invention discloses an expandable antenna mechanism of a torsion spring driven shears-fork annular truss. The mechanism comprises N folding and unfolding units with completely same structure, and the adjacent folding and unfolding units are connected by shared upper and lower flower discs to form a polygonal annular truss. Each folding and unfolding unit comprises two shears-fork rods, two groups of torsion spring driving assemblies, four connecting rods and four flower discs. All rotating pair axes on the shears-fork rods and the connecting rods in the same folding and unfolding unit are parallel. The mechanism has the characteristics of high rigidity, flexibility in motion and large folding ratio; and by adopting torsion spring driving, the whole mechanism is fast in unfolding and quick in response, and can be applied to communication satellites, space stations and space detectors.

The invention discloses a scissor-like frame linkage over-constraint double-layer annular truss deployable antenna mechanism which mainly comprises an inner annular truss component, an outer annular truss component and an inner and outer truss connecting component. The inner annular truss component comprises n inner folding and unfolding units, two adjacent inner folding and unfolding units are connected through an upper inner flower disc and a lower inner flower disc which are shared, the outer annular truss component comprises 2n outer folding and unfolding units, two adjacent outer foldingand unfolding units are connected through an upper outer flower disc and a lower outer flower disc which are shared, the inner and outer truss connecting component comprises 2n middle folding and unfolding units, the inner annular truss component and the outer annular truss component are concentrically arranged, and the upper inner flower disc and the lower inner flower disc of each side of each inner folding and unfolding unit are connected with the upper outer flower disc and the lower outer flower disc of each side of the corresponding outer folding and unfolding unit through the middle folding and unfolding units. The antenna mechanism has the advantages of high stiffness and reliability and simple structure and is applied to communication satellites, space stations and space detectors.

The invention relates to a thermal-shock-resistant oxide wave-transparent ceramic material and a preparation method thereof. The ceramic material comprises the following components in percentage by volume: 20-92% of an oxide ceramic matrix with a dielectric constant less than or equal to 10 and 8%-80% of silicon dioxide-coated calcium zirconium phosphate ceramic. The linear expansion coefficient of the material at a room temperature of -1000 DEG C ranges from 0*10<-6> / K to 0.3*10<-6> / K, and the material has excellent thermal shock resistance and good dielectric and mechanical properties. According to the invention, a certain proportion of nano-silica coated calcium zirconium phosphate ceramic particles are introduced into a low-dielectric oxide ceramic material, and the ceramic material with an expansion coefficient close to zero is obtained through air atmosphere high-temperature heat treatment. The method is based on a mature ceramic material preparation method, and is simple to operate, short in period, low in cost, low in process amplification difficulty and easy to realize engineering.

The invention discloses an electromagnetic assisted braking system and a vehicle with the electromagnetic assisted braking system. The electromagnetic assisted braking system comprises an operating device, a control lever and an electromagnetic assisted device, the operating device comprises a braking pedal, and the braking pedal can rotate around a braking pedal rotating axis; the control lever is connected with the braking pedal and used for transferring the braking force of the braking pedal to a braking master cylinder; the electromagnetic assisted device is in linkage with the braking pedal, and thereby when a driver steps on the braking pedal, an electromagnetic assisted force in a same direction as the braking force is applied to the control lever. According to the electromagnetic assisted braking system, an electromagnetic structure is adopted to achieve the assisted force of the braking pedal, the structure is simple, the performance is stable, the cost is low, the maintenanceis convenient, engineering is implemented easily, the electromagnetic action is used to make the driver use less force, thus the braking of the vehicle can be achieved conveniently, and the driving safety is facilitated.

The invention discloses a rainwater abandonment system, which includes a rainwater confluence pipe, a side flow sampling pipe, a sewage pipe, a rainwater abandonment device, a rainwater collection pipe, a rainwater storage tank and a waste flow control box, wherein: the side flow sampling pipe and The rainwater confluence pipe is cross-connected, and its input end is equipped with a water quality analyzer, and the output end is connected to the sewage pipe; the rainwater abandonment device is provided with a water inlet, a water outlet and a sewage outlet, and the water inlet is connected to the output end of the rainwater confluence pipe. The water outlet is connected to the input end of the rainwater collection pipe, the sewage outlet is connected to the input end of the sewage pipe, and the output end of the sewage pipe is provided with a sewage valve; the liquid level gauge is installed in the rainwater storage tank and connected to the output end of the rainwater collection pipe ; The waste flow controller controls the opening and closing of the rainwater waste flow device and the blowdown valve according to the detection results of the water quality analyzer and the liquid level gauge. The invention solves the problem that the initial runoff rainwater and excess rainwater enter water storage equipment or structures, and avoids the potential safety hazards of confluence of rain and sewage and overflow of excess rainwater.

The invention relates to a scissors fork linkage type double-layer circular truss unfoldable antenna mechanism. The scissors fork linkage type double-layer circular truss unfoldable antenna mechanism includes an inner-layer circular truss assembly, an outer-layer circular truss assembly and N inner and outer layer connection truss assemblies; each of the inner-layer circular truss assembly and the outer-layer circular truss assembly includes N folding and unfolding units, wherein adjacent folding and unfolding units are connected through two disk chucks; after being unfolded, each of the inner-layer circular truss assembly and the outer-layer circular truss assembly is a multi-faced circular truss structure; the inner-layer circular truss assembly and the outer-layer circular truss assembly are arranged concentrically; four disk chucks between the inner-layer circular truss assembly and the outer-layer circular truss assembly, which are located in a vertical plane, are connected together through one inner and outer layer connection truss assembly; the structure form and connection mode of the inner-layer folding and unfolding units are similar to the structure form and connection mode of the outer-layer folding and unfolding units; outer-layer rods are longer than inner-layer rods; and the length difference value of the outer-layer rods and the inner-layer rods can be designed according to the specific aperture and folding ratio of the unfoldable antenna. The scissors fork linkage type double-layer circular truss unfoldable antenna mechanism of the invention has the advantages of high rigidity, structural simplicity and high reliability. According to the scissors fork linkage type double-layer circular truss unfoldable antenna mechanism, the expansibility of modules is high, and the number of the modules can be changed randomly according to the requirements of the aperture of the antenna and the sizes of units. The scissors fork linkage type double-layer circular truss unfoldable antenna mechanism can be applied to communication satellites, space stations and space detectors.

The invention provides a comprehensive recycling device and method for asphalt pavement resources, and belongs to the technical field of aggregate and asphalt recycling. The system comprises a storagebin, an ore feeder, a crusher, a belt conveyor, a mill, wet-type screening equipment, a coarse-grained aggregate product conveying belt, a ball mill, coarse-fine grading equipment, a stirring barrel,solid-liquid separation equipment and flotation equipment; and asphalt concrete of an asphalt pavement is fed into the storage bin, the storage bin is connected with the ore feeder, the ore feeder feeds the asphalt concrete into the crusher, a crushed product is fed into the mill through the belt conveyor, obtained ore pulp is screened through the wet-type screening equipment, and an obtained screened material is fed into the ball mill for grinding and flotation. According to the device and the method, comprehensive recycling of coarse-grained aggregate, medium-grained aggregate, fine-grainedaggregate and asphalt concentrate of the asphalt pavement resources can be realized, and recycled asphalt is high in grade and excellent in aggregate performance; and the method is conveniently to realize engineering, water resource saving and environmental protection are realized through washing water closed circulation, and the method has good social, economic and environmental benefits.

The invention discloses interface interlocking / rib reinforced laminated armor aluminum alloy and a preparation method thereof. The laminated armor aluminum alloy is formed by extruding, combining and rolling a back plate, a middle plate and a face plate. The laminated armor aluminum alloy is provided with a spatial interface with interlocked components, and a rib structure is arranged in the rolling direction. The preparation method comprises the following steps that 1) cast ingots on the back plate, the middle plate and the face plate are extruded into a prefabricated blanks with a big-end-up cavity, a prefabricated blank with an n-shaped structure and a prefabricated blank with a big-end-up rib structure correspondingly; 2) surface treatment is carried out on the prefabricated blanks; 3) the face plate, the middle plate and the back plate are extruded and combined; (4) the combined blanks are rolled and combined; and 5) solid solution and aging treatment is conducted. The interface bonding strength is increased through interface interlocking between the laminated armor aluminum alloy components, and interlayer cracking can be prevented. The rib structure improves the strength, rigidity and elasticity resistance of the plates. The preparation method is convenient to operate and beneficial to industrial production.

The invention provides a construction method of a large-diameter steel-concrete combined cylindrical structure, which comprises the following steps: manufacturing a steel cylinder body and dowel bars: manufacturing the steel cylinder body and a plurality of dowel bars, and forming a notch in the lower end part of each dowel bar; the dowel bars and the steel cylinder are installed, specifically, the dowel bars are vertically inserted into the upper end of the cylinder wall of the steel cylinder at intervals through the notches to be fixed; the supporting structure comprises a plurality of transversely-arranged supporting rods, one end of each supporting rod is connected with one dowel bar, and the other ends of the supporting rods intersect and are fixed on the central axis of the steel cylinder; manufacturing and mounting of an annular driver: fixedly connecting the annular driver with the upper end part of the dowel bar; vibration sinking construction is conducted, specifically, a vibration sinking tool is installed for vibration sinking, and after vibration sinking construction is completed, the annular replacement hitting structure and the supporting structure are dismantled; prefabricating the concrete cylinder; and mounting the concrete cylinder. According to the construction method, the construction cost can be effectively reduced, engineering manufacturing is easy, and the obtained cylindrical structure is high in durability.

The invention belongs to the technical field of short-pulse laser and particularly relates to a laser capable of directly generating two paths of coherent light. An existing multi-beam laser photoetching device has the defects of excessive devices, low light energy utilization rate, non-uniform interference fringe light intensity distribution and the like. The invention provides the laser capableof directly generating two paths of coherent light. The laser comprises a first laser oscillation assembly, an electro-optic Q-switching assembly and a second laser oscillation assembly which are arranged in sequence, the first laser oscillation assembly comprises a first Dammann transmission grating, a first laser crystal excitation component and a first Dammann reflection grating which are arranged in sequence; the second laser oscillation assembly comprises a second Dammann reflection grating, a second laser crystal excitation component and a second Dammann transmission grating; the first laser crystal excitation component comprises a first pump light source and a first laser crystal, and the second laser crystal excitation component comprises a second pump light source and a second laser crystal. The double-path light interference effect is good, the working efficiency is high, and the reliability is high.

The invention discloses a mechanical power assisted braking system and a vehicle. The mechanical power assisted braking system comprises an operation device, an executing device and a mechanical powerassisting device, wherein the operation device comprises a brake pedal; the brake pedal can rotate around the rotation axis of the brake pedal; the executing device comprises an executing rod; the mechanical power assisting device is fitted between the operation device and the executing device; and the mechanical power assisting device is constructed as a lever type structure so that a braking force from the brake pedal is output to the executing rod under an amplifying effect of a lever. According to the mechanical power assisted braking system, the power assisting of the brake pedal is realized by using a mechanical structure; the structure is simple; the performance is stable; the cost is low; the maintenance is convenient; the engineering is easy to realize; and moreover, by using a lever labor-saving principle, a driver can brake the vehicle with smaller force so that the mechanical power assisted braking system is beneficial for running safety.

The invention discloses an embedded large-diameter concrete cylindrical structure and a construction method thereof. The cylindrical structure comprises a cylinder body, an annular substitute, a cylinder boot and a plurality of force transmission rods, wherein the cylinder body is of a reinforced concrete cylindrical structure; the annular substitute is installed above an upper end opening of the cylinder body and is collinear with the central axis of the cylinder body; the cylinder boot is fixedly installed at a lower end opening of the cylinder body, and the lower end of the cylinder boot is provided with a blade part; and the force transmission rods are arranged in the cylinder wall of the cylinder body, the central axes of the force transmission rods are parallel to the central axis of the cylinder body, the upper end parts and the lower end parts of the force transmission rods are fixedly connected with the annular substitute and the cylinder boot correspondingly, and the force transmission rods are uniformly arranged in the circumferential direction of the end opening of the cylinder body. The structure can replace a conventional steel cylinder revetment, the construction cost can be effectively reduced while the use requirements of a cylindrical revetment structure are met, and the structure has the advantages of being high in durability, rapid in construction, easy to manufacture in an engineering mode, small in influence on the environment and the like.

The invention proposes a construction method for a large-diameter steel-concrete composite cylindrical structure, comprising the following steps: making a steel cylinder and dowel bars: making a steel cylinder and a plurality of dowel bars, A gap is opened at the lower end of the steel cylinder; the installation of the dowel rod and the steel cylinder: the dowel rod is vertically inserted into the upper end of the steel cylinder through the gap to fix it; the installation of the support structure: the support structure includes A plurality of support rods arranged horizontally, one end of each support rod is respectively connected with a dowel rod, and the other end of the support rod intersects and is fixed on the central axis of the steel cylinder; the production and installation of the ring substitute: The ring-shaped substitute is fixedly connected with the upper end of the dowel bar; vibration and sinking construction: install the vibration-sinking tool for vibration-settling, and remove the ring-shaped substitute and supporting structure after the vibration-settling construction is completed; prefabrication of the concrete cylinder and installation of the concrete cylinder. The construction method can effectively reduce the construction cost, is easy to engineer and manufacture, and the obtained cylindrical structure has strong durability.