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115results about How to "Delayed expansion" patented technology

Polymer-based stent assembly

Methods for preparing a polymer-based stent assembly comprising an inflatable balloon catheter and a polymer-based stent resistant to relaxation-related negative recoil are provided. The methods comprise heating a polymeric cylindrical device which is at a final predetermined shape and diameter to a temperature sufficiently above the glass transition temperature (Tg) of the polymer and for a time sufficient to erase any memory of previous processing of the polymeric cylindrical device and then quenching the polymeric cylindrical device to provide an educated polymeric cylindrical device having a memory of the final predetermined diameter and shape, mounting the educated cylindrical device on an inflatable balloon catheter, reducing the diameter of the educated cylindrical device by heating to a temperature at or slightly above the Tg of the polymer while evenly applying pressure on the exterior surface of the wall of the cylindrical device, and then cooling the cylindrical device below the Tg of the polymer to provide a stent assembly comprising an inflatable balloon catheter and an expandable, educated, polymeric stent snugly and stably disposed thereon. Assemblies comprising an inflatable balloon and a polymer based stent that is substantially resistant to relaxation related recoil mounted snugly on the balloon are also provided.
Owner:SAHAJANAND TECHNOLOGIES PRIVATE LTD

Polymer-based stent assembly

Methods for preparing a polymer-based stent assembly comprising an inflatable balloon catheter and a polymer-based stent resistant to relaxation-related negative recoil are provided. The methods comprise heating a polymeric cylindrical device which is at a final predetermined shape and diameter to a temperature sufficiently above the glass transition temperature (Tg) of the polymer and for a time sufficient to erase any memory of previous processing of the polymeric cylindrical device and then quenching the polymeric cylindrical device to provide an educated polymeric cylindrical device having a memory of the final predetermined diameter and shape, mounting the educated cylindrical device on an inflatable balloon catheter, reducing the diameter of the educated cylindrical device by heating to a temperature at or slightly above the Tg of the polymer while evenly applying pressure on the exterior surface of the wall of the cylindrical device, and then cooling the cylindrical device below the Tg of the polymer to provide a stent assembly comprising an inflatable balloon catheter and an expandable, educated, polymeric stent snugly and stably disposed thereon. Assemblies comprising an inflatable balloon and a polymer based stent that is substantially resistant to relaxation related recoil mounted snugly on the balloon are also provided.
Owner:SAHAJANAND TECHNOLOGIES PRIVATE LTD

Ultrahigh-strength high-toughness multistep isothermal bainite steel and preparation method thereof

ActiveCN103555896AAvoid changeIncreased ferriteHardnessUltimate tensile strength
The invention relates to an ultrahigh-strength high-toughness multistep isothermal bainite steel and a preparation method thereof. The technical scheme of the invention is as follows: a hot-rolled steel billet is austenitized 0.2-5.0 hours at a temperature of 850-1100 DEG C firstly, and then the steel billet is subjected to bainite multistep isothermal transformation, so that an ultrahigh-strength high-toughness multistep isothermal bainite steel is obtained. The multistep isothermal transformation is implemented through the following steps: 1, carrying out heat preservation 0.2-3.0 hours in an isothermal medium at a temperature of 250-450 DEG C; 2, carrying out heat preservation 2-50 hours in the isothermal medium at a temperature of 220-350 DEG C; 3, carrying out heat preservation 24-240 hours in the isothermal medium at a temperature of 180-250 DEG C; and 4, carrying out heat preservation 50-360 hours in the isothermal medium at a temperature of 150-220 DEG C, and cooling the obtained product to room temperature, wherein the multistep refers to step 1 to step 2, or step 1 to step 3, or step 1 to step 4. The bainite steel prepared by using the method disclosed by the invention has the characteristics of high hardness, high strength, high toughness, good volume stability and fine microstructure.
Owner:WUHAN UNIV OF SCI & TECH

Zirconium boride-silicon carbide laminated composite ultrahigh-temperature ceramic material and preparation method thereof

The invention discloses a zirconium boride-silicon carbide laminated composite ultrahigh-temperature ceramic material and a preparation method thereof, relating to a ultrahigh-temperature ceramic material and a preparation method thereof, wherein the material can be used for solving the problem that the existing boride ultrahigh-temperature ceramic matrix composite material has poor toughness. The zirconium boride-silicon carbide laminated composite ultrahigh-temperature ceramic material is prepared by laminating residual compressive stress layers and residual tensile stress layers alternatively. The preparation method comprises the following steps: 1. weighing raw materials; 2. preparing residual compressive stress layer powder and residual tensile stress layer powder; 3. preparing a laminated mixture; 4. carrying out sintering and heat insulation on the laminated mixture to obtain the zirconium boride-silicon carbide laminated composite ultrahigh-temperature ceramic material. The fracture toughness value of the zirconium boride-silicon carbide laminated composite ultrahigh-temperature ceramic material can reach up to 10.4MPaml / 2. In the invention, the preparation process is simple, the cost is low, and the fracture toughness is improved without influencing the strength of the material.
Owner:HARBIN INST OF TECH

JPEG image bit stream encryption method based on alternating current statistical characteristic change

The invention discloses a JPEG image bit stream encryption method based on alternating current statistical characteristic change. The method comprises: in a JPEG bit stream, a user selects the last non-zero communication coefficient entropy code in a part of image blocks by using a user key to encrypt; hiding the secret information into a part of image block entropy codes through a histogram translation method; statistical characteristics are obtained through a user secret key and an alternating current coefficient, a direct current coefficient encryption secret key and an alternating currentcoefficient encryption secret key are generated in a self-adaptive mode, inter-group scrambling and differential coding iteration scrambling are carried out on the direct current coefficient, and intra-block scrambling and inter-block scrambling are carried out on the alternating current coefficient; and the receiver extracts secret information from the encrypted bit stream and decrypts the secretinformation, recovers the direct current coefficient and the alternating current coefficient encryption key according to the user key and the alternating current coefficient statistical characteristics in the encrypted bit stream, decrypts the alternating current coefficient and the direct current coefficient, recovers the alternating current coefficient entropy code in each image block entropy code, and obtains the original bit stream. The method is high in security and small in encrypted file expansion.
Owner:SOUTHWEST JIAOTONG UNIV

Heat treatment process for wheel

The invention discloses a heat treatment process for a heavy-load wheel. The heat treatment process comprises the steps of: a, heating a rolled wheel; b, quenching the wheel; and c, tempering and cooling the wheel. In the heat treatment process for the heavy-load wheel, a quench cooling device used for quench cooling of the wheel is included, the quench cooling device comprises a carrier roller platform for supporting the wheel, nozzles for carrying out quench cooling on a wheel tread and a wheel rim surface, and a cooling mechanism for quench cooling of the nozzles; the wheel is placed on the carrier roller platform; the nozzles are evenly distributed in the circumferential direction of the carrier roller platform and connected with the cooling mechanism; carrier rollers rotate to drive the wheel to rotate; and quench cooling liquid is evenly sprayed on the wheel tread and the wheel rim surface. According to the quench cooling mode and the heat treatment process for the wheel, on the premise that the microstructure of conventional high-carbon steel AAR-C is still kept to be fine pearlite and a small amount of ferrite, the wheel has high hardness, high toughness and high plasticity at the same time, and the wear resistance and safety of the heavy-load wheel with the axle load of 40 tons are met.
Owner:MAANSHAN MAGANG JINXI RAIL TRANSPORT EQUIP
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