It is very important for reactor design and control to choose and control the temperature throughout the reaction process.The linear stability analysis showed that control parameters contained in a nonlinear kinetic s...It is very important for reactor design and control to choose and control the temperature throughout the reaction process.The linear stability analysis showed that control parameters contained in a nonlinear kinetic system of equations resulted in the diversity of temperature self-organization structures and occurring critical values in Lindemann uni-molecular chemical reaction-diffusion-heat conduction systems.The results of numerical simulations also showed that the differences of occurring critical values of Turing bifurcation led to multiple wave number values of spatially periodic structures of temperature field.Without doubt,these significant results should be considered in order to reasonably design,correctly choose the reactor type and optimally control chemical reactors.展开更多
The electroplastic effect in AZ31B magnesium alloy sheet was investigated through uniaxial tensile tests. In order to show the athermal effect of the electrical pulses, two types of uniaxial tensile tests at the same ...The electroplastic effect in AZ31B magnesium alloy sheet was investigated through uniaxial tensile tests. In order to show the athermal effect of the electrical pulses, two types of uniaxial tensile tests at the same testing temperature were carried out： uniaxial tension in environmental cabinet and uniaxial tension with electrical pulses. In addition, the distribution of temperature field in the cross-section area during uniaxial tension with electrical pulses was simulated. The results show that the distribution of temperature field along the cross-section area is homogeneous. By comparing the true stress？true strain curves of AZ31B alloy under uniaxial tensile tests, the athermal effect with electrical pulses was confirmed. The microstructure evolution after the uniaxial tension was studied by optical microscopy. The results indicate that the electrical pulses induced dynamic recrystallization plays an important role in the decrease of flow stress. Finally, a flow stress model of AZ31B sheet taking the influence of electroplastic effect into account was proposed and validated. The results demonstrate that the calculated data fit the experimental data well.展开更多
Numerical simulation and experiments were introduced to develop AA4045/AA3003 cladding billets with different clad-ratios. The temperature fields, microstructures and mechanical properties near interface were investig...Numerical simulation and experiments were introduced to develop AA4045/AA3003 cladding billets with different clad-ratios. The temperature fields, microstructures and mechanical properties near interface were investigated in detail. The results show that cladding billets with different clad-ratios were fabricated successfully. Si and Mn elements diffused across the bonding interface and formed diffusion layer. With the increase of clad-layer thickness, the interfacial region transforms from semisolid-solid state to liquid-solid state and the diffusion layer increased from 10 to 25 μm. The hardness at interface is higher than that of AA3003 side but lower than that of the other side. The bonding strength increased with the clad-layer thickness, attributing to solution strengthening due to elements diffusion. The cladding billets were extruded into clad pipe by indirect extrusion process after homogenization. The clad pipe remained the interfacial characteristics of as-cast cladding billet and the heredity of clad-ratio during deformation was testified.展开更多
A 3D temperature field distribution of biological tissue for superficial hyperthermia using a pulse modulated microwave （PMMW） was presented. A 3D sliced homogeneous phantom was radiated by the PMMW and an infrared ...A 3D temperature field distribution of biological tissue for superficial hyperthermia using a pulse modulated microwave （PMMW） was presented. A 3D sliced homogeneous phantom was radiated by the PMMW and an infrared thermal imager was applied to image temperature distribution throughout the phantom. The period of the PMMW is 3 s and the output power is 35 W. The temperature rises by at least 3 ℃ in the phantom when the duty cycle varies from 1/3, 1/2, 2/3 to 1 （denoted by scenarios 1-4）. Both the accumulative temperature-volume histogram and the relative depth-area ratio histogram show that the maximum temperature rise （MTR） is 6.6 and 8 ℃ in scenarios 2 and 3, and they are superior to scenarios 1 and 4. Furthermore, the PMMW can control temperature field distribution of biological tissue. It provides both preliminary basis for thermal volume control and new technology for temperature control and monitor in superficial hyperthermia.展开更多
The influence of the low voltage pulsed magnetic field(LVPMF)on the microstructure transition of K4169 superalloy was investigated.The gradient microstructure of K4169 superalloy composed of columnar grains,coarse gra...The influence of the low voltage pulsed magnetic field(LVPMF)on the microstructure transition of K4169 superalloy was investigated.The gradient microstructure of K4169 superalloy composed of columnar grains,coarse grains,and fine grains was prepared through the combined method of LVPMF with directional solidification,which provided a new approach for the preparation of superalloy with gradient microstructure.The distribution of the Lorentz force and flow field under LVPMF effect was simulated,and therefore the microstructure transition mechanism was revealed.Results show that the microstructure transition should be attributed to the coupling effects of the Lorentz force and forced convection.展开更多
文摘It is very important for reactor design and control to choose and control the temperature throughout the reaction process.The linear stability analysis showed that control parameters contained in a nonlinear kinetic system of equations resulted in the diversity of temperature self-organization structures and occurring critical values in Lindemann uni-molecular chemical reaction-diffusion-heat conduction systems.The results of numerical simulations also showed that the differences of occurring critical values of Turing bifurcation led to multiple wave number values of spatially periodic structures of temperature field.Without doubt,these significant results should be considered in order to reasonably design,correctly choose the reactor type and optimally control chemical reactors.
基金Projects(50975174,51275297)supported by the National Natural Science Foundation of ChinaProject(20100073110044)supported by the Education Ministry of China
文摘The electroplastic effect in AZ31B magnesium alloy sheet was investigated through uniaxial tensile tests. In order to show the athermal effect of the electrical pulses, two types of uniaxial tensile tests at the same testing temperature were carried out： uniaxial tension in environmental cabinet and uniaxial tension with electrical pulses. In addition, the distribution of temperature field in the cross-section area during uniaxial tension with electrical pulses was simulated. The results show that the distribution of temperature field along the cross-section area is homogeneous. By comparing the true stress？true strain curves of AZ31B alloy under uniaxial tensile tests, the athermal effect with electrical pulses was confirmed. The microstructure evolution after the uniaxial tension was studied by optical microscopy. The results indicate that the electrical pulses induced dynamic recrystallization plays an important role in the decrease of flow stress. Finally, a flow stress model of AZ31B sheet taking the influence of electroplastic effect into account was proposed and validated. The results demonstrate that the calculated data fit the experimental data well.
基金Project(2015B090926013)supported by the Science and Technology Program of Guangdong Province,ChinaProject(20170540307)supported by the Natural Science Foundation of Liaoning Province,China
文摘Numerical simulation and experiments were introduced to develop AA4045/AA3003 cladding billets with different clad-ratios. The temperature fields, microstructures and mechanical properties near interface were investigated in detail. The results show that cladding billets with different clad-ratios were fabricated successfully. Si and Mn elements diffused across the bonding interface and formed diffusion layer. With the increase of clad-layer thickness, the interfacial region transforms from semisolid-solid state to liquid-solid state and the diffusion layer increased from 10 to 25 μm. The hardness at interface is higher than that of AA3003 side but lower than that of the other side. The bonding strength increased with the clad-layer thickness, attributing to solution strengthening due to elements diffusion. The cladding billets were extruded into clad pipe by indirect extrusion process after homogenization. The clad pipe remained the interfacial characteristics of as-cast cladding billet and the heredity of clad-ratio during deformation was testified.
基金Project(50977064) supported by the National Natural Science Foundation of China
文摘A 3D temperature field distribution of biological tissue for superficial hyperthermia using a pulse modulated microwave （PMMW） was presented. A 3D sliced homogeneous phantom was radiated by the PMMW and an infrared thermal imager was applied to image temperature distribution throughout the phantom. The period of the PMMW is 3 s and the output power is 35 W. The temperature rises by at least 3 ℃ in the phantom when the duty cycle varies from 1/3, 1/2, 2/3 to 1 （denoted by scenarios 1-4）. Both the accumulative temperature-volume histogram and the relative depth-area ratio histogram show that the maximum temperature rise （MTR） is 6.6 and 8 ℃ in scenarios 2 and 3, and they are superior to scenarios 1 and 4. Furthermore, the PMMW can control temperature field distribution of biological tissue. It provides both preliminary basis for thermal volume control and new technology for temperature control and monitor in superficial hyperthermia.
基金National Key Research and Development Program of China(2018YFA0702900)National Science and Technology Major Project(J2019-VII-0002-0142)National Natural Science Foundation of China(51831007)。
文摘The influence of the low voltage pulsed magnetic field(LVPMF)on the microstructure transition of K4169 superalloy was investigated.The gradient microstructure of K4169 superalloy composed of columnar grains,coarse grains,and fine grains was prepared through the combined method of LVPMF with directional solidification,which provided a new approach for the preparation of superalloy with gradient microstructure.The distribution of the Lorentz force and flow field under LVPMF effect was simulated,and therefore the microstructure transition mechanism was revealed.Results show that the microstructure transition should be attributed to the coupling effects of the Lorentz force and forced convection.
