A new rare earth magnesium alloy(Mg-6 Zn-4 Sm-0.4 Zr, wt.%) was prepared by permanent mould casting. The microstructure and mechanical properties of the alloy sample in as-cast and various heat treatment situations we...A new rare earth magnesium alloy(Mg-6 Zn-4 Sm-0.4 Zr, wt.%) was prepared by permanent mould casting. The microstructure and mechanical properties of the alloy sample in as-cast and various heat treatment situations were characterized with an optical microscope(OM), X-ray diffractometer(XRD), scanning electron microscope(SEM) equipped with energy dispersive spectroscope(EDS), transmission electron microscope(TEM) and mechanical tests at room temperature, respectively. The experimental results show that the as-cast alloy mainly consists of α-Mg, eutectic Mg_2Zn_3, MgZnSm and Mg_(41)Sm_5. These eutectic phases with continuous or semicontinuous morphology principally distribute along grain boundaries. Almost all the eutectic compounds dissolve in α-Mg and the grains have no obvious growth trend after optimum solution treatment at 490 °C for 18 h. Meanwhile, the ultimate tensile strength(UTS) of 229 MPa and elongation(EL) to rupture of 9.78% can be achieved through the optimal solution treatment, which increase by 37 MPa and 57.74%, respectively, compared with that of the as-cast alloy. Further aging treatments at 200 °C for different durations lead to the conspicuous increment of mechanical properties and prominent age-hardening response. Peak-aged alloy(treated at 200 °C for 12 h) reveals better mechanical properties(UTS 258 MPa, EL 9.42%, hardness 73.4 HV) compared with the same alloy treated in other aging conditions, which is mainly ascribed to precipitated Mg_2Zn_3 and MgZn_2 phases. Fracture analysis demonstrates that the as-cast alloy belongs to inter-granular and cleavage fracture patterns, while the solutionized alloy(treated at 490 °C for 18 h) reveals trans-granular and quasi-cleavage fracture modes. For the peak-aged alloy, the fracture pattern obeys the mixture of trans-granular and cleavage modes.展开更多
The implementation of a missile's visual simulation system is explained that is developed with OpenGL(open graphic library) and the flight path and flight carriage in different stages of the missile are displayed....The implementation of a missile's visual simulation system is explained that is developed with OpenGL(open graphic library) and the flight path and flight carriage in different stages of the missile are displayed. The establishment problems of the 3D scene are circumstantiated including the construction and redeployment of the model, creation of the virtual scene, setting of the multi-viewports and multi-windows etc. The missile's data driver, system flow, the modules and their mutual relations of the missile visual simulation system are discussed. The missile flight simulation results and effect of the scenes are given.展开更多
应用倾斜转弯(Bank to Turn,BTT)及推力矢量控(ThrustVector Control,TVC)技术设计并建立了空空导弹六自由度模型。在此基础上考虑气动参数变化和建模不确定性引起的误差对导弹控制系统的影响,为消除误差影响,引入RBF神经网络分别对快...应用倾斜转弯(Bank to Turn,BTT)及推力矢量控(ThrustVector Control,TVC)技术设计并建立了空空导弹六自由度模型。在此基础上考虑气动参数变化和建模不确定性引起的误差对导弹控制系统的影响,为消除误差影响,引入RBF神经网络分别对快慢回路进行补偿,利用李亚普诺夫(Lyapunov)稳定性定理推导了神经网络权值、中心及带宽的自适应规律,并证明了闭环系统的稳定性。通过对某型空空导弹大机动仿真研究,结果表明RBF神经网络自适应控制方法补偿作用显著,不仅改善了控制系统的动态性能,而且使系统具有良好的抗干扰和容错能力。展开更多
基金financially supported by the National Nature Science Foundations of China(51464032)National Basic Research Program of China(Grant No.2010CB635106)
文摘A new rare earth magnesium alloy(Mg-6 Zn-4 Sm-0.4 Zr, wt.%) was prepared by permanent mould casting. The microstructure and mechanical properties of the alloy sample in as-cast and various heat treatment situations were characterized with an optical microscope(OM), X-ray diffractometer(XRD), scanning electron microscope(SEM) equipped with energy dispersive spectroscope(EDS), transmission electron microscope(TEM) and mechanical tests at room temperature, respectively. The experimental results show that the as-cast alloy mainly consists of α-Mg, eutectic Mg_2Zn_3, MgZnSm and Mg_(41)Sm_5. These eutectic phases with continuous or semicontinuous morphology principally distribute along grain boundaries. Almost all the eutectic compounds dissolve in α-Mg and the grains have no obvious growth trend after optimum solution treatment at 490 °C for 18 h. Meanwhile, the ultimate tensile strength(UTS) of 229 MPa and elongation(EL) to rupture of 9.78% can be achieved through the optimal solution treatment, which increase by 37 MPa and 57.74%, respectively, compared with that of the as-cast alloy. Further aging treatments at 200 °C for different durations lead to the conspicuous increment of mechanical properties and prominent age-hardening response. Peak-aged alloy(treated at 200 °C for 12 h) reveals better mechanical properties(UTS 258 MPa, EL 9.42%, hardness 73.4 HV) compared with the same alloy treated in other aging conditions, which is mainly ascribed to precipitated Mg_2Zn_3 and MgZn_2 phases. Fracture analysis demonstrates that the as-cast alloy belongs to inter-granular and cleavage fracture patterns, while the solutionized alloy(treated at 490 °C for 18 h) reveals trans-granular and quasi-cleavage fracture modes. For the peak-aged alloy, the fracture pattern obeys the mixture of trans-granular and cleavage modes.
文摘The implementation of a missile's visual simulation system is explained that is developed with OpenGL(open graphic library) and the flight path and flight carriage in different stages of the missile are displayed. The establishment problems of the 3D scene are circumstantiated including the construction and redeployment of the model, creation of the virtual scene, setting of the multi-viewports and multi-windows etc. The missile's data driver, system flow, the modules and their mutual relations of the missile visual simulation system are discussed. The missile flight simulation results and effect of the scenes are given.
文摘应用倾斜转弯(Bank to Turn,BTT)及推力矢量控(ThrustVector Control,TVC)技术设计并建立了空空导弹六自由度模型。在此基础上考虑气动参数变化和建模不确定性引起的误差对导弹控制系统的影响,为消除误差影响,引入RBF神经网络分别对快慢回路进行补偿,利用李亚普诺夫(Lyapunov)稳定性定理推导了神经网络权值、中心及带宽的自适应规律,并证明了闭环系统的稳定性。通过对某型空空导弹大机动仿真研究,结果表明RBF神经网络自适应控制方法补偿作用显著,不仅改善了控制系统的动态性能,而且使系统具有良好的抗干扰和容错能力。
