Spindly calcium carbonate coated with AlOOH has been successfully prepared by bubbling carbonization method. SEM and XRD analysis results suggested an amorphous filiform the coating layer of AlOOH. Inverse gas chromat...Spindly calcium carbonate coated with AlOOH has been successfully prepared by bubbling carbonization method. SEM and XRD analysis results suggested an amorphous filiform the coating layer of AlOOH. Inverse gas chromatography (IGC) analysis indicated that γsD, the London component of surface energy of calcium carbonate increased after being coated with AlOOH, especially when with the coating weight quantity of 4%. And the reduction of the γsD value with the ascending column temperature became more obvious along with the increase of the coating weight quantity, which might be due to the desorption of water from the surface. In addition, the surface acid- alkali capacity of calcium carbonate also increased after coating.展开更多
An impact angle constrained fuzzy adaptive fault tolerant integrated guidance and control method for Ski-to-Turn(STT)missiles subject to unsteady aerodynamics and multiple disturbances is proposed.Unsteady aerodynamic...An impact angle constrained fuzzy adaptive fault tolerant integrated guidance and control method for Ski-to-Turn(STT)missiles subject to unsteady aerodynamics and multiple disturbances is proposed.Unsteady aerodynamics appears when flight vehicles are in a transonic state or confronted with unstable airflow.Meanwhile,actuator failures and multisource model uncertainties are introduced.However,the boundaries of these multisource uncertainties are assumed unknown.The target is assumed to execute high maneuver movement which is unknown to the missile.Furthermore,impact angle constraint puts forward higher requirements for the interception accuracy of the integrated guidance and control(IGC)method.The impact angle constraint and the precise interception are established as the object of the IGC method.Then,the boundaries of the lumped disturbances are estimated,and several fuzzy logic systems are introduced to compensate the unknown nonlinearities and uncertainties.Next,a series of adaptive laws are developed so that the undesirable effects arising from unsteady aerodynamics,actuator failures and unknown uncertainties could be suppressed.Consequently,an impact angle constrained fuzzy adaptive fault tolerant IGC method with three loops is constructed and a perfect hit-to-kill interception with specified impact angle can be implemented.Eventually,the numerical simulations are conducted to verify the effectiveness and superiority of the proposed method.展开更多
针对拦截空中目标的场景,提出一种考虑攻击角度的制导控制一体化(integrated guidance and control,IGC)方法,同时考虑输入饱和以及攻角的约束问题。首先,在俯仰平面下对包含不确定性的系统进行了建模。基于反演法和指令滤波器,处理了...针对拦截空中目标的场景,提出一种考虑攻击角度的制导控制一体化(integrated guidance and control,IGC)方法,同时考虑输入饱和以及攻角的约束问题。首先,在俯仰平面下对包含不确定性的系统进行了建模。基于反演法和指令滤波器,处理了攻击角度约束问题和执行器机械限制的输入饱和问题,设计了含误差积分反馈的补偿项以处理跟踪误差,引入了障碍Lyapunov函数将攻角约束在预设区间。基于Lyapunov理论证明了闭环系统的稳定性和变量的有界性,以及各约束条件的成立性。仿真实验表明,方法能够以预设角度有效拦截目标,过程满足对输入以及攻角的约束条件,同时具备较强的鲁棒性。展开更多
导电银浆是一种重要的电子材料,可以提高电子器件的连接和传输效率,广泛应用于太阳能和电子工业领域。目前导电银浆的制作流程繁琐,通常使用纳米银等成本较高的填料以保证良好的导电性。本研究采用惰性气体冷凝(inert gas condensation,...导电银浆是一种重要的电子材料,可以提高电子器件的连接和传输效率,广泛应用于太阳能和电子工业领域。目前导电银浆的制作流程繁琐,通常使用纳米银等成本较高的填料以保证良好的导电性。本研究采用惰性气体冷凝(inert gas condensation, IGC)法制备了纳米晶/非晶复合铜锆银(Cu-Zr-Ag)粉,通过X射线衍射(XRD)、场发射扫描电镜(FESEM)、透射电镜(TEM)等方式对其微观结构和形貌进行了表征,并将其作为导电填料制备了导电银浆,测量了含有不同复合Cu-Zr-Ag粉添加量的导电银浆高温烧结后样品的导电性。结果表明:通过IGC法制备的纳米晶/非晶复合Cu-Zr-Ag粉尺寸分布均匀,平均尺寸约为35 nm;纳米晶/非晶复合Cu-Zr-Ag粉添加量为0.5%~1.5%的导电银浆导电性得到优化,其中,纳米粉的添加量为1%时,方阻最低,达到5.63 mΩ/□。展开更多
文摘Spindly calcium carbonate coated with AlOOH has been successfully prepared by bubbling carbonization method. SEM and XRD analysis results suggested an amorphous filiform the coating layer of AlOOH. Inverse gas chromatography (IGC) analysis indicated that γsD, the London component of surface energy of calcium carbonate increased after being coated with AlOOH, especially when with the coating weight quantity of 4%. And the reduction of the γsD value with the ascending column temperature became more obvious along with the increase of the coating weight quantity, which might be due to the desorption of water from the surface. In addition, the surface acid- alkali capacity of calcium carbonate also increased after coating.
基金supported by the National Natural Science Foundation of China(62003264).
文摘An impact angle constrained fuzzy adaptive fault tolerant integrated guidance and control method for Ski-to-Turn(STT)missiles subject to unsteady aerodynamics and multiple disturbances is proposed.Unsteady aerodynamics appears when flight vehicles are in a transonic state or confronted with unstable airflow.Meanwhile,actuator failures and multisource model uncertainties are introduced.However,the boundaries of these multisource uncertainties are assumed unknown.The target is assumed to execute high maneuver movement which is unknown to the missile.Furthermore,impact angle constraint puts forward higher requirements for the interception accuracy of the integrated guidance and control(IGC)method.The impact angle constraint and the precise interception are established as the object of the IGC method.Then,the boundaries of the lumped disturbances are estimated,and several fuzzy logic systems are introduced to compensate the unknown nonlinearities and uncertainties.Next,a series of adaptive laws are developed so that the undesirable effects arising from unsteady aerodynamics,actuator failures and unknown uncertainties could be suppressed.Consequently,an impact angle constrained fuzzy adaptive fault tolerant IGC method with three loops is constructed and a perfect hit-to-kill interception with specified impact angle can be implemented.Eventually,the numerical simulations are conducted to verify the effectiveness and superiority of the proposed method.
文摘针对拦截空中目标的场景,提出一种考虑攻击角度的制导控制一体化(integrated guidance and control,IGC)方法,同时考虑输入饱和以及攻角的约束问题。首先,在俯仰平面下对包含不确定性的系统进行了建模。基于反演法和指令滤波器,处理了攻击角度约束问题和执行器机械限制的输入饱和问题,设计了含误差积分反馈的补偿项以处理跟踪误差,引入了障碍Lyapunov函数将攻角约束在预设区间。基于Lyapunov理论证明了闭环系统的稳定性和变量的有界性,以及各约束条件的成立性。仿真实验表明,方法能够以预设角度有效拦截目标,过程满足对输入以及攻角的约束条件,同时具备较强的鲁棒性。
