掺杂稀土铁磁性纳米复合粉体的制备

采用水热法以FeCl2和KOH为原料制备Fe3 O4粉体,以氧化钇、氧化铕和氧化铽为原料制备Y2 O3:1;Eu3+,5;Tb3+粉体,然后以Fe3 O4粉体,Y2 O3:1;Eu3+,5;Tb3+粉体和三聚氰胺为原料,采用微波烧结法在Ar气气氛下制备FeYO3/Y2 O3:1;Eu3+,5;Tb3+复合粉体,利用XRD衍射仪对各种粉体的结构进行分析,利用扫描电镜对复合粉体的形貌进行观察,并利用振动样品磁强计对复合粉体的磁学性能进行研究.结果表明:复合粉体均呈针状,长度和细度均为纳米级.当Fe3 O4,Y2 O3:1;Eu3+,5;Tb3+和三聚氰胺比例为1:3:4时,所制备的FeYO3/Y2 O3:1;Eu3+,5;Tb3+粉体磁力最强,磁力饱和强度为11.3 emu·g-1.     

FeYO3/Y2O3:1;Eu3+,1;Tb3+粉体的制备及其磁性研究

以FeCl2和KOH为原料采用水热法制备Fe3 O4粉体,然后以氧化钇、氧化铕和氧化铽为原料制备Eu3+,Tb3+共掺杂的Y2 O3荧光粉体,并通过XRD对粉体的物相结构进行分析;然后以三聚氰胺以及所制备的Fe3 O4和Y2 O3:Eu3+,Tb3+粉体为原料,采用微波烧结法在Ar气氛下制备FeYO3/Y2 O3:1;Eu3+,1;Tb3+粉体,并对其磁学性能进行了研究.研究结果表明:当Fe3 O4,Y2 O3:1;Eu3+,1;Tb3+和三聚氰胺比例为1:3:4时,所制备的FeYO3/Y2 O3:1;Eu3+,1;Tb3+粉体的磁力饱和强度为12.299 emu·g-1,磁力最强.     

A new hyperchaos system and its circuit simulation by EWB

This paper reports a new hyperchaotic system evolved from the three-dimensional L chaotic system. The Lyapunov exponents spectrum and the bifurcation diagram of this new hyperchaotic system are obtained. Hyperchaotic attractor, periodic orbit and chaotic attractor are obtained by computer simulation. A circuit is designed to realize this new hyperchaotic system by electronic workbench.     

片状hBN的制备及摩擦性能研究

以CaB2O4作为烧结助剂,采用热压烧结技术制备了片状hBN.通过SEM、XRD和摩擦磨损试验机对hBN块体的显微结构、物相组成和摩擦性能进行了表征.结果表明:在N2气气氛下,烧结温度为2000℃,保温时间为5h时,CaB2O4的加入可以有效的提高hBN的结晶性能.烧结hBN呈片状结构,其粒径约为0.5～2 μm,厚度约为200nm.hBN块体的摩擦系数和磨损量均随着温度的升高先增大后稍有降低,在600℃时,摩擦系数和磨损量均达到最高,其空气和水蒸气气氛下的摩擦系数分别为0.6和0.25,磨损量分别为9.1 mg和4.9 mg.在整个测试温度范围内,水蒸气气氛下的摩擦系数和磨损量均比空气气氛下低,这主要是因为:室温下,水蒸汽在hBN与摩擦副的摩擦表面形成一层水膜;高温下,hBN可以与水蒸汽发生反应,生成H3BO3.     

Realization of generalized synchronization between different chaotic systems via scalar controller

In this paper, a very simple generalized synchronization method between different chaotic systems is presented. Only a scalar controller is used in this method. The method of obtaining the scalar controller from chaotic systems is established. The sufficient and necessary condition of generalized synchronization is obtained from a rigorous theory, and the sufficient and necessary condition of generalized synchronization is irrelative to chaotic system itself. Theoretical analyses and simulation results show that the method established in this paper is effective.     

Function projective synchronization between fractional-order chaotic systems and integer-order chaotic systems

This paper investigates the function projective synchronization between fractional-order chaotic systems and integer-order chaotic systems using the stability theory of fractional-order systems. The function projective synchronization between three-dimensional (3D) integer-order Lorenz chaotic system and 3D fractional-order Chen chaotic system are presented to demonstrate the effectiveness of the proposed scheme.