锂离子电池高电压正极材料LiNiVO4的合成与表征

通过流变相反应法成功合成了LiNiVO4．利用热重-差热分析、粉末X射线衍射、扫描电子显微镜和粒度分析对产物进行了表征;采用循环伏安技术评价了其电化学性能．结果表明,利用流变相反应法在500℃即可制备纯相的LiNiVO4产物．与常规的固相反应产物相比,流变相产物表现出了较小的晶胞常数和颗粒尺寸,其中600℃的流变相产物具有良好的循环伏安特性．     

FitzHugh-Nagumo系统中螺旋波的控制

采用FitzHugh-Nagumo方程,研究了二维时空系统中螺旋波的控制问题,利用相空间压缩方法对部分系统变量的振幅进行限制从而影响螺旋波的稳定性.研究表明,控制过程可分为三个不同的阶段:在较小压缩限条件下螺旋波可以被完全消除,系统进入均匀定态;在较大的压缩限条件下螺旋波能够稳定存在,而且其振荡频率不随控制参数的改变而发生变化;当压缩限介于上述两者之间时,系统表现为时空混沌态.对上述控制过程进行了进一步的讨论,研究了不同控制参数条件下的系统斑图、变量的演化、相空间轨道等性质,并且对振幅函数和振荡频率特征进 关键词： 螺旋波 相空间压缩 FitzHugh-Nagumo方程     

Synchronizing spiral waves in a coupled Rssler system

The synchronisation of spiral patterns in a drive-response Rssler system is studied.The existence of three types of synchronisation is revealed by inspecting the coupling parameter space.Two transient stages of phase synchronisation and partial synchronisation are observed in a comparatively weak feedback coupling parameter regime,whilst complete synchronisation of spirals is found with strong negative couplings.Detailed observations of the synchronous process,such as oscillatory frequencies,parameters mismatches and amplitude variations,etc,are investigated via numerical simulations.     

软化学技术合成高容量锂二次电池正极材料AgV_3O_8(英文)

应用软化学方法合成层状AgV3O8正极材料,并用XRD(粉末X-射线衍射)、SEM(扫描电子显微镜)和LPSA(激光粒度分析)表征了材料的结构和形貌,采用恒流充放电技术研究了其电化学性能.SEM和LPSA测试结果显示所制备的材料具有较小的颗粒尺寸和较窄的粒度分布区间.恒流充放电测试结果表明,该材料具有高的放电比容量,其中400 ℃下获得的材料首次放电容量高达760.5 mAh/g.     

Size transition of spiral waves using the pulse array method

The domain size of spiral waves is an important issue in studies of two-dimensional (2D) spatiotemporal patterns.In this work,we use the 2D complex Ginzburg-Landau equation (CGLE) as our model and find that an initially big spiral can successfully transfer to several small spirals by applying a pulse array method.The impacts of several important factors,such as array density,controlling intensity and pulsing time,are investigated.This control approach may be useful for the control of 2D spatiotemporal patterns and has potential applications in the control of some realistic systems,such as meteorological and cardiac systems.     

利用速度反馈方法控制时空混沌

以空间一维的复Ginzburg-Landau方程为模型，研究了利用系统变量随时间的变化率作为反馈控制信号控制偏微分方程系统中时空混沌的可能性.通过理论分析和数值模拟方法讨论了控制参数与可控性所满足的关系，解释了不同目标态时临界控制参数的尺寸效应. 关键词： 混沌控制 时空混沌 速度反馈 复Ginzburg-Landau方程     

Amplitude wave in one-dimensional complex Ginzburgben Landau equation

The wave propagation in the one-dimensional complex Ginzburg-Landau equation (CGLE) is studied by considering a wave source at the system boundary. A special propagation region, which is an island-shaped zone surrounded by the defect turbulence in the system parameter space, is observed in our numerical experiment. The wave signal spreads in the whole space with a novel amplitude wave pattern in the area. The relevant factors of the pattern formation, such as the wave speed, the maximum propagating distance and the oscillatory frequency, are studied in detail. The stability and the generality of the region are testified by adopting various initial conditions. This finding of the amplitude pattern extends the wave propagation region in the parameter space and presents a new signal transmission mode, and is therefore expected to be of much importance.     

Synchronizing spiral waves in a coupled Rossler system

The synchronisation of spiral patterns in a drive-response R6ssler system is studied. The existence of three types of synchronisation is revealed by inspecting the coupling parameter space. Two transient stages of phase synchronisation and partial synchronisation are observed in a comparatively weak feedback coupling parameter regime, whilst complete synchronisation of spirals is found with strong negative couplings. Detailed observations of the synchronous process, such as oscillatory frequencies, parameters mismatches and amplitude variations, etc, are investigated via numerical simulations.     

电压模式控制不连续传导模式 boost变换器切分岔研究

电压模式控制boost变换器能产生多种分岔形式,对其分岔中的一类重要的切分岔现象进行了详细研究. 首先根据系统的一次离散迭代映射推导出其三次离散迭代映射模型,基于非线性系统理论中的切分岔定理, 从数学上推导出此类变换器产生切分岔现象的条件,并通过数值仿真研究了电路参数对这类变换器切分岔现象的影响.研究结果表明:当系统的反馈系数处在一定范围内时,该类变换器会出现切分岔和阵发混沌现象. 最后通过实验研究boost变换器中存在的这类不稳定非线性现象,验证了理论分析和数值仿真的正确性.     

Zn_(0.97)Cr_(0.03)O的PLD制备及其铁磁性

采用脉冲激光沉积(PLD)的方法在石英基片上制备了不同氧分压(0,0.05,0.15和0.20 Pa)下Zn0.97Cr0.03O薄膜,并测量了它们的磁性、XRD谱、PL谱及XPS谱等.实验结果表明,所有的样品都具有良好的结晶性,且都沿c轴高度取向;磁测量结果表明,四个样品都具有铁磁性,且在氧压为0.15 Pa下沉积的薄膜磁性最强;四个样品都存在VZn,Oi,Zni,VZn,VO缺陷,尤其是VZn对应共振峰面积占所有缺陷总面积的百分比和样品的饱和磁化强度具有相同的变化趋势,表明Zn0.97Cr0.03O磁性与锌空位密切相关;四个样品中都存在Cr3+离子,且在0.15 Pa时Cr3+的含量最多.上述实验结果表明,Cr3+和VZn的缺陷复合体是ZnO:Cr样品具有稳定的铁磁有序的最有利条件,它证实了早先的基于第一性原理的计算结果.