伴随着基因芯片的发展,通过研究海量的基因表达谱数据来识别肿瘤已成为生物信息学研究的热点.提出一种基于LoG(Laplace of Gaussian)矩阵分解的肿瘤基因特征提取方法,该方法首先将样本数据映射为高维空间中的点,然后构建点与点之间的LoG矩阵,在保留样本分类信息的情况下,使得无结构信息的基因表达谱数据变成具有结构信息的图,再对LoG权值矩阵进行非负矩阵分解得到能够表征样本特征的特征分量,最后用KNN对样本进行分类.通过对白血病和结肠癌基因表达谱数据的特征提取,验证该文方法的可行性和有效性.
For the purpose of investigating the nonlinear dynamics of the system,a fractional-order Chua's circuit based on the memristor deriving from the integer-order counterparts is provided. Firstly,according to the Lyapunov's indirect method,the stability analysis of the memristive system is made,and it shows that when the fractional-orders parameter of memristive system passes a critical value,the system loses the stability and bifurcation occurs. Then the bifurcation and chaos behaviors of fractional-order memristive system are show n using bifurcation diagrams w ith varying fractional orders of the system and other parameters. Furthermore,the chaotic behaviors of memristive chaotic system are proved by the waveform,phase plot and largest Lyapunov exponent diagram. Finally,theoretical results are illustrated and validated with the given numerical simulations.
Based on Lyapunov theorem and sliding mode control scheme,the chaos control of fractional memristor chaotic time⁃delay system was studied.In order to stabilize the system,a fractional sliding mode control method for fractional time⁃delay system was proposed.In addition,Lyapunov stability theorem was used to analyze the control scheme theoretically,which guaranteed the stability of commensurate and non⁃commensurate order systems with or without uncertainties and disturbances.Furthermore,to illustrate the feasibility of controller,the conditions for designing the controller parameters were derived.Finally,the simulation results presented the effectiveness of the designed strategy.
A sliding mode controller for a fractional-order memristor-based chaotic system is designed to address its problem in stabilization control.Firstly,aphysically realizable fractional-order memristive chaotic system was introduced,which can generate a complex dynamic behavior.Secondly,a sliding mode controller based on sliding mode theory along with Lyapunov stability theory was designed to guarantee the occurrence of the sliding motion.Furthermore,in order to demonstrate the feasibility of the controller,a condition was derived with the designed controller＇s parameters,and the stability analysis of the controlled system was tested.A theoretical analysis shows that,under suitable condition,the fractional-order memristive system with a sliding mode controller comes to a steady state.Finally,numerical simulations are shown to verify the theoretical analysis.It is shown that the proposed sliding mode method exhibits a considerable improvement in its applications in a fractional-order memristive system.
