Analogue Realizations of Fractional-Order Controllers

An approach to the design of analogue circuits, implementingfractional-order controllers, is presented. The suggestedapproach is based on the use of continued fraction expansions;in the case of negative coefficients in a continued fractionexpansion, the use of negative impedance converters is proposed.Several possible methods for obtaining suitable rational appromixationsand continued fraction expansions are discussed. An exampleof realization of a fractional-order I controlleris presented and illustrated by obtained measurements.The suggested approach can be used for the control of veryfast processes, where the use of digital controllers isdifficult or impossible.     

Affine geometry of special real submanifolds of Cn

In this paper we propose an affine analogue and generalization of the geometry of special Lagrangian submanifolds of Cⁿ.      

q-Anharmonic oscillator with quartic interaction

The first order perturbative correction to the energy levels of a boson realization of aq-oscillator due to a quartic term in the potential energy is evaluated. We also discuss the statistical mechanics ofq-anharmonic oscillators in the case where the parameterq deviates slightly from unity.     

Parallel surfaces in affine 4- space

We study affine immersions as introduced by Nomizu and Pinkall. We classify those affine immersions of a surface in R⁴ which are degenerate and have vanishing cubic form (i.e. parallel second fundamental form). This completes the classification of parallel surfaces of which the first results were obtained in the beginning of this century by Blaschke and his collaborators.     

The algebra ,η( ) and infinite Hopf family of algebras

New deformed affine algebras, _,η( ), are defined for any simply laced classical Lie algebra g, which are generalizations of the algebra, _,η( ₂), recently proposed by Khoroshkin-Lebedev-Pakuliak (KLP). Unlike the work of KLP, we associate with the new algebras the structure of an infinite Hopf family of algebras in contrast to the one containing only finite number of algebras, introduced by KLP. Bosonic representation for _,η( ) at level 1 is obtained, and it is shown that, by repeated application of Drinfeld-like comultiplications, a realization of _,η( ) at any positive integer level can be obtained. For the special case of g = sl_r+1, (r + 1)-dimensional evaluation representation is given. The corresponding interwining operations are also discussed.     

Affine minorants minimizing the sum of convex functions

It is often possible to replace a convex minimization problem by an equivalent one, in which each of the original convex functions is replaced by a suitably chosen affine minorant. In this paper we identify essentially the minimal conditions permitting this replacement, and also shed light on the close and complete link between such optimal affine minorants and certain optimal dual vectors. An application to the ordinary convex programming problem is included.This research was supported in part by the National Science Foundation, Grant No. MPS75-08025, at the University of Illinois at Urbana-Champaign.     

素特征域上无扭仿型李代数的实现

在有单位元的可换环上研究仿型李代数有两种定义，一种是应用生成元和定义关系的方法［１］；另一种是应用Ｃｈｅｖａｌｌｅｙ生成元的张量扩张的方法［２］．本文做了以下两方面的工作：（ｉ）＃第一种方法应用到罗朗多项式环上，由素特征ｐ≠２，３的域上典型单李代数出发进行一维中心扩张得到无扭仿型李代数的实现，定理２．６．（ｉｉ）证明了以上两种方法定义的李代数在素特征ｐ≠２，３的域上是同构的．     

新三维混沌系统及其电路仿真实验

提出了一个混沌系统，并对该系统的基本动力学特性进行了深入研究.得到该系统的Lyapunov指数、Lyapunov维数，给出了Poincaré映射图以及时域图和相图. 运用电子工作平台EWB软件对实现该新混沌系统的振荡器电路进行了仿真实验. 经过数值仿真和电路系统仿真证实该系统与以往发现的混沌吸引子并不拓扑等价，属于新的混沌系统. 关键词： 混沌系统 动力学行为 电路实现