Prediction of dynamic voltage stability status based on Hopf and limit induced bifurcations using extreme learning machine

Evaluation of voltage stability status considering its dynamic boundaries is a key issue for saving global stability of power systems. However, this evaluation is a computationally demanding task and its implementation is very hard (if not impossible) for on-line environments such as dispatching centers of power systems. In this paper, a new viewpoint for the problem based on modeling it as a forecast process is proposed, which can be implemented with a low computation burden for practical power systems. For this purpose, a voltage stability classification model considering Hopf and limit induced bifurcations is proposed and a new forecast strategy to predict voltage stability class label based on the proposed classification is suggested. The suggested forecast strategy is composed of an information theoretic feature selection technique, extreme learning machine (ELM) as the forecast engine and a line search procedure to fine-tune the settings. The effectiveness of the proposed classification model and forecast strategy is extensively illustrated on the New England 39-bus and IEEE 145-bus test systems.     

Two‐Parameter Continuation and Bifurcation Strategies for Oscillatory Behavior Elimination from a Zymomonas mobilis Fermentation System

Two‐parameter continuation and bifurcation analysis strategies were applied to deal with the oscillatory phenomena of a Zymomonas mobilis ethanol fermentation system. A structured verified non‐linear mathematical model considering the physiological limitations of microorganisms for a single continuous fermenter for ethanol production using Z. mobilis was built to identify the Hopf bifurcation (HB) points, which indicate the oscillatory behavior, using the inlet substrate concentration and the dilution rate as bifurcation parameters. The path of the HB points can be determined with different controlling operating parameters. It was found that with the addition of a small amount of cells or ethanol to the feed stream or by increasing the dilution rate, the oscillations could be eliminated and steady‐state behavior was attained. Using a two‐parameter continuation strategy, the Z. mobilis fermentation system could operate at steady state without oscillatory behavior.     

Hopf Bifurcation Analysis and Control for Electrical System of Military Vehicle

Electrical system of military vehicle is a typical parameterized nonlinear system where complicated bifurcations may exist and threaten its safe and stable operation. An algebraic criterion for Hopf bifurcation is presented briefly and applied to find Hopf bifurcation point of the electrical system with automatic voltage regulator （AVR） dynamics in military vehicle. Hopf bifurcation controllers are designed for this electrical system by using wash-out filter, linear feedback, non- linear feedback and their combination. The linear feedback control makes the system bring Hopf bifurcation at preferable parameter, the nonlinear feedback control modifies the type of the bifurcation, and the wash-out filter enhances the system damping, thus, the Hopf bifurcation is eliminated and the electrical system stability is ensured. Simulation results show the controller＇s validity.     

Complete and ready simulation semantics are not finitely based over BCCSP, even with a singleton alphabet

This note shows that the complete and the ready simulation preorders do not have a finite inequational basis over the language BCCSP when the set of actions is a singleton. Moreover, the equivalences induced by those preorders do not have a finite (in)equational axiomatization either. These results are in contrast with a claim of finite axiomatizability for those semantics in the literature, which was based on the erroneous assumption that they coincide with complete trace semantics in the presence of a singleton set of actions.     

右-右缠绕模范畴M_A~C(Ψ)中的扭曲

主要推广了关于相关Hopf模的扭曲理论到缠绕模上,证明(A,C,Ψ)上的右-右缠绕模范畴MCA(Ψ)同构于(Aτ,C,Ψ)上的右-右缠绕模范畴MACτ(Ψ),从而发展了缠绕模的理论。     

Weak pseudo-Wajsberg and weak pseudo-MV algebras

 We introduce and study a generalization of pseudo-Wajsberg and pseudo-MV algebras. The weakening of the axioms leads to the existence of two lattice structures, and of two multiplicative monoid structures. Some categorical equivalences are established.     

A characterization of computable analysis on unbounded domains using differential equations

The functions of computable analysis are defined by enhancing normal Turing machines to deal with real number inputs. We consider characterizations of these functions using function algebras, known as real recursive functions. Since there are numerous incompatible models of computation over the reals, it is interesting to find that the two very different models we consider can be set up to yield exactly the same functions. Bournez and Hainry used a function algebra to characterize computable analysis, restricted to the twice continuously differentiable functions with compact domains. In our earlier paper, we found a different (and apparently more natural) function algebra that also yields computable analysis, with the same restriction. In this paper we improve earlier work, finding three function algebras characterizing computable analysis, removing the restriction to twice continuously differentiable functions and allowing unbounded domains. One of these function algebras is built upon the widely studied real primitive recursive functions. Furthermore, the proof of this paper uses our previously developed method of approximation, whose applicability is further evidenced by this paper.     

一种求解电力系统动态电压稳定Hopf分岔点的新型混合方法

求解非线性动力系统Hopf分岔点的方法主要有连续法和直接法两种,提出了一种求解Hopf分岔点的混合方法,并应用到电力系统动态电压稳定分析中.以描述电力系统动态特性的微分方程(ODE)为研究对象,构造了一个相对简单的拓展系统,并利用同伦方法来求解该系统,所得的系统孤立解即为动态电压稳定的Hopf分岔点,也就是动态电压稳定的临界点.可以有效克服直接法对初值要求比较严格的缺点,同时利用相对简单的拓展系统来求解,在一定程度上减少了计算量.最后利用一个简化的电力系统动态模型进行验证.     

二面体群上的Hopf Ore扩张及其代数结构

主要研究了二面体群群代数的Ore扩张问题．利甩二面体群群代数上的1-余循环的不同分类,明确给出了在奇数和偶数两种情形下,二面体群群代数的Hopf Ore扩张的代数关系及其Hopf代数结构．     

有扭仿射李代数赋值模的某些性质

设g为有限维复单李代数,g^^[σ]为对应的有扭仿射李代数,U1,…,U,为不可约g-模,z1,…,zr为互不相同的非零复数．利用生成函数的方法证明赋值模U1（z1）×…Ur（zr）为g^^[σ]-模范畴E中不可约模并证明其同构定理．