Multiple delay-dependent guaranteed cost control for uncertain switched random nonlinear systems against intermittent sensor and actuator faults

In this paper, guaranteed cost control is investigated for switched random nonlinear systems against multiple state delays, model uncertainties, intermittent sensor and actuator faults. Other factors containing nonlinear dynamics, external disturbances as well as measurement noise are also considered. This is the first try to realize guaranteed cost control for uncertain switched random nonlinear systems against multiple time delays. In practice, color noise is more common than white noise in some specific situations. Thus, this paper considers random systems with color noise. In contrast to the previous study works, the suggested system can be applied to a wider range. First, a dynamic full-order output feedback controller is established to make the system stable. And an entire closed-loop system is got to achieve guaranteed cost control. Then, the multiple delay-dependent sufficient conditions are acquired through the piecewise Lyapunov function in the framework of linear matrix inequalities (LMIs). In the meantime, controller gain matrices are obtained. At last, two simulation examples are presented to verify the availability of the suggested approach.     

Tsallis non-extensive statistics,intermittent turbulence,SOC and chaos in the solar plasma. Part two: Solar flares dynamics

In this study which is the continuation of the first part (Pavlos et al. 2012) [1], the nonlinear analysis of the solar flares index is embedded in the non-extensive statistical theory of Tsallis (1988) [3]. The q$q$-triplet of Tsallis, as well as the correlation dimension and the Lyapunov exponent spectrum were estimated for the singular value decomposition (SVD) components of the solar flares timeseries. Also the multifractal scaling exponent spectrum f(a)$f\left(a\right)$, the generalized Renyi dimension spectrum D(q)$D\left(q\right)$ and the spectrum J(p)$J\left(p\right)$ of the structure function exponents were estimated experimentally and theoretically by using theq$q$-entropy principle included in Tsallis non-extensive statistical theory, following Arimitsu and Arimitsu (2000) [25]. Our analysis showed clearly the following: (a) a phase transition process in the solar flare dynamics from a high dimensional non-Gaussian self-organized critical (SOC) state to a low dimensional also non-Gaussian chaotic state, (b) strong intermittent solar corona turbulence and an anomalous (multifractal) diffusion solar corona process, which is strengthened as the solar corona dynamics makes a phase transition to low dimensional chaos, (c) faithful agreement of Tsallis non-equilibrium statistical theory with the experimental estimations of the functions: (i) non-Gaussian probability distribution function P(x)$P\left(x\right)$, (ii) f(a)$f\left(a\right)$ and D(q)$D\left(q\right)$, and (iii) J(p)$J\left(p\right)$ for the solar flares timeseries and its underlying non-equilibrium solar dynamics, and (d) the solar flare dynamical profile is revealed similar to the dynamical profile of the solar corona zone as far as the phase transition process from self-organized criticality (SOC) to chaos state. However the solar low corona (solar flare) dynamical characteristics can be clearly discriminated from the dynamical characteristics of the solar convection zone.     

Novel electron holes of Gaussian type due to second order,non-perturbative electron trapping and the general loss of identifiability of hole structures in experiments

A second order non-perturbative trapping scenario is employed to show the existence of a new Gaussian type of solitary electron holes. Use is thereby made of Schamel's pseudo-potential method, the only method that can guarantee the completeness of an equilibrium solution of the Vlasov-Poisson system in addition to its existence. The new potential is of the form $e^{-X{(x)}^2}$ where $X(x)=sinh(x)$ and is hence reminiscent of the Gaussian potential appearing in its “second generation”. The simultaneous presence of both trapping generations hence establishes a one-parametric continuum spectrum of solitary electron holes all of them being, through appropriate fitting, potential candidates for identifying structures in experimental observations and numerical simulations. Taking into account the possibility of many more trapping scenarios moreover, a unique identification of structures, the desired goal expressed in the current literature when interpreting structure formation, is therefore not achievable. Origin of this intrinsic ambiguity is the loss of mathematical stringency in the kinetic regime through chaos triggered by the ergodic particle trajectories in the resonant region of phase space in the single particle – coherent wave interaction process.     

Interaction between crack tip advancement and fluid flow in fracturing saturated porous media

We address stepwise crack tip advancement and pressure fluctuations, which have been observed in the field and experimentally in fracturing saturated porous media. Both fracturing due to mechanical loading and pressure driven fracture are considered. After presenting the experimental evidence and the different explanations for the phenomena put forward and mentioning briefly what has been obtained so far by published numerical and analytical methods we propose our explanation based on Biot’s theory. A short presentation of three methods able to simulate the observed phenomena namely the Central Force Model, the Standard Galerkin Finite Element Method SGFEM and extended finite element method XFEM follows. With the Central Force Model it is evidenced that already dry geomaterials break in an intermittent fashion and that the presence of a fluid affects the behavior more or less depending on the loading and boundary conditions. Examples dealing both with hydraulic fracturing and mechanical loading are shown. The conditions needed to reproduce the observed phenomena with FE models at macroscopic level are evidenced. They appear to be the adoption of a crack tip advancement/time step algorithm which interferes the least possible with the three interacting velocities, namely the crack tip advancement velocity on one side, the seepage velocity of the fluid in the domain and from the crack (leak-off), and the fluid velocity within the crack on the other side. Further the crack tip advancement algorithm must allow for reproducing jumps observed in the experiments.     

Intermittent simulated moving bed chromatographic separation of (RS,RS)-2-(2,4-difluorophenyl)butane-1,2,3-triol

The pharmaceutically relevant compound (RS,RS)-2-(2,4-difluorophenyl)butane-1,2,3-triol, an important intermediate in the production of different antifungal drugs, is synthesized in racemic form. For further use in the laboratory the compound has to be separated into its pure enantiomers. This work describes the different steps required to set up a chiral separation using intermittent simulated moving bed chromatography (I-SMB). Furthermore, the effect of feed concentration on the choice of the operating conditions is presented in the frame of the triangle theory. The experiments are carried out at increasing total feed concentration ranging from 3 to 15 g/L. The results demonstrate that a successful I-SMB separation could be carried out thus separating 4.5 g of the racemic mixture and fulfilling the specified purity specification of 98% for both enantiomers.     

Synchronization of non-autonomous chaotic systems with time-varying delay via delayed feedback control

In this paper, we investigate the synchronization of non-autonomous chaotic systems with time-varying delay via delayed feedback control. Using a combination of Riccati differential equation approach, Lyapunov-Krasovskii functional, inequality techniques, some sufficient conditions for exponentially stability of the error system are formulated in form of a solution to the standard Riccati differential equation. The designed controller ensures that the synchronization of non-autonomous chaotic systems are proposed via delayed feedback control and intermittent linear state delayed feedback control. Numerical simulations are presented to illustrate the effectiveness of these synchronization criteria.     

交替微波加热法对制备氧还原催化剂性能的影响

详细研究了交替微波加热法制备多壁碳纳米管负载Pt催化剂(Pt/MWCNTs)的过程中交替微波加热(5s-on/5s-off)次数对催化剂性能的影响.X射线粉末衍射(XRD)结果表明,Pt的晶粒尺寸在开始的加热阶段基本上没有发生变化,但是随着加热次数的增多,Pt的晶粒尺寸逐步增大.采用循环伏安法和旋转圆盘电极技术考察了催化剂的电化学活性.结果显示,以5s-on/5s-off加热20次时,催化剂显示出最佳的催化活性;在0.5mol· L-1 H2SO4饱和氧水溶液中催化剂的氧还原起峰电位接近1.0 V(vs RHE).交替微波加热法简单经济,在大批量制备催化剂等纳米材料方面显示出较好的应用前景.     

Tsallis non-extensive statistics,intermittent turbulence,SOC and chaos in the solar plasma,Part one: Sunspot dynamics

In this study, the non-linear analysis of the sunspot index is embedded in the non-extensive statistical theory of Tsallis (1988, 2004, 2009) ,  and . The q$q$-triplet of Tsallis, as well as the correlation dimension and the Lyapunov exponent spectrum were estimated for the SVD components of the sunspot index timeseries. Also the multifractal scaling exponent spectrum f(a)$f\left(a\right)$, the generalized Renyi dimension spectrum D(q)$D\left(q\right)$ and the spectrum J(p)$J\left(p\right)$ of the structure function exponents were estimated experimentally and theoretically by using the q$q$-entropy principle included in Tsallis non-extensive statistical theory, following Arimitsu and Arimitsu (2001, 2000)  and . Our analysis showed clearly the following: (a) a phase transition process in the solar dynamics from high dimensional non-Gaussian SOC state to a low dimensional non-Gaussian chaotic state, (b) strong intermittent solar turbulence and anomalous (multifractal) diffusion solar process, which is strengthened as the solar dynamics makes a phase transition to low dimensional chaos in accordance to Ruzmaikin, Zeleny and Milovanov’s studies (Zelenyi and Milovanov (1991) [21]); Milovanov and Zelenyi (1993) [22]; Ruzmakin et al. (1996) [26]) (c) faithful agreement of Tsallis non-equilibrium statistical theory with the experimental estimations of (i) non-Gaussian probability distribution function P(x)$P\left(x\right)$, (ii) multifractal scaling exponent spectrum f(a)$f\left(a\right)$ and generalized Renyi dimension spectrum _Dq$D_q$, (iii) exponent spectrum J(p)$J\left(p\right)$ of the structure functions estimated for the sunspot index and its underlying non equilibrium solar dynamics.     

Tsallis statistics and magnetospheric self-organization

In this study we use Tsallis non-extensive statistics for a new understanding the magnetospheric dynamics and the magnetospheric self-organization during quiet and intensive superstorm periods. The _qsens$q_{sens}$, _qstat$q_{stat}$, and _qrel$q_{rel}$ indices set known as the Tsallis q$q$-triplet was estimated during both quiet and strongly active periods, as well as the correlation dimensions and Lyapunov exponents spectrum for magnetospheric bulk plasma flows data. The results obtained by our analysis clearly indicate the magnetospheric phase transition process from a high-dimensional quiet SOC state to a low-dimensional global chaotic state when superstorm events are developed. During such a phase transition process the non-extensive statistical character of the magnetospheric plasma is strengthened as the values of the q$q$-triplet indices changes obtaining higher values than their values during the quiet periods.     

Exponential synchronization of complex delayed dynamical networks via pinning periodically intermittent control

The problem of synchronization for a class of complex delayed dynamical networks via pinning periodically intermittent control is considered in this Letter. Some novel and useful exponential synchronization criteria are obtained by utilizing the methods which are different from the techniques employed in the existing works, and the derived results are less conservative. Especially, the traditional assumptions on control width and time delays are released in our results. Moreover, a pinning scheme deciding what nodes should be chosen as pinned candidates and how many nodes are needed to be pinned for a fixed coupling strength is provided. A Barabási-Albert network example is finally given to illustrate the effectiveness of the theoretical results.