Infinite horizon H_2/H_\infty optimal control for discrete-time Markov jump systems with (x,u,v)-dependent noise

In this paper, an infinite horizon $H_2/H_\infty $ control problem is addressed for a broad class of discrete-time Markov jump systems with ( $x,u,v$ )-dependent noises. First of all, under the condition of exact detectability, the stochastic Popov–Belevich–Hautus (PBH) criterion is utilized to establish an extended Lyapunov theorem for a generalized Lyapunov equation. Further, a necessary and sufficient condition is presented for the existence of state-feedback $H_2/H_\infty $ optimal controller on the basis of two coupled matrix Riccati equations, which may be solved by a backward iterative algorithm. A numerical example with simulations is supplied to illustrate the proposed theoretical results.     

Quadratic nonlinear response to 1.56-μm continuous wave laser in semi-insulating GaAs

The nonlinear photoresponse to a 1.56μm infrared continuous wave laser in semi-insulating （SI） galliu- marsenide （GaAs） is examined. The double-frequency absorption （DFA） is responsible for the nonlinear photoresponse based on the quadratic dependence of the photocurrent separately on the coupled optical power and bias voltage. The electric field-induced DFA remarkably affects the native DFA in SI GaAs. The surface electric field or the surface band-bending of SI GaAs significantly affects the magnitude variation of the Dhotocurrent and dark current     

Spin gapless armchair graphene nanoribbons under magnetic field and uniaxial strain

Using Green＇s function method, we investigate the spin transport properties of armchair graphene nanoribbons （AG- NRs） under magnetic field and uniaxial strain. Our results show that it is very difficult to transform narrow AGNRs directly from semiconductor to spin gapless semiconductors （SGS） by applying magnetic fields. However, as a uniaxial strain is exerted on the nanoribbons, the AGNRs can transform to SGS by a small magnetic field. The combination mode be- tween magnetic field and uniaxial strain displays a nonmonotonic arch-pattern relationship. In addition, we find that the combination mode is associated with the widths of nanoribbons, which exhibits group behaviors.     

Photoinduced charge injection in the metal/organic interface studied by transient photovoltage measurements with bias

Transient photovoltage of ITO/organic/Al cells is studied under different bias polarities and voltages.It is found that for an ITO/NPB/Al cell,light incidence on the Al side induces more bias-dependent transient photovoltage variation when the photovoltage is positive than when it is negative.However,for an ITO/C60 /Al cell,the variation characteristics of transient photovoltage is reversed.These results support the previously proposed mechanism that Al could inject charges into the organic layer upon photon excitation,indicating that the absorption of electrode can also contribute to photovoltaic effect.     

Optimality of a Class of Entanglement Witnesses for 3⊗3 Systems

Let $\varPhi_{t,\pi}: M_{3}({\mathbb{C}}) \rightarrow M_{3}({\mathbb{C}})$ be a linear map defined by $\varPhi_{t,\pi}(A)=(3-t)\*\sum_{i=1}^{3}E_{ii}AE_{ii}+t\sum_{i=1}^{3}E_{i,\pi (i)}AE_{i,\pi(i)}^{\dag}-A$ , where 0≤t≤3 and π is a permutation of (1,2,3). We show that the Hermitian matrix $W_{\varPhi_{t,\pi}}$ induced by Φ _t,π is an optimal entanglement witness if and only if t=1 and π is cyclic.     

Global Regularity of the 3D Axi-Symmetric Navier–Stokes Equations with Anisotropic Data

In this paper, we study the 3D axisymmetric Navier–Stokes equations with swirl. We prove the global regularity of the 3D Navier–Stokes equations for a family of large anisotropic initial data. Moreover, we obtain a global bound of the solution in terms of its initial data in some L ^p norm. Our results also reveal some interesting dynamic growth behavior of the solution due to the interaction between the angular velocity and the angular vorticity fields.     

Permanence and periodic solutions for a class of delay Nicholson’s blowflies models

This paper covers the dynamic behaviors for a class of Nicholson’s blowflies models with a nonlinear density-dependent mortality term. By using inequality analyze technique and coincidence degree theory, some sufficient conditions are determined that guarantee the permanence of the model and the existence of positive periodic solutions. Moreover, we give an example to illustrate our main results.     

Distance unimodular equivalence of graphs

Let G be a connected graph and D(G) be its distance matrix. In this article, the Smith normal forms of the integer matrices D(G) are determined for trees, wheels, cycles, complements of cycles and are reduced for complete multipartite graphs.     

Consistency analysis of the spectrum and prosody within a syllable for Mandarin speech

This work presents a study of Mandarin speech focusing on consistency analysis of the spectrum and prosody within syllables. Identified as a result of inspection of the human pronunciation process, this consistency can be interpreted as a high correlation between the warping curves of the spectrum and the prosody intra a syllable. The consistency analysis consisted of three steps. First, the hidden Markov model algorithm was used to decode the hidden Markov model‐state sequences within a syllable, while at the same time dividing them into three segments. Second, based on a designated syllable, the vector quantization (VQ) with the Linde–Buzo–Gray algorithm was employed to train the VQ codebooks of the prosodic vector of each segment. Third, the prosodic vector of each segment was encoded as an index using the VQ codebooks, and then, to analyze the consistency, the probability of each possible path was evaluated as a prerequisite. Finally, two syllables were used as examples to verify the consistency property found in the experiments. It is demonstrated experimentally that there is definitely consistency in the case where the syllable is located in exactly the same word. These results offer a research direction in that the warping process between the spectrum and the prosody intra a syllable must be considered in text‐to‐speech systems to improve the synthesized speech quality. Copyright © 2013 John Wiley & Sons, Ltd.