Almost periodic and pseudo-almost periodic solutions to fractional differential and integro-differential equations

We study the existence of almost periodic (resp., pseudo-almost periodic) mild solutions for fractional differential and integro-differential equations in the case when the forcing term belongs to the class of Stepanov almost (resp., Stepanov-like pseudo-almost) periodic functions.     

Dynamics analysis of a delayed viral infection model with immune impairment

In this paper, the dynamical behavior of a delayed viral infection model with immune impairment is studied. It is shown that if the basic reproductive number of the virus is less than one, then the uninfected equilibrium is globally asymptotically stable for both ODE and DDE model. And the effect of time delay on stabilities of the equilibria of the DDE model has been studied. By theoretical analysis and numerical simulations, we show that the immune impairment rate has no effect on the stability of the ODE model, while it has a dramatic effect on the infected equilibrium of the DDE model.     

Is There an Effect of Dysphonic Teachers' Voices on Children's Processing of Spoken Language?

There is a vast body of literature on the causes, prevalence, implications, and issues of vocal dysfunction in teachers. However, the educational effect of teacher vocal impairment is largely unknown. The purpose of this study was to investigate the effect of impaired voice quality on children's processing of spoken language. One hundred and seven children (age range, 9.2 to 10.6, mean 9.8, SD 3.76 months) listened to three video passages, one read in a control voice, one in a mild dysphonic voice, and one in a severe dysphonic voice. After each video passage, children were asked to answer six questions, with multiple-choice answers. The results indicated that children's perceptions of speech across the three voice qualities differed, regardless of gender, IQ, and school attended. Performance in the control voice passages was better than performance in the mild and severe dysphonic voice passages. No difference was found between performance in the mild and severe dysphonic voice passages, highlighting that any form of vocal impairment is detrimental to children's speech processing and is therefore likely to have a negative educational effect. These findings, in light of the high rate of vocal dysfunction in teachers, further support the implementation of specific voice care education for those in the teaching profession.     

Multimodal Interfaces for Cell Phones and Mobile Technology

By modeling users' natural spoken and multimodal communication patterns, more powerful and highly reliable interfaces can be designed that support emerging mobile technology. In this paper, we highlight three different examples of research that is advancing state-of-the-art mobile technology. The first is the development of fusion-based multimodal systems, such as ones that combine speech and pen or touch input, which are substantially improving the robustness and stability of system recognition. The second is modeling of multimodal communication patterns to establish open-microphone engagement techniques that work in challenging multi-person mobile settings. The third is new approaches to adaptive processing, which are able to transparently guide user input to match system processing capabilities. All three research directions are contributing to the design of more reliable, usable, and commercially promising mobile systems of the future.     

Informational acquisition and cognitive models

Life forms must organize information into cognitive models reflecting the outside environment, and in a complex and changing environment a life form must constantly select and organize this mass of information to avoid slipping into a chaotic cognitive state. The task of developing and maintaining adaptive cognitive models can be understood through two processes, crucial to regulating the interconnections between environmental elements. The inclusion and exclusion of information follows a process designated by P and the process by which cognitive models change is designated by K. Higher order concepts are created by reducing the interconnections between elements to a minimal number to avoid cognitive chaos. © 2004 Wiley Periodicals, Inc. Complexity 9:31–37, 2004     

Global well-posedness and blow-up for the 2-D Patlak–Keller–Segel equation

In this paper, we prove that for every nonnegative initial data in $L^1({\mathbb{R}}^2)$, the Patlak–Keller–Segel equation is globally well-posed if and only if the total mass $M\le 8\pi$. Our proof is based on some monotonicity formulas of nonnegative mild solutions.     

认知无线电网络中提高传输层端到端吞吐率的跨层参数配置

在认知无线电网络中, 传输层端到端(TCP)吞吐率是衡量网络性能的重要指标. 前期相关研究大都具有以下两方面缺点: 第一, 大部分研究只考虑了协议底层参数来优化物理链路性能, 对传输层性能有所忽略; 第二, 目前的研究大都基于马尔可夫决策过程建模, 这需要网络具有完全知识, 使得这类模型的应用受到很大限制. 针对以上问题, 本文提出一种新的算法: 网络中每个节点通过联合配置物理层调制方式、发射功率、 链路层信道接入和TCP拥塞控制因子来找到传输层端到端近似最优吞吐率. 由于无线设备对环境感知存在误差, 本文将网络模型建模为部分可观测马尔可夫决策过程, 并将其转换成信念状态马尔可夫决策过程, 采用Q值迭代找到近似最优策略. 仿真分析表明, 提出的算法能在动态无线环境下以一定的误差限收敛于最优策略, 能在功率受限条件下, 有效提高传输层端到端吞吐率.     

Extrapolation spaces and controllability of impulsive semilinear functional differential inclusions with infinite delay in Fréchet spaces

In this article, we investigate some classes of semilinear impulsive functional differential inclusions with infinite delay. It is assumed that the linear part is possibly neither densely defined nor it satisfies the Hille–Yosida condition on a Banach space, namely the extrapolated space. Our approach is based on the theory of extrapolation spaces combined with a recent Frigon nonlinear alternative for multivalued admissible contractions in Fréchet spaces.     

Characterizations of proximinal,semichebychevian and chebychevian subspaces in real normed spaces

A simple model optimal control problem for continuous casting with state-space constraints is approximated, as usual, by a penalty method and by a numerical discretization of the nonlinear heat equation. The convergence of the approximate problems directly to the original problem is proven under a stability criterion linking the penalty parameter with the discretization parameters. For this purpose, known discretization error estimates for the Stefan problem are extended for the case of time varying boundary conditions.     

Numerical study of influence of molecular diffusion in the Mild combustion regime

In this paper, the importance of molecular diffusion versus turbulent transport in the moderate or intense low-oxygen dilution (Mild) combustion mode has been numerically studied. The experimental conditions of Dally et al. [Proc. Combust. Inst. 29 (2002) 1147–1154] were used for modelling. The EDC model was used to describe the turbulence–chemistry interaction. The DRM-22 reduced mechanism and the GRI 2.11 full mechanism were used to represent the chemical reactions of an H₂/methane jet flame. The importance of molecular diffusion for various O₂ levels, jet Reynolds numbers and H₂ fuel contents was investigated. Results show that the molecular diffusion in Mild combustion cannot be ignored in comparison with the turbulent transport. Also, the method of inclusion of molecular diffusion in combustion modelling has a considerable effect on the accuracy of numerical modelling of Mild combustion. By decreasing the jet Reynolds number, decreasing the oxygen concentration in the airflow or increasing H₂ in the fuel mixture, the influence of molecular diffusion on Mild combustion increases.