Strong stability of the mono-tubular heat exchanger equation with output feedback

We investigate asymptotic behavior of the C₀-semigroup T(t) associated with the mono-tubular heat exchanger equation with output feedback by a perturbation method. It is shown that T(t) is bounded if a constraint is satisfied by the parameters and the spatial distribution function. Further, applying the Arendt-Batty-Lyubich-Vu theorem, a criterion is established to judge strong stability of T(t).     

Espaces métriques rationnellement présentés et complexité, le cas de l'espace des fonctions réelles uniformément continues sur un intervalle compact

We define the notion of rational presentation of a complete metric space, in order to study metric spaces from the algorithmic complexity point of view. In this setting, we study some representations of the space C[0,1] of uniformly continuous real functions over [0,1] with the usual norm: ||f||_∞ = Sup{|f(x)|; 0x1}. This allows us to have a comparison of global kind between complexity notions attached to these presentations. In particular, we get a generalization of Hoover's results concerning the Weierstrass approximation theorem in polynomial time. We get also a generalization of previous results on analytic functions which are computable in polynomial time.     

竹红菌乙素对人红细胞膜蛋白荧光猝灭机理的研究

本文利用人红细胞膜蛋白内源荧光(主要指色氨酸),经加入不同的竹红菌乙素之后,引起了荧光猝灭现象,根据荧光猝灭原理分别从吸收光谱,荧光光谱,稳态变温实验和瞬态荧光等技术分析了上述的猝灭过程,实验证明:该猝灭是以动态碰撞过程为主要作用机理,据此作者提出了乙素可以用于生物膜体系的蛋白质荧光猝灭剂的理由。     

基于物联网与3G整合的电子商务应用资金流探析

文章在简要介绍物联网与3G网络的基础上,阐述了物联网与3G整合背景下电子商务资金流所具备的特点,进而论述了此背景下资金流的优化和作用,最后重点分析了整合背景下电子商务资金流的两个应用案例。     

Growth and characterization of Si doped vapor phase epitaxial GaAs for mesfet

This paper describes the Si-doping of GaAs that was grown using the AsCl₃:H₂:GaAs, Ga Chemical vapor deposition process. The doping sources were AsCl₃:SiCl₄ liquid solutions which proved to be highly reproducible for Si doping within the range, 1×1O¹⁶ to 2×10¹⁹ cm^?3. Incorporation of Si into the GaAs apparently occurs under near equilibrium conditions. This point is considered in detail and the consequences experimentally utilized to grow n, n+ bilayers using a single AsCl₃:SiCl₄ doping solution. Si impurity profiles based upon differential capacitance and SIMS data are presented. These can be very abrupt for n, n⁺ structures with order of magnitude changes occurring within 500 Å. For the 1×10₁₆ to 8×l0¹⁸ cm^?3 doped samples the mobilities at 78 and 298°K are comparable to the higher values reported for GaAs thin films grown by CVD. Power FET devices made from this material have demonstrated an output density of 0.86 watts/mm at 10 GHz.     

Helium gas permeability of montmorillonite/epoxy nanocomposites

Helium gas permeability of silicate clay (montmorillonite) particles/epoxy nanocomposites was examined. The incorporation of increasing amounts of montmorillonite particles reduced the helium gas permeability. Based on Fick’s law, gas permeation behavior of the nanocomposite was evaluated. With the increase of montmorillonite loading, gas diffusivity decreased, while gas solubility increased. Helium diffusion behavior is in agreement to the numerical results based on the Hatta–Taya–Eshelby theory. It has been revealed that dispersion of nanoscale platelets in polymer is effective in improving gas barrier property.     

Micro- and nano-scale deformation behavior of nylon 66-based binary and ternary nanocomposites

The primary aim of this paper is to provide an insight on the effect of the location of organoclay on the micro- and nano-scale deformation processes in melt-compounded nylon 66/organoclay/SEBS-g-MA ternary nanocomposites prepared by different blending sequences. In addition, the deformation processes of the ternary nanocomposites were compared to the binary nanocomposites (nylon 66/organoclay and nylon 66/SEBS-g-MA) and neat nylon 66. The incorporation of SEBS-g-MA particles toughened nylon 66 markedly; but the flexural modulus and strength were both reduced. Conversely, the use of organoclay increased the modulus but decreased the fracture toughness of nylon 66. Nylon 66/SEBS-g-MA/organoclay ternary nanocomposites exhibited balanced elastic stiffness and toughness. Stress-whitening studies of the fracture surfaces in terms of gray level were also performed and an attempt was made to correlate the optical reflectivity characteristics with fracture toughness. It was concluded that the capability of SEBS-g-MA particles to cavitate was decreased by the presence of organoclay in the SEBS-g-MA phase, resulting in reduced toughening efficiency. The best micro-structure for toughness and other mechanical properties is thus to maximize the amount of exfoliated organoclay in the nylon 66 matrix rather than to have it embedded in the finely dispersed SEBS-g-MA particles.     

基于ARM的广播发射机微控制器硬件系统设计

应用Samsung公司的S3C44B0X嵌入式芯片构建硬件平台,设计广播发射机微控制器。按照其在广播发射机监测控制系统中的控制特点,介绍和论述该微控制器的硬件结构。与传统的基于8/16位单片机构建的系统相比,由于S3C44B0X芯片内置多种实用外设可大大简化电路,从而提高了系统的可靠性,增强了系统抗干扰能力。     

G.729A+B语音编解码在新一代定点DSPs上的实现

文章介绍了ITU-TG．729A算法与ITU-TG．729B算法配合使用的语音编解码方案，并讨论了其在TI公司最新一代定点数字信号处理器(DSPs)TMS320C6416上实现的关键技术。G．729A是G.729编码器的简化版本，G．729B是带VAD(活动话音检测)的静音压缩算法。两者结合可以有效地降低码率，同时保持很好的合成语音质量。