基于MPEG-4硬件解码的视频终端设计

以JADE Z228多媒体Soc芯片为核心，设计了一款适用于多媒体教学的MPEG-4视频终端．介绍了以Z228单处理器芯片实现MPEG-4解码输出的软、硬件设计过程以及与周边外设的接口方法，实现了VGA640×480分辨率、每秒30帧的MPEG-4视频解码输出的目标，使视频终端具有很高的性价比．     

New Sesquiterpenes from the Roots and Stems of Aristolochia Mollissima

Two new sesquiterpenes, madolins Y ( 1 ) and Z ( 2 ) were isolated from the dried roots and stems of Aristolochia mollissima, and their structures were determined by spectroscopic methods.     

Far from equilibrium steady states of 1D-Schrödinger–Poisson systems with quantum wells I

We describe the asymptotics of the steady states of the out-of-equilibrium Schrödinger–Poisson system, in the regime of quantum wells in a semiclassical island. After establishing uniform estimates on the nonlinearity, we show that the nonlinear steady states lie asymptotically in a finite-dimensional subspace of functions and that the involved spectral quantities are reduced to a finite number of so-called asymptotic resonant energies. The asymptotic finite dimensional nonlinear system is written in a general setting with only a partial information on its coefficients. After this first part, a complete derivation of the asymptotic nonlinear system will be done for some specific cases in a forthcoming article [V. Bonnaillie–Noël, F. Nier, M. Patel, Far from equilibrium steady states of 1D-Schrödinger–Poisson systems with quantum wells II, Prépublications IRMAR, 2007].     

基于CAN总线的数据采集节点的设计

CAN总线以其自身的技术特点和良好的性能在现代测控领域得到了广泛的应用,本文介绍了一种基于CAN总线的数据采集节点的设计方案,给出了系统总体设计和节点的基本结构,详细说明了以MSP430F449单片机、SJA1000为核心的节点的硬件及软件设计。可在CAN总线上挂载多个数据采集节点,解决了多个节点之间的通信问题。研究表明该方案具有硬件结构简单、成本低廉、采集精度高、抗干扰能力强等优点,实现了数据采集系统的网络化。     

Studies on nano suspensions of silver sol and redispersed nanocrystallite silver in aqueous and alcoholic media

Nanocrystallite silver and silver sol were prepared and characterized by UV-visible spectra, XRD, TEM and HRTEM. The crystallite silver is re-dispersed in two different media, namely, water and alcohol and sonicated before ultrasonic investigation. The silver sol was used as such. Three different models for the propagation of ultrasound through two phase media are compared in these three different types of nano suspensions. Effect of particle size and medium on ultrasonic velocity (U), compressibility (κ) impedance (Z) and viscous relaxation time (τ) is studied. The particle concentration range was 0.2-1 v/v. Density and viscosity of the dispersion and sol are measured at different particle volume fractions. Effective density and ultrasonic velocity are computed by Urick, Kuster and Toksöz and Urick and Ament models and compared with experimental velocities. Values of effective density obtained by using Urick and Urick and Ament equations closely agree with experimental results of density while Urick's equation prediction of velocity is in close agreement with the experimental velocities. This comes as a surprise in view of the large density difference between the medium and suspended particle and suggests the possibility of the balancing effect of the inertial and viscous forces operating in the suspension.     

Uniqueness of complete spacelike hypersurfaces via their higher order mean curvatures in a conformally stationary spacetime

We study complete noncompact spacelike hypersurfaces immersed into conformally stationary spacetimes, that is, Lorentzian manifolds endowed with a timelike conformal vector field V. In this setting, by using as main analytical tool a suitable maximum principle for complete noncompact Riemannian manifolds, we establish new characterizations of totally umbilical hypersurfaces in terms of their higher order mean curvatures. For instance, supposing an appropriated restriction on the norm of the tangential component of the vector field V, we are able to show that such hypersurfaces must be totally umbilical provided that either some of their higher order mean curvatures are linearly related or one of them is constant. Applications to the so‐called generalized Robertson‐Walker spacetimes are given. In particular, we extend to the Lorentzian context a classical result due to Jellett  29 .     

Peristatcally induced MHD slip flow in a porous medium due to a surface acoustic wavy wall

The influences of Hall current and slip condition on the MHD flow induced by sinusoidal peristaltic wavy wall in two dimensional viscous fluid through a porous medium for moderately large Reynolds number is considered on the basis of boundary layer theory in the case where the thickness of the boundary layer is larger than the amplitude of the wavy wall. Solutions are obtained in terms of a series expansion with respect to small amplitude by a regular perturbation method. Graphs of velocity components, both for the outer and inner flows for various values of the Reynolds number, slip parameter, Hall and magnetic parameters are drawn. The inner and outer solutions are matched by the matching process. An interesting application of the present results to mechanical engineering may be the possibility of the fluid transportation without an external pressure.     

自适应流量评估方法在IDC网络的应用

为了确保IDC网络的服务质量,往往需要了解IDC网络中各出口、各链路的网络拥塞、大规模网络攻击等流量信息并进行及时全量的数据监测和分析.本文提出了一种自适应流量评估方法,通过测量精度和存储资源两方面的调控,来优化现有的流量测量技术.     

Crystal structure and the role of cation group factor in the third‐order nonlinear optical properties of cadmium complexes constructed by 1,3‐dithiole‐2‐thione‐4,5‐dithiolato ligand

A cadmium complex bis(benzyltriethylammonium) bis(1,3‐dithiole‐2‐thione‐4,5‐dithiolato)‐cadmium(II) ((TEBA)₂[Cd(DMIT)₂]) has been synthesized and its crystal structure has been determined by means of X‐ray single‐crystal diffraction. The central cadmium(II) ion coordinates with two DMIT, which constructed a distorted tetrahedron environment. Its third‐order nonlinear optical properties have been studied using Z‐scan technique with 20 ps pulses at wavelength 1064 nm. Its third‐order nonlinear susceptibility χ⁽³⁾ value was determined to be 1.24 × 10⁻¹⁹ m² V⁻², the figure of merit, χ⁽³⁾/α₀, was estimated to be 2.64 × 10⁻²⁰ m³ V⁻². Copyright © 2011 John Wiley & Sons, Ltd.     

Verticillane‐Type Diterpenoids and an Eudesmanolide‐Type Sesquiterpene from the Formosan Soft Coral Cespitularia hypotentaculata

Four new diterpenes, cespihypotins W–Z ( 1 – 4 ), having the verticillane skeleton and characterized by an α,β‐unsaturated γ‐hydroxycyclopentanone moiety, and a new eudesmanolide‐type sesquiterpene, cespilactam A ( 5 ), containing an α,β‐unsaturated γ‐lactam residue, were isolated from the AcOEt‐soluble fraction of the Taiwanese soft coral Cespitularia hypotentaculata. The structure and relative configuration of these metabolites was elucidated through extensive interpretation of MS, COSY, HSQC, HMBC, and NOESY experiments and by comparison of their NMR data with those of related compounds.