HE-AAC V2编码原理及其应用

在保证优秀的音频质量下,提高音频编码的压缩效率是数字音频技术一直追求的目标,简单介绍目前最先进的音频编码HE-AAC V2的原理及应用,着重介绍其中用到的两种新技术频带复制(SBR)技术和参数立体声(PS)技术.     

Fracture and deformation properties of Ni-Fe superalloy in cryogenic high magnetic field environments

The present paper includes experimental and analytical data on the fracture properties of a nickel-iron superalloy, a ferromagnetic austenite, at 4 K in magnetic fields of 0 and 6 T. The tensile, notch tensile and small punch tests are employed. A finite element analysis is also performed to convert the experimentally measured load-displacement data into useful engineering information. To interpret the results we review the available theory of the influence of magnetic field on the stress intensity factor for a crack in ferromagnetic materials.     

Failure mode transition and energy dissipation in naturally occurring composites

The microstructural aspects of compressive inelastic deformation in balsa wood are investigated with emphasis on the failure mode transition and its effects on energy dissipation characteristics. The architectural features as well as the composite character of cell wall ultrastructure are discussed in a framework to understand the complex interrelationship between microstructure and macroscopic behavior in this extremely lightweight cellular biocomposite. Based on this discussion and experimental results, it is concluded that the biomimetic approach may prove to be a viable strategy in designing composite structures with high specific energy absorption capacity.     

基于ISP1581的USB2.0键盘数码管控制设备的固件编程

基于ISPl581的USB2．0键盘数码管控制设备的设计严格遵循USB2．0协议，体现了USB即插即用、易扩展、低干扰的特点，实现了主机和设备之间简单、快速、可靠的连接和通信。文章介绍了基于ISP1581的USB2．0键盘数码管控制设备的硬件、软件的设计方法。     

Staining of poly(ethylene terephthalate) by ruthenium tetroxide

The staining of poly(ethylene terephthalate) (PET) by ruthenium tetroxide (RuO₄) is used to obtain a contrast at the crystalline lamellar scale in transmission electron microscopy. This paper demonstrates the efficiency of this technique conducted in vapor phase on ultracut bulk samples. Advantages of this method against other contrast enhancing techniques and the parameters of staining are discussed. The depth of attack is measured and is shown to be limited by a crosslinking process. The chemical mechanisms are investigated by grazing infrared spectroscopy and involve the oxidation of the aliphatic moeities of PET.     

石墨炉原子吸收光谱(GFAAS)法测定石英玻璃中硼的研究

试样经氢氟酸分解，通过加入化学改进剂和多次注射浓缩样品及低温、长时间灰化的方法，在硝酸介质中用石墨炉原子吸收光谱法(GFAAS)测定石英玻璃中硼的含量。该方法解决了GFAAS法分析石英玻璃中硼灵敏度低和准确度低的问题。     

宽带业务发展与"撒手锏"、"产业链"的关系

重点论述下一代网络(NGN)、下一代宽带无线(NGBW)及3G演进中的宽带业务发展与“撒手锏”、“产业链”及持续创新与发展的关系。     

芴酮在合成功能高分子方面的应用

介绍了由芴酮合成的双酚芴在高分子材料方面的应用，尤其是在环氧树脂、聚碳酸酯、有机玻璃方面，与双酚A相比，用双酚芴改性的高分子材料具更高的耐热性及透明性。     

X-ray diffraction and Raman scattering in SbSI nanocrystals

Lattice structure and rod-like shaped SbSI nanocrystals obtained by ball milling with rod thickness down to 70 nm, as estimated from X-ray diffraction (XRD) and electron microscopy, is similar to that of the bulk crystals. The dependence of the grain size on the milling duration is discussed in view of the chain-like crystalline structure of SbSI. Possible factors, responsible for the observed Raman line broadening, are discussed, scattering by surface phonons being considered the predominant one.     

Gamma-irradiation-induced Ag/SiO2 composite films and their optical absorption properties

Small Ag particles or clusters dispersed mesoporous SiO₂ composite films were prepared by a new method: First the matrix SiO₂ films were prepared by sol-gel process combined with the dip-coating technique, then they were soaked in AgNO₃ solutions followed by irradiation of γ-ray at room temperature and in ambient pressure. The structures of these films were examined by X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), and optical absorption spectroscopy. It has been shown that the Ag particles grown within the porous SiO₂ films are very small, and they are isolated and dispersed from each other with very narrow size distributions. With increasing the soaking concentration and an additional annealing, an opposite peakshift effect of the surface plasmon resonance (SPR) was observed in the optical absorption measurements.