声色俱“丽”——海尔V6200手机

2004年对手机市场而言是一个多事之秋．诺基亚（NOKIA)公司和索尼爱立售(Sony Ericsson)公司率先进入了百万像素拍照手机的阵营．三星(SAMSUNG)和摩托罗拉(MOTOROLA）公司也在手机的音效方面作了不小的努力，并推出了使用双扬声器设计的手机，这些具有创新理念的产品在手机市场上掀起了不小的波澜．榜样的力量是无穷的．海尔公司推出的这款V6200手机兼具百万像素和双扬声器的特点．此次更是来势汹汹。     

厚积薄发 20款新品闪耀波导

进入2005年，手机产业的发展日新月异，新技术、新应用层出不穷。各路厂商为了在市场上抢得先机，纷纷推出让人眼花缭乱的新产品。6月7日，国产手机领军品牌波导发动了夏季的新一轮攻势。一举推出了20款新品。其中不乏亮点之作。     

三星SGH-D880双卡双待手机 时尚双卡机

三星其实很早就推出过双卡手机，当年中国联通要推出双模机来解决G网和C网共存的问题时，三星就很快推出了一款双模机，不过那时的双模机只能有一个手机卡处于在网状态，实际上就是双卡切换。后来，就有了G/C双网双待手机，实现了两个手机卡同时在网。在此基础上，适应市场的需要，厂商又推出了G网双卡双待手机。三星SGH-D880就是这样一款手机。[编者按]     

A New High Efficiency Multiwave Cerenkov Generator Operating at Low Magnetic Field

With a resonant cavity inserted between the second slow-wave-structure section and the tapered wavegulde, a new structure of the multlwave Cerenkov generator (MWCG) operating at low guiding magnetic field is proposed to produce high efficiency and high power microwave. Some features and potential advantages of the proposed device are analysed. The 2.5-dimensional partlcle-in-cell simulation is employed to verify the initial expectation.The results show that, with the use of an electron beam of 640keV and 8.4kA guided by the magnetic lield of 0.6 T, a stable and monochromatic X-band microwave output of 4 GW in peak power is achieved, and the average efficiency is over 30%.     

抢先推出高端家用产品 EMC借新业务反噬中小企业

北京大山子艺术区中的798工厂,这个南众多低矮平房或小角楼组成的不起眼地方,却作为当下北京城艺术与时尚的地标性建筑群而享誉海内外.2008年4月2日,EMC选择这里作为它首款时尚存储产品的亮相地,可谓用心良苦.     

Musical Fidelity Tri—Vista 21 DAC数模转换器

Musical Fidelity(音乐传真)顶级的Tri—Vista系列产品线中的品种越来越齐全了，除了Tri—Vista双单声道综合扩大机、Tri-Vista SACD唱盘之外，现在又多了一位新成员：Tri-Vista 2I DAC数模转换器。该机使用24bit Delta—Sigma数据流工作方式，采用双差动架构，具备8倍超取样，可切换96／192kHz两种工作模式，并具备RCA同轴与光纤两种输入介面。     

Analysis and Simulation of S-shaped Waveguide in Silicon-on-insulator

The simulation and analysis of S-shaped waveguide bend are presented.Bend radius larger than 30 mm assures less than 0.5 dB radiation loss for a 4-μm-wide silicon-on-insulator waveguide bend with 2-μm etch depth.Intersection angle greater than 20° provides negligible crosstalk (<-30 dB) and very low insertion loss.Any reduction in bend radius and intersection angle is at the cost of the degradation of characteristics of bent waveguide and intersecting waveguide, respectively.     

Experimental Research on Erbium-doped Superfluorescent Fiber Source

The effects of the variations in fiber length, fiber mirror reflectance on efficiency and output power are experimentally investigated for erbium-doped double pass backward superfluorescent fiber sources (SFSs). The influence of fiber length on mean wavelength stability (MWS) has also been demonstrated. By incorporating a short section of un-pumped erbium-doped fiber (EDF) at the output port, the pump power dependent on MWS becomes independent of pumped EDF length. This is a novel phenomenon that hasn‘t been reported up to now,and should be helpful to SFS fabrication and theory analysis. By using a fiber Michelson interferometer as spectrum slicing component,a multi-wavelength fiber source (MWFS) with ～20 channels (from 1542nm to 1559nm) is got. The MWFS has a channel spacing of ～0. 8 nm which satisfies ITUstandard. The intensity fluctuation among channels is less than 0.5dB,and the extinction ratio of all channels is above 14dB. This kind of MWFS should be useful to wavelength division multiplexing systems.     

障碍拟阵图

Let G be a simple graph and T={S :S is extreme in G}. If M(V(G), T) is a matroid, then G is called an extreme matroid graph. In this paper, we study the properties of extreme matroid graph.