移动宽带互联网热点业务及商业模式浅析

综述移动宽带互联网正在发生的变化,对LBS、应用商店及UGC所影响的业务和热点商业模式进行了介绍和分析。     

一款灌入/拉出3A电流跨导驱动快速瞬态响应低漏失稳压器

本文设计了一款可以灌入(sink)和拉出(source)3A电流,低电源、低功耗的CMOS低漏失电压线性稳压器。采用电流镜像结Gm(跨导)驱动的LDO架构可以获得高稳定性和快速负载瞬态响应。基于UMC 0.5um标准CMOS工艺投片验证,芯片面积为1.0mm2。空载时该LDO静态电流为220uA,最大带载3A。测试表明,使用30uF陶瓷电容,在-1.8A到 1.8A 0.1us负载跳变时,该LDO可以在低于2us的时间达到稳态,且过冲小于1mV。     

A 0.13μm CMOS Δ ∑ fractional-N frequency synthesizer for WLAN transceivers

A fractional-N frequency synthesizer fabricated in a 0.13μm CMOS technology is presented for the application of IEEE 802.11 b/g wireless local area network(WLAN) transceivers.A monolithic LC voltage controlled oscillator(VCO) is implemented with an on-chip symmetric inductor.The fractional-TV frequency divider consists of a pulse swallow frequency divider and a 3rd-order multistage noise shaping(MASH)△Σmodulator with noise-shaped dithering techniques.Measurement results show that in all channels,phase noise of the synthesizer achieves -93 dBc/Hz and -118 dBc/Hz in band and out of band respectively with a phase-frequency detector (PFD) frequency of 20 MHz and a loop bandwidth of 100 kHz.The integrated RMS phase error is no more than 0.8°.The proposed synthesizer consumes 8.4 mW from a 1.2 V supply and occupies an area of 0.86 mm~2.     

LED静电损伤在老化过程中的变化趋势

针对发光二极管(LED)的可靠性问题,将抗静电测试与高温老化实验结合,将蓝绿色发光材料制成的二极管分组,测试其经过老化过程后的光色参数变化。实验数据表明,蓝绿色LED裸片与封装样品老化过程中的衰减趋势有一定差异,老化程度与封装材料和发光材料的搭配方式有关。对于未被静电损伤的芯片,经过老化过程后,并没有出现静电损伤被放大导致功能性失效的现象,静电对其参数衰减无明显影响,与单一的老化实验趋势相似。对于经过静电击打后出现异常,无法正常发光的芯片,高温老化实验产生了使其迅速损坏和复原的情况。     

基于荧光猝灭原理的硝基芳烃类爆炸物检测实验研究

基于荧光猝灭原理,以共轭荧光聚合物MEH-PPV为荧光指示剂,采用塑料光纤作为传感和传光元件进行硝基芳烃类爆炸物检测。实验采用探测荧光指示剂荧光寿命的方法进行爆炸物检测,荧光指示剂的荧光寿命利用相移法进行测量。测量了不同荧光指示剂浓度时系统对爆炸物检测的灵敏度,发现当MEH-PPV质量浓度为10 mg/L时,系统的灵敏度最高;研究了U形、双锥形、螺旋形塑料光纤传感头对系统灵敏度的影响,发现双锥形传感头的灵敏度最高;测试了荧光指示剂MEH-PPV的稳定性,实验表明光照会加快MEH-PPV的漂白速度。     

Characterization and Properties of Nickel Aluminide Nanocrystals in an Alumina Layer for Nonvolatile Memory Applications

Intermetallic nanocrystal memory devices with nickel aluminide nanocrystals in the electron-trapping layer and an alumina layer as the blocking layer were prepared on the surface of oxidized silicon substrates by sputter-coating of Ni and Al₂O₃ in sequence, followed by an annealing procedure. Several aluminide nanocrystal memory devices are reported. The effect of annealing at 900°C on the memory properties was investigated. Intermetallic nanocrystals were identified by high-resolution transmission electron microscopy and x-ray photoelectron spectroscopy as Ni₂Al₃ with sizes of 15–20 nm. The results showed that a sixfold increase (0.37 V to 2.34 V) in the memory window could be achieved after annealing for the optimal time of 3 min.     

A reproducible and high-throughput HPLC/MS method to separate sarcosine from α- and β-alanine and to quantify sarcosine in human serum and urine

While sarcosine was recently identified as a potential urine biomarker for prostate cancer, further studies have cast doubt on its utility to diagnose this condition. The inconsistent results may be due to the fact that alanine and sarcosine coelute on an HPLC reversed-phase column and the mass spectrometer cannot differentiate between the two isomers, since the same parent/product ions are generally used to measure them. In this study, we developed a high-throughput liquid chromatography-mass spectrometry (LC-MS) method that resolves sarcosine from alanine isomers, allowing its accurate quantification in human serum and urine. Assay reproducibility was determined using the coefficient of variation (CV) and intraclass correlation coefficient (ICC) in serum aliquots from 10 subjects and urine aliquots from 20 subjects across multiple analytic runs. Paired serum/urine samples from 42 subjects were used to evaluate sarcosine serum/urine correlation. Both urine and serum assays gave high sensitivity (limit of quantitation of 5 ng/mL) and reproducibility (serum assay, intra- and interassay CVs < 3% and ICCs > 99%; urine assay, intra-assay CV = 7.7% and ICC = 98.2% and interassay CV = 12.3% and ICC = 94.2%). In conclusion, this high-throughput LC-MS method is able to resolve sarcosine from α- and β-alanine and is useful for quantifying sarcosine in serum and urine samples.     

Improving deuterated potassium dihydrogen phosphate's electro-optical Q-switched characteristics by adding a pair of auxiliary electrodes

Deuterated potassium dihydrogen phosphate (DKDP) crystal is one of the most commonly used electro-optical (EO) Q-switch materials. A traditional DKDP EO Q-switch in the Pockels cell has a pair of electrodes, resulting in a nonuniform electric potential along the radial direction. Theoretical analysis and calculation show the radial nonuniform electric potential of DKDP crystals can be improved by adding a pair of auxiliary electrodes. Meanwhile, the experimental results demonstrate that the Q-switched laser characteristics are greatly improved with auxiliary electrodes added to DKDP crystal.     

Fabrication and characterization of Fe-Ni alloy/nickel ferrite composite nanofibers by electrospinning and partial reduction

A novel synthetic process has been developed to fabricate the magnetic alloy/spinel ferrite composite nanofibers. By employing the electrospinning technique and subsequent partial reduction, Fe-Ni alloy/nickel ferrite composite nanofibers with an average diameter of around 170 nm were successfully prepared. The synthesized composite nanofibers consist of the face centered cubic and body centered cubic phases of Fe-Ni alloy and the spinel phase of nickel ferrite, and have novel magnetic properties with much enhanced coercivity and saturation magnetization as compared with the pristine nickel ferrite nanofibers.     

山岭隧道穿越冲沟段施工风险分析与控制措施

以湖南省炎汝高速公路梅子山隧道为依托,根据冲沟段的地形地质条件,通过数值模拟研究浅埋偏压和拱部出露两种情况的施工力学行为,辨识施工中存在的不利因素,进行施工风险分析,提出隧道穿越冲沟段施工存在塌方、大变形、渗漏水、边仰坡失稳等风险事件,并有针对性地提出风险控制措施.结合现场施工与监测情况,讨论现场实施效果,洞内外变形正...