A PVT Tolerant 10 to 500 MHz All-Digital Phase-Locked Loop With Coupled TDC and DCO

An all-digital phase-locked loop (ADPLL) with all components working with time interval or period signals is demonstrated. The ADPLL consists mainly of a free-running ring oscillator (FRO), a time to digital converter (TDC), a digitally controlled oscillator (DCO), a digital divider and a digital loop filter. In the proposed architecture, the TDC and DCO have an equal time resolution from the common FRO. The digital divider keeps the loop gain constant when the frequency multiplication factor changes. As a result, the ADPLL is inherently stable regardless of the variations of the process, supply voltage and temperature (PVT). The ADPLL is fabricated in 0.13 $mu$m CMOS process. Measurement results show that it works well over wide operation conditions, with the input frequencies ranging from 37.5 KHz to 25 MHz, frequency multiplication factors from 10 to 255, output frequencies from 10 MHz to 500 MHz, and supply voltages from 0.6 V to 1.6 V.      

基于LABVIEW的光收发模组的测试平台及测试分析

文章以光发射组件TOSA和光接收组件ROSA为主要硬件,LABVIEW7.0为软件开发测试平台,对已组装好的光收发模组的性能进行测试,并分析不同温度下的测试眼图和数据结果,完成测试任务。最后对测试中存在的问题进行了总结和展望。     

白光LED可见光通信及其关键技术研究

LED照明具有节能、可靠、使用寿命长等特点,被认为是下一代主流照明技术。基于LED比荧光灯和白炽灯切换速度快的特性,用室内照明的白光LED光源作为通信基站进行信息无线传输的技术,就是现在国内外研究的热点技术-可见光通信技术。文章简要介绍了白光LED可见光无线通信技术在的研究现状,分析了它的关键技术,并从应用角度出发阐述了LED可见光无线通信技术的发展趋势。     

Analysis of ochratoxin A and ochratoxin B in traditional Chinese medicines by ultra-high-performance liquid chromatography–tandem mass spectrometry using [C20]-ochratoxin A as an internal standard

The paper reported a reliable analytical method for simultaneous determination of ochratoxin A (OTA) and ochratoxin B (OTB) in traditional Chinese medicines (TCMs) by ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS). The development of the method and investigations on the matrix influence were described in particular. The matrix effects were thereby minimized by using a reliable internal standard and a simple sample pretreatment. The established method was further validated by determining the linearity (R² ≥ 0.9990), average recovery (86.3–114.2%), sensitivity (limit of quantitation 0.03–0.19 ng mL⁻¹) and precision (relative standard deviation ≤ 13.1%). It was shown to be a suitable method for simultaneous determination of OTA and OTB in various TCMs. Finally, a total of 51 TCMs widely used in China were screened for OTA and OTB with the proposed method. The results showed that only 4 samples were contaminated with ochratoxins at low levels, indicating that it was low risk of ochratoxins to consumers who occasionally used TCMs.     

基于CSP工艺铽对Q345B再结晶的影响

以CSP工艺生产的Q345热轧钢板为研究对象,采用Gleeble-1500D热模拟实验机进行单、双道次轧制模拟实验,研究了稀土铽(Tb)对Q345B钢再结晶行为的影响.结果表明,稀土铽(Tb)能够明显地推迟Q345B钢的动态再结晶,使对应峰值应力在低温轧制时提高约10%,而对980℃以上时的峰值应力影响不明显;980℃以上轧制时,稀土铽(Tb)能够明显的降低间隔时间1.5 s时的静态软化率,但随间隔时间的增加,稀土铽(Tb)对静态软化率的影响减弱;加入稀土铽能够提高完全再结晶区温度,扩大部分再结晶区.     

快速凝固结合严酷变形镁合金丝的组织与性能

采用快速凝固(RS)技术制备了厚度小于80μm,具有细微组织的Mg-6.0%Zn-1.0%Y-0.6%Ce-0.6%Zr合金薄带,薄带经往复挤压(RE)4道次后,制成Φ35 mm坯料,坯料被进一步正挤压(EX)成Φ2.08 mm~Φ1.55 mm表面光洁的细丝。用SEM和STEM分析组织,用In-stron 5500R和弯曲试验装置测试机械性能。细丝基体晶粒直径为~1μm。一类强化相颗粒的平均直径为0.25μm,另一类50 nm。变形态细丝抗拉强度和延伸率分别为335 MPa和13%;经过300℃保温10 min,然后水冷处理,抗拉强度和延伸率分别为403 MPa和12%。材料的临界弯曲直径为~6.28 mm,压应力是细丝弯曲断裂的控制因素。     

双分子水和氨气催化CF3OH分子裂解的理论研究

利用G3和CBS-QB3的理论方法研究CF₃OH分子裂解成FCFO和HF,并考虑大气中双分子和氨气对CF₃OH分子裂解的催化作用. 理论计算表明：由于在G3的理论水平下,计算的能垒为188.52 kJ/mol,所以CF₃OH分子在大气条件下不可能发生单分子裂解;当氨气和双分子水被加入时,能垒都被降到25.08 kJ/mol,起了强的催化作用. 除此之外,应用过渡态理论对速率常数进行了计算,计算结果表明：氨气催化CF₃OH分子的速率常数是单分子和双分子催化CF₃OH分子裂解速率常数的10⁹和10⁵倍. 考虑到大气中这些物质的浓度,计算结果预测了氨气催化CF₃OH分子裂解在大气中起到重要的作用.     

Aqueous Synthesis of CdTe/CdSe Core/Shell Quantum Dots as pH-Sensitive Fluorescence Probe for the Determination of Ascorbic Acid

By controlling the reflux time and the quantity of the shell materials, different sizes of thioglycollic acid (TGA) modified CdTe/CdSe core/shell quantum dots were synthesized in aqueous solution. This type of QDs was used for sensitive and selective determination of ascorbic acid in commercial tablets. Under optimal conditions, a good linearity was observed between the relative fluorescence (FL) intensity and the concentration of ascorbic acid in the range of 4.0 to 64.0 μg/mL with a correlation coefficient of 0.9968. The limit of detection was 2.4 μg/mL. This method was applied to the determination of the ascorbic acid in Vitamin C tablets and Vitamin C Yinqiao pills, and satisfactory results were obtained.     

Fractional scanned carbon dioxide laser induces collagen remodelling in murine dermis

Resurfacing using a fractional CO₂ laser shows an important promise in the therapy on photoaged skin. The present study investigated that fractional CO₂ laser with a special sequential scanned manner induced the collagen remodelling in murine dermis. The results showed that laser resulted in the improvement of elasticity and histology in the murine dermis, meaning laser efficacy depends on both of the collagen formation and organization. We further investigated the relations between skin elasticity and type I, and type III collagen. These data demonstrated that laser could significantly lead to the collagen remodelling in murine dermis and induce neocollagenisis as a mode of resurfacing.     

《微分方程数值解》课程教学改革与实践

针对一般本科院校的教学实际,研讨《微分方程数值解》课程教学改革的一些体会,主要包括教学定位的确定、课程教学内容的优化、教学方法的改革以及教学手段的更新等问题.