Inter-cell spectrum efficiency improvement technology

Improvement in inter-cell spectrum efficiency is a valuable research topic in mobile communication system, which affects cell edge user experience especially. According to current research results, there are three methods to deal with inter-cell interference to improve inter-cell spectrum efficiency, including inter-cell interference randomization, inter-cell interference cancellation and inter-cell interference coordination. This paper analyzes three important inter-cell spectrum efficiency improvement technologies, soft frequency reuse (SFR), uplink power control, and downlink coordinated multi-point transmission/reception (CoMP), and relative research progress.     

UPLC-MS-Based Metabolomic Study of Streptomyces Strain HCCB10043 Under Different pH Conditions Reveals Important Pathways Affecting the Biosynthesis of A21978C Compounds

The A21978C family of compounds includes precursors of daptomycin, an important antibiotic for the treatment of diseases infected by Gram-positive resistant bacteria. Focusing on these valuable compounds, the differences in metabolites obtained with or without pH control in their producing strain Streptomyces parvus HCCB10043 were investigated by comparative metabolomics analysis based on UPLC-TOF-MS technology. According to principal component analysis, there were fourteen biomarker compounds selected under the two pH culture conditions. The ten known compounds were divided into two types: a glycoside family participating in the primary metabolism (daidzein, glycitein, genistein, and soyasaponin Bb) and a peptide family of secondary metabolites (valistatin, bestatin, 3-amino-2-hydroxy-4-phenylbutanoylvalylisoleucine, and arylomycins A2, A4, and A5). Through orthogonal partial least squares-discriminant analysis, three compounds, soyasaponin Bb and arylomycins A2 and A4 were identified as the most relevant compounds to A21978C1-3 production, the glycolytic pathway, and the NRPS synthesis pathway. The competitive relationship between arylomycin and A21978C was verified. These results have demonstrated the usefulness of the metabolomic strategy based on UPLC-MS in studying significant metabolic changes in actinomycetes. Moreover, this metabolomic strategy can provide new ideas and guidance for the regulation and improvement of secondary metabolites production.     

Broadband excitation pulses for high‐field solid‐state nuclear magnetic resonance spectroscopy

In nuclear magnetic resonance spectroscopy, experimental limits due to the radiofrequency transmitter and/or coil means that conventional radiofrequency pulses (“hard pulses”) are sometimes not sufficiently powerful to excite magnetization uniformly over a desired range of frequencies. Effects due to nonuniform excitation are most frequently encountered at high magnetic fields for nuclei with a large range of chemical shifts. Using optimal control theory, we have designed broadband excitation pulses that are suitable for solid‐state samples under magic‐angle‐spinning conditions. These pulses are easy to implement, robust to spinning frequency variations, and radiofrequency inhomogeneities, and only four times as long as a corresponding hard pulse. The utility of these pulses for uniformly exciting ¹³C nuclei is demonstrated on a 900 MHz (21.1 T) spectrometer. Copyright © 2012 John Wiley & Sons, Ltd.     

Light level control in birefringent fibres through thermal stress effects caused by the absorption of broadside incident light: a single-ended fibre-optic system

In this paper, light level control is demonstrated using optically induced thermal stress effects in a polarization-maintaining optical fibre. The controlling light beam is absorbed by a blackened segment of the fibre and produces local heating. Light control is demonstrated in the single-ended sensor configuration, which displays a response that cannot be explained from phase delays only, but requires the addition of the coupled mode theory.     

高斯光束在任意分布的径向梯度折射率介质中传输的计算方法

根据弱波导近似,本文建立了处理高斯光束在任意分布的径向梯度折射率介质中传输的计算方法,并具体计算和讨论了高斯光束腰斑在沿径向呈抛物型分布的介质中随传输距离的变化情况,其数值结果与解析近似符合。     

多环架光电稳定系统及分析

提出一种多环架高精度光电稳定系统方案。通过对其进行运动学分析，并结合伺服控制原理，证明该方案优于常规的二环架光电稳定系统。     

Optical inspection by internal reflection and spatial filtering

Some optical techniques for surface inspection applications are described. Paper texture is analyzed by a frustrated-total-internal-reflection method followed by spatial filtering of the diffracted pattern. Fibre-optics and micro-lenses are used to obtain a rugged and flexible sensor. Similar sensors are used for defect monitoring of roughly-polished surfaces. The practical aspects of sensor manufacture, speckle and vignetting considerations are discussed.     

30GHz RF脉冲压缩器设计

 为得到脉宽150ns，功率超过100MW的30GHz微波脉冲，采用MSLED-II原理设计了30GHz RF-脉冲压缩器。H-Hybrid，TE₁₀0^口-TE₁₀^o模式转换器等器件都采用了新型设计，所有微波器件的设计充分考虑了高功率下的适用性，没有容易引起打火的调谐杆、容性膜片等部件。在微波器件的设计中用HFSS软件进行了详尽的模拟。加工并测试了H-Hybrid，且用在CERN的RF脉冲展宽器上。     

单模光纤波导模的傍轴传输特性

将LP01模表示成用拉盖尔-高斯模线性叠加的形式,利用柯林斯公式推导出单模光纤波导模通过傍轴ABCD光学系统的解析传输公式。用所得的解析公式对LP01模在自由空间的传输和聚焦特性作了研究,并和高斯基模进行了比较。数值计算结果表明,用高斯基模描述LP01模会产生一定误差。LP01模经过透镜聚焦后存在焦移,且焦移随着菲涅尔数传输特性的减小而增大。选择合适的菲涅尔数聚焦后,LP01模会出现长焦深,这是与聚焦的高斯模所不同的。