用于太赫兹通信的双向全并行相位估计算法

在太赫兹通信的超宽带应用场景下,太赫兹载波是通过多次倍频实现,因而导致相噪严重恶化。基于太赫兹频率下的多极/零相位噪声模型,在传统的盲相位估计算法的基础上,提出了一种全并行化的相位估计算法。该算法通过在每个并行数据中插入导频,将导频相噪信息作为初始相位对并行数据进行相位扩展及旋转鉴相。借鉴传统盲相位估计算法的最佳相位估计值的判决选择思路,同时利用前一时刻导频和当前时刻导频,对当前并行数据从前后两个方向进行相位估计并对前后两个估计相位基于距离前后导频的位置进行加权求和以获得最佳相位估计信息。经过仿真验证,通过该算法后残余相噪在1 MHz和10 MHz处分别降低10 dBc/Hz和25 dBc/Hz。     

Determination of Acetonitrile Volume Fraction in Mobile Phase by HPLC

This paper reports the development and validation of an assay for the determination of acetonitrile in the recycled mobile phase using high performance liquid chromatography（HPLC）. The method is based on that the retention in reversed-phase liquid chromatography increases with decreasing concentration of organic phase in the mobile phase. The natural logarithm of the capacity ratio for a given solute is linearly related to the volume fraction of the organic modifier in the mobile phase. For dimethylphthalate and diethylphthalate, the linearity range is 30%--60%, and for biphenyl and terphenyl, the range is 60%--95%. Precision values（RSD） were both 〈1% and the accuracy（RE） was in the range of ±1%. The assay was successfully applied to the determination of acetonitrile concentration of recycled mobile phase after the distillation of the column eluent in our laboratory.     

Packed-Fiber Solid Phase-Extraction Coupled with HPLC-MS/MS for Rapid Determination of Lipid Oxidative Damage Biomarker 8-Iso-Prostaglandin F2α in Urine

The 8-iso-prostaglandin F_2α (8-iso-PGF_2α) biomarker is used as the gold standard for tracing lipid oxidative stress in vivo. The analysis of urinary 8-iso-PGF_2α is challenging when dealing with trace amounts of 8-iso-PGF_2α and the complexity of urine matrixes. A packed-fiber solid-phase extraction (PFSPE)–coupled with HPLC-MS/MS–method, based on polystyrene (PS)-electrospun nanofibers, was developed for the specific determination of 8-iso-PGF_2α in urine and compared with other newly developed LC-MS/MS methods. The method, which simultaneously processed 12 samples within 5 min on a self-made semi-automatic array solid-phase extraction processor, was the first to introduce PS-electrospun nanofibers as an adsorbent for the extraction of 8-iso-PGF_2α and was successfully applied to real urine samples. After optimizing the PFSPE conditions, good linearity in the range of 0.05–5 ng/mL with R² > 0.9996 and a satisfactory limit of detection of 0.015 ng/mL were obtained, with good intraday and interday precision (RSD < 10%) and recoveries of 95.3–103.8%. This feasible method is expected to be used for the batch quantitative analysis of urinary 8-iso-PGF_2α.     

A Video Coding Algorithm Based on Intraframe and Interframe Joint Prediction of Wavelet Coefficients

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In-Ga合金源汽相外延生长In_xGa_(1-x)As体系的热力学分析

本文采用独立组元法对In-Ga合金源汽相外延生长In_xGa_(1-x)As体系的平衡状态作了热力学计算和分析,所得结果对认识该体系外延生长的规律性及改进工艺条件有一定参考价值.     

Compositional, structural, optical and electrical characterization of CulnTe2 grown by the tellurization of stoichiometric Cu and in in the liquid phase

A new method to grow single crystals with stoichiometry close to 1:1:2 of CuInTe₂, an important member of the Cu-III-VI₂ family of semiconductors is described. This consists of tellurization in the liquid phase of stoichiometric Cu and In and later solidification under directional freezing. It is found from energy dispersive spectroscopy that the ingots obtained with the evaporation temperature (T_t) of Te at 590 and 635°C were very close to the ideal stoichiometry 1:1:2. Samples of all ingots obtained with T_t between 530 and 690°C, as studied by x-ray and differential thermal analysis, were of single phase having chalcopyrite structure and p-type conductivity. Optical and electrical characterization of different ingots were made. The acceptor ionization energy E_A and the density of states effective mass m _p ^* of the holes are estimated from the temperature dependence of the hole concentration p in samples of different ingots. m _p ^* = (0.78 ± 0.02) m_e agrees quite well with the reported value. From a combined analysis of the variation of E_A with p^1/3 and the knowledge of molecularity and valence stoichiometry of each sample, it is established that the shallow acceptor level observed in different samples with E_A (0) ⋍ 30 meV is due to V_In.     

利用相位和强度调制器产生高消光比超短光脉冲

提出了一种产生高消光比超短光脉冲的新方法.利用相位调制器调制连续光生成啾啁光,而后利用M-Z强度调制器的倍频调制抑制对压缩不利的啁啾部分的影响,再通过等效啁啾光纤光栅进行压缩产生光脉冲.理论和仿真结果表明,该方法可以很好地消除光脉冲的基底及减小旁辦,产生消光比大于30 dB、波形理想的光脉冲,具有很强的可实现性.最后利用实际制作的色散系数为-380 ps/nm的等效啁啾光纤光栅对该方法进行了实验验证,结果表明,在重复频率为2.5 GHz、相位调制系数为9时,可产生脉宽小于18 ps的高质量光脉冲.     

ROTATED BARNES-WALL LATTICE BASED VECTOR QUANTIZER AND ITS APPLICATION IN IMAGE-SEQUENCE CODING

A new scheme is presented to design a rotated Barnes-Wall lattice based vector quantizer(LVQ). The construction method of the LVQ and its fast quantizing algorithm are described at first. Then gain-shape lattice vector quantizer(GSLVQ) with LVQ as shape quantizer is discussed. Finally the GSLVQ is used in image-sequence coding and good experimental results are obtained.     

液晶投影电视中视频信号与显示模件接口电路的设计与研究

本文介绍了液晶投影电视的基本原理和光学系统,根据液晶显示模件的接口参数,设计了液晶投影电视的接口电路,对该电路的工作原理进行了分析和讨论。同时,对行同步相位调整电路进行了详细的电路设计和研究。     

Spiking patterns of a hippocampus model in electric fields

We develop a model of CA3 neurons embedded in a resistive array to mimic the effects of electric fields from a new perspective. Effects of DC and sinusoidal electric fields on firing patterns in CA3 neurons are investigated in this study. The firing patterns can be switched from no firing pattern to burst or from burst to fast periodic firing pattern with the increase of DC electric field intensity. It is also found that the firing activities are sensitive to the frequency and amplitude of the sinusoidal electric field. Different phase-locking states and chaotic firing regions are observed in the parameter space of frequency and amplitude. These findings are qualitatively in accordance with the results of relevant experimental and numerical studies. It is implied that the external or endogenous electric field can modulate the neural code in the brain. Furthermore, it is helpful to develop control strategies based on electric fields to control neural diseases such as epilepsy.