一种优化LDPC码环分布的改进算法

在下一代移动通信系统中,为了满足移动用户对高速、宽带数据传输业务不断增长和更高质量的要求,需要对现有物理层的关键技术作进一步的改进、完善和实用化,例如在信道编码方面,就采用了革命性的LDPC码。而PEG算法则是目前构造中短码长LDPC码最有效的算法之一。通过借鉴ACE算法,在对已有的结构优化设计算法深入理解的基础上,对PEG算法进行了改进,得到了一种可以进一步优化LDPC码环分布和最小距离的改进算法。仿真结果表明：由新算法构造出来的LDPC码的环分布和码重分布都明显优于PEG算法;其性能曲线在低信噪比时与原算法相差不大,而随着信噪比的增加可以有效地降低错误平层。     

Enhanced electrochemical performance of carbon nanospheres-LiFePO4 composite by PEG based sol-gel synthesis

The carbon nanospheres-LiFePO₄ (CNSs-LiFePO₄) composite has been synthesized by PEG (polyethylene glycol, mean molecular weight of 30,000) based sol-gel route. Highly conductive CNSs (30-40 nm) were adopted to improve the electronic conductivity of LiFePO₄. PEG was used to promote the dispersion of CNSs with the surface functionalization of CNSs, which could facilitate the coating of CNSs on the surface of the LiFePO₄ particles. The sample was characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and Raman scattering. Electrochemical performance of the CNSs-LiFePO₄ composite was characterized by the charge-discharge test and electrochemical impedance spectra measurement. The results indicated that LiFePO₄ particles were well coated with the conductive CNSs to overcome the intrinsic low electronic conductivity problem of LiFePO₄. The CNSs-LiFePO₄ composite delivered an enhanced rate capability (146, 128 and 113 mAh g⁻¹ at 0.1 C, 1 C and 5 C rate). The PEG based sol-gel route enables LiFePO₄ networked with CNSs, which offered a higher electrochemical performance.     

Structural and electrochemical studies of PPy/PEG-LiFePO4 cathode material for Li-ion batteries

A simple chemical oxidative polymerization of pyrrole (Py) directly onto the surface of LiFePO₄ particles was applied to the synthesis of polypyrrole-LiFePO₄ (PPy-LiFePO₄) powder. The LiFePO₄ sample without carbon coating was synthesized by a solvothermal method. The polyethylene glycol (PEG) was used as additive during Py polymerization for increasing the PPy-LiFePO₄ conductivity. Properties of resulting LiFePO₄, PPy-LiFePO₄ and PPy/PEG-LiFePO₄ samples were characterized by XRD, SEM, TGA and galvanostatic charge-discharge measurements. These methods confirmed the presence of polypyrrole on LiFePO₄ particles and its homogeneous distribution in the resulting powder material. The PPy/PEG-LiFePO₄ composites show higher discharge capacity than pure LiFePO₄, as PPy/PEG network improves the electron conductivity. It presents specific discharge capacity of 153 mAh/g at C/5 rate.     

添加PEG对钙基烟气脱硫剂结构和性能的影响

针对钙基烟气脱硫剂分散性差、易团聚和比表面积小的缺点,在消化过程中加入不同量的聚乙二醇(PEG600,PEG1500,PEG2000),对消化产物进行改性.结果表明,在搅拌时间30min,水/灰=1.4:1(摩尔比)条件下,PEG600添加量为3%时,消化产物颗粒均匀,平均粒径为9.4μm,比表面积达到21.6m2/g.XRD,SEM和FT-IR测试表明,添加PEG后,石灰消化完全,转化率较高,分散性得到改善,说明PEG对氢氧化钙有一定的包覆作用.     

增韧酚醛泡沫塑料的制备及填料对其性能的影响

以甲阶段酚醛树脂（PF）为基体,聚乙二醇（PEG）和玻璃纤维（GF）为增韧剂,通过抗冲击测试、SEM分析及红外光谱分析（IR spectra）,研究了PEG和GF对改性酚醛泡沫塑料性能的影响。通过综合性能比较得出GF与PEG复合增韧效果最好。结果表明：采用100份酚醛树脂、12份聚乙二醇、0.5份玻璃纤维,温度为80℃,反应时间为30 min,可制备出增韧酚醛泡沫塑料,冲击强度为5.54 kJ/m^2,泡孔细小均匀,粉化率降低7.43%。     

酶法辅助聚二乙醇-200提取杜仲叶中绿原酸的工艺

采用Box-Behnken中心组合实验和响应面分析法,在单因素试验基础上,以酶用量、料液比、pH和酶解时间为影响因素,绿原酸提取率为响应值,对酶法辅助聚乙二醇(PEG)-200提取杜仲叶绿原酸的工艺进行优化。结果表明,其最佳工艺为:酶用量0.8%、料液比1︰20(g/mL),pH 4.4,酶解时间1.6 h。在此工艺条件下杜仲叶绿原酸提取率可达3.15%。该工艺条件温和、易于控制、提取效率高,可为杜仲叶中绿原酸的进一步开发研究提供工艺参考。     

600MW超临界一号机组整套试运分析

对贵州首台超临界机组分部试整套试运完成情况进行了的总结和分析。     

CAWS600系列自动气象站故障分析及排除方法

根据CWAS600系列自动气象站的系统结构和工作原理,将其故障分为：通信、电源供电系统、传感器、采集器四类故障。文章列举了几个典型故障的分析和处理方法。重点介绍了＂测量法＂,通过测量关键点的电信号,将故障进行分级判断和定位。熟悉这些典型故障的处理方法,可以大大提高自动气象站故障排除的时效性。     

聚乙二醇—DPCO萃取光度法测定油中铬（Ⅵ）

本文研究了铬（Ⅵ）—二苯偶氮羰酰肼（DPCO）—聚乙二醇（PEG）体系的萃取和显色反应条件。在pH值为2.0的盐酸-氯化钾缓冲体系中,采用萃取分光光度法,直接测定了油样中的铬（Ⅵ）。铬（Ⅵ）的最大吸收峰位于550nm处,铬（Ⅵ）含量在0～25μg/10mL范围内服从比尔定律。摩尔吸光系数ε550=1.9×105L·mol-1·cm-1,相关系数r=0.9996。实验结果表明：人工合成样的平均回收率为97.73%,相对标准偏差（RSD）为3.19%。采用该方法测定了阿曼原油和减二线油中的铬（Ⅵ）,其含量分别为1.164μg·g-1和3.432μg·g-1,它们的相对标准偏差（RSD）分别为1.77%和2.16%。阿曼原油和减二线油中铬（Ⅵ）的加标平均回收率分别为97.80%和99.82%。研究结果表明,该方法具有操作简便、灵敏度较高、对环境无污染等特点,是集萃取和显色为一体的测定油样中铬（Ⅵ）的好方法。     

Fabrication,characterization and evaluation of the effect of PLGA and PLGA–PEG biomaterials on the proliferation and neurogenesis potential of human neural SH-SY5Y cells

In recent years with regard to the development of nanotechnology and neural stem cell discovery, the combinatorial therapeutic strategies of neural progenitor cells and appropriate biomaterials have raised the hope for brain regeneration following neurological disorders. This study aimed to explore the proliferation and neurogenic effect of PLGA and PLGA–PEG nanofibers on human SH-SY5Y cells in in vitro condition. Nanofibers of PLGA and PLGA–PEG biomaterials were synthesized and fabricated using electrospinning method. Physicochemical features were examined using HNMR, FT-IR, and water contact angle assays. Ultrastructural morphology, the orientation of nanofibers, cell distribution and attachment were visualized by SEM imaging. Cell survival and proliferation rate were measured. Differentiation capacity was monitored by immunofluorescence staining of Map-2. HNMR, FT-IR assays confirmed the integration of PEG to PLGA backbone. Water contact angel assay showed increasing surface hydrophilicity in PLGA–PEG biomaterial compared to the PLGA substrate. SEM analysis revealed the reduction of PLGA–PEG nanofibers' diameter compared to the PLGA group. Cell attachment was observed in both groups while PLGA–PEG had a superior effect in the promotion of survival rate compared to other groups (p < .05). Compared to the PLGA group, PLGA–PEG increased the number of Ki67⁺ cells (p < .01). PLGA–PEG biomaterial induced neural maturation by increasing protein Map-2 compared to the PLGA scaffold in a three-dimensional culture system. According to our data, structural modification of PLGA with PEG could enhance orientated differentiation and the dynamic growth of neural cells.