5种药用植物挥发油对仓库害虫生物活性的研究

研究了香薷、鹤虱等５种药用植物挥发油对仓虫的生物活性作用。结果表明,香薷挥发油的作用最为明显,它（剂量０２μＬ／ｇ）及其粗分离１＃～５＃样品（剂量００５μＬ／ｇ）均有效地抑制了试虫卵、幼虫及成虫的生长发育,从而减少了试虫Ｆ１代种群的发生,其中粗分离１＃样品作用尤为突出。香薷挥发油１＃～５＃样品的主要化学成分为４,５,６,７,８,８ａ－六氢－８ａ－甲基－２［１Ｈ］－奥酮（５２６４％）、百里香酚（３０５％）和一未定成分（２１９２％）。     

Porous haydite used as waste water filter medium for lake sludge

Porous haydite used as waste filter medium was prepared by dreging lake sludge to help solve the treatment problem of sludge and realize its reclamation. Several calcination regimes were considered and their effects on the pore structure and the properties such as the strength, the density, the filtering ability and the phosphate absorption ability of the haydite were investigated. For the mixture of 60% lake sludge and 40% fly ash in this experiment, the calcination regime with a pre-calcination period at about 600 °C, a temperature keeping period at 1 200 °C and a moderate cooling rate are recommended to prepare haydite with reasonable pore structure and good performances for its usage as the waste water filter media.     

羊湖电站压力钢管焊接试验成果介绍

羊卓■湖抽水蓄能电站压力钢管现场焊接试验的测试结果表明，在焊接和热影响区未出现任何裂纹；尽管在热影响区内存在窄狭的脆化和软化区，但对焊接接头的承载能力没有影响．这说明施焊单位采用的焊接工艺及热处理是合理的，焊工和焊接设备经受住了高原自然环境的考验．证明了在高海拔，低气压，低温和严重缺氧的条件下，采用现场手工焊接压力钢管的方案是可行的．     

碳纳米管随机网络场效应晶体管电学性能分析

利用电子束蒸发技术在Si衬底形成Au电极作为底栅电极,在底栅电极上生长SiO₂薄膜。超声分散CVD法合成的商用单壁碳纳米管(SWCNTs),使用匀胶机将单壁碳纳米管悬浮液均匀旋涂于SiO₂薄膜上。再利用荫罩式电子束蒸发技术,在单壁碳纳米管随机网络薄膜表面制备漏源电极。该工艺过程避免了碳纳米管过多的化学接触,有效地保护了碳纳米管的性状。在室温条件下对器件电学性能进行测试和分析。使用该方法制备的单壁碳纳米管随机网络薄膜场效应晶体管,具有器件性能稳定、重复性和一致性较好等优点,并可用于构建碳纳米管逻辑电路。该方法对于研究基于碳纳米管的大规模、低成本的集成电路,具有较高的借鉴价值。     

剩余飞行时间估计改进算法研究

针对末制导中剩余飞行时间估计算法误差较大,致使制导精度偏低的问题,提出速度弹道轨迹法和弹目视线平均速度法以精确估计剩余飞行时间。速度弹道轨迹法是通过对速度通过的弹道轨迹进行分割积分计算来求解剩余飞行时间;弹目视线平均速度法是在弹目视线上实时计算平均速度的方法来求解剩余飞行时间。将其应用于多约束条件下的飞行器最优末制导律中,仿真结果表明新算法具有很高的估计精度。     

基于NTSM的自适应最优滑模末制导律设计

针对基于线性滑模面的最优末制导律存在的视线角误差和角速率误差渐近收敛、鲁棒性较弱等不足,提出一种基于非奇异终端滑模(nonsingular terminal sliding mode,NTSM)的最优滑模末制导律。算法基于改进的非线性滑模面以解决普通Terminal滑模因参数选择不当出现的奇异问题,实现误差矢量的有限时间收敛。飞行器在该末制导律导引下,视线角误差及角速度误差快速收敛,从而保证飞行器具有较高的命中精度并满足约束条件要求。仿真结果表明该制导律的适用性及较强鲁棒性。     

温湿度对嗜卷书虱实验种群生长发育的影响

本文报道了不同温湿度组合条件对嗜卷书虱实验种群生长发育的影响,结果表明：温湿度对嗜卷书虱实验种群的生长发育影响极其显著。各虫态发育历期一般随着温湿度的升高而变短,温度的影响更显著;各期的存活率则随着温湿度的升高而升高,湿度的影响更大。把嗜卷书虱的世代历期与世代存活率与温度（X1）和湿度（X2）作回归得方程为：世代历期＝105．3252－3．9006X1＋0．0392X^21－0．0003X^22(R＝0．9822,P＜0．01）;世代存活率＝－330．1287＋8．7139X1＋6．7602X2－0．2290X^21－0．0497X^22＋0．0585X1X2（R＝0．9792,P＜0．01）。嗜卷书虱卵发育的起点温度为9．93℃,有效积温187．15日度;若虫发育的起点温度13．77℃,有效积温184．52日度;完成一个世代所需的有效积温为371．67日度。     

大孔TiO_2-ZnO复合纳米材料的制备及其性能

采用溶胶-凝胶法和胶态晶体模板法,制备了大孔TiO2-ZnO复合纳米材料。其晶相结构和形貌特征采用X射线粉末衍射(XRD)、透视电子显微镜(TEM)进行了表征,并以甲基橙为降解对象,对其光催化活性进行了研究。结果表明,采用无皂乳液聚合法得到的聚苯乙烯(PS)微球粒径均匀,为900nm。以紧密堆积的PS胶态晶体为模板,制得的TiO2-ZnO复合纳米材料的大孔孔径约为900nm,孔壁厚度约为20nm。XRD结果显示,材料中的TiO2为锐钛矿型。光催化降解结果表明,大孔TiO2-ZnO复合纳米材料对甲基橙降解1.5h后降解率可达91.3%,与普通的TiO2-ZnO纳米粉体材料相比提高了11.2%.     

改善误码性能的索引调制正交频分复用混合映射方案

为进一步提升索引调制正交频分复用(OFDM-IM)系统在高信噪比(SNR)条件下的误比特率(BER),该文提出一种混合映射方案。该方案利用高信噪比时索引比特比数据比特错误率更低的特性,混合使用两种不同位数的索引比特分配策略,提高了索引比特的占比。相应地,将子载波激活模式(SAPs)分为超级SAPs和普通SAPs,相比于普通SAPs,超级SAPs对应的索引比特和数据比特分别增加1 bit和减少1 bit。将超级SAP对应的数据比特采用奇偶校验的方式补齐,然后映射为数据符号,提高了系统的分集度,增大了数据符号间的最小欧氏距离。仿真结果表明,相比于以往的映射方案,混合映射方案在误比特率为10^–4时可取得1～3 dB的性能增益,有效改善索引调制OFDM系统的误码性能。     

Effect of electron beam irradiation on polyacrylonitrile precursor fibers and stabilization process

The electron beam was imposed on the polyacrylonitrile precursor fibers before the fibers were stabilized. The effect of electron beam irradiation on the chemical structure, transverse section, and surface morphology and thermal properties of the fibers in the process of stabilization was characterized by the use of Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and differential scanning calorimeter, respectively. A parameter η = I(C?N)/[I(C?N) + I(C?N)] was defined to evaluate the extent of cyclization in the stabilization process. The kinetic parameters, viz. activation energy (E) and pre‐exponential factor (A) of the stabilization reactions, were calculated by Kissinger method. FTIR analysis indicated that the cyclization of nitrile groups was initiated at room temperature by electron beam irradiation. The transformation of C?N groups to C?N ones was accelerated in the process of stabilization. The extent of cyclization of the stabilized fibers was increased. SEM analysis indicated that irradiation could also decrease the internal and surface defects of the stabilized fibers treated at 300°C. The activation energy of cyclization reaction was reduced from 302 to 280 kJ/mol and 260 kJ/mol through 100 and 200 kGy electron beam irradiation, respectively. The reaction temperature range was expanded, and the exothermic rate was slowed down in the process of stabilization, which was the reason why the stabilized fibers have improved cyclization degree and less internal defects. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011