输水管道设计中的糙率选取问题研究

分析了目前输水管道设计中糙率选取存在的问题，提出了不宜选用单一糙率进行管道水力学计算，而应综合考虑输水水质、水温、管材及制作工艺、管径大小等因素，选取能包络各种运行工况的一定范围的糙率上下限值，作为水力学计算参数，以保证管道输水工程既能在长期运行时达到设计流量，又能安全运行。     

2.5Gbit/s 0.35μm CMOS激光驱动器

设计了一种具有自动功率控制功能的激光驱动器电路.为了获得良好的性能,该驱动器采用级联差分放大器和源极跟随器分别进行信号放大和级间阻抗匹配.该电路的实现采用了0.35 μm标准CMOS工艺.对该电路进行了测试,测试结果表明,在2.5和5 Gbit/s速率下,电路输出信号眼图清晰.在5 V电源电压、2.5 Gbit/s数据速率下,该驱动器可提供0～68 mA范围内的调制电流,满足长距离光纤通信系统的要求.电路典型功耗480 mW,芯片面积为0.57 mm2.     

Transmembrane structure and function of dctPQM encoding C4－dicarboxylate transport proteins from nitrogen－fixing P. stutzeri A1501

C4-dicarboxylate transport proteins of diazotroph Pseudomonas stutzeri were encoded by dctPQM genes. Nucleotide sequence analysis indicated that dctP, dctQ,and dctM grouped together. Its nucleotide and amino acid sequence shared high homology with that of dctP gene encoding periplasmic C4-dicarboxylate-binding protein and dctQM genes encoding C4-dicarboxylate transport proteins from the free-living nitrogen-fixing Aotobacter vinelandii.Structural analysis showed that DctP of P. stutzeri did not include membrane-spanning regions, and DctQ and DctM contained 5 and 12 transmembrane segments, respectively.The fragment containing the complete dctPQM genes was cloned into the Tn5 transposon region of suicide mobilization plasmid pSZ2L The resultant plasmid was named pSZY6.By triparental mating, Tn5 transposon carrying the dctPQM genes inserted into the genome of the wild type strain A1501,randomly. The recombinant strain A-142 which harboured an extra copy of dctPQM genes was constructed and identified by PCR amplification of npt II gene. When A-142 was grown in minimal medium with different concentrations (20,10 and 5mmol/L) of C4-dicarboxylates succinate, malate, or fumarate as the sole carbon source, the rate of nitrogen fixation assayed by acetylene reduction was significantly higher than that of the wild-type strain A150L This result was established that an extra copy of dctPQM genes could increase the activity of nitrogen fixation of P. stutzeri strain A1501.     

基于智慧集料运动特征的级配碎石剪切破坏机理

为深入了解级配碎石混合料剪切破坏机理,研发了智慧集料传感系统,结合级配碎石三轴剪切试验,进行智慧集料运动特征指标与级配碎石剪切行为的关联分析。基于剪切破坏位置,选择了智慧集料埋设位置;以x、y、z三轴方向加速度和角度指标表征智慧集料运动特征。研究结果发现：智慧集料加速度和角度响应规律与级配碎石剪切破坏三阶段变化规律吻合：级配碎石剪切破坏过程中,智慧集料加速度响应经历了由运动缓慢,运动加快到运动突变稳定的变化;且y、z轴方向加速度变化更快。智慧集料角度响应证明了集料颗粒接触各向异性存在,x、y、z三轴方向角度响应差异性大;颗粒转角运动最终主要体现在x、y轴方向上。     

批判导读方式:使文学概论课堂活跃起来

文学概论课程的难教难学,是目前教学中普遍存在的状况。在教学实践中,为有效激发学生兴趣,培养学生的理论品性与实践能力,教师可通过"批判导读"方式,即通过对教材的分析研究和批判性引导,使学生积极参与并逐步形成一定的理论思维和创新能力,从而为有效解决难教难学状况、顺利完成教学目标提供一种方法和途径。     

超声／H2O2／CuO联合作用降解硝基苯

研究了在超声波/H2O2/金属氧化物体系中,金属氧化物(CuO,ZnO,Al2O3)对硝基苯降解的影响。结果表明:采用超声波/H2O2/CuO体系效果较好。对超声/H2O2/CuO联合作用的效果进行了研究,讨论了反应液的pH值、硝基苯的初始浓度等因素对硝基苯降解的影响。实验结果表明:pH值的变化对其降解效果没有明显影响;硝基苯的降解效果与其初始浓度有关,其降解过程符合一级反应动力学模型。     

基于自抗扰控制器的感应电机变频调速系统

设计了由4个一阶自抗扰控制器构成的多环调速系统.该系统将电机模型中的交叉耦合项、易变参数以及负载统一归为未知"扰动",用自抗扰控制器的扩张状态观测器进行观测,并采用非线性状态误差反馈控制器补偿,实现控制系统的精确解耦和简单线性化.该控制方案不需要精确的电机参数,使得自抗扰控制器的设计能够独立于感应电机的精确数学模型.半物理仿真软件SaberDesigner中的器件级仿真实验表明,相对于经典PID控制器,自抗扰控制器对负载扰动和电机参数变化具有更好的鲁棒性和动态性能.     

VRML虚拟场景中复杂动画的实现

利用单纯的VRML语言只能实现静态的三维场景或简单的动画,而不能实现复杂的动画。VRML提供了一个Script脚本节点,通过该节点中的url域并利用Java、JavaScript等语言编写程序,可以在VRML场景中实现比较复杂的动画;Java类包中提供的EAI是增强VRML场景与外部环境通信和融合能力的高层次类包,通过EAI并利用Java编程,可实现对VRML场景的访问并实现可控制的复杂动画。文章依据两个事例,论述了在VRML场景中实现复杂动画的方法及过程。实例表明,通过Script节点和EAI可在VRML虚拟场景中实现可控制的、交互性好的复杂动画。     

Different responses of arbuscular mycorrhizal fungal community to day-time and night-time warming in a semiarid steppe

Arbuscular mycorrhizal （AM） fungi form mutualistic symbioses with most plant species and play important roles in ecosystems. Knowledge of the response of AM fungi to temperature change will improve our under- standing of the function of AM fungal community under global climate change scenarios in ecosystems. The effects of constant warming on AM fungal communities have been investigated previously, but responses to asymmetrical warming over 24-h periods have never been documented in natural ecosystems. In this study, we examined AM fungal communities in a full factorial design including day-time and night-time warming in a semiarid steppe in northern China. Day-time and 24-h warming, but not night-time warming, significantly increased AM fungal spore density. In contrast, none of the three warming regimes had a sig- nificant effect on AM fungal extra radical hyphal density. A total of 161 operational taxonomic units （OTUs） of AM fungi were recovered by 454 pyrosequencing of 18S rDNA. Day-time, night-time, and 24-h warming all significantly increased AM fungal OTU richness. Some AM fungal OTUs showed a significant bias toward day-time, night-time or 24-h warming. The AM fungal community composition was significantly affected by night-time warming, but not by day-time and 24-h warming. Our finding highlighted dif- ferent responses of AM fungal spore density and community composition to asymmetrical warming. This study might improve our understanding of ecosystem functioning of AM fungal community under global climate change scenarios in a semiarid steppe ecosystem.     

浅谈网络管理系统在国内银行业的应用

利用网络管理系统理念,以国内银行网络管理系统的现状分析为基础,从基于Web的网络管理技术、网络管理系统功能、综合化管理与个性化管理之间矛盾、银行对网络管理工作的理解缺失等方面,探析国内银行业在网络管理方面存在的问题和应对策略。