Spatial and temporal characteristics of VHF radiation source produced by lightning in supercell thunderstorms

The three-dimensional temporal and spatial characteristics of VHF radiation events produced by lightning discharges in three supercell thunderstorms have been analyzed based on the data measured by the lightning mapping array system with high time and space resolution. The results indicate that lightning hole (lighting free region) with about 5-6km in diameter or lighting ring (annular lighting free region) is associated with the strong updraft in thunderstorm.The lasting time of lightning holes is either short or long, being about 20min in a tornado-producing thunderstorm. The lightning holes appear before the occurrence of tornado.The lightning hole is the most obvious during the occurrence of tornado and some self-existent lighting radiation events appear at a height of 15-16km. The lightning channels of inter-cloud (IC) lightning discharge exhibit clockwise rotary structures and do not have clear bilevel structures in the vicinity of the tornado.The lightning holes are corresponding to the strong updraft region.The temporal and spatial distribution of lightning radiation events reveals the structure of strong updraft in supercell thunderstorms.Positive cloud-to-ground (CG) lightning discharges dominate in these thunderstorms and the peak of positive CG lightning flash rate appears, with the maximum of 6 per minute,after or before the occurrence of tornado.     

浅谈信息时代对期刊管理人员的素质要求

信息时代推动了图书馆期刊工作的变革,也对图书馆期刊管理人员提出了更高的要求。论述了信息时代期刊管理人员必须具备的素质。     

酞菁功能化纳米纤维对染料废水的脱色研究

将酞菁表面功能化纤维素纳米纤维材料CoPc‐NF应用于活性艳红X‐3B染料废水的脱色处理。实验发现CoPc‐NF对染料分子有较强的吸附能力,溶液中有H2 O2氧化剂存在时,CoPc能快速有效地使活性艳红X‐3B溶液催化氧化降解脱色。利用单因素实验方法研究了染料溶液的最佳脱色条件。结果表明：CoPc为365μmol／g、溶液pH ＝2、反应温度为50℃、H2 O2为8 mmol／L时,经过90 min催化氧化反应,CoPc‐NF／H2 O2反应体系可使活性艳红X‐3B溶液浓度下降90％以上。     

复杂血管内两相流数值模拟

为了更全面的了解复杂血管内部流动状况,采用液固两相流模型和脉动速度入口条件,对分叉弯曲复杂血管内部两相流动进行模拟分析。通过对其压力、速度、流线、壁面剪切应力、红细胞体积浓度分布等流动参数分析,发现在血管弯曲和分叉区域,血液流动复杂,容易产生低速回流区或二次回流,而且剪切应力较低,红细胞体积浓度较高。     

盐胁迫下盐芥和拟南芥内源激素质量分数变化的研究

采用酶联免疫吸附(ELISA)法测定了盐胁迫下盐芥(Thellungiella halophila)和拟南芥(Arabidopsis thaliana)叶片中生长素(IAA)、赤霉素(GA)、细胞分裂素(ZR)和脱落酸(ABA)等4种内源激素的质量分数,分析了2种植物的4种内源激素在盐胁迫下的响应特征.结果表明:48 h盐胁迫下拟南芥中的ABA质量分数增加2～2.7倍,是主要的胁迫响应激素;盐芥中呈积累增加的是IAA、ZR、GA,皆为促进生长的激素.说明盐胁迫下2种植物的激素应答方式不同.     

新型谷胱甘肽响应三嵌段聚前药两亲分子的构筑与纳米结构调控

针对肿瘤组织的还原性微环境,设计了一种基于谷胱甘肽(GSH)还原性响应的三嵌段聚前药两亲分子,聚喜树碱-嵌段-聚乙二醇-嵌段-聚喜树碱(PCPTM-b-PEG-b-PCPTM),具有很高的载药量(质量分数大于50%).采用大分子自组装的方法,通过调节共溶剂种类,实现了两种不同纳米结构组装体的构筑.利用透射电镜(TEM)和扫描电镜(SEM)进行表征,采用1,4-二氧六环(1,4-dioxane)作为共溶剂组装得到错列堆积片层结构,改变共溶剂为N,N-二甲基甲酰胺(DMF)时,得到了大复合胶束结构.进一步的细胞实验表明,错列堆积片层结构和大复合胶束结构纳米粒子都具有较快的肿瘤细胞内吞速率和较好的抗肿瘤效果.     

基于实物期权的房地产开发价值评估研究

未来不确定的条件下,传统NPV分析方法在价值评估中使用受到限制。通过积极、动态、实时的管理创造项目价值,运用项目管理者的柔性决策空间、实物期权思想及其二项式期权定价模型,确定投资项目中的实物期权价值,可以在一定程度上弥补传统方法的缺陷。基于实物期权分析框架,考虑实物期权价值,寻找项目现值投资决策的临界值;并运用实物期权分析方法,充分挖掘项目中不确定条件下所蕴涵的灵活性价值,对房地产开发项目中的价值进行正确评估。     

Analysis of 3-D Frictional Contact Mechanics Problems by a Boundary Element Method ＊

The development of two boundary element algorithms for solving 3-D, frictional, and linear elastostatic contact problems is reported in this paper. The algorithms employ nonconforming discretizations for solving 3-D boundary element models, which provide much needed flexibility in the boundary element modeling for 3-D contact problems. These algorithms are implemented in a new 3-D boundary element code and verified using several examples. For the numerical examples studied, the results using the new boundary element algorithms match very well with the results using a commercial finite element code, and clearly demonstrate the feasibility of the new boundary element approach for 3-D contact analysis     

半散养麋鹿角的特征及其脱落生境选择

对麋鹿角的形状、定形模式、阶段性生发趋势、脱落时间及其脱落时生境选择进行探讨.角的特征分析表明:麋鹿角主杆分枝复杂,后枝生有小枝(0～4),各种年龄阶段麋鹿角的动态定形模式:独角(2YEAR)→二杈(3YEAR)→三杈(4YEAR)→四杈(≥5YEAR)→五杈,并且角萌发的高峰期为独角→二杈期,然后趋向于1.角的脱落时间分布和生境选择的结果说明:雄性麋鹿年龄越大角的脱落趋向越早(P<0.01),脱落的角分布于麋鹿正常活动范围内,其主要生境选择冬季人工补饲点、树林、草丛、光裸地、水塘等,贡献率分别为:40.39%、30.77%、21.15%、4.81%、2.88%.     

中频宽带信号采集存储回放系统设计

目前中频宽带信号在通讯及雷达领域中的应用十分广泛,为了将无法实时处理的信号后续再处理以及将采集到的信号在其他地点重现,设计了一种中频宽带信号采集存储回放系统.基于FPGA(field-programmable gate array)+ADC(ana-log-to-digital converter)/DAC(digit...