Deploy Efficiency Driven k-Barrier Construction Scheme Based on Target Circle in Directional Sensor Network

Journal of Computer Science and Technology - With the increasing demand for security, building strong barrier coverage in directional sensor networks is important for effectively detecting...     

耐高温的硼改性酚醛树脂涂敷砂

由碱法酚醛树脂与硼酸制成硼改性酚醛树脂（乙醇溶液），再与粒径0．4～0．8mm的石英砂一起制成树脂涂敷砂．经组分筛选得到实用配方如下（以质量计）：石英砂100％．树脂10％，偶联剂ST-30．15％～0．20％。增韧剂ZF-0.1 0．9％～1．0％。由100g石英砂＋10g树脂＋0．9g增韧剂＋0．2g偶联剂组成、在水介质中于70℃固化反应72小时，再在180～360℃不同温度下老化24小时得到的固结砂样，抗压和抗张强度在老化温度为200℃时最高．分别为12．1和7．7MPa，老化温度300℃时分别为9．7和4．2MPa，符合防砂要求；老化温度在240～300℃时空气渗透率为32．6～34．1时。在以蒸汽吞吐方式开发、油井出砂严重的胜利孤岛稠油油田，从2002年开始用该树脂涂敷砂进行防砂施工128井次，施工成功率98．6％，平均注汽温度305℃，注汽质量流量13．5t／h．平均有效期298天。表5参2。     

Different Responses of an Invasive Clonal Plant <Emphasis Type="Italic">Wedelia trilobata</Emphasis> and its Native Congener to Gibberellin: Implications for Biological Invasion

The invasive clonal plant Wedelia trilobata contains higher levels of ent-kaurane diterpenes, which are precursors of gibberellins (GAs), and higher rates of clonal growth than its native congener W. chinensis in invaded habitats. We hypothesized that the higher levels of endogenous GAs facilitate greater ramet growth in W. trilobata compared with W. chinensis. We quantified endogenous levels of GA₁₊₃ in the two species and compared their growth responses to the changes of endogenous and exogenous GA₃ by using short-term and long-term hydroponics experiments. After a period of homogeneous cultivation, levels of endogenous GA₁₊₃ were higher in W. trilobata than in W. chinensis. The reduction of endogenous GAs repressed the emergence of adventitious roots and the growth of W. trilobata in the initial cultivation stage, and inhibited its shoot elongation and biomass. Levels of endogenous GA₁₊₃ were positively correlated with the length of shoots and adventitious roots of W. trilobata. Adventitious roots of W. trilobata also emerged earlier and grew faster when treated with exogenous GA₃. In contrast, exogenous GA₃ treatment inhibited the length of adventitious roots in W. chinensis, and levels of endogenous GA₁₊₃ did not correlate with shoot or adventitious root length. Our study suggests that GAs accelerate the rapid clonal growth of W. trilobata, more than that of its native congener W. chinensis, illustrating the relationship between plant hormones and the clonal growth of invasive plants. These findings are important for understanding the mechanisms associated with the invasiveness of clonal plants and their potential management.     

一种基于临时证书的互联网实名认证方案

互联网实名认证是国家正在进行探索的规范互联网使用的重要举措,文中从互联的访问特点出发,利用已有的互联网安全技术手段,提出了一种基于临时证书的实名认证方案.本方案不仅利用了数字证书实现身份认证的安全性,而且避免了数字证书在管理方面的一些缺陷,同时设计了实名认证的主要协议流程,并进行了安全性分析.     

高效液相色谱法测定食品用尼龙膜中己内酰胺迁移量不确定度的评定

目的评定高效液相色谱法(high performance liquid chromatography,HPLC)测定食品用尼龙膜中己内酰胺迁移量的不确定度。方法依据GB 31604.19-2016《食品安全国家标准食品接触材料及制品己内酰胺的测定和迁移量的测定》,采用高效液相色谱法分析研究食品用尼龙膜水基模拟液己内酰胺迁移量不确定度的大小。并建立数学模型,从测量结果的重复性、标准溶液配制、样品预处理、标准曲线拟合、空白溶液等方面,分析不确定度的来源,然后计算合成不确定度。结果测量结果的重复性、标准溶液配制、标准曲线拟合、样品预处理的相对不确定度分别为:0.00048、0.00916、0.01082、0.00289,合成不确定度为0.01448。样品中己内酰胺迁移量测量值的平均值为10.731 mg/L,其扩展不确定度为0.31 mg/L(k=2),则测量结果和不确定度的描述为(10.73±0.31)mg/L(k=2)。结论校准曲线拟合求浓度对己内酰胺迁移量的影响最大。日常检验中要保持仪器的稳定性、高灵敏度,并对仪器及时进行检定和期间核查。