27 research outputs found

    支持权重优先等级的自适应接入机制

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    研究IEEE 802.11e协议中吞吐量权重比例公平性问题,提出基于业务负载增量估计算法的自适应分布式信道接入机制。给出竞争窗口(CW)关于业务负载线性调整规则,建立接入参数与动态网络条件的关联;提出业务负载的增量估计算法;通过引入优先等级因子参数和多阈值设置,支持吞吐量权重比例的优先等级(WPL)并获得更好的总吞吐量性能。CW决定了节点接入信道的概率,保证了吞吐量权重公平性性能。仿真结果表明了自适应接入机制的有效性和可扩展性。海南自然科学基金项目(617110、617121、618MS083);;\n国家自然科学基金项目(61362016、61502127、61562022、61562023);;\n国家国际科技合作专项基金项目(2014DFA13140);;\n海南省重大科技计划课题基金项目(ZDKJ2017012

    Relationship between genetic lineages and pathotypes of Magnaporthe grisea isolates from Fujian

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    采用rEP-PCr技术对福建省189个稻瘟病菌菌株进行dnA指纹图谱分析.结果表明:在58%相似水平上可以将供试菌株分为15个遗传谱系,表明该菌具有丰富的多态性.其中谱系fJl04出现频率为35.98%,为优势谱系.利用全国统一生理小种鉴别体系和lTH-nIlS鉴别体系从供试的189个稻瘟病菌株中分别鉴别出15和21个致病型(生理小种),优势型分别为zb13和J76.2,出现频率分别为58.72%和28.57%.采用这2套鉴别体系鉴别的致病型与dnA指纹图谱之间无明显的对应关系.The DNA fingerprints of 189 isolates of Magnaporthe grisea from Fujian were constructed using rep-PCR technique.All isolates could be divided into 15 genetic lineages at 58% similarity level.Among the 15 genetic lineages,FJL04 that consisted of 68 isolates was recognized as dominant lineages with occurrence frequency of 35.98%.The 189 isolates could be respectively classified into 15 and 21 pathotypes by Chinese race differentials and LTH-NILs,and their dominance types were ZB13 and J76.2 with occurrence frequency of 58.72% and 28.57%,respectively.There was no obviously corresponding relationship between pathotypes and genetic lineages.福建省科技厅资助项目(2005N030、2006N0034);福建省农科院青年科技人才创新基金资助项目(200708

    新型稠环电子受体的界面修饰对钙钛矿太阳能电池性能的影响

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    钙钛矿太阳能电池(perovskite solar cells, PSCs)因具有能量转换效率(power conversion efficiency, PCE)高、成本低、易于大面积制造等优点而被科学家们广泛关注.氧化物电子传输层的合理界面设计及修饰对提高器件的PCE和工作长期稳定性有着十分重要的意义.因此,本文采用一种含有烷基噻吩基侧链的稠环电子受体材料3,9-二(2-亚甲基-(3-(1,1-二氰甲烯基)-茚酮))-5,5,11,11-四(5-己基噻吩)-二噻吩并[2,3-d:2′,3′-d′]-s-引达省[1,2-b:5,6-b′]二噻吩(3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(5-hexylthienyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene, ITIC-Th)修饰TiO2电子传输层,制备高效稳定的平面结PSCs.研究结果显示,ITIC-Th的界面修饰改善了TiO2薄膜的形貌、接触角等性质,促进了钙钛矿晶粒的高质量生长,大幅度减少了器件表界面的电荷复合,明显提升了光生载流子的抽取率和输运效率,使经ITIC-Th界面修饰的PSC的PCE从未经界面修饰的15.43%显著提高到18.91%.与此同时,器件稳定性的研究结果显示,在室温和湿度为30%的条件下,经ITICTh界面修饰的PSC的PCE在放置约1000 h后依然保持原来的90%,明显高于未经界面修饰的PSC.研究结果对PSC光伏性能的提升具有重要的实际应用价值和学术意义.国家自然科学基金(61605164);;\n陕西省重点科技创新团队计划(2016KCT-28);;\n陕西省重点研发计划(2017ZDXM-GY-046);;\n福建省科技厅高校产学合作项目(2016H6023)资

    Zooplanktonic diversity in the western Pacific

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    西太平洋区是全球海洋生物种源中心,许多类群的最高物种多样性都出现于该区域,因此,在该区开展种类多样性的研究不仅重要和必要,而且具有在跨国尺度上进行综合管理和相互合作的迫切性。本文在西太平洋的浮游动物样品鉴定分类、编目、文献资料整理和分析的基础上,记录和编入西太平洋10个浮游动物类群2,658种(含亚种),隶属于206科675属,其中水螅水母类99科251属697种,栉水母类12科22属59种,浮游软体动物14科35属86种,介形类8科89属416种,桡足类51科156属908种,糠虾类4科58属202种,磷虾类2科8属56种,十足类8科22属105种,毛颚类5科8属48种,被囊类5科26属81种。The western Pacific region has been operating as a centre for the origin of marine biodiversity: the richest diversity of many marine taxa was found in these waters.Therefore,biodiversity research and con-servation efforts in this area are necessary in order to promote the integrative and international management of this resource.The present work is a compilation of numbers of all the families,genera and species of ma-jor taxa of zooplankton known in the western Pacific Ocean(106°–150°E,0°–44°N).In all,2,658 zooplank-tonic species(including subspecies) belonging to 206 families and 675 genera have been recorded from taxonomic identifications and literature,99 families,251 genera and 697 species belong to the Medusozoa,12 families,22 genera and 59 species to the Ctenophora,14 families,35 genera and 86 species to the pelagic Molluscs(Pteropoda and Heteropoda),8 families,89 genera and 416 species to the Ostracoda,51 families,156 genera and 908 species to the Copepoda,4 families,58 genera and 202 species to the Mysidcea,2 fami-lies,8 genera and 56 species to the Euphausiacea,8 families,22 genera and 105 species to the Decapoda,5 families,8 genera and 48 species to the Chaetognatha,5 families,26 genera and 81 species to the Tunicata.908专项“中国海洋生物种类名录和图谱”(908-ZC-II-02)和908专项海洋生物样品库;科技部基础工作专项“我国和邻近西北太平洋海洋生物物种编目和分布图集编制”(2006FY220700

    Lift of a bio-inspired flapping wing with a dynamic trailing-edge flap in forward flight

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    Unlike the tail of a bird, regarded as a separately controlled aerodynamic surface, the membrane tail of a bat is operated as a dynamic trailing-edge flap. We investigate the effects of a dynamic trailing-edge flap on unsteady lift by numerically solving the Navier-Stokes equations around a bio-inspired flapping wing. The peak of the lift coefficient in the downstroke is considerably affected by the phase difference between the dynamic trailing-edge flap and the elevation. A quasi-steady formula is proposed to model the effects of phase difference on lift. The model is consistent with numerical results and experimental observations

    Publicly Verifiable Outsourced Database with Full Delegations

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    为解决可验证外包数据库方案存在的预处理阶段开销较大及不支持公共可验证的问题,提出了一个全委托的公共可验证的外包数据库模型.给出了模型的架构及交互流程,对模型进行了形式化定义,并给出了模型的正确性定义和安全性定义.利用双线性映射及可验证外包模幂运算协议,构建了一个全委托的公共可验证外包数据库方案,且给出了各个算法的详细描述,证明了方案的正确性和安全性.其安全性可规约为BDHE(bilineardiffie-hellman exponent)难题.与现有方案及不进行全委托计算的方案相比,全委托的公共可验证的外包数据库方案基于可验证外包模幂运算,将大量模幂运算外包给云处理,减小了数据拥有者的开销.理论与实验分析表明:该方案数据拥有者在预处理阶段所需的代价更低,效率更高,适于实际应用.此外,验证过程无需私钥参与,实现了公共可验证.</p

    Fuzzing test case generation method for industrial control protocol based on improved mutation-tree

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    针对现有应用层工控协议在模糊测试过程中用例冗余度高、测试效率低和随机性强等问题,提出一种基于改进变异树的测试用例生成方法。该方法将协议样本数据序列进行树结构化,同时提取协议规约中字段优先级信息,并利用其有效地控制树中各节点属性值的变异程度,从而达到降低测试成本、提高测试效率以及增大发掘漏洞几率的目的。实验结果表明,提出的测试用例生成方法对提高协议模糊测试性能具有显著的优化效果和漏洞检测能力。</p

    Study on the influence of initial pH on nitrification in aquaculture seawater

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    本工作进行了一系列实验,研究pH对养殖海水硝化作用的影响.结果表明,水体硝化作用受到pH的影响,硝化作用适宜的水体pH范围为弱碱性.在水体初始pH值为8.10时,硝化的速率为2.416μmol/(d.dm3),水体的硝化率达到最大.硝化作用基本符合一级反应的动力学模式.A series of experiments were conducted on the impact of initial pH on nitrification in aquaculture seawater.The result indicates that nitrification was influenced by pH and optimized in alkalescence water.The nitrification efficiency maximized when the initial pH was 8.10 with rate of 2.416μmol/(d·dm3).Nitrification in aquaculture water column accords with the first order kinetics.福建省专项基金资助项目(2005021477);; 福建省自然科学基金资助项目(D0610020

    Lightweight authentication method for supporting anonymous access of heterogeneous terminal in edge computing scene

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    本发明提出了边缘计算场景下支持异构终端匿名接入的轻量级认证方法。该发明利用云平台为每个终端设备创建伪身份来隐藏其真实的身份信息,同时还可以对恶意终端设备进行追溯,在终端设备接入边缘计算节点认证过程中,边缘计算节点可以在不与云平台通信的情况下实现对所有接入的设备身份的合法性进行验证,且不会学习到终端真实身份信息,保障了终端设备的身份隐私性,提高了接入认证的效率,且可以抵御重放攻击等常见威胁,增强了整个边缘计算系统的安全性与可靠性,解决边缘计算场景下资源受限的终端设备接入认证问题
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