100 research outputs found

    Research on Key Technology of Information Retrieval Based on Unstructured P2P Network

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    近年来,P2P(peer-to-peer)技术成为人们研究与关注的焦点,以Napster、MSN、BT为代表的P2P应用软件日渐流行。其中,信息共享是最常见的一种应用。在P2P共享系统中,每个Peer节点既可以将本地资源贡献出来与其它节点分享,又可以从其它节点获取资源,实现了服务器与客户端的两位一体。然而,所有P2P共享系统都面临一个难题,即如何在缺少集中控制、大规模、分布式的P2P网络中找到并定位信息。遗憾的是,现有的P2P信息检索机制存在着种种不足:基于结构化P2P网络的检索效率很高,然而由于构造过于严格,难以在Internet上普及,而且仅能支持粗粒度的文件共享;非结构化P2P网络实现简...Peer-to-peer (P2P) technology has recently received a lot of attentions, and many P2P platforms have been developed, such as Napster, MSN, BT, etc. One of the most popular P2P applications is the file-sharing system. In a P2P file-sharing system, each peer performs as both a server and a client, which means they can get resources from remote sites, meanwhile, they are also providing local reso...学位:工学硕士院系专业:计算机与信息工程学院计算机科学系_计算机应用技术学号:20032800

    基于重心Delaunay三角剖分的蓝噪声点采样算法

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    为了生成带有高质量蓝噪声性质的采样分布,提出一种基于重心Delaunay三角剖分的点采样算法.该算法将Delaunay三角剖分与1-邻域三角片重心相结合,迭代地将每个采样点移至其1-邻域三角片的重心处并更新采样点之间的拓扑连接关系;重心通过给定的密度函数计算得出.实验结果表明,本文算法在运行效率与鲁棒性方面均有一定优势.国家自然科学基金(61472332);;福建省自然科学基金(2018J01104

    基于非结构化的P2P 信息检索关键技术研究

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    如何在缺少集中控制、大规模、分布式的P2P (peer2to2peer) 网络中找到并定位信息是所有的P2P 共享系统面临的一个难题. 现有的P2P 信息检索机制存在着种种不足:基于结构化P2P 网络的检索效率很高,然而由于构造过于严格,难以在Internet 上普及,而且仅能支持粗粒度的文件共享;非结构化P2P 网络实现简单,是P2P 共享系统的主要实现方式,但是由于搜索的盲目性,其检索效率又普遍低下. 建立了一个新的非结构化P2P 共享原型系统. 该系统利用改进的蚁群算法进行检索路由,使检索总是倾向于有利的方向. 同时,有针对性的推荐服务能够减少盲目搜索,提高文件共享水平. 仿真实验的结果表明,该系统所采用的信息检索与信息推荐相结合的策略能够有效地提 高P2P 信息检索的成功率,降低网络负载.国家自然科学基金资助项目(60373080) 福建省自然科学基金资助项目(A0310009) 厦门大学985 二期信息技术创新平台资助项目(2004 - 2007) 厦门大学院士启动基金

    Spindle Thermal Error Comprehensive Prediction Model Based on Information Granulation and SVM

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    主轴热变形是影响数控机床加工精度的主要因素。为提高主轴热误差的预测精度,提出了基于信息粒化支持向量机(SVM)的主轴热误差综合预测模型。使用信息粒化方法对采样温度数据与主轴热误差数据进行预处理,分别建立基于SVM的主轴热误差的回归预测模型和时间序列模型,通过计算两个模型权重系数,最终建立主轴热误差综合预测模型。以2MZK7150五轴数控可转位刀片工具磨床为研究对象,实验表明,较之于单一模型该模型具有良好的泛化能力和较高建模精度。Spindle thermal deformation has an extraordinary influence on the NC machining precise. Aiming to the im- provement of the spindle thermal deformation predict ability, the spindle thermal error comprehensive predict model is pro- posed on the basis of the information granulation and support vector machine(SVM). Information granulation method is em- ployed to pretreat the sampling temperature and spindle thermal error. The regression prediction model and time series mod- el of spindle thermal error are also carried out based on the SVM. Finally, the spindle thermal error comprehensive predict model is established using the weight coefficients of the two models. The 2MZK7150 five-axis NC indexable insert tool grinding lathe machining experiment shows that the established model has better generalization ability and higher modeling precision compared with the unitary model.陕西省科技统筹创新工程计划(2014KTD201-04-03

    Functionalization of Silkworm Silk Materials in Optics

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    家蚕蚕丝是一种天然的蛋白质纤维,蚕丝及其衍生物(凝胶、蚕丝薄膜和海绵等)具有独特的力学性能、良好的生物相容性和生物降解性,已经被应用在纺织、生物医学等领域。最近,利用蚕丝独特的性质制备光学功能化蚕丝吸引了研究者的兴趣。基于对蚕丝的丝胶和丝素结构组成的总结,介绍了目前蚕丝结构的相关研究进展,综述了近年来对光学功能化蚕丝的研究,具体包括光学功能化蚕丝的重要种类、制备和应用。重点介绍了荧光性功能蚕丝基因工程、喂食法和复合等制备方法,该种材料用于生物支架成像、药物缓释载体和光学器件等领域。总结了利用生物仿生技术制备具有光子晶体结构色的蚕丝材料,这为化妆品,变色服饰和生物光控器件开辟了新方向;此外,蚕丝材料还可以应用于非线性光学领域,如光限幅和激光防护。As a kind of nature protein,silkworm silk and its derivatives( gels,silk fibroin foams and films) possess the unique mechanical properties,biocompatibility and biodegradability,which have been applied to textile and biomedical industry.Recently,there is a growing interest in introducing optical functionalities into silk.Based on the structure of sericin and fibroin,functionalization of silk was summarized in optics,specifically including the important species,preparation and application of fluorescent silk.This paper highlighted that the fluorescent silk can be produced by genetic engineering,feeding,and compositing etc.,which can be applied in scaffold imaging,drug delivery,and optical devices.In addition,this paper reviewed the fabrication of silk fabrics with photonic crystals structure colors using biomimetic techniques,which opens up a new direction of cometic,color dress,various devices and biological optical devices.At last,silk materials can also be applied in nonlinear optics,such as optical limiting and laser protection.厦门大学中组部千人计划项目配套经

    同步脱氮除磷技术研究进展

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    为避免造成水体富营养化,污水排放前必须进行脱氮除磷处理。与传统技术相比,新型同步脱氮除磷技术具有能耗低、占地小等特点,是污水处理领域中新的工程应用方向。介绍了生物法、物理化学法、生物电化学法和生物诱导矿化法4类同步脱氮除磷技术的原理、特点及影响因素。其中,生物诱导矿化法作为新型的生物-矿物结晶耦合处理技术,在降低运行成本和磷资源回收方面具有较大的优势,成为污水脱氮除磷领域的研究热点。国家自然科学青年基金项目(51808473)国家科技攻关计划项目(2016YFC0502901)国家自然科学基金项目(41771500)中国博士后科学基金项目(2017M610397

    Adaptive Knot Placement in Non-uniform B-spline Surface Fitting

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    针对非均匀b样条的节点设置问题,提出一种利用非均匀b样条曲面拟合离散数据的迭代算法,通过优化节点分布来改进拟合曲面的质量.该算法以带参数化的三角网格曲面为输入,在首次迭代中根据输入曲面的几何特征将其对应的参数域划分成若干个子区域,并使得每个子区域上累积的几何特征信息量近似相等,子区域的重心坐标将取为首次迭代的节点;在随后的迭代中,保证前次迭代生成的重心位置固定不变,并根据前次迭代得到的曲面拟合误差再次将区域划分成累积误差接近相等的子区域,新增加的子区域重心的坐标选为拟加入的节点.文中算法自适应地在曲面形状复杂或拟合误差大的区域引入更多的控制顶点,使得拟合曲面的质量得以逐步改进.实验结果表明,该算法快速有效,在拟合具有明显几何特征的输入数据时具有优势.Knot placement of non-uniform B-spline is studied, and an iterative surface fitting scheme is proposed by exploring the degrees of freedom of knots to improve the fitting surface's quality.Our algorithm takes as input triangular meshes with parameterization.In the first iteration, the parametric domain is partitioned into several sub-regions with equally accumulated surface geometric information, and the coordinates of the centroids are chosen as the candidates of knots; in the following iteration steps, we partition the regions according to the fitting errors analogously while the centroids generated by previous steps remain unchanged.The fitting surface's quality is progressively improved as more control points are adaptively introduced into the region of the surface with more features or larger fitting error.Several experiments demonstrate the efficacy of our method in fitting surface with distinct geometric features.国家自然科学基金(61100105;61100107;61170324;61272300); 福建省自然科学基金(2011J05007;2012J01291

    纳米金簇复合丝素薄膜的性能及其在生物成像中的应用

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    具有荧光性能的丝素薄膜可用于生物体内外实时的、无损伤的生物成像,为直观监测体内生物材料及其化学环境的变化提供了新思路。采用浇铸法制备纳米金簇复合丝素薄膜,研究了纳米金簇、甘油和制备过程中pH值对纳米金簇复合丝素薄膜结构和性能的影响。结果表明:纳米金簇和甘油的加入都会提高纳米金簇复合丝素薄膜β-折叠和结晶度,从而提高其断裂强度;在碱性条件下制备的纳米金簇复合丝素薄膜在680nm处可发射较强荧光;细胞能在制备的薄膜上正常黏附和生长,实现薄膜和细胞同时荧光成像。国家自然科学基金资助项目(51773171,U1405226)福建省科技厅自然科学基金资助项目(2017J06019)高等学校学科创新引智计划资助项目(B16029)厦门大学校长基金资助项目(20720160088,20720150218

    Controlling elementary reaction of bulk ring-opening copo lymerization of octamethylcyclotetrasiloxane with N-β-aminoethyl-γ-aminopropylmethyldimethyoxysilane

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    MonteCarlo方法首次用来揭示八甲基环四硅氧烷(D4)与N-β-氨乙基-γ-氨丙基甲基二甲氧基硅烷(APAEDMS)的本体开环共聚反应机理的关键调控基元反应.基于已提出的该体系本体共聚反应机理,并兼顾模拟精度与计算经济性,MonteCarlo模拟模型采用自由体积理论简化扩散效应并与本征反应动力学方程耦合.其中,本征动力学速率常数通过模拟主要共聚基元反应得到.基于优化的动力学速率常数通过模拟从分子水平上揭示:D4/APAEDMS本体共聚机理为一伴有逐步特征的阴离子连锁聚合.其中,链引发及其逆反应对D4/APAEDMS的本体共聚反应没有直接调控作用,而链缩合及其逆反应是本体系反应机理不同于纯活性阴离子聚合或逐步聚合反应机理的关键原因.The bulk ring-opening copolymerization mechanism of oc ta methylcyclotetrasiloxane (D_4) with N-β-aminoethyl-γ-aminopropy lmethyldimethyoxysilane (APAEDMS) and its key controlling elementary reactions w ere firstly investigated and demonstrated by means of the Monte Carlo method in this paper.With consideration of the cost of computation as well as the precisio n of simulated results, a new computational model was developed to simulate the reaction system based on the free volume theory and the chemical reaction kineti c theory.The intrinsic reaction rate constants were obtained by simulating the m ain elementary reactions of copolymerization. This paper indicates from microsco pic level: (1) The bulk copolymerization mechanism of D_4 with APAEDMS is an an ion chain-reaction mechanism with the characteristics of the step polymerizatio n.(2) The chain-condensation reaction and its reversible reaction are the key c ontrolling elementary reactions of the copolymerization mechanism for the studie d system,while the chain initiation elementary reactions are not the key control ling elementary reactions of the copolymerization mechanism for the studied syst em

    改革开放:中国电影的艺术成就与文化表达

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    钟大丰在市场化进程中探索中国电影学院的追求回顾我们改革开放四十年,从中国的范围来讲,是一个不断走向商品市场开放的过程。电影的发展和市场开放的进程有着特别紧密的关系,当我们跟改革开放的总体进程结合得比较紧的时候,我们会看到电影表现出活力;当我们离开改革开放进程相对比较远的时候,它的活力就会减少,问题就会出现,改革开放这四十年并不一直是一帆风顺的。很多人对80年代的活跃局面很怀念,那个时
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