54 research outputs found
LINP: Supporting similarity search in unstructured peer-to-peer networks
No full textLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)4505 LNCS127-13
iSky:Efficient and Progressive Skyline Computing in a Structured P2P Network
No full textAn interesting problem in peer-based data management is efficient support for skyline queries within a multiattribute space. A skyline query retrieves from a set of multidimensional data points a subset of interesting points, compared to which no other points are better. Skyline queries play an important role in multi-criteria decision making and user preference applications. In this paper, we address the skyline computing problem in a structured P2P network. We exploit the iMinMax(θ) transformation to map high-dimensional data points to 1-dimensional values. All transformed data points are then distributed on a structured P2P network called BATON, where all peers are virtually organized as a balanced binary search tree. Subsequently, a progressive algorithm is proposed to compute skyline in the distributed P2P network. Further, we propose an adaptive skyline filtering technique to reduce both processing cost and communication cost during distributed skyline computing. Our performance study, with both synthetic and real datasets, shows that the proposed approach can dramatically reduce transferred data volume and gain quick response time
Efficient Skyline Computation in Structured Peer-to-Peer Systems
No full textUdgivelsesdato: JULAn increasing number of large-scale applications exploit peer-to-peer network architecture to provide highly scalable and flexible services. Among these applications, data management in peer-to-peer systems is one of the interesting domains. In this paper, we investigate the multidimensional skyline computation problem on a structured peer-to-peer network. In order to achieve low communication cost and quick response time, we utilize the iMinMax(\theta ) method to transform high-dimensional data to one-dimensional value and distribute the data in a structured peer-to-peer network called BATON. Thereafter, we propose a progressive algorithm with adaptive filter technique for efficient skyline computation in this environment. We further discuss some optimization techniques for the algorithm, and summarize the key principles of our algorithm into a query routing protocol with detailed analysis. Finally, we conduct an extensive experimental evaluation to demonstrate the efficiency of our approach
Distributed cache indexing for efficient subspace skyline computation in P2P networks
No full textSkyline queries play an important role in applications such as multicriteria decision making and user preference systems. Recently, more attention has been paid to the problem of efficient skyline computation in the P2P systems. Due to the high distribution of the P2P networks, the skyline computation incurs too many intermediate results transferred between peers, which consumes mass of the network bandwidth. Additionally, a large number of peers are involved in the skyline computation, which introduces both heavy communication cost and computational overhead. In this paper, we propose a novel Distributed Caching Mechanism (DCM) to efficiently improve the performance of the skyline calculation in the structured P2P networks, using a Distributed Caching Index (DCI) scheme and an advanced cache utilization strategy. The DO scheme is employed to efficiently locate the cache that can properly answer a future skyline query. Exploring the property of emended skyline, we can optimize the utilization of the cached results for answering future skyline queries. Extensive evaluations on both synthetic and real dataset show that our approach can significantly reduce both bandwidth consumption and communication cost, and greatly shorten the response time
New paleoscolecid worms from the early Cambrian north margin of the Yangtze Platform, South China
No full textAbstractThe Cambrian Yanwangbian assemblage (Series 2, Stage 4) in South Shaanxi, China, is one of the Burgess Shale–type faunas as it represents the only relatively diverse Cambrian biota from the north margin of the Yangzte Platform, South China. The paleoscolecids (Cycloneuralia) illustrated herein are one of the major components of the fauna, although they appear to be much less abundant than skeletonized fossils, according to available collections. A new taxon, Shaanxiscolex xixiangensis new genus new species, is described based on the scleritome pattern: each annulus has two rows of alternating Hadimopanella-type plates positioned close to the borders, and a mosaic pattern of microplates occurs between the plates and within intersegmental furrows. The occurrence of the new taxon confirms a fairly diversified and widespread distribution of paleoscolecidan worms recognized in the early Cambrian of South China. Moreover, the ecology of paleoscolecids is reappraised based on burial position of the S. xixiangensis and gut contens of Cambrian taxa from South China, hinting that paleoscolecids (at least some taxa) were both deposit feeders and carnivores, as well as active bioturbators in the substrates of the Cambrian sea, which sheds new light on the ‘Cambrian Substrate Revolution.’</jats:p
Pyritized preservation of chancelloriids from the Cambrian Stage 3 ofSouth China and implications for biomineralization
No full textThe enigmatic Cambrian animal chancelloriids were discovered in a wide range of taphonomic settings; however, preservation of biomineralized sclerite microstructure was solely known from secondarily phosphatized skeletal remains. Here, we investigate a uniquely pyritized chancelloriid from the lowerCambrian Guojiaba Formation in southern Shaanxi Province, China, using a combination of advanced analytic techniques. Results of the energy dispersive spectroscopy (EDS), X-Ray Fluorescence (XRF), and Raman spectrum show that the sclerites and scleritomes are preserved as pyritized internal moulds witha calcitic outer layer. The outer layer enveloping the internal moulds likely represents the recrystallized counterpart of the original biomineralized sclerite wall. Distinctive fibrous microstructures are discovered in the sclerites, which echo the features seen in the phosphatized fossils of chancelloriids. The typical microstructure, along with the recrystallized calcite, corroborate the interpretation that chancelloriid sclerites were originally constructed by fibrous aragonite. The stability of the microstructure and mineral composition in both carbonate and siliciclastic backgrounds indicate that chancelloriids were adapted to exploit aragonitic fibres to build their skeletons regardless of the change of their living environments.This study was supported by National Key Research and Development Program (grant number 2017YFC0603101), National Natural Science Foundation of China (grant numbers 41621003, 41890840, 41930319, and 42002011), the Strategic Priority Research Program of Chinese Academy of Sciences (grant number XDB26000000), the 111 Project (grant number D17013), and China Postdoctoral Science Foundation (grant number 2019M663793).</p
Morphology and ontogeny of the eodiscoid trilobite Pagetia vinusta from the Cambrian (Miaolingian) of South China
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Selective Conversion of Renewable Furfural with Ethanol to Produce Furan-2-acrolein Mediated by Pt@MOF-5
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