1,471 research outputs found

    Classification under Streaming Emerging New Classes: A Solution using Completely Random Trees

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    This paper investigates an important problem in stream mining, i.e., classification under streaming emerging new classes or SENC. The common approach is to treat it as a classification problem and solve it using either a supervised learner or a semi-supervised learner. We propose an alternative approach by using unsupervised learning as the basis to solve this problem. The SENC problem can be decomposed into three sub problems: detecting emerging new classes, classifying for known classes, and updating models to enable classification of instances of the new class and detection of more emerging new classes. The proposed method employs completely random trees which have been shown to work well in unsupervised learning and supervised learning independently in the literature. This is the first time, as far as we know, that completely random trees are used as a single common core to solve all three sub problems: unsupervised learning, supervised learning and model update in data streams. We show that the proposed unsupervised-learning-focused method often achieves significantly better outcomes than existing classification-focused methods

    The verification of the Taylor-expansion moment method in solving aerosol breakage

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    The combination of the method of moment, characterizing the particle population balance, and the computational fluid dynamics has been an emerging research issue in the studies on the aerosol science and on the multiphase flow science. The difficulty of solving the moment equation arises mainly from the closure of some fractal moment variables which appears in the transform from the non-linear integral-differential population balance equation to the moment equations. Within the Taylor-expansion moment method, the breakage-dominated Taylor-expansion moment equation is first derived here when the symmetric fragmentation mechanism is involved. Due to the high efficiency and the high precision, this proposed moment model is expected to become an important tool for solving population balance equations

    Temporal similarity metrics for latent network reconstruction: The role of time-lag decay

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    When investigating the spreading of a piece of information or the diffusion of an innovation, we often lack information on the underlying propagation network. Reconstructing the hidden propagation paths based on the observed diffusion process is a challenging problem which has recently attracted attention from diverse research fields. To address this reconstruction problem, based on static similarity metrics commonly used in the link prediction literature, we introduce new node-node temporal similarity metrics. The new metrics take as input the time-series of multiple independent spreading processes, based on the hypothesis that two nodes are more likely to be connected if they were often infected at similar points in time. This hypothesis is implemented by introducing a time-lag function which penalizes distant infection times. We find that the choice of this time-lag strongly affects the metrics' reconstruction accuracy, depending on the network's clustering coefficient and we provide an extensive comparative analysis of static and temporal similarity metrics for network reconstruction. Our findings shed new light on the notion of similarity between pairs of nodes in complex networks

    Design of super-efficient mixer based on induced charge electroosmotic

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    The super-efficient sample mixing induced by the induced-charge electrokinetic flow around conducting/Janus cylinder was numerically studied in a confined |U-shaped microchannel with suddenly applied DC weak electric filed. It’s found that there are four large circulations around the conducting cylinder and two smaller circulations around the Janus cylinder. The results show that samples can still be well mixed with high flux due to the induced electroosmosis. It is demonstrated that the local flow circulations provide effective means to enhance the flow mixing between different solutions. The dependence of the degree of mixing enhancement on the electric field is also predicted

    Induced-charge electroosmosis around conducting and Janus cylinder in microchip

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    The induced-charge elecetroosmosis around conducting/Janus cylinder with arbitrary Debye thickness is studied numerically, when an direct current weak electric filed is suddenly applied in a confined microchannel. It’s found that there are four large circulations around the conducting cylinder, and the total flux in the microchannel is zero; there are two smaller circulations around the Janus cylinder, and they are compressed to wall. A bulk flux, which has a parabolic relation with the applied electric field, is also predicted

    Frost Durability and Strength of Concrete Prepared with Crushed Sand of Different Characteristics

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    The influences of fines content, methylene blue (MB) value, and lithology of crushed sand (CS) on frost durability and strength of concrete were investigated, and the frost durability and strength of crushed sand concrete (CSC) and river sand concrete (RSC) were compared. The results show that inclusion of fines improves CSC compressive strength and reduces frost durability of C30 CSC when fines content reaches 10%, whereas it has little negative influence on frost durability of C60 CSC. Increasing MB value does not negatively affect compressive strength of C30 CSC but decreases compressive strength of C60 CSC and frost durability of CSC, and the reduction is more pronounced when MB value exceeds 1.0. Lithology has no prominent influence on frost durability and compressive strength of CSC within the lithologies (dolomite, limestone, granite, basalt, and quartz) studied. Though compressive strength of CSC is a little higher than RSC under equal water to cement ratio, frost durability of CSC is no better than RSC especially for C30 CSC, and air-entraining agent is suggested for enhancing frost durability of C30 CSC exposed to freezing environment

    7-Chloro-5-(2-ethoxy­phen­yl)-1-methyl-3-propyl-2,6-dihydro-1H-pyrazolo[4,3-d]pyrimidine

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    In the title compound, C17H21ClN4O, the benzene ring is oriented at dihedral angles of 1.59 (3) and 1.27 (3)° with respect to the pyrimidine and pyrazole rings, while the dihedral angle between the pyrimidine and pyrazole rings is 0.83 (3)°. An intra­molecular N—H⋯O hydrogen bond results in the formation of a planar (r.m.s. deviation 0.004 Å) six-membered ring

    Modular generation of fluorescent phycobiliproteins

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    Phycobiliproteins are brightly-fluorescent light-harvesting pigments for photosynthesis in cyanobacteria and red algae. They are also of interest as fluorescent biomarkers, but their heterologous generation in vivo has previously required multiple transformations. We report here a modular approach that requires only two DNA segments. The first codes for the apo-protein. The second codes for fusions capable of chromophore biosynthesis and its covalent attachment to the apo-protein; it contains the genes of heme oxygenase, a bilin reductase, and a chromophore lyase. Phycobiliproteins containing phycoerythrobilin (lambda(fluor) similar to 560 nm), phycourobilin (lambda(fluor) similar to 500 nm), phycocyanobilin (lambda(fluor) similar to 630 nm) or phycoviolobilin (lambda(fluor) similar to 580 nm) were obtained in high yield in E. coli. This approach facilitates chromophorylation studies of phycobiliproteins, as well as their use for fluorescence labeling based on their high fluorescence
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