Mining frequent sequences using itemset-based extension

In this paper, we systematically explore an itemset-based extension approach for generating candidate sequence which contributes to a better and more straightforward search space traversal performance than traditional item-based extension approach. Based on this candidate generation approach, we present FINDER, a novel algorithm for discovering the set of all frequent sequences. FINDER is composed oftwo separated steps. In the first step, all frequent itemsets are discovered and we can get great benefit from existing efficient itemset mining algorithms. In the second step, all frequent sequcnces with at least two frequent itemsets are detected by combining depth-first search and item set-based extension candidate generation together. A vertical bitmap data representation is adopted for rapidly support counting reason. Several pruning strategies are used to reduce the search space and minimize cost of computation. An extensive set ofexperiments demonstrate the effectiveness and the linear scalability of proposed algorithm

Intrinsic quadrupole moment of the nucleon

We address the question of the intrinsic quadrupole moment Q_0 of the nucleon in various models. All models give a positive intrinsic quadrupole moment for the proton. This corresponds to a prolate deformation. We also calculate the intrinsic quadrupole moment of the Delta(1232). All our models lead to a negative intrinsic quadrupole moment of the Delta corresponding to an oblate deformation.Comment: 17 pages, 5 figure

Exo-hydrogenated Single Wall Carbon Nanotubes

An extensive first-principles study of fully exo-hydrogenated zigzag (n,0) and armchair (n,n) single wall carbon nanotubes (C$_n$H$_n$), polyhedral molecules including cubane, dodecahedrane, and C$_{60}$H$_{60}$ points to crucial differences in the electronic and atomic structures relevant to hydrogen storage and device applications. C$_n$H$_n$'s are estimated to be stable up to the radius of a (8,8) nanotube, with binding energies proportional to 1/R. Attaching a single hydrogen to any nanotube is always exothermic. Hydrogenation of zigzag nanotubes is found to be more likely than armchair nanotubes with similar radius. Our findings may have important implications for selective functionalization and finding a way of separating similar radius nanotubes from each other.Comment: 5 pages, 4 postscript figures, Revtex file, To be appear in Physical Review

Long-menu questions in computer-based assessments: a retrospective observational study

Background: Computer based assessments of paediatrics in our institution use series of clinical cases, where information is progressively delivered to the students in a sequential order. Three types of formats are mainly used: Type A (single answer), Pick N, and Long-menu. Long-menu questions require a long, hidden list of possible answers: based on the student's initial free text response, the program narrows the list, allowing the student to select the answer. This study analyses the psychometric properties of Long-menu questions compared with the two other commonly used formats: Type A and Pick N. Methods: We reviewed the difficulty level and discrimination index of the items in the paediatric exams from 2009 to 2015, and compared the Long-menu questions with the Type A and Pick N questions, using multiple-way analyses of variances. Results: Our dataset included 13 exam sessions with 855 students and 558 items included in the analysis, 212 (38 %) Long-menu, 201 (36 %) Pick N, and 140 Type A (25 %) items. There was a significant format effect associated with both level of difficulty (p = .005) and discrimination index (p < .001). Long-menu questions were easier than Type A questions(+5.2 %; 95 % CI 1.1–9.4 %), and more discriminative than both Type A (+0.07; 95 % CI 0.01–0.14), and Pick N (+0.10; 95 % CI 0.05–0.16) questions. Conclusions: Long-menu questions show good psychometric properties when compared with more common formats such as Type A or Pick N, though confirmatory studies are needed. They provide more variety, reduce the cueing effect, and thus may more closely reflect real life practice than the other item formats inherited from paper-based examination that are used during computer-based assessments

Electro-oxidation competency of palladium nanocatalysts over ceria-carbon composite supports during alkaline ethylene glycol oxidation

Direct alcohol fuel cells (DAFCs) are widely regarded as one of the most promising among the futuristic and capable energy systems; direct liquid fuel cells (DLFCs). In this article, we discuss in detail the competency of palladium nanoparticles developed over carbon-ceria composite supports (Pd/C-CeO2) as efficient and durable anode catalysts for the alkaline electro-oxidation of ethylene glycol (EGOR). For the first time, a systematic assessment of the EGOR performance of palladium catalysts with varying Pd-ceria ratios has been reported. The scalable solid-solution route reduction technique enabled the processing of Pd nanoparticles with controlled morphology, size and excellent CeO2 interaction. The structural features of the prepared catalysts were studied using X-ray diffraction, electron microscopy (TEM) and X-ray photon spectroscopy techniques, while the electrochemical performance of the catalysts was analyzed using cyclic voltammetry and chronoamperometry. During alkaline EGOR, the Pd/C-CeO2 catalysts showed an enhanced current density (as high as 68.5 mA cm-2), more negative onset potential, excellent mass activity (4.6 A mg-1Pd) and exceptional durability compared to Pd/C. The enhanced alkaline EGOR kinetics of the Pd/C-CeO2 catalysts is well attributed to the promotion effect of CeO2 on Pd by creating more Pd-OHads and also improved tolerance to poisoning species on the Pd surface. Further, the enhanced ECSA of Pd/C-CeO2 has also aided the excellent EGOR activity in alkaline medium. The validated enhanced oxidation ability of these Pd/C-CeO2 catalysts for the anodic oxidation of other low molecular weight alcohol fuels including methanol and ethanol showcased their application potential toward DMFCs and DEFCs

Operation properties and δ-equalities of complex fuzzy sets

A complex fuzzy set is a fuzzy set whose membership function takes values in the unit circle in the complex plane. This paper investigates various operation properties and proposes a distance measure for complex fuzzy sets. The distance of two complex fuzzy sets measures the difference between the grades of two complex fuzzy sets as well as that between the phases of the two complex fuzzy sets. This distance measure is then used to define equalities of complex fuzzy sets which coincide with those of fuzzy sets already defined in the literature if complex fuzzy sets reduce to real-valued fuzzy sets. Two complex fuzzy sets are said to be d-equal if the distance between them is less than 1 d. This paper shows how various operations between complex fuzzy sets affect given δ-equalities of complex fuzzy sets. An example application of signal detection demonstrates the utility of the concept of δ-equalities of complex fuzzy sets in practice

A systematic study on the preparation and hydrogen storage of Zeolite 13X templated microporous carbons

Author's manuscript version.This is the pre-peer reviewed version of the following article: Yang, Z., Xiong, W., Wang, J., Zhu, Y. and Xia, Y. (2016), A Systematic Study on the Prep­aration and Hydrogen Storage of Zeolite 13X-Templated Microporous Carbons. European Journal of Inorganic Chemistry, which has been published in final form at doi: 10.1002/ejic.201501180.A systematic study on chemical vapour deposition (CVD)-based synthesis strategies (single CVD process, double CVD process and a combination of liquid impregnation and a CVD process) for the nanocasting of zeolite-templated porous carbon materials with commercially available zeolite 13X as hard template and ethylene, furfuryl alcohol, acetonitrile and/or vinyl cyanide as carbon precursor is presented. The results indicated that the combination of liquid impregnation and CVD is superior to the single or the double CVD processes in producing carbon materials with high surface area, high pore volume and high microporosity. The combination of liquid impregnation with furfuryl alcohol and CVD with ethylene generates carbon materials with the highest surface area of 2841 m2/g, a pore volume of 1.54 cm3/g and a hydrogen-uptake capacity of 6.3 wt.-% (at –196 °C and 20 bar). Under the studied conditions, the porous carbon materials exhibit variable structural ordering and tuneable textural properties with surface areas of 1600–2850 m2/g, pore volumes of 1.0–1.8 cm3/g and hydrogen-uptake capacities in the range of 3.4–6.3 wt.-% (at –196 °C and 20 bar). Notably, linear relationships between the hydrogen-uptake capacity and the total surface area, the micropore volume and the micropore surface area were found for the studied porous carbons, and this implies an important role of the total surface area, the micropore volume and the micropore surface area in the hydrogen adsorption.Royal SocietyRoyal Academy of EngineeringBayu Oversea Intelligence Plan of Chongqin