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Extracting a subset of representative users from the original set in social networks plays a critical role in Social Network Analysis. In existing studies, some researchers focus on preserving users' characteristics when sampling representative users, while others pay attention to preserving the topology structure. However, both users' characteristics and the network topology contain abundant information of users. Thus, it is critical to preserve both of them while extracting the representative user subset. To achieve the goal, we propose a novel approach in this study, and formulate the problem as RUS (Representative User Subset) problem that is proved as an NP-Hard problem. To solve RUS problem, we propose two approaches KS (K-Selected) and an optimized method (ACS) that are both consisted of a clustering algorithm and a sampling model, where a greedy heuristic algorithm is proposed to solve the sampling model. In addition, we propose the pruning strategy by taking advantage of MaxHeap structure. To validate the performance of the proposed approach, extensive experiments are conducted on two real-world datasets. Results demonstrate that our methods outperform state-of-the-art approaches. [ABSTRACT FROM AUTHOR]

It is common that historical Tibetan documents belonging to historical collections are poorly preserved and are prone to degradation processes. This causes many challenges that can be addressed by image binarization, the most common of which is stains. A lack of uniform standard datasets makes it difficult to evaluate binarization effects. Motivated by the poor effects and difficulty of evaluating the binarization of historical Tibetan document images, a combined approach is proposed that aims to improve overall performance. The method includes the following parts: first, image generation through standard binarization and the background extraction of color images, which are both used for image synthesis in preparing for an evaluation. Then, preliminary binarization processing is implemented through channel combination in the lab color space and through local binarization. The synthetic images are used to select the coefficient when the channels are combined. Furthermore, Local Binary Pattern (hereafter LBP) and image smoothing is carried out after the combination of the channels to obtain the outline of the text area. Finally, the final binarization image is obtained by combining the preliminary binarization image and the text area contour image. Our method achieved top performance compared to other methods after a large number of synthetic image tests with a variety of background types. [ABSTRACT FROM AUTHOR]

The application of municipal solid waste incineration tailings lightweight aggregate (MSWI-TLA) for reducing carbon emissions, energy consumption, and environmental pollution of bulk solid waste treatment has received extensive attention. As a new type of green lightweight aggregate, MSWI-TLA exhibits considerably good performance and broad prospects; however, its working performance in cement-based materials is not as good as that of ordinary aggregates. In this study, a standardized municipal solid waste incineration tailings lightweight fine aggregate (MSWI-TLFA) with a fineness modulus of 3.1 and a municipal solid waste of 10 mm were utilized as substitutes for the common aggregate. The incineration tailings lightweight coarse aggregate (MSWI-TLCA) with the particle size ranging from 5 to stirring process and the fluidity and filling properties were improved, and stratification was slowed down. Based on the slump, fluidity, and stratification data of municipal solid waste incineration tailings lightweight aggregate specific density concrete (MSWI-TLA-SDC), the internal and external stacking structure model, matrix density three-phase diagram, and stratification function relationship were established, and the formation mechanism of fluidity and homogeneity under the synergistic effect of MSWI-TLA-SDC matrix density was revealed. Simultaneously, the qualitative analysis of homogeneity was carried out intuitively and visualized using computed tomography (CT) technology, and the accurate quantitative analysis model of stratification degree and aggregate separation factor was established using the principle of fluid mechanics, and the optimization effect was verified. The results show that the fluidity of MSWI-TLA-SDC decreases by 3.3%–30.5% and the delamination degree increases by 4.9%–22.9% compared with ordinary concrete. The main reason for the poor fluidity and homogeneity of MSWI-TLA-SDC is the poor density synergy between tailings lightweight aggregate, ordinary aggregate, and mortar matrix. The preabsorbed gravel-type small-size tailings lightweight aggregate along with technical measures like combining water-reducing agent, fine tailings aggregate, and tailings powder can be used to reduce the difference in matrix density and fully exploit the synergistic effects of matrix density. For the closed-loop absorption of tailings lightweight aggregate as well as the technical advancement and promotion of MSWI-TLA-SDC, it is crucial to increase the fluidity and homogeneity of MSWI-TLA-SDC. [ABSTRACT FROM AUTHOR]

The online handwriting recognition of Tibetan characters is still in its infancy. For further research, an online handwriting database of large Tibetan character set was developed, and a recognition research was carried out on this database as a baseline result. The Northwest Minzu University Online Tibetan Handwriting Database (NMU-OLTHWDB) contains 7240 different types of characters, and the sample number in each type is 5000. The total number of samples is 7 2 4 0 × 5 0 0 0. The database covers Tibetan Character Collection, Information Technology Tibetan Coded Character set (Extension Set A), and Information Technology Tibetan Coded Character set (Extension Set B). The characters in the database are composed of 170 types of different components. We studied the online handwritten Tibetan recognition software also, and the character feature extraction, classifier training, and the statistics and analysis of the recognition results on the test set were mainly introduced. The character features included the direction attribute coefficients and spatial combination, and the feature matrix was compressed by Linear Discriminate Analysis (LDA). A quick classifier was designed by a modified quadratic discriminate function (QMQDF), and was trained with 4500 sets of samples. In the large character set, the recognition rates of top 1, top 3, top 5, and top 10 were 75.2%, 89.56%, 93.02%, and 95.96%, respectively. Moreover, an online handwriting recognition system for Tibetan large character set was designed with good performance. [ABSTRACT FROM AUTHOR]

• The mechanical properties of specified-density concrete under static and dynamic compression were studied. • Specified-density concrete had superior dynamic mechanical properties. • The differences in the failure modes and mechanisms of specified-density and ordinary concrete were analyzed. • The dynamic increase factor (DIF) and an energy absorption model of specified-density concrete were established. • A dynamic constitutive model of specified-density concrete was established. As a green alternative building material for aggregates and admixtures in concrete, domestic waste incineration tailings recently have gained increasing attention from the scientific community, and can improve the sustainability of building materials. This paper studies the performance and mechanism of the specified density concrete reinforced by waste incineration tailings under dynamic impact, focusing on the influence of the dosage (25, 50 and 75 wt%) and the intermediate strain rate (20–80 s-1) of the incineration tailings, and the feasibility of using them as the lightweight aggregate in the specified density concrete. The results show that the failure morphology of the static and dynamic mechanical properties of the specified density concrete (SDC) is similar, and the failure crack passes through the weak interface between the tailing lightweight aggregate and the ordinary aggregate mortar. The addition of incineration tailings is conducive to improving the anti-impact properties of specified density concrete under intermediate strain rate. Due to the internal and external interlocking structure effect of aggregate, the dynamic increase factor (DIF) and energy absorption (ω s) of three types of specified density concrete (SDC-25, SDC-50 and SDC-75) are 79.6%∼99.1% and 1.09 ∼ 1.79 times higher than that of ordinary concrete respectively, and the degree of fragmentation, peak stress and peak strain are significantly improved. The dynamic constitutive equation of specified density concrete with good applicability is proposed and successfully applied to numerical calculation. Considering the engineering performance and potential economic benefits of specified density concrete, incineration tailings can be used as a sustainable and cost-effective substitute for some cement-based materials. [ABSTRACT FROM AUTHOR]