In this paper, a Pearson’s correlation coefficient based decision tree (PCC-Tree) is established and its parallel implementation is developed in the framework of Map-Reduce (MR-PCC-Tree). The ...proposed methods employ Pearson’s correlation coefficient as a new measure of feature quality to confirm the optimal splitting attributes and splitting points in the growth of decision trees. Besides, the proposed MR-PCC-Tree adopts Map-Reduce technology to every component during the decision trees learning process for parallel computing, which mainly consists of a parallel Pearson’s correlation coefficient based splitting rule and a parallel splitting data method. The experimental analysis is conducted on a series of UCI benchmark data sets with different scales. In contrast to several traditional decision tree classifiers including BFT, C4.5, LAD, SC and NBT on 17 data sets, the proposed PCC-Tree is no worse than the traditional models as a whole. Furthermore, the experimental results on other 8 data sets show the feasibility of the proposed MR-PCC-Tree and its good parallel performance on reducing computational time for large-scale data classification problems.
In the era of e-commerce economy, how to mine and study the different values of customers is an essential factor affecting the development of e-commerce enterprises. Based on this, this paper uses a ...clustering algorithm to mine and study the value of e-commerce customers. The research firstly constructs RFM e-commerce customer value identification framework, designs e-commerce customer value evaluation indexes and calculates the weights of the value indexes, and then uses K-means clustering algorithm and classical artificial bee colony algorithm to improve the Calculation, and completes e-commerce customer refinement based on the value of the user. The results show that the type of e-commerce customer value based on the RFMC model can be divided into eight types, based on which the e-commerce customer value is further subdivided into four types by using the clustering algorithm, namely, core customers (13.86%), supportive customers (45.38%), habitual customers (21.08%) and risky customers (19.68%). Based on the clustering algorithm, the customer value was classified into type 0 customers (low value customers), type 1 customers (high value customers), and type 2 customers (medium value customers).
Nanocomposites, multiphase solid materials with at least one nanoscaled component, have been attracting ever‐increasing attention because of their unique properties. Graphene is an ideal filler for ...high‐performance multifunctional nanocomposites in light of its superior mechanical, electrical, thermal, and optical properties. However, the 2D nature of graphene usually gives rise to highly anisotropic features, which brings new opportunities to tailor nanocomposites by making full use of its excellent in‐plane properties. Here, recent progress on graphene/polymer nanocomposites is summarized with emphasis on strengthening/toughening, electrical conduction, thermal transportation, and photothermal energy conversion. The influence of the graphene configuration, including layer number, defects, and lateral size, on its intrinsic properties and the properties of graphene/polymer nanocomposites is systematically analyzed. Meanwhile, the role of the interfacial interaction between graphene and polymer in affecting the properties of nanocomposites is also explored. The correlation between the graphene distribution in the matrix and the properties of the nanocomposite is discussed in detail. The key challenges and possible solutions are also addressed. This review may provide a constructive guidance for preparing high‐performance graphene/polymer nanocomposite in the future.
Recent progress on graphene/polymer nanocomposites is reviewed, with emphasis on strengthening and toughening, electrical conduction, thermal transportation, and photothermal conversion. The roles of graphene configuration, interfacial interaction, and distribution of graphene in the polymer to determine the properties of the nanocomposites are systematically explored. This may provide constructive guidance to develop high‐performance nanocomposites in the future.
The factors influencing tourist loyalty are widely highlighted in the literature. However, we find that the relationship between some influencing factors and loyalty is still inconsistent, and we ...don't yet know the strength and magnitude of the relationships. To address this issue, this study examined a meta-analysis of the five factors (satisfaction, motivation, perceived value, perceived quality, and experience quality) influencing tourist loyalty and its sub-dimensions.
The samples included articles from major academic databases, including Web of Science, Wiley Online, EBSCO, SAGE, Taylor and Francis, and Elsevier. Studies written in Chinese were retrieved from CNKI.com. We used the following keywords for retrieval: loyalty, behavioral intention, recommendation intention, word-of-mouth, revisit intentions, intention to revisit, willingness to recommend, and similar related terms. Conceptual and empirical studies published between January 1989 and September 2021 were extracted. To test whether there was publication bias, we used Fail-Safe-Number (FSN) to verify the stability of the results. The homogeneity test of the selected statistical model was based on the Q test and I2. The results were obtained by combining multiple single effect values into the combined effect value.
We developed 21 hypotheses and proposed a theoretical framework and analyzed 114650 accumulated sample sizes from 242 independent empirical studies. Among the 21 hypotheses proposed in this paper, the remaining 20 hypotheses have been proved except for hypothesis H6.
The findings showed that the five factors had varying degrees of positive and significant relationships with tourist loyalty and its sub-dimensions. In the descending order of effects, the five factors are degree of satisfaction, quality of experience, perceived value, perceived quality and motivation. We discussed the significance of the meta-analysis, theoretical and practical implications for destination marketing.
•Ultrasound pretreatment enhanced the phenolics content of mung bean sprouts.•Phenolics content and antioxidant capacity of mung bean sprouts positively correlated.•A total number of 608 metabolites ...were detected in sprouted mung beans.•More than 50 phenolic compounds were identified in sprouts of mung bean.•Sprouted mung bean digest showed high phenolics content and antioxidant capacity.
Mung bean seeds were treated by a combination of ultrasound and γ-aminobutyric acid (GABA). Effect of these treatments on the free polyphenols content, antioxidant activity, and digestibility of mung bean sprouts was evaluated. Additionally, phenolic compounds were analyzed and identified using a metabolomics approach. The combined ultrasound and GABA treatments significantly enhanced the free polyphenols and flavonoids content (P < 0.05) of mung bean sprouts depending on sprouting duration. Besides, a positive correlation (P < 0.05) was found between the polyphenols content and in vitro antioxidant activity of mung bean sprouts. Moreover, a total number of 608 metabolites were detected, and 55 polyphenol compounds were identified, including flavonoids, isoflavones, phenols, and coumarins. Also, the KEGG metabolic pathway analysis revealed 10 metabolic pathways of phenols, including flavonoid, isoflavone, and phenylpropanoid biosynthesis. Powder of 48 h sprouted mung bean released polyphenols during simulated gastric digestion and possessed antioxidant activity.
In the present work, influence of silane solution concentration on mechanical, tribological and morphological properties of Corn Stalk Fiber (CSF) reinforced polymer composites was investigated. ...Experimental results showed that the silane-treated CSF reinforced polymer composite (CMS) exhibited a promising property of low density. Silane solution treatments of the CSF could effectively reduce the water absorption and apparent porosity of the polymer composite system. The silane-treated CSF could not effectively improve the friction performance, but could significantly improve the wear rate of the polymer composites. Especially, the sum wear rate of 5% silane-treated CSF reinforced composite (5% CMS) decreased by 22.8% from 4.792 × 10−7 cm3(N⋅m)−1 to 3.699 × 10−7 cm3(N⋅m)−1 compared with that of the raw CSF reinforced composite (CMU), showing the best wear resistant behavior. Worn surfaces were examined by Scanning Electron Microscopy and the results revealed that the silane-treated CSF was conducive to the formation of secondary plateaus on the polymer composite surface, which could obviously improve the tribological and morphological properties.
•Corn stalk fibers were treated by the silane with the aim of develop bio-polymer composites.•The effect of surface treatment on tribological properties of the composites is confirmed.•Silane-treated corn stalk fibers were more effective in improving tribological properties.•Silane-treated corn stalk fibers were attributed to secondary plateaus on the worn surface.
Research has shown that mindfulness can reduce students' negative emotions associated with high-stakes tests and thereby improve test performance. This study explored the association between ...mindfulness-based intervention (MBI) and high-risk math test scores of middle school students, which is noticeably slim in the domain of mathematics education, through a mediating process involving math-specific test anxiety and math self-efficacy. Using data from a sample of 45 students, age 12-13, we found empirical support for a significant positive correlation between mindfulness and middle school students' math achievement. Participants listened to a mindfulness audio every other week before a mathematics test. Weekly mathematics test scores, student group discussion data, and in-depth interview data were analyzed to explore how mindfulness affected students' mathematics test performance, which showed a statistically significant improvement after mindfulness compared to mathematics achievement without the intervention. Our results indicate that mindfulness can relieve mathematics anxiety symptoms, including physiological manifestations, test-unrelated thinking and worries, and problem-solving obstacles caused by mathematics anxiety. Also, mindfulness, especially its non-judgmental attitude, positively affects students' mathematical self-efficacy. The current research provides evidence of the mindfulness intervention's efficacy for improving middle school mathematics test performance but also identifies the complexities of implementing it with large numbers of students.
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•g-C3N4 was immobilized on ATP by a facile freeze drying-calcination method.•The defects N sites from g-C3N4 attributed to the enhanced Cd(II) adsorption.•The saturated g-C3N4/ATP was ...converted to CdS/g-C3N4/ATP for photocatalysis.
Here we report a graphitic-C3N4 (g-C3N4) modified ATP adsorbent, g-C3N4/ATP, to enhance the adsorption of Cd(II) ion in wastewater, and the as-prepared adsorbent could be recovered as a CdS/g-C3N4/ATP photocatalyst utilized for the degradation of antibiotic pollutant. Due to the surface defects of g-C3N4 caused by the tri-s-triazine (C6N7) units, ATP could be bounded with g-C3N4 strongly. The combined adsorption sites, that the surface hydroxyl on ATP and the defected N sites on g-C3N4 attributed to the enhanced Cd(II) adsorption on g-C3N4/ATP hybrid (CA-0.50), which was 61.1 mg·g−1 and reached to the 1.76 times of that on the raw ATP. Meanwhile, due to the flexible structure of g-C3N4, the g-C3N4/ATP hybrid possessed a three-dimensional structure, and favored to improve the stability of adsorption by locking the adsorbed Cd(II). The Cd(II) adsorption on g-C3N4/ATP was well fitted the Langmuir isotherms model and exhibited the monolayer adsorption. For the recovered CdS/g-C3N4/ATP composite, it exhibited an excellent performance in the photodegradation of tetracycline with low concentration (25 ppm), on which the mineralization efficiency of tetracycline reached to 59.7% in 15 min under simulated solar light irradiation.
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•We found the selective catalytic performance of Co2+ and Mn2+ in sulfite oxidation.•The features of the solid sulfites were characterized and compared.•We elucidate the selective ...catalytic behavior by the position-occupying hypothesis.
Wet flue gas desulfurization (WFGD) has been widely used to reduce the harmful effects of sulfur dioxide during coal combustion, of which sulfite is a byproduct. Recycling this desulfurization byproduct requires the oxidation of sulfite, and transition metals might considerably promote the sulfite oxidation rate. We compared the oxidation rates of four sulfites—sodium sulfite, ammonium sulfite, magnesium sulfite, and calcium sulfite—and found that transition metals have selective catalytic performance. Although each transition metal was confined to specific sulfites, Co2+ and Mn2+ were the most effective catalysts. In addition, the sensitivity levels of the sulfite oxidation rates to various transition metals were classified. The orders of the reactions of the four sulfites catalyzed by Co2+ and Mn2+ were calculated. Although both magnesium sulfite and calcium sulfite exist as solids, the oxidation rate of magnesium sulfite was considerably sensitive to Co2+. The same results were observed for sodium sulfite and ammonium sulfite. However, the oxidation rate of calcium sulfite was sensitive only to Mn2+. The properties of the two prepared solid samples, magnesium sulfite and calcium sulfite, were compared using X-ray diffraction, scanning electron microscopy, and particle size analysis. The position-occupying hypothesis was applied to determine the selective catalytic behaviors of transition metals for the oxidation of various sulfites by comparing the ionic potentials of the metals. The results provide an effective theoretical basis for catalyzing the sulfite oxidation in WFGD.
Hold-downs have a dominant role in the force transmission of a cold-formed steel (CFS) structure, and their mechanical properties have a significant impact on the lateral resistance of the structure. ...Therefore, a total of 24 specimens of four types of hold-downs were designed and tested, focusing on the impacts of the number of anchor bolts and loading modes on the mechanical behaviour of hold-downs. The test results show that (1) the bending capacity of steel plates, the strength of weld joints, the arrangement of anchor bolts, and the load conditions are the key factors that determine the failure modes and damage degree of hold-downs. Moreover, the load–displacement relationship of hold-downs has obvious nonlinear characteristics. (2) The load and resistance factor design (LRFD) load capacities of the hold-downs significantly decrease with an increase in repeated deformation times. When assessing the load-bearing capacity of a CFS structure during the whole service period, the definition of LRFD load capacities of the hold-downs recommended in AISI S913-13 is conservative. Furthermore, an improved mechanical analysis model of a CFS shear wall that reflects the real mechanical characteristics of hold-downs was established by modifying the commonly utilized equivalent bracing model, and the effectiveness of the model was verified according to previous experimental results. The results confirm that the improved model adequately reflects the anchorage degradation of hold-downs and its influence on the shear properties of a wall, providing a more reliable modelling method for the collapse capacity assessment of CFS structures.
•A total of 24 hold-down specimens were designed and tested.•The key factors influencing the mechanical properties of hold-downs were explored.•An improved mechanical analysis model of a CFS shear wall was established and verified.
