ARTICLE | doi:10.20944/preprints201810.0356.v2
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: higher-mode surface waves; dispersion curves; morphological component analysis; Radon transform
Online: 17 October 2018 (09:00:53 CEST)
Extraction of high-resolution surface waves is essential in surface-wave survey. Because reflections usually interfere with surface waves on X component in a multicomponent seismic exploration, it is difficult to extract dispersion curves of surface waves. The situation goes more serious when the frequencies and velocities of higher-mode surface waves are close to those of PS-waves. A method for surface-wave extraction is proposed based on the morphological differences between reflections and surface waves. Frequency-domain high-resolution linear Radon transform (LRT) and time-domain high-resolution hyperbolic Radon transform (HRT) are used to represent surface waves and reflections respectively. Then, the sparse representation problem based on the morphological component analysis (MCA) is built and optimally solved to obtain high-fidelity surface waves. An advantage of our method is its ability to extract surface waves when their frequencies and velocities are close to those of reflections. Furthermore, results of synthetic and field examples confirm that the proposed method can attenuate the distortion of surface-wave dispersive energy caused by reflections, which contributes to extracting accurate dispersion curves.
ARTICLE | doi:10.20944/preprints202208.0545.v1
Subject: Social Sciences, Education Keywords: perceptions of organizational justice; organizational citizenship behavior; job burnout; mediating effects
Online: 31 August 2022 (10:39:58 CEST)
The purpose of this study was to explore the relationship between teachers' perception of organizational justice and organizational citizenship behavior and to reveal the mediating role of teacher job burnout between teachers' perception of organizational justice and organizational citizenship behavior. This study used a questionnaire to collect data from 857 teachers in 21 secondary schools in Chongqing, China. Through a series of hierarchical regression analyses, mediating effects tests, structural equation modeling tests, and dominance analyses, the findings consistently indicated that procedural justice was a positive predictor of organizational citizenship behavior, while teacher’s job burnout was a negative predictor of organizational citizenship behavior. In addition, the study results also indicated that job burnout had a significant mediating effect on the relationship between teachers' perceptions of organizational justice and organizational citizenship behaviors, particularly with the passion burnout and burnout of professional self-effectiveness.
ARTICLE | doi:10.20944/preprints202308.0396.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: salt stress; photosynthesis; antioxidant enzymes; ROS scavenging; Meyerozyma guilliermondii
Online: 4 August 2023 (12:38:03 CEST)
How to improve plant tolerance and yield under salt stress is critical for ensuring sufficient food supply since plant survival and agricultural productivity are both affected by salinity. Some evidence has showed that beneficial microorganisms have a high ability to improve plant salt tolerance and increase crop yield. But few studies were involved in effects of halotolerant yeasts on plants under salt stress. In this present research, Meyerozyma guilliermondii, a halotolerant yeast, was inoculated with tomato plants followed by salt treatment of four different NaCl concentrations (0, 100, 200, and 300 mM). Our results showed that inoculation of M. guilliermondii increased the chlorophyll biosynthesis and photosynthetic machinery effectiveness under salt stress, contributing to biomass accumulation. Under salt treatment of 300 mM NaCl, the yeast inoculation significantly increased ascorbate concentrations in leaves, yet showed no effects on levels of glutathione and proline. Antioxidant enzymes were affected differently by the yeast inoculation. It was found that the yeast inoculation increased superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities under 300, 100, and 200 mM NaCl, respectively. Total soluble sugar levels increased in inoculated tomato plant leaves; however, there were no significant differences between different NaCl concentrations. Under 300 mM NaCl, the yeast inoculation significantly decreased H2O2 levels and reduced malondialdehyde levels. All together, our results showed that halotolerant yeast M. guilliermondii inoculation might be a strong candidate for regulating tomato growth under salt stress by increasing ability to scavenge reactive oxygen species and chlorophyll intactness, and by strengthening photosynthetic machinery.
ARTICLE | doi:10.20944/preprints202306.1690.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: WC-Co powder; ultrasonic vibration assisted pressing process; finite element simulation; pressed billet density
Online: 23 June 2023 (13:23:35 CEST)
The ultrasonic vibration assisted pressing process can improve the fluidity, the uneven distribution of density and particle size of WC-Co powder. However, the microscopic mechanism of ultrasonic vibration on the powder remains unclear. In this paper, WC and Co particles are simulated by three-dimensional spherical models of two particle sizes with the aide of the secondary development of Python. At the same time, the forming process of powder at mesoscale is simulated in the virtue of the finite element analysis software ABAQUS. The influence of vibration amplitude on the fluidity, the filling density and the stress distribution of WC-Co powder is investigated when the ultrasonic vibration is applied to the conventional pressing process. From simulation results, the ultrasonic vibration amplitude has great influences on the density of the compact. With the increase of the ultrasonic amplitude, the compact density also increases gradually. At the initial stage of the compaction, the particles move violently under the action of ultrasonic vibration, the fluidity is obviously enhanced, the arch bridge effect between particles is destroyed, the fine particles quickly fill the pores between the large particles, which increase the density, and the residual stress in the billet decreases after the compaction. From the experimental results, the size distribution of the billet is more uniform, the elastic aftereffect is reduced, the dimensional instability is improved, and the density curves obtained by experiment and simulation are within a reasonable error range.
ARTICLE | doi:10.20944/preprints201702.0042.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: high volume fly ash, high fluidity concrete, early strength, field application
Online: 13 February 2017 (11:44:54 CET)
In the recent concrete industry, high fluidity concrete is being widely used for the pouring of dense reinforced concrete. Normally, in the case of high fluidity concrete, it includes high binder contents, so it is necessary to replace part of the cement through admixtures such as fly ash to procure economic feasibility and durability. This study shows the mechanical properties and field applicability of high fluidity concrete that using mass of fly ash as alternative materials of cement. The high fluidity concrete mixed with 50% fly ash was measured to manufacture concrete that applies low water/binder ratio to measure the mechanical characteristics as compressive strength and elastic modulus. Also, in order to evaluate the field applicability, high fluidity concrete containing high volume fly ash was evaluated that fluidity, compressive strength, heat of hydration and drying shrinkage of concrete.