173 research outputs found

    The Effects of Transformational Leadership on Employee’s Pro-social Rule Breaking

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    The construct of pro-social rule breaking occupies an important, but largely neglected position within exi-sting frameworks of organizational deviance Pro-social rule breaking (PSRB) is a form of constructive de-viance characterized by volitional rule breaking in the interest of the organization or its stakeholders.Usi-ng survey data collected from 252 employees in different organizations in China,the researchers empirically examines the relationship between transformational leadership and employee’s pro-social rule breaking and the mediating role of job autonomy. Results indicate that transformational leadership is positively rel-ated to pro-social rule breaking,job autonomy fully mediates the relationships between transformational le-adership and employee’s pro-social rule breaking. Theoretical and practical implications are discussed. A set of future research directions are offered

    Networked multiple approaches to developing functional thinking in elementary mathematics textbooks: a case study in China

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    By focusing on functional thinking (FT), the core component of algebraic thinking, this study aimed to explore the features of developing FT in textbooks from grades 1 to 6 by examining a popular reform-oriented mathematics textbook series in China. A framework of FT developed by Pittalis and colleagues (2020) was used to examine the FT related tasks in the textbook series. Based on a fine-grained coding analysis, it was found that multiple modes of FT are intended to be developed since the very beginning of elementary school. Multi-modes of FT have been developed and evolved simultaneously and progressively as grades increase, serving as an enhancement for arithmetic learning. Different types of FT tasks provide various opportunities for students to explore these multi-modes of FT while learning and consolidating arithmetic across grades

    Influence of fine particles on the stability of a humid granular pile

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    We have investigated by rotating drum experiments the influence of a small amount of fine particles on the stability of a granular heap. The fine particles are shown to have a strong and ambivalent influence. For low fine particle content, the heap destabilizes by avalanches, and the fine particles tend to fluidize the heap. In contrast, for high fine particle content, they increase the cohesion of the heap, which destabilizes through stick-slip at the drum wall. We interpret and model the fluidification in the avalanching regime, which we show is independent of humidity, by granular lubrication considerations, whereas the stick-slip behavior, highly dependent on humidity, is understood by a solid friction model

    Influence des particules fines sur la stabilité d'un milieu granulaire

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    L'objectif de ce travail est de comprendre l'influence des particules très fines sur le phénomène de ré-agglomération lors du broyage. Des billes de verre de taille 0 à 20 m avec un pourcentage massique variant entre 0 à 1% sont ajoutées dans un tas granulaire de billes de verre de 200 à 300 m dans un tambour tournant cylindrique de diamètre et longueur 10 cm. La présence des particules fines montre un effet ambivalent sur la stabilité du tas granulaire. Nous avons établi un diagramme de stabilité du milieu granulaire en fonction de la concentration de particules fines et cherché à quantifier l'effet des fines combiné avec d'autres paramètres (humidité relative et vitesse de rotation du tambour). La stabilité d'un tas granulaire dans un tambour tournant est déterminée par la mesure de son angle maximum de stabilité m. Dans un premier temps, nous avons étudié l'évolution de cet angle à des vitesses de rotation différentes. Les expériences montrent qu'à faible concentration (< 0; 15%), le tas se déstabilise par avalanches lorsque le tambour tourne, m diminue lorsqu'on augmente la quantité de fines. Quand la vitesse de rotation augmente, le mouvement du tas évolue du régime d'avalanche intermittent au régime d'écoulement continu. En revanche, lorsque la concentration des fines est supérieure à 0,15%, la déstabilisation du tas se traduit par un phénomène de stick-slip à la paroi du tambour, et la quantité de fines augmente la stabilité du tas. Ce comportement apparemment contradictoire est lié au fait que la localisation de la déstabilisation est modifiée. Dans le régime des faibles concentrations, les avalanches commencent à la surface du tas, et le remplissage de l'espace intermédiaire entre les grosses billes par les fines rend la surface de plus en plus lisse, ce qui déstabilise le tas. Par ailleurs, les fines induisent une augmentation de la cohésion du tas par la nucléation des ponts capillaires entre les grains. Ainsi, dans le régime des fortes concentrations, le tas granulaire se comporte comme un corps solide et la déstabilisation a lieu à l'interface tas-tambour. Nous avons également étudié l'influence de l'humidité relative sur la stabilité et montré que dans le régime de faible concentration de particules fines, la déstabilisation est indépendante de l'humidité. D'autre part dans le régime des hautes teneurs en fines, une humidité relative élevée induit une forte cohésion due à la condensation capillaire entre les grains et le tambour ce qui entraîne une augmentation de l'angle maximum de stabilité.The aim of this work is to understand the effect of very fine particles on the phenomenon of re-agglomeration in the grinding process. Various amount of fine glass beads of 0 to 20 m (0 to 1% mass concentration) are added to a granular pile of glass beads of 200 to 300 m rotated in a drum with inner diameter and length of 10 cm. The presence of fine particles shows an ambivalent effect on the stability of the granular heap. We established a stability diagram of the granular medium as a function of fine concentration and quantified the effect of fines combined with other parameters (relative humidity and rotation velocity). The stability of a granular heap in a rotating drum is determined by the measurement of the maximum angle of stability m. Firstly, we studied the evolution of this angle with different rotation velocities. The experiments indicate that at low fine concentration (< 0:15%), the heap destabilizes through avalanches when the drum rotates, and increasing the fine quantity tends to decrease m. When the rotation velocity increases, the granular medium transits from intermittent avalanche to continuous flow. In contrast, once the concentration is more than 0:15%, the destabilization of the heap proceeds through a stick-slip phenomenon at the drum wall, and the increase of the fraction of fines tends to increase the stability of the heap. This apparent contradictory behavior is linked to the modification of the destabilization location. In the small concentration regime, the avalanches start at the surface of the heap, and the filling of the interstitial space by the fine particles makes this surface smoother and smoother, thus destabilizing the heap. Besides, the fines induce, through the nucleation of capillary bridges between grains, an increase of the bulk cohesion of the heap. So in the large concentration regime, the heap behaves as a solid body and the destabilization occurs at its bottom. We also studied the influence of relative humidity on the granular stability in our experiment. We found out in the low fine concentration regime, the destabilization is independent of humidity. On the other hand, in the regime of high content of fines, high relative humidity induces a large cohesion due to the capillary condensation between the grains and the wall which induce the increase of the maximum stability angle.LYON-Ecole Centrale (690812301) / SudocSudocFranceF

    The Complex Dynamics of a Stochastic Predator-Prey Model

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    A modified stochastic ratio-dependent Leslie-Gower predator-prey model is formulated and analyzed. For the deterministic model, we focus on the existence of equilibria, local, and global stability; for the stochastic model, by applying Itô formula and constructing Lyapunov functions, some qualitative properties are given, such as the existence of global positive solutions, stochastic boundedness, and the global asymptotic stability. Based on these results, we perform a series of numerical simulations and make a comparative analysis of the stability of the model system within deterministic and stochastic environments

    Explosion risk assessment model for underground mine atmosphere

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    In the coal mining industry, explosions or mine fires present the most hazardous safety threats for coal miners or mine rescue members. Hence, the determination of the mine atmosphere explosibility and its evolution are critical for the success of mine rescues or controlling the severity of a mine accident. However, although there are numbers of methods which can be used to identify the explosibility, none of them could well indicate the change to the explosion risk time evolution. The reason is that the underground sealed atmospheric compositions are so complicated and their dynamical changes are also affected by various influence factors. There is no one method that could well handle all such considerations. Therefore, accurately knowing the mine atmospheric status is still a complicated problem for mining engineers. Method of analyzing the explosion safety margin for an underground sealed atmosphere is urgently desired. This article is going to propose a series of theoretical explosion risk assessment models to fully analyze the evolution of explosion risk in an underground mine atmosphere. Models are based on characteristics of the Coward explosibility diagram with combining mathematical analyzing approaches to address following problems: (1) for an "not-explosive" atmosphere, judging the evolution of explosion risk and estimating the change-of-state time span from "not-explosive" to "explosive" and (2) for an "explosive" atmosphere, estimating the "critical" time span of moving out of explosive zone and stating the best risk mitigation strategy. Such research efforts could not only help mine operators understand the explosibility risk of a sealed mine atmosphere but also provide a useful tool to wisely control explosive atmosphere away from any dangers. In order to demonstrate research findings, case studies for derived models are shown and are also used to instruct readers how to apply them. The results provide useful information for effectively controlling an explosive underground sealed atmosphere

    Effects of Hydrological and Climatic Variables on Cyanobacterial Blooms in Four Large Shallow Lakes Fed by the Yangtze River

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    Shallow lakes, one of the most widespread water bodies in the world, are easily shifted to a new trophic state due to external interferences. Shifting hydrologic conditions and climate change can cause cyanobacterial harmful algal blooms (CyanoHABs) in shallow lakes, which pose serious threats to ecological integrity and human health. This study analyzed the effects of hydrologic and meteorological variables on cyanobacterial blooms in Yangtze-connected lakes (Lake Dongting and Poyang) and isolated lakes (Lake Chao and Tai). The results show that (i) chlorophyll-a (Chl-a) concentration tends to decrease exponentially with increasing relative lake level fluctuations (RLLF) and precipitation, but to increase linearly with increasing wind speed and air temperature; (ii) Chl-a concentrations in lakes were significantly higher when RLLF \u3c 100, precipitation \u3c 2.6 mm, wind speed \u3e 2.6 m s−1, or air temperature \u3e 17.8 °C; (iii) the Chl-a concentration of Yangtze-isolated lakes was more significantly affected by water level amplitude, precipitation, wind speed and air temperature than the Yangtze-connected lakes; (iv) the RLLF and the ratio of wind speed to mean water depth could be innovative coupling factors to examine variation characteristics of Chl-a in shallow lakes with greater correlation than single factors

    Effect of Non-sodium Salt Substitution on the Properties and Flavor of Coix Starch-Myofibrillar Protein Composite Gel

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    Objective: To investigate the effect of calcium, magnesium and potassium salts on the properties of coix seed starch-myofibrillar protein (CSS-MP) composite gel with low sodium content. Methods: Based on the results of previous research, the effects of partial substitution of NaCl by CaCl2, MgCl2 or KCl on the gel strength, water holding capacity (WHC), rheological properties, surface hydrophobicity, sulfhydryl group content, gel microstructure and sensory evaluation of CSS-MP composite gel were investigated. Results: The texture and rheological properties of the CaCl2 substitution group were better than those of the control group (3% NaCl), and the WHC and whiteness of the KCl substitution group were not significantly different from those of the control group, but the gel strength was decreased by MgCl2 or KCl substitution. The total sulfhydryl content of the CaCl2 and MgCl2 replacement groups was significantly lower than that of the control group, and the surface hydrophobicity of the CaCl2 replacement group was significantly higher than that of the other three groups. The addition of MgCl2 promoted the formation of hydrogen bonds, enhanced the hydrophobic interaction, while CaCl2 substitution had the opposite effect. In terms of sensory properties, the substitution of 1.0% CaCl2 and 0.5% MgCl2 could attain a saltiness perception similar to 3% NaCl. However, the comprehensive sensory score showed that the substitution of the three chlorine salts caused no significant difference in sensory properties of CSS-MP composite gel. Conclusion: Calcium, magnesium and potassium salts can improve the properties of CSS-MP composite gel in different degrees. The results of this study lay a theoretical foundation for the development of low-sodium composite surimi gel products

    A multimodal fusion method for Alzheimer’s disease based on DCT convolutional sparse representation

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    IntroductionThe medical information contained in magnetic resonance imaging (MRI) and positron emission tomography (PET) has driven the development of intelligent diagnosis of Alzheimer’s disease (AD) and multimodal medical imaging. To solve the problems of severe energy loss, low contrast of fused images and spatial inconsistency in the traditional multimodal medical image fusion methods based on sparse representation. A multimodal fusion algorithm for Alzheimer’ s disease based on the discrete cosine transform (DCT) convolutional sparse representation is proposed.MethodsThe algorithm first performs a multi-scale DCT decomposition of the source medical images and uses the sub-images of different scales as training images, respectively. Different sparse coefficients are obtained by optimally solving the sub-dictionaries at different scales using alternating directional multiplication method (ADMM). Secondly, the coefficients of high-frequency and low-frequency subimages are inverse DCTed using an improved L1 parametric rule combined with improved spatial frequency novel sum-modified SF (NMSF) to obtain the final fused images.Results and discussionThrough extensive experimental results, we show that our proposed method has good performance in contrast enhancement, texture and contour information retention

    Microbiome and Metabolomics Reveal the Effects of Different Feeding Systems on the Growth and Ruminal Development of Yaks

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    The change in the feeding system can greatly improve the growth performance of the yak (Bos grunniens), an important livestock species in the plateau region. Here, we comprehensively compared the effects of different feeding systems on the growth performance and ruminal development of yaks, and investigated the effects of ruminal microorganisms and metabolites using the 16S rRNA gene sequencing and liquid chromatograph–mass spectrometer (LC-MS) technologies. We found that compared to traditional grazing feeding, house feeding significantly improved the growth performance (such as average daily gain and net meat weight) and rumen development of the yaks. At the genus level, the abundance of Rikenellaceae RC9 Gut group, Christensenellaceae R-7 group, Lachnospiraceae NK3A20 group, Ruminococcaceae UCG-014, and Prevotellaceae UCG-003 showed significant differences and was closely related to rumen development in the two distinct feeding systems. Also, metabolomics revealed that the change in the feeding system significantly affected the concentration and metabolic pathways of the related rumen metabolites. The metabolites with significant differences were significantly enriched in purine metabolism (xanthine, adenine, inosine, etc.), tyrosine metabolism (L-tyrosine, dopaquinone, etc.), phenylalanine metabolism (dihydro-3-caumaric acid, hippuric acid, etc.), and cAMP signaling pathway [acetylcholine, (-)-epinephrine, etc.]. This study scientifically support the house fattening feeding system for yaks. Also, our results provide new insights into the composition and function of microbial communities that promote ruminal development and in general growth of the yaks
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