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Search Results: 1 - 10 of 104398 matches for " Xiaomei Zhang "
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Global Analysis of an SEIR Epidemic Model with a Ratio-Dependent Nonlinear Incidence Rate  [PDF]
Xiaomei Ren, Tiansi Zhang
Journal of Applied Mathematics and Physics (JAMP) , 2017, DOI: 10.4236/jamp.2017.512188
Abstract: In this paper, a SEIR model with ratio-dependent transmission rate in the form \"\"?is studied and the basic reproduction number which determines the disease’s extinction or continued existence is obtained. By constructing the proper Lyapunov function, we prove that if R0 ≤ 1, the disease-free equilibrium point of the model is globally asymptotically stable and the disease always dies out; if R0 > 1, the endemic equilibrium point is globally asymptotically stable and the disease persists.
The Effectiveness of the Flipped Classroom Mode on the English Pronunciation Course  [PDF]
Hongwei Zhang, Xiaomei Du, Xinfa Yuan, Liming Zhang
Creative Education (CE) , 2016, DOI: 10.4236/ce.2016.79139
Abstract: A lot of problems in pronunciation teaching remain unsolved after many years of efforts made by both teachers and researchers. This study is to research into the effectiveness of a comparatively new teaching mode—the flipped classroom—in the English pronunciation course. Mixed methods are adopted in this study in order to seek sufficient evidences for the effectiveness of the flipped classroom teaching mode. The students’ final exam scores are compared with those of the students taught with the traditional teaching mode. And individual face-to-face interviews are carried out to investigate the students’ attitudes towards the teaching modes. Finally, the conclusion is made that the flipped classroom mode is more effective than the traditional mode in pronunciation teaching.
The Permanence in a Single Species Nonautonomous System with Delays and Feedback Control
Xiaomei Feng,Fengqin Zhang
Discrete Dynamics in Nature and Society , 2010, DOI: 10.1155/2010/195983
Abstract: We consider a single species nonautonomous system with delays and feedback control. A general criterion on the permanence for all positive solutions is established. The results show that the feedback control does not influence the permanence of species.
The Effect of Temperament on Emotion Regulation among Chinese Adolescents: the Role of Teacher Emotional Empathy
Xiaomei Shen,Wenhai Zhang
International Education Studies , 2012, DOI: 10.5539/ies.v5n3p113
Abstract: Hierarchical linear modeling techniques were used to explored individual and contextual factors of emotion regulation in a sample of 2074 adolescents from grade 7 through grade 12 and 54 head teachers in China mainland. Emotion Regulation Questionnaire (ERQ) and Early Adolescent Temperament Questionnaire-Revised (EATQ-R) were administered among students and Multi-Dimensional Emotional Empathy Scale (MDEES) among head teachers. Results showed that at the student level, Effortful Control and Affiliativeness were positively related to adolescents’ reappraisal whereas Surgency was inversely correlated with reappraisal after gender, grade level and parent’s education were controlled. And Negative Affect (NA) positively predicted suppression. At the teacher level, teachers’ Emotional Contagion promoted the impact of adolescent Surgency on reappraisal after teaching age was controlled. In addition, Responsive Crying, Emotional Attention and Feeling for Others enhanced the influence of NA upon Suppression among teachers. However, Positive Sharing weakened the negative association between NA and Suppression. These findings expand the understanding of the role of teacher empathy in adolescents’ emotional development, and have important implications for classroom management and teacher empathy training.
Testing the Equality Hypothesis on a Cross-Covariance Matrix  [PDF]
Xiaomei Chen, Shibin Zhang
Open Access Library Journal (OALib Journal) , 2019, DOI: 10.4236/oalib.1105584
This paper is concerned about testing whether a cross-covariance matrix deviates from a pre-assigned one or not. For this purpose, a new test statistic is constructed based on the Frobenius norm of the difference between the sample cross-covariance matrix and the pre-assigned matrix. The test is implemented by applying the parametric bootstrap scheme. We conduct a simulation study to examine the performance of the test and compare it with other competitive tests. As multiple simulation examples show, our empirical powers are clearly superior to others in detecting any deviation of the cross-covariance from the pre-assigned matrix. In addition, the proposed test is insensitive to non-cross-covariance elements in the covariance matrix. As an illustration, we also investigate its performance in testing pairwise time-reversibility.
Characterization and Synthesis Mechanism of Nanosilver/PAMPS Composites by Microwave  [PDF]
Guocai Xu, Shengtao Gao, Xiaoli Ji, Xiaomei Zhang
Soft Nanoscience Letters (SNL) , 2014, DOI: 10.4236/snl.2014.42003
Abstract: Nanosilver/Poly(2-acrylamido-2-methylpropanesulfonate sodium (AMPS)) composites were synthesized with sliver nitrate solution containing AMPS monomer in situ by microwave radiation without addition of any reducer. The composites were characterized by means of UV-Vis, XRD, FTIR, TEM and XPS respectively. The results show that silver nanoparticles are dispersed highly and homogeneously in PAMPS matrix and possessed face-centered cubic structure. The morphology of nanosilver particles is not affected by microwave treatment and AMPS polymerization. XPS analysis reveals that there is an interaction among silver nanoparticles with nitrogen atoms and carbonyl oxygen atoms from AMPS polymer. Thermoanalysis proves that thermal stability of the PAMPS nanocomposites is decreasing with silver nanoparticles dispersed in the composites. The mechanism of silver ion reduced to nanosilver particles catalysized by PAMPS under microwave is discussed.
Antioxidant Activity in Vitro of Polysaccharide Extracted by Ultrasound with Different Powers from Ophiopogon japonicas  [PDF]
Xiaomei Wang, Tianzhu Zhang, Wenfei Zhang, Mingming Zhang, Songqi Zhu, Haibo Liu
American Journal of Plant Sciences (AJPS) , 2018, DOI: 10.4236/ajps.2018.99133

The polysaccharides were extracted by different power ultrasound from Ophiopogon japonicas. The extraction yield and in vitro antioxidant activities including scavenging effect on hydroxyl radical, superoxide anion free radicals and DPPH were investigated. The results showed that with the increase of ultrasonic power, the yield of the polysaccharides decreased first and then increased. The antioxidant activity of polysaccharides increased first and then decreased with the increase of ultrasonic power. When the power was 400 W, the scavenging effect on superoxide anion and DPPH of the polysaccharides was the strongest, and the scavenging ability of hydroxyl radical was the strongest when the power was

Morphology and Thermal Characteristics of Polysaccharide Extracted by Ultrasound from Ophiopogon japonicas  [PDF]
Xiaomei Wang, Tianzhu Zhang, Wenfei Zhang, Miao Wang, Dapeng Hao, Qi Ding
American Journal of Plant Sciences (AJPS) , 2018, DOI: 10.4236/ajps.2018.98123
Abstract: The crude polysaccharide UPOJ was extracted by ultrasound from Ophiopogon japonicas and purified by DEAE-cellulose52 column and Sephadex G-150 gel column. Purified polysaccharide UPOJ-DS was obtained. The thermal characteristics of UPOJ-DS were studied by using the thermal analysis system Q1000DSC LNCS FACS Q600SDT. The heating rate was 10°C/min and the test temperature was 20°C ~ 800°C. The results showed that there were three large mass losses in the process of heating, in which the maximum weight loss rate was 66.68% at 220°C ~
Complexity Analysis of Mixed Constraint Satisfaction Problems  [PDF]
Xiaomei Shi
Open Journal of Applied Sciences (OJAppS) , 2017, DOI: 10.4236/ojapps.2017.74011
Abstract: This paper analyzes the resolution complexity of a random CSP model named model RBmix, the instance of which is composed by constraints with different length. For model RBmix, the existence of phase transitions has been established and the threshold points have been located exactly. By encoding the random instances into CNF formulas, it is proved that almost all instances of model RBmix have no tree-like resolution proofs of less than exponential size. Thus the model RBmix can generate abundant hard instances in the threshold. This result is of great significance for algorithm testing and complexity analysis in NP-complete problems.
Global Sufficient Optimality Conditions for a Special Cubic Minimization Problem
Xiaomei Zhang,Yanjun Wang,Weimin Ma
Mathematical Problems in Engineering , 2012, DOI: 10.1155/2012/871741
Abstract: We present some sufficient global optimality conditions for a special cubic minimization problem with box constraints or binary constraints by extending the global subdifferential approach proposed by V. Jeyakumar et al. (2006). The present conditions generalize the results developed in the work of V. Jeyakumar et al. where a quadratic minimization problem with box constraints or binary constraints was considered. In addition, a special diagonal matrix is constructed, which is used to provide a convenient method for justifying the proposed sufficient conditions. Then, the reformulation of the sufficient conditions follows. It is worth noting that this reformulation is also applicable to the quadratic minimization problem with box or binary constraints considered in the works of V. Jeyakumar et al. (2006) and Y. Wang et al. (2010). Finally some examples demonstrate that our optimality conditions can effectively be used for identifying global minimizers of the certain nonconvex cubic minimization problem.
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