Representations of Nature of Science in Selected Histories of Science in the Integrated Science Textbooks in China

This study aimed to examine the representations of nature of science (NOS) in the eight histories of science selected from three series of integrated science textbooks used in junior high school in China. Ten aspects of NOS were adopted in the analytical framework. It was found that NOS had not been well treated in the selected histories of science in the three series of science textbooks. Specifically, it was found that the empirical and inferential aspects were treated better than other aspects, and discrepancies existed among the three series of science textbooks and among the eight histories of science in terms of dealing with the target NOS aspects. Implications for addressing NOS in historical materials in science textbooks were discussed in the final part of this paper.     

Existence of equilibria in articulated bearings in presence of cavity

The existence of equilibrium solutions for a lubricated system consisting of an articulated body sliding over a flat plate is considered. Here we consider the case when cavity can occur.     

Distribution of Magnetization in the Vicinity of Point Defects in Ferromagnetics

The localized distributions of magnetization, which slowly decrease with distance in the vicinity of magnetic imperfections in homogeneously magnetized ferromagnetics, were calculated in this work. It is shown that, in the case of the slowest decrease with distance, such distributions of magnetization interact with the domain wall, according to a formula that differs from that for the energy of the interaction between the homogeneous magnetic defect and the domain wall. The potential of the interaction between such imperfections was obtained.     

Centers of symmetry in finite intersections of balls in Banach spaces

It is proved that a real Banach spaceX is aG-space (C _σ - space)if and only if the non-empty intersection of three balls with equal radii (any three balls) has a center of symmetry.     

FANN模型在金属矿冲击地压预测中的应用

金属矿山冲击地压是采矿工程中所涉及到的重大灾害之一.冲击地压的发生是由多方面因素造成的,具有动态和模糊性,在客观上属于一个复杂的非线性动力学过程,这使得冲击地压预测系统的数据处理不能按照常规的线性系统法进行处理.根据模糊神经网络理论,本文给出了多源信息融合的模糊人工神经网络(FANN)模型.通过具体工程应用,说明了本文分析模型的正确性和有效性.     

Reasoning about variation in the intensity of change in covarying quantities involved in rate of change

This paper extends work in the area of quantitative reasoning related to rate of change by investigating numerical and nonnumerical reasoning about covarying quantities involved in rate of change via tasks involving multiple representations of covarying quantities. The findings suggest that by systematically varying one quantity, an individual could simultaneously attend to variation in the intensity of change in a quantity indicating a relationship between covarying quantities. The results document how a secondary student, prior to formal instruction in calculus, reasoned numerically and nonnumerically about covarying quantities involved in rate of change in a way that was mathematically powerful and yet not ratio-based. I discuss how coordinating covariational and transformational reasoning supports attending to variation in the intensity of change in quantities involved in rate of change.     

Estimates of Derivatives in Sobolev Spaces in Terms of Hypergeometric Functions

Mathematical Notes - The paper deals with sharp estimates of derivatives of intermediate order $$k\le n-1$$ in the Sobolev space $$\mathring W^n_2[0;1]$$ , $$n\in\mathbb N$$ . The functions...     

ARIMA模型在新疆巴州梅毒疫情预测中的应用

搜集2008-2014年新疆巴音郭楞蒙古自治州(简称巴州)梅毒月发病数据,采用时间序列分解方法(Time Series Decomposition methods)探讨该地区梅毒月发病率的季节性,建立ARIMA(0,1,1)(1,0,1)_(12)时间序列模型,模型预测值的动态趋势与实际发病率基本吻合,平均绝对百分比误差MAPE=17.36,具有较高的预测精度,可以较好的预测短期内梅毒的变化趋势,为梅毒的预防控制措施提供可靠依据.     

Tests of ordered hypotheses in linkage in heredity

The asymptotic null distribution of the likelihood ratio test for two cases of ordered hypotheses in a particular genetic model is considered. A simple iterative process is proposed in order to get the restricted estimates. It is shown that both tests have asymptotically a chi-bar squared distribution and the same size. A simulation study is also conducted in order to compare the usual unrestricted test with the corresponding one of ordered hypotheses. Finally, the results are extended to some special cases.     

Application of particle swarm optimization in chaos synchronization in noisy environment in presence of unknown parameter uncertainty

In this paper, particle swarm optimization (PSO) is applied to synchronize chaotic systems in presence of parameter uncertainties and measurement noise. Particle swarm optimization is an evolutionary algorithm which is introduced by Kennedy and Eberhart. This algorithm is inspired by birds flocking. Optimization algorithms can be applied to control by defining an appropriate cost function that guarantees stability of system. In presence of environment noise and parameter uncertainty, robustness plays a crucial role in succeed of controller. Since PSO needs only rudimentary information about the system, it can be a suitable algorithm for this case. Simulation results confirm that the proposed controller can handle the uncertainty and environment noise without any extra information about them. A comparison with some earlier works is performed during simulations.     

Calculation of stresses in a coal seam in presence of gas diffusion

Analytical expressions are obtained for calculating the stresses in a coal seam in presence of gas diffusion. The solution is given as a sum whose four terms are convergent series. All functions in the relevant expressions can easily be computed either separately or successively; i.e., it is not required to solve infinite systems of equations.     

Comparison of the flow of viscoelastic media in shear and in tension

A geometrical method of comparing steady-state flow in uniaxial tension and in simple shear is proposed. This method is based on a comparison of the deformation regimes relative to the principal axes.     

Emergence of Self-Excited Oscillations in Flows of Inviscid Fluids in a Channel

Computational Mathematics and Mathematical Physics - The mechanism of self-excited oscillations arising in an ideal incompressible fluid flowing through a rectangular channel is studied...     

一类R^N上含散度型算子的椭圆方程的非径向对称解的存在性

本文中,我们利用变分方法研究了-div(a(hx)|u|p-2u)+|u|p-2u=g(x)f(u),)/(x∈RN,u(x)≥0,)/(x∈RN,u∈W1,p(RN),弱解的存在性.其中p＞N≥2,a与g是正的径向对称函数.我们主要得到该问题在一定条件下的非径向对称最小能量解的存在性,并且利用Ljusternik-Schnirelmann定理得到了一个与a相关的关于解的数量的结果.