基于SPA理论的高中物理学科核心素养评价研究

对学生的物理学科核心素养进行科学评价是促进学生身心成长和发展的重要内容之一.文章基于SPA理论,定量评价了学生的物理学科核心素养.以学生月考试卷为研究对象,首先统计了全体学生学科核心素养各维度的得分情况;接着,利用基础及扩展的SPA算法对月考试卷进行了分析;最后对学生物理学科核心素养的各维度和总体进行评价和预测.通过研究表明,基于SPA理论的学生学科核心素养评价,不仅能对被测对象进行分维度和综合的量化评价,还具有一定预测的功能.     

原位法MgB_2-B_4C复相超导体合成及相含量调控研究

以B4C和Mg为原料合成的MgB2-B4C复相超导体具有高的临界电流密度(Jc)和高的超导转变温度(Tc),是一种有潜力的实用MgB2超导材料,其成相机理对复相MgB2超导体的相含量调控和磁通钉扎研究具有重要意义。结合经典烧结理论,研究了B4C-Mg真空固相烧结制备MgB2-B4C复相超导体的超导相形成和晶粒生长过程,给出了B4C-Mg的金斯特林格扩散模型和MgB2晶粒生长过程。通过选择B4C原料粒径,MgB2-B4C复相超导体超导相体积相含量在18%-88%范围可控。相含量88%的MgB2-B4C复相超导体临界转变温度达33.5K,转变宽度1.5K。10 K环境6T外场下电流密度可以达到1×104A/cm2,表明MgB2-B4C复相超导体具有良好的磁通钉扎行为。     

带强迫项变系数组合KdV方程的无穷序列复合型类孤子新解

为了获得变系数非线性发展方程的无穷序列复合型新解,研究了G′(ξ)G(ξ)展开法.通过引入一种函数变换,把常系数二阶齐次线性常微分方程的求解问题转化为一元二次方程和Riccati方程的求解问题.在此基础上,利用Riccati方程解的非线性叠加公式,获得了常系数二阶齐次线性常微分方程的无穷序列复合型新解.借助这些复合型新解与符号计算系统Mathematica,构造了带强迫项变系数组合KdV方程的无穷序列复合型类孤子新精确解.     

自动选取辅助目标的建筑物目标间接定位方法

针对序列图像中目标因不显著、被遮挡等情况而出现的虚警或丢失问题，提出一种基于自动选取辅助目标的建筑物目标间接定位方法，提高目标跟踪稳定性。该方法首先自动选取红外图像中形状稳定、灰度显著的区域作为辅助目标。定位建筑物目标后，提取其与目标相对位置关系, 之后利用该相对位置间接定位，最后融合直接识别及间接定位结果定位目标，并能实时更新辅助目标，保证其时刻处于视场中。实验结果表明:通过间接定位能解决目标虚警或丢失问题，提升目标定位过程中算法的准确性及鲁棒性。     

视觉掩盖效应下的无参考图像信噪比评价

针对噪声图像,提出一种视觉掩盖效应下的无参考图像信噪比评价方法。采用Hosaka分块思想,利用四叉树分解,取消了Hosaka分块对图像尺寸的限制,分块的大小体现出块内图像的主要频率成分;然后检测各个子块噪声,根据图像的污染程度,计算NRPSNR值。利用LIVE Database Release2图像库中的WN的174幅图像检验NRPSNR与DMOS的相关度,并与MSE、PSNR以及HVSNR比较分析。实验结果表明,该方法总体评价效果优于其他3种评价方法,CC为-0.895 0,SROCC为-0.923 6,OR为0.042 9,主客观评价比较吻合,且对于其他噪声类型同样适用,体现了人的视觉掩盖效应,可以满足对无参考噪声图像进行准确可靠的质量评价要求。     

开普勒三定律与地球公转轨道参数的讨论

分别从拉格朗日量、龙格-楞次矢量以及微分方程出发,由万有引力定律导出了开普勒三定律,并积分得到开普勒方程与轨道周期.利用文献中的数据计算了地球公转轨道的偏心率和周期,发现有的文献给出的地球近日点和远日点速率值使得计算结果和观测值之间存在较大的不一致.分析其原因并给出了速率的修正值,从而保证了计算结果和观测值之间的自洽性.     

Second to tenth order susceptibilities of conserved charges within a modified Nambu-Jona-Lasinio model

We discuss the sign and energy dependence of second to tenth order susceptibilities of the baryon number,charge number, and strangeness for the analysis of critical conditions in heavy ion collisions in the LHC and RHIC by applying a modified Nambu-Jona-Lasinio model. This model is fitted to the quark condensate of the lattice QCD result at finite temperature and zero baryon chemical potential. The presence of a critical point made these susceptibilities deviate considerably from a Hadron-Resonance-Gas model that shows no criticality. The sign, magnitude, and energy dependence of these higher order fluctuations hint towards the existence and location of a critical point that could be discovered in future heavy ion collision experiments.     

Finite volume effects on the QCD chiral phase transition in the finite size de-pendent Nambu-Jona-Lasinio model

The effective Lagrangian of a finite volume system should, in principle, depend on the system size. In the framework of the Nambu-Jona-Lasinio(NJL) model, by considering the influence of quark feedback on the effective coupling, we obtain a modified NJL model so that its Lagrangian depends on the volume. Based on the modified NJL model, we study the influence of finite volume on the chiral phase transition at finite temperature, and find that the pseudo-critical temperature of crossover is much lower than that obtained in the normal NJL model. This clearly shows that the volume dependent effective Lagrangian plays an important role in the chiral phase transitions at finite temperature.     

Anisotropic evolution of 4-brane in a 6D generalized Randall-Sundrum model

We investigate a 6 D generalized Randall-Sundrum brane world scenario with a bulk cosmological constant.Each stress-energy tensor T_(ab)~i on the brane is shown to be similar to a constant vacuum energy.This is consistent with the Randall-Sundrum model,in which each 3-brane Lagrangian yielded a constant vacuum energy.By adopting an anisotropic metric ansatz,we obtain the 5 D Friedmann-Robertson-Walker field equations.In a slightly later period,the expansion of the universe is proportional to the square root of time,t~(1/2),which is similar to the period of the radiation-dominated regime.Moreover,we investigate the case with two a(t) and two b(t).In a large range of t,we obtain the 3 D effective cosmological constant Λ_(eff)=-2Ω/30,which is independent of the integral constant.Here,the scale factor is an exponential expansion,which is consistent with our present observation of the universe.Our results demonstrate that it is possible to construct a model that solves the dark energy problem,while guaranteeing a positive brane tension.     

用Riccati方程构造非线性差分微分方程新的精确解

把Riccati方程应用到非线性差分微分方程求解领域,并相结合与一种函数变换,借助符号计算系统Mathematica构造了修正的Volterra方程和一般格子方程新的精确孤立波解和三角函数解. 关键词： Riccati方程 函数变换 非线性差分微分方程 孤立波解