含有DM相互作用的混合XXZ模型的临界性质

利用平均场近似的方法,研究了立方晶格上具有DM相互作用的混合XXZ模型的相变和临界性质.在Ising极限下,在不同的DM相互作用参量D下做出了系统的自发磁化强度m随约化温度T=1/K的变化,得到了系统的临界温度,分析了DM相互作用对系统临界温度的影响;在不同的各向异性参数△下作出了系统二级相变线,结果表明混合自旋XXZ系统只存在二级相变,系统没有出现三临界点.     

Student Engagement and School Burnout in Finnish Lower-Secondary Schools: Latent Profile Analysis

Self-ratings of behavioural engagement, cognitive engagement and school burnout were used in person-centred analyses to identify latent profiles among 2,485 Finnish lower-secondary school students. Three profiles were identified: high-engagement/low-burnout (40.6% of the sample), average-engagement/average-burnout (53.9%), and low-engagement/high-burnout (5.5%). Another sample of lower-secondary school students was used to validate the 3 profiles. The factors most strongly associated with the high-engagement/low-burnout profile of lower-secondary school students’ were high levels of support from teachers and family, good academic performance, and lack of truancy. The study indicated that teacher and family support and students’ academic achievement are pivotal in understanding student engagement and school burnout.     

A quadratic programming method for optimal degree reduction of Bézier curves with G1-conitnuity

This paper presents a quadratic programming method for optimal multi-degree reduction of Bézier curves with G1-continuity. The L2 and l2 measures of distances between the two curves are used as the objective functions. The two additional parameters, available from the coincidence of the oriented tangents, are constrained to be positive so as to satisfy the solvability condition. Finally, degree reduction is changed to solve a quadratic problem of two parameters with linear constraints. Applica     

一类一致混合超图的上、下色数

本文研究了在l、m固定的情况下,删除完全一致混合超图κ（n,l,m）的若干C-超边和D-超边后其上、下色数的变化.     

一致凸Banach空间非扩张映象带双误差的Ishikawa迭代

在一致凸Banach空间上，研究了半紧的非扩张映象‖Tx-Ty‖≤‖x—y‖的Ishikaww序列的收敛问题，建立并证明了带双误差的Ishikawal迭代逼近收敛定理，从而推广并改进了某些已知的结果．     

非线性三阶边值问题正解的存在性

利用上、下解方法,研究三阶微分方程解与正解的存在性.然后给出了所获结果的一个应用.     

奇性二阶微分方程边值问题的微分不等式

研究奇异性二阶微分方程的边值问题 ,通过构造上下解 ,并利用Nagumo的思想和截断函数的技巧 ,得到了解的存在性及微分不等式 .     

由农村税费改革引发的思考

农村税费改革在切实减轻农民负担,维护农村稳定方面取得了很大成果,但仍存在一些问题,应及时调整改革思路,不断完善改革方案,深入推进农村税费改革,建立一个符合市场经济要求,促进农村经济和农业生产建康、持续发展的城乡统一的现代化农业税收制度。     

素数阶循环图与Ramsey数下界

简述Ramsey数下界研究的历史背景和主要困难，简介我们的理论和方法。