Non-linear 2-DOF model and centre manifold theory to study limit cycle oscillations caused by drum-brake judder

This paper presents the research on the laws of systematic-parameter dependent variation in the vibration amplitude of drum-brake limit cycle oscillations (LCO). We established a two-degree non-linear dynamic model to describe the low-frequency vibration of the drum brake, applied the centre manifold theory to simplify the system, and obtained the LCO amplitude by calculating the normal form of the simplified system at the Hopf bifurcation point. It is indicated that when the friction coefficient is smaller than the friction coefficient at the bifurcation point, the amplitude decreases; whereas with a friction coefficient larger than the friction coefficient of bifurcation point, LCO occurs. The results suggest that it is applicable to suppress the LCO amplitude by changing systematic parameters, and thus improve the safety and ride comfort when applying brake. These findings can be applied to guiding the design of drum brakes.     

女大学生体育运动态度的调查研究

从态度的三个层面：认知层面、情感层面、行为层面对师专女大学生体育运动的态度进行研究分析．结果表明，就整体而言师专女大学生对体育运动的认识处于较低水平．她们特别重视自身参加锻炼的情感体验，对体育运动的行为倾向处于一般水平，     

福州市部分高校硕士研究生体育行为之探微

本文通过对福州市4所高校130多名在读硕士研究生的体育行为进行调查，分析得出大部分高校研究生有积极的体育行为，主要以强身健体，放松自我为目的，影响高校研完生体育行为的因素主要有时间、场地、器材以及体育意识等，针对以上原因，文章进一步提出促进研究生参加体育活动的方法。     

Modeling of Normal Perforation of Reinforced Concrete Slabs by a Rigid Projectile

An analytical model on the normal perforation of reinforced concrete slabs is constructed. The effect of reinforcing bars is further hybridized in a general three-stage model consisting of initial cratering, tunnelling and shear plugging. Besides three dimensionless numbers, i. e. , the impact function /, the geometry function of projectile N and the dimensionless thickness of concrete target X, which are employed to predict the ballistic performance of perforation of concrete slabs, the reinforcement ratioρs of concrete and the tensile strength fs of reinforcing bars are considered as the other main factors influencing the perforation process. Simpler solutions of ballistic performances of normal perforation of reinforced concrete slabs are formulated. Theoretical predictions agree well with individual published experimental data.     

体育教育专业学生学习心态的调查研究

为迎合21 世纪高规格体育师资培养的需要, 我国高等院校体育教育专业加快了实施整体性改革的步划。本文从体育教育专业学生的专业课程选择趋向, 理论课程的认识倾向、教师教学行为及教学环境的影响这一角度,分析与阐述他们的学习心态。从而为教育部门了解与掌握体育教育专业大学生学习心态提供重要的理论信息, 为体育教育专业教学改革提供了一定的参考依据.     

一类部分和乘积的重对数律

对独立同分布的正的均方可积的随机序列,证明了一类部分和乘积在适合的正则化因子下的某种重对数律,进一步丰富了概率极限理论     

论知识经济与当代大学生创新行为

作者根据知识经济的要求 ,认为进行教育、教学改革以培养当代大学生创新行为的任务极为重要和迫切 ,并从宏观和微观两个方面论述了培养当代大学生创新意识、塑造创新性格、实现创新行为的可行而有效措施。     

存在主义哲学中的“时间”

存在主义是在二十世纪的二十年代初显端倪的哲学流派。它认定本真的“个体”为其哲学的衍生根柢 ,在时间的三维 (过去、现在、将来 )整体性向度上 ,对“个体”的“可能性”情状予以重视 ,彰显出死亡逼近时的个体对于自身多舛的罹难体验 ,并以此说明了“存在”的意义。本文就“个体”的存在与有限 ,剖析了这一卓尔不群的人生哲学中的时间整一性问题     

Hilbert‘s Sixteenth Problem and Its Generalization

This paper deals with Hilbert‘s 16th problem and its generalizations.The configurations of all closed branches of an algebraic curve of degreee n are discussed.The maximum number of sheets for an algebraic equation of degree n and the maximum number of limit cycles for a planar algebraic autonomous system are achieved.The author also considers different generalizations and some related problems.     

Validation of the elementary social behaviour assessment: teacher ratings of students’ social skills adapted to Norwegian,grades 1–6

This study investigated the psychometric properties of the Elementary Social Behaviour Assessment (ESBA), a teacher-report measure of students’ social skills and academic engagement adapted for use in Norwegian schools. At two times, 8 weeks apart, 151 teachers rated 793 students in Grades 1–6 on the ESBA and the Social Skills Rating System Teacher’s form (SSRS-T). Exploratory factor analysis with the first assessment suggested one or possibly two factors. Confirmatory factor analysis with the second assessment confirmed the one- or two-factor models but did not offer strong evidence for one over the other. The ESBA demonstrated good to excellent reliability. Strong concurrent and predictive correlations with the SSRS-T established criterion validity. The school and teacher levels explained only a limited amount of the total variance in ESBA scores, suggesting that teachers rate students quite similarly. The Norwegian-adapted ESBA paralleled the reliability and validity evidence from US samples.