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HUXiaohong ZHANGXingyou 《重庆大学学报(英文版)》2004,3(1):89-91
The existences of the global attractor A^ε for a degenerate parabolic equation and of the homogenized attractor A^0 forthe corresponding homogenized equation are studied, and explicit estimates for the distance between A^ε and A^0 are given. 相似文献
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Kenneth A. Feldman 《Research in higher education》1984,21(1):45-116
A systematic analysis of extant studies reveals, on average, a very weak inverse association between the size of class enrollment in a college course and students' overall evaluation of the course and its teacher, as well as between class size and evaluations of specific instructional dimensions pertaining to the instructor's skill in presenting material and communicating information. Larger inverse associations are typically found between class size and evaluations of specific instructional dimensions pertaining to the instructor's interactions and interrelationships with students. This pattern of findings is consistent with the accumulating evidence that the instructional dimensions of the first set have greater importance for students in forming their global opinions of teachers and courses than do those of the second set. The further finding in some studies of a negative curvilinear (roughly U-shaped) relationship between class size and evaluations is noted and discussed. Implications for the validity of teacher evaluations are considered and the related question of whether class size biases these evaluations is explored. 相似文献
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Different two-equation k-ε models were used to simulate the gas flow field generated by a new type of circulating fluidized bed reactor with venturi gas distributor. The numerical results were compared with the experimental data. It has been shown that the simulation results from the standard k-ε model have the best match with the experimental data. Based on this model, the gas flow field in the venturi diffuser and riser was analyzed by the concept of velocity nonuniformity and dead zone percentage. Both the nonuniformity of gas velocity and the dead zone percentage reach the maximum at the venturi outlet due to the effect of the vortex. At the same time, it provides a good platform for the further optimization of the inlet configuration of circulating fluidized bed reactor. 相似文献
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极限ε—语言在高等数学学习中有重要的地位。但是,在极限ε—语言学习过程中存在诸多的学习障碍,影响ε—语言认知结构的形成。通过分析ε—语言学习的认知过程,探讨ε—语言图式的形成和精深。 相似文献
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垄断是经济发展的结果,其存在有一定的经济和法理基础,具有积极效应的一面。规定反垄断适用除外制度是各国立法的必然,也是一种先进的立法技术。我国反垄断法适用除外制度的豁免对象应当结合我国国情、国际上的先进立法和世贸规则进行确立、实行和完善。 相似文献
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Quadratic 0-1 problems with linear inequality constraints are briefly considered in this paper.Global optimality conditions for these problems,including a necessary condition and some sufficient conditions,are presented.The necessary condition is expressed without dual variables.The relations between the global optimal solutions of nonconvex quadratic 0-1 problems and the associated relaxed convex problems are also studied. 相似文献
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Quadratic 0-1 problems with linear inequality constraints are briefly considered in this paper.Global optimality conditions for these problems,including a necessary condition and some sufficient conditions,are presented.The necessary condition is expressed without dual variables.The relations between the global optimal solutions of nonconvex quadratic 0-1 problems and the associated relaxed convex problems are also studied. 相似文献
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研究一类具有不连续治疗策略和非线性发生项的SIR模型.首先运用右端不连续的微分方程理论定义模型的Filippov解,然后证明该模型的全局行为由阈值R0确定,即当R0≤1时,无病平衡点全局渐近稳定. 相似文献
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研究一类有理差分方程xn+1=a-bxn/A-Bxn-1(n=0,1,2,…,a,b,A,B0)的全局行为.应用不动点原理、数学归纳法、构造辅助函数法和反证法,得到了这一类有理差分方程的稳定性、持久性、全局吸引性和素二正周期解. 相似文献
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讨论了一类具有非线性传染率的SEIS流行病模型,当基本再生数R0<1时,无病平衡点全局渐近稳定;基本再生数R0>1时,地方平衡点全局渐近稳定. 相似文献
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A significant global trend during the 1990s is the restructuring of higher education systems. The essence of this restructuring process is a redefinition of the relationship between institutions of higher learning, the state, and the market, and a drastic reduction of institutional autonomy. This article is an analysis of the restructuring process in the forms of privatisation of higher education and corporatisation of public universities in Malaysia. This analysis highlights the context of higher education reforms in the era of globalization, major trends in higher education reforms and Malaysias responses to these global trends. By focusing on the institutional level, this article examines the expansion and diversification of private higher education as well as the change in the governance and culture of public universities brought about by privatisation and corporatisation. 相似文献
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利用1995年、2004年LandsetTM遥感影像提取研究区土地利用数据,通过DEM模型并提取坡度、高程因子,利用ArcGIS的叠加分析功能,获取研究区近十年来土地利用随高程和坡度的变化状况．研究结果表明：近十年来临沂市北部山区土地利用／覆被变化随坡度和高程的变化具有明显的规律,土地利用变化随着高程的增加、坡度的增大而减缓;土地利用变化主要集中在0-400m高程且坡度小于25°范围的坡地,其中以耕地和林地的转化最为剧烈． 相似文献
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Preliminary construct and concurrent validity of the Preschool Self-regulation Assessment (PSRA) for field-based research 总被引：2，自引：0，他引：2
Radiah Smith-Donald C. Cybele Raver Tiffany HayesBreeze Richardson 《Early childhood research quarterly》2007
This study introduces a portable direct assessment of young children's self-regulation—the Preschool Self-Regulation Assessment (PSRA). The PSRA was designed to assess self-regulation in emotional, attentional, and behavioral domains by using a brief, structured battery of tasks in conjunction with a global report of children's behavior. Factor analyses from a pilot sample (N = 63) of Head Start children revealed two self-regulation factors reflecting children's performance on tasks of impulse control and tasks of compliance/executive control. Assessor report of children's behavior during the assessment was reduced into two additional factors reflecting children's global attention/impulse control and positive emotion. Moderate correlations between self-regulation factors and children's social competence, behavior problems, and early academic skills, provide preliminary evidence of the new measure's validity, and additional empirical evidence for bivariate relations between academic and self-regulatory competence. 相似文献
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通过采用Possion方程进行正交离散网格的生成技术对总扩散角为8°、扩散度为4的锥形渐扩管内充分发展的不可压粘性紊流场生成正交离散网格,并绘制出了在此方法下的网格生成图。 相似文献
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深入研究了一种融合Web服务、网格和对等计算技术,提出了基于管理域划分的空间信息资源管理系统模型,讨论了空间信息资源的部署与发现和空间信息资源的静态调度和动态调度,通过资源级调度和用户级调度二级调度,支持资源提供者和使用者双方协商服务级协定的实现,详细介绍了异构环境中任务迁移的动态关键路径的静态调度算法.在空间信息资源管理模型的基础上,讨论了单一入口点、单点控制、全局用户管理、全局资源管理和全局任务管理构件的相关实现技术. 相似文献
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This study examined the concurrent validity of the Peabody Picture Vocabulary Test-Revised (PPVT-R) and the Kaufman Assessment Battery for Children (K-ABC) with 47 students referred for learning difficulties. A comparison of the correlations of each of the criterion measures from the K-ABC global scales showed a more substantial relationship between the PPVT-R standard score and the K-ABC Achievement scale than with other K-ABC scales. In an effort to further examine the relationship between the PPVT-R and the K-ABC, a stepwise multiple regression was calculated, with the standard scores of the K-ABC global scales serving as the predictor variables of the PPVT-R. This analysis indicated that the K-ABC Achievement global scale was the only significant predictor of the PPVT-R. Implications for practitioners were discussed. 相似文献
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研究了具无界时滞多滞量的非自治Logistic方程X′(t) +∑mi=1ai(t)〔1+x(t)〕x(t-τi(t) =0的零解的全局渐近稳定性 ,获得了方程的零解为全局渐近稳定的充分条件 ,所得结果推广并改进了许多熟知的结论 相似文献
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Access to global information fundamentally alters the information scanning function of decision-makers. The flattening of the management pyramid means information scanning of external sources is being performed by personnel in middle and lower levels of management, not only in the traditional senior management level. Both graduate and undergraduate classes in information systems can effectively address the use of external information scanning through the teaching of Internet skills. This paper presents the course outline for a class in Global Communication Networks where a project-oriented approach was used to teach web-based skills. The importance of global information systems in decision-making and the use of the Internet as an information resource were emphasized in this class. A survey of students in the class found that this approach was successful in improving the perceived value of Internet-related tools for information scanning and professional decision-making. 相似文献