具p-Laplacian算子二阶多点边值问题正解的存在性

通过利用锥上,不动点定理研究一类具p-Laplacian算子二阶微分方程多点边值问题正解的存在性,得到了正解的存在性定理。     

教育评估的边界理性

评估有大用,但在整体的教育质量保障体系当中,作为客体和手段存在的评估行为却需要理性地把握好大有作为的边界。本文从灵动的教育、有限的指标以及变化的评估者三个层面上辨析了教育评估“有为”与“无为”之间的模糊界面,认定理智适度的作为方式才是教育评估可持续发展的真正保障。     

Policy as Boundary Object: A New Way to Look at Educational Policy Design and Implementation

Policy implementation research in general and educational policy in particular is loosely connected to policy-making processes. There is a gap particularly in the field of vocational education. This often leads to conflicts and contradictions between policy-maker objectives and end-user implementation. To avoid such a disconnect, the relation between the world of end users and the world of decision-makers should be carefully constructed. This might be done through connecting the process of decision-making to implementation and carefully developing methods that encompass the demands of decision-makers and the needs and informational requirements of end users. Our intensive case study research on the process of a vocational education reform in the marine sector confirms that the lack of robust connection and active engagement of implementers as the end-users in the design of the policy created challenges for its implementation. Using a theoretical framework based on the notion of boundary objects we bring an alternative to current practice by creating the potential to illuminate and remove tensions and challenges for policy implementation. From there we infer that adopting this concept for policy design may prevent such conflicts and contradictions and result in successful implementation.

Optimal boundary control of heat conduction problems on an infinite time domain by control parameterization

The present paper deals with an optimal boundary control problem in which the process of systems under consideration is governed by a linear parabolic partial differential equation over an infinite time interval. The objective of the paper is to determine the optimal boundary control that minimize a given energy-based performance measure. The performance measure is specified as a quadratic functional of displacement and a suitable penalty term involving the boundary controls. In order to determine the optimal boundary controls, the problem with boundary controls are converted into a problem with distributed controls. The modal space technique is then used to reduce the system into the optimal control of time invariant lumped parameter system. The associated system of uncoupled first order initial value problems is solved in terms of controllers. Next step deals with the computation of the control and trajectory of the linear time-invariant lumped parameter. For this we approximate the controllers by a finite number of orthogonal exponential zero-interpolants over the interval [0,∞). The resultant performance index after using the optimality condition leads to a system of linear algebraic equations. The suggested technique is easy to implement on digital computer. We provide a numerical example to demonstrate the applicability and efficiency of the proposed approach.     

北海油气资源与周边国家边界划分

人类的物质需求归根到底是一种能量需求。工业革命使人类从利用有机能源跃进到利用无机能源。西欧依靠使用千百年累积起来的能源走出了17世纪危机的困境,北海油气资源的开发成为20世纪西欧复兴的一种自然因素。北海沿岸国家社会经济对北海资源具有很大的依赖性,北海油气资源的占有和使用变成一个人们不得不关注的现实问题。北海丰富的资源和周边国家之间的协议为北海资源开发创造了条件。     

无铅压电陶瓷钛酸铋钠驰豫铁电性

金属氧化物沉积法(MOD)成功地制备了Bi1/2Na1/2TiO3(NBT)基无铅压电陶瓷,样品的X射线衍射(XRD)结果显示其具有较好的结晶性,通过介电温度谱和介电弥散性指数δ、介电临界指数γ和频率色散度△Tm对样品的驰豫性质进行了定量研究,结果表明,NBT是一种A位取代的驰豫铁电体,它具有钙钛矿结构,以及极其复杂的相变过程,在一定的温度范围内可以得到三方和四方共存的准同型相界区。     

基于广义Adams边值法的循环预条件解微分方程

Chan和Bertaccini等提出使用循环矩阵作为预条件矩阵的GMRES方法来求解由边值法(BVM)离散常微分方程初值问题的线性系统是优于GMRES方法的.本文基于广义Admas法(GAMs)离散常微分方程初值问题的线性系统中矩阵的双对角形式,提出了一类新的循环预条件矩阵来加速GMRES的收敛性,并且从理论上证明了方法的收敛性,数值实验表明了这种方法的有效性.     

整数规划边界平移收缩阶梯解法研究

在整数规划传统解法──匈牙利法、分枝定界法、割平面法的同时,提供一种新的边界平移收缩──阶梯求解法．它与传统的解法相比较,计算量小,且能较快求得最优整数解．     

基于拟合函数的艾滋病治疗模型的评价

艾滋病的治疗方法很多,为了能够准确、及时、有效地治疗艾滋病,需要从众多的治疗方案中找到合适的一种,为此利用拟合函数、边际疗效和性价比建立了一个评价艾滋病疗法优劣的数学模型.并利用计算机中的数据库知识对该数学模型进行了分析,使它更接近现实生活中艾滋病的治疗.