Goal Change in the Situation Calculus

Although there has been much discussion of belief change (e.g.[4, 21]), goal change has not received much attention. In thispaper, we propose a method for goal change in the frameworkof Reiter's; [12] theory of action in the situation calculus[8, 10], and investigate its properties. We extend the frameworkdeveloped by Shapiro et al. [17] and Shapiro and Lespérance[16], where goals and goal expansion were modelled, but goalcontraction was not.     

Editorial

Abstract

Defining and measuring sustainability is a major challenge. This article argues these limitations need not stop us from trying to identify and value the possible impacts of what we are doing, or are thinking about doing, over time periods much longer than the lives of our investments, or even of the lives of those of us living today. Sustainability is a relative concept that must be applied in an environment undergoing multiple changes, changes that are occurring over different temporal and spatial scales. We depend on our water resource systems for our survival and welfare. Yet no one expects them to be restored to, or survive in, their most productive pristine states in the face of increasing development pressures for land in their watersheds and for water in their streams, rivers, lakes, and aquifers. A continuing task of water resource planners and managers is to identify the multiple impacts and tradeoffs resulting from what we who are living today may wish to do for ourselves and our immediate children and what we can only guess our yet-to-be-born descendants may wish us to do, or not do, for them in some distant future. This task must involve professionals from other disciplines in a context much broader than just water management. Once these impacts and tradeoffs are identified, it is then up to the political process to make choices when they are in conflict. All of us need to be a part of this decision-making process.     

经典传说的新语境分析:以牛郎织女传说为例

牛郎织女传说作为我国四大传说之一,在历史传承中发生了文化变迁,其影响日益式微。在当代语境下,后现代主义思潮的推动,新科技手段的应用,为牛郎织女传说的传承提供了新的机遇。本文拟就对牛郎织女历史语境及当代语境作出分析,同时对牛郎织女未来保护与传承进行构想与展望,思考牛郎织女传说的发展辙迹。     

受控振动柱体对波浪影响的数值模拟研究

以不可压缩黏性流体的Navier-Stokes方程为控制方程,采用RNG k-ε湍流模型,利用VOF方法追踪运动的自由表面的方法,建立了三维数值波浪与振动柱体相互作用的模型.基于经典绕射理论验证了波浪绕固定柱体传播的数值模型的可靠性,再采用动边界技术赋予柱体振动规律,研究受控振动柱体对波浪传播的影响,并通过控制柱体初始振动相位变化,系统地给出了在柱体振动的不同初始相位下柱体前后波浪变化的规律.     

中原经济区建设与河南高职教育发展方式研究

面对中原经济区建设的现状,河南高职教育也应紧跟时代步伐,切实转变发展方式,坚持重质量、重内涵,增强政府的主导作用、优化专业结构、创新办学模式,实现高职教育的健康、协调、持续发展,从而为中原经济区建设提供强有力的人才支撑。     

Dynamics of polymer electrolyte fuel cells undergoing load changes

Numerical simulations are carried out for a single-channel polymer electrolyte fuel cell (PEFC) undergoing a step increase in current density. The objective is to elucidate profound interactions between the cell voltage response and water transport dynamics occurring in a low-humidity PEFC where the membrane hydration and hence resistance hinges upon the product water. Detailed results are presented to show that a step increase in the current density leads to anode dryout due to electroosmotic drag, while it takes several seconds for water back-diffusion and anode humidified gas to re-wet the anode side of the polymer membrane. The water redistribution process is controlled by water production, membrane hydration, electroosmotic drag, and water diffusion in the membrane. The anode dryout results in a substantial drop in cell voltage and hence temporary power loss. Under extreme situations such as dry anode feed, large step increase in the current density, and/or lower temperatures, the cell voltage may even reverse, resulting in not only power loss but also cell degradation. Finally, the dynamics of current distribution after a step change in gas humidification is numerically examined.     

点到平面距离公式的一种新证法

该文根据球面上一点切平面的方程和平移变换,对空间任一点P(x0,y0,z0),分P点为坐标原点和P点不是坐标原点两种情形,给出了到平面π:Ax By Cz D=0的距离公式d=|Ax0 By0 Cz0 D|/√A2 B2 C2 的一种新证法.     

关于学习和动机关系的研究(英文)

讨论了心理学中学习和动机的关系,从八个方面详细介绍了学习过程中动机的作用,研究了不同情况下不同的动机对学习产生不同的影响,最后讨论了不同起源的学习动机的改变法则。     

习俗·象征与地位:静升住宅装饰的文化内涵

传统村落中的住宅装饰不仅在于美观,还象征着不同人群的社会地位。趋吉避凶的心理更使村民对特定构件进行重点修饰,从而显示出他们的习俗。在不同的历史时期,住宅装饰的变化往往体现出崭新的价值观和对“现代化”生活的向往。本文通过研究和比较静升村内的各类装饰题材和装饰手段,分析了文化变迁对住宅装饰的影响。