音乐教师如何面对新世纪的教育

音乐教育对于培养和提高人的综合素质有着独特的功能和作用。基础教育课程改革的全面推进,体现了素质教育的基本精神,也为音乐教育的发展提供了难得的机遇和广阔的空间。展望新世纪的发展,音乐教育会呈现一些显著的变化和特征。     

气体绝热自由膨胀过程中温度的变化

气体在绝热的密闭容器中自由膨胀，体积不断增大，从而导致体系的温度、内能、焓等状态函数相应发生改变，对于不同的气体，这些变化也相应不同。论分别对理想气体、范氏气体、满足方程P（Vm-b）＝RT的实际气体、任意实际气体等几种不同性质的气体进行讨论。     

可变换为二阶常系数线性微分方程的判别准则

本文给出了二阶性微分方程能够利用变换化为二阶常系数线性微分方程的充要条件。     

甘肃省2000—2020年土地利用变化分析及基于PLUS的生态空间多情景模拟

在甘肃省经济快速发展的背景下,通过分析甘肃省土地利用时空演变特征与预测“三生”空间变化趋势,能为甘肃省推动区域高质量发展提供决策辅助。本文先分析20年间甘肃省土地利用变化特征并挖掘诱因,再模拟甘肃省的“三生空间”在四种情景下的变化趋势。由结果可知：在2000~2020年期间,甘肃省草地和耕地的面积持续缩小,主要集中在酒泉市、张掖市;建设用地面积持续扩大,定西、甘南、临夏交界处的水域、林地面积小幅增加;未利用土地面积增加;草地与建设用地转换程度最剧烈。由多情景模拟结果可知：除了强调发展生产情景外,生产空间均呈萎缩趋势;林地、水域持续扩张,草地大面积缩小,导致生态空间在各情景模拟中呈缩小趋势;生活空间则均呈扩张趋势。“三生空间”在发展综合优化情景中的预测变化趋势与生活条件提高情景的模拟结果相似,但前者更平缓。甘肃省应该抓住发展机遇,推动产业转型并促进土地高效利用,重视酒泉生态恶化问题并及时提出应对措施,积极改善北山山地区荒漠环境,走上可持续发展道路。     

The Study of the Change of Fine-structures in Rotational Energy Transfer of NH2 ()

By using the high resolution dispersion spectra of NH2(~A2A1,090) 423(F1/F2) it is ob-served that the spin-rotational conservation transition is dominant for the parent levels. It con-firms the assumption that the electron is a spectator at single collision between open-shell and close-shell molecules. As to the daughter levels, the tendency for the conservation of the spin-rotation coupling of the parent level is found and may be explained by the long range interaction between those molecules.     

Monotone Comparative Statics: Geometric Approach

We consider the comparative statics of solutions to parameterized optimization problems. A geometric method is developed for finding a vector field that, at each point in the parameter space, indicates a direction in which monotone comparative statics obtains. Given such a vector field, we provide sufficient conditions under which the problem can be reparameterized on the parameter space (or a subset thereof) in a way that guarantees monotone comparative statics. A key feature of our method is that it does not require the feasible set to be a lattice and works in the absence of the standard quasi-supermodularity and single-crossing assumptions on the objective function. We illustrate our approach with a variety of applications. We are grateful to Kenneth Arrow, Darrell Duffie, David Luenberger, Paul Milgrom, John Quah, and Pete Veinott for helpful comments. Research in part supported by a David Morgenthaler II Faculty Scholar Award.     

调压降耗的极值求解

本文提出了一种在电力网络中基于不变损耗与可变损耗之比例关系通过调压来降低网损的方法。推导出了该比例 C 与电压调整极值点 P_m 的关系为 P_m=[(1-C)/C]~(1/4).据此计算出了电压调整的极限与网损变动的极限。对现实有指导意义。     

A General Class of Change Point and Change Curve Modeling for Life Time Data

Change point hazard rate models arise in many life time data analysis, for example, in studying times until the undesirable side effects occur in clinical trials. In this paper we propose a general class of change point hazard model for survival data. This class includes and extends different types of change point models for survival data, e.g. cure rate model and lag model. Most classical approach develops estimates of model parameters, with particular interest in change point parameter and often the whole hazard function, but exclusively in terms of asymptotic properties. We propose a Bayesian approach, avoiding asymptotics and provide inference conditional upon the observed data. The proposed Bayesian models are fitted using Markov chain Monte Carlo method. We illustrate our proposed methodology with an application to modeling life times of the printed circuit board.     

机床变速齿轮当量载荷的计算

为计算机床变速齿轮的承载能力,须求出所作用的非稳定载荷的当量载荷。本文取长期作用的最大载荷为名义载荷,利用变动工作用量系数K_(Pnt)对名义载荷进行修正来计算当量载荷。文中对K_(Pnt)的计算式进行了深入的研究,并给出了发K_(Pnt)的极限值。