中国县域地面坡谱分级及其与人口分布的关系

针对平均坡度指标难以稳健描述地面坡谱特征的问题,提出一种基于频率累加分位归并的坡谱分级方法。作为验证,运用数字高程模型数据将全国县域分为5个坡级,借助2000年和2020年人口普查数据分析了坡级与人口分布的关系。结果发现：（1）所提出的分级方法包含频率累加曲线的构建、基于分位数的参考曲线生成、基于相似度的类型归并3个关键步骤,由此得到的全国县域坡级划分方案具备稳健坡度梯度性、宏观空间连片性以及清晰地学含义。（2）全国县域人口数量总体保持随坡级升高而波动式缩小的特征,且二者间呈现明显的线性负相关关系,线性拟合R2从2000年的0.761上升到了2020年的0.845,20年间人口总数变化量与坡级的线性拟合R2达0.963;人口密度的极端值对其自身的坡级分布有较大影响,当剔除人口密度小于20人/km2和大于2000人/km2的区域后,两个分析年份全国县域人口密度均稳健保持着随坡级升高而线性减小（R2> 0.985）。本文为稳健表达如坡度等环境梯度提供了一种新的可行分级方法,并深化了对中国县域人口分布与坡度关系的认识。     

Intermittent control strategy for synchronization of fractional-order neural networks via piecewise Lyapunov function method

In this paper, the synchronization problem of fractional-order neural networks (FNNs) with chaotic dynamics is investigated via the intermittent control strategy. Two types of intermittent control methods, the aperiodic one and the periodic one, are applied to achieve the synchronization of the considered systems. Based on the dynamic characteristics of the intermittent control systems, the piecewise Lyapunov function method is employed to derive the synchronization criteria with less conservatism. The results under the aperiodically intermittent control show more generality than the ones via the periodically intermittent control. For each of the aperiodic and periodic cases, a simple controller design process is presented to show how to design the corresponding intermittent controller. Finally, two numerical examples are provided to demonstrate the effectiveness of the obtained theoretical results.     

Linear output-feedback-based semi-global stabilization for switched nonlinear time-delay systems

This paper focuses on the problem of semi-global output-feedback stabilization for a class of switched nonlinear time-delay systems in strict-feedback form. A switched state observer is first constructed, then switched linear output-feedback controllers for individual subsystems are designed. By skillfully constructing multiple Lyapunov–Krasovskii functionals and successfully solving several troublesome obstacles, such as time-varying delay and switching signals and nonlinearity in the design procedure, the switched linear output-feedback controllers designed can render the resulting closed-loop switched system semi-globally stabilizable under a class of switching signals with average dwell time. Furthermore, under some milder conditions on nonlinearities, the semi-global output-feedback stabilization problem for switched nonlinear time-delay systems is also studied. Simulation studies on two examples, which include a continuous stirred tank reactor, are carried out to demonstrate the effectiveness of the proposed approach.     

Understanding the topic evolution of scientific literatures like an evolving city: Using Google Word2Vec model and spatial autocorrelation analysis

Topic evolution has been described by many approaches from a macro level to a detail level, by extracting topic dynamics from text in literature and other media types. However, why the evolution happens is less studied. In this paper, we focus on whether and how the keyword semantics can invoke or affect the topic evolution. We assume that the semantic relatedness among the keywords can affect topic popularity during literature surveying and citing process, thus invoking evolution. However, the assumption is needed to be confirmed in an approach that fully considers the semantic interactions among topics. Traditional topic evolution analyses in scientometric domains cannot provide such support because of using limited semantic meanings. To address this problem, we apply the Google Word2Vec, a deep learning language model, to enhance the keywords with more complete semantic information. We further develop the semantic space as an urban geographic space. We analyze the topic evolution geographically using the measures of spatial autocorrelation, as if keywords are the changing lands in an evolving city. The keyword citations (keyword citation counts one when the paper containing this keyword obtains a citation) are used as an indicator of keyword popularity. Using the bibliographical datasets of the geographical natural hazard field, experimental results demonstrate that in some local areas, the popularity of keywords is affecting that of the surrounding keywords. However, there are no significant impacts on the evolution of all keywords. The spatial autocorrelation analysis identifies the interaction patterns (including High-High leading, High-Low suppressing) among the keywords in local areas. This approach can be regarded as an analyzing framework borrowed from geospatial modeling. Moreover, the prediction results in local areas are demonstrated to be more accurate if considering the spatial autocorrelations.     

大学英语教学中形成性评价的运用

大学英语作为高等院校的公共必修课,是培养高素质应用型人才必需掌握的一门知识。解决高等院校学生消极的英语学习状况,激发英语学习兴趣和主动性,除了改革传统的英语教学模式之外,还要改变单一的终结性评价方式,实施与教学模式相适应的形成性评价方式。关注学习者学习过程的形成性评价能够激发学习者英语学习的主动性,符合学生的个体差异性,有利于提高英语学习的效率。高等院校普遍存在的英语学习状况为形成性评价的实施提供了可能性。     

《孟子》中连用的句尾语气词

《孟子》中句尾语气词连用的情况在先秦文献中是很突出的,本文将其中句尾语气词的连用进行了穷尽性统计,并通过分析、对比得出了几点认识。     

概率论教学体验

针对概率论教学中出现的问题提出几点体验：深刻理解基本概念;在解题的过程中,力求从多方面考虑问题,作到一题多法;灵活运用基本性质。     

柏拉图教育思想对当今教改的启示

柏拉图作为西方大学雏形柏拉图学园的创立者,其教育思想至今仍然对中国教育及教学改革有着重要的借鉴价值。在教育理念方面,柏拉图致力于引导人而不是培养人才,即唤醒以理性原则行事的人,而不是如机械部件般有用于产业发展和社会需要的人才。在教学过程方面,柏拉图通过研讨的方式推进各门课程的教学,将人导向理性。这有利于刺激学生的思维,有效推进教育理念的实现,而不是仅仅灌输知识。基于以上,在教学成果方面,柏拉图获得的是超功利的音乐家、智慧的哲学王这一硕果,而不是有用的材料或长脚的书柜。     

浅议谢灵运山水诗的创作特色

历代文学评论家对谢灵运的思想和世界观褒贬不一,但就他对山水诗创作的贡献而言却是公认的。本文就谢灵运山水诗的创作风格、艺术手法进行比较全面的阐述,并与陶渊明诗歌特点作以比较,从而更加突出表现谢灵运对我国山水诗创作的杰出贡献。     

湖北省农产品加工企业一线员工薪酬制度设计

科学设计一线员工薪酬制度,对稳定一线员工队伍、提高其素质和技能,具有激励和促进作用。文章结合湖北省农产品加工企业一线员工薪酬结构及特点,分析了其薪酬制度存在的问题;提出了其薪酬制度设计的要求;探索了完善农产品加工企业一线员工薪酬制度的措施：完善薪酬决策和考评机制;完善激励薪酬制度;合理运用非物质激励和负激励手段。