南京栖霞山风景区色叶树种资源的利用与保护

调查表明 ,南京栖霞山风景区现有色叶树种 2 0余种。分析了色叶树种性状退化的主要原因有水分亏缺、空气污染、病虫危害和旅游干扰等 4个方面 ,并提出了包括采取科学的林分改造技术措施及加强对抗逆性强的色叶树种和非色叶树种选育研究在内的 8项资源合理利用与保护对策     

图解在英语语法教学中的应用

例证说明，图解法在英语教学中有奇妙的作用．英语教学中应用图解法、括号图解和树形图解讲解简单句、复合句、助动词和名词等可以使学生对英语语法结构及其规律有一个直觉认识。     

Finding a Length-Constrained Maximum-Density Path in a Tree

Let T = (V,E,w) be an undirected and weighted tree with node set V and edge set E, where w(e) is an edge weight function for e E. The density of a path, say e₁, e₂,..., e_k, is defined as ^k_{i = 1} w(e_i)/k. The length of a path is the number of its edges. Given a tree with n edges and a lower bound L where 1 L n, this paper presents two efficient algorithms for finding a maximum-density path of length at least L in O(nL) time. One of them is further modified to solve some special cases such as full m-ary trees in O(n) time.     

金融网络风险下多因子矩阵回归的资产组合与定价

本文从企业的股权、债权关系出发,基于违约距离构建无向图网络,分析了不确定性风险以网络形式进行传染、溢出和蔓延等现象,通过最小生成树的稀疏网络优化方法最大限度降低资产组合的非线性风险影响。站在资源配置的角度,利用稀疏聚类算法深入挖掘资产特征和捕捉其间的相依关系,采用多目标、多指数的稳健矩阵回归策略动态跟踪市场趋势,并通过自适应权重学习策略对网络风险叠加影响下的资产组合进行选择和配置,最终获得最小生成树风险下投资组合的稀疏聚类优化策略,进一步扩充了资产定价多因子模型。研究发现多目标矩阵回归的稀疏聚类投资组合,不仅对组合内投资标的进行了选择性舍弃,使资金能够集中配置于优质资产,更有助于通过最小生成树减缓甚至切断风险在网络中的传播,有效降低了资产之间风险的传染性。基于金融网络的风险分析方法不仅有效地刻画了风险以网络方式互相传染、互相影响、互相强化的非线性叠加效应,而且通过资产之间配置系数的压缩变换和最小生成树的优化方式,最小化最坏情形下风险传染的影响,对复杂网络环境下的资产配置和全面风险管理进行了有益补充,为长期投资基金获得风险和收益更为均衡的资产配置,提供了合意的投资策略和决策依据。     

从 WTO 到 TPP--一种科技哲学的视角分析

从科技哲学的理论来看,全球化伴随着熵增,而 WTO 则导向熵减。由功能耦合所构建的全球产业链,让世界从恐怖下的和平到相互依存的和平。金融危机瓦解了全球产业链,世界陷入分岔点,竞争、动荡和不确定成为主导,各国竞相争夺未来世界的主导权。TPP 达成一致,意味着美国在为未来的全球产业链制定规则上迈出了一大步。由 WTO 到 TPP,是 WTO 的扩展和提升,阴谋论于事无补。中国宜认清潮流,打牢基础,以开放促改革,积极准备加入 TPP,参与今后规则的制定,共同构建人类命运共同体。     

An Adaptive Simulation Framework for the Exploration of Extreme and Unexpected Events in Dynamic Engineered Systems

The end states reached by an engineered system during an accident scenario depend not only on the sequences of the events composing the scenario, but also on their timing and magnitudes. Including these additional features within an overarching framework can render the analysis infeasible in practical cases, due to the high dimension of the system state‐space and the computational effort correspondingly needed to explore the possible system evolutions in search of the interesting (and very rare) ones of failure. To tackle this hurdle, in this article we introduce a framework for efficiently probing the space of event sequences of a dynamic system by means of a guided Monte Carlo simulation. Such framework is semi‐automatic and allows embedding the analyst's prior knowledge about the system and his/her objectives of analysis. Specifically, the framework allows adaptively and intelligently allocating the simulation efforts preferably on those sequences leading to outcomes of interest for the objectives of the analysis, e.g., typically those that are more safety‐critical (and/or rare). The emerging diversification in the filling of the state‐space by the preference‐guided exploration allows also the retrieval of critical system features, which can be useful to analysts and designers for taking appropriate means of prevention and mitigation of dangerous and/or unexpected consequences. A dynamic system for gas transmission is considered as a case study to demonstrate the application of the method.     

Learning from mixed OR method practice: The NINES case study

Despite continued interest in the use of mixed OR/MS methods, limited attention has been paid in the literature to generic lessons that could be gained from mixing methods in practice. Many organisational problems demand the use of a mixed method approach and thus recognising and sharing lessons could prove beneficial to both practitioners and researchers. This paper reports on an in-depth evaluation of a case study involving risk identification and quantification of the Northern Isles New Energy Solutions (NINES) project which sought to trial and plan a new energy system. The intervention involved a mixed method approach and client feedback on the efficacy of the approach was sought. The evaluation reported in this paper is carried out using a set of themes taken from the literature and seeks to highlight transferable lessons. The set of lessons that emerge are presented along with their implications for both general OR modelling practice and the specific situation of mixing OR/MS methods. The paper concludes by discussing the implications of the work and directions for future work which will be of interest to both practitioners and researchers interested in mixed method OR/MS work.     

A Meta‐Analysis of Carbon Nanotube Pulmonary Toxicity Studies—How Physical Dimensions and Impurities Affect the Toxicity of Carbon Nanotubes

This article presents a regression‐tree‐based meta‐analysis of rodent pulmonary toxicity studies of uncoated, nonfunctionalized carbon nanotube (CNT) exposure. The resulting analysis provides quantitative estimates of the contribution of CNT attributes (impurities, physical dimensions, and aggregation) to pulmonary toxicity indicators in bronchoalveolar lavage fluid: neutrophil and macrophage count, and lactate dehydrogenase and total protein concentrations. The method employs classification and regression tree (CART) models, techniques that are relatively insensitive to data defects that impair other types of regression analysis: high dimensionality, nonlinearity, correlated variables, and significant quantities of missing values. Three types of analysis are presented: the RT, the random forest (RF), and a random‐forest‐based dose‐response model. The RT shows the best single model supported by all the data and typically contains a small number of variables. The RF shows how much variance reduction is associated with every variable in the data set. The dose‐response model is used to isolate the effects of CNT attributes from the CNT dose, showing the shift in the dose‐response caused by the attribute across the measured range of CNT doses. It was found that the CNT attributes that contribute the most to pulmonary toxicity were metallic impurities (cobalt significantly increased observed toxicity, while other impurities had mixed effects), CNT length (negatively correlated with most toxicity indicators), CNT diameter (significantly positively associated with toxicity), and aggregate size (negatively correlated with cell damage indicators and positively correlated with immune response indicators). Increasing CNT N₂‐BET‐specific surface area decreased toxicity indicators.     

中国管理学研究的人本主义范式

哲学视野审视下的中国传统管理文化以战略为管理的核心，其所蕴含的丰富的人本主义思想在管理实践中表现为科学、艺术和哲学3种元素的融合。战略之树的比喻提供了中国管理学的认识框架，可以推动管理科学研究与管理哲学研究的统一，继而促成中国传统管理文化与管理科学的内在整合。中国管理学的意义在于推动管理学研究从科学主义范式走向人本主义范式。     

论陕北汉画像圣树符号的宇宙论意义

作为汉代思想的物质载体,刻有圣树符号的陕北汉画像石造型多呈竖立型,反映了宇宙划分为天堂与人间,圣树为连接天堂与人间的唯一通道这样一种二分的垂直宇宙论。圣树图像并非为汉陕北汉画像石所独有,它普遍存在于世界各地的神话与仪式中,其原型为史前时代的宇宙树。圣树符号的史前图像探源表明,陕北汉画像石中的圣树图像并不是汉代升仙与厚葬思想的产物,其构图范式源自史前口传时代大传统以圣树为中心的神话宇宙论。