江苏省城市洪涝韧性评价及影响因素研究

基于压力-状态-响应(PSR)框架,构建城市洪涝韧性评价指标体系,并运用基于实数编码加速遗传算法的投影寻踪模型(RAGA-PP)和灰色关联度分析法对江苏省各市洪涝韧性进行总体评价及影响因素分析。结果表明:13个地级市城市洪涝韧性指数由大到小排序依次为南京、苏州、无锡、常州、南通、镇江、徐州、泰州、扬州、连云港、淮安、盐城、宿迁;江苏省城市洪涝韧性呈现明显的两极分化趋势,苏南优于苏北;防汛物资储备调拨能力、公众灾害应急意识、居民人均可支配收入、第三产业占比、人均地区生产总值、排水管网长度和高等院校毕业生数等指标对城市洪涝韧性影响较大。     

旅游地投射形象与感知形象对比研究——以秦皇岛滨海长城形象为例

良好的旅游形象可以刺激旅游动机的产生,从而引发相应的旅游决策行为。因此做好旅游目的地旅游形象定位和设计具有重要意义。以秦皇岛为例,基于网络文本数据利用内容分析法分析秦皇岛目的地滨海长城旅游形象。研究发现,官方投射形象与游客感知形象均围绕长城形象构建,但关注核心与构建路径具有差异;官方投射形象所关注的维度依次为人文吸引物、服务与管理、旅游体验、旅游设施、自然吸引物;游客通过感知建构的滨海长城旅游形象的关注维度依次为人文吸引物、旅游体验、自然吸引物、旅游设施、服务与管理。基于此,应将长城与滨海、人文与自然多维融合,立体化塑造滨海长城目的地形象,加强形象宣传力度,提升游客旅游体验感。     

积分定义及对称性

本文给出了线、面、体积分定义的一般描述,并导出了利用对称性简化积分计算的定理。     

快速校正天波雷达电离层相位污染的改进方法

时变的电离层会对天波超视距雷达(OTHR)回波信号相位进行调制,产生相位污染,导致回波谱展宽。最大似然估计(MLE)法具有比相位梯度法更佳的污染校正效果,但计算量非常大。通过引入投影近似子空间跟踪法,提出了一种改进的MLE方法。改进方法采用递归手段估计最大特征值对应的特征向量,避免了特征值分解过程,能够显著降低计算量,污染校正效果与MLE法相当。理论分析与仿真对比表明改进方法普适性强,计算量只有MLE法的万分之一,更适合工程实现。     

A two–stage approach to additive time series models

For nonlinear additive time series models, an appealing approach used in the literature to estimate the nonparametric additive components is the projection method. In this paper, it is demonstrated that the projection method might not be efficient in an asymptotic sense. To estimate additive components efficiently, a two–stage approach is proposed together with a local linear fitting and a new bandwidth selector based on the nonparametric version of the Akaike information criterion. It is shown that the two–stage method not only achieves efficiency but also makes bandwidth selection relatively easier. Also, the asymptotic normality of the resulting estimator is established. A small simulation study is carried out to illustrate the proposed methodology and the two–stage approach is applied to a real example from econometrics.     

动态死亡率下个人年金的长寿风险分析

传统的精算定价方法假定死亡率是静态的,实际上死亡率是随时间而变动的具有动态不确定性的变量。在动态死亡率的框架下定量分析长寿风险对于个人年金产品定价的影响:引入Wang转换的风险定价方法度量长寿风险的市场价格,并运用模拟分析的方法分析长寿风险对个人年金定价的影响。最后,基于分析结果,就保险公司如何管理这一风险给出建议。     

Prospects for Latin America and Caribbean Region in the Global Market for International Tourism: A Projection to the Year 2020

International tourism has become very important to several developing countries as a major source of foreign exchange earnings for their economic development. This article explores the potentials of countries of the Latin America and Caribbean region in the global market for international tourism up to the end of the next decade. This was achieved by analyzing past trends of international tourism in the region, and projecting these trends to the year 2020 using a combination of four different time‐series projection models evaluated by the mean absolute percentage error (MAPE). Results show that international tourism arrivals into the Latin America and Caribbean region would increase from 51.21 million in 2004 (end of observed period) to between 87.58 million and 100.03 million by the year 2020. The corresponding figures for international tourism receipts would go from US$34.11 billion in 2004 to between US$64.92 billion and US$75.79 billion by the year 2020. Socioeconomic impacts of these findings are given, and recommendations for marketing strategies, government public policies, and directions for future research are discussed.     

Dory & Nemo Early Learning Center

The case requires students to evaluate the current situation and growth options of a small business, Dory & Nemo Early Learning Center (D&N), which provides intergenerational programming to preschool children at a retirement home. The learning center was opened in September 2014, and it was able to make a small profit each year. However, it is projected that there would be a 75 percent decrease in net income from $8,072 in Fiscal 2016 to $1,819 in Fiscal 2017. Davis and Nathans, business partners of D&N, met to discuss the following growth options: (i) Mosaic Retirement Residences' proposal to set up two learning centers at their retirement homes each year for a total of six in three years and (ii) Harmony Retirement Residences' proposal for leasing space to set up learning centers at their retirement homes, one new learning center a year for a total of three in three years. Furthermore, Davis and Nathans had decided to increase the program fee from $320 to $350 per week for the 2017–18 academic session in September. They would also like to reduce their workload from 50 to 40 hours per week, increase their vacation time from two to three weeks, and increase their salaries and bonuses. Students must consider personal objectives of business partners and mission of D&N in the analysis. They learn to identify relevant information for decision making, apply appropriate analytical tools for quantitative analysis, integrate qualitative and quantitative factors in decision making, and make recommendations consistent with analysis.     

Varying Coefficient Regression Models: A Review and New Developments

Varying coefficient regression models are known to be very useful tools for analysing the relation between a response and a group of covariates. Their structure and interpretability are similar to those for the traditional linear regression model, but they are more flexible because of the infinite dimensionality of the corresponding parameter spaces. The aims of this paper are to give an overview on the existing methodological and theoretical developments for varying coefficient models and to discuss their extensions with some new developments. The new developments enable us to use different amount of smoothing for estimating different component functions in the models. They are for a flexible form of varying coefficient models that requires smoothing across different covariates' spaces and are based on the smooth backfitting technique that is admitted as a powerful technique for fitting structural regression models and is also known to free us from the curse of dimensionality.