On estimating the reliability after sequentially estimating the mean: The exponential case

Sequential estimation problems for the mean parameter of an exponential distribution has received much attention over the years. Purely sequential and accelerated sequential estimators and their asymptotic second-order characteristics have been laid out in the existing literature, both for minimum risk point as well as bounded length confidence interval estimation of the mean parameter. Having obtained a data set from such sequentially designed experiments, the paper investigates estimation problems for the associatedreliability function. Second-order approximations are provided for the bias and mean squared error of the proposed estimator of the reliability function, first under a general setup. An ad hoc bias-corrected version is also introduced. Then, the proposed estimator is investigated further under some specific sequential sampling strategies, already available in the literature. In the end, simulation results are presented for comparing the proposed estimators of the reliability function for moderate sample sizes and various sequential sampling strategies.     

Heterogeneous returns to chemical fertilizer at the intensive margins: Insights from Nepal

Increased fertilizer use is considered important for agricultural development in low-income countries. Promoting increased use of chemical fertilizer by lowering its price may be ineffective if demand is price inelastic. In theory, the price elasticity of demand depends on the returns to its use, but the evidence is scarce. Furthermore, while returns are often estimated for small changes in chemical fertilizer use, returns to larger changes in its use (intensive margins) are less understood. Through the inter-zonal comparisons in Nepal, we provide indicative evidence that greater returns to chemical fertilizer are associated with greater price elasticities of demand. Moreover, the evidence suggests that returns at the intensive margins, rather than returns to small changes, may largely account for inter-zonal differences in returns to chemical fertilizer within Nepal. The results suggest that better understanding the returns at the intensive margins is critical for effective agricultural inputs policies in developing countries.     

Arrow–Debreu equilibria for rank‐dependent utilities with heterogeneous probability weighting

We study Arrow–Debreu equilibria for a one‐period‐two‐date pure exchange economy with rank‐dependent utility agents having heterogeneous probability weighting and outcome utility functions. In particular, we allow the economy to have a mix of expected utility agents and rank‐dependent utility ones, with nonconvex probability weighting functions. The standard approach for convex economy equilibria fails due to the incompatibility with second‐order stochastic dominance. The representative agent approach devised in Xia and Zhou (2016) does not work either due to the heterogeneity of the weighting functions. We overcome these difficulties by considering the comonotone allocations, on which the rank‐dependent utilities become concave. Accordingly, we introduce the notion of comonotone Pareto optima, and derive their characterizing conditions. With the aid of the auxiliary problem of price equilibria with transfers, we provide a sufficient condition in terms of the model primitives under which an Arrow–Debreu equilibrium exists, along with the explicit expression of the state‐price density in equilibrium. This new, general sufficient condition distinguishes the paper from previous related studies with homogeneous and/or convex probability weightings.     

一种SAR与可见光图像压缩感知融合增强方法

针对机载多传感器成像战场态势感知的问题，提出了一种合成孔径雷达(Synthetic Aperture Radar，SAR)与可见光图像压缩感知融合增强方法。该方法首先对SAR与可见光图像分别进行压缩感知测量，得到压缩测量值，然后通过基于局部权值的融合方法实现对压缩测量值的融合，再利用有序度最优分割法提取SAR图像的强散射目标，最后对融合测量值重建得到初步融合图像，初步融合图像通过目标对比度增强得到最终融合图像。对多组图像进行了仿真分析，视觉及数值结果表明该方法能显著增强融合图像的目标对比度，提升了图像纹理清晰度，较大程度降低了图像融合过程中的数据计算量。     

Optimal insurance under rank‐dependent utility and incentive compatibility

Bernard, He, Yan, and Zhou (Mathematical Finance, 25(1), 154–186) studied an optimal insurance design problem where an individual's preference is of the rank‐dependent utility (RDU) type, and show that in general an optimal contract covers both large and small losses. However, their results suffer from the unrealistic assumption that the random loss has no atom, as well as a problem of moral hazard that provides incentives for the insured to falsely report the actual loss. This paper addresses these setbacks by removing the nonatomic assumption, and by exogenously imposing the “incentive compatibility” constraint that both indemnity function and insured's retention function are increasing with respect to the loss. We characterize the optimal solutions via calculus of variations, and then apply the result to obtain explicitly expressed contracts for problems with Yaari's dual criterion and general RDU. Finally, we use numerical examples to compare the results between ours and Bernard et al.     

Small Area Estimation for Disease Prevalence Mapping

Small area estimation (SAE) entails estimating characteristics of interest for domains, often geographical areas, in which there may be few or no samples available. SAE has a long history and a wide variety of methods have been suggested, from a bewildering range of philosophical standpoints. We describe design-based and model-based approaches and models that are specified at the area level and at the unit level, focusing on health applications and fully Bayesian spatial models. The use of auxiliary information is a key ingredient for successful inference when response data are sparse, and we discuss a number of approaches that allow the inclusion of covariate data. SAE for HIV prevalence, using data collected from a Demographic Health Survey in Malawi in 2015–2016, is used to illustrate a number of techniques. The potential use of SAE techniques for outcomes related to coronavirus disease 2019 is discussed.     

ERP软件供应商投资决策方法研究

中小企业在我国占有重要地位,但是中小企业的信息化程度并不理想,很多中小企业因为费用、员工素质等原因没有条件实施ERP软件。ERP提供商如何改进自己的投资方向,从而获得中小企业这一长尾市场的青睐,是现在ERP厂商需要考虑的问题。对江苏25个中小企业进行ERP需求的调查,并运用层次分析法,得出判断哪个方案更符合中小企业需求的方法,对ERP厂商选择方案很有意义。     

黄河流域农业用水效率及影响因素时空异质性研究

[目的]水资源短缺和农业污染严重已成为黄河流域高质量发展的主要制约因素,提高农业用水效率,对推动黄河流域生态保护和高质量发展至关重要。[方法]文章基于2009—2017年黄河流域9个省区的面板数据,运用超效率SBM模型测度黄河流域农业用水效率,发现黄河流域农业用水效率地区差异明显。为进一步分析其影响因素,采用Tobit模型和GTWR模型,分别从全局视角和微观视角对农业用水效率的影响因素进行回归分析,研究发现不同省区农业用水效率提高策略侧重不同。[结果]宁夏、内蒙古和山西农业用水效率提高的有效举措是在保障国家粮食供给安全基础上,减少高耗水作物种植面积,调整农业种植结构;甘肃提高农业用水效率的关键在于重视农业节水技术的引进、研发和应用推广;山东的出路在于提高农户节水意识;陕西和四川的有效途径在于采用科学合理的用水方式,降低农业用水占比,优化用水结构;河南和青海需要从以上各个方面进行综合考虑,以提高农业用水效率。[结论]研究黄河流域农业用水效率并探究影响各省区农业用水效率的主导因素,可以为推动黄河流域高质量发展和精准施策提供参考。     

基于熵值法的安徽省地区环境友好度分析

依据2011年数据,研究安徽省各地市环境友好度,并进行排序。结果是各地市环境友好程度参差不齐,池州市、宣城市、安庆市等地区环境友好度综合测评值显著高于淮南市、淮北市等地。淮南市、淮北市均是以煤炭为主体兼有其它多种矿产资源的城市,同时淮北市水资源又相对短缺,由于煤炭矿产资源的大量开发,造成城市生态环境恶化。而池州市、宣城市在安徽省内虽不是经济强市,但生态环境良好,经济与人口、环境协调发展。为改善各地环境友好状况,促进安徽省各地市环境友好型社会建设,应优化政府在"环境友好型社会"建设中的各种职能,优化产业结构,促进形成产业集群,促进环境税制改革,强化公众环保意识,使公众为建设环境友好型社会做出贡献。     

基于DPSIR模型的土地生态安全评价研究——以广东省佛冈县为例

针对佛冈县的土地生态的实际状况,基于"驱动力-压力-状态-影响-响应"(DPSIR)模型,构建土地生态安全评价指标体系,运用最优组合赋权法确定指标权重及土地生态安全综合评价模型对该区域进行评价。结果表明:1998—2008年佛冈县土地生态安全整体状况不断改善,生态安全综合指数从1998年的0.2567增至2008年的0.5858,生态安全水平处在从"风险级"状态转向"比较安全"状态的过程;从相关性分析来看,响应指标对土地生态安全水平的提高起主要的作用,但随着社会经济的加速发展,需要协调好各方面的矛盾,缓解资源环境的压力,使得土地生态环境朝着更好的方向迈进。