Assessing circular error probable when the errors are elliptical normal

An important problem of continuing interest to engineers is the need to assess the circular error probable (CEP), a measure of the impact accuracy of a projectile or a measure of GPS point positioning accuracy. One of the challenges in addressing this problem is to construct some accurate confidence bounds or intervals for CEP in the small sample settings, where certain amount of systematic biases exist in testing experiments. Currently there is no general method available to deal with this challenge due to the intractability of the distributions of the existing CEP estimators. In this paper, in order to meet this challenge, several new approximate formulas are derived for calculating CEP, which are more accurate than the existing ones but still simple to use. Both exact and empirical expressions for the derivatives of CEP with respect to the population means and variances are also given. Using these formulas, three kinds of confidence bounds or intervals for CEP are proposed, which are based on the parametric bootstrap, the asymptotic distribution, and the Cornish–Fisher expansion, respectively. Moreover, a bias-corrected estimator of CEP is provided. The performances of these procedures are evaluated based on some Monte Carlo simulation studies. Both the theoretical and simulation results show that the Cornish–Fisher expansion-based procedure performs slightly better than the other two procedures when the downrange and cross-range variances are assumed the same. However, when these two variances are different, the simulation demonstrates that the bootstrap approach can be superior to the Cornish–Fisher for the small samples (say n=10), and vice versa for the moderate samples (say n=20).     

城乡融合发展中宅基地使用权流转的必要限制与合理扩张

宅基地三权分置改革背景下,推进农村宅基地使用权流转是大势所趋。在城乡融合发展中,宅基地使用权流转的必要限制与合理扩张是宅基地使用权流转制度发展的关键,土地增值收益公平补偿和合理共享是土地发展权分析视角的核心要义。宅基地使用权流转制度的构建需体现以土地资源可持续发展为核心的生态功能、以土地利益分配正义为核心的社会功能以及以土地财产属性彰显为核心的经济功能内涵。同时,应妥善应对土地资源利用中存在着的生态风险和社会风险。在推进农村宅基地盘活利用中,须在把握差异性的基础上适度突破限制,构建合理的宅基地增值收益分配机制以达成分配正义,完善宅基地退出补偿机制以提高农民满意度,更应注重政府干预的合理边界以减轻政策风险,从而保障农民合法的土地权益。     

中国海洋意识发展反思

海洋意识包含"重商、冒险和进取、开放和多元"三要素。以闽南人为代表的中国海洋意识和海洋发展,在历史上曾有过短暂的辉煌时期。但在大陆文化主导的明清政权压制下,中国的海洋意识和海洋发展中途夭折,未能促使商业资本主义的产生和发展。同时期西方的海洋意识则引领重商主义和资本主义的产生和发展,发展成为现代化的国家。因此,海洋意识不仅是关注海洋的物质利益,也蕴含"平等、多元、宽容"的内涵以及由此孕育的"民主、自由、人权"的理念。     

中国农村居民家庭的生育决策模型与实证分析

根据"五普"和"六普"资料,人口总和生育率显著低于世代更替水平,这表明中国人口进入了低生育水平发展阶段。关于这一问题的合理解释是除了计划生育政策影响外,农村家庭生育决策的变化可能是内生的重要影响因素。基于生育决策模型及实证分析,得出这样的结论:在土地量保持不变的条件下,农村居民家庭的生育决策主要取决于收入水平和抚养子女的成本。农村居民家庭可能会依据"量质权衡"减少生育子女,这可能是导致中国人口生育水平下降的根本原因。     

Maximizing the rate of return on the capital employed in shipping capacity renewal

Decisions regarding investments in capacity expansion/renewal require taking into account both the operating fitness and the financial performance of the investment. While several operating requirements have been considered in the operations research literature, the corresponding financial aspects have not received as much attention. We introduce a model for the renewal of shipping capacity which maximizes the Average Internal Rate of Return (AIRR). Maximizing the AIRR sets stricter return requirements on money expenditures than classic profit maximization models and may describe more closely shipping investors׳ preferences. The resulting nonlinear model is linearized to ease computation. Based on data from a shipping company we compare a profit maximization model with an AIRR maximization model. Results show that while maximizing profits results in aggressive expansions of the fleet, maximizing the return provides more balanced renewal strategies which may be preferable to most shipping investors.     

非对称信息条件下的水资源供应链库存模型研究

水量库存控制问题是水资源供应链研究的重要内容.文章以南水北调水资源供应链的子链作为研究对象,根据我国目前水资源配置的实际情况,以下游节点提出的订水量作为决策变量,研究并得出了非对称信息条件下水资源供应链的库存集中控制决策模型.     

汉语中表示数量或程度的疑问代词

通过研究现代汉语中表数量或程度的疑问代词“多”“多少”“几”“好”“偌”的使用情况,发现它们与程度副词之间的一一对应关系,并且探讨了程度副词转变为表数量或程度的疑问代词的规律。     

如何看待晚唐方镇坐大及与中央博弈问题——晚唐文学思想背景研究之一

文章主要探讨晚唐社会政治博弈整体系统中的一个侧面即方镇坐大及与中央博弈问题。晚唐方镇问题源于盛唐中唐,它由安史之乱引发但也是中央皇权主动调整统治方式的一种举措。文章把方镇坐大及与中央博弈的行为归纳为4种形式并从程度上逐一进行了分析。认为晚唐方镇问题在形式上与盛唐中唐相同但程度较轻。文中还研究了方镇之所以能够坐大及与中央博弈的原因是节度使权力（尤其军权财权和人事权）过度膨胀和少受制约。言及节度使人事权时,又重点探讨了晚唐文人与方镇及节度使的关系。在此基础上,对学界关于晚唐方镇问题的不同观点也做了辨析。     

手机阅读及其对图书馆服务的影响与拓展

通过分析手机阅读对传统阅读习惯以及信息传播的影响,提出了利用手机对传统图书馆转型的途径以及对传统图书馆的服务内容进行拓展,从而更好地满足读者个性化、多样化的需求。     

"双缺口"经济模型与中国引资模式的转变

"双缺口"经济模型主要解决发展中国家在国内资源短缺的情况下利用国外资源的问题.在对外开放初期,"双缺口"经济模型成为中国利用外资的理论依据.1992年以后,中国引进外资从数量型向集约型转变,引进和利用外资进入了一个新的阶段.虽然现阶段"双缺口"经济模型已不再是引资的理论基础,但它对开放初期中国利用外资的指导作用不能低估.