The population dynamics of the voleClethrionomys rufocanus in Hokkaido, Japan

Population dynamics of the gray sided-vole,Clethrionomys rufocanus, in Hokkaido, Japan were described on the basis of 225 time series (being from 12 to 31 years long); 194 of the time series have a length of 23 years or longer. The time series were classified into 11 groups according to geographic proximity and topographic characteristics of the island of Hokkaido. Mean abundance varied among populations from 1.07 to 21.07 individuals per 150 trap-nights. The index of variability for population fluctuation (s-index) ranged from 0.204 to 0.629. Another index for population variability (amplitude on log-10 scale) ranged from 0.811 to 2.743. Mean abundance and variability of populations were higher in the more northern and eastern regions of the island. Most populations, except for the southernmost populations, exhibited significant direct density-dependence in population growth. Detection rate for delayed density-dependence varied among groups from 0% to 22.6%. Both direct and delayed density-dependence tended to be stronger in the more northern and eastern populations. The proportion of cyclic populations was higher in the northern-eastern areas than that in the southern-western areas. There was a clear gradient from the asynchronous populations in southwest, to the highly synchronized populations in the northeast.     

一般约束极大极小问题的广义梯度投影算法

讨论了一类带等式、不等式约束的极大极小值问题，将其转化为带等式、不等式约束的非线性规划问题，利用辅助规划进行处理，给出了一个广义的梯度投影算法，解决了一般约束极大极小值问题。算法可在有限步达到最优点或产生一系列点列，其极限点则是最优点，并证明了该算法的全局收敛性。     

Effect magnitude: A different focus

The role of measures of effect magnitude in the research enterprise is examined. Measures of effect magnitude are used for four purposes: (a) to estimate the sample size required to achieve an acceptable power, (b) to integrate the results of empirical research studies in meta-analyses, (c) to supplement the information provided by null hypothesis significance tests, and (d) to determine whether research results are practically significant. The advantage of focusing on effect magnitude and practical significance instead of statistical significance and p values is illustrated with an example.     

Algorithms for optimal allocation of bets on many simultaneous events

Summary.  The problem of optimizing a number of simultaneous bets is considered, using primarily log-utility. Stochastic gradient-based algorithms for solving this problem are developed and compared with the simplex method. The solutions may be regarded as a generalization of 'Kelly staking' to the case of many simultaneous bets. Properties of the solutions are examined in two example cases using real odds from sports bookmakers. The algorithms that are developed also have wide applicability beyond sports betting and may be extended to general portfolio optimization problems, with any reasonable utility function.     

初始点任意优化问题的广义梯度投影法

利用广义投影与罚函数技巧和辅助规划处理带等式和不等式约束问题以及采用二阶段搜索方法，给出了一个初始点可任意的带不等式和等式约束的优化问题的广义梯度投影算法，并证明了该算法具有全局收敛性。文中削弱了文献［１］的条件，保持了它的优越性，罚参数在计算过程中自动调整且只需适当大，因此，在实际运用中不会有太大的困难。     

基于物流海拔理论的枢纽陆港布局研究

在分析陆港对进出口物流成本影响的基础上,借鉴水系理论,提出物流海拔和物流梯度的概念,并构建了物流海拔和梯度的计量模型。以中国大陆300多个城市的相关数据为依据,测算了中国大陆主要区域的物流海拔和梯度,认为中国大陆目前存在物流高原、物流平原、物流断裂带和物流谷地等典型物流地形特征。分析陆港功能与物流地形的关系,得出了枢纽型陆港布局的一般条件和原则。认为位于物流断裂带、物流谷地出口、物流平原且实力强大的中心城市具有布局枢纽型陆港的优势条件。     

裂缝性油藏压裂水平井生产动态模拟研究

研究的低渗裂缝性油藏包括基质、天然裂缝及人工裂缝,根据压裂后流体在各系统的渗流特征,建立了考虑高速非达西、启动压力梯度、毛管压力、重力作用的三重介质三维油水两相渗流数值模型,给出了其数值解法。利用研制的低渗裂缝性油藏压裂水平井生产动态模拟器分析了裂缝及储层参数对生产动态的影响。模拟结果表明,基质中启动压力梯度、人工裂缝中导流能力随时间的递减、高速非达西系数、天然裂缝渗透率、裂缝条数及裂缝长度等对压裂水平井生产动态有很大影响。要准确评价水平井压裂效果,在此类油藏压后生产动态模拟时应该考虑这些因素的影响。     

随机梯度的海岸带渔业经济影响因素分析

海岸带区域资源丰富、自然条件优越、地理位置突出并具有独特的海陆特性,已成为人类社会经济生产活动最活跃和最集中的地区。特别是海岸带渔业经济发展迅速,在海洋经济中的地位越发重要。与此同时,海岸带生态区域又承受着极大的环境生态压力,污染物排放等因素严重影响着渔业经济的发展。因此,在选取典型海岸带城市和分析其渔业产值的主要影响因素基础上,通过随机梯度算法建立海岸带渔业经济胁迫模型,采用实际数据进行了拟合,得到了各个主要影响因素,并提出了相应的对策。     

An R package and a study of methods for computing empirical likelihood

Empirical likelihood (EL) is an important nonparametric statistical methodology. We develop a package in R called el.convex to implement EL for inference about a multivariate mean. This package contains five functions which use different optimization algorithms but meanwhile seek the same goal. These functions are based on the theory of convex optimization; they are Newton, Davidon–Fletcher–Powell, Broyden–Fletcher–Goldfarb–Shanno, conjugate gradient method, and damped Newton, respectively. We also compare them with the function el.test in the existing R package emplik, and discuss their relative advantages and disadvantages.     

Some characterizations of multivariate distributions using products of the hazard gradient and mean residual life components

We give a general procedure to characterize multivariate distributions by using products of the hazard gradient and mean residual life components. This procedure is applied to characterize multivariate distributions as Gumbel exponential, Lomax, Burr, Pareto and generalized Pareto multivariate distributions. Our results extend the results of several authors and can be used to study how to extend univariate models to the multivariate set-up.