Spatio-temporal improvised explosive device monitoring: improving detection to minimise attacks

The improvised explosive device (IED) is a weapon of strategic influence on today's battlefield. IED detonations occur predominantly on roads, footpaths, or trails. Therefore, locations are best described when constrained to the road network, and some spaces on the network are more dangerous at specific times of the day. We propose a statistical model that reduces the spatial location to one dimension and uses a cyclic time as a second dimension. Based on the Poisson process methodology, we develop normalised, inhomogeneous, bivariate intensity functions measuring the threat of attack to support resourcing decisions. A simulation and an analysis of attacks on a main supply route in Baghdad are given to illustrate the proposed methods. Additionally, we provide an overview of the growing demand for the analysis efforts in support of operations in Afghanistan and Iraq, and provide an extensive literature review of developments in counter-IED analysis.     

包含周期变动的回归预测模型及其应用

在包含周期变动的回归预测模型基础上,在趋势分量的估计中引入了多元线性回归估计,并将此模型应用于山东省城镇居民人均生活消费的预测,提高了拟合度和预测精确度.     

一类二阶边值系统周期解的存在性

利用极小作用原理在次线性条件下证明了非自治的二阶Hamilton系统以及推广的二阶Hamilton系统周期解的存在性.     

文本翻译中文化误读的心理及阶段征象

文学文本翻译中文化误读现象在中外文化的传递和交流中普遍存在,与译者有意或无意的心理密切相关,同时这一文化现象总呈现出阶段性的征象。本文从心理、阶段征象角度探讨文本翻译中的文化误读。     

强制条件下的一类二阶Hamilton系统周期解的存在性

利用极小作用原理在强制条件下给出了一类二阶系统周期解的存在性的两个推广性的结论.     

离散型种群竞争模型的周期解

研究了一类离散型种群生存竞争模型的周期解问题。利用射影几何中常用的齐次坐标记法,把非线性系统用逐次递推的线性形式来表示,得到了判别系统有最小正周期m的周期解的一个充要条件。该结果证明了系统不存在最小正周期m=2的周期解,得出了具有最小正周期m=3的周期解时系统的一般表达式和最小正周期m=3的一个判定定理。     

Modified Restricted Almost Unbiased Liu Estimator in Linear Regression Model

In this article we introduce a modified restricted almost unbiased Liu estimator in linear regression model which satisfies the linear restrictions. The mean squared error matrix (MSEM) of the proposed estimator is derived and compared with the corresponding competitors in literature. Finally, a numerical example and a Monte Carlo simulation are given to illustrate some of the theoretical results.     

Calculating the autocovariances and the likelihood for periodic V ARMA models

This paper concerns the autocovariance calculation and likelihood evaluation for periodic vector ARMA models (PV ARMA). Based on a state space representation of PV ARMA models, we derive an algorithm for computing the PV ARMA autocovariances. The proposed method computes the autocovariances for distinct seasons separately, thereby facilitating efficient calculation for models with a large period. As a result, the obtained autocovariance calculation procedure is exploited in a periodic Chandrasekhar-type filter to evaluate the exact likelihood for Gaussian PV ARMA series. Empirical evidence shows the superiority of the periodic Chandrasekhar algorithm for likelihood evaluation over the Kalman-based one.     

Optimal investment in setup reduction for finite horizon periodic review inventory system under deterministic time varying demand

This paper examines the impact of setup reduction on a finite horizon, periodic review inventory system, under deterministic time varying demand. A total relevant cost function is developed for such systems. Using this, the impact of setup reduction is examined under various forms of setup reduction cost functions that have been suggested in the literature. The operating characteristics and optimization of the various scenarios are discussed. Our analysis shows that the effects of setup reduction in a periodic review system are similar to those in a reorder point system. Our results are likely to help practitioners who use similar periodic review systems towards decreasing total inventory related costs by investing in setup reduction.     

一类食饵具有性别结构的非自治两种群捕食系统研究

讨论了一类具有食饵补充且食饵具有性别结构、捕食者具有阶段结构的非自治捕食者-食饵系统．运用Liapunov函数方法，得到了该系统一致持续生存的充分条件．该模型的周期系统在适当的条件下存在唯一、全局渐近稳定的周期解．对更具普遍意义的概周期系统，也得出了概周期正解唯一存在且全局渐近稳定的充分条件．