Privacy Quantification Model Based on the Bayes Conditional Risk in Location-Based Services

The widespread use of Location-Based Services(LBSs),which allows untrusted service providers to collect large quantities of information regarding users’locations,has raised serious privacy concerns.In response to these issues,a variety of LBS Privacy Protection Mechanisms(LPPMs)have been recently proposed.However,evaluating these LPPMs remains problematic because of the absence of a generic adversarial model for most existing privacy metrics.In particular,the relationships between these metrics have not been examined in depth under a common adversarial model,leading to a possible selection of the inappropriate metric,which runs the risk of wrongly evaluating LPPMs.In this paper,we address these issues by proposing a privacy quantification model,which is based on Bayes conditional privacy,to specify a general adversarial model.This model employs a general definition of conditional privacy regarding the adversary’s estimation error to compare the different LBS privacy metrics.Moreover,we present a theoretical analysis for specifying how to connect our metric with other popular LBS privacy metrics.We show that our privacy quantification model permits interpretation and comparison of various popular LBS privacy metrics under a common perspective.Our results contribute to a better understanding of how privacy properties can be measured,as well as to the better selection of the most appropriate metric for any given LBS application.     

基于贝叶斯方法的Meta-分析

本文基于贝叶斯Meta-分析给出了Jeffreys无信息先验B(1/2,1/2)时的链接分布,并将其进行推广,给出了先验分布为B(α,β)时的链接分布。     

航班运行风险网络的传播与控制改进

为探究航班运行风险的产生、传播与控制过程, 首先统计华北区域航班运行数据共计76个风险节点。然后，采用偏秩相关系数构建风险网络, 再使用社团模块探测算法与三角最大滤波法验证网络适用性。并且, 提出一种适用于航班运行风险分析的SEIR(susceptible-infected-exposed-recovered)模型。根据动力学传播结果, 聚类定位网络传播中关键节点。最后, 采用前置预防与战术处置两类控制方案。计算结果表明，仅控制5个节点后, 感染峰值可降低18.44%, 峰值时间推后两个周期, 起降等重要操纵节点被感染次数平均下降11.74%。该方案在感染峰值、感染周期、重要节点感染3个方面的抑制效果均占优。以上结果证实, 所提方案可有效用于航班运行风险问题分析。     

Mechanical behavior of a near α titanium alloy under dynamic compression: Characterization and modeling

Dynamic compression tests under strain rates from 870 s^?1 to 2100 s^?1 were conducted for a near α Ti–8Al–1Mo–1V titanium alloy with equiaxed microstructure. Compression behavior, adiabatic shearing and band microstructure were investigated via characterization and calculation. The results demonstrate that all dynamic constitutive curves exhibited obvious stress fluctuation phenomenon with double increase-decrease changing stages at the primary stage of compression. The dislocation multiplication theory can be used to explain this phenomenon. After the stress fluctuation period, work hardening coexisted with the thermal softening, resulting in the slow hardening tendency in constitutive curves. J-C model was utilized to quantify the dynamic constitutive curves. The deviations between the predicted and experimental curves under high strain rates may be attributed to the over-consideration of thermal softening effect in J-C model. Adiabatic shearing band (ASB) began to form under the strain rate of 2100 s^?1. A total shearing strain of 8.1 within ASB achieved in 8.9 μs, corresponding to a local strain rate of about 9.1 × 10⁵ s^?1 and is over 430 times of the macro strain rate. Post annealing was conducted on ASB before EBSD characterization. Due to the static recrystallization during annealing, the α phase within ASB generally presented as ultra-fine grains less than 1 μm in diameter.     

省级公共医疗卫生供给绩效评估实证研究——基于全面绩效管理的视角

为了研究安徽省公共医疗卫生供给绩效及其影响因素,从公共服务供给压力、状态和响应3个维度筛选了15个相关指标,构建了评估指标体系,利用最新数据和熵值-Tobit模型对安徽省公共医疗卫生供给绩效及其影响因素进行综合评估,认为样本考察期内安徽省公共医疗卫生供给绩效呈现"快速-平稳-快速-平稳"的动态波动趋势,且供给压力依然较大,供给状态不容乐观,但供给响应指数提升明显; Tobit回归显示,安徽省财政医疗支出占比呈现规模报酬递减效应,人口密度与公共医疗卫生供给绩效呈现负相关关系,而人均地区生产总值、城镇化水平和财政自给率与公共医疗卫生供给绩效呈现正相关关系,但财政自给率的影响不显著,据此,提出了促进省级公共医疗卫生供给绩效提升的相关对策建议。     

基于聚类方法和神经网络的非线性系统多模型自适应控制

针对具有参数跳变的非线性系统,联合聚类算法和神经网络提出新的多模型自适应控制方法。首先对系统的输入输出数据进行模糊聚类,然后基于递推最小二乘法建立多个固定模型。为提高系统的暂态性能,同时建立两个自适应模型,并在此基础上设计鲁棒自适应控制器。此外,为了补偿系统的非线性部分,建立非线性预测模型,并设计非线性神经网络自适应控制器。所提方法可使控制切换系统具有稳定性保证。最后,通过性能指标对控制器进行平滑切换。仿真结果表明,所提方法能够保证系统具有良好的控制性能。     

高新技术企业创新资金配置风险预警的FOA-SVM模型及实证

为了提高创新资金的运营效率和为企业创新活动提供有效支撑,按照高新技术企业创新资金配置的生态化要求,从资金的来源、使用、偿还、收益分配四个维度进行风险分析并构建风险预警指标,给出创新资金配置的生态目标,将支持向量机二分类问题扩展到多分类并与果蝇优化算法结合构建风险预警的FOA-SVM (fruit fly optimization algorithm and support vector machines)模型,确定警度和警限,选取117家医药制造企业2016年数据进行模型验证并与GA-SVM (genetic algorithm and support vector machines)模型进行比较分析,研究表明,FOA-SVM模型分类准确率高而且对于高风险的误判率低,可以实现对高新技术企业创新资金配置风险的分类预警,为优化创新资金配置、防范与控制创新资金配置风险提供依据.     

基于LE-PO法的特高频输电线路无源干扰求解

基于输电线路无源干扰面模型,提出了采用大面元物理光学法(Large Element-Physical Optics,LE-PO)对特高频无源干扰水平进行求解的思想.根据LE-PO法的假设,对电场积分方程进行了简化.当激励源为平面波时,采用LP-RWG(Linearly Phased-Rao Wilton Glisson)基函数对铁塔表面感应电流进行离散,推导了输电线路铁塔散射场求解的表达式.采用相关文献算例分析了LE-PO法求解输电线路无源干扰时的计算精度和计算资源.研究表明,LE-PO法的求解精度与PO法一致,但能节省大量的计算资源.     

基于差价补偿策略的集装箱班轮运输定价模型

针对集装箱班轮运输定价问题,构建差价补偿策略下班轮运输的定价模型,研究差价补偿策略下托运人订舱行为和承运人定价决策,分析市场需求波动与承运人定价、差价补偿系数、承运人收益的内在关系,以及承运人定价对托运人订舱量的影响,并通过数值分析进行验证.结果表明:随着市场需求波动的增大,承运人最优定价与最大收益降低,而差价补偿系数增大;且托运人订舱量随着承运人定价的增大而减少.承运人采用差价补偿策略时,市场需求波动存在一个上限值,如果需求波动小于该值,则承运人采用差价补偿策略有利于其提高收益.     

A Simple Linear Regression Approach to Modeling and Forecasting Mortality Rates

Observing that a sequence of negative logarithms of 1‐year survival probabilities displays a linear relationship with the sequence of corresponding terms with a time lag of a certain number of years, we propose a simple linear regression to model and forecast mortality rates. Our model assuming the linearity between two mortality sequences with a time lag each other does not need to formulate the time trends of mortality rates across ages for mortality prediction. Moreover, the parameters of our model for a given age depend on the mortality rates for that age only. Therefore, whether the span of the study ages with the age included is widened or shortened will not affect the results of mortality fitting and forecasting for that age. In the empirical testing, the regression results using the mortality data for the UK, USA and Japan show a satisfactory goodness of fit, which convinces us of the appropriateness of the linear assumption. Empirical illustrations further show that our model's performances of fitting and forecasting mortality rates are quite satisfactory compared with the existing well‐known mortality models. Copyright © 2015 John Wiley & Sons, Ltd.