Semiparametric time series models driven by latent factor

We introduce a class of semiparametric time series models (SemiParTS) driven by a latent factor process. The proposed SemiParTS class is flexible because, given the latent process, only the conditional mean and variance of the time series are specified. These are the primary features of SemiParTS: (i) no parametric form is assumed for the conditional distribution of the time series given the latent process; (ii) it is suitable for a wide range of data: non-negative, count, bounded, binary, and real-valued time series; (iii) it does not constrain the dispersion parameter to be known. The quasi-likelihood inference is employed in order to estimate the parameters in the mean function. Here, we derive explicit expressions for the marginal moments and for the autocorrelation function of the time series process so that a method of moments can be employed to estimate the dispersion parameter and also the parameters related to the latent process. Simulated results that aim to check the proposed estimation procedure are presented. Forecasting procedures are proposed and evaluated in simulated and real data. Analyses of the number of admissions in a hospital due to asthma and a total insolation time series illustrate the potential for practical situations that involve the proposed models.     

先易后难?机会新颖性、有用性和创业者机会开发时机选择

创业是面向未来的活动,创业者如何选择创业机会开发时机是个有意义的问题.本文通过整合机会的评价维度,围绕创新性刻画机会特征,基于识解水平理论视角,通过对364名商科学生和228名创业者的两次问卷式实验,分别探究机会特征与创业者近期、远期开发意向之间的关系.结果显示,机会的新颖性和有用性会显著增加创业者的机会开发意向,但二者对应的时间距离不同:有用性对于创业者近期开发意向作用要大于新颖性,而对于远期机会开发意向新颖性的重要性要高于有用性.同时,创业者的决策逻辑会影响这一关系:效果推理能够强化新颖性对近期机会开发意向的影响,因果推理能够弱化新颖性与远期机会开发意向的关系.本文的研究结论补充了创业领域中的时间维度研究,加深了对创业者心理过程的理解,对创业者规避时间决策偏差有一定的指导作用.     

我国土地储备机构发展状况分析

通过对全国土地储备机构相关数据的分析,揭示了我国土地储备机构在时间、区域与不同城市等级上的分布情况,结合土地储备制度发展的背景,推演出我国土地储备制度发展的动力机制,即地方政府的利益诉求与国家政策推动的交互作用,并指出我国土地储备发展的重点应由机构的建立转移到内涵的丰富上。     

供应链中的信息共享与价值增值研究

以一个由一个制造商和一个分销商组成的供应链系统为背景，研究了因信息共享而带来的响应时间缩短对供应链整体及其成员收益的影响。用数理逻辑证明了供应链和其成员因信息共享而实现了价值增值。     

ARIMA计量技术下河南省农民增收的预测模型研究

笔者根据河南省1978年～2005年的农民人均纯收入统计数据,将这些数据进行平稳化、零均值化处理,并利用时间序列的自相关函数,偏自相关函数的性质,确认数据所适合的模型.通过对样本数据所做的回归拟合模型定量分析,从而为河南省"十一·五"规划提供量化指标依据.     

Feminist Ecological Economics and Sustainability

Synopsis New developments in feminist ecological economics and ecofeminist economics are contributing to the search for theories and policy approaches to move economies toward sustainability. This paper summarizes work by ecofeminists and feminist ecological economists which is relevant to the sustainability challenge and its implications for the discipline of economics. Both democracy and lower material throughputs are generally seen as basic principles of economic sustainability. Feminist theorists and feminist ecological economists offer many important insights into the conundrum of how to make a democratic and equity-enhancing transition to an economy based on less material throughput. These flow from feminist research on unpaid work and caring labor, provisioning, development, valuation, social reproduction, non-monetized exchange relationships, local economies, redistribution, citizenship, equity-enhancing political institutions, and labor time, as well as creative modeling approaches and activism-based theorizing.      

同步生物除磷脱氮新工艺探讨

近十年来,同步生物除磷脱氮一直是城市污水处理的新热点,磷氮排放标准严,除磷脱氮研究步步深入,除磷脱氮新工艺不断涌现。文章列出了当前城市污水同步生物除磷脱氮的几种新工艺流程及其一些特点,初步讨论了“工况交替”、“固液分离”和“曝气形式”有关问题。     

The Effect of the Interaction between Price and Time Preference on Cigarette Consumption among Pregnant Women

In this study, I explore smoking behavior among pregnant U.S. women using the 1979 cohort of the National Longitudinal Survey of Youth. The key aspect of this study is the availability of smoking participation data before and during pregnancy. I consider the probabilities of smoking cessation while pregnant as the outcome. I find that pregnant women who smoke are less responsive to price changes when they are more future-oriented. Women who are more present-oriented are more likely to smoke and consume more cigarettes given that they smoke more than those who are future-oriented. Moreover, those who discount the future more heavily are more sensitive to the money price of cigarettes than those who are more future-oriented. I focus on the role of time preference and the interaction between time preference and price in determining these outcomes.     

Modelling of repairable systems with various degrees of repair

The availability of a stochastic repairable system depends on the failure behaviour and on repair strategies. In this paper, we deal with a general repair model for a system using auxiliary counting processes and corresponding intensities which include various degrees of repair (between minimal repair and perfect repair). For determining the model parameters we need estimators depending on failure times and repair times: maximum likelihood (ML) estimator and Bayes estimators are considered. Special results are obtained by the use of Weibull-type intensities and random observation times.     

基于双层规划模型的冷链物流网络多目标优化

针对冷链物流时效性强这一特性,应用软时间窗反映客户满意度,并结合T.T.T理论换算货损成本。在考虑满足客户时间窗的条件下,寻找配送中心建设及操作成本、车辆成本、惩罚成本及货损成本所构成的总成本最小时的最优配送方案,建立冷链物流配送选址及路径优化的双层规划模型,并将改进的遗传算法运用到该模型中,借助Matlab软件对具体实例进行求解,得到最优结果,为冷链物流网络多目标优化问题提供理论依据。