天然气产量季节预测模型的比较与选择

随着气田企业规模的扩大和竞争的加剧,需要建立一套完整的短期天然气产量预测方法及模型,以预测未来的产量发展趋势,故提出三种基于时间序列预测模型:布朗指数平滑法(Smooth)、季节系数法时间序列的预测、用于时间序列的灰色系统预测方法.但是普通时间序列预测模型的参数难以估计并且模型较难预测具有季节特征的时间序列问题,根据天然气产量的季节性、周期性特点,实验结果表明:季节系数法时间序列的预测能够对带有季节特征的历史数据进行有效预测,对进行气田企业的安全生产都具有一定的理论和实践价值.     

The Methuselah Effect: The Pernicious Impact of Unreported Deaths on Old-Age Mortality Estimates

We examine inferences about old-age mortality that arise when researchers use survey data matched to death records. We show that even small rates of failure to match respondents can lead to substantial bias in the measurement of mortality rates at older ages. This type of measurement error is consequential for three strands in the demographic literature: (1) the deceleration in mortality rates at old ages; (2) the black-white mortality crossover; and (3) the relatively low rate of old-age mortality among Hispanics, often called the “Hispanic paradox.” Using the National Longitudinal Survey of Older Men matched to death records in both the U.S. Vital Statistics system and the Social Security Death Index, we demonstrate that even small rates of missing mortality matching plausibly lead to an appearance of mortality deceleration when none exists and can generate a spurious black-white mortality crossover. We confirm these findings using data from the National Health Interview Survey matched to the U.S. Vital Statistics system, a data set known as the “gold standard” (Cowper et al. 2002) for estimating age-specific mortality. Moreover, with these data, we show that the Hispanic paradox is also plausibly explained by a similar undercount.     

Trends in bird species richness,abundance and biomass along a tropical urbanization gradient

Impacts of urbanization on biodiversity are commonly studied using urbanization gradients which provide a space-for-time substitution in estimating consequences of urban expansion. Rates of urbanization and human population growth are high in tropical countries of the developing world, which also hold most of the world’s biodiversity hot-spots, yet few studies have considered biodiversity trends along urban gradients in these regions. Bird communities across a gradient of nine sites in Uganda, from the city centre of Kampala to outlying rural locations, were studied over a six year period. These sites were ordered along an urbanization gradient using Principle Components Analysis based on habitat variables estimated at each site. Bird species richness showed a decrease from rural to urban sites, a trend especially evident in forest birds. There was no clear pattern in total abundance, total biomass or biomass per individual along the gradient. However, this latter result was heavily influenced by a colony of Marabou Storks at one site. When this species was omitted, there was evidence of a positive trend with urbanization, showing that as species richness decreased, the bird community was increasingly dominated by larger species with increasing urbanization, which were mainly scavengers able to exploit human refuse. These results provide further support for the negative impacts of urbanization on species richness, but also demonstrate trends in abundance and biomass are variable across different regions. In particular, the increasing dominance of larger species in urban areas may be relevant to certain geographic and/or socioeconomic contexts.     

Women’s attitudes towards the medicalization of childbirth and their associations with planned and actual modes of birth

Problem

Rates of medical interventions in childbirth have greatly increased in the Western world.

基于突发群体事件预防的高校网络舆情管理

高校的稳定对于社会的稳定具有重要意义。从国际和国内经验来看,移动互联网改变了高校的网络舆情环境,因而给突发群体事件的预防及高校的稳定带来了新的挑战。移动互联网下的高校网络舆情影响力、参与积极性、突发性及冲击力都大大提升,针对其进行的管理呈现有效处置周期更短、官方舆论引导能力更弱、管控复杂程度增加且容易出现群体极化行为等特点,高校应从组织管理体系、线下沟通机制、舆情信息处理机制、危机应急处理机制、网络舆情管理队伍、网络道德文化等多个方面进行综合治理,从而改善高校网络舆情管理,更好地预防突发群体事件的发生。     

外商直接投资对中国高新技术产业国际竞争力的影响

基于国际贸易理论中外商直接投资对一国产业国际竞争立提升的理论,通过协整检验的计量方法具体分析了外商直接投资对中国高新技术产业总体国际竞争力及对中国主要出口的三种高新技术产品的国际竞争力的影响程度。结果表明,外商直接投资对中国计算机技术、通信技术和电子技术等三类高新技术产品出口竞争力有很强的正向作用。因此,继续吸引外商投资,可以较好的提升中国高新技术产业的国际竞争力。     

高校工资管理存在的问题及对策研究

工资管理是高校管理工作中一项很重要的内容。工资不仅关系到每个教职工的切身利益,也关系到高等学校的稳定和发展。通过介绍高等学校工资管理工作的发展历程,分析了高校工资管理中存在的问题,并提出了改革工资管理的思路与对策。     

加快西部地区特色经济发展的区域优势分析

本文对区域特色经济的基本理论进行了系统的论述,在以区域经济相关理论对区域特色经济进行理论分析的基础上,论述了西部地区发展特色经济的现状及基本思路,即将西部地区的资源禀赋潜在优势转化为现实的经济优势,依托比较优势,发展特色经济,走区域经济特色化的道路。     

日本和德国的环境工程专业教学模式介绍

从环境工程专业教学特点、时代需求出发,介绍了日本和德国环境工程专业本科教学课程设置及实践性环节的基本情况和主要特色,对我国环境工程专业的教学改革和人才培养规划有一定的借鉴意义。     

中国IT企业领导者胜任力模型及其对企业绩效的影响

基于领导者胜任力模型,结合IT企业员工特征,构建出符合IT企业的领导者三维度胜任力模型;通过对国内八家IT企业中高层管理者及核心员工问卷调查,考察了IT企业领导者胜任力模型对企业绩效的影响机制.结果表明,员工心理资本在领导者胜任力要素与企业绩效之间起中介作用,IT企业领导者个人特质、管理能力、专业能力通过心理资本与企业绩效正相关,其中管理能力相关系数较大,对企业绩效影响显著.