Medical rolling bearing fault prognostics based on improved extreme learning machine

Journal of Combinatorial Optimization - The problem studied in this article:the random selection of the input weight and the implicit layer bias of the extreme learning machine leads to the...     

网络广告价值的体现

正确认识信息技术给传统营销带来的革命 ,是理解新经济条件下市场营销本质和核心的基础 ;数据库的出现为现代营销提供了有力的支持 ,网络广告的有效受众通过数据库浮出水面 ;微型营销的发展 ,消费者与营销者的关系模型的变化 ,一对一的对话和交流 ,已是现代营销的关键 ,网络为广告活动搭建了一个双向的自由空间 ,网络广告在营销传播中的位置凸现 ;与新技术、新媒体、新广告相关的法律法规的出台以及行业的自律 ,是使网络广告价值最大化的有力保障     

评估供货量信息的共享在供应链管理中的价值

本文衡量了一种共享供货量信息的信息策略-即供应商向其客户(下游厂商)发布每次供货的具体数量,并通过数学建模以及模拟对此问题进行分析。结果显示,在大多数情况下,这种由信息技术支持的策略有助于供应链中的厂商适应并解决供货量不稳定的问题,供货量越是不稳定,企业越是能够从中获益。但是,当供应商及时稳定地补足缺货时,这种受益并不明显。本文的另一个发现是,供货量信息的共享可以使信息获得者受益,但是可能并不有利于发布者。也就是说,这样的信息共享能够为供应商的客户带来好处,但是供应商本身并不能因此获得显著的额外利益,反而要承担实施成本。这种不对称可能会阻碍企业间信息系统的实施,从而促使供应链成员协调信息沟通的费用,以激励供应商发布信息。我们的研究提供了对供货量信息价值进行量化的途径,同时也能够帮助供应链中的厂商评估他们在信息系统建设中的成本-收益率。     

我国新生代农民工身份认同的现状及影响因素研究

本文基于问卷调查以及半结构化访谈法,从新生代农民工的主体视角对新生代农民工群体特征、务农经验、自我认知和未来发展、对城市生活的认同度及生活消费方式等方面考察了新生代农民工的身份认同状况及影响因素。研究发现,新生代农民工有非制度化的市民身份认同心理,而该认同心理受个人收入与家庭背景、社会保障权益以及社会接纳氛围等现实因素的影响。     

Disability Among Native-born and Foreign-born Blacks in the United States

Using the 5% Public Use Micro Data Sample (PUMS) from the 2000 U.S. census, we examine differences in disability among eight black subgroups distinguished by place of birth and Hispanic ethnicity. We found that all foreign-born subgroups reported lower levels of physical activity limitations and personal care limitations than native-born blacks. Immigrants from Africa reported lowest levels of disability, followed by non-Hispanic immigrants from the Caribbean. Sociodemographic characteristics and timing of immigration explained the differences between these two groups. The foreign-born health advantage was most evident among the least-educated except among immigrants from Europe/Canada, who also reported the highest levels of disability among the foreign-born. Hispanic identification was associated with poorer health among both native-born and foreign-born blacks.     

利益集团理论与中国农民的组织化

借鉴西方利益集团理论 ,研究当前中国农民组织化过程中的问题 ,对于当前中国农民的组织化有重大的参考价值和积极的借鉴意义 ,但是应当避免采取对抗性思维来看待中国农民的组织化。同时利益集团理论也不足以完全解决中国农民的组织化问题。     

Linear or Nonlinear? Automatic Structure Discovery for Partially Linear Models

Partially linear models provide a useful class of tools for modeling complex data by naturally incorporating a combination of linear and nonlinear effects within one framework. One key question in partially linear models is the choice of model structure, that is, how to decide which covariates are linear and which are nonlinear. This is a fundamental, yet largely unsolved problem for partially linear models. In practice, one often assumes that the model structure is given or known and then makes estimation and inference based on that structure. Alternatively, there are two methods in common use for tackling the problem: hypotheses testing and visual screening based on the marginal fits. Both methods are quite useful in practice but have their drawbacks. First, it is difficult to construct a powerful procedure for testing multiple hypotheses of linear against nonlinear fits. Second, the screening procedure based on the scatterplots of individual covariate fits may provide an educated guess on the regression function form, but the procedure is ad hoc and lacks theoretical justifications. In this article, we propose a new approach to structure selection for partially linear models, called the LAND (Linear And Nonlinear Discoverer). The procedure is developed in an elegant mathematical framework and possesses desired theoretical and computational properties. Under certain regularity conditions, we show that the LAND estimator is able to identify the underlying true model structure correctly and at the same time estimate the multivariate regression function consistently. The convergence rate of the new estimator is established as well. We further propose an iterative algorithm to implement the procedure and illustrate its performance by simulated and real examples. Supplementary materials for this article are available online.     

环境污染和经济增长的关系

 环境库兹涅茨曲线暗含着“同质”假设,即随着经济的增长,各个国家和地区经历着相似的环境影响轨迹。本文在质疑该“同质”假设的前提下,对中国31个省份进行整体和分组检验,结果表明：（1）环境污染与经济增长的关系具有多种表现形态,这主要取决于地区和污染指标的选取,具体会呈现单调递减、“U”型、倒“U”型、“N”型和倒“N”型五种关系;（2）不同组别的当前经济水平会给不同污染物带来不同的内生性影响。相对而言,我国在SO2减排上的难度主要存在于高工业化高收入组、高工业化低收入组和低工业化低收入组;在固体废弃物减排上的难度主要存在于低工业化低收入组;在废水减排上的难度主要存在于低工业化高收入组和低工业化低收入组。因此,政府应当因地制宜,有针对性地提高环境规制强度、优化环境规制形式,实现环境保护和经济增长的“双赢”。     

三种国际统计质量管理框架的比较及启示

 立足于数据质量管理的现实需要,本文对国际货币基金组织、欧盟统计局及经合组织的统计质量管理框架进行比较分析。结果显示,三大国际组织的统计质量管理框架作为保证统计数据质量的有效手段,在质量维度与含义、整体框架、评估方法与工具等方面既存在明显差异又具有一致性。它们在统计质量管理方面的做法和经验对于我国加强统计数据质量管理具有借鉴意义。     

Nonparametric quasi-likelihood for right censored data

Quasi-likelihood was extended to right censored data to handle heteroscedasticity in the frame of the accelerated failure time (AFT) model. However, the assumption of known variance function in the quasi-likelihood for right censored data is usually unrealistic. In this paper, we propose a nonparametric quasi-likelihood by replacing the specified variance function with a nonparametric variance function estimator. This nonparametric variance function estimator is obtained by smoothing a function of squared residuals via local polynomial regression. The rate of convergence of the nonparametric variance function estimator and the asymptotic limiting distributions of the regression coefficient estimators are derived. It is demonstrated in simulations that for finite samples the proposed nonparametric quasi-likelihood method performs well. The new method is illustrated with one real dataset.