块Jacobi迭代阵的收敛性

研究大型线性方程组迭代解法中分块ＪＡＣＯＢＩ迭代阵的收敛性。采用块矩阵分析方法和谱半径降维估计法得到块Ｊａｃｏｂｉ迭代阵收敛的实用充分条件。     

网络密度、高管注意力配置与企业绿色创新:制度压力的调节作用

本文整合社会网络理论、注意力基础观和新制度主义理论等,通过对282家制造企业的问卷调查,采用多元回归分析方法,探讨了网络密度和高管注意力配置的交互匹配对企业绿色创新的影响机制,以及制度压力在其中的调节作用。研究发现,在高密度网络中,高管采用注意力聚集策略对绿色创新有显著正向影响;而在低密度网络中,高管采用注意力分散策略对绿色创新有显著正向影响。规制压力和模仿压力均正向调节网络密度和高管注意力配置的交互作用对绿色创新的影响,但模仿压力的调节作用更强。通过构建不同制度压力情景下网络密度与高管注意力的交互作用对绿色创新影响的理论框架,本文推动社会网络理论、注意力基础观等成熟的理论成果从一般创新向绿色创新研究领域繁衍,为企业绿色创新加入与主流理论的对话做了努力,为企业在绿色创新过程中根据不同的制度压力,以及所嵌入的组织间网络密度情况,选择合适的注意力配置策略提供理论参考。     

过度旅游的综合评价方法及其实证研究

针对过度旅游对旅游目的地造成紊乱的问题,对过度旅游的成因及危害进行总结分析,利用统计数据确定综合旅游密度、旅游强度、民宿密度3项判断过度旅游状态的指标,并将3项指标分数之和作为评价过度旅游的指标值; 使用Zipf分布双对数图与H/T断裂点法确定数据等级划分方式,采用定距分数累加方式建立过度旅游综合评价方法; 利用国内外代表性旅游城市的数据进行了实证分析,验证了所建立综合评价方法的可行性。研究认为,过度旅游综合评价分数给出了旅游目的地过度旅游程度的相对顺序,能够推测各样本过度旅游风险所对应的要素,为制定过度旅游对应政策的优先级提供参考; 在样本城市中,国外过度旅游目的地注重流量管控、征收旅游税等三四级对策,而中国过度旅游目的地注重景区保护和流量管控等二三级对策,尽管国内样本城市旅游服务负荷已高于部分发达国家,但未出现排斥游客的过度旅游现象; 国内仍需要利用经济手段避免部分地区的旅游业依赖,升级城市景区保护为城市全域保护,适时推进旅游税政策。     

Approximation of density functions by orthogonal series with grouped data

Summary Letg(x) andf(x) be continuous density function on (a, b) and let {ϕ_j} be a complete orthonormal sequence of functions onL ₂(g), which is the set of squared integrable functions weighted byg on (a, b). Suppose that over (a, b). Given a grouped sample of sizen fromf(x), the paper investigates the asymptotic properties of the restricted maximum likelihood estimator of density, obtained by setting all but the firstm of the ϑ_j’s equal to0. Practical suggestions are given for performing estimation via the use of Fourier and Legendre polynomial series. Research partially supported by: CNR grant, n. 93. 00837. CT10.     

A simple,automatic and adaptive bivariate density estimator based on conditional densities

The standard approach to non-parametric bivariate density estimation is to use a kernel density estimator. Practical performance of this estimator is hindered by the fact that the estimator is not adaptive (in the sense that the level of smoothing is not sensitive to local properties of the density). In this paper a simple, automatic and adaptive bivariate density estimator is proposed based on the estimation of marginal and conditional densities. Asymptotic properties of the estimator are examined, and guidance to practical application of the method is given. Application to two examples illustrates the usefulness of the estimator as an exploratory tool, particularly in situations where the local behaviour of the density varies widely. The proposed estimator is also appropriate for use as a pilot estimate for an adaptive kernel estimate, since it is relatively inexpensive to calculate.     

A Unified Approach to the Approximation of Multivariate Densities

Approximation of a density by another density is considered in the case of different dimensionalities of the distributions. The results have been derived by inverting expansions of characteristic functions with the help of matrix techniques. The approximations obtained are all functions of cumulant differences and derivatives of the approximating density. The multivariate Edgeworth expansion follows from the results as a special case. Furthermore, the density functions of the trace and eigenvalues of the sample covariance matrix are approximated by the multivariate normal density and a numerical example is given     

基于iCARE理论的《大学英语》课程定位研究与教改实践

《大学英语》是高校一门重要的公共基础课,厘清课程性质是推进教学改革的基础。在梳理不同时期《大学英语》教学大纲有关规定,借鉴国外高校现代语言课程定位基础上,提出《大学英语》课程定位是EGP,提高"交互密度"是保证学习效率和效果的关键。河北科技大学在多年教改实践基础上,创建了iCARE教学理论,并从六个方面推进《大学英语》课程改革,形成具有校本特色的《大学英语》教学模式,取得良好教改成效。     

Statistical inference for a relaxation index of stochastic dominance under density ratio model

Stochastic dominance is usually used to rank random variables by comparing their distributions, so it is widely applied in economics and finance. In actual applications, complete stochastic dominance is too demanding to meet, so relaxation indexes of stochastic dominance have attracted more attention. The π index, the biggest gap between two distributions, can be a measure of the degree of deviation from complete dominance. The traditional estimation method is to use the empirical distribution functions to estimate it. Considering the populations under comparison are generally of the same nature, we can link the populations through density ratio model under certain condition. Based on this model, we propose a new estimator and establish its statistical inference theory. Simulation results show that the proposed estimator substantially improves estimation efficiency and power of the tests and coverage probabilities satisfactorily match the confidence levels of the tests, which show the superiority of the proposed estimator. Finally we apply our method to a real example of the Chinese household incomes.     

京津冀人口集聚对能源消费的影响

京津冀作为我国重要的人口集聚区,其区域发展面临严重的能源和环境问题。首先,基于STIRPAT模型构建京津冀面板数据模型,研究1990—2017年京津冀人口密度、经济增长、产业结构和环境规制对能源消费的影响。其次,采用SVAR模型通过脉冲响应函数和方差分解,研究京津冀人口密度变动对能源消费的作用机理和动态影响关系。结果显示,京津冀三地的人口密度、人均实际GDP与能源消费之间存在正向影响关系,其中河北省影响系数最大;北京和天津第三产业占比与能源消费之间存在反向影响关系,河北省第三产业占比对能源消费的影响不显著;北京和天津的环境规制对能源消费影响不显著,河北省环境规制对能源消费具有正向影响;京津冀地区和京冀两地人口密度变动对能源消费的影响在短期呈现负向效应,但是在中长期京津冀地区和三地人口密度变动对能源消费的影响均先上升然后缓慢下降,人口集聚具有集约用能效应。相对于能源消费自身影响而言,京津冀人口密度变动对能源消费的贡献相对较小,其影响效应有限。最后,对京津冀人口流动和能源消费一体化协同发展提出对策建议。     

具有不同偏好网络结构的群体评价信息集结方法

以评价者为节点,评价者之间偏好相似性测度为连接的网络为群体偏好网络,讨论了评价群体在偏好网络均衡状态时3种不同网络结构(星形网络、闭链结构和完整网络)的群体评价信息集结方法,将具有网络结构信息的节点数据转化为平面数据,提出了平面密度加权平均算子和平面密度加权几何平均中间算子。给出了平面数据的划分方法及平面密度算子的趋同性测度,并将算子应用于各网络结构的评价群体评价问题。