基于灰色系统理论的行业特征对高技术企业技术创新能力的影响研究——以我国2006～2008年高技术产业数据为例

本文应用灰色系统理论考察行业特征对我国高技术企业技术创新能力的影响。(1)在构建的企业技术创新能力评价指标体系的基础上,采用我国2006~2008年高技术产业数据,应用整体性灰色关联分析方法识别了影响我国高技术企业技术创新能力的主要因素和次要因素;(2)应用灰色局势决策方法对我国各高技术产业的技术创新能力进行了排序;(3)应用GM(0,N)模型量化分析了行业特征对我国高技术企业技术创新能力的影响。研究结果表明:R&D密集度、技术密集度、行业开放程度、外资企业规模比重等对我国高技术企业技术创新能力的影响相对显著,而国有企业规模比重、市场集中度、本土企业消化吸收能力等对我国高技术企业技术创新能力的影响相对较弱。根据研究结论,为提升我国高技术企业的技术创新能力,本文进一步提出了针对性的政策建议。     

我国对外直接投资的逆向技术外溢效应研究

本文选取我国对外直接投资比较集中且技术水平比较发达的九个国家(地区),利用我国和九国(地区)对外直接投资与技术创新的投入产出数据,测算我国的全要素生产率、母国和东道国的研发资本存量,实证分析了我国直接投资到这些国家(地区)所产生的逆向技术外溢程度。研究结果表明,我国通过对外直接投资渠道获得的国外研发资本存量能给母国带来正的技术外溢效应,只是由于我国对外直接投资相对吸引外资而言发展缓慢,因而其技术外溢效应相对较低。     

Estimating time-varying parameters in brand choice models: A semiparametric approach

Nowadays, brand choice models are standard tools in quantitative marketing. In most applications, parameters representing brand intercepts and covariate effects are assumed to be constant over time. However, marketing theories, as well as the experience of marketing practitioners, suggest the existence of trends or short-term variations in particular parameters. Hence, having constant parameters over time is a highly restrictive assumption, which is not necessarily justified in a marketing context and may lead to biased inferences and misleading managerial insights.In this paper, we develop flexible, heterogeneous multinomial logit models based on penalized splines to estimate time-varying parameters. The estimation procedure is fully data-driven, determining the flexible function estimates and the corresponding degree of smoothness in a unified approach. The model flexibly accounts for parameter dynamics without any prior knowledge needed by the analyst or decision maker. Thus, we position our approach as an exploratory tool that can uncover interesting and managerially relevant parameter paths from the data without imposing assumptions on their shape and smoothness.Our approach further allows for heterogeneity in all parameters by additively decomposing parameter variation into time variation (at the population level) and cross-sectional heterogeneity (at the individual household level). It comprises models without time-varying parameters or heterogeneity, as well as random walk parameter evolutions used in recent state space models, as special cases. The results of our extensive model comparison suggest that models considering parameter dynamics and household heterogeneity outperform less complex models regarding fit and predictive validity. Although models with random walk dynamics for brand intercepts and covariate effects perform well, the proposed semiparametric approach still provides a higher predictive validity for two of the three data sets analyzed.For joint estimation of all regression coefficients and hyperparameters, we employ the publicly available software BayesX, making the proposed approach directly applicable.     

Labour-market institutions, (un)employment,wages, and growth: theory and data

We analyse the implications of labour-market institutions on wage inequality in favour of skilled labour, on relative unemployment of unskilled labour, and on the economic growth rate in two clusters resulting from 27 OECD countries: Cluster 1, closely related with the Anglo-Saxon model, and Cluster 2, dominated by the Continental-European model. By linking the unskilled wage to the skilled one in Cluster 2, due to the indexation of social benefits to per-capita income, we accommodate the observed paths of the three variables in both clusters between 1991 and 2008: Cluster 1 presents a higher wage inequality in favour of skilled labour, a lower unemployment of the unskilled labour, and a better economic growth rate.     

PPP、资本流动与地区税率

本文在传统的税收竞争模型框架下引入PPP模式的设定,分析了PPP模式影响资本流动和地区税率的理论机制。理论模型发现,PPP模式会从“直接效应”和“间接效应”两个渠道影响资本流动;社会资本参与率对地区税率呈现U型影响。当参与率较低时,以间接效应为主,参与率提高将导致地区税率水平下降;当参与率较高时,以直接效应为主,参与率上升将提高本地税率。本文进一步基于中国285个地级市2006—2013年的面板数据,对理论模型进行了验证。实证结果发现,中国城市间存在普遍的税收竞争行为;PPP引入后,社会资本参与率越高,地区吸引流入的资本越多,同时也更大程度地降低了税率对资本的边际影响;社会资本参与率对地区税率影响的U型曲线临界值约为55%。     

一种鲁棒的SAR图像匹配方法

针对合成孔径雷达（Synthetic Aperture Radar,SAR）图像匹配中虚假匹配和鲁棒性欠缺的问题,提出了一种鲁棒的SAR图像匹配方法。首先通过正射校正来进行预处理,从而消除SAR图像的旋转;然后利用相关匹配方法初步提取同名点;最后根据同名点的空间位置来筛选同名点并计算仿射矩阵进行匹配,提高了SAR图像匹配的精度和鲁棒性。实验证明了所提方法的有效性。     

利用曲波变换和局部线性嵌入算法的SAR图像海面油膜特征提取

溢油事故带来的海洋污染问题日益严重,SAR图像快速准确地自动识别为溢油事故的处理和决策支持提供了重要前提。为了获得更高的油膜识别准确率,提出了一种基于曲波变换（Curvelet）和局部线性嵌入（Local Linear Embedding,LLE）算法的SAR图像特征提取方法。首先,利用Curvelet对图像进行分解,选取包含了主要信息的低频分量作为新的图像矩阵;然后,利用LLE进行非线性降维,提取图像分类特征。为了验证提取特征的有效性,所提的Curvelet-LLE算法与PCA、LLE、等距特征映射（Isomap）、Curvelet变换和 Fisher 判别分析(Curvelet-KFD)、Wavelet-LLE等特征提取算法,利用K最近邻和支持向量机分类器分别进行了对比实验。实验结果表明,Curvelet-LLE算法能更有效地提取SAR图像油膜识别的分类鉴别特征,其准确率相对较高,具有较好的实用性。     

基于SDN和MEC的5G VANET架构及其性能分析

为了在大规模的车载自组织网络（Vehicular Ad-hoc Network,VANET）中提供灵活的网络管理、控制和提高资源利用率,结合软件定义网络（Software Defined Network,SDN）、云无线接入网络（Cloud Radio Access Network,C-RAN）和移动边缘计算（Mobile Edge Computing,MEC）,提出了一种分层的5G VANET架构（5G MEC VANET）,能够支持智能交通系统各种功能和应用的动态特性,同时降低网络管理成本。此外,位于网络边缘的MEC框架避免了车辆与路边基站的频繁交互,减少了数据传播延时。仿真结果表明,与传统VANET和5G VANET架构相比,所提出的架构降低了传播时延,提高了网络带宽吞吐量,同时减少了控制器开销。     

利用最小冗余最大相关和SVM的SAR图像海上溢油识别

近年溢油事故频发,海洋污染日益严重。利用合成孔径雷达（SAR）卫星可以有效跟踪由海上溢油事故导致的油膜扩展情况。利用最大冗余最小相关-支持向量机（mRMR_SVM）算法进行SAR图像溢油识别,为溢油事故决策支持提供重要前提。首先采用mRMR提取最优特征向量集,对输入值进行降维; 然后采用SVM算法解决油膜图像分类问题,同时选择径向基函数（RBF）为核函数;使用训练集训练该模型,调整模型参数;以测试集特征向量作为输入,利用训练好的模型进行溢油识别。实验结果表明,mRMR_SVM模型对SAR图像的油膜和类油膜识别有效,准确率为96.875%.     

Fashionable food: a latent class analysis of social status in food purchases

A framed field experiment combined with a latent class econometric approach was used to investigate how prestige-seeking behaviour influences food choices. We propose a theoretical framework to test conspicuous consumption of specialty food products. We test the hypothesis empirically by categorizing individuals into unobserved latent classes according to their general prestige-seeking behaviour. We find evidence of food consumption driven by prestige to the point of becoming a symbol of social status. The prestige-seeking behaviour seems to be motivated by invidious comparison or higher-class individuals seeking to differentiate themselves from lower-class individuals; and pecuniary emulation, or lower-class individuals buying prestigious goods in order to be perceived as members of a higher class. Findings from this study revealed that the effects of differentiating labelling attributes had a higher impact for individuals classified into classes with prestige-seeking behaviour to attain an elevated social status.