知识视角下区域创新绩效研究——基于PCA-DEA模型和Malmquist指数的实证分析

本文综合关于区域创新绩效的研究文献,构建了知识视角下的区域创新绩效指标评价体系。在此基础上,首次运用PCA-DEA模型和Malmquist指数分析方法对我国30个省域创新绩效进行了动态实证分析。研究发现我国区域创新绩效整体呈上升趋势,但是近年遇到瓶颈,区域创新效率的主要限制因素是PECH（纯技术效率）值较低。东部区域创新绩效高于西部地区,而中部区域创新绩效最低。西部地区创新技术效率已经赶超东部,呈持续领先态势。北京、内蒙、福建、河南、贵州、云南、宁夏、新疆等8个省市是创新活动生产可能性前沿外移的主要推动者。基于实证分析的结果,为提高我国区域创新绩效提供相应思路。     

Induced Innovation in U.S. Agriculture: Time-series, Direct Econometric, and Nonparametric Tests

The hypothesis of induced innovation is tested for U.S. agriculture using a high-quality state-level panel data set and three disparate testing techniques—time series, direct econometric, and nonparametric. We find little support for the hypothesis. That conclusion is robust across testing techniques. However, as with all empirical tests of this hypothesis conducted to date, ours focus only on the demand side of the hypothesis. The hypothesis could have been rejected simply because the marginal cost of developing and implementing input-saving technologies for the relatively expensive inputs is greater than for the relatively cheap inputs.     

传感器系列课程教学改革实践与探索

在传感器系列课程的教学、实验、设计等教学环节中进行教学改革,将知识传授、能力培养、素质教育融为一体,提高了学生的学习兴趣,获得了较好的工程实训效果。     

Evolving splines and seasonal unit roots in weekly agricultural prices

The univariate statistical properties of agricultural price series need to be examined as a first step in the analysis of price transmission mechanisms. However, in the case of weekly price series, increasingly available, the testing procedures usually applied in this step are not suitable to deal with evolving seasonal effects. In this study, a method of testing for seasonal unit roots in weekly series of agricultural prices is described. When the deterministic seasonal component does not remain constant over time, the restricted evolving spline model (RESM) is shown to be a useful parametric formulation to capture the deterministic seasonal pattern. Therefore, the RESM model should be included as a deterministic component in auxiliary regression for unit root tests at seasonal frequencies. This proposal is applied to three weekly series of Canary Islands banana prices. From the standard seasonal unit root tests, the null hypothesis is failed to be rejected at the 5% or 10% significance level at some seasonal frequencies for each one of the series. Once critical values are obtained by simulation exercises when the RESM model is included, the hypotheses of unit root are rejected at each one of the seasonal frequencies for all of the three series.     

Regulation of relationships between heterogeneous farmers and an aquifer accounting for lag effects

Many environmental problems are due to damage caused by pollutants that accumulate with a time lag following their emission. In this study, we focus on nitrates used in agriculture, which can pollute groundwater many years after their initial application. A dynamic optimal control problem with heterogeneous farmers is proposed. The usual structural parameters such as the discount rate, the natural clearing rate and the lagged time interval between the occurrence of soil‐level pollution and the impact on groundwater are taken into account. We also examine pollution as caused by a continuous set of farms characterised by their individual performance index and by their individual marginal contribution to the pollution. The issue is further investigated by taking account of change in the information context, successively related to perfect information and to asymmetric information. As a result, when the delay between the spreading of N‐fertilizer and the impact on the aquifer increases, that is, the longer the lag, the steady‐state pollution stock and the steady‐state shadow price of the stock both increase. Moreover, we show that the optimal regulation may require a decreasing amount of fertilizer over time, even in the case of initial underpollution.     

Perspectives on Natural Resources in the Global Economy: Polity Series Review

Polity's ‘Resources’ series is a set of scholarly books, each of them dealing with a single resource or resource‐based commodity from a generally global or international perspective. As of this writing, nine books have been published in the series, six of which I review here. The series is a welcome contribution to interdisciplinary and overall critical perspectives on the social and environmental dimensions and implications of the international appropriation, production and exchange of natural resources. While there is no clear disciplinary bent or theoretical foundation running across the volumes, together the books develop a transnational perspective, stressing the linkages between specific sites of appropriation and production, on the one hand, and broader political economic networks of processing, finance, coordination, commercial distribution and social regulation, on the other. The books should serve as valuable references to researchers in academic, government and non‐government institutional settings, but should also prove valuable for undergraduate teaching on contemporary natural resource industries and their social regulation.     

正交多载波调制(OFDM)技术及其应用

本文首先介绍了正交多载波调制（OFDM）技术适用于高速数据传输的原理,着重讨论了OFDM基于FFT算法在基带实现多载波调制的原理和OFDM中的同步问题,最后对OFDM在宽带无线数据传输中的应用作了初步展望。     

基于PCA/FCM的企业信用评价研究

针对我国企业信用评价问题的特点,文章分析了企业信用评价基本原则和主要影响因素,建立了企业信用评价指标体系。企业信用评价是一类包括一系列独立变量的分类问题,将主成分分析与模糊理论引入信用评价中,构建基于PCA/FCM的企业信用评价模型,这使得模型更接近人们的思维方式、指标赋权更为客观。应用该模型及SPSS11.0、MATLAB7.0对所选企业研究显示:该模型非常有效和实用。     

贫困、经济增长与脱贫时间:基于中国城镇居民调查数据的分析

贫困指数是衡量社会总体贫困程度的指标,在众多的贫困指数中.本文选择具有良好性能的瓦特指数和由此派生出来的脱贫时间指数,分析了我国城镇上个世纪90年代以来的贫困变化趋势.研究发现,城镇贫困在1997年达到高峰,然后逐渐缓和;贫困人口的收入增长在初期能使脱贫时间迅速下降,但边际效果是递减的;贫困人口之间的收入分配不平等延长了脱贫时间:如果贫困人口的初始收入增加,会明显降低脱贫时间.     

Riding the Ever-Rolling Stream: Time and the Ontology of Violent Conflict

In this paper, we examine the ways in which the passage of time is dealt with in econometric studies of violent conflict and civil war with empirical attention to the dynamics of ethnic conflict. We argue that the mainstream approach to econometric studies of civil war is based on a time-invariant ontology and that this is not an appropriate or adequate way of capturing the causal patterns of violent conflict. Based analysis of replication datasets using structural break analysis and rolling windows, we show how careful attention to the passage of time reveals important macro-historical changes in the coefficients on ethnic diversity in explaining conflict incidence. We conclude that econometric studies of civil war need to pay more careful attention to the limitations on the generalizations that they draw through attention to the passage of time and better iteration with qualitative and historical studies.