Land pressures,the evolution of farming systems,and development strategies in Africa: A synthesis

Evidence assembled in this special issue of Food Policy shows that rising rural population densities in parts of Africa are profoundly affecting farming systems and the region’s economies in ways that are underappreciated in current discourse on African development issues. This study synthesizes how people, markets and governments are responding to rising land pressures in Africa, drawing on key findings from the various contributions in this special issue. The papers herein revisit the issue of Boserupian agricultural intensification as an important response to land constraints, but they also go further than Boserup and her followers to explore broader responses to land constraints, including non-farm diversification, migration, and reduced fertility rates. Agricultural and rural development strategies in the region will need to more fully anticipate the implications of Africa’s rapidly changing land and demographic situation, and the immense challenges that mounting land pressures pose in the context of current evidence of unsustainable agricultural intensification, a rapidly rising labor force associated with the region’s current demographic conditions, and limited nonfarm job creation. These challenges are manageable but will require explicit policy actions to address the unique development challenges in densely populated rural areas.     

Comparison of dimension reduction methods for DEA under big data via Monte Carlo simulation

Data with large dimensions will bring various problems to the application of data envelopment analysis (DEA). In this study, we focus on a “big data” problem related to the considerably large dimensions of the input-output data. The four most widely used approaches to guide dimension reduction in DEA are compared via Monte Carlo simulation, including principal component analysis (PCA-DEA), which is based on the idea of aggregating input and output, efficiency contribution measurement (ECM), average efficiency measure (AEC), and regression-based detection (RB), which is based on the idea of variable selection. We compare the performance of these methods under different scenarios and a brand-new comparison benchmark for the simulation test. In addition, we discuss the effect of initial variable selection in RB for the first time. Based on the results, we offer guidelines that are more reliable on how to choose an appropriate method.     

一种利用均匀圆阵对称特性的近场源酉变换估计算法

针对现有均匀圆阵的近场源三维参数估计算法运算量大的缺点，提出了一种基于均匀圆阵对称特性的近场源酉变换估计算法。该算法利用均匀圆阵对称特性将阵列导向矢量进行酉变换和对角化分离处理，消除距离参数，把三维搜索问题化简为二维搜索问题，同时把复值方向矢量转化为实值方向矢量。计算机仿真结果显示,所提算法估计性能优于相关序列降维估计方法，与三维多重信号分类算法性能相当，且通过矩阵分离降维和实值化处理，减少了运算量，有利于工程实时处理。     

Automatic leading indicators versus macroeconometric structural models: A comparison of inflation and GDP growth forecasting

This paper compares the forecast performance of automatic leading indicators (ALIs) and macroeconometric structural models (MESMs) commonly used by non-academic macroeconomists. Inflation and GDP growth form the forecast objects for comparison, using data from China, Indonesia and the Philippines. ALIs are found to outperform MESMs for one-period-ahead forecasts, but this superiority disappears as the forecast horizon increases. It is also found that ALIs involve greater uncertainty in choosing indicators, mixing data frequencies and utilizing unrestricted VARs. Two ways of reducing the uncertainty are explored: (i) give theory priority in choosing indicators, and include theory-based disequilibrium shocks in the indicator sets; and (ii) reduce the VARs by means of the general-to-specific modeling procedure.     

低碳偏好下三级供应链协调策略研究

以一个零售商为领导者、一个制造商和一个供应商为追随者组成的三级低碳供应链为研究对象,应用微分对策理论,考虑低碳偏好和产品商誉下研究下游零售商低碳宣传、上游制造商和供应商联合减排的低碳供应链优化与协调问题。研究发现,零售商、制造商和供应商选择何种博弈策略与三者的边际收益率有关;当供应链上三个主体的边际收益率满足一定条件时,成本分担契约可以促进零售商、制造商、供应商以及供应链系统整体的Pareto改进,使各自的最优利润得到改善,改善的程度等于成本分担的比例,而成本分担的比例取决于双方的边际收益率。最后,通过算例对模型进行了分析。     

考虑合谋和声誉的高能耗企业碳减排主体间博弈分析

在考虑企业和地方政府的声誉的基础上,分析了高能耗企业碳减排中各主体及其行为倾向,构建了中央政府与地方政府间、地方政府与高能耗企业间的博弈模型,并分析了两模型的混合策略均衡解。研究结果表明:提高中央政府的检查效率、降低检查成本、加大惩罚力度、提高声誉对地方政府和企业的影响、提高地方政府做假时需付出的伪装成本,可以有效制约地方政府和高能耗企业的欺骗及做假行为。最后,提出了提高高能耗企业减排积极性、避免企业与地方政府合谋行为发生的政策建议。     

Microfoundations

This paper argues that the microfoundations programme can be understood as an implementation of an underlying methodological principle—methodological individualism—and that it therefore shares a fundamental ambiguity with that principle, viz, whether the macro must be derived from and therefore reducible to, or rather consistent with, micro-level behaviours. The pluralist conclusion of the paper is not that research guided by the principle of microfoundations is necessarily wrong, but that the exclusion of approaches not guided by that principle is indeed necessarily wrong. The argument is made via an examination of the advantages claimed for dynamic stochastic general equilibrium models, the relationship between parts and wholes in social science, and the concepts of reduction, substrate neutrality, the intentional stance and hypostatisation.     

坚强智能电网的低碳效益与贡献率量化分析

基于低碳发展理念,我国政府已提出2020年减排目标。电网作为能源产业链的重要环节,在促进低碳发展中发挥着关键的、不可替代的作用。归纳分析了坚强智能电网促进低碳发展的各项潜在能力,采用由低碳能力到低碳效益的测评技术路线,对坚强智能电网的低碳效益进行了详细评估,分析了其低碳效益对国家减排目标的贡献率。     

我国碳金融发展的形势展望与政策建议

当前,应对气候变化已成为全球问题,其中市场机制和金融工具的作用非常关键。我国作为全球最主要的温室气体排放国之一,减排的国际压力可能继续上升。而实现国民经济的长期可持续发展,也需要经济发展方式从能源消耗模式转向低碳模式。这种长期减排的压力给我国碳金融的发展带来了机遇。但以现实条件而言,当前我国碳金融仍处于非常初级的探索阶段,为此,文章提出了短期内推动我国碳金融发展的关注重点及相关政策建议。     

碳金融对我国现代渔业经济发展支持研究

发展现代渔业经济是实现渔业经济低碳化的重要渠道。本文从碳金融的交易机制出发,参考国外银行业参与碳金融的方式和经验,结合我国渔业现状,研究碳金融对我国渔业经济节能减排支持的方法和方式,对加快我国传统渔业经济向现代渔业经济的转变路径进行探索,以期对推进现代渔业经济发展给与一定的帮助。