路基稳定性数值分析

本文通过对常见的路基稳定性分析案例进行强度折减法的数值分析,为进一步研究这一方法在路基稳定性分析中的应用奠定基础。     

Pure meat – Public perceptions of risk reduction strategies in meat production

Experience has shown that both the assessment and implementation of new technologies in food production are challenged by negative assessments of the technologies by the public. This article seeks to deepen our understanding of the concerns that may underlie negative attitudes to various kinds of risk reduction strategy in meat production, with the aim of distinguishing between forms of risk reduction in terms of their acceptability. The paper reports the result of a focus-group study. Six focus groups with Danish citizens (N: 5–9) were conducted during May 2006. The design of the groups took a bottom-up approach and included elements of meat quality, meat safety and risk reduction strategies. The study shows the dilemma risk reduction presents to members of the public. On the one hand, people want safe meat; on the other, the study showed that with the exception of hygiene practices, people generally have an aversion to risk reduction strategies. Some variation was found, however, in the rejection of the strategies. Thus, more acceptable strategies are characterised by a low degree of technological interference, and by being close to the consumer’s experience in everyday life and/or familiar to the participants’ picture of meat production. It is also important that the strategy does not alter the quality of the end-product (meat) in an unfavourable way. The implications of the results and the inherent dilemma for meat safety policy formation are discussed.     

Auction winning,social dynamics and non-compliance in a payment for ecosystem services scheme in Indonesia

Conservation auctions for payment for ecosystem services (PES) are useful to identify the levels of incentives that will cover the opportunity costs of farmers supplying ecosystem services. Although auctions are increasingly used for allocation in PES schemes, the factors that lead to their successful implementation and eventual environmental outcomes are poorly understood in developing countries. We investigated the socio-economic and institutional contexts that led to smallholders' auction winning and eventual compliance using linear mixed-effects models, and post-auction and post-contract surveys. We employed a case study of a conservation contract preceded by a sealed-bid, multiple round, uniform price auction for watershed services from coffee farmers in Lampung, Indonesia. The auction participants presented low education levels, low asset endowments and small plot sizes. The study obtained evidence that farmers with larger plot areas were more likely to win the contracts, suggesting economies of scale. Most farmers considered the auction a fair self-selection mechanism to allocate contracts where allocation was not influenced by power or social rank. Non-compliance was associated with labor availability constraints, short duration of land ownership and existence of previous conservation applications, suggesting lax of capability to invest in applying conservation agriculture. Final bids were however not good predictors of compliance, among other factors, calling into question the potential of auctions to elicit the actual incentive from the farmers. Ensuring that farmers understand the purposes of auctions for effective contract allocation beyond a mere game and identifying farmers that might encounter difficulties fulfilling the contract could increase the likelihood that such a PES scheme would be successful.     

Nowcasting and forecasting GDP in emerging markets using global financial and macroeconomic diffusion indexes

This paper contributes to the nascent literature on nowcasting and forecasting GDP in emerging market economies using big data methods. This is done by analyzing the usefulness of various dimension-reduction, machine learning and shrinkage methods, including sparse principal component analysis (SPCA), the elastic net, the least absolute shrinkage operator, and least angle regression when constructing predictions using latent global macroeconomic and financial factors (diffusion indexes) in a dynamic factor model (DFM). We also utilize a judgmental dimension-reduction method called the Bloomberg Relevance Index (BRI), which is an index that assigns a measure of importance to each variable in a dataset depending on the variable’s usage by market participants. Our empirical analysis shows that, when specified using dimension-reduction methods (particularly BRI and SPCA), DFMs yield superior predictions relative to both benchmark linear econometric models and simple DFMs. Moreover, global financial and macroeconomic (business cycle) diffusion indexes constructed using targeted predictors are found to be important in four of the five emerging market economies that we study (Brazil, Mexico, South Africa, and Turkey). These findings point to the importance of spillover effects across emerging market economies, and underscore the significance of characterizing such linkages parsimoniously when utilizing high-dimensional global datasets.     

Search efficiency,wage dynamics and welfare

Advances in information technology have improved the job-search process in the labor market. We analyze the effects of this improvement by constructing a search-and-matching model with two sectors: a risky sector with firm-specific productivity shocks and a risk-free sector. The risky sector is characterized by a low level of commitment between employers and workers – either party can end the employment relationship. We show that a better job-search process generates more job matches in the risky sector, and this benefits workers by improving their outside options. The effect on employers is subtle: while it is easier to fill vacancies, workers become more expensive. At the same time, the ease of finding new workers makes it harder for employers to keep their wage promises to workers and increases wage volatility. Our paper contributes to the literature by offering a novel explanation for the observed rise in wage volatility.     

不完备信息系统辐射源威胁等级判定

针对不完备信息系统条件下的辐射源威胁等级判定问题，提出了一种基于改进容差关系粗糙集（ITR-RS）的不完备信息系统辐射源威胁等级判定方法。该方法将粗糙集中的不完备信息系统理论引入辐射源威胁等级判定中，并构建一套完备的决策规则提取模型。此外，利用辨识矩阵实现对属性的约简，在降低系统所需处理数据量的同时，提高了算法的实时性；在容差关系粗糙集的基础上，提出一种改进的容差关系，在属性主、客权重相结合的基础上引入阈值来划分加权阈值容差类，得到更为合理、准确的决策规则。仿真试验及分析表明，与经典RS算法相比，所提算法的威胁等级判定正确率提高了23%，可用于信息系统不完备条件下的辐射源威胁等级判定。     

TEN YEARS OF GENERAL OLIGOPOLISTIC EQUILIBRIUM: A SURVEY

In this paper, I survey the recent and rapidly increasing theoretical literature using the brand‐new approach in embedding oligopolistic competition in general equilibrium, as designed by J. Peter Neary. First, I introduce the reader to Neary's approach, by describing the main ingredients. Then, I present a comprehensive set of studies that, over the last decade, apply this approach in different contexts, most of which are in open economy, and I examine the relevant outcomes. Although the theoretical literature has generously advanced, there is a lack of research on the empirical side, which would be an important area for future research besides theoretical extensions, some of which I highlight in the conclusions.     

Is the environment‐friendly factor attractive to customers when purchasing electric vehicles? Evidence from South Korea

In a bid to reduce greenhouse gas emissions, several countries worldwide are implementing policies to promote electric vehicles (EVs). However, contrary to expectations, the diffusion speed of EVs has been rather slow in South Korea. This study analyzes consumer preferences for the technological and environmental attributes of EVs and derives policy and environmental implications to promote market diffusion of EVs in South Korea. We conduct a choice‐based conjoint survey of 1,008 consumers in South Korea and estimate the consumer utility function using a mixed logit model considering consumer heterogeneity. Based on the consumer utility function, we analyze consumers' willingness‐to‐pay (WTP) for EV attributes such as driving range, charging method, charging time, autonomous driving function, carbon dioxide (CO₂) reduction rate, and purchase price. The results indicate that the current low acceptance of EVs is due to their relatively high price and lack of a battery charging technology that satisfies consumers' expectations of the charging method and time. One interesting finding is that Korean consumers have a relatively higher WTP for the CO₂ reduction rate of EVs than consumers in other countries; however, they do not consider CO₂ reduction over other technological attributes when choosing EVs. This implies that the rate of CO₂ reduction of EVs is not an important factor for South Korean consumers when buying EVs. We also calculate the effect of CO₂ reduction with the market penetration of EVs and find that CO₂ reduction through the diffusion of EVs depends on the country's electricity generation mix.     

Reducing High Public Debt Ratios: Lessons from UK Experience*

This paper examines contrasting experiences of the United Kingdom in addressing high public debt to GDP ratios following major wars. A clear message is that interest rate / growth rate differentials were more important than primary budget surpluses for the different outcomes. The debt to GDP ratio fell very rapidly under financial repression following the Second World War but remained stubbornly high despite large budget surpluses with price deflation after the First World War. Implications for policymakers today are that averting price deflation is a high priority and that supply‐side policies that raise growth could play an important part in debt reduction.     

城镇就业市场上劳动力工资扭曲程度测度

本文利用CHIPS2007数据库，基于随机前沿模型对我国城镇就业市场上劳动力的工资扭曲程度进行测度。研究结果表明：（1）在城镇就业市场上，由于工资扭曲现象的存在，劳动力实际获得的工资要比他们的边际生产率低45％～60％；（2）已婚、子女个数较少、本地、拥有失业保险、男性、大中型企业的劳动力工资扭曲程度要低于未婚、子女个数较多、外来、没有失业保险、女性、小型企业的劳动力；（3）中低工资水平的劳动力工资扭曲程度要比高工资水平的劳动力严重，且中低工资水平劳动力工资扭曲程度的方差更大。由此，本文提出推进就业市场的市场化改革，完善就业市场信息网络，从而减轻劳动力工资扭曲程度。