Hub location problems in transportation networks

In this paper we propose a 4-index formulation for the uncapacitated multiple allocation hub location problem tailored for urban transport and liner shipping network design. This formulation is very tight and most of the tractable instances for MIP solvers are optimally solvable at the root node. While the existing state-of-the-art MIP solvers fail to solve even small size instances of problem, our accelerated and efficient primal (Benders) decomposition solves larger ones. In addition, a very efficient greedy heuristic, proven to be capable of obtaining high quality solutions, is proposed. We also introduce fixed cost values for Australian Post (AP) dataset.     

物联网环境下基于智能代理的建材交易平台研究

通过物联网环境下的基于智能代理的建材交易平台,建立起“人”与“物”之间的应用,将各建材企业的自动化立体仓库作为物流基础设施,利用自动化立体仓库的数据库系统构建Web站点,为建材交易平台提供基础数据支持,并以比较搜索引擎为核心,通过各智能代理模块的交互实现该平台的各项功能.     

对远期外汇合约信用风险的监管

随着远期外汇合约近几年来在我国的逐步推行,外汇市场活跃的同时也增加了外汇交易的信用风险,。要实现外汇市场的有序开放和稳定发展,就必须对其实行有效的风险管理,这包括交易主体对信用风险的识别,处置和外部监管。     

Exploring the relationships between knowledge sources in the innovation process: evidence from Finnish innovators

Innovation is a costly, risky, and uncertain process, and one of its most central components is knowledge as has been emphasised in the innovation literature. Notably, such knowledge tends to be distributed across different internal and external sources. That is, innovation processes involve diverse relationships between knowledge that originates from a myriad of different sources such as customers, suppliers and universities. While such relationships are distinctive to modern – distributed – innovation processes, little is still known about their implications on the search for new knowledge. This paper proposes that since the innovation process is inherently an uncertain and costly activity, a deeper understanding on the relationships between knowledge sources can help firms to better master the risks and costs related to their search activities. In other words, given that not all knowledge is equally combinable with each other, it claims that complementarities among knowledge sources increase the likelihood (over non-complementarities and substitutes) that such sources encompass mutually combinable knowledge, and hence decrease the uncertainties, risks and costs involved in distributed innovation processes.     

Emerging search regimes: measuring co-evolutions among research,science, and society

Scientometric data is used to investigate empirically the emergence of search regimes in biotechnology, genomics and nanotechnology. Complex regimes can emerge when three independent sources of variance interact. In our model, researchers can be considered as the nodes that carry the science system. Research is geographically situated with site-specific skills, tacit knowledge and infrastructures. Second, the emergent science level refers to the formal communication of codified knowledge published in journals. Third, the socio-economic dynamics indicate the ways in which knowledge production relates to society. Although biotechnology, genomics and nanotechnology can all be characterised by rapid growth and divergent dynamics, the regimes differ in terms of self-organisation among these three sources of variance. The scope of opportunities for researchers to contribute within the constraints of the existing body of knowledge are different in each field. Furthermore, the relevance of the context of application contributes to the knowledge dynamics to various degrees.     

Learning to choose a commodity-money: Carl Menger's theory of imitation and the search monetary framework

This paper studies Carl Menger's theory of the emergence of a commodity money. We propose an interpretation of Menger's learning by imitation process based on the search theoretical formal framework. We show that there exists a tension between the importance of intrinsic properties of commodities and the pure conventional self-fulfilling expectations of agents. This confirms the role of imitation in the emergence of monetary equilibria in search theory. We conclude that Menger's approach may support the idea that the fundamental property of a commodity-money (namely its great liquidity) is the result of its emergence process and not necessarily of its original intrinsic properties.     

Flexibility at the Margin and Labor Market Volatility in OECD Countries*

We study the business‐cycle behavior of segmented labor markets with flexibility at the margin (e.g., just affecting fixed‐term contracts). We present a matching model with temporary and permanent jobs (i) where there is a gap in the firing costs associated with these types of jobs and (ii) where there are restrictions in the creation and duration of fixed‐term contracts. We show that a labor market with ``flexibility at the margin'' increases the unemployment volatility with respect to one that is fully regulated. This analysis yields new insights into the interpretation of the recent volatility changes witnessed in the OECD area.     

从百度文库搜索引擎侵权事件引发的法律思考——兼论网络侵权的规制

针对百度文库侵权案例的辨析,本文对百度搜索引擎ISP在实质性非侵权用途、共同侵权、避风港原则等方面进行认定。从而提出对我国在网络侵权方面应加强完善间接侵权规则、界定网络服务主体的性质、适当加大网络服务提供商的责任以及制定《网络侵权责任法》的规制建议。通过本文的研究,寻求搜索引擎行为在法律规制过程中所追求的价值目标。     

Informality,public employment and employment protection in developing countries

This paper proposes an equilibrium matching model for developing countries’ labor markets where the interaction between public, formal private and informal private sectors are taken into account. Theoretical analysis shows that gains from reforms aiming at liberalizing formal labor markets can be annulled by shifts in the public sector employment and wage policies. Since the public sector accounts for a substantial share of employment in developing countries, this approach is crucial to understand the main labor market outcomes of such economies. Wages offered by the public sector increase the outside option value of the workers during the bargaining processes in the formal and informal sectors. It becomes more profitable for workers to search on-the-job, in order to move to these more attractive and more stable types of jobs. The public sector therefore acts as an additional tax for the formal private firms. Using data on workers’ flows from Egypt, we show empirically and theoretically that the liberalization of labor markets plays against informal employment by increasing the profitability, and hence job creations, of formal jobs. The latter effect is however dampened or even sometimes nullified by the increase of the offered wages in the public sector observed at the same time.     

Sibling gender and wage differences

Family influences on economic performance are investigated. In particular, sibship sex composition is related to hourly wages using data from the National Longitudinal Survey of Youth 1979. The wages of men are increasing in the proportion of siblings who are brothers, but the wages of women are insensitive to sibling gender. Nonwage outcomes are generally unaffected. Contrasts by age structure and demographic group are also presented. The analysis addresses econometric challenges like the endogeneity of fertility and selection into the workforce. In addition, mechanisms such as labour market interactions, human capital investment and role model effects are documented. A questionnaire on job search indicates a same-gender bias in the use of brothers and sisters in obtaining employment. Developmental and psychological assessments suggest that brothers may be associated with worse childhood home environments and more traditional family attitudes among women. The findings are policy relevant and contribute to an understanding of gender differences and earnings inequality.