Computing equilibria of GEI by relocalization on a Grassmann manifold

An algorithm is described to compute equilibria of the general economic model with incomplete asset markets, that is, of GEI. The algorithm is based on the existence of a route of zeros of a homotopy whose domain includes the price simplex and a Grassmann Manifold. This route is followed, in effect, by localizing and following diffeomorphic pieces in Euclidean space, and by relocalizing as is necessary.     

On the multi-dimensionality and sampling of air transport networks

Complex network theory is a framework increasingly used in the study of air transport networks, thanks to its ability to describe the structures created by networks of flights, and their influence in dynamical processes such as delay propagation. While many works consider only a fraction of the network, created by major airports or airlines, for example, it is not clear if and how such sampling process bias the observed structures and processes. In this contribution, we tackle this problem by studying how some observed topological metrics depend on the way the network is reconstructed, i.e. on the rules used to sample nodes and connections. Both structural and simple dynamical properties are considered, for eight major air networks and different source datasets. Results indicate that using a subset of airports strongly distorts our perception of the network, even when just small ones are discarded; at the same time, considering a subset of airlines yields a better and more stable representation. This allows us to provide some general guidelines on the way airports and connections should be sampled.     

Co‐movements in commodity prices: a note based on network analysis

This article analyses co‐movements in a wide group of commodity prices during the time period 1992–2010. Our methodological approach is based on the correlation matrix and the networks inside. Through this approach we are able to summarize global interaction and interdependence, capturing the existing heterogeneity in the degrees of synchronization between commodity prices. Our results produce two main findings: (a) we do not observe a persistent increase in the degree of co‐movement of the commodity prices in our time sample, however from mid‐2008 to the end of 2009 co‐movements almost doubled when compared with the average correlation; (b) we observe three groups of commodities which have exhibited similar price dynamics (metals, oil and grains, and oilseeds) and which have increased their degree of co‐movement during the sampled period.     

均匀圆阵的测向模糊研究

在高分辨阵列测向系统中,均匀圆阵(UCA)是一种广泛使用的阵列结构。利用均匀圆阵的阵列流形的微分几何作为分析工具,对实际中常用的几种均匀圆阵的测向模糊进行了大量的计算机仿真试验,定量地给出了这些阵列的测向模糊方向和相应的秩,揭示了均匀圆阵的测向模糊性能与其阵元数和孔径之间的关系,得出了一些有实际意义的结论。这对工程应用时均匀圆阵的选择和构造具有很强的参考价值和指导意义,可以避免系统设计的盲目性和随意性。     

浅析天然气汇管开裂原因与预防

通过对天然气汇管截面应力场的探讨,分析了汇管表面裂纹产生的原因并提出了相应预防措施。得出长庆油田第一采气厂出现表面裂纹的7台管汇是由于焊接和热处理工艺不当使残余应力过大所致。     

Synchronization and diversity in business cycles: a network analysis of the European Union

In this article, we use a correlation matrix and its internal networks to analyse business cycle synchronization across Europe since 2000. This methodology allows us to summarize individual country interactions and co-movements while also capturing the existing heterogeneity of connectivity within the European economic system. Our results indicate that synchronization of the euro zone countries remained stable from 1999 until the current financial crisis, after which co-movements increased sharply and synchronization rose to the highest in the time sample. By endogenously identifying clusters of countries with close connections in their business cycle, we also refute the commonly accepted notion of identifiable core and peripheral euro zone countries.     

基于复杂网络理论的电动汽车充电设施布局合理性研究

提出了一种基于复杂网络理论构建电动汽车充电设施网络的模型,分别构建了上海、西安、合肥和大连的电动汽车充电设施网络,并分析了其电动汽车充电设施的运营情况以及布局的合理性。通过构建理想情况下的电动汽车充电设施网络,研究电动汽车充电设施网络的发展趋势。仿真结果显示:电动汽车充电设施网络的结构对电动汽车充电设施的利用率和稳定性有显著影响——该研究结果在实际网络中得到了验证。     

The Urban Unbound: London's Politics and the 2012 Olympic Games

Global events such as London's 2012 Olympic Games raise questions about the ways in which embedded political arrangements take their shape from relationships that stretch across and beyond urban boundaries. In this article, the urban politics that we wish to capture is not one that is merely located in the city, but rather one that has to constantly take into account the mediated demands folded (as it were) into the urban arena. In the first part of the article, the corporate politics of an Olympic‐related urban regeneration are outlined and then considered, first as a staged setting for interaction, a kind of placeless political engagement, and then as a more embedded spatial politics that takes into account the leverage of networked groups acting within and beyond the city. Following that, we explore the politics of regeneration when campaign groups and alternative coalitions of interest raise their own political demands by drawing on references outside of their immediate urban area and attempt to steer political dialogue in ways that extend the reach of urban politics. The urban politics at stake in this context, we argue, appears to work more through topology than a series of mapped connections; through actors registering their presence in ways that often dissolve the tension between inside and outside rather than define it in terms of separate political spaces.