标题： 贸易流网络的层次性揭示了产品的复杂性 显示英文标题

标题： Hierarchicality of Trade Flow Networks Reveals Complexity of Products

摘要： 随着全球化，国家之间通过贸易流量的联系比以前更加紧密，目前贸易流量至少达到36万亿美元。 有趣的是，大约30-60%的全球出口由中间产品组成。 因此，具有高附加值的特定产品的贸易流量网络可以被视为价值链。 问题是，我们能否根据其独特的流量网络结构来区分这些产品。 本文将生态学中开发的流量分析方法应用于638个不同产品的贸易流量网络。 我们认为，异速生长指数$\eta$可以用来表征流量网络的层级程度，即贸易产品是否在长的层级链上流动。 然后，具有更高附加值和复杂性的产品的流量网络，如具有较大指数的机械和运输设备，被突出显示。 这些较高的数值表明它们的贸易流量网络更具层级性。 因此，无需额外的数据，如全球投入产出表，我们仅通过贸易网络就可以识别出具有更高复杂性的产品类别以及一个国家在全球价值链中的相对重要性。 显示英文摘要

摘要： With globalization, countries are more connected than before by trading flows, which currently amount to at least 36 trillion dollars. Interestingly, approximately 30-60 percent of global exports consist of intermediate products. Therefore, the trade flow network of a particular product with high added values can be regarded as a value chain. The problem is weather we can discriminate between these products based on their unique flow network structure. This paper applies the flow analysis method developed in ecology to 638 trading flow networks of different products. We claim that the allometric scaling exponent $\eta$ can be used to characterize the degree of hierarchicality of a flow network, i.e., whether the trading products flow on long hierarchical chains. Then, the flow networks of products with higher added values and complexity, such as machinery&transport equipment with larger exponents, are highlighted. These higher values indicate that their trade flow networks are more hierarchical. As a result, without extra data such as global input-output table, we can identify the product categories with higher complexity and the relative importance of a country in the global value chain solely by the trading network.