Suchergebnisse

Exploring virtual land trade (VLT) embodied in the global agricultural trade enables us to uncover potential risks to economy, environment, and food security within the trade structure. Using the bilateral trade data for the periods of 1988–1990, 1998–2000, 2008–2010, and 2018–2020, we created halfcircle diagrams depicting how virtual land of cereals is traded between countries of different income levels. The diagrams show that the global trend of virtual land in cereal products was being exported from high-income to low-income countries. Initially, a few wealthy countries dominated exports, and in later periods, middle-income countries joined major exporters. There has been a significant increase in the number of countries participating in VLT. Halfcircle diagrams are a useful tool for visualizing overall trends of VLT in relation to a potential driver.

Multiobjective site-search problems are a class of decision problems that have geographical components and multiple, often conflicting, objectives; this kind of problem is often encountered and is technically difficult to solve. In this paper we describe an evolutionary algorithm (EA) based approach that can be used to address such problems. We first describe the general design of EAs that can be used to generate alternatives that are optimal or close to optimal with respect to multiple criteria. Then we define the problem addressed in this research and discuss how the EA was designed to solve it. In this procedure, called MOEA/Site, a solution (that is, a site) is encoded by using a graph representation that is operated on by a set of specifically designed evolutionary operations. This approach is applied to five different types of cost surfaces and the results are compared with 10 000 randomly generated solutions. The results demonstrate the robustness and effectiveness of this EA-based approach to geographical analysis and multiobjective decisionmaking. Critical issues regarding the representation of spatial solutions and associated evolutionary operations are also discussed.