Focusing on the multi-depot vehicle routing problem (MDVRP) for hazardous materials transportation, this paper presents a multi-objective optimization model to minimize total transportation energy consumption and transportation risk. A two-stage method (TSM) and hybrid multi-objective genetic algorithm (HMOGA) are then developed to solve the model. The TSM is used to find the set of customer points served by each depot through the global search clustering method considering transportation energy consumption, transportation risk, and depot capacity in the first stage, and to determine the service order of customer points to each depot by using a multi-objective genetic algorithm with the banker method to seek dominant individuals and gather distance to keep evolving the population distribution in the second stage, while with the HMOGA, customer points serviced by the depot and the serviced orders are optimized simultaneously. Finally, by experimenting on two cases with three depots and 20 customer points, the results show that both methods can obtain a Pareto solution set, and the hybrid multi-objective genetic algorithm is able to find better vehicle routes in the whole transportation network. Compared with distance as the optimization objective, when energy consumption is the optimization objective, although distance is slightly increased, the number of vehicles and energy consumption are effectively reduced.
The diverse habitat of the coastal areas of Guangdong, China, supports important waterbird populations, thereby contributing to the conservation of waterbirds in China and globally. The sensitivity of different waterbirds to environmental driving factors results in differences in habitat selection, which in combination affect waterbird abundance. This study investigated the effects of environmental and human disturbance factors on the abundance of waterbirds based on a survey of waterbirds in coastal areas of Guangdong Province, China. Redundancy analysis (RDA) was mainly used to study the relationships between the abundance of waterbirds and environmental and human factors. The results showed that the areas of mangrove and tidal flats were the main factors driving the abundance of shorebirds and open water waterbirds, whereas the areas of mangrove and water bodies were the main factors driving the abundance of wading birds and waterfowl, respectively. Road length and the areas of construction land were found to have negative effects on the abundance of waterbirds. A waterbird protection and management strategy was proposed based on the results.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.