The spread of invasive species (IS) has the potential to upset ecosystem balances. In extreme cases, this can hinder economical utilization of both aquatic (fisheries) and terrestrial (agricultural) systems. As a result, many countries regard risk assessment of IS as an important process for solving the problem of biological invasion. Yet, some IS are purposefully introduced for what is seen as their potential economic benefits. Thus, conducting IS risk assessments and then formulating policies based on scientific information will allow protocols to be developed that can reduce problems associated with IS incursions, whether occurring purposefully or not. However, the risk assessment methods currently adopted by most countries use qualitative or semiquantitative methodologies. Currently, there is a mismatch between qualitative and quantitative assessments. Moreover, most assessment systems are for terrestrial animals. What is needed is an assessment system for aquatic animals; however, those currently available are relatively rudimentary. To fill this gap, we used the analytic hierarchy process (AHP) to build a risk assessment model system for aquatic IS. Our AHP has four primary indexes, twelve secondary indexes, and sixty tertiary indexes. We used this AHP to conduct quantitative risk assessments on five aquatic animals that are typically introduced in China, which have distinct biological characteristics, specific introduction purposes, and can represent different types of aquatic animals. The assessment results show that the risk grade for Pterygoplichthys pardalis is high; the risk grade for Macrobrachium rosenbergii, Crassostrea gigas, and Trachemys scripta elegans is medium; and the grade risk for Ambystoma mexicanum is low. Risk assessment of the introduction of aquatic animals using our AHP is effective, and it provides support for the introduction and healthy breeding of aquatic animals. Thus, the AHP model can provide a basis for decision-making risk management concerning the introduction of species.

Taking the double-layer water injection well and one graded water distributor could regulate two layers as the design and research goal, the sliding double-layer water injection distributor was designed by using the forward and reverse rotation of the driving motor to control the opening and closing of the two nozzles. The flow field of the two flow channels under different opening was analyzed by FLUENT software. The research shows that when the opening of the nozzle was less than 10mm, the maximum flow rate decreases rapidly, and when the opening exceeds 10mm, it decreases slowly. The mathematical models of flow pressure, flow velocity, and nozzle opening were obtained by data analysis and fitting. Finally, the kinematics simulation was carried out by AAMS, and the maximum friction force borne by each sealing in the movement process was obtained. The maximum torque borne in the movement process was 120.5N·m, which was less than the rated torque. The supporting motor could meet the design requirements.