Chen Lan

Small and medium-sized enterprises are the main force of the industry, and higher vocational colleges are the main suppliers of talents for small and medium-sized enterprises. The two are highly complementary. From the perspective of innovation ecosystem, both are important populations in the system. Based on system dynamics, this paper constructs the collaborative innovation system model of small and medium-sized enterprises and higher vocational colleges, and focuses on the simulation of the operation mechanism of the innovation system. The research shows that the distribution of achievements has a significant impact on the operation of the system.

The aquatic environments of the world are facing the severe challenge of eutrophication. Lakes and reservoirs that are regarded as drinking water sources are particularly in danger. Once the water quality deteriorates, serious impacts will occur on the subsequent water supply and drinking water safety. This study focuses on the Aha Reservoir, a sub-deep eutrophic reservoir in Southwest China polluted by phosphorus. This site was selected because it is currently undergoing aquatic restoration. It will be the first to use bubble plume diffusers at the drinking water outlet area where water is removed from the reservoir to provide drinking water to the community, to enhance water quality. There was a significant decrease in total phosphorus (TP) and total nitrogen (TN) concentrations in the experimental zone (0.04-0.02 mg/L and 1.9-1.7 mg/L, respectively), with no significant decrease in TP and TN concentrations at the control sites. Compared with the control sites, concentrations of NH₄⁺, total Fe, and total Mn were reduced by 15.5%, 45.5%, and 48.9%, respectively. In addition, the application of this technique had a significant influence on the evolution of algal phytoplankton in the eutrophic reservoir. The number of cyanobacteria species in the drinking water outlet area decreased by 33-100% during the peak period of algal blooms, with no sign of an increase at all. Moreover, the number of phytoplankton species at the experimental site decreased by as much as 82.6% compared with the corresponding period prior to application. Hypolimnetic oxygenation displayed great effectiveness for aquatic restoration in this eutrophic water system.

Bubble plumes are a popular hypolimnetic reaeration technique in deep water reservoirs since they have the advantage of delivering direct reaeration to the hypolimnion. Improving the understanding of the integrated reaeration processes is beneficial to optimize the reaeration capacity of the aeration or oxygenation system. In this study, the discrete bubble model was first employed to design an oxygenation system for a sub-deep reservoir (the Aha Reservoir, southwest China, with water depth of 10–30 m). A new approach involving the discrete bubble model was used to determine the initial bubble size of the bubble plume application. The intrusion models were demonstrated to be useful for designing the gas flow rate of the reaeration system. Using the intrusion models, we predicted the intrusion thickness and intrusion distance during operation for the first time. Subsequently, we verified the predictions and produced more realistic empirical formulas. At present, reports about recommendations on initial bubble size and gas flow rate are rare, and practical verification is absent. Taking the Aha reservoir as an example, the initial bubble radius of 1 mm and the gas flow rate of 20 m³·h⁻¹ were recommended in the bubble plume oxygenation and were found to be successful in the field. Our understanding of the reaeration processes during the operation of the bubble plume system is far from comprehensive, but this study serves to highlight the potential of the discrete bubble model and the intrusion models for designing the bubble plume system in an individual lake.