Accelerate Solving Expensive Scheduling by Leveraging Economical Auxiliary Tasks

To fully leverage the multi-task optimization paradigm for accelerating the solution of expensive scheduling problems, this study has effectively tackled three vital concerns. The primary issue is identifying auxiliary tasks that closely resemble the original expensive task. We suggested a sampling strategy based on job importance, creating a compact matrix by extracting crucial rows from the entire problem specification matrix of the expensive task. This matrix serves as an economical auxiliary task. Mathematically, we proved that this economical auxiliary task bears similarity to its corresponding expensive task. The subsequent concern revolves around making auxiliary tasks more cost-effective. We determined the sampling proportions for the entire problem specification matrix through factorial design experiments, resulting in a more compact auxiliary task. With a reduced search space and shorter function evaluation time, it can rapidly furnish high-quality transferable information for the primary task. The last aspect involves designing transferable deep information from auxiliary tasks. We regarded the job priorities in the (sub-) optimal solutions to the economical auxiliary task as transferable invariants. By adopting a partial solution patching strategy, we augmented specificity knowledge onto the common knowledge to adapt to the target expensive task. The strategies devised for constructing task pairs and facilitating knowledge transfer, when incorporated into various evolutionary multitasking algorithms, were utilized to address expensive instances of permutation flow shop scheduling. Extensive experiments and statistical comparisons have validated that, with the collaborative synergy of these strategies, the performance of evolutionary multitasking algorithms is significantly enhanced in handling expensive scheduling tasks

Resonance Control Based on Hydrodynamic Analysis for Underwater Direct Drive Wave Energy Converter

Wave energy has great prospect among many forms of marine renewable energy for its high density and storage. This paper proposes an underwater direct drive wave energy converter (UDDWEC), which is composed of a submerged point absorbing buoy and a linear-rotating axial flux permanent magnetic generator (LR-AFPMG). In addition, a maximum energy capture control strategy, resonance control, is derived for UDDWEC, based on small amplitude oscillation and hydrodynamic analysis. The proposed control strategy assumes the availability of sea condition such as wave height and period. This control strategy has three main characteristics. Firstly, this control strategy is derived based on hydrodynamic analysis of the submerged point absorber. Added mass, radiation damping and other hydrodynamic parameters are obtained to participate in UDDWEC dynamic model. Secondly, a LR-AFPMG is applied as power take-off device to realize energy conversion, which can improve the power density. Thirdly, small amplitude oscillation can be changed into long stroke rotary motion through the LR-AFPMG. The reliability and effectiveness of the proposed control strategy are assessed at various operation conditions for a heaving system and the validity for the UDDWEC is verified

Response of soil microbial communities to continuously mono-cropped cucumber under greenhouse conditions in a calcareous soil of north China

Purpose: Microbes are the engines for nutrient cycling in the soil, playing an important role in maintaining soil quality and agricultural production, but it is unclear how soil microbial communities respond to continuously mono-cropped cucumber under greenhouse conditions. Materials and methods: High-throughput sequencing of the bacterial 16S rRNA and fungal 18S rRNA gene fragments was conducted to compare the variations of microbial communities within greenhouse mono-cropped cucumber systems across 8, 15, and 22 cultivation years with new-build greenhouse of cucumber cultivated just for one season (1 year). Results and discussion: Results showed that soil pH and fungal diversity significantly decreased, whereas soil EC, organic matter (OM), and nutrient concentrations (total nitrogen (N), nitrate N (NO₃⁻-N), total and available phosphorus, and potassium) significantly increased when cucumber was mono-cropped for 8 or more years. The mono-cropped cucumber for 8 or more years reduced the relative abundance of the dominant bacterial phyla Actinobacteria, but increased the abundances of Acidobacteria and Firmicutes significantly compared with the cucumber planted for one season. Moreover, the predominant fungal phylum Ascomycota increased significantly with increasing cultivation years of cucumber. Soil OM and NO₃⁻-N are most important factors to drive the variation of soil bacterial community, while soil pH, OM, and NO₃⁻-N markedly responded to the changes of the fungal community in the greenhouse cucumber mono-cropped system. Conclusions: This research provides insights into the response of microbial communities to continuous mono-cropping cucumber, and this has implications on the sustainability of such intensive production system