A Reverse Order Hierarchical Integrated Scheduling Algorithm Considering Dynamic Time Urgency Degree of the Process Sequences

Aiming at the general integrated scheduling problem of tree-structured complex single-product machining and assembling, a reverse order hierarchical integrated scheduling algorithm (ROHISA) is proposed by considering the dynamic time urgency degree (TUD) of process sequences (PSs). The strategy of process sorting is put forward, and the TUD of PS is defined. The process tree is reversed using leaf alignment, and according to the order from leaf to root, the scheduling order of leaf nodes in the same layer is determined layer by layer according to the TUD values of the PSs to which the leaf nodes belong. In turn, the sorted leaf nodes in each layer are stored in a corresponding layered array (LA). Finally, the elements in each LA are reversed, and the LAs’ arranging order is reversed. A reverse order hierarchical scheduling strategy is proposed. Starting from the root node, every LA is taken as a unit to conduct trial scheduling each time. Under the condition of meeting the craft constraints, a set of quasi-scheduling schemes of same-layer processes (QSSSLP) is obtained, and the one with the minimum end time is selected from it as the scheduling scheme of the same layer processes (SSSLP). If it is not unique, the QSSSLP that machines all the same layer processes (SLP) as early as possible is selected. The research shows that the ROHISA optimizes the integrated scheduling results of single-product manufacturing enterprises and improves its production efficiency

A Reverse Order Hierarchical Integrated Scheduling Algorithm Considering Dynamic Time Urgency Degree of the Process Sequences

Aiming at the general integrated scheduling problem of tree-structured complex single-product machining and assembling, a reverse order hierarchical integrated scheduling algorithm (ROHISA) is proposed by considering the dynamic time urgency degree (TUD) of process sequences (PSs). The strategy of process sorting is put forward, and the TUD of PS is defined. The process tree is reversed using leaf alignment, and according to the order from leaf to root, the scheduling order of leaf nodes in the same layer is determined layer by layer according to the TUD values of the PSs to which the leaf nodes belong. In turn, the sorted leaf nodes in each layer are stored in a corresponding layered array (LA). Finally, the elements in each LA are reversed, and the LAs’ arranging order is reversed. A reverse order hierarchical scheduling strategy is proposed. Starting from the root node, every LA is taken as a unit to conduct trial scheduling each time. Under the condition of meeting the craft constraints, a set of quasi-scheduling schemes of same-layer processes (QSSSLP) is obtained, and the one with the minimum end time is selected from it as the scheduling scheme of the same layer processes (SSSLP). If it is not unique, the QSSSLP that machines all the same layer processes (SLP) as early as possible is selected. The research shows that the ROHISA optimizes the integrated scheduling results of single-product manufacturing enterprises and improves its production efficiency

Symmetric Two-Workshop Heuristic Integrated Scheduling Algorithm Based on Process Tree Cyclic Decomposition

The existing research on the two-workshop integrated scheduling problem with symmetrical resources does not consider the complex product attribute structure and the objective situation of plant equipment resources. This results in the prolongation of the product makespan and the reduction of the utilization rate of the general equipment in the workshop. To solve the above problems, a two-workshop integrated scheduling algorithm based on process tree cyclic decomposition (STHIS-PTCD) was proposed. First, a workshop scheduling scheme based on the sub-tree cyclic decomposition strategy was proposed to improve the closeness of continuous processing further. Second, an operation allocation scheme based on the principle of workshop processing balance was presented. On the basis of ensuring the advantages of parallel processing, it also effectively reduces the idle time of equipment resources and then optimizes the overall effect of the integrated scheduling of both workshops. Through the comparison and analysis of all the existing resource-symmetric two-workshop integrated scheduling algorithms, the scheduling effect of the proposed algorithm is the best

Low-Temperature Methane Combustion over Pd/H-ZSM-5: Active Pd Sites with Specific Electronic Properties Modulated by Acidic Sites of H‑ZSM‑5

Pd/H-ZSM-5 catalysts could completely catalyze CH₄ to CO₂ at as low as 320 °C, while there is no detectable catalytic activity for pure H-ZSM-5 at 320 °C and only a conversion of 40% could be obtained at 500 °C over pure H-ZSM-5. Both the theoretical and experimental results prove that surface acidic sites could facilitate the formation of active metal species as the anchoring sites, which could further modify the electronic and coordination structure of metal species. PdO_<i>x</i> interacting with the surface Brönsted acid sites of H-ZSM-5 could exhibit Lewis acidity and lower oxidation states, as proven by the XPS, XPS valence band, CO-DRIFTS, pyridine FT-IR, and NH₃-TPD data. Density functional theory calculations suggest PdO_<i>x</i> groups to be the active sites for methane combustion, in the form of [AlO₂]­Pd­(OH)-ZSM-5. The stronger Lewis acidity of coordinatively unsaturated Pd and the stronger basicity of oxygen from anchored PdO_<i>x</i> species are two key characteristics of the active sites ([AlO₂]­Pd­(OH)-ZSM-5) for methane combustion. As a result, the PdO_<i>x</i> species anchored by Brønsted acid sites of H-ZSM-5 exhibit high performance for catalytic combustion of CH₄ over Pd/H-ZSM-5 catalysts

The First Crested Duck Genome Reveals Clues to Genetic Compensation and Crest Cushion Formation

The Chinese crested (CC) duck is a unique indigenous waterfowl breed, which has a crest cushion that affects its survival rate. Therefore, the CC duck is an ideal model to investigate the genetic compensation response to maintain genetic stability. In the present study, we first generated a chromosome-level genome of CC ducks. Comparative genomics revealed that genes related to tissue repair, immune function, and tumors were under strong positive selection, indicating that these adaptive changes might enhance cancer resistance and immune response to maintain the genetic stability of CC ducks. We also assembled a Chinese spot-billed (Csp-b) duck genome, and detected the structural variations (SVs) in the genome assemblies of three ducks (i.e., CC duck, Csp-b duck, and Peking duck). Functional analysis revealed that several SVs were related to the immune system of CC ducks, further strongly suggesting that genetic compensation in the anti-tumor and immune systems supports the survival of CC ducks. Moreover, we confirmed that the CC duck originated from the mallard ducks. Finally, we revealed the physiological and genetic basis of crest traits and identified a causative mutation in TAS2R40 that leads to crest formation. Overall, the findings of this study provide new insights into the role of genetic compensation in adaptive evolution