Model and heuristic solutions for the multiple double-load crane scheduling problem in slab yards

This article studies a multiple double-load crane scheduling problem in steel slab yards. Consideration of multiple cranes and their double-load capability makes the scheduling problem more complex. This problem has not been studied previously. We first formulate the problem as a mixed-integer linear programming (MILP) model. A two-phase model-based heuristic is then proposed. To solve large problems, a pointer-based discrete differential evolution (PDDE) algorithm was developed with a dynamic programming (DP) algorithm embedded to solve the one-crane subproblem for a fixed sequence of tasks. Instances of real problems are collected from a steel company to test the performance of the solution methods. The experiment results show that the model can solve small problems optimally, and the solution greatly improves the schedule currently used in practice. The two-phase heuristic generates near-optimal solutions, but it can still only solve comparatively modest problems within reasonable (4 h) computational timeframes. The PDDE algorithm can solve large practical problems relatively quickly and provides better results than the two-phase heuristic solution, demonstrating its effectiveness and efficiency and therefore its suitability for practical use

Palladium-Catalyzed β‑Arylation of Amide via Primary sp³C–H Activation

A β-arylation of primary sp³C–H bonds on simple amides such as pivalamides with aryl iodides/CF₃CO₂Ag has been established successfully at 120 °C in a Pd­(OAc)₂ (catalyst)/CF₃CH₂OH (solvent) system. Pivalamides including ^<i>t</i>BuCONH₂, ^<i>t</i>BuCONHR, and ^<i>t</i>BuCONR₂ undergo the arylations smoothly to afford β-aryl pivalamides in moderate to good yields. Various aryl iodides are available bearing either electron-donating or electron-withdrawing substituted groups in the coupling reactions

Palladium-Catalyzed β‑Mesylation of Simple Amide via Primary sp³ C–H Activation

A β-mesylation of primary sp³ C–H bonds from simple amides with methanesulfonic anhydride (Ms₂O) has been established successfully at 80 °C in a Pd­(OAc)₂ (catalyst)/K₂S₂O₈ (oxidant)/CF₃CH₂OH (solvent) system. These amide substrates involve <i>N</i>-monosubstituted linear, branch, or cyclic alkanes, and electron-deficient benzyl compounds. The β-mesylated amide products can be converted easily to β-fluoroamides or β-lactams through inter- or intramolecular S_N2 processes

Logistics optimisation of slab pre-marshalling problem in steel industry

© 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group. We study the slab pre-marshalling problem to re-position slabs in a way that the slabs are stored in the least number of stacks and each stack contains only the slabs of the same group, which can be utilised interchangeably. In this way, when a slab of any group is required, the topmost slab can always be picked up without shuffling. During pre-marshalling, however, at most two slabs can be moved by one operation. In this paper, we present a network model with three valid inequalities to solve this problem. With a small amount of labelled data from the model approach, a self-training technique is applied to train a function for predicting the best next move. Then, a new hybrid algorithm is developed to solve the practical problems by combining the self-training technique, heuristics, and the branch-and-bound algorithm with five dominance rules. The experimental results demonstrate the effectiveness of this network model and valid inequalities, and the performances of different components of this algorithm. The new algorithm produces high-quality solutions within seconds

Additional file 1: Table S1. of The impact of resilience on psychological outcomes in women with threatened premature labor and spouses: a cross-sectional study in Southwest China

Socio-demographic data between women with TPL and spouses divided by level of resilience of women. Table S2 Psychometric data between women with TPL and spouses divided by level of resilience of women. Table S3 Correlations between psychological factors of women with TPL and spouses. (DOCX 20 kb