2 research outputs found
A new knowledge-guided multi-objective optimisation for the multi-AGV dispatching problem in dynamic production environments
The efficiency of material supply for workstations using Automatic Guided Vehicles (AGVs) is largely determined by the performance of the AGV dispatching scheme. This paper proposes a new solution approach for the AGV dispatching problem (AGVDP) for material replenishment in a general manufacturing workshop where workstations are in a matrix layout, and where uncertainty in replenishment time of workstations and stochastic unloading efficiencies of AGVs are dynamic contextual factors. We first extend the literature proposing a mixed integer optimisation model with a delivery satisfaction soft constraint of material orders and two objectives: transportation costs and delivery time deviation. We then develop a new knowledge-guided estimation of distribution algorithm with delivery satisfaction evaluation for solving the model. Our algorithm fuses three knowledge-guided strategies to enhance optimisation capabilities at its respective execution stages. Comprehensive numerical experiments with instances built from a real-world scenario validate the proposed model and algorithm. Results demonstrate that the new algorithm outperforms three popular multi-objective evolutionary algorithms, a discrete version of a recent multi-objective particle swarm optimisation, and a multi-objective estimation of distribution algorithm. Findings of this work provide major implications for workshop management and algorithm design.</p
Formation of Anisotropic Liquid Crystalline Nanoparticles via Polymerization-Induced Hierarchical Self-Assembly
Polymeric
nanoparticles (NPs) containing liquid crystalline (LC)
mesogens with tunable anisotropic morphologies have applications in
various fields, but their preparation typically suffers from tedious
and low-throughput approaches. Here we present an efficient route
to the preparation of anisotropic morphologies of azobenzene-containing
block copolymers (BCPs) at high solids content via a polymerization-induced
hierarchical self-assembly in ethanol. Various anisotropic NPs, including
cuboids, short belts, lamellae, and ellipsoidal vesicles, have been
obtained in a remarkably broad range of BCP compositions. The NPs
exhibit a smectic phase with ordered stripes when observed under TEM.
This internal LC ordering plays a significant role on the formation
of these intriguing anisotropic morphologies. Morphological transitions
from anisotropic to isotropic spheres can be obtained upon UV illumination
due to the photoresponsive properties of the azobenzene mesogens.
This work significantly expands the scope of accessible morphologies
in PISA and suggests that the under explored LC BCPs may have an impactful
role in the PISA field