An analytical hierarchy process-based approach to solve the multi-objective multiple traveling salesman problem

We consider the problem of assigning a team of autonomous robots to target locations in the context of a disaster management scenario while optimizing several objectives. This problem can be cast as a multiple traveling salesman problem, where several robots must visit designated locations. This paper provides an analytical hierarchy process (AHP)-based approach to this problem, while minimizing three objectives: the total traveled distance, the maximum tour, and the deviation rate. The AHP-based approach involves three phases. In the first phase, we use the AHP process to define a specific weight for each objective. The second phase consists in allocating the available targets, wherein we define and use three approaches: market-based, robot and task mean allocation-based, and balanced-based. Finally, the third phase involves the improvement in the solutions generated in the second phase. To validate the efficiency of the AHP-based approach, we used MATLAB to conduct an extensive comparative simulation study with other algorithms reported in the literature. The performance comparison of the three approaches shows a gap between the market-based approach and the other two approaches of up to 30%. Further, the results show that the AHP-based approach provides a better balance between the objectives, as compared to other state-of-the-art approaches. In particular, we observed an improvement in the total traveled distance when using the AHP-based approach in comparison with the distance traveled when using a clustering-based approach.     

Facile Synthesis and Antibacterial Activity of Bioplastic Membrane Containing In Doped ZnO/Cellulose Acetate Nanocomposite

The present work addresses a facile synthesis of Indium doped zinc oxide (IZO) cellulose acetate nanocomposite membrane. The membrane was prepared by casting method. Various weights of In:ZnO nanoparticles were added to solution formed by dissolution of cellulose acetate granules in acetone. The harvested membrane, after acetone evaporation, was characterized by various techniques including X ray diffraction, scanning electron microscopy, energy dispersive X ray and elemental mapping, Fourier transform infrared spectroscopy. The results show that the In:ZnO nanoparticles are well embedded in the cellulose acetate host matrix. The elemental mapping reveals that the nanoparticles are uniformly distributed. The optical characterization reveals the reduction of the transmittance in the UV (A and B range) of the CA/IZO composite with increasing the weight of the added IZO powder. This reduction was attributed to ZnO UV absorption. No noticeable peak assigned to ZnO bond are observed. However, IR peaks are shifted towards the higher wavenumber due to the change of the bonds environment with including IZO in the CA matrix. The antibacterial action of the synthetized nanocomposite membranes was tested against Escherichia coli (E. coli). Staphylococcus aureus (S. aureus). The assay results have shown that the membrane has no activity against (E. coli). In contrary, the synthetized membrane exhibits an interesting antibacterial activity against S. aureus. The inhibition region varies from 6 to 15 mm with increasing the weight ratio of filler. A zone of inhibition (ZOI) of 18 mm was observed for the membrane prepared with 30% wt. of In:ZnO. We noticed that the ZOI radius increases with the added weight of IZO. Due the settling down of the nanoparticles only one face of the membrane exhibits an antibacterial activity.

     

Tribological properties of silicon/silica heterostructures modified with covalent-bonded long alkyl chains

A method involving the grafting of long chain molecules on hydroxylated ceramic surfaces such as silica is proposed to improve the lubrication of microactuators. Preliminary experiments show that one monolayer of C₁₈ or C₂₂ molecules, chemically bonded, leads to an effective improvement in silica tribological properties, the friction coefficient decreasing from 0.5 to 0.1.