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The flexible periodic vehicle routing problem (FPVRP) is an extension of the classic VRP in which customers are visited periodically in the course of a given time horizon. Periodicity and flexibility in providing services are two main features of the FPVRP, which introduce new challenges in solving this problem. To the best of our knowledge, there is only one single-solution-based algorithm in the literature for solving the FPVRP. In this paper, another technique called the MA-FPVRP is proposed for tackling this problem. Our population-based approach is a memetic algorithm made up of two main components: a genetic procedure that aims to find a suitable sequence of visits for each route, and a local search procedure consisting of four moves whose prime goal is to guide the search toward the promising areas. Considering 45 standard benchmark instances with unknown optimal solutions, the MA-FPVRP outperforms the preceding method in terms of both the solution quality and execution time. Using this evolutionary scheme, the average relative percent deviation (RPD) to the best-known solution values decreases from 0.52% to 0.15%, and the average execution time improves by approximately 31%. For all 10 large instances of the FPVRP, new best results are found using our algorithm. Considering the remaining 35 small and medium-size instances, our approach is superior to the previous method in terms of the solution quality, and it is more than two times faster. Besides, using the MA-FPVRP, new best solutions are obtained for 5 out of these 35 instances. [ABSTRACT FROM AUTHOR]

For the first time, a bio-photo-catalyst is synthesized in a microfluidic platform. The microchannel, which is wall-coated by in situ synthesized bio-photo-catalyst is used as an opto-fluidic reactor for amoxicillin degradation. Analyses including SEM, XRD, FTIR, Raman, UV–Vis spectra, and DLS have been used to characterize samples. The structure and morphology of TiO2 in microfluidic assisted synthesis are studied at 70–120 °C. The results show that both single-crystalline anatase sample and two-phase samples of anatase and rutile can be attained. According to SEM images, the smallest size and the narrowest particle size distribution (0.86 nm ± 0.14 ) is achieved by synthesis at 70 °C. Elemental mapping of Ti shows a uniform coating layer on inner walls. Raman signals besides the primary amines in FTIR results show the biological activity of the cross-linked Glucose oxidase (GOx), which is aimed for situ generation of H2O2. FTIR comparison of bulk and spiral microfluidic synthesized ZnO indicates identical bonds. SEM-coupled with performance experimentation reveal that by regulating the flowrate of spiral micromixer for ZnCl2 at 25 µl/min and NaOH at 50 µl/min, the narrowest size distribution and best the bio-photo-catalytic performance of ZnO nanoparticles is observed. [ABSTRACT FROM AUTHOR]

Dial-a-Ride Problem (DARP) is one of the classic routing problems with pairing and precedence constraints. Due to these types of constraints, it is quite challenging to design an efficient evolutionary algorithm for solving this problem. In this paper, a genetic algorithm in combination with a variable neighborhood descent procedure is suggested to solve the DARP. This algorithm, which is called Hybrid Genetic Algorithm (HGA), is independent of any repairing procedure or user-defined penalty factors. Instead, it uses the constraint dominance principle with respect to the number of unserved requests. Our algorithm employs an adaptive population management technique which takes into account not only the quality of solutions but also their contribution in the diversity level. To do so efficiently, this population management technique utilizes a simple arc-based representation for the DARP solutions. A route-based crossover procedure known as Route Exchange Crossover is used in the HGA. This crossover method is thoroughly compared with five other crossover techniques including a new one called Block Exchange Crossover. The HGA produces competitive solutions in comparison with the state-of-the-art methods for tackling the DARP and Heterogeneous DARP (H-DARP). It obtains the optimal solutions of all the small and medium size standard instances of the DARP and finds new best results for two large ones with unknown optimal solutions. Moreover, for 12 out of 24 new instances of the H-DARP, the best known solutions are improved using the HGA. [ABSTRACT FROM AUTHOR]

For the first time, a review of microheater design and its implementation for nanowire synthesis has been investigated. The recent developments on the effect of temperature, precursor flow rate, and synthesis time on the size and size distribution of nanowires have been studied. The essential components of the microheater include a substrate, insulating layer(s), and microheater area. A guide for material selection associated with different components of the device including the heating element, conducting pads, membrane, substrate, and oxidation layer has been addressed. The current progress on electrode patterns and microheater fabrication methods has been evaluated. The insights into microheater calibration curves have been reviewed. Finally, the economic aspects including the microheater market and fabrication costs have been presented. [ABSTRACT FROM AUTHOR]

In this work, TiO and doped TiO photocatalysts (Fe/TiO and Cu/TiO) were synthesized by the sol-gel method. The main objective of this study was to investigate the influence of dopants on the structure, morphology, and activity of the catalysts in powder and immobilized states. XRF, XRD, and SEM methods were used to characterize the catalysts. The structure and phase distribution of the nanocrystalline powders were identified by XRD. Nanoparticles crystallite size and the degree of crystallinity were affected by doping. The anatase contents of catalysts were achieved as follows: TiO (5.89 %) < Fe/TiO (42.17 %) < Cu/TiO (70.28 %). It was indicated that the activity of the catalysts strongly depends on the anatase content. Under the same circumstances, copper-modified TiO exhibited a twofold higher photocatalytic activity compared with TiO. The nanostructured catalysts were immobilized on light expanded clay aggregate (LECA) granules in order to investigate the effect of a novel support on the activity of the catalysts. Morphological changes are recognizable in the SEM images. Activity tests indicated that the best catalytic performance was assigned to Cu/TiO/LECA. After 120 min of irradiation, 61 % degradation of phenol in synthetic wastewater was achieved. The high photocatalytic activity of Cu/TiO/LECA confirms that LECA is as an excellent support. [ABSTRACT FROM AUTHOR]