Vehicle routing is a class of combinatorial optimization problems arising in the industry of transportation and logistics. The goal of these problems is to compute an optimal route plan for a set of vehicles for serving transport requests of customers. There are many variants of the vehicle routing problems: routing for delivering goods, routing for demand responsive transport (taxi, school bus, …). Each problem might have different constraints, objectives. In this paper, we introduce a Constraint-Based Local Search (CBLS) framework for general offline and online vehicle routing problems. We extend existing neighborhood structures in the literature by proposing new neighborhoods to facilitate the resolution of different class of vehicle routing problems in a unified platform. A novel feature of the framework is the available APIs for online vehicle routing problems where requests arrive online during the execution of the computed route plan. Experimental results on three vehicle routing problems (the min-max capacitated vehicle routing problem, the multi-vehicle covering tour problem, and the online people-andparcel share-a-ride taxis problem) show the modelling flexibility, genericity, extensibility and efficiency of the proposed framework.

This article presents the results of a study that evaluated the effects of using sea sand with varying contents of chloride ions on the properties of concrete, including physical and mechanical properties as well as durability. The study was carried out on the sea sand samples with different chloride ion contents, including as-received sea sand samples with a chloride ion content of approximately 0.15%, two washed (desalted) sea sand samples with chloride ion content of 0.024% and 0.05%, and sea sand samples added with chloride salt (0.375%), which were then compared with river sand samples. The sand samples had approximately the same fineness modulus ranging from 2.3-2.5. The research results indicated that compared with washed sea sand and river sand, concrete mixes using sea sand with high chloride ion content increased the mixing water and reduced the slump retainability of the fresh concrete. Furthermore, early compressive strength (7 days) increased but late age strength (91 and 365 days) decreased in both standard curing and wet-dry circle curing cases. Additionally, the impermeability (water and chloride ion) and the ability to protect the reinforcement from corrosion in concrete were reduced when using sea sand with high chloride ion content compared to washed sea sand and river sand.

No abstract

No abstract

No abstract