Multi-depot heterogeneous vehicle routing problem with simultaneous pickup and delivery and time windows (MDHVRPSPDTW) is an extension of vehicle routing problem (VRP), MDHVRPSPDTW mathematical model was established. The improved genetic algorithm (IGA) is proposed for solving the model. Firstly, MDHVRPSPDTW is transferred into different groups by the seed customer selecting method and scanning algorithm (SA).Secondly, IGA based on elite selection and inversion operator is used to solve the model, and then cutting merge strategy based on greedy thought and three kinds of neighborhood search methods is applied to optimize the feasible solutions further. Finally, 3-opt local search is applied to adjust the solution. The proposed IGA has been test on a random new numerical example.The computational results show that IGA is superior to branch and bound algorithm (BBD) by Lingo 9.0 in terms of optimum speed and solution quality, and the model and the proposed approach is effective and feasible.
The Social Responsibility (SR) commitments of Higher Education Institutions (HEIs) alongside their long-standing functions of teaching and research have been recognized in literature. However, University Social Responsibility (USR) remains a relatively unexplored topic, especially in the post-conflict societies of the Great Lakes Region of East Africa (GLREA). The main objective of this paper is to document USR best practices, challenges and opportunities in GLREA universities. To reach this objective, a search was conducted in the major academic databases, where ten studies out of 93 found from 2000 to 2020 were included for review. Additionally, universities’ website materials, particularly Vision and Mission Statements (VMS) were considered to complement the review in a well established sense of USR in GLREA universities. A narrative review was conducted because quantitative data were not feasible due to a significant level of heterogeneity between the included studies. The overall findings indicated that the scholarship of engagement in the regional context is not a luxury of HEIs as it is in many western universities, but rather a necessity in countries which are still undergoing the early stages of reconstruction. Specifically, the results obtained were twofold: First, the integrated SR in GLREA universities is an emerging agenda, despite its potential for growth. Second, the development of USR in the GLREA is connected to and influenced by the history of African Higher Education, and the institutional traces of that history’s influence can be found in GLREA. Finally, recommendations for USR practitioners are given, and a conclusion is drawn
Aiming at vehicle routing problem (VRP) with many extended features is widely used in actual life, multi-depot heterogeneous vehicle routing problem with soft time windows (MDHIVRPSTW) mathematical model is established. An improved ant colony optimization (IACO) is proposed for solving this model. Firstly, MDHIVRPSTW was transferred into different groups according to nearest depot method, then constructing the initial route by scanning algorithm (SA). Secondly, genetic operators were introduced, and then adjusting crossover probability and mutation probability adaptively in order to improve the global search ability of the algorithm. Moreover, smooth mechanism was used to improve the performance of ant colony optimization (ACO). Finally, 3-opt strategy was used to improve the local search ability. The proposed IACO has been tested on a 32-customer instance which was generated randomly. The experimental results show that IACO is superior to other three algorithms in terms of convergence speed and solution quality, thus the proposed method is effective and feasible, and the proposed model is better than conventional model.
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