Search

Highlights • A succinct and efficient Opposition-Based Learning strategy is inherited in the algorithm. • A novel efficient strategy called Global Grid Ranking is proposed. • A charming multi-objective optimization algorithm called MOWOA is demonstrated. Abstract Nature-inspired computing has attracted a lot of research effort especially for addressing real-world multi-objective optimization problem (MOP). This paper proposes a new nature-inspired optimization algorithm which is named opposition-based multi-objective whale optimization algorithm with global grid ranking (MOWOA). The proposed approach utilizes several parts to enhance the performance in optimization. First, the efficient evolution process is inherited from the single objective whale optimization algorithm(WOA). Second, opposition-based learning(OBL) is applied into the algorithm. Meanwhile, a novel mechanism called global grid ranking(GGR) which is inspired by grid mechanism has been incorporated into the proposed algorithm. To show the significance of the proposed algorithm, MOWOA is tested on a diverse set of benchmark with a series of well-known evolutionary algorithms and the influence of each individual strategy is also verified through 14 benchmarks. Moreover, the new proposed algorithm is also applied to the simple data clustering problem and a real-world water optimization problem in China. The results demonstrate that MOWOA is not only an algorithm with well performance for bench-mark problems but also expected to have a more wide application in real-world engineering problems. [ABSTRACT FROM AUTHOR]

Terahertz (THz) band communication has been envisioned as a key wireless technology for providing unprecedented high data rates. However, due to the severe path loss, the transmission distance in THz band is very limited. Therefore, the beamforming techniques are explored to enlarge the communication range in THz networks, particularly employed at Access Points (APs). Interference is a critical factor affecting the performance of THz networks. In this paper, the interference and the coverage probability are investigated for the THz band communications with beamforming APs. First, based on the Line-of-Sight (LoS) and Non-Line-of-Sight (NLoS) ray propagation models of THz signals, the interferences from neighboring users and beamforming APs are modeled in closed forms based on stochastic geometry methods. Then, the Signal-to-Interference-plus-Noise-Ratio (SINR) and the coverage probabilities are further derived based on the THz channel and interference model. Extensive simulations are carried out to evaluate the interference and coverage for the THz band communications with beamforming APs, for the different system parameters, which include SINR threshold, density of APs, transmission frequency, gain of beamforming AP, density of users and radius of interference area. Learning from the simulation results, high density of APs with a small beam-width and the transmission at THz frequencies with low absorption efficient, such as 0.67 THz, are recommended to mitigate the interference and achieve a better coverage performance. [ABSTRACT FROM AUTHOR]

Many real-world networks are embedded in spaces. Recent studies have found that spatial characteristics are closely related to network features. Bus transport networks (BTNs) are typical spatially embedded networks, but their spatial characteristics are commonly disregarded in previous researches. In this paper, we propose a new spatial representation model for BTNs with information on the geographical location of bus stations and routes, for which we named as the ES model. The new model aids in the study of real-world BTNs. By performing a statistical study with the new representation model on three typical BTNs in China, namely the Beijing, Shanghai and Hangzhou BTNs, we identify some network features that are consistent with those revealed by previous studies, as well as some new features such as high clustering of short-distance station pairs (SSPs) and small average number of bus routes in a path. The result shows that the existence of SSPs can significantly influence the characteristics of BTNs. Besides, with the help of the ES model, we designed a new transfer algorithm for BTNs. [ABSTRACT FROM AUTHOR]