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Summary To meet the surging demand for artificial intelligence and cloud service, data centers have been expanding rapidly on recent years. Therefore, data center networks have received great attention recently and more challenges gradually emerged. The exiting technology of data center networks (DCNs) has presented two problems: high energy consumption and network load imbalance. Traditionally, the middle‐box hardware is dedicated and complexly merged, such as network load balancer and network energy optimizer. As an emerging architecture, software defined networks (SDNs) brings an opportunity to accomplish load balancing and energy optimization simultaneously with its characteristics. In this article, we propose a traffic flow management strategy which jointly considers energy optimization and load balancing. The strategy forwards traffic flows with maximum available bandwidth multipath routing to balance network load. We minimize activated links and switches to save energy by scheduling traffic flows. We jointly formulate these as an integer linear programming (ILP) problem. We propose a heuristic algorithm to handle the problem. The full simulation results reveal the high efficiency of our algorithm and the coexistence of network energy optimization and load balancing.

Nowadays, energy consumption has become an important issue in data center networks. The most promising energy-saving schemes are those that shut down unnecessary network devices and links while meeting the demand of traffic loads. Existing research mainly focuses on the strategies of energy savings in software-defined data center networks (SD-DCN). Few studies have considered both energy savings and the quality of service (QoS) of the traffic load. In this paper, we investigate the energy savings guaranteed by traffic load satisfaction ratio. To ensure the minimum-power consumption in data centers, we formulate the SD-DCN energy consumption optimization problem as an Integer Linear Programming model. To achieve a high success rate for traffic transmission, we propose three flow scheduling strategies. On this foundation, we propose a strategy-based Minimum Energy Consumption (MEC) heuristic algorithm to ensure the QoS satisfaction ratio in the process of energy optimization. The results show that our algorithm can save energy efficiently under the conditions of low traffic load and medium traffic load. Under high traffic load, our algorithm can achieve better network performance than existing solutions in terms of quality of service satisfaction ratio of flow allocation.

Ubiquitous internet access over the past decade has provided opportunities to learn languages online. However, most of the online language learning studies focus on higher education perspectives, while the related learner contribution on the commercial platform has yet to be explored. This study investigates Chinese adult learners' perception of learning English on the online course platform through a qualitative research approach. The semi-structured interview questions comprise five parts: learners' background, learning situation (frequency and time spent), assessment of instructors and teaching materials, preference of delivery model (with traditional classroom compared), and their attainment from the online learning platform. These findings can help platform operators better understand the perception of Chinese amateur adult learners and fill the literature gap to provide educators with insights and references on current research agendas.