Despite unique energy-saving dispositions of cluster-based routing protocols, clustered wireless sensor networks with static sinks typically have problems of unbalanced energy consumptions, as the cluster head nodes around the sink are typically loaded with traffic from upper levels of clusters. This results in reduced lifetimes of the nodes and deterioration of other crucial performances. Meanwhile, it has been inferred from current literature that dedicated relay cooperation in cluster-based wireless sensor networks guarantees longer lifetime of the nodes and more improved performance. Therefore, to attain further enhanced performance among the current schemes, a lifetime-enhancing cooperative data gathering and relaying algorithm for cluster-based wireless sensor networks is proposed in this article. The proposed lifetime-enhancing cooperative data gathering and relaying algorithm shares the nodes into clusters using a hybrid K-means clustering algorithm that combines K-means clustering and Huffman coding algorithms. It makes full use of dedicated relay cooperative multi-hop communication with network coding mechanisms to achieve reduced data propagation cost from the various cluster sections to the central base station. The relay node selection is framed as a NP-hard problem, with regard to communication distances and residual energy metrics. Furthermore, to resolve the problem, a gradient descent algorithm is proposed. Simulation results endorse the proposed scheme to outperform related schemes in terms of latency, lifetime, and energy consumption and delivery rates.
This paper develops a test bed for a hybrid vehicle's power train along with a switching control methodology to address the time delay experienced in electrical switching between engine and motor power to achieve smooth power transmission to the wheels, thus reducing fuel consumption. A complete test bed for the power train is designed and fabricated. A conventional sequential-based switching control algorithm is developed to operate the system with a motor at low speeds and the engine at higher speeds, using the number of rotations per unit time as the switching parameter. The logged output is analyzed and the performance efficiency of the hybrid vehicle powertrain is compared against conventional internal combustion (IC) engines.
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