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.

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Thermoelectric technology, a solid state technology that converts heat energy into usable electricity, have gained a great attention in the field of renewable energy resources. This paper presents an importance of phase change material (PCM) of D-Mannitol attached in the hot side of commercially available Bi2Te3 based thermoelectric module on the recovery of transient heat so as to boost the conversion efficiency. The open circuit voltage and short circuit current of TEG attached in the D-Mannitol were recorded for heating and cooling in the temperature range of 323 K–450 K. During heating cycle, the thermal energy produced by external heater is stored in the PCM which is used as a heat source for power generation during cooling. Particularly, the maximum open circuit voltage drawn in presence of external heater is 1.23 V which moderately reduces to 0.4 V after 15 min. The maximum power drawn in the heater on and heater off are 20.8 mW and 0.48 mW respectively.

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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Thermoelectric generators (TEGs) have received a great attention in the field of renewable energy resources due to their superior ability of converting untapped waste heat into usable electricity. In order to boost the conversion efficiency of TEG and to retrieve the transient heat, this paper demonstrates the role of nanostructured graphite (G) and graphene oxide (GO) decorated phase-change material (PCM) of D-mannitol attached with the hot end of commercial thermoelectric module on enhancement of conversion efficiency and power output. Presence of G and GO on the matric of D-mannitol has been confirmed by powder XRD and FE-SEM. The open circuit voltage ( V oc ) and short circuit current ( I sc ) of TEG attached with PDM, G/PDM, and GO/PDM were recorded for the heating and cooling cycles in the temperature range of 325-450 K. Particularly, the experimentally measured V oc and I sc of TEG with only PDM are 1.23 V and 90 mA, respectively, for the temperature difference of ΔT ∽ 118 K, whereas the maximum V oc of TEG attached with GO/PDM drawn in presence of an external heater is 4.5 V for ΔT ∽ 118 K. Further, the maximum output power of TEG with GO-PCM drawn in the heater-ON and heater-OFF is 1012.5 mW and 450 mW, respectively.

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