Department of Electrical and Electronics Engineering

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Subject: search.filters.subject.Energy harvesting

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Now showing 1 - 8 of 8
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    Modification of Electronic Properties of Graphene with Porphyrin Self-Assembled Monolayers and Photoinduced Interactions
    (American Scientific Publishers, 2012-07) Rao, V. Ramgopal
    Solution processable reduced graphene oxide (RGO), with its unique electrical and structural properties is being considered in large scale device fabrication. The research developments in the formation and characterization of nanoelectronic devices with self-assembled monolayers (SAMs) of porphyrin can have foundations for future high speed electronics, alternative energy sources and sensors. In this work, we present the effect porphyrin monolayer functionalization on the electronic properties of RGO. Electrical transport measurements show that this dipolar monolayer on RGO induces doping and the capacity to tune the electronic properties of RGO may have important applications in future graphene devices, sensors and energy harvesting. Also, carrier transfer from excited zinc porphyrin molecules to carbon-based nanostructures is demonstrated on transistors comprising physiosorbed RGO on zinc porphyrin SAM.
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    Low Cost, Large Area, Flexible Graphene Nanocomposite Films for Energy Harvesting Applications
    (IEEE, 2017-03) Rao, V. Ramgopal
    In this paper, we report a robust and a low-cost spin coating approach for fabrication of large area flexible piezoelectric nanocomposite generator device for harvesting biomechanical motions. In order to develop the piezoelectric nanocomposite, ZnO and BaTiO 3 were used as filler materials for realization of piezoelectric nanogenerator. Serial stretching and bending tests over these devices illustrated generation of maximum open-circuit voltage of ∼237 and ∼736 mV for ZnO and BaTiO 3 , respectively. Furthermore, we also demonstrated a 2 × enhancement in output voltage performance of nanogenerator by adding graphene platelets to these diphasic piezoelectric nanocomposite systems.
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    Analysis of angular position, dimension and material of a cantilever piezoelectric energy harvester
    (Taylor & Francis, 2018) Yenuganti, Sujan
    The performance of an angular vibrating single piezoelectric cantilever beam energy harvester in a flexural mode was analyzed. In this research the approaches of theory, finite element, and experiment have been undertaken to study the effects of angular position, mechanical properties, and dimensions on the output power and resonance frequency of a piezoelectric cantilever beam. The phase shift is an important phenomenon observed in this system because of the angular position of the beam about its longitudinal axis. Frequency shift due to the angular position is usually observed in experiments. However, it has not been studied theoretically until now. The angular position not only affects the resonance frequency but also the amount of output power from the lead zirconate titanate ceramic bonded on it. Furthermore, beam and piezoelectric dimensions have a major effect on power output and resonance frequency. Another aspect considered in this research is the effect of materials on power and frequency which have been studied for aluminum, copper, and steel.
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    Energy harvesting relay outage probability analysis of cooperative communication system over small and large scale fading channels
    (IEEE, 2017) Bitragunta, Sainath
    We consider an energy harvesting (EH) relay-assisted, two hop, cooperative communication system. For it, we analytically characterize EH relay outage probability when the source device transmissions undergo small scale fading as well as large scale fading. In the analysis, we develop simple yet insightful upper bound for the EH relay outage probability. Furthermore, we investigate asymptotic outage probability of EH relay. We validate our analytical results with Monte-Carlo simulations. Assuming other system parameters fixed, our results show that the EH relay outage probability decreases with the increase in the harvesting power.
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    Optimizing the Order of Modulation for Minimized Distortion in Green Communication Networks
    (IEEE, 2018) Bitragunta, Sainath
    Energy is required for transmission of data over a wireless channel. This energy can be obtained using fixed batteries or via harvesting energy. In this paper, we optimize the energy distribution to minimize the overall distortion in a wireless network. The network model has energy harvesting nodes which transmit data in a time division multiple access (TDMA) scheme. First, we establish a relation between allocated energy and normalized minimum distortion by assuming a fixed battery system. We then use this relation to optimize the energy distribution to minimize overall distortion in an energy harvesting system. Following that, we incorporate path loss in our model and simulate the system to decide the optimum order of quadrature amplitude modulation (QAM), given a bit error rate threshold. This work not only models efficient usage of harvested energy but also ensures optimal utilization of the available bandwidth, while minimizing overall distortion.
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    Energy Harvesting, Hybrid, Cooperative Wireless System Modeling and Outage Performance Analysis
    (IEEE, 2018) Bitragunta, Sainath
    We consider radio frequency-energy harvesting (RF-EH) non-cooperative system, and, an RF-EH relay-assisted, two hop, hybrid cooperative communication system that comprises of a digital link, and an analog link that uses phase modulation. For the two system models, we analytically characterize outage probability when the node transmissions undergo small scale fading as well as path loss. In the analysis, we develop simple yet insightful closed-form expressions for outage probability. We validate our analytical results with Monte-Carlo simulations. Our numerical results show that the outage can be significantly improved by using pre-emphasis and de-emphasis (PE-DE)
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    Energy Harvesting Cooperative Wireless Systems: Probabilistic Modeling and Statistical Analysis
    (IEEE, 2019) Bitragunta, Sainath
    In this work, we consider a two-hop cooperative wireless system that consists of multiple energy harvesting (EH) relays. The system uses a time-switching based relaying protocol for EH and information processing at the amplify-and-forward (AF) relay nodes. For it, we formulate an order statistics problem of finding the distribution of maximum energy harvested among several EH relay nodes by considering two different fading models, namely, path loss and Rayleigh fading model, path loss and shadow fading model. For these models, we derive analytical expressions for the mean value of maximum harvested energy distribution. Furthermore, we also present an insightful outage analysis and numerical results to validate the analytical expressions. The analysis that we present lead to an essential application of the best EH relay selection in EH cooperative wireless systems and networks.
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    Spectral Efficiency Optimization and Analysis of Time Switching-Based, Energy Harvesting Spectrum Sharing Cooperative Wireless System
    (IEEE, 2021) Bitragunta, Sainath
    Simultaneous wireless information and power transfer (SWIPT) has gained momentum as a novel and energy efficient technique to restore energy as well as transfer data in communication networks. In this paper, we consider an energy harvesting (EH) relay assisted collaborative wireless system which operates as a secondary network in underlay mode in a spectrum sharing environment. The collaborative system has a source node, a destination node, and multiple EH relays that are nonregenerative, interference-constrained, and use time-switching architecture to harvest energy and receive information from the source node. We select the relay with the maximum harvested energy for further transmission of data to the destination node. For the secondary cooperative EH system, we provide the average spectral efficiency analysis and propose an optimal time switching ratio policy for the selected EH relay that delivers superior performance than benchmark approaches, namely, the random selection and fixed time switching ratio approach. The proposed policy motivates its application in SWIPT based collaborative and spectrum sharing systems.