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Fuzzy Based Network Assignment and Link-Switching Analysis in Hybrid OCC/LiFi System
摘要： In recent times, optical wireless communications (OWC) have become attractive research interest in mobile communication for its inexpensiveness and high-speed data transmission capability and it is already recognized as complementary to radio-frequency (RF) based technologies. Light fidelity (LiFi) and optical camera communication (OCC) are two promising OWC technologies that use a photo detector (PD) and a camera, respectively, to receive optical pulses. These communication systems can be implemented in all kinds of environments using existing light-emitting diode (LED) infrastructures to transmit data. However, both networking layers suffer from several limitations. An excellent solution to overcoming these limitations is the integration of OCC and LiFi. In this paper, we propose a hybrid OCC and LiFi architecture to improve the quality-of-service (QoS) of users. A network assignment mechanism is developed for the hybrid system. A dynamic link-switching technique for efficient handover management between networks is proposed afterward which includes switching provisioning based on user mobility and detailed network switching flow analysis. Fuzzy logic (FL) is used to develop the proposed mechanisms. A time-division multiple access (TDMA) based approach, called round-robin scheduling (RRS), is also adopted to ensure fairness in time resource allocation while serving multiple users using the same LED in the hybrid system. Furthermore, simulation results are presented taking different practical application scenarios into consideration. The performance analysis of the network assignment mechanism, which is provided at the end of the paper, demonstrates the importance and feasibility of the proposed scheme.
关键词： fuzzy logic,network assignment,hybrid system,optical wireless communications,QoS,LiFi,OCC,link-switching
更新于2025-09-04 15:30:14
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Prediction of Adsorption Probability of Oxidizing and Reducing Species on 2D Hybrid Junction of rGO-ZnO from First Principle Analysis
摘要： The target of this paper is to theoretically investigate the probability of gas (both oxidizing and reducing) adsorption on the van der Waals (vdW) heterojunction formed between p-type rGO and n-type 2D-ZnO, using density functional theory (DFT) based first principle calculation employing Virtual Nanolab (VNL) Atomistix Toolkit (ATK) (v2016.4). Two types of heterostructures are considered viz. heterostructure type-1 where hydroxyl group (sp2) is at the edge of the reduced graphene oxide (rGO) and heterostructure type-2 where hydroxyl group (sp3) is perpendicular to the plane of rGO. Adsorption energy, charge transfer and the distance of the nearest atom from the adsorbent are calculated for oxidizing (NO2 as the test case) and reducing (NH3 as the test case) species and compared with that of Oxygen on rGO/2D-ZnO heterostructures as well as on its individual constituent (rGO nanoflakes and 2D-ZnO, separately). Like 2D-ZnO, heterostructure type-1 was also found to be selective towards NO2 with almost three times and five times higher adsorption energy than that of 2D-ZnO and rGO, respectively. On the other hand, it was found that charge distribution in the underlying 2D-ZnO of heterostructure type-2 remained almost unaltered even after gas adsorption and therefore lead to insignificant improvement compared to its 2D-ZnO counterpart.
关键词： gas adsorption probability,charge transfer,van der Waals heterostructure,Density functional theory,rGO-ZnO hybrid system
更新于2025-09-04 15:30:14
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[IEEE 2018 2nd International Symposium on Multidisciplinary Studies and Innovative Technologies (ISMSIT) - Ankara, Turkey (2018.10.19-2018.10.21)] 2018 2nd International Symposium on Multidisciplinary Studies and Innovative Technologies (ISMSIT) - Optimal Design of a Rooftop Wind-PV Hybrid System to Meet Energy Demand for a Typical Residential Home in 20-Year Lifetime Projection
摘要： The need for electrical power gradually increases every year due to population growth and economic development in particular in developing countries. The primary sources of electricity are usually fossil fuels such as coal, natural gas, oil etc. and major part of them is imported by those countries. This is unfortunately a typical indication of the energy dependence and play strategic role in economic development of the developing countries since some cannot switch to renewable energy use despite they have abundant renewable energy potential. The fact that the use of renewable energy is not widespread in those countries and it can be seen as not making enough investment by the government or private sector. This potential can be utilized by using on-grid/off-grid renewable systems in particular wind-PV systems ranging from power ratings of 1 to 10 kW in remote areas. To make such systems economic, power balance between generation and consumption should be maintained at hourly time slots in the day. One way to do that is to solve a discrete optimization problem and the solution can be achieved by a mathematical model satisfying the given constraints in a certain location. Unit sizing of a low power off-grid renewable system to meet power demand for a typical residential home in a location is achieved and the outcomes are meaningful and encouraging for widening renewable energy applications worldwide.
关键词： electric generation,metaheuristic techniques,optimal design,rooftop wind-PV hybrid system,renewable energy
更新于2025-09-04 15:30:14