Authors:Biraj Shougaijam, Salam Surjit Singh Pages: 159 - 170 Abstract: In this work, we present our results related to the development of Dye-Sensitized Solar Cells (DSSCs) based on vertically aligned TiO2-nanowire (NW) and Ag nanoparticle (NP) assisted vertically aligned TiO2-NW (TAT) photoanode fabricated by the glancing angle deposition (GLAD) technique on fluorine doped thin oxide (FTO) substrates. The scanning electron microscopy (SEM) analysis reveals that the Ag-NP assisted vertically aligned TiO2-NW photoanode was successfully deposited on FTO substrates. The average length and diameter of the NW have been measured to be ~ 350 nm and ~ 90 - 100 nm, respectively. Moreover, transmission electron microscopy (TEM) and X-ray diffraction (XRD) manifest the presence of small crystals of TiO2 and Ag. Further, the absorption spectrum analysis reveals that the incorporation of Ag-NP in TiO2-NW increases absorption in the visible region, but decreases the efficiency of the cell after the incorporation of the nanoparticle. The calculated bandgap of the annealed Ag-NP (30 nm) assisted TiO2-NW (TAT@30nm) sample from the photoluminescence (PL) graph is ~ 3.12 eV. Finally, it is observed that the TiO2-NW based DSSC device shows better performance in terms of photo conversion efficiency (PCE) compared to the TAT@30nm photoanode based device, with an efficiency of ~0.61 % from the former and ~ 0.24 % from the latter. This reduction in the efficiency of TAT@30nm based devices is due to the larger size of Ag-NP, in which the nanoaprticle acts as an electron sink and acts as a blocking layer. PubDate: 2023-06-29 Issue No:Vol. 36, No. 2 (2023)
Authors:Lalit Kumar, Vandana Nath, BVR Reddy Pages: 171 - 188 Abstract: Microstrip antennas have become ubiquitous in today's wireless communication world due to their low profile, low cost, and simplicity in fabricating on circuit boards. However, poor performance characteristics, such as limited bandwidth, low power handling capabilities, and low gain, limit their applicability in various instances. Path loss will be substantial in 5th generation (5G) wireless communication due to the utilization of high-frequency bands. A high-gain antenna with a small size is necessary to address this issue. A compact tri-band, slotted monopole antenna with high and consistent gain employing a defected ground plane structure (DGS) has been investigated and implemented in this study. This proposed antenna uses three inverted L-shaped stubs connected to the radiating element to cover the desired bands while keeping the antenna size small. The designed antenna has two key characteristics: (i) wide bandwidth and (ii) reasonable gain. The antenna covers 2.45 and 5.6 GHz WLAN, 2.4 GHz Wi-Fi, 2.5 and 5.2 GHz WiMAX and 3.7 GHz Sub-6 GHz of 5G for mobile communication. The overall substrate size of the antenna is 30 × 17 × 1.6 mm3and the electrical dimensions are 0.49 λL × 0.28 λL ×0.026 λL, where λL is the free space wavelength at 2.45 GHz. The measured reflection coefficient (S11 < -10dB) covers 2.4 - 2.52 GHz (bandwidth 112 MHz) and 3.4 - 4.1 GHz (bandwidth 700 MHz) and 5.2 - 6.6 GHz (bandwidth 1359 MHz) with a fractional bandwidth of 5.1 % at lower frequency band, 18.6 % at mid frequency band and 23.7 % at high frequency band. A prototype antenna has also been developed using an inexpensive, low-profile 1.6 mm thick FR-4 (εr = 4.4) substrate. The measured peak gains achieved are 1.35 dB at 2.45 GHz, 2.55 dB at 2.65 GHz and 3.8 dB at 5.5 GHz. The simulated results have been validated against actual experimental measurements, and the outcomes are consistent and match with certainty. The proposed antenna design is very compact and easy to fabricate due to the absence of vias. PubDate: 2023-06-29 Issue No:Vol. 36, No. 2 (2023)
Authors:Sujay Kumar Dolai, Arindam Mondal, Prasanta Sarkar Pages: 189 - 208 Abstract: In this work, a fractional-order controller (FOC) is designed in a discrete domain using delta operator parameterization. FOC gets rationally approximated using continued fraction expansion (CFE) in the delta domain. Whenever discretization of any continuous-time system takes place, the choice of sampling time becomes the most critical parameter to get most accurate results. Obtaining a higher sampling rate using conventional shift operator parameterization is not possible and delta operator parameterized discretize time system takes the advantages to circumvent the problem associated with the shift operator parameterization at a high sampling limit. In this work, a first-order plant with delay is considered to be controlled with FOC, and is implemented in discrete delta domain. The plant model is designed using MATLAB as well as in hardware. The fractional-order controller is tuned in the continuous domain and discretized in delta domain to make the discrete delta FOC. Continuous time fractional order operator (s±α) is directly discretized in delta domain to get the overall FOC in discrete domain. The designed controller in implemented using MATLABSimulink and dSPACE board such that dSPACEboard acts as the hardware implemented FOC. The step response characteristics of the closed-loop system using delta domain FOC resembles to that of the results obtained by continuous time controller. It proves that at a high sampling rate, the continuous-time result and discrete-time result are obtained hand to hand rather than the two individual cases. Therefore, the analysis and design of FOC parameterized with delta operator opens up a new area in the design and implementation of discrete FOC, which unifies both continuous and discrete-time results. The discrete model performance characteristics are evaluated in software simulation using MATLAB, and results are validated through the hardware implementation using dSPACE. PubDate: 2023-06-29 Issue No:Vol. 36, No. 2 (2023)
Authors:Sateesh Gudla, NageswaraRao Kuda Pages: 209 - 226 Abstract: Energy-efficient and reliable data routing is critical in Wireless Sensor Networks (WSNs) application scenarios. Due to oscillations in wireless links in adverse environmental conditions, sensed data may not be sent to a sink node. As a result of wireless connectivity fluctuations, packet loss may occur. However, retransmission-based approaches are used to improve reliable data delivery. These approaches need a high quantity of data transfers for reliable data collection. Energy usage and packet delivery delays increase as a result of an increase in data transmissions. An energy-efficient data collection approach based on a genetic algorithm has been suggested in this paper to determine the most energy-efficient and reliable data routing in wireless sensor networks. The proposed algorithm reduced the number of data transmissions, energy consumption, and delay in network packet delivery. However, increased network lifetime. Furthermore, simulation results demonstrated the efficacy of the proposed method, considering the parameters energy consumption, network lifetime, number of data transmissions, and average delivery delay. PubDate: 2023-06-29 Issue No:Vol. 36, No. 2 (2023)
Authors:Elson Avallone, Paulo Henrique Palota, Paulo César Mioralli, Pablo Sampaio Gomes Natividade, Jonas Rafael Antonio, José Ferreira da Costa, Sílvio Aparecido Verdério Junior Pages: 227 - 238 Abstract: Currently, the energy sector is the main responsible for the emission of carbon dioxide into the atmosphere. Therefore, to reverse this scenario, it is necessary to expand the use of renewable energy sources, such as wind energy. With that, the search for improving efficiency in wind turbines that work with low speed winds, make the Savonius turbine an advantageous option for presenting characteristics of low construction cost. This study aims to theoretically analyze a single model of vertical axis wind micro turbine using artificial wind. The wind power for 2 stages in this project was 0.063 W, as the power variation in relation to rotation is not linear. Another important factor to consider is that the overlap ratio of 30% collaborates a power reduction. Using the mathematical models, some results were theoretically analyzed through the Savonius turbine with central axis. The literature indicates that the most efficient turbine is a two-stage turbine with helical blades and without a central axis. PubDate: 2023-06-29 Issue No:Vol. 36, No. 2 (2023)
Authors:Bader Somaiday, Ireneusz Czajka, Muhammad A.R. Yass Pages: 239 - 251 Abstract: The efficiency of horizontal axis wind turbine (HAWT) blades is examined in this paper concerning the effect of cross-section airfoil type. Three dif-ferent airfoils were examined: symmetric (NACA 4412), asymmetric (NACA 0012), and supercritical (NACA 4412). (EPPLER 417). The anal-yses that were performed combined theory and experiment. Theoretical analyses were carried out using Fortran 90 code and the blade element momentum-based Qblade code. The blade was created using SolidWorks software and a 3D printer for testing purposes. The findings of experi-mental tests supported the conclusions of the theory. Research revealed that the EPPLER 417 blade, which has a supercritical airfoil, performed better than other examined objects. NACA 4412, NACA 0012, and EPPLER 417 each have a power coefficient of 0.516, 0.492, and 0.510. According to the experimental data, the EPPLER 417 airfoil outperforms other air-foils in terms of power and speed reduction. To calculate the deformation and stresses of the three blades with various cross sections, CFD analysis was done in ANSYS Workbench. The CFD results showed that NACA 4412 has the highest strength but EPPLER 417 was considered the optimum cross-section based on power generation and acceptable stress values. PubDate: 2023-06-29 Issue No:Vol. 36, No. 2 (2023)
Authors:Claudio Moraga, Fatima Zhora Hadjam Pages: 253 - 266 Abstract: Reversible Computing circuits are characterized by low power consumption and their proximity to circuits for quantum computing. The Fredkin gate was one of the earliest proposed controlled reversible circuits, which however, was soon superseded by the Toffoli gate, the NOT, and CNOT gates, which constituting a flexible functionally complete set could also realize the Fredkin gate as a building block. In quantum computing circuits, the Fredkin gate (under the name controlled SWAP) plays an important role regarding the superposition of states. The present paper studies extensions of the Fredkin gate in terms of mixed polarity in the reversible domain and an application in quantum computing. PubDate: 2023-06-29 Issue No:Vol. 36, No. 2 (2023)
Authors:Nikola Mitrović, Milan Đorđević, Sandra Veljković, Danijel Danković Pages: 267 - 284 Abstract: This paper gives insight on the WebSocket communication method in Internet of Things system, where the hardware part of the system is based on ESP32 microcontroller. Method of implementation is discussed and the reliability of the real-time data transfer in Wi-Fi networks is tested and compared with the long-polling method. Special circuit is designed with the goal to stress the hardware part of the system and the client-server communication link in order to enable proper comparison of data transfer methods. For the comprehensive testing of the real-time data ow, a web server application is designed and used to visualize received data. Impact of RSSI on transfer methods is discussed as well. Eciency of the WebSocket method is discussed and then compared to the long-polling method. PubDate: 2023-06-29 Issue No:Vol. 36, No. 2 (2023)
Authors:Miloš Radmanović Pages: 285 - 298 Abstract: Bent Boolean functions exist only for an even number of variables, moreover, they are unbalanced. Therefore, they are used in coding theory and in many areas of computer science. General form of bent functions is still unknown. One way of representing Boolean functions is with a reduced ordered binary decision diagram (ROBDD). The strength of ROBDDs is that they can represent Boolean functions data with a high level of redundancy in a compact form, as long as the data is encoded in such a way that the redundancy is exposed. This paper investigates characteristics of bent functions with focus on their ROBDD parameters. Decision diagram experimental framework has been used for implementation of a program for calculation of the ROBDD parameters. The results presented in this paper are intended to be used to create methods for the construction of bent functions using a ROBDD as a data structure from which the bent functions can be discovered. PubDate: 2023-06-29 Issue No:Vol. 36, No. 2 (2023)
Authors:Marko Milivojčević, Emilija Kisić, Dejan Ćirić Pages: 299 - 314 Abstract: In this paper a portable system for acquisition of sound generated by passenger vehicles powered by internal combustion engines is described and analyzed. The acquisition system is developed from scratch and tested in order to satisfy the requirements such as high-quality of audio recordings, high mobility, robustness and privacy respect. With this acquisition system and adequate signal processing, the main goal was to collect a large amount of clear audio recordings that will form a quality dataset. In further research, this dataset will be used for machine learning model training and testing, i.e. for developing a system for automatic recognition of the type of car engine based on fuel. PubDate: 2023-06-29 Issue No:Vol. 36, No. 2 (2023)
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