Motihari College of Engineering, Motihari is a Government Engineering College fully funded by the government of Bihar, India. It is managed by Department of Science and Technology, Bihar, along with 38 Government Engineering Colleges of Bihar. The college is affiliated to Aryabhatta Knowledge University, Patna and approved by AICTE, New-Delhi..
Light fidelity (Li-Fi) is an emerging optical wireless communication technology that utilizes visible light for high speed data transmission, addressing the limitations of traditional radio frequency (RF) based systems such as Wi-Fi and 5G. Given the increasing demand for wireless data and the congestion of RF spectrum, Li-Fi offers a promising solution by leveraging light-emitting diodes (LEDs) for simultaneous illumination and communication. This study evaluates the performance of a Li-Fi system through extensive simulations, analyzing key metrics such as quality factor (Q-factor), bit error rate (BER), eye diagram, and coverage area. The results indicate that the system supports a data rate of 10 Gbps up to a height (i.e., range) of 6.5 m when operating at a beam divergence angle of 523.59 mrad (i.e., 30^∘ ), achieving a Q-factor of 6.59 and a coverage area of 46.69 m ^2 . However, as the transmitter height increases, BER rises while Q-factor declines due to free-space losses and signal dispersion. A higher divergence angle enhances coverage but demands increased transmission power for maintaining signal integrity. At 6.5 m and 523.59 mrad, the system achieves a BER of 2.15 × 10^- 11 with a transmitted power of 3 W, confirming its feasibility for high-speed indoor communication.
Abstract A dual band circularly polarized coplanar waveguide—fed microstrip patch antenna consisting of four inverted L grounded strips near the corners and a multi-level vertical stack excited by a 50 Ω impedance microstrip feedline is proposed. The complete dimension of the proposed antenna is only 60 × 60 × 0.8 mm 3 . The Circular Polarization is achieved by embedding a pair of inverted—L grounded strips into the square slot and by altering the dimensions of vertical stub. The frequency bandwidth of the proposed antenna is achieved for two bands, from 2.79 GHz to 3.99 GHz with resonating frequency at 3.3 GHz and 3.5 GHz for 5G and WiMAX applications respectively and the other one is from 6.94 GHz to 8.28 GHz featuring a resonating frequency of 7.9 GHz, this design is primarily utilized for satellite communication within the lower X-band for fixed satellite service (FSS) uplink. The uplink frequency from Earth to satellite ranges from 7.9 GHz to 8.4 GHz, making it ideal for applications such as FSS uplink. VSWR ⩽2 dB is achieved for both the bands and axial ratio (AR) ⩽3 dB is from 2.85 GHz to 3.85 GHz and 7.85 GHz to 8.33 GHz respectively. Performance of the fabricated antenna is experimentally validated and its Return Loss, VSWR, AR, Radiation Pattern, Gain, Radiation Efficiency, Surface Current are also observed.
Effective maintenance of roads is fundamental to transportation infrastructure with significant impact on safety and mobility. Notably, timely and precise pothole detection is essential for preventing road hazards and maintaining driving comfort. Traditional pothole detection methods are time- consuming and labor-intensive, prompting exploration of deep learning (DL)-based approaches for real-time and efficient pothole identification. In this study, three advanced “you only look once” (YOLO) models—YOLOv10n, YOLO11n, and YOLO11s—were evaluated on a dataset comprising of 13 767 images. Model performance was assessed using mean average precision (mAP) at an intersection over union (IoU) threshold of 0.5 (mAP@50). At this threshold, detections with an IoU ≥ 0.5 were considered true positives. In addition, precision, recall, and F1-score (the harmonic mean of precision and recall) were also reported. Experimental results indicate that YOLO11n outperforms the other models, achieving a precision rate of 100%. Further-more, YOLO11n, with its compact size of 5.6 MiB and an inference time of 1.1 ms, demonstrated an optimal balance between detection accuracy and computational efficiency, making it suitable for real-time deployment. To enhance the system’s effectiveness, global positioning system (GPS) tagging using geographic information systems (GISs) was integrated for accurate pothole mapping, and depth cameras were utilized to improve detection reliability. The model was deployed on Streamlit Cloud with an intuitive interface that allows users to upload road videos with GPS data, detect potholes, visualize results on maps and heatmaps, and download processed outputs. Overall, the findings establish YOLO11n as a highly effective solution for automated pothole detection, providing a fast, scalable, and efficient tool for proactive road maintenance on edge networks.
In this paper, we present a comprehensive comparative analysis of multilevel inverter (MLI) architectures, examining their operating principles, design variations, and performance characteristics with a focus on renewable energy integration. Specifically, we analyze representative topologies, including cascaded H-bridge, neutral-point-clamped, and flying-capacitor inverters, to highlight their distinct advantages and limitations. These MLIs synthesize AC output from multiple DC voltage levels, significantly enhancing power quality and reducing total harmonic distortion (THD) compared to conventional two-level (square-wave) inverters. However, these benefits come at the cost of greater circuit complexity, higher component counts, and the need for advanced control strategies, which may impact system reliability. Despite these challenges, MLIs are increasingly adopted in solar and wind energy systems as well as medium- and high-voltage applications because of their superior ability to handle fluctuating power outputs. Conversely, traditional two-level inverters continue to be used for their simplicity and low cost, although they often underperform in demanding scenarios. Through systematic evaluation of these trade-offs, our study provides critical insights to assist engineers in selecting the most appropriate inverter topologies. This work not only serves as a detailed resource for practitioners but also identifies gaps and future research directions, thereby paving the way for more sustainable and efficient power conversion technologies.
Brushless dc motor (BLDCM) drives suffer inherently from high commutation torque ripple (CTR), which introduces speed fluctuation and torque pulsation, thereby affecting the smooth operation of the drive. To overcome this difficulty, BLDCM drive topologies supported by rectifier-fed dc–dc converters have gained great research attention because of their improved controllability and energy conversion capability. The nonlinear switching characteristics of the semiconductor devices distort the input current waveform leading to increased harmonics and reduced power factor. This necessitates higher RMS current drawn from the utility grid, resulting in elevated conduction losses and localized component heating, while creating difficulties in meeting international power quality standards. In this study, a front-end Zeta converter (FEZC)-fed BLDCM drive with integrated power factor correction (PFC) stage is proposed to address these limitations. The FEZC offers a regulated dc-link voltage (DCLV) that improves current commutation and significantly mitigates the CTR, while its inherent PFC capability shapes the input current to achieve near unity power factor (UPF) and low input current harmonics, therefore ensuring compliance with standards like IEC 61000-3-2 and IEEE 519. The suggested drive topology is validated through detailed analytical modeling, simulation, and experimental investigations. The obtained findings demonstrate improved conversion efficiency, lower total harmonic distortion (THD), and notable reduction in CTR.
