IJEM Vol. 12, No. 5, Oct. 2022
Cover page and Table of Contents: PDF (size: 543KB)
The significance of electricity access to man's socioeconomic development cannot be overstated. putting competing demands on limited resources. Electrification as one of the demands requires efficient use of these scarce resources using appropriate electrification plans that would improve the attractiveness of policymakers to electrification which in turn brings the development to rural and extending communities. There is a need for a rural-electrification planning structure that considers social equity and balanced regional development through the most cost-effective investment options delivering a reasonable level of service. The objectives of the study were to compare two electrification plans including extending the existing grid distribution system and implementing renewable energy-based rural electrification (RE) for two dissimilar communities. Grid extension, which has a lower initial installation cost and is a suitable option where there are commercial and industrial consumers, is the most economically feasible electrification plan for a community that is close to the existing power grid or one that is growing, according to the study's findings. However, results of the study also show that off-grid electrification model is more cost-effective than a grid extension for electrifying far-from-the-grid un-electrified areas. This model has a higher functional value, economic value, and suitability for remote communities because these areas have fewer infrastructures and off-grid systems are typically designed for basic lighting and residential applications.[...] Read more.
A wafer map depicts the location of each die on the wafer and indicates whether it is a Product, Secondary Silicon, or Reject. Detecting defects in Wafer Maps is crucial in order to ensure the integrity of the chips processed in the wafer, as any defect can cause anomalies thus decreasing the overall yield. With the current advances in anomaly detection using various Computer Vision Techniques, Transformer Architecture based Vision models are a prime candidate for identifying wafer defects. In this paper, the performance of Four such Transformer based models – BEiT (BERT Pre-Training of Image Transformers), FNet (Fourier Network), ViT (Vision Transformer) and Swin Transformer (Shifted Window based Transformer) in wafer map defect classification are discussed. Each of these models were individually trained, tested and evaluated with the “MixedWM38” dataset obtained from the online platform, Kaggle. During evaluation, it has been observed that the overall accuracy of the Swin Transformer Network algorithm is the highest, at 97.47%, followed closely by Vision Transformer at 96.77%. The average Recall of Swin Transformer is also 97.54%, which indicates an extremely low encounter of false negatives (24600 ppm) in contrast to true positives, making it less likely to expose defective products in the market.[...] Read more.
Flapping wing micro-air-vehicles (FWMAV) are micro-air-vehicles that use biomimetic actuation (oscillatory flapping wing) for aerodynamic force generation. The realization of such bionic flight, which offers small size, low speed, and flexible maneuverability has significant military and civilian values. Thus the design of FWMAV (ESB-I) will be very important for security related sectors since they have all the right stuffs for surveillance and reconnaissance. Since everything about a bird is made for flight the kinematic and dynamic modeling as well as control algorithm of bird like FWMAVs is more complex than that of serial robots. Thus balancing the main requirements for the design of FWMAVs which includes excellent aerodynamic performance, high efficiency, and satisfactory maneuverability is very important. With the aim to improve the performance of a FWMAV this work incorporates an intermittent flapping and gliding flight mode. Flap-gliding flight mode, which is often used by large bird species, effectively combines the aerodynamic advantages of fixed and flapping wings. Inspired from it, a kind of flexible flap-gliding Micro Air Vehicle, named Ethio-Smart Bird-I (ESB-I), was successfully designed. An expression describing the mechanical energy cost of travelling of this flight mode in terms of work per range for one flap-glide flight cycle was presented. It is shown that there is an energy saving of flap-gliding flight compared to continuous flapping flight. However due to a system dynamic variation in this flight mode, it possesses difficulty in control surface design. To implement this specific flight mode, this thesis proposes a closed-loop active disturbance rejection control, ADRC, strategy to stabilize the attitude during the processes of flapping flight, transition and gliding flight. To verify the control effect, the unsteady aerodynamic estimation method of the flapping wing based on modified strip theory approach and the dynamics of the FWMAV in Lagrangian form were modelled in the MATLAB/SIMULINK platform and applied in the simulation. Using this model longitudinal stability of ESB-I was analyzed. Simulation results show that even if the FWMAV is in different flight modes, ADRC controller can track the target pitch signal effectively with tracking error less than 0.05rad. To further explain the effects of ADRC in this specific flight mode, the control effects of a PID controller is presented. As per the simulation result ESB-I with PID controller has a target pitch angle tracking error greater than 1rad. This shows that, in flap-gliding flight mode ADRC can track the target pitch signal better than PID controller.[...] Read more.
Insophisticated situations coming from developing multimedia applications and the exponential increase in the number of smart sensors and devices, future wireless networks will ensure high reliability, low latency, scalability, as well as better quality-of-service.Optical wireless communication (OWC) becomes more important because it can take advantage of the light medium's unique selling points over RF, such as immunity to electromagnetic interference (EMI), ultra-high capacity, the ability to communicate wirelessly through water, and the ability to provide additional security. Dual polarization (DP) enabled multilevel modulations in inter satellite optical wireless communication (Is-OWC) are potential and capacity building techniques to cope up with bandwidth explosive demands. Therefore, inthis work, a reach enhanced single channel Is-OWC is proposed using Double Sideband Suppressed (DSS) dual polarized (DP) Quadrature phase shift keying (QPSK) modulation. Spectral efficiency of carrier is improved through DSS technique using Mach-Zehndar modulator (MZM) and millimeter wave (mm- wave). Further, pulse width reduction, nonlinear effects suppression, carrier phase estimation (CPE) and frequency offset estimation (FPE) is performed by Digital signal processor (DSP) in coherent receiver of PDM-QPSK. Performance comparison of DP-QPSK and DSS-DP-QPSK is performed at different link lengths in terms of log BER and error vector magnitude (EVM%). Results revealed that proposed system i.e., DSS-DP-QPSK at 160 Gbps data rate covers 44,000 km Is-OWC distance with acceptable log BER as compared to 40,000 km in DP-QPSK due to improved spectral efficiency of carrier spectrum of proposed system.[...] Read more.
Leakage of gas is a major issue in the industrial sector, residential buildings, and gas-powered vehicles, one of the preventive methods to stop accidents associated with gas leakage is to install gas leakage detection devices. The focus of this work is to propose a device that can detect gas leakage and alert the owners to avert problems due to gas leakages. The system is based on a microcontroller that employs a gas sensor as well as a GSM module, an LCD display, and a buzzer. The system was designed for gas leakage monitoring and alerts with SMS via an Arduino microcontroller with a buzzer and an MQ2 gas sensor. The circuit contains a Microcontroller MQ2 gas sensor, buzzer, LCD display, and GSM module, when the sensor detects gas leakage it transmit the information to the Microcontroller while the microcontroller makes a decision and then forwarded a warning message to the user as SMS to a mobile phone for decision to be taken accordingly. The output of this research will be significant in averting problems associated with gas leakages now and in future.[...] Read more.