SJEE

A Search for Suitable Mother Wavelet in Discrete Wavelet Transform Based Analysis of Acoustic Emission Partial Discharge Signals

2024-07-19T13:39:22+00:00

Signal processing helps monitor the condition of power equipment. Partial discharge (PD) signals used in condition-based maintenance give crucial information in the diagnosis of degradation of insulation. The acoustic emission technique (AET) is one of the most widely used techniques in PD signal analysis due to its inherent advantages. Analyzing acoustic emission partial discharge (AEPD) signals in the wavelet-domain provides critical insights into the location and type of the sources of PD. Selection of the most suitable mother wavelet in applying discrete wavelet transform (DWT) on AEPD signals is important as it will directly impact the outcome. For this selection, 36 wavelets belonging to the Daubechies, Symlets, Coiflets, and Bi-orthogonal families are investigated. For this purpose, five experimentally collected AEPD test signals are used. The selection is based on the “accuracy of wavelet decomposition results” in this work, probably for the first time. One mother wavelet from each family is individually shortlisted for all three performances, namely (a) reconstruction, (b) denoising, and (c) compression, by computing and comparing their commonly used metrics. Further, based on percentage energy criteria, the most suitable mother wavelets are identified as coif3, coif4, and coif5, respectively, for the three performances.

Improved Cuckoo Search Optimization for Production Inventory Control Systems

2024-07-16T17:20:48+00:00

In the industry, the efficient use of production-inventory control system has a great importance. This article presents an investigation study of the impact of an optimal Integral minus Proportional Derivative (I-PD) controller on the dynamic behavior of production-inventory system. The differential equations of the system are firstly formulated. Then, the I-PD controller is proposed to enhance the responsiveness of the inventory performance. Two swarm optimization techniques, Cuckoo Search Optimization (CSO) and an Improved CSO (ICSO), are applied to optimally tune the design parameters of the proposed I-PD controller. In order to represent a realistic environment, two simulations are conducted. The first scenario is conducted when the production-inventory system is subject to a unit step change in the desired input, while the second scenario has demonstrated the behaviors of system under random demand input. The simulation results based on MATLAB programming software showed the superiority of ICSO to tune the I-PD controller over the traditional CSO. In comparison study of performance for both tuning schemes, the Integral Time of Absolute Error (ITAE) index has been used as a measure of assessment. As compared to traditional CSO, the result indicates that the I-PD tuned by ICSO could better improve the performance of production-inventory system in terms of significant reduction in inventory cost.

A Compact High Gain UWB Planar Monopole Antenna Using Circular Slots

2024-07-16T17:20:51+00:00

In this manuscript, the design of a compact-size circular patch UltraWideband (UWB) antenna with enhanced fractional bandwidth (BW), peak realized gain (PRG), and proper impedance matching is presented. The modified antenna has three circular slots etched from the circular path (top), fed by a 50Ω microstrip feed line. These circular slots play a significant role in improving the impedance bandwidth. Additionally, the partial ground plane with a slot integrated with a rectangular stub is used in order to achieve a bandwidth for an operating range of 3.25 GHz – 27 GHz. The proposed antenna is designed, fabricated, and tested in the laboratory in order to validate with simulation data. The designed antenna size is 25 mm  20 mm × 0.508 mm. The experimental value of 10 dB return loss absolute/fractional BW of 23.75 GHz/157.08% at the center frequency, minimum/ maximum gain of 5.90/12.05 dBi, and maximum /minimum radiation efficiency of 85/97 % are achieved from the 3.25 GHz to 27 GHz frequency range. In addition, a comparison table is provided to prove the state-of-the-art of the antenna’s design. The proposed antenna is suitable for wireless services, radar, and satellite communication.

An Analysis of Cache Configuration’s Impacts on the Miss Rate of Big Data Applications Using Gem5

2024-07-17T09:41:46+00:00

This work aims to analyze the impacts of cache configurations on miss rates of big data benchmarks with varying level 1 instruction (L1I) and data (L1D) caches using the gem5 simulator. The cache miss rate of nine big data applications from four benchmark suits is analyzed with different cache configurations, such as increasing the cache size, varying the associativity, and altering the line size. The gem5 provides a versatile platform for conducting detailed experiments. The study sheds light on the relationship between cache and big data workloads, thus offering insights into optimizing cache configurations’ effect on miss rates for improved performance.

A Proactive Controller Failure Recovery Mechanism in SD-WAN with Multiple Controllers

2024-07-16T17:20:59+00:00

The separation of data and control plane is a key feature of Softwaredefined networking (SDN), which makes network administration more intelligent. The control plane is realized using a logically centralized controller. In SD-WAN, as the network becomes larger, multiple controllers are needed to manage the network. In this scenario, there is a chance for controller failure due to overload. Once the controller fails, the switches lose connection with the controller. The load of the failed controller is to be re-distributed among other controllers. Sometimes this load transfer may cause many other problems like controller chain failure. It may consistently undermine the trustworthiness of the network. In the proposed technique, the multiple controller deployment based on affinity propagation clustering in SD-WAN is extended to include a proactive controller failure recovery mechanism. Whenever the controller load exceeds a pre-defined threshold, a set of switches under the bottleneck controller will be reassigned to a neighbouring controller without exceeding its capacity. The simulation results show that when network traffic increased, the proposed proactive controller failure recovery method balanced the controller load, resolved a cascading controller failure, improved the average throughput, and reduced the average end-to-end delay and packet loss effectively.

Wavelet Transform Generated Inherent Noise Reference for Adaptive Filtering to De-noise Pulse Oximeter Signals

2024-07-16T17:30:26+00:00

As exemplified during the COVID-19 pandemic and in post-operative intensive care units, monitoring blood oxygen saturation (SpO₂) levels is crucial in terms of assessing a patient’s health condition. Due to random movements of the subject, a pulse-oximeter-driven photoplethysmographic (PPG) signal becomes noisy while recording, with motion artefacts (MAs), which will disturb the morphological features, leading to incorrect SpO₂ levels. The MA noise may contain either low- or high-frequency components, resulting in a scenario with inband and out-of-band noise. The reduction of in-band noise with an adaptive filter requires a reference signal, and an additional sensor such as an accelerometer is normally used in addition to the PPG sensor to capture the MAs. The present work focuses on the generation of a reference for inherent noise using a wavelet transform (WT), thereby eliminating the need for an external sensor. The computed values of the correlation coefficient and magnitude squared coherence are used to establish the validity of the generated inherent noise reference. Our WT-driven adaptive filtering method reduces MAs, simplifies the correct approximation of the SpO2 and heart rate, and also restores the respiratory components. The de-noised PPG signals presented here and a corresponding numerical study prove the usefulness of the proposed method, which has a worst-case accuracy of 0.5% in regard to SpO₂ estimations.

Optimizing DC and RF Characteristics of Pseudomorphic AlGaN/InGaN/GaN HEMT for GHz Application

2024-07-16T17:21:07+00:00

This paper presents a design and in-depth analysis of DC and RF characteristics of Pseudomorphic AlGaN/InGaN/GaN High Electron Mobility Transistor (HEMT) for microwave application. Experimental data from an AlGaN/InGaN/GaN HEMT is used to validate the simulation results based on the Id-Vg curve and transconductance, demonstrating their close agreement. Subsequently, the study focuses on investigating the impact of varying device parameters namely Indium (In) proportion of InGaN, gate length, source to gate length (Lsg) and gate to drain length (Lgd), and InGaN layer thickness. Sequential analysis has been done for various device parameters as a function of frequency. The results indicate that the device exhibits optimal performance when configured with an Indium (In) proportion of 0.15, a gate length of 0.40 μm, an InGaN layer thickness of 2 nm and L_sg and L_gd of 1.15 μm, and 1.15 μm respectively shows ft 15.36 GHz and f_max 37 GHz which is almost more than twice of the original calibrated device. These findings provide valuable insights for designing devices with enhanced performance.