Volume 10, issue 1

A lightning detection system based on a large-diameter Rogowski coil and an analog integrator was developed for wind turbine applications and is presented in this paper. To accurately detect lightning current, the Rogowski coil was designed with a lower cutoff frequency of 0.1 Hz. The analog integrator, comprising an inverting active integrator, and an amplifier, was used to restore the original waveform of the lightning current. Tests were conducted to verify the bandwidth of the system using alternating current, damped sinusoidal current, and a rectangular pulse. The system demonstrated a bandwidth of 0.1 Hz to 100 kHz, which is within the standard acceptable range. This lightning detection system offers a significantly lower cost compared to commercial alternatives, making it highly suitable for practical applications.

Extemporaneous omeprazole-based preparations are commonly used in hospitals; however, there are no validated studies about physicochemical stability. This study aimed to determine if temperature, luminosity, and the type of diluent affect the stability of omeprazole in the extemporaneous preparation. For stability, the methodology validated previously by our group was used. The 2k experimental design included Temperature (25ºC and 35ºC) and Luminosity (covered by light and 400 Lx) variables. Diluents were evaluated at five levels: 1) Citric acid + polyethylene glycol solution, 2) Polyethylene glycol solution, 3) Physiological saline solution, 4) Citric acid + polyethylene glycol solution + physiological saline solution, and 5) Polyethylene glycol solution + physiological saline solution. Minitab 18 software was used for data analysis, and the degradation kinetics were determined by linear regression. The optimal condition for physicochemical stability was a temperature of 25ºC covered by light (OM1-3h 49’, OM2-3h 2’, SSF-5h 8’, OM1SSF-2h 27’, OM2SSF-6h 23’). The diluent based on physiological saline solution provided more than five hours of shelf-life, and more than six hours, the diluent based on OM2 + SSF. However, the best option is physiological saline solution, considering the accessibility of the diluent. In conclusion, environmental conditions should be considered in extemporaneous omeprazole-based preparation since they are affected by temperature, luminosity, and type of diluent. Assessing shelf-life prior to administration is necessary to provide a safe and effective drug, avoiding the occurrence of side effects in patients.

The rapid expansion of digital universities across Africa addresses the need for scalable higher education solutions, but challenges such as limited physical infrastructure and high dropout rates persist. In digital learning environments, effective interaction with educational content is crucial for student success. This article explores the transformative role of chatbots integrated into digital university platforms, with a specific focus on their impact on learner-content interactions. Leveraging the frequent use of messaging applications and advances in Artificial Intelligence (AI), we examine how chatbot integration enhances student engagement, facilitates personalized access to core educational modules, and supports formative assessments to reinforce learning outcomes. Using the Rasa open-source framework and the Moodle Learning Management System (LMS), we present a model that not only delivers content efficiently but also provides an interactive learning experience through AI-driven dialogue systems. Furthermore, a comparison of the different AI tools used for educational chatbots will be presented, to determine the most suitable solutions for digital teaching. This analysis will consider various aspects such as efficiency, customization, flexibility and ease of integration of the tools into educational environments. This study highlights how chatbots can foster a more dynamic and responsive learning ecosystem, ultimately improving student retention and mastery of key concepts in digital universities. In this article, we explore the broader impact of chatbots on learner interaction with educational content, not just their integration. It also emphasizes student engagement and retention.

Skewing of the rotor slot of a squirrel-cage induction machine has been commonly used since the beginning. However, little guidance is given regarding the principle of the working effect of the method, but even in such rare cases, the explanation does not cover the true physical reality. Consequently no formula exists for calculation of the effect. In this study, the principle of the working effect of the rotor’s skewing is derived in accordance with the true physics of the phenomenon, for both the synchronous and the asynchronous parasitic torque. The calculation regarding synchronous parasitic torque is based on comparing the stepped MMF curve of the straight rotor slot and the trapezoidal MMF curve of the skewed slot. New formulas are provided for both type of parasitic torques. Practical cases are investigated in details. Knowing the theory and the formula of slot skewing, the skew can now be applied on a targeted manner and in some cases, can completely eliminate the dangerous torque and noise components. Consequently, a theorem is formulated on when to skew according to the stator and when acc. to the rotor slot pitch; another theorem was found regarding residual synchronous parasitic torque after skewing. The investigation is then extended to include differential leakage attenuation calculations. With this in mind, from the point of view of rotor slot skew, the topic has been reviewed in its entirety.

Despite the development of the Internet and wired networks such as fiber optics, mobile networks remain the most used thanks to the mobility they offer to the user. However, data protection in these networks is more complex because of the radio channels they use for transmission. Hence,there is a need to find more sophisticated data protection means to face any attack. But, this is not an easy task, especially with the emergence of AI-based attacks. In this context, we proposed in this work a solution that can significantly improve data protection in a new-generation mobile network. Therefore, the main objective of this study is to improve and implement an enhanced version of the standard ZUC algorithm designed by the Data Assurance and Communication Security Research Center of the Chinese Academy of Sciences and standardized by the 3GPP (3rd Generation Partnership Project) organization to ensure the LTE (Long Term Evolution of radio networks) security. The proposed design is principally based on replacing the static Sboxes of the original algorithm (S 0 and S 1) with a chaos-based dynamic S-boxes thus allowing to generate a different key stream for any change on the secret key and with the best randomness and robustness properties. The two new dynamic S-boxes are initialized with 256 initialization values each (x”00”), then filled in parallel using two chaotic maps that use the ZUC algorithm registers, the CK (Cipher Key), and the IV (Initial Vector) to form two different initial values for each chaotic map. To reach the hardware performance, we implemented the system on a Xilinx XC7Z020 PYNQ-Z2 FPGA platform. The designed architecture occupies low logic resources (1135 Slice LUTs, 762 Slice Registers, and 8 DSP48E1) on the used FPGA device and can reach a throughput of 2515.84 Mbps with a running frequency of 78.62 Mhz by consuming only 0.188 W. To evaluate the resistance of the proposed cryptosystem, we used many security tests (keystream distribution, keystream randomness, key sensitivity, plaintext sensitivity, keyspace, and NIST statistical tests). The experimental results and comparison with other S-boxes based algorithms prove on one hand that using the dynamic S-box technique has enforced considerable data protection against cryptanalysis attacks, and on another that the hardware metrics (used logic resources, achieved throughput, and efficiency) are suitable for real-time applications such as mobile security transmission.

Text line segmentation from document images is a significant challenge in the field of document image analysis. It involves extracting individual text lines from Myanmar handwritten document images to enable text recognition. This task becomes particularly challenging in Myanmar handwritten documents, especially those with irregular or cursive writing styles, due to variations in line spacing, and touching and overlapping characters in Myanmar handwritten documents. This paper proposes a text line extraction method based on an average linkage clustering algorithm for handwritten document images to address segmentation errors caused by characters with inconsistent spacing, different writing styles, and line overlaps due to ascenders and descenders. In this paper, Connected Components (CCs) are extracted by using Connected Component Analysis (CCA) and Anisotropic Gaussian multiscale technique. And then convex-hull computation based on the divide and conquer method is used to re-segment the irregular touching components. Then the text lines are extracted by the proposed system based on an average linkage clustering algorithm that consider both the smaller and larger within-cluster variance. The performance of the proposed method is evaluated using the Pixel and Line Intersection over Union (IU) values, which are found to be 93.27% of Pixel IU and 95.09% of Line IU on dataset 1 and 92.61% of Pixel IU and 89.90% of Line IU on dataset II, respectively. According to the experimental results based on the existing dataset and their own data set, the proposed system can give a better result than the Density-Based Spatial Clustering and Application with Noise (DBSCAN) clustering algorithm.

With the spread of inverters, the attention of designers naturally turned to 5-phase motors, due to their advantageous properties. In this regard, perhaps the most important issue in the design of such machines is the selection of the correct rotor slot number. Many articles have been published on multiphase machines, however, only few of them deal with the rotor slot number. Although very useful results are achieved, the result is not comprehensive, systematic approach still awaits. In this paper, the behavior of the full range of 3-phase machines is calculated by using our formulas developed before, and then the method is simply transferred to 5-phase. The point is that relative rotor slot numbers are applied therefore the results are valid for any pole number on a comprehensive way. Detailed, well established design rules are provided. For better understanding of the process, the behavior of the oscillating torques generated by the synchronous parasitic torques during run-up and operation will be presented, using the equations of the unified electric machine theory. During the noise calculation, the concept of the Noise Component Equivalence Measure is introduced, which enables an accurate comparative calculation of the spectra of the radial force waves that excite the noise; it provides the final, comprehensive criteria for the selection of the right rotor slot number. With the study, the entire range of the slot number of any rotor mounted in any stator with any number of poles and number of slots is covered.