This paper proposes an 18-pulse star rectifier which uses two passive auxiliary injection circuits (PAICs) into the conventional double-star rectifier. The two PAICs consist of a modified tapped interphase reactor (MTIPR) with six diodes. The operation of the two PAICs increases both the output voltage and current states of each 3-pulse star rectifier, transforming the double-star rectifier into an 18-pulse star rectifier. This conversion reduces the total harmonic distortion (THD) of the input line current from 31.1% to 10.1%. The tap ratios of the MTIPR are selected based on the minimum THD of the input current. The MTIPR has a kVA rating of 8.95% of the load power, which is lower than that of other passive pulse-tripling IPRs used in double-star rectifiers, resulting in reduced magnetic rating and system cost. In addition, the voltage stress across the PAIC diodes is lower than that of existing pulse-tripling configurations for double star rectifiers. The validity of the theoretical analysis is confirmed through both simulation and experimental results. The measured input line current THD from the experimental setup is 5.98%. The proposed rectifier provides a cost-effective solution, making it suitable for high-current industrial applications.

In power system, increasing demand of green insulating fluids for transformer application has driven research works to biodegradable alternatives over conventional mineral based transformer oils. This experiment shows dielectric and physical performance of different types of vegetable oils, e.g. rice bran, soybean, mustard etc. and their binary mixtures focusing on the breakdown voltage (BDV), viscosity and pour point. It shows that rice bran oil expresses the highest BDV confirming its strong insulating capacity but limits its application in colder climate. Among different types of mixtures, soybean and mustard shows remarkable results. The performance was obtained by mixing soybean and mustard oil with the ratio of 75:25 resulted in high dielectric strength (32.8 kV/ 2.5 mm), low viscosity (48 cSt) in terms of natural oils, and notable pour point (-14°C) following the ASTM D97 standard. This study concludes that vegetable oils and their mixture can give sustainable environmental benefits featuring renewability, non-toxicity, and biodegradability while satisfying transformer fluid requirements across diverse conditions.

This paper proposes two types of passive auxiliary injection circuits (PAICs) that enable pulse tripling in three parallel-connected rectifiers, addressing the limitation of pulse multiplication to a factor of 2. The proposed design combined three rectifier units with two PAICs consisting of a delta/star transformer and nine auxiliary diodes. By further integrating the PAICs with conventional topologies such as 3-pulse star, 6-pulse star, 6-pulse bridge, 18-pulse star, and 18-pulse bridge rectifiers, we constructed 9-pulse star, 18-pulse star, 18-pulse bridge, 54-pulse star, and 54-pulse bridge configurations, respectively. The validation in MATLAB/Simulink demonstrated that these configurations achieved a threefold increase in both output-voltage pulses and input-current steps without the need for complex phase-shifting transformers. Moreover, the total harmonic distortion of the input current was significantly reduced, with values of 12.63%, 3.66%, 3.43%, 2.24%, and 1.90% for the respective designed rectifiers. To the best of our knowledge, this is the first demonstration of a passive pulse-tripling circuit for three parallel-connected rectifiers, offering a simple solution for high-current industrial applications.

A simple 12-pulse star rectifier using a new passive auxiliary injection circuit (PAIC) and a conventional double-star rectifier is proposed in this paper. The proposed PAIC consists of a modified extended interphase reactor (MEIPR) with four diodes, and the PAIC is installed at the DC link. Four diodes in the PAIC extract the rectangular-shaped current from the DC link and inject it into the load through MEIPR, which increase the levels of the output current and voltage of the double-star rectifier. These changes double the output voltage's pulse number and the input line current's step number. When the tap points in the MEIPR are placed in the proper positions, the PAIC transforms the six-pulse double-star rectifier into the 12-pulse star rectifier. The input line current THD value, determined from the experiment, is 8.09%. Four diodes in the PAIC are connected in parallel with the load, so the current stress and conduction loss are small, which means the proposed rectifier is suitable for low voltage and high current applications. A laboratory prototype has been constructed to experimentally validate the concept of the proposed 12-pulse star rectifier.

The growing demand for sustainable systems capable of serving three-phase loads from a single-phase grid has spurred significant research. Conventional DC-link-based single-phase to three-phase converters and variable frequency drives require massive and expensive processing units. Additionally, they have a high conduction loss as they involve multiple conversion stages. Similarly, traditional single-phase to three-phase cycloconverters suffer from excessive harmonic distortion in the output voltage and current. This article proposes a new single-phase to three-phase cycloconverter to reduce harmonics of the output voltage. This design employs a Specially-tapped Single-phase Transformer (STSPT), in which the secondary side of the transformer has 4 extra taps to create multiple voltage levels of sinusoidal pulses. These taps are placed according to calculations and simulations, which enabling frequency and phase conversion using only a single conversion stage with a reduced THD. Detailed analysis is presented, including its response to variable output frequency settings such as 16.67Hz, 12.5Hz, 10Hz, and 8.33Hz with resistive and motor loads. Multiple voltage levels of sinusoidal pulses in the output signal theoretically reduce the THD by up to 20% compared to conventional designs. A prototype of the cycloconverter was developed and the experimental results confirm close agreement with the theoretical predictions, demonstrating a THD reduction of up to 19% in the output voltage and current compared to conventional models, which makes it a reliable system to drive three-phase loads from a single-phase supply.

This article presents a novel 24-pulse rectifier with three new auxiliary circuits at the DC side to address the harmonic mitigation in input line currents, specifically for low-voltage and high-current applications. The proposed topology combines a double-star configuration with an integrated tapped interphase reactor (ITIPR) and its associated auxiliary circuits. These circuits reinject triangular currents from the ITIPR, improving the output voltage and current profiles while increasing the input current steps. The ITIPR and the auxiliary injection circuits transform the six-pulse rectifier into a 24-pulse rectifier, quadrupling the pulse count. The ITIPR’s tap ratios are optimized to minimize the total harmonic distortion (THD) of the input line current, achieving 7.71 % under optimal conditions. Unlike conventional 24-pulse rectifiers, the proposed design avoids additional input side transformers, making it compact, efficient, and cost-effective. It also features a simpler design with lower losses and fewer components. A 3 kW simulation prototype was developed and analyzed in MATLAB to validate the theoretical analysis.

This paper proposes a delta/fork transformer-based 30-pulse star rectifier for large current and low voltage applications. The proposed rectifier comprises two 15-pulse parallelly connected uncontrolled star rectifiers connected to the load through an inter-phase transformer (IPT). The Delta/fork type transformer is designed and optimized to produce two sets of 15-phase power supplies that supply the power to the two 15-pulse star-connected rectifiers. This analysis demonstrates that the proposed rectifier effectively suppresses up to the 29th-order harmonics from the input line current. Remarkably, the total harmonic distortion (THD) of both input line current and voltage remains below 5% even under varying load conditions. This research contributes to finding efficient power conversion and offers practical insights for industrial applications. The proposed rectifier finds its suitability in scenarios where isolation is essential. Notably, it serves applications such as aluminum potlines, traction substations, graphitizing furnaces, zinc electrolysis, and AC drives. Rigorous analysis, design, modeling, and MATLAB-based simulations validate the proposed design. The proposed rectifier meets the requirements of the IEEE-519 standards. This research contributes valuable insights into industrial power systems.

Dragon fruit is renowned for its nutritional value and economic potential, therefore accurately identifying fresh and diseased fruit and leaves is critical for preserving quality and optimizing production. The study leverages a dataset of 3,600 dragon fruit and leaf images from various developmental phases to build an automatic classification system. In this study, we evaluated raw images against the processed through a hybrid preprocessing pipeline that included CNNs such as VGG16, VGG19, DenseNet121, MobileNetV2, and Xception, alongside the Vision Transformer (ViT) model. The pipeline used Fourier Transform for noise reduction, CLAHE for contrast enhancement, and Sobel filters to detect diseased edges. Grad-CAM visuals helped to emphasize the crucial regions that influenced ViT's final decision. Although CNNs performed well, the ViT outperformed them, obtaining 94% accuracy on raw images and an outstanding 97.5% on preprocessed data, illustrating the pipeline's importance in improving feature extraction and overall accuracy.

Wheat is one of the worlds most significant cereals, with widespread adoption of modern cultivars. Early detection and technical treatment of crop diseases are crucial for reducing costs, protecting the environment, and ensuring food security by preventing crop losses and minimizing reliance on labor-intensive methods. While Convolutional Neural Networks (CNNs) have proven highly effective, they are limited to local convolution operations, restricting their ability to capture global and distant semantic connections. To enhance the diagnosis of brown rust, yellow rust, and healthy leaves, the authors employed multiple models, including VGG19, MobileNetV3, InceptionV3, DeiT, Swin Transformer, and ViT. The DeiT vision transformer model performed exceptionally well, achieving a 96.67% classification accuracy on an unseen dataset of 240 images. This result demonstrates the vision transformer based model's capability to accurately and effectively identify brown rust, yellow rust, and healthy leaves over CNNs.

Skin diseases happen to be the most common in the medical field, and they appear more visually than other disease groups. Researchers have noticed the great potential for applying computer vision techniques to diagnose skin disorders using image analysis. These disorders not only affect one's looks, but they can also lower one's self-esteem. Regular and comprehensive skin tests are essential for detecting any detrimental or developing changes that may lead to skin diseases. This study proposes a hybrid deep learning strategy that combines data-efficient image transformers (DeiT) with CNN-based models to accurately diagnose skin diseases, including psoriasis, in the early stages. The authors compared the effectiveness of four different algorithms-MobileNetV2, EfficientNetB7, VGG19, and DeiT to the proposed hybrid model, which combines DeiT, EfficientNetB7, and VGG19. Using a large dataset of skin diseases, the authors evaluated these models' performance using confusion matrices and other important performance metrics. Finally, the proposed hybrid model outperformed all other models with an impressive 97.25% accuracy, highlighting the benefits of merging transformer-based and CNN architectures.

Background: This study investigates the prevalence and characteristics of E. coli resistance patterns, focusing on isolates from patients with urinary tract infections (UTIs), diarrheal illnesses, and healthy controls. Methods: The study collected and identified E. coli isolates from 36 individuals: 17 with UTIs (urine samples), 6 with diarrhea (stool samples), and 13 healthy controls (stool samples). Antimicrobial susceptibility testing (AST) was performed to assess resistance against ten antibiotics from eight classes. Fluoroquinolone resistance was further evaluated against four drugs (nalidixic acid, ciprofloxacin, ofloxacin, and moxifloxacin). Additionally, molecular analysis of quinolone resistance-determining regions (QRDRs) in gyrA, gyrB, parC, and parE genes was performed on two selected isolates (U44 and U46) by genome sequencing. Results: Chloramphenicol and meropenem displayed the highest efficacy (>70% sensitivity), while AZM, AML, NA and SXT showed the highest resistance. UTI isolates exhibited higher resistance than diarrheal and healthy control counterparts. Worryingly, 58% of isolates exhibited multidrug resistance (MDR), with most (13/21) originating from UTI patients. The presence of MDR E. coli in five healthy individuals suggests potential carriage and community transmission. Fluoroquinolone resistance was particularly alarming, with moxifloxacin showing the highest resistance (80.95%). Molecular analysis confirmed mutations in all three fluoroquinolone resistance determining genes except gyrB. S84L and D87N dual mutations in the QRDR of gyrA was found in both isolates. S80I and S458A single mutations were observed in parC and parE, respectively. Conclusion: The study findings highlight the widespread prevalence of antibiotic resistance in E. coli and the urgent need for alternative treatment strategies. Bioresearch Commu. 10(2): 1532-1538, 2024 (July)

This research introduces a simple 18-pulse star rectifier, which is a combination of a conventional double-star rectifier and two new passive injection circuits. The proposed passive injection circuits are constituted with a specially tapped interphase transformer (STIPT) and four diodes. The proposed passive injection circuits can simultaneously increase the step number of the input line current and the pulse number of the load voltage. The first passive injection circuit (FPIC) doubles the pulse number of the traditional double-star rectifier converting it into an asymmetrical 12-pulse star rectifier while the second passive injection circuit (SPIC) further converts the 12-pulse star rectifier into 18-pulse star rectifier. For tripling the pulse number of the double-star rectifier, the STIPT requires to be designed optimally. For designing purpose, the proper tap ratios of the STIPT are determined depending on the minimum total harmonic distortion (THD) of the input line current. When designed optimally, the proposed rectifier simultaneously reduces the THD of the input line current and ripple of the output voltage with increasing pulses. In order to provide experimental validation for the theoretical evaluation, a laboratory prototype is constructed. The theoretical THD of the input line current is about 10.1%, whereas the experimental THD is about 5.42%.

Around the world, aloe vera is grown for both agricultural and therapeutic purposes, making it one of the most popular herbal treatments for topical skin diseases. Although aloe vera is unique in terms of providing nutrients and treating diseases, we fail to protect the leaves from bacteria, which significantly harms farms throughout the world. Identification of the foliar disease is critical because of the serious degree of damage. Aloe leaf infections were categorized using a number of deep learning methods, including VGG19, EfficientNetB5, EfficientNetB6, and EfficientNetB7. Using a smartphone camera, 2770 distinct images of aloe plants with two illnesses were included in the dataset (leaf spot and aloe rust). K-means clustering and histogram equalization were then used to preprocess the data. Finally, EfficientNetB7 outperformed the other experimented methods with a maximum accuracy of 94.11

Variable DC power supply units are widely used in the university laboratories to demonstrate different experiments to the engineering students. Mostly such power supply units are imported one, thereby expensive and cannot be repaired if gets out of order due to unavailability of spare parts and adequate servicing facilities. In this paper an indigenously developed DC power supply unit is presented. In this unit a TRIAC based ac voltage controller is used which provides the adjustable ac power at the input of a conventional bridge rectifier which converts the ac power to DC output. The novelty is that here a RC based modified triggering circuit is used to control the TRIAC. Thus variation of the output voltage over a wide range (0-300V) is possible. The design is such that the triggering circuit is very simple, uses a smaller number of components and it can be fabricated collecting all the parts from the local market. A prototype is made and tested in the laboratory using R, RL and motor load. The results are very satisfactory in accordance with the theoretical expectation.

Multidrug resistance (MDR) poses a global health threat, necessitating the exploration of alternative solutions. Probiotics, especially lactic acid bacteria (LAB), offer promising options against the impending crisis due to their recognized safety and potential health benefits. Probiotic potential characterization and selection of candidate LAB strains are highly crucial in probiotic product formulation. This study aimed to identify LAB from dairy product yogurt and evaluate their potential probiotic properties, i.e. aggregation capacity; tolerance to gastric and intestinal conditions; as well as antimicrobial potency. Ten LAB isolates were characterized based on colony characteristics, cellular morphology, and biochemical tests. The LAB isolates, both single and in mixed consortia, displayed a time-dependent increase in auto-aggregation, ranging from 21% to 71% after 5 hours of incubation. Isolate SW2 exhibited the highest auto-aggregative capability (65%). Co-aggregation studies revealed varying degrees of co-aggregation between probiotic LAB and pathogens, with some isolates showing stronger interactions (YD3, SW1, and SW2). Mixed consortia from sample TT demonstrated the highest co-aggregative ability with all tested pathogens. These findings highlight the potential of these isolates to form protective clusters, aiding in their survival and colonization within the gastrointestinal (GI) tract, besides the competitive exclusion of pathogens. The isolates demonstrated good tolerance to simulated gastric and intestinal conditions, as indicated by their non-significant reduction (only 1-2 log) in the bacterial count after 180 minutes of treatment. These findings indicate that LAB isolates can withstand harsh GI conditions, highlighting their suitability as probiotics. Antimicrobial profiles of the LAB isolates were evaluated using radial streak method and turbidimetric microtiter plate assay against eight MDR diarrheal and Uro-pathogens (n=4 for each). LAB isolates SKY1, SW1, SW3 and TT1 exhibited the highest antimicrobial activities; while pathogens DP2, UP41 and UP42 showed the most sensitivity. Exhibited antimicrobial activity of the LAB isolates points to their potential as formidable weapons against MDR infections. Overall, the results indicate that dairy-derived LAB isolates used in this study exhibit potential probiotic traits. Further research is warranted for their mechanisms, safety, efficacy, and use in probiotic supplement development. Bioresearch Commu. 9(2): 1340-1350, 2023 (July)

South Asian cuisines encompasses a rich variety of traditional fermented foods, which hold great promise as sources of probiotic bacteria with notable health benefits. This study aimed to isolate and characterize probiotic strains from homemade plant-based fermented foods (kanji drink and rice kanji) and commercial dairy-based probiotics (sweetened and probiotic yogurt). The samples were found safe for consumption, devoid of indicator microorganisms and hemolytic activity. They exhibited a diverse microflora with substantial microbial counts (>106 CFU/ml), identified as yeasts and lactic acid bacteria (LAB) namely Lactobacillus curvatus, Leuconostoc mesenteroids, Lactobacillus delbrueckii ssp lactis, Lactobacillus plantarum, and Lactobacillus delbrueckii. Antimicrobial activity tests against six foodborne pathogens demonstrated significant reductions in their growth, highlighting the broad-spectrum antimicrobial potential of the probiotic isolates against gram-positive and gramnegative bacteria. The mixed consortium of samples showed higher growth inhibition compared to individual isolates, emphasizing the importance of microbial diversity in probiotic formulations. The samples' mix consortiums also displayed high auto-aggregative (42.36%-75%) and co-aggregative abilities (up to 93%) with the pathogens over time, with sweetened yogurt showing the highest co-aggregation percentage. The antimicrobial activity of the mix consortiums correlated positively with auto-aggregative capability but negatively with coaggregative capability, although these correlations were not statistically significant. Consumer acceptance tests, using a nine-point hedonic scaling, favored commercial yogurts over homemade kanji, with sweetened yogurt receiving the highest scores. In conclusion, this study provides insights into the safety, quality, microbial characteristics, antimicrobial activity, aggregative capability, and consumer acceptance of both commercial yogurt and homemade kanji. Considering the limitations of dairy-based probiotics and the growing popularity of vegetarian diets, promoting the consumption of homemade plant-based fermented foods like kanji, which offer wholesome nutrition and potential probiotic benefits, is recommended. Future research should focus on characterizing the in-vivo probiotic potential and standardizing formulations based on consumer demands.

Cabbage diseases such as black rot, downy mildew, and white rust are frequent and have a negative impact on yield. However, existing research lacks an accurate and rapid detector of cabbage diseases to assure healthy cabbage production. In this research, the transfer learning approach has been employed for many state-of-the-art CNN architectures, such as VGG16, VGG19, mobilnetv2, and InceptionV3, to determine the most optimal solution for this problem. A dataset of around 1500 images from three different classes is employed to train and validate the models. Among the multiple CNN models evaluated, vgg16 produced 95.55% test accuracy, which is far superior to other similar experiments conducted recently.

Power transformers are the key components of modern power system network. Oil is used in a transformer for insulation and cooling purpose. As transformer undergoes electrical, thermal, and chemical distress throughout their lifetime, the oil deteriorates. In the present research, the breakdown voltage of newly purchased transformer oil and old oil, collected from a transformer serving for 10 years, has been investigated through laboratory experiments. Two types of electrode pairs, plane-plane (uniform field) and point-plane (non-uniform field) have been used to observe the behavior of both insulating samples under uniform (theoretical) and non-uniform (real life) field situation. An interesting observation is the continuous flow of current through the old oil sample for non-uniform field condition; which may cause the rise of temperature of the oil as well as the transformer; thus the old transformer is at high risk of fire hazard. As expected the breakdown strength of new oil under uniform field is found to be higher than that of the old oil under non-uniform field condition.

Bangladesh is experiencing a second wave of COVID-19 since March 2021, despite the nationwide vaccination drive with ChAdOx1 (Oxford-AstraZeneca) vaccine from early February 2021. Here, we characterized 19 nasopharyngeal swab (NPS) samples from COVID-19 suspect patients using genomic and metagenomic approaches. Screening for SARS-CoV-2 by reverse transcriptase polymerase chain reaction and metagenomic sequencing revealed 17 samples of COVID-19 positive (vaccinated = 10, nonvaccinated = 7) and 2 samples of COVID-19 negative. We did not find any significant correlation between associated factors including vaccination status, age or sex of the patients, diversity or abundance of the coinfected organisms/pathogens, and the abundance of SARS-CoV-2. Though the first wave of the pandemic was dominated by clade 20B, Beta, V2 (South African variant) dominated the second wave (January 2021 to May 2021), while the third wave (May 2021 to September 2021) was responsible for Delta variants of the epidemic in Bangladesh including both vaccinated and unvaccinated infections. Noteworthily, the receptor binding domain (RBD) region of S protein of all the isolates harbored similar substitutions including K417N, E484K, and N501Y that signify the Beta, while D614G, D215G, D80A, A67V, L18F, and A701V substitutions were commonly found in the non-RBD region of Spike proteins. ORF7b and ORF3a genes underwent a positive selection (dN/dS ratio 1.77 and 1.24, respectively), while the overall S protein of the Bangladeshi SARS-CoV-2 isolates underwent negative selection pressure (dN/dS = 0.621). Furthermore, we found different bacterial coinfections like Streptococcus agalactiae, Neisseria meningitidis, Elizabethkingia anophelis, Stenotrophomonas maltophilia, Klebsiella pneumoniae, and Pseudomonas plecoglossicida, expressing a number of antibiotic resistance genes such as tetA and tetM. Overall, this approach provides valuable insights on the SARS-CoV-2 genomes and microbiome composition from both vaccinated and nonvaccinated patients in Bangladesh.

Selection criteria is very crucial to pick up promising genotypes in a breeding program. An experiment was conducted with twenty soybean genotypes following a randomized complete block design to study the inheritable agronomic traits, their interrelation and partitioning of genotypic correlation into direct and indirect effects to identify the traits responsible for higher seed yield. Results indicated that phenotypic variance was higher than that of genotypic variance for all the characters. The highest PCV was found for the trait seed yield per plant (39.03%) followed by yield per plot (32.85%). The higher GCV was also found for the same traits- seed yield per plant (37.36%), yield per plot (27.23%). PCV and GCV was the lowest for trait days to maturity (6.28%, 4.16%) and days to flowering (3.20%, 2.24%). Estimated broad sense heritability was ranged from days to flowering (44.05%) to seed yield per plant (91.62%). Higher estimate of heritability was also observed for yield per plot (88.65%) followed by hundred seed weight (85.39%) whereas; heritability was moderate for plant height (76.75%) and pod per plant (70.17%). The genetic advance was the highest for plant height (19.39%). On the other hand, primary branch per plant, days to flowering and days to maturity showed low heritability with low GA depicts the influence of non-additive gene effect. Pod per plant, hundred seed weight, days to maturity and plant height is positively and significantly correlated with yield. Pod per plant (0.908) and hundred seed weight (0.907) showed highest direct positive effect on seed yield at genotypic level. Path analysis also confirmed highest positive direct effect of hundred seed weight (0.701). So, the present study suggests that, higher hundred seed weight and pod per plant can be effective selection measure for improvement of soybean yield.