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A Single-Phase Cell-Based Asymmetrical Cascaded Multilevel Inverter
Singh, Varsha,Pattnaik, Swapnajit,Gupta, Shubhrata,Santosh, Bokam The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2
A single-phase asymmetrical cascaded multilevel inverter is introduced with the goal of increasing power quality with the reduction of power in insulated-gate bipolar transistor (IGBT) switches. In the present work, the proposed inverter topology is analyzed and generalized with respect to different proposed algorithms for choosing different voltage source values. To prove the advantages of the proposed inverter, a case study involving a 17-level inverter is conducted. The simulation and experimental results with reduced THD are also presented and compared with the MATLAB/SIMULINK simulation results. Finally, the proposed topology is compared with different multilevel inverter topologies available in the literature in terms of the number of IGBT switches required with respect to the number of levels generated in the output of inverter topologies.
A Single-Phase Cell-Based Asymmetrical Cascaded Multilevel Inverter
Varsha Singh,Swapnajit Pattnaik,Shubhrata Gupta,Bokam Santosh 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2
A single-phase asymmetrical cascaded multilevel inverter is introduced with the goal of increasing power quality with the reduction of power in insulated-gate bipolar transistor (IGBT) switches. In the present work, the proposed inverter topology is analyzed and generalized with respect to different proposed algorithms for choosing different voltage source values. To prove the advantages of the proposed inverter, a case study involving a 17-level inverter is conducted. The simulation and experimental results with reduced THD are also presented and compared with the MATLAB/SIMULINK simulation results. Finally, the proposed topology is compared with different multilevel inverter topologies available in the literature in terms of the number of IGBT switches required with respect to the number of levels generated in the output of inverter topologies.
COUPLED FIXED POINT THEOREMS FOR RATIONAL INEQUALITY IN GENERALIZED METRIC SPACES
Singh, Deepak,Tomar, Surjeet Singh,Rathore, M.S.,Chauhan, Varsha The Youngnam Mathematical Society 2015 East Asian mathematical journal Vol.31 No.1
In modern times, coupled fixed point theorems have been rigorously studied by many researchers in the milieu of partially ordered G-metric spaces using different contractive conditions. In this note, some coupled fixed point theorems using mixed monotone property in partially ordered G-metric spaces are obtained. Furthermore some theorems by omitting the completeness on the space and continuity conditions on function, are obtained. Our results partially generalize some existing results in the present literature. To exemplify our results and to distinguish them from the existing ones, we equip the article with suitable examples.
Coupled fixed point theorems for rational inequality in generalized metric spaces
Deepak Singh,Surjeet Singh Tomar,M.S.Rathore,Varsha Chauhan 영남수학회 2015 East Asian mathematical journal Vol.31 No.1
In modern times, coupled fixed point theorems have been rigorously studied by many researchers in the milieu of partially ordered G- metric spaces using different contractive conditions. In this note, some coupled fixed point theorems using mixed monotone property in partially ordered G-metric spaces are obtained. Furthermore some theorems by omitting the completeness on the space and continuity conditions on function, are obtained. Our results partially generalize some existing results in the present literature. To exemplify our results and to distinguish them from the existing ones, we equip the article with suitable examples.
Correlation of TTF-1 immunoexpression and EGFR mutation spectrum in non–small cell lung carcinoma
Tripti Nakra,Varsha Singh,Aruna Nambirajan,Prabhat Singh Malik,Anant Mohan,Deepali Jain 대한병리학회 2021 Journal of Pathology and Translational Medicine Vol.55 No.4
Background: Thyroid transcription factor (TTF-1) is a diagnostic marker expressed in 75%–85% of primary lung adenocarcinomas (ACs). Activating mutations in the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) gene is the most common targetable driver alteration in lung AC. Previous studies have shown a positive correlation between TTF-1 and EGFR mutation status. We aimed to determine the predictive value of TTF-1 immunoexpression for underlying EGFR mutation status in a large Indian cohort. Methods: This retrospective designed study was conducted with medical record data from 2011 to 2020. All cases of primary lung AC and non–small cell lung carcinoma not otherwise specified (NSCLC, NOS) with known TTF-1 expression diagnosed by immunohistochemistry using 8G7G3/1 antibodies and EGFR mutation status diagnosed by quantitative polymerase chain reaction were retrieved, reviewed, and theresults were analyzed. Results: Among 909 patient samples diagnosed as lung AC and NSCLC, NOS, TTF-1 was positive in 76.8% cases (698/909) and EGFR mutations were detected in 29.6% (269/909). A strong positive correlation was present between TTF-1 positivity and EGFR mutation status (odds ratio, 3.61; p < .001), with TTF-1 positivity showing high sensitivity (90%) and negative predictive value (87%) for EGFR mutation. TTF-1 immunoexpression did not show significant correlation with uncommon/dual EGFR mutations (odds ratio, 1.69; p = .098). EGFR–tyrosine kinase inhibitor therapy was significantly superior to chemotherapy among EGFR mutant cases irrespective of TTF-1 status; however, no significant differences among survival outcomes were observed. Conclusions: Our study confirms a strong positive correlation between TTF-1 expression and common EGFR mutations (exon 19 deletion and exon 21 L858R) in advanced lung AC with significantly high negative predictive value of TTF-1 for EGFR mutations.
Prasad Kapu V Sri Ram,Singh Varsha 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.4
This paper presents the resonance issue of an aged induction motor to restrict the vibrations of the machine to a permissible limit. To mitigate the resonance problem, forced vibration analysis (FVA), natural frequency test (NFT), and experimental modal analysis (EMA) are implemented on an induction motor. FVA and NFT are performed to predict the prime cause of resonance and identify the mechanical fault in the motor casing which is not within the permissible limit. The resonance in the machine leads to an electrical fault. EMA is executed on the stator windings by considering 12 test points that help to determine the looseness of the windings. Using the numerical method and experimental methods, the problem of resonance is identifi ed and resolved. As per ISO standards 10,816, the vibration velocity of the induction motor must be within 5 mm/s. In the induction motor under test, it is observed that the vibration velocity is 15.3 mm/s using numerical analysis which violates the ISO standards. Remodeling and redesign of induction motor are done numerically using ANSYS. These results yield the vibration velocity to be 4.4 mm/s which resolves the resonance.
Bashir Ahmad Dar,Meena Sharma,Baldev Singh,Arup Chakraborty,Parduman R. Sharma,Varsha Shrivastava,Amrita Bhowmik,Dushyant Vyas,Prince Bhatti 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.3
An easy to prepare aluminium pillared interlayered clay (PILC) has been developed as a stable, recyclable and heterogeneous catalyst to promote the one-pot three component synthesis of a-aminophosphonates under solvent-free conditions using grindstone chemistry. Utilization of mild reaction conditions, clean conversion and greater selectivity under grinding conditions along with effortless separation, and purification of reaction products make this process extra attractive.