High Quality DC-DC Boosting Converter Based on Cuk Converter and Advantages of Using It in Multilevel Structures

Rostami, Sajad,Abbasi, Vahid,Kerekes, Tamas The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.4

In this paper, a DC-DC converter is proposed based on the Cuk converter. The proposed converter has high efficiency and it can be used in multilevel DC-DC converters. A reduction of the inductors size in comparison to Cuk converter and a reduction in the inductors resistance negative effects on efficiency are the important points of the proposed converter. Its voltage ripple is reduced when compared to other converters. Its output voltage has a high quality and does not contain spikes. A theoretical analysis demonstrates the positive points of the proposed converter. The design and analysis of the converter are done in continues conduction mode (CCM). Experiments confirm the obtained theoretical equations. The proposed converter voltage gain is similar to that of a conventional Boost converter. As a result, they are compared. The comparison illustrates the advantages of the proposed converter and its higher quality. Furthermore, a prototype of the proposed converter and its combination with a 2x multiplier are built in the lab. Experimental results validate the analysis. In addition, they are in good agreements with each other.

High Quality DC-DC Boosting Converter Based on Cuk Converter and Advantages of Using It in Multilevel Structures

Sajad Rostami,Vahid Abbasi,Tamas Kerekes 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.4

In this paper, a DC-DC converter is proposed based on the Cuk converter. The proposed converter has high efficiency and itcan be used in multilevel DC-DC converters. A reduction of the inductors size in comparison to Cuk converter and a reduction inthe inductors resistance negative effects on efficiency are the important points of the proposed converter. Its voltage ripple isreduced when compared to other converters. Its output voltage has a high quality and does not contain spikes. A theoreticalanalysis demonstrates the positive points of the proposed converter. The design and analysis of the converter are done incontinues conduction mode (CCM). Experiments confirm the obtained theoretical equations. The proposed converter voltagegain is similar to that of a conventional Boost converter. As a result, they are compared. The comparison illustrates theadvantages of the proposed converter and its higher quality. Furthermore, a prototype of the proposed converter and itscombination with a 2x multiplier are built in the lab. Experimental results validate the analysis. In addition, they are in goodagreements with each other.

Thermal buckling analysis of annular FGM plate having variable thickness under thermal load of arbitrary distribution by finite element method

Mansour Mohieddin Ghomshei,Vahid Abbasi 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.4

In this paper, a finite element formulation is developed for analyzing the axisymmetric thermal buckling of FGM annular plates of variable thickness subjected to thermal loads generally distributed nonuniformly along the plate radial coordinate. The FGM assumed to be isotropic with material properties graded in the thickness direction according to a simple power-law in terms of the plate thickness coordinate, and has symmetry with respect to the plate midplane. At first, the pre-buckling plane elasticity problem is developed and solved using the finite element method, to determine the distribution of the pre-buckling in-plane forces in terms of the temperature rise distribution. Subsequently, based on Kierchhoff plate theory and using the principle of minimum total potential energy, the weak form of the differential equation governing the plate thermal stability is derived, then by employing the finite element method, the stability equations are solved numerically to evaluate the thermal buckling load factor. Convergence and validation of the presented finite element model are investigated by comparing the numerical results with those available in the literature. Parametric studies are carried out to cover the effects of parameters including thickness-to-radius ratio, taper parameter and boundary conditions on the thermal buckling load factor of the plates.

Expression Levels of Vascular Endothelial Growth Factors A and C in Patients with Peptic Ulcers and Gastric Cancer

Shirin Taghizadeh,Mojtaba Sankian,Abolghasem Ajami,Mohsen Tehrani,Nasim Hafezi,Rajeeh Mohammadian,Touraj Farazmandfar,Vahid Hosseini,Ali Abbasi,Maryam Ajami 대한위암학회 2014 Journal of gastric cancer Vol.14 No.3

Purpose: Vascular endothelial growth factor (VEGF) is one of the most important growth factors for metastatic tumors. To clarify the roleof VEGF-A and C in patients with peptic ulcer disease (PUD) or gastric cancer (GC), we evaluated the expression levels of these two molecules. We also analyzed the effect of Helicobacter pylori infection on VEGF-A and C expression levels. Materials and Methods: Patients with dyspepsia who needed diagnostic endoscopy were selected and divided into three groups: nonulcerdyspepsia (NUD), PUD, and GC, according to their endoscopic and histopathological results. Fifty-two patients with NUD, 50 withPUD, and 38 with GC were enrolled in this study. H. pylori infection was diagnosed by the rapid urease test. After RNA extraction andsynthesis of cDNA, the expression levels of VEGF-A and C were determined by quantitative reverse transcriptase polymerase chain reaction. Results: The VEGF-C expression level in the PUD and GC groups was significantly higher than that in the NUD group. Moreover, theVEGF-A expression level in the PUD and GC groups was higher than in the NUD group, although the differences were not statisticallysignificant. Significant positive correlations were also observed between the expression levels of these two molecules in the PUD and GCgroups. In addition, the expression levels of these two molecules were higher in H. pylori positive patients with PUD or GC than in H. pylori negative patients of the same groups; however, these differences did not reach statistical significance. Conclusions: Up-regulation of VEGF-C expression during gastric mucosal inflammation may play a role in the development of peptic ulcersor GC.

Expression Levels of Vascular Endothelial Growth Factors A and C in Patients with Peptic Ulcers and Gastric Cancer

Taghizadeh, Shirin,Sankian, Mojtaba,Ajami, Abolghasem,Tehrani, Mohsen,Hafezi, Nasim,Mohammadian, Rajeeh,Farazmandfar, Touraj,Hosseini, Vahid,Abbasi, Ali,Ajami, Maryam The Korean Gastric Cancer Association 2014 Journal of gastric cancer Vol.14 No.3

Purpose: Vascular endothelial growth factor (VEGF) is one of the most important growth factors for metastatic tumors. To clarify the role of VEGF-A and C in patients with peptic ulcer disease (PUD) or gastric cancer (GC), we evaluated the expression levels of these two molecules. We also analyzed the effect of Helicobacter pylori infection on VEGF-A and C expression levels. Materials and Methods: Patients with dyspepsia who needed diagnostic endoscopy were selected and divided into three groups: nonulcer dyspepsia (NUD), PUD, and GC, according to their endoscopic and histopathological results. Fifty-two patients with NUD, 50 with PUD, and 38 with GC were enrolled in this study. H. pylori infection was diagnosed by the rapid urease test. After RNA extraction and synthesis of cDNA, the expression levels of VEGF-A and C were determined by quantitative reverse transcriptase polymerase chain reaction. Results: The VEGF-C expression level in the PUD and GC groups was significantly higher than that in the NUD group. Moreover, the VEGF-A expression level in the PUD and GC groups was higher than in the NUD group, although the differences were not statistically significant. Significant positive correlations were also observed between the expression levels of these two molecules in the PUD and GC groups. In addition, the expression levels of these two molecules were higher in H. pylori positive patients with PUD or GC than in H. pylori negative patients of the same groups; however, these differences did not reach statistical significance. Conclusions: Up-regulation of VEGF-C expression during gastric mucosal inflammation may play a role in the development of peptic ulcers or GC.