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M. G. HOSSEINI AGHDAM,S. H. FATHI,G. B. GHAREHPETIAN 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-
One of the major problems in electric power quality is the harmonic contents. There are several methods of indicating the quantity of harmonic contents. The most widely used measure is the total harmonic distortion (THD). This paper compares the two harmonic optimization techniques, optimal minimization of the total harmonic distortion (OMTHD) technique and optimized harmonic stepped-waveform (OHSW) technique used in multi-level voltage-source inverters. Both techniques are very effective and efficient for improving the quality of the inverter output voltage. First, we describe briefly the cascaded H-bridge multi-level inverter structure. Then, we present the switching algorithm for the inverter based on OHSW and OMTHD techniques. Finally, the results obtained by simulation for the two techniques are analyzed and compared. Simulation results verify the effectiveness of the both techniques in multi-level voltage-source inverter with non-equal DC sources, clarifying the advantages of each technique.
H. M. Daniali,S. M. Varedi,M. Dardel,A. Fathi 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.5
In practice, clearances in the joints are inevitable due to tolerances and defects arising from design and manufacturing. Moreover, thejoints undergo wear and backlash, resulting in poor accuracy and repeatability. This paper presents a novel optimization method forsimultaneously kinematic and dynamic synthesis of a planar four-bar linkage with clearance at the joints. It is well-known that in thepresence of clearance at a joint, the linkage gains an additional, uncontrollable degree of freedom which is the source of error. Here, wesynthesis the path generation problem while controlling the unwanted degrees of freedom by revising the mass distributions of the movinglinks. An algorithm based on particle swarm optimization method solves this highly nonlinear optimization problem with some constraints. Finally, an example is included to demonstrate the efficiency of the algorithm. The results clearly show that the linear and angularaccelerations of the links for the optimal design are very smooth and bounded.
Hamid Radmanesh,S.H.Fathi,G.B. Gharehpetian 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.5
Recently, various types of Solid State Fault Current Limiters (SSFCLs) have been proposed. These SSFCLs can improve the voltage quality, decrease the transmission losses, and also can enhance the distribution network stability but there are some practical problems with these FCLs. This paper proposes a modified FCL with focusing on the components optimization, efficiency improvement and reducing the cost. The suggested FCL uses a series AC reactor with controllable power electronic switches named Thyristor-Controlled AC Reactor (TCAR) which is connected in series with the feeder to limit the fault current and avoid fault current problems, which impairs overall distribution network reliability. The influence of TCAR on the fault current is analyzed using analytical, simulation and laboratory tests. The performance of the proposed TCAR in the simple distribution network is examined. The simulation and experimental results are in a good agreement with together and show the proper operation of the proposed TCAR during the normal and fault operation modes.
Osama Eldamshety,Sherif Kotb,Ashraf Khater,Waleed Elnahas,Sameh Roshdy,Mohamed S. Zahi,Hend M.H. Rashed Elkalla,Omar Farouk,Ahmed Senbel,Adel Fathi,Emad-Eldeen Hamed,Khaled Abdelwahab,Islam A. Elzahby 대한대장항문학회 2020 Annals of Coloproctolgy Vol.36 No.3
Purpose: The study aims to assess the functional outcome of anal sphincter-sparing procedures (SSP) with total mesorectal excision (TME) for anorectal adenocarcinoma. Methods: In a multicentric, prospective, single-group study in the period between December 2012 and November 2017, 93 patients presented with anorectal adenocarcinoma were included in the study. Sixty-nine patients underwent SSP with TME. SSP included the combined approach of transabdominal TME with intersphincteric resection (ISR) or transanal transabdominal TME. Using the per anal examination scoring system (PASS), postoperative anal function was assessed after 1 year. Results: Bowel motility time was 50±19 hours. The time needed for narcotic analgesia was 54±18.8 hours. Mean hospital stay was 15.4±10.25 days. Incidence of evident fecal incontinence after ISR is 10.6% (7 of 67 cases). The PASS findings of 69 cases are as follows: extremely hypotonic 8.6% (6 cases), slightly hypotonic 26.1% (18 cases), normal tone 58% (40 cases), slightly stenotic 3 cases (4.3%), or occluded 2.9% (2 cases). Urinary dysfunction occurred in 1 case (1.4%). Temporary diversion was performed in 61 patients (87.1%). Conclusion: Sphincter preservation with TME for anorectal adenocarcinoma helps avoid permanent stoma and provides reasonable functional outcomes. PASS is a new application for postoperative assessment of anal function.