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S. Hata,Y. Miura,T. Ise 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
In this paper, a new family of zero-current-transition (ZCT) power factor correction (PFC) converters is introduced. The proposed converter operates in discrete conduction mode (DCM) and provides soft switching for the main switch and the auxiliary switch with a small inductor and capacitor even in high power / high voltage application. The auxiliary circuit of proposed converter operates for an enough short time compared with the switching period. Furthermore, the auxiliary circuit maintains an almost constant operation time during a power line cycle. As a result, the proposed converter can reduce the losses of the auxiliary circuit. In this study, a steady-state analysis of the proposed converter is described, and features of this converter are compared to ones of zero-voltage-transition (ZVT) converter in theory. These theoretical analyses are verified by a prototype converter.
A Series-elastic Robot for Back-pain Rehabilitation
ElHussein Shata,Kim-Doang Nguyen,Praneel Acharya,Jeffrey Doom 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.2
This paper addresses the robot-assisted rehabilitation of back pain, an epidemic health problem affecting a large portion of the population. The design is composed of two springs in series connected to an end-effector via a pair of antagonistic cables. The spring and cable arrangement forms an elastic coupling from the actuator to the output shaft. An input-output torque model of the series-elastic mechanism is established and studied numerically. The study also illustrates the variation of the mechanism’s effective stiffness by changing the springs’ position. In addition, we built a prototype of the robotic mechanism and design experiments with a robotic manipulator to experimentally investigate its dynamic characteristics. The experimental results confirm the predicted elasticity between the input motion and the output torque at the end-effector. We also observe an agreement between the data generated by the torque model and data collected from the experiments. An experiment with a full-scale robot and a human subject is carried out to investigate the human-robot interaction and the mechanism behavior.
( Hoda Mohamed Abdel Halim Shata ),( Azza Mohmed Noor El-deen ),( Galal Abdel Moen Nawwar ),( Mohmed Abdel Fattah Farid ) 한국응용생명화학회(구 한국농화학회) 2014 Journal of Applied Biological Chemistry (J. Appl. Vol.57 No.4
Black liquor (BL) is a by-product of rice straw pulping process. It is a low costs raw material for production value-adding proteins and enzymes, which has been paid more and more attention to reduce its environmental pollution. Mixed cultures of micelial fungi, Trichoderma reesei Northern Regional Research Laboratory (NRRL)11236, Trichoderma reesei NRRL 6165 and Aspergillus niger strains NRC 5A, NRC 7A, and NRC 9A were evaluated for their ability to produce xylanase using crude hemicellulose (CHC) prepared from BL and peat moss as an inert support under solid state fermentation (SSF). The most potent strains, A. niger NRC 9A (818.26 U/g CHC) and T. reesei NRRL 6165 (100.9±57.14 U/g CHC), were used in a mixed culture to enhance xylanase production by co-culturing under SSF. In the mixed culture, xylanase production (1070.52±12.57 U/g CHC) was nearly1.3 and 10.6-fold increases over the activities attained in their monocultures, A. niger NRC 9A and T. reesei NRRL 6165, respectively. Optimization of the culture parameters of the mixed culture SSF process, concentration of ammonium sulfateand corn steep liquor, CHC/peat moss ratio, inoculum size and ratios of the two strains, initial pH value, initial moisture content and incubation time, exhibited a significant increase (2414.98± 84.02 U/g CHC) in xylanase production than before optimization.
( Hoda Mohamed Abdel Halim Shata ),( Mohamed Abdel Fattah Farid ) 한국응용생명화학회(구 한국농화학회) 2014 Journal of Applied Biological Chemistry (J. Appl. Vol.57 No.3
Various parameters such as solvent selection, concentration, solid/liquid ratio, soaking time, temperature, stationary, shaking conditions, and repeated extractions were investigated in order to determine the optimum extraction conditions of β-glucosidase from bagasse fermented by mixed culture of Aspergillus niger NRC 7A and Aspergillus oryzae NRRL 447. Among various solvents tested, non ionic detergents gave the best results than the inorganic or organic salt solutions and distilled water. The optimum conditions for extraction of β-glucosidase were 30 min soaking time at 40oC under shaking condition at 150 rpm, with solid/liquid ratio 1:15 (w/v), which yielded 2882.74±95.52 U/g fermented culture (g fc) of enzyme activity. With repeated washes under the above optimum conditions, the results showed that enzyme extracted in the 1st and 2nd washes represents about 90% of the total activity.
( Hoda Mohamed Abdel Halim Shata ),( Mohamed Abdel Fattah Farid ) 한국응용생명화학회(구 한국농화학회) 2013 Journal of Applied Biological Chemistry (J. Appl. Vol.56 No.2
Thirteen different Streptomyces isolates were evaluated for their ability to produce keratinase using chicken feather as a sole carbon and nitrogen sources under solid state fermentation (SSF). Streptomyces sp. NRC 13S produced the highest keratinase activity [1,792 U/g fermented substrate (fs)]. The phenotypic characterization and analysis of 16S rDNA sequencing of the isolate were studied. Optimization of SSF medium for keratinase production by the local isolate, Streptomyces sp. NRC13S, was carried out using the one-variable-at-a-time and the statistical approaches. In the first optimization step, the effect of incubation period, initial moisture content, initial pH value of the fermentation medium, and supplementation of some agro-industrial by-products on keratinase production were evaluated. The strain produced about 2,310 U/gfs when it grew on chicken feather with moisture content of 75% (w/w), feather: fodder yeast ratio of 70:30 (w/w), and initial pH 7 using phosphate buffer after 8 days. Based on the results, the Box-Behnken design and response surface methodology were applied to find out the optimal conditions for the enzyme production. The corresponding maximal production of keratinase was about 2,569.38 U/gfs.
( Hoda Mohamed ),( Abdel Halim Shata ),( Mohamed Abdel ),( Fattah Farid ) 한국응용생명화학회(구 한국농화학회) 2012 Journal of Applied Biological Chemistry (J. Appl. Vol.55 No.3
The effects of solvent type and concentration, solid/liquid ratio, extraction time and repeated extraction on recovery ofkeratinase from solid-state fermentation (SSF) of chicken featherby a local Streptomyces sp. NRC 13S were investigated in orderto establish the experimental conditions for keratinase yield.Among solvents tested, 0.5% (v/v) glycerol was the best. Box-Behnken design was used to investigate the effect of relevantvariables on keratinase recovery. The factors investigated weresolid/liquid ratio (1:1.66-1:6.66g/mL), glycerol concentration (0.5-5% v/v) and repeated extraction (1-5 cycle). The resultsshowed that the maximum recovery of keratinase (6933.3 U/gfs)was obtained using 0.5 (v/v) glycerol as extracting solvent, in asolid /liquid ratio of 1:5 and three extraction cycles.
Youn, Jin-Won,Park, Su-Hyung,Lavillette, Dimitri,Cosset, Francois-Loic,Yang, Se-Hwan,Lee, Chang Geun,Jin, Hyun-Tak,Kim, Chang-Min,Shata, Mohamed Tarek M.,Lee, Dong-Hun,Pfahler, Wolfram,Prince, Alfred Wiley Subscription Services, Inc., A Wiley Company 2005 Hepatology Vol.42 No.6
<P>Immune correlates of protection against hepatitis C virus (HCV) infection are not well understood. Here we investigated 2 naive and 6 immunized chimpanzees before and after intravenous challenge, 12 weeks after the last immunization, with 100 50% chimpanzee infectious doses (CID<SUB>50</SUB>) of heterologous genotype 1b HCV. Vaccination with recombinant DNA and adenovirus vaccines expressing HCV core, E1E2, and NS3-5 genes induced long-term HCV-specific antibody and T-cell responses and reduced peak viral load about 100 times compared with controls (5.91 ± 0.38 vs. 3.81 ± 0.71 logs, respectively). There was a statistically significant inverse correlation between peak viral loads and envelope glycoprotein 2 (E2)-specific antibody responses at the time of challenge. Interestingly, one vaccinee that had sterilizing immunity against slightly heterologous virus generated the highest level of E2-specific total and neutralizing antibody responses as well as strong NS3/NS5-specific T-cell proliferative responses. The other four vaccinees with low levels of E2-specific antibody had about 44-fold reduced peak viral loads but eventually developed persistent infections. In conclusion, vaccine-induced E2-specific antibody plays an important role in prevention from nonhomologous virus infection and may provide new insight into the development of an effective HCV vaccine. (HEPATOLOGY 2005;42:1429–1436.)</P>