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3-ϕ Multi-Pulse Ac To Dc Converter Through Zig Zag Transformer
Amarendra Pandey,Rakesh Narvey,Praveen Bansal 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.7
This paper deals with the reduction of Total Harmonic Distortion (THD) by using Multi-pulse AC to DC Conversion technique. The three-phase multi-pulse AC to DC conversion system have a phase-shifting transformer and a three-phase source. Every such type of converter provides a 6-pulse AC to DC conversion system, that’s why in order to produce more sets of 6-pulse systems, a uniform phase-shift is required and hence with proper phase-shifting angle, 12, 18, 24, 30, 36 and higher pulse systems have been produced. The performance improvement of multi-pulse converter is achieved for total harmonics distortion (THD) in supply current, DC voltage ripples and form factor. This paper presents the discussion of multi-pulse improved power quality ac-dc converter (IPQC) configuration, comparative factors and selection of specific.
The Labor Market Effects of FDI: A Panel Data Evidence from Mexico
Amarendra Sharma,Oscar Cardenas 한국국제경제학회 2018 International Economic Journal Vol.32 No.4
This paper explores the effects of Foreign Direct Investment (FDI) inflows on six labor market outcomes by using a panel data of the Mexican states from 2005 to 2015. By relying on the system Generalized Method of Moments estimator to address potential endogeneity of FDI in the labor market outcomes regressions, this study finds that the FDI inflows result in a reduction in the overall unemployment rate. Moreover, the FDI is associated with a decrease in the percentage of employed people with the need and availability to offer more working hours and an increase in the median hourly wage rate. The FDI is not likely to influence the critical employment, informal sector employment, and unemployment duration.
Optimized Space Vector Pulse-width Modulation Technique for a Five-level Cascaded H-Bridge Inverter
Amarendra Matsa,Irfan Ahmed,Madhuri A. Chaudhari 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.5
This paper presents an optimized space vector pulse-width modulation (OSVPWM) technique for a five-level cascaded H-bridge (CHB) inverter. The space vector diagram of the five-level CHB inverter is optimized by resolving it into inner and outer two-level space vector hexagons. Unlike conventional space vector topology, the proposed technique significantly reduces the involved computational time and efforts without compromising the performance of the five-level CHB inverter. A further optimized (FOSVPWM) technique is also presented in this paper, which significantly reduces the complexity and computational efforts. The developed techniques are verified through MATLAB/SIMULINK. Results are compared with sinusoidal pulse-width modulation (SPWM) to prove the validity of the proposed technique. The proposed simulation system is realized by using an XC3S400 field-programmable gate array from Xilinx, Inc. The experiment results are then presented for verification.
Optimized Space Vector Pulse-width Modulation Technique for a Five-level Cascaded H-Bridge Inverter
Matsa, Amarendra,Ahmed, Irfan,Chaudhari, Madhuri A. The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.5
This paper presents an optimized space vector pulse-width modulation (OSVPWM) technique for a five-level cascaded H-bridge (CHB) inverter. The space vector diagram of the five-level CHB inverter is optimized by resolving it into inner and outer two-level space vector hexagons. Unlike conventional space vector topology, the proposed technique significantly reduces the involved computational time and efforts without compromising the performance of the five-level CHB inverter. A further optimized (FOSVPWM) technique is also presented in this paper, which significantly reduces the complexity and computational efforts. The developed techniques are verified through MATLAB/SIMULINK. Results are compared with sinusoidal pulse-width modulation (SPWM) to prove the validity of the proposed technique. The proposed simulation system is realized by using an XC3S400 field-programmable gate array from Xilinx, Inc. The experiment results are then presented for verification.
Dwivedi, Amarendra Dhar,Permana, Rega,Singh, Jitendra Pal,Yoon, Hakwon,Chae, Keun Hwa,Chang, Yoon-Seok,Hwang, Dong Soo Elsevier 2017 Chemical engineering journal Vol.328 No.-
<P><B>Abstract</B></P> <P>Inspired by naturally occurring metal chelation strategy by pyrogallol moiety of tunichromes of marine tunicates, a strong retention of carcinogenic chromium (Cr<SUP>VI</SUP>) is described by mimicking tunichrome matrix as a proof-of-concept investigation in water treatment applications. Harvesting tunichromes tailored with the pyrogallol moiety are extremely difficult owing to aerial sensitivity and purification difficulties, thus proving a challenging synthesis problem. Despite significant interest, knowledge of specific metal coordination in tunicate’s matrix is still ambiguous, hindering study scope. We planned to fabricate a promising tunichrome matrix (TM) tailored with pyrogallol moieties from the Earth-abundant raw materials (gallic acid and chitin nanofiber) at mass scale without artificial aid. Specifically, we aimed at atomistic understanding of contaminant and pyrogallol moiety of TM by examining the structural parameters (redox change, geometrical distortion, coordination bond). Cr <I>K</I>-edge extended X-ray absorption fine structure (EXAFS) corresponds well to nontoxic Cr<SUP>III</SUP> (average four CrO bond lengths of 1.91Å) and a small fraction of Cr<SUP>VI</SUP> (average two CrO bond lengths of 1.62Å). A coupled reductive complexation mechanism was identified by combining near edge X-ray absorption fine structure (NEXAFS) and linear combination fits. From the viewpoint of practical utility and effective performance (nearly 119mg chromium per g weight of TM), the impacts of water chemistry conditions were investigated from a variety of contaminated waters, showing a distinct improvement compared to conventional popular materials. The gained knowledge would be beneficial for utilizing a pyrogallol moiety as an alternative greener and sustainable scavenger, specifically for toxic chromium.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A newly designed nano-bio tool inspired by marine tunicate, a filter feeder. </LI> <LI> Superior retention of Cr<SUP>VI</SUP> by mimicking tunichrome matrix in remediation treatment. </LI> <LI> Pyrogallol – a primary factor in increased efficiency as a proof-of-concept study. </LI> <LI> First comprehensive report on tunichrome’s chromium metal coordination chemistry. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Dwivedi, Amarendra Dhar,Permana, Rega,Singh, Jitendra Pal,Yoon, Hakwon,Chae, Keun Hwa,Chang, Yoon-Seok,Hwang, Dong Soo American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.23
<P>Tunicate, a filter-feeder in seawater, is able to accumulate high amount of metals using intracellular polymer matrices. The woven pyrogallol structures of tunichrome, a small peptide contained in tunicate's blood;Cells, is believed to, be responsible for selective. metal sequestration in tunicates from seawater. However, the intriguing tunichrome matrix is difficult both to harvest from the tunicate and to synthesize massively due to the-extreme oxidation sensitivity of the pyrogallol, moiety which limits the study scope. Here, we succeeded to mimic tunichrome by conjugating two cheap and naturally occurring components: pyrogallol-5-carboxylic acid (gallic acid) and chitin. nanofiber A tunicate-mimetic infiltration matrix of surface-tailored chitin nanofibers with pyrogallol moieties (CGa) demonstrated the versatility of this strategy in generation of ingenious filtration material, especially for unprecedented fine and-Clean gold recovery inside of the tunicate-mimetic infiltration matrix (>99%, 533 mg gold per gram weight), which exceeds that of the,presently most popular materials. Complexation between pyrogallol on the nanofiber and gold-was similar to that of a tunichrome's metal sequestration. Extended X-ray absorption fine Structure, (EXAFS); spectroscopy and data-fitting, elucidated the decreased coordination numbers for Au-Au nearest neighbors, demonstrating that gold coordinated to pyrogallol units, followed by an intramolecular association of Au-0. A catalytic reduction of 4-nitrophenol mediated by the-tunicate-mimetic matrix with harvested gold revealed excellent recyclability up to 30 cycles (similar to 95% reduction), which together with methylene-blue reduction and antimicrobial performances indicates the versatile characteristics,of sustainable processes by the tunichrome mimetics. This strategy opens the door for fast-developing new biomimetic alternatives for precious metal recovery, which is not restricted to gold and can offer a tool for multifaceted soft/hard nanomaterials..</P>
Dwivedi, Amarendra Dhar,Yoon, Hakwon,Singh, Jitendra Pal,Chae, Keun Hwa,Rho, Sang-chul,Hwang, Dong Soo,Chang, Yoon-Seok American Chemical Society 2018 Environmental science & technology Vol.52 No.17
<P>Here, we investigated the fate of nanoscale zerovalent iron (nZVI) on the <I>Cucumis sativus</I> under both hydroponic and soil conditions. Seedlings were exposed to 0, 250, and 1000 mg/L (or mg/kg soil) nZVI during 6-9 weeks of a growth period. Ionic controls were prepared using Fe-EDTA. None of the nZVI treatments affected the plant biomass. On the basis of the total iron contents and the superparamagnetic property of nZVI-exposed roots, there was no evidence of pristine nZVI translocation from the roots to shoots. Electron microscopy revealed that the transformed iron nanoparticles are stored in the root cell membrane and the vacuoles of the leaf parenchymal cells. X-ray absorption spectroscopy identified ferric citrate (41%) and iron (oxyhydr)oxides (59%) as the main transformed products in the roots. The shoot samples indicated a larger proportion of ferric citrate (60%) compared to iron (oxyhydr)oxides (40%). The 1.8-fold higher expression of the <I>CsHA1</I> gene indicated that the plant-promoted transformation of nZVI was driven by protons released from the root layers. The current data provide a basis for two potential nZVI transformation pathways in <I>Cucumis sativus</I>: (1) interaction with low molecular weight organic acid ligands and (2) dissolution-precipitation of the mineral products.</P> [FIG OMISSION]</BR>
Tiliacosine and Tiliasine , two New Bisbenzylisoquinoline Alkaloids from Tiliacora racemosa
Tapan Seal,Amarendra Patra,Gobinda Mukhopadhayay,Biswapati Mukherjee 한국생약학회 2001 Natural Product Sciences Vol.7 No.3
Two new bisbenzylisoquinoline alkaloids tiliacosine (1) and tiliasine (2) were isolated from the leaves of Tiliacora racemosa Colebr.. The structures of these alkaloids were established on the basis of spectral evidence and by the correlation of their ¹H-NMR spectral data with those of the congeners N-methyltiliamosine (3), tiliamosine (4) and tiliacorine (5).