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  1. Phytoalexins: Current Progress and Future Prospects

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    Philippe Jeandet

    2015-02-01

    Full Text Available Phytoalexins are low molecular weight antimicrobial compounds that are produced by plants as a response to biotic and abiotic stresses. As such they take part in an intricate defense system which enables plants to control invading microorganisms. In the 1950s, research on phytoalexins started with progress in their biochemistry and bio-organic chemistry, resulting in the determination of their structure, their biological activity, as well as mechanisms of their synthesis and catabolism by microorganisms. Elucidation of the biosynthesis of numerous phytoalexins also permitted the use of molecular biology tools for the exploration of the genes encoding enzymes of their synthesis pathways and their regulators. This has led to potential applications for increasing plant resistance to diseases. Phytoalexins display an enormous diversity belonging to various chemical families such as for instance, phenolics, terpenoids, furanoacetylenes, steroid glycoalkaloids, sulfur-containing compounds and indoles.[...

  2. Modulation of Phytoalexin Biosynthesis in Engineered Plants for Disease Resistance

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    Sylvain Cordelier

    2013-07-01

    Full Text Available Phytoalexins are antimicrobial substances of low molecular weight produced by plants in response to infection or stress, which form part of their active defense mechanisms. Starting in the 1950’s, research on phytoalexins has begun with biochemistry and bio-organic chemistry, resulting in the determination of their structure, their biological activity as well as mechanisms of their synthesis and their catabolism by microorganisms. Elucidation of the biosynthesis of numerous phytoalexins has permitted the use of molecular biology tools for the exploration of the genes encoding enzymes of their synthesis pathways and their regulators. Genetic manipulation of phytoalexins has been investigated to increase the disease resistance of plants. The first example of a disease resistance resulting from foreign phytoalexin expression in a novel plant has concerned a phytoalexin from grapevine which was transferred to tobacco. Transformations were then operated to investigate the potential of other phytoalexin biosynthetic genes to confer resistance to pathogens. Unexpectedly, engineering phytoalexins for disease resistance in plants seem to have been limited to exploiting only a few phytoalexin biosynthetic genes, especially those encoding stilbenes and some isoflavonoids. Research has rather focused on indirect approaches which allow modulation of the accumulation of phytoalexin employing transcriptional regulators or components of upstream regulatory pathways. Genetic approaches using gain- or less-of functions in phytoalexin engineering together with modulation of phytoalexin accumulation through molecular engineering of plant hormones and defense-related marker and elicitor genes have been reviewed.

  3. Genetic analysis of the role of phytoalexin detoxification in virulence of the fungus Nectria haematococca on chickpea (Cicer arietinum)

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    Miao, V.P.W.; Vanetten, H.D. (Cornell Univ., Ithaca, NY (United States))

    1992-03-01

    Chickpea (Cicer arietium L.) produces the antimicrobial compounds (phytoalexins) medicarpin and maackiain in response to infection by microorganisms. Nectria haematococca mating population (MP) VI, a fungus pathogenic on chickpea, can metabolize maackiain and medicarpin to less toxic products. These reactions are thought to be detoxification mechanisms in N. haematococca MP VI and required for pathogenesis by this fungus on chickpea. In the present study, these hypotheses were tested by examining the phenotypes of progeny from crosses of the fungus that segregated for genes (Mak genes) controlling phytoalexin metabolism. Mak1 and Mak2, two genes that individually confer the ability to convert maackiain to its 1a-hydroxydienone derivative, were linked to higher tolerance of the phytoalexins and high virulence on chickpea. These results indicate that this metabolic reaction is a mechanism for increased phytoalexin tolerance in the fungus, which thereby allows a higher virulence on chickpea. Mak3, a gene conferring the ability to convert maackiain to its 6a-hydroxypterocarpan derivative, also increased tolerance to maackiain in strains which carried it; however, the contribution of Mak3 to the overall level of pathogenesis could not be evaluated because most progeny from the cross segregating for this gene were low in virulence. Thus, metabolic detoxification of phytoalexins appeared to be necessary, as demonstrated in the Mak1 and Mak2 crosses, but not sufficient by itself, as in the Mak3 cross, for high virulence of N. haematococca MP VI on chickpea.

  4. Phytoalexins of the Pyrinae: Biphenyls and dibenzofurans

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    Cornelia Chizzali

    2012-04-01

    Full Text Available Biphenyls and dibenzofurans are the phytoalexins of the Pyrinae, a subtribe of the plant family Rosaceae. The Pyrinae correspond to the long-recognized Maloideae. Economically valuable species of the Pyrinae are apples and pears. Biphenyls and dibenzofurans are formed de novo in response to infection by bacterial and fungal pathogens. The inducible defense compounds were also produced in cell suspension cultures after treatment with biotic and abiotic elicitors. The antimicrobial activity of the phytoalexins was demonstrated. To date, 10 biphenyls and 17 dibenzofurans were isolated from 14 of the 30 Pyrinae genera. The most widely distributed compounds are the biphenyl aucuparin and the dibenzofuran γ-cotonefuran. The biosynthesis of the two classes of defense compounds is not well understood, despite the importance of the fruit crops. More recent studies have revealed simultaneous accumulation of biphenyls and dibenzofurans, suggesting sequential, rather than the previously proposed parallel, biosynthetic pathways. Elicitor-treated cell cultures of Sorbus aucuparia served as a model system for studying phytoalexin metabolism. The key enzyme that forms the carbon skeleton is biphenyl synthase. The starter substrate for this type-III polyketide synthase is benzoyl-CoA. In apples, biphenyl synthase is encoded by a gene family, members of which are differentially regulated. Metabolism of the phytoalexins may provide new tools for designing disease control strategies for fruit trees of the Pyrinae subtribe.

  5. Phytoalexins of the Pyrinae: Biphenyls and dibenzofurans.

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    Chizzali, Cornelia; Beerhues, Ludger

    2012-01-01

    Biphenyls and dibenzofurans are the phytoalexins of the Pyrinae, a subtribe of the plant family Rosaceae. The Pyrinae correspond to the long-recognized Maloideae. Economically valuable species of the Pyrinae are apples and pears. Biphenyls and dibenzofurans are formed de novo in response to infection by bacterial and fungal pathogens. The inducible defense compounds were also produced in cell suspension cultures after treatment with biotic and abiotic elicitors. The antimicrobial activity of the phytoalexins was demonstrated. To date, 10 biphenyls and 17 dibenzofurans were isolated from 14 of the 30 Pyrinae genera. The most widely distributed compounds are the biphenyl aucuparin and the dibenzofuran γ-cotonefuran. The biosynthesis of the two classes of defense compounds is not well understood, despite the importance of the fruit crops. More recent studies have revealed simultaneous accumulation of biphenyls and dibenzofurans, suggesting sequential, rather than the previously proposed parallel, biosynthetic pathways. Elicitor-treated cell cultures of Sorbus aucuparia served as a model system for studying phytoalexin metabolism. The key enzyme that forms the carbon skeleton is biphenyl synthase. The starter substrate for this type-III polyketide synthase is benzoyl-CoA. In apples, biphenyl synthase is encoded by a gene family, members of which are differentially regulated. Metabolism of the phytoalexins may provide new tools for designing disease control strategies for fruit trees of the Pyrinae subtribe.

  6. Phytoalexins of the Pyrinae: Biphenyls and dibenzofurans

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    Cornelia Chizzali; Ludger Beerhues

    2012-01-01

    Biphenyls and dibenzofurans are the phytoalexins of the Pyrinae, a subtribe of the plant family Rosaceae. The Pyrinae correspond to the long-recognized Maloideae. Economically valuable species of the Pyrinae are apples and pears. Biphenyls and dibenzofurans are formed de novo in response to infection by bacterial and fungal pathogens. The inducible defense compounds were also produced in cell suspension cultures after treatment with biotic and abiotic elicitors. The antimicrobial activity of ...

  7. Three genes for metabolism of the phytoalexin maackiain in the plant pathogen Nectria haematococca: Meiotic instability and relationship to a new gene for pisatin demethylase

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    Miao, V.P.W.; Vanetten, H.D. (Cornell Univ., Ithaca, NY (United States))

    1992-03-01

    Some isolates of the plant-pathogenic fungus Nectria haematococca mating population (MP) VI metabolize maackiain and medicarpin, two antimicrobial compounds (phytoalexins) synthesized by chickpea (Cicer arietinum L.). The enzymatic modifications by the fungus convert the phytoalexins to less toxic derivatives, and this detoxification has been proposed to be important for pathogenesis on chickpea. In the present study, loci controlling maackiain metabolism (Mak genes) were identified by crosses among isolates of N. haematococca MP VI that differed in their ability to metabolize the phytoalexin. Strains carrying Mak1 or Mak2 converted maackiain to 1a-hydroxymaackiain, while those with Mak3 converted it to 6a-hydroxymaackiain. Mak1 and Mak2 were unusual in that they often failed to be inherited by progeny. Mak1 was closely linked to Pda6, a new member in a family of genes in N. haematococca MP VI that encode enzymes for detoxification of pisatin, the phytoalexin synthesized by garden pea. Like Mak1, Pda6 was also transmitted irregularly to progeny. Although the unusual meiotic behaviors of some Mak genes complicate genetic analysis, identification of these genes should afford a more thorough evaluation of the role of phytoalexin detoxification in the pathogenesis of N. haematococca MP VI on chickpea.

  8. Phenolic Phytoalexins in Rice: Biological Functions and Biosynthesis

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    Man-Ho Cho

    2015-12-01

    Full Text Available Phytoalexins are inducible secondary metabolites possessing antimicrobial activity against phytopathogens. Rice produces a wide array of phytoalexins in response to pathogen attacks and environmental stresses. With few exceptions, most phytoalexins identified in rice are diterpenoid compounds. Until very recently, flavonoid sakuranetin was the only known phenolic phytoalexin in rice. However, recent studies have shown that phenylamides are involved in defense against pathogen attacks in rice. Phenylamides are amine-conjugated phenolic acids that are induced by pathogen infections and abiotic stresses including ultra violet (UV radiation in rice. Stress-induced phenylamides, such as N-trans-cinnamoyltryptamine, N-p-coumaroylserotonin and N-cinnamoyltyramine, have been reported to possess antimicrobial activities against rice bacterial and fungal pathogens, an indication of their direct inhibitory roles against invading pathogens. This finding suggests that phenylamides act as phytoalexins in rice and belong to phenolic phytoalexins along with sakuranetin. Phenylamides also have been implicated in cell wall reinforcement for disease resistance and allelopathy of rice. Synthesis of phenolic phytoalexins is stimulated by phytopathogen attacks and abiotic challenges including UV radiation. Accumulating evidence has demonstrated that biosynthetic pathways including the shikimate, phenylpropanoid and arylmonoamine pathways are coordinately activated for phenolic phytoalexin synthesis, and related genes are induced by biotic and abiotic stresses in rice.

  9. Silicon-mediated accumulation of flavonoid phytoalexins in cucumber.

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    Fawe, A; Abou-Zaid, M; Menzies, J G; Bélanger, R R

    1998-05-01

    ABSTRACT The controversial role of silicon in plant disease resistance, described mostly as a passive mechanical protection, has been addressed. Conclusive evidence is presented that silicon is involved in the increased resistance of cucumber to powdery mildew by enhancing the antifungal activity of infected leaves. This antifungal activity was attributable to the presence of low-molecular-weight metabolites. One of these metabolites, described here as a phytoalexin, was identified as a flavonol aglycone rhamnetin (3,5,3',4'-tetrahydroxy-7-O-methoxyflavone). This is the first report of a phytoalexin for this chemical group in the plant kingdom and of a flavonol phytoalexin in cucumber, a chemical defense long believed to be nonexistent in the family Cucurbitaceae. The antifungal activity of leaf extracts was better expressed after acid hydrolysis, extending to another plant species the concept that some phytoalexins are synthesized as glycosylated phytoalexins or their precursors.

  10. Phytoalexin Induction in French Bean 1

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    Dixon, Richard A.; Dey, Prakash M.; Lawton, Michael A.; Lamb, Christopher J.

    1983-01-01

    Treatment of hypocotyl sections or cell suspension cultures of dwarf French bean (Phaseolus vulgaris L.) with an abiotic elicitor (denatured ribonuclease A) resulted in increased extractable activity of the enzyme l-phenylalanine ammonia-lyase. This induction could be transmitted from treated cells through a dialysis membrane to cells which were not in direct contact with the elicitor. In hypocotyl sections, induction of isoflavonoid phytoalexin accumulation was also transmitted across a dialysis membrane, although levels of insoluble, lignin-like phenolic material remained unchanged in elicitor-treated and control sections. In bean cell suspension cultures, the induction of phenylalanine ammonia-lyase in cells separated from ribonuclease-treated cells by a dialysis membrane was also accompanied by increases in the activities of chalcone synthase and chalcone isomerase, two enzymes previously implicated in the phytoalexin defense response. Such intercellular transmission of elicitation did not occur in experiments with cells treated with a biotic elicitor preparation heat-released from the cell walls of the bean pathogen Colletotrichum lindemuthianum. The results confirm and extend previous suggestions that a low molecular weight, diffusible factor of host plant origin is involved (in French bean) in the intercellular transmission of the elicitation response to abiotic elicitors. PMID:16662813

  11. Red Card for Pathogens: Phytoalexins in Sorghum and Maize

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    Alana Poloni

    2014-06-01

    Full Text Available Cereal crop plants such as maize and sorghum are constantly being attacked by a great variety of pathogens that cause large economic losses. Plants protect themselves against pathogens by synthesizing antimicrobial compounds, which include phytoalexins. In this review we summarize the current knowledge on phytoalexins produced by sorghum (luteolinidin, apigeninidin and maize (zealexin, kauralexin, DIMBOA and HDMBOA. For these molecules, we highlight biosynthetic pathways, known intermediates, proposed enzymes, and mechanisms of elicitation. Finally, we discuss the involvement of phytoalexins in plant resistance and their possible application in technology, medicine and agriculture. For those whose world is round we tried to set the scene in the context of a hypothetical football game in which pathogens fight with phytoalexins on the different playing fields provided by maize and sorghum.

  12. Red card for pathogens: phytoalexins in sorghum and maize.

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    Poloni, Alana; Schirawski, Jan

    2014-06-30

    Cereal crop plants such as maize and sorghum are constantly being attacked by a great variety of pathogens that cause large economic losses. Plants protect themselves against pathogens by synthesizing antimicrobial compounds, which include phytoalexins. In this review we summarize the current knowledge on phytoalexins produced by sorghum (luteolinidin, apigeninidin) and maize (zealexin, kauralexin, DIMBOA and HDMBOA). For these molecules, we highlight biosynthetic pathways, known intermediates, proposed enzymes, and mechanisms of elicitation. Finally, we discuss the involvement of phytoalexins in plant resistance and their possible application in technology, medicine and agriculture. For those whose world is round we tried to set the scene in the context of a hypothetical football game in which pathogens fight with phytoalexins on the different playing fields provided by maize and sorghum.

  13. Red Card for Pathogens : Phytoalexins in Sorghum and Maize

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    Alana Poloni; Jan Schirawski

    2014-01-01

    Cereal crop plants such as maize and sorghum are constantly being attacked by a great variety of pathogens that cause large economic losses. Plants protect themselves against pathogens by synthesizing antimicrobial compounds, which include phytoalexins. In this review we summarize the current knowledge on phytoalexins produced by sorghum (luteolinidin, apigeninidin) and maize (zealexin, kauralexin, DIMBOA and HDMBOA). For these molecules, we highlight biosynthetic pathways, known intermediate...

  14. Tenualexin, other phytoalexins and indole glucosinolates from wild cruciferous species.

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    Pedras, M Soledade C; Yaya, Estifanos E

    2014-06-01

    In general, the chemodiversity of phytoalexins, elicited metabolites involved in plant defense mechanisms against microbial pathogens, correlates with the biodiversity of their sources. In this work, the phytoalexins produced by four wild cruciferous species (Brassica tournefortii, Crambe abyssinica (crambe), Diplotaxis tenuifolia (sand rocket), and Diplotaxis tenuisiliqua (wall rocket)) were identified and quantified by HPLC with photodioarray and electrospray mass detectors. In addition, the production of indole glucosinolates, biosynthetic precursors of cruciferous phytoalexins, was evaluated. Tenualexin, (=2-(1,4-dimethoxy-1H-indol-3-yl)acetonitrile), the first cruciferous phytoalexin containing two MeO substituents in the indole ring, was isolated from D. tenuisiliqua, synthesized, and evaluated for antifungal activity. The phytoalexins cyclobrassinin and spirobrassinin were detected in B. tournefortii and C. abyssinica, whereas rutalexin and 4-methoxybrassinin were only found in B. tournefortii. D. tenuifolia, and D. tenuisiliqua produced 2-(1H-indol-3-yl)acetonitriles as phytoalexins. Because tenualexin appears to be one of the broad-range antifungals occurring in crucifers, it is suggested that D. tenuisiliqua may have disease resistance traits important to be incorporated in commercial breeding programs.

  15. Jasmonoyl-l-isoleucine is required for the production of a flavonoid phytoalexin but not diterpenoid phytoalexins in ultraviolet-irradiated rice leaves.

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    Miyamoto, Koji; Enda, Isami; Okada, Toshiki; Sato, Yumiko; Watanabe, Kohei; Sakazawa, Tomoko; Yumoto, Emi; Shibata, Kyomi; Asahina, Masashi; Iino, Moritoshi; Yokota, Takao; Okada, Kazunori; Yamane, Hisakazu

    2016-10-01

    Rice produces low-molecular-weight antimicrobial compounds known as phytoalexins, in response to not only pathogen attack but also abiotic stresses including ultraviolet (UV) irradiation. Rice phytoalexins are composed of diterpenoids and a flavonoid. Recent studies have indicated that endogenous jasmonyl-l-isoleucine (JA-Ile) is not necessarily required for the production of diterpenoid phytoalexins in blast-infected or CuCl2-treated rice leaves. However, JA-Ile is required for the accumulation of the flavonoid phytoalexin, sakuranetin. Here, we investigated the roles of JA-Ile in UV-induced phytoalexin production. We showed that UV-irradiation induces the biosynthesis of JA-Ile and its precursor jasmonic acid. We also showed that rice jasmonate biosynthesis mutants produced diterpenoid phytoalexins but not sakuranetin in response to UV, indicating that JA-Ile is required for the production of sakuranetin but not diterpenoid phytoalexins in UV-irradiated rice leaves.

  16. Phytoalexin Accumulation in Colombian Bean Varieties and Aminosugars as Elicitors

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    Fernando Echeverri

    2002-11-01

    Full Text Available The accumulation of isoflavonoid phytoalexins was studied in several Colombian bean cultivars resistant and susceptible to Colletotrichum lindemuthianum fungus, the causal agent of anthrachnose disease. A time-course accumulation analysis on seedlings treated with CuCl2 showed that phaseollin production was higher in resistant cultivars than in susceptible ones. Also, a defensive role of phytoalexins was demostrated when extracts containing this pterocarpan exhibited antifungal activity against C. lindemuthianum. In addition, the elicitor activity of some aminosugars was also established.

  17. Biosynthesis, elicitation and roles of monocot terpenoid phytoalexins

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    A long standing goal in plant defense research is to optimize the protective function of biochemicals that impede pathogen and pest attack. Nearly 40 years ago pathogen-inducible non-volatile diterpenoids were described in rice and demonstrated to function as potent antimicrobial phytoalexins. Using...

  18. Identity, regulation, and activity of inducible diterpenoid phytoalexins in maize.

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    Schmelz, Eric A; Kaplan, Fatma; Huffaker, Alisa; Dafoe, Nicole J; Vaughan, Martha M; Ni, Xinzhi; Rocca, James R; Alborn, Hans T; Teal, Peter E

    2011-03-29

    Phytoalexins constitute a broad category of pathogen- and insect-inducible biochemicals that locally protect plant tissues. Because of their agronomic significance, maize and rice have been extensively investigated for their terpenoid-based defenses, which include insect-inducible monoterpene and sesquiterpene volatiles. Rice also produces a complex array of pathogen-inducible diterpenoid phytoalexins. Despite the demonstration of fungal-induced ent-kaur-15-ene production in maize over 30 y ago, the identity of functionally analogous maize diterpenoid phytoalexins has remained elusive. In response to stem attack by the European corn borer (Ostrinia nubilalis) and fungi, we observed the induced accumulation of six ent-kaurane-related diterpenoids, collectively termed kauralexins. Isolation and identification of the predominant Rhizopus microsporus-induced metabolites revealed ent-kaur-19-al-17-oic acid and the unique analog ent-kaur-15-en-19-al-17-oic acid, assigned as kauralexins A3 and B3, respectively. Encoding an ent-copalyl diphosphate synthase, fungal-induced An2 transcript accumulation precedes highly localized kauralexin production, which can eventually exceed 100 μg · g(-1) fresh weight. Pharmacological applications of jasmonic acid and ethylene also synergize the induced accumulation of kauralexins. Occurring at elevated levels in the scutella of all inbred lines examined, kauralexins appear ubiquitous in maize. At concentrations as low as 10 μg · mL(-1), kauralexin B3 significantly inhibited the growth of the opportunistic necrotroph R. microsporus and the causal agent of anthracnose stalk rot, Colletotrichum graminicola. Kauralexins also exhibited significant O. nubilalis antifeedant activity. Our work establishes the presence of diterpenoid defenses in maize and enables a more detailed analysis of their biosynthetic pathways, regulation, and crop defense function.

  19. Fungal elicitors of the phytoalexin response in higher plants

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    West, Charles A.

    1981-09-01

    Several types of fungal molecules including cell wall polysaccharides, polypeptides, glycoproteins and lipid molecules have been found to serve as elicitors of phytoalexins in higher plants. Recent work has shown that an extracellular enzyme, endopolygalacturonase, from culture filtrates of the fungus Rhizopus stolonifer elicits the biosynthesis of an antifungal antibiotic, casbene, in extracts of treated castor bean ( Ricinus communis L.) seedlings. A suggested mode of action of this elicitor in the plant in which fragments of the plant cell wall released through the catalytic action of the enzyme serve as secondary elicitors to trigger the plant response is proposed on the basis of preliminary observations. Possible modes of interaction of other types of fungal elicitors with plants are also discussed.

  20. Elicitor induced activation of the methylerythritol phosphate pathway toward phytoalexins biosynthesis in rice.

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    Okada, Atsushi; Shimizu, Takafumi; Okada, Kazunori; Kuzuyama, Tomohisa; Koga, Jinichiro; Shibuya, Naoto; Nojiri, Hideaki; Yamane, Hisakazu

    2007-09-01

    Diterpenoid phytoalexins such as momilactones and phytocassanes are produced via geranylgeranyl diphosphate in suspension-cultured rice cells after treatment with a chitin elicitor. We have previously shown that the production of diterpene hydrocarbons leading to phytoalexins and the expression of related biosynthetic genes are activated in suspension-cultured rice cells upon elicitor treatment. To better understand the elicitor-induced activation of phytoalexin biosynthesis, we conducted microarray analysis using suspension-cultured rice cells collected at various times after treatment with chitin elicitor. Hierarchical cluster analysis revealed two types of early-induced expression (EIE-1, EIE-2) nodes and a late-induced expression (LIE) node that includes genes involved in phytoalexins biosynthesis. The LIE node contains genes that may be responsible for the methylerythritol phosphate (MEP) pathway, a plastidic biosynthetic pathway for isopentenyl diphosphate, an early precursor of phytoalexins. The elicitor-induced expression of these putative MEP pathway genes was confirmed by quantitative reverse-transcription PCR. 1-Deoxy-D: -xylulose 5-phosphate synthase (DXS), 1-deoxy-D: -xylulose 5-phosphate reductoisomerase (DXR), and 4-(cytidine 5'-diphospho)-2-C-methyl-D: -erythritol synthase (CMS), which catalyze the first three committed steps in the MEP pathway, were further shown to have enzymatic activities that complement the growth of E. coli mutants disrupted in the corresponding genes. Application of ketoclomazone and fosmidomycin, inhibitors of DXS and DXR, respectively, repressed the accumulation of diterpene-type phytoalexins in suspension cells treated with chitin elicitor. These results suggest that activation of the MEP pathway is required to supply sufficient terpenoid precursors for the production of phytoalexins in infected rice plants.

  1. The Metabolism of Sunflower Phytoalexins Ayapin and Scopoletin

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    Tal, Beni; Robeson, David J.

    1986-01-01

    The coumarin phytoalexins ayapin and scopoletin accumulate in longitudinal stem sections of sunflower (Helianthus annuus L., Compositae) following inoculation with fungi both pathogenic (Alternaria helianthi) and nonpathogenic (Helminthosporium carbonum) to this plant. Both compounds were induced more rapidly, and they attained higher levels in tissue inoculated with the heterologous pathogen H. carbonum as compared with the sunflower pathogen A. helianthi. Similarly, scopoletin and ayapin accumulated to comparatively low concentrations following inoculation with a second sunflower pathogen, Phoma macdonaldii. Scopoletin was biosynthesized de novo following inoculation, although levels of its glucoside scopolin exceeded those of the aglucone in both infected and control tissues. Both scopoletin and scopolin were routinely detected in trace amounts in uninoculated tissue. In contrast, ayapin was not detected as a component of uninfected plants. When [14C]scopoletin was supplied to induced sunflower stem sections about 36% of the recovered radioactivity was in the form of ayapin. In vitro studies demonstrated that A. helianthi possessed the ability to rapidly degrade both scopoletin and ayapin, whereas H. carbonum was much less efficient in these traits. The differential degradation of these compounds by phytopathogenic fungi which do not attack sunflower is also discussed. PMID:16664986

  2. Phenylpropanoid defence responses in transgenic Lotus corniculatus 1. Glutathione elicitation of isoflavan phytoalexins in transformed root cultures.

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    Robbins, M P; Hartnoll, J; Morris, P

    1991-06-01

    When Agrobacterium rhizogenes transformed root cultures of Lotus corniculatus were treated with glutathione, isoflavan phytoalexins accumulated in both tissue and culture medium. This accumulation of phytoalexins was preceded by a transient increase in the activity of phenylalanine ammonia lyase (PAL). Elicitation of PAL occurred throughout the growth curve of Lotus 'hairy roots' and in different sectors of transformed root material.

  3. Phenylphenalenone-type Phytoalexins from Unripe Buñgulan Banana Fruit.

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    Kamo, T; Kato, N; Hirai, N; Tsuda, M; Fujioka, D; Ohigashi, H

    1998-01-01

    Fourteen phenylphenalenone-type phytoalexins (1-14), including three new compounds, were isolated from the peel of unripe Musa acuminata [AAA] cv. Buñgulan fruit which had been injured and then inoculated with conidia of Colletotrichum musae. These new phytoalexins were identified as (+)-cis-2,3-dihydro-2,3-dihydroxy-4-(4'-hydroxyphenyl)phenalen-1-one (12), 9-(3',4'-dimethoxyphenyl)-2-methoxyphenalen-1-one (13) and 9-(4'-hydroxyphenyl)-2-methoxyphenalen-1-one (14). The ratios of the relative intensities of the [M](+)/[M-H](+) ions or [M-H2O](+)/[M-H2O-H](+) ions in the EI mass spectra were applied to discriminate between 4- and 9-phenylphenalenones. An antifungal test on the phytoalexins showed that a phenolic hydroxyl group was essential for the activity.

  4. Tryptophan-derived sulfur-containing phytoalexins--a general overview.

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    Ruszkowska, Joanna; Wróbel, Jerzy T

    2003-01-01

    Phytoalexins are low molecular weight antimicrobial compounds that are synthesized and accumulated in plants after their exposure to pathogenic microorganisms (bacteria, fungi, viruses and protozoans). They are extensively studied now as promising antifungal, potentially anticancer and plant diseases controlling agents. The article pertains to a group of indole-derived phytoalexins--brassinins, containing at least one sulfur atom in the side chain or in the ring(s), isolated from the cruciferous plants. Up today more than 20 compounds, closely related biogenetically, but exhibiting diversified biological activity have been identified. The survey summerises most promising recent results pertaining practical application of brassinins and camalexins.

  5. Host-pathogen interactions. XV. Fungal glucans which elicit phytoalexin accumulation in soybean also elicit the accumulation of phytoalexins in other plants

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    Cline, K.; Wade, M.; Albersheim, P.

    1978-01-01

    A ..beta..-glucan isolated from the mycelial walls of Phytophthora megasperma var. sojae and a glucan purified from yeast extract stimulate the accumulation of phytoalexins in red kidney bean, Phaseolus vulgaris, and stimulate the accumulation of the phytoalexin, rishitin, in potato tubers, Solanum tuberosum. Treatment of kidney bean cotyledons with the glucan elicitors resulted in the accumulation of at least five fungistatic compounds. These compounds migrate during thin layer chromatography identically to the fungistatic compounds which accumulate in kidney beans which have been inoculated with Colletotrichum lindemuthianum, a fungal pathogen of kidney beans. Potatoes accumulate as much as 29 micrograms of rishitin per gram fresh weight following exposure to the glucan from Phytophthora megasperma va. sojae and as much as 19.5 micrograms of rishitin per gram fresh weight following exposure to yeast glucan.

  6. Deciphering the Role of Phytoalexins in Plant-Microorganism Interactions and Human Health

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    Philippe Jeandet

    2014-11-01

    Full Text Available Phytoalexins are low molecular weight antimicrobial compounds that are produced by plants as a response to biotic and abiotic stresses. As such they take part in an intricate defense system which enables plants to control invading microorganisms. In this review we present the key features of this diverse group of molecules, namely their chemical structures, biosynthesis, regulatory mechanisms, biological activities, metabolism and molecular engineering.

  7. Biphenyl Phytoalexin in Sorbus pohuashanensis Suspension Cell Induced by Yeast Extract

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    Liangyun Zhou; Jian Yang; Guang Yang; Chuanzhi Kang; Wenjuan Xiao; Chaogeng Lv; Sheng Wang; Jinfu Tang; Lanping Guo

    2016-01-01

    Biphenyls are unique phytoalexins de novo synthesized in plants in response to pathogen attack. These compounds are found in Maloideae, a subfamily of the Rosaceae. The anti-microbial activities of biphenyls have been reported in a number of studies and they appear to represent an important defense strategy against pathogens common in the Maloideae, such as species in Malus, Pyrus, Sorbus, and Chaenomeles. Here, cell suspension cultures of Sorbus pohuashanensis were established to study biphe...

  8. Cloning, expression, and characterization of (+)-delta-cadinene synthase: a catalyst for cotton phytoalexin biosynthesis.

    Science.gov (United States)

    Chen, X Y; Chen, Y; Heinstein, P; Davisson, V J

    1995-12-20

    In cotton, sesquiterpene phytoalexins are elicited in response to bacterial or fungal infection. A Gossypium arboreum cell suspension culture which produces the sesquiterpene phytoalexin gossypol showed a time-dependent 10-fold increase in a 1.9-kb mRNA in response to a challenge by a preparation from Verticillium dahliae. The mRNA prepared from these elicited cultures was used to isolated two cDNA clones that contain open frames coding for proteins of 554 amino acids with M(r) 64,096 and 64,118. The encoded protein shows a significant degree of sequence identity with the other known plant terpene cyclases. Western blot analyses with a cross-reactive monoclonal antibody from a related sesquiterpene synthase in Nicotiana tabacum showed a time-dependent increase of a 65-kDa protein which reached a maximal level 24 h post elicitor treatment. The encoded protein from the pXC1 cDNA was produced in Escherichia coli and purified by affinity column chromatography. The enzymatic properties of this protein were identified by a radiochemical assay for cyclization of farnesyldiphosphate and a product structure was assigned by GC-MS, chiral phase GC, and NMR analyses as (+)-delta-cadinene. The fungal-elicited production of a (+)-delta-cadinene synthase is consistent with a role for this enzyme as the first committed step in the pathways leading to the related phytoalexins gossypol and lacinilene C in cotton.

  9. Biphenyl Phytoalexin in Sorbus pohuashanensis Suspension Cell Induced by Yeast Extract.

    Science.gov (United States)

    Zhou, Liangyun; Yang, Jian; Yang, Guang; Kang, Chuanzhi; Xiao, Wenjuan; Lv, Chaogeng; Wang, Sheng; Tang, Jinfu; Guo, Lanping

    2016-09-14

    Biphenyls are unique phytoalexins de novo synthesized in plants in response to pathogen attack. These compounds are found in Maloideae, a subfamily of the Rosaceae. The anti-microbial activities of biphenyls have been reported in a number of studies and they appear to represent an important defense strategy against pathogens common in the Maloideae, such as species in Malus, Pyrus, Sorbus, and Chaenomeles. Here, cell suspension cultures of Sorbus pohuashanensis were established to study biphenyl phytoalexins formation after yeast extract (YE) treatment. An ultra-performance liquid chromatography (UPLC) method coupled with quadrupole time of flight mass spectrometry (Q-TOF-MS) LC-MS/MS was applied to determine the time course of these biphenyl biomarkers accumulation in YE-treated S. pohuashanensis suspension cells. The results of quantitative analyses show the content of Noraucuparin, 2'-Hydroxyaucuparin, and their glycosides initially increased, then decreased over time. The Noraucuparin content reached its highest (225.76 μg·g(-1)) at 18 h after treatment, 6 hours earlier than that of Noraucuparin 5-O-β-d-glucopyranoside. The content of 2'-Hydroxyaucuparin reached its highest (422.75 μg·g(-1)) at 30 h after treatment, also earlier than that of its glycoside. The understanding of phytoalexin metabolism in this study may provide a basis for improving Maloideae resistance to pathogens.

  10. Biphenyl Phytoalexin in Sorbus pohuashanensis Suspension Cell Induced by Yeast Extract

    Directory of Open Access Journals (Sweden)

    Liangyun Zhou

    2016-09-01

    Full Text Available Biphenyls are unique phytoalexins de novo synthesized in plants in response to pathogen attack. These compounds are found in Maloideae, a subfamily of the Rosaceae. The anti-microbial activities of biphenyls have been reported in a number of studies and they appear to represent an important defense strategy against pathogens common in the Maloideae, such as species in Malus, Pyrus, Sorbus, and Chaenomeles. Here, cell suspension cultures of Sorbus pohuashanensis were established to study biphenyl phytoalexins formation after yeast extract (YE treatment. An ultra-performance liquid chromatography (UPLC method coupled with quadrupole time of flight mass spectrometry (Q-TOF-MS LC−MS/MS was applied to determine the time course of these biphenyl biomarkers accumulation in YE-treated S. pohuashanensis suspension cells. The results of quantitative analyses show the content of Noraucuparin, 2′-Hydroxyaucuparin, and their glycosides initially increased, then decreased over time. The Noraucuparin content reached its highest (225.76 μg·g−1 at 18 h after treatment, 6 hours earlier than that of Noraucuparin 5-O-β-d-glucopyranoside. The content of 2′-Hydroxyaucuparin reached its highest (422.75 μg·g−1 at 30 h after treatment, also earlier than that of its glycoside. The understanding of phytoalexin metabolism in this study may provide a basis for improving Maloideae resistance to pathogens.

  11. The phytoalexin resveratrol regulates the initiation of hypersensitive cell death in Vitis cell.

    Directory of Open Access Journals (Sweden)

    Xiaoli Chang

    Full Text Available Resveratrol is a major phytoalexin produced by plants in response to various stresses and promotes disease resistance. The resistance of North American grapevine Vitis rupestris is correlated with a hypersensitive reaction (HR, while susceptible European Vitis vinifera cv. 'Pinot Noir' does not exhibit HR, but expresses basal defence. We have shown previously that in cell lines derived from the two Vitis species, the bacterial effector Harpin induced a rapid and sensitive accumulation of stilbene synthase (StSy transcripts, followed by massive cell death in V. rupestris. In the present work, we analysed the function of the phytoalexin resveratrol, the product of StSy. We found that cv. 'Pinot Noir' accumulated low resveratrol and its glycoside trans-piceid, whereas V. rupestris produced massive trans-resveratrol and the toxic oxidative δ-viniferin, indicating that the preferred metabolitism of resveratrol plays role in Vitis resistance. Cellular responses to resveratrol included rapid alkalinisation, accumulation of pathogenesis-related protein 5 (PR5 transcripts, oxidative burst, actin bundling, and cell death. Microtubule disruption and induction of StSy were triggered by Harpin, but not by resveratrol. Whereas most responses proceeded with different amplitude for the two cell lines, the accumulation of resveratrol, and the competence for resveratrol-induced oxidative burst differed in quality. The data lead to a model, where resveratrol, in addition to its classical role as antimicrobial phytoalexin, represents an important regulator for initiation of HR-related cell death.

  12. Host-Pathogen Interactions: XV. Fungal Glucans Which Elicit Phytoalexin Accumulation in Soybean Also Elicit the Accumulation of Phytoalexins in Other Plants.

    Science.gov (United States)

    Cline, K; Wade, M; Albersheim, P

    1978-12-01

    A beta-glucan isolated from the mycelial walls of Phytophthora megasperma var. sojae and a glucan purified from yeast extract stimulate the accumulation of phytoalexins in red kidney bean, Phaseolus vulgaris, and stimulate the accumulation of the phytoalexin, rishitin, in potato tubers, Solanum tuberosum. These glucans have previously been shown to be potent elicitors of glyceollin accumulation in soybean, Glycine max.Treatment of kidney bean cotyledons with the glucan elicitors resulted in the accumulation of at least five fungistatic compounds. These compounds migrate during thin layer chromatography identically to the fungistatic compounds which accumulate in kidney beans which have been inoculated with Colletotrichum lindemuthianum, a fungal pathogen of kidney beans.Potatoes accumulate as much as 29 micrograms of rishitin per gram fresh weight following exposure to the glucan from Phytophthora megasperma var. sojae and as much as 19.5 micrograms of rishitin per gram fresh weight following exposure to yeast glucan. Potatoes accumulated 28 micrograms of rishitin per gram fresh weight following inoculation with live Phytophthora megasperma var. sojae.

  13. Metabolic changes in elicitor-treated bean cells. Selectivity of enzyme induction in relation to phytoalexin accumulation.

    Science.gov (United States)

    Robbins, M P; Bolwell, G P; Dixon, R A

    1985-05-02

    Treatment of cell suspension cultures of Phaseolus vulgaris c.v. Immuna with an elicitor preparation heat-released from the cell walls of the phytopathogenic fungus Colletotrichum lindemuthianum resulted in rapid accumulation of the prenylated 5-hydroxyisoflavanone phytoalexin kievitone followed by later accumulation of the pterocarpan-derived phytoalexin phaseollin. Kievitone formation was preceded by rapid transient increases in the extractable activities of the enzymes L-phenylalanine ammonia-lyase and chalcone synthase. The extractable activities of 15 enzymes were measured in the cell cultures during the period of kievitone accumulation. The results suggest a highly selective induction of enzymes associated directly with the phytoalexin pathway. No induction of enzymes of pathways diverging from or providing substrates for the phenylpropanoid----isoflavonoid pathway was observed. The increase in glutamate dehydrogenase activity in control cultures was prevented by elicitor application. A comparison of enzyme activities in control and Colletotrichum-infected bean hypocotyls provided further evidence of the selective induction of enzymes of phytoalexin synthesis, although peroxidase, glutamate dehydrogenase and glutamate synthase activities were higher in infected than in healthy hypocotyls. It is concluded that the major enzymic changes occurring in elicitor-treated bean cells are probably those directly associated with defence mechanisms such as the formation of isoflavonoid phytoalexins (this paper) or accumulation of phenolic compounds and hydroxyproline-protein in the cell walls [Bolwell, G. P. et al. (1985) Eur. J. Biochem. 148, 571-578].

  14. Jasmonic Acid, Abscisic Acid, and Salicylic Acid Are Involved in the Phytoalexin Responses of Rice to Fusarium fujikuroi, a High Gibberellin Producer Pathogen.

    Science.gov (United States)

    Siciliano, Ilenia; Amaral Carneiro, Greice; Spadaro, Davide; Garibaldi, Angelo; Gullino, Maria Lodovica

    2015-09-23

    Fusarium fujikuroi, the causal agent of bakanae disease, is the main seedborne pathogen on rice. To understand the basis of rice resistance, a quantitative method to simultaneously detect phytohormones and phytoalexins was developed by using HPLC-MS/MS. With this method dynamic profiles and possible interactions of defense-related phytohormones and phytoalexins were investigated on two rice cultivars, inoculated or not with F. fujikuroi. In the resistant cultivar Selenio, the presence of pathogen induced high production of phytoalexins, mainly sakuranetin, and symptoms of bakanae were not observed. On the contrary, in the susceptible genotype Dorella, the pathogen induced the production of gibberellin and abscisic acid and inhibited jasmonic acid production, phytoalexins were very low, and bakanae symptoms were observed. The results suggested that a wide range of secondary metabolites are involved in plant defense against pathogens and phytoalexin synthesis could be an important factor for rice resistance against bakanae disease.

  15. Wavelength Converters

    DEFF Research Database (Denmark)

    Kloch, Allan; Hansen, Peter Bukhave; Wolfson, David;

    1999-01-01

    at 2.5 Gbit/s, the regeneration causes a reduction of the required input power to an in-line EDFA of ~6 dB for a power penalty of 1 dB at a bit error rate of 10-9. If two converters are concatenated the power requirement is reduced ~8 dB. Obviously, the power reduction allows for longer spans between....... It is predicted that jitter accumulation can be minimised by using a 9-10 dB ratio between the signal and CW power also assuring a high extinction ratio. Using this guideline simulations show that 20 cross-gain modulation converters can be cascaded at 10 Gbit/s with only ~20 ps of accumulated jitter...... and an extinction ratio of ~10 dB.The regenerative capabilities of the cross-phase converters are described and verified experimentally at 20 Gbit/s, where the noise redistribution and improvement of the signal-to-noise ratio clearly is demonstrated by controlling the input power to an EDFA. In a similar experiment...

  16. Defesas químicas de plantas: fitoalexinas Chemical defense of plants: phytoalexins

    Directory of Open Access Journals (Sweden)

    Márcia Regina Braga

    1987-01-01

    Full Text Available A resistência de plantas ao ataque de microorganismos causadores de doenças relaciona-se à presença de barreiras físicas e (juímicas de defesa. Dentre as barreiras químicas destacam-se as fitoalexinas, substâncias fungitoxicas sintetizadas de novo pelas plantas principalmente após a invasão ou o contato de seus tecidos com microorganismos, Essas substâncias englobam vários grupos compostos naturais tais como terpenos, isoflavonóides e poliacetilenos e seu acúmulo pode ser induzido por organismos vivos, seus produtos (elíciadores ou ainda agentes químicos, como sais de metais pesados, ou físicos (congelamento, luz U.U.. Alguns aspectos abordados nesta revisão são: a ocorrência de fitoalexinas em angiospermas, a relação entre sua natureza química e o grupo taxonômico das plantas que as produzem, a sua ação sobre organismos pró e eucarióticos. São descritas também os fatores que interferem nas respostas das plantas aos agentes indutores e as técnicas usuais para a indução e detecção de fitoalexinas. O papel dos eliciadores na indução da sâitese de fitoalexinas e o mecanismo pelo qual exercem sua função indutora são discutidos. Nesse contexto está incluída a teoria das oligossacarinas, fragmentos de parede celular que parecem controlar não só a resposta de defesa em plantas mas também outros fenômenos fisiológicos em plantas.Chemical defense of plants: phytoalexins - This review describes the concept of phytoalexins as a chemical defense of plants against microorganisms as well as a response of plants to chemical or physical agents. The current information on phytoalexins is presented, regarding the following aspects: occurrence in angiosperms; relation-snips between chemical composition and taxonomy; toxicity; factors affecting plant response; techniques for induction and detection of phytoalexins; role of elicitors and mechanisms of action. The latter includes the oligosaccharins-fragments of cell

  17. Concise syntheses of the cruciferous phytoalexins brassilexin, sinalexin, wasalexins, and analogues: expanding the scope of the vilsmeier formylation.

    Science.gov (United States)

    Pedras, M Soledade C; Jha, Mukund

    2005-03-04

    Efficient syntheses of the phytoalexins brassilexin, sinalexin, and analogues are demonstrated through the application of the Vilsmeier formylation to indoline-2-thiones followed by a new aqueous ammonia workup procedure. Similarly, a very concise two-pot synthesis of the phytoalexins wasalexins using sequential formylation-amination of indolin-2-ones is described. Remarkably, this novel aqueous ammonia workup allows the sequential one-pot formylation-amination, expanding substantially the scope of the Vilsmeier formylation of both indoline-2-thiones and indolin-2-ones. The examination of the formylation-amination reaction and optimization of conditions, as well as the syntheses and antifungal activities of several brassilexin analogues, are reported.

  18. Co-ordinated synthesis of phytoalexin biosynthetic enzymes in biologically-stressed cells of bean (Phaseolus vulgaris L.).

    Science.gov (United States)

    Cramer, C L; Bell, J N; Ryder, T B; Bailey, J A; Schuch, W; Bolwell, G P; Robbins, M P; Dixon, R A; Lamb, C J

    1985-02-01

    Changes in the rates of synthesis of three enzymes of phenyl-propanoid biosynthesis in Phaseolus vulgaris L. (dwarf French bean) have been investigated by immunoprecipitation of [S]methionine-labeled enzyme subunits with mono-specific antisera. Elicitor causes marked, rapid but transient co-ordinated increases in the rate of synthesis of phenyl-alanine ammonia-lyase, chalcone synthase and chalcone isomerase concomitant with the phase of rapid increase in enzyme activity at the onset of accumulation of phenyl-propanoid-derived phytoalexin antibiotics in suspension cultures of P. vulgaris. Co-ordinate induction of enzyme synthesis is also observed in hypocotyl tissue during race:cultivar-specific interactions with Colletotrichum lindemuthianum, causal agent of anthracnose. In an incompatible interaction (host resistant) there are early increases apparently localized to the initial site of infection prior to the onset of phytoalexin accumulation and expression of hypersensitive resistance. In contrast, in a compatible interaction (host susceptible) there is no induction of synthesis in the early stages of infection, but a delayed widespread response at the onset of lesion formation associated with attempted lesion limitation. It is concluded that expression of the phytoalexin defense response in biologically stressed cells of P. vulgaris characteristically involves co-ordinate induction of synthesis of phytoalexin biosynthetic enzymes.

  19. Hormesis of Glyceollin I, an Induced Phytoalexin from Soybean, on Budding Yeast Chronological Lifespan Extension

    Directory of Open Access Journals (Sweden)

    Yuancai Liu

    2014-01-01

    Full Text Available Glyceollin I, an induced phytoalexin isolated from soybean, has been reported to have various bioactivities, including anti-bacterial, anti-nematode, anti-fungal, anti-estrogenic and anti-cancer, anti-oxidant, anti-inflammatory, insulin sensitivity enhancing, and attenuation of vascular contractions. Here we show that glyceollin I has hormesis and extends yeast life span at low (nM doses in a calorie restriction (CR-dependent manner, while it reduces life span and inhibits yeast cell proliferation at higher (μM doses. In contrast, the other two isomers (glyceollin II and III cannot extend yeast life span and only show life span reduction and antiproliferation at higher doses. Our results in anti-aging activity indicate that glyceollin I might be a promising calorie restriction mimetic candidate, and the high content of glyceollins could improve the bioactivity of soybean as functional food ingredients.

  20. The jasmonate precursor, 12-oxo-phytodienoic acid, induces phytoalexin synthesis in Petroselinum crispum cell cultures.

    Science.gov (United States)

    Dittrich, H; Kutchan, T M; Zenk, M H

    1992-08-31

    The pentacyclic biosynthetic precursor of jasmonic acid, 12-oxo-phytodienoic acid, was found to induce synthesis of the major flavonoid, apiin, in cell suspension cultures of Petroselinum crispum. The accumulation of apiin was preceded by an increase in the relative levels of poly (A)+ RNAs that code for the flavonoid biosynthetic enzymes phenylalanine ammonia lyase, 4-coumarate:CoA ligase and chalcone synthase, Poly (A)+ RNAs reached maximal levels at approximately 4-6 h after the addition of elicitor while flavonoids continued to accumulate in the cultures for at least 6 days. 12-Oxo-phytodienoic acid is the first pentacyclic precursor in the jasmonic acid biosynthetic chain which functions as a signal transducer for phytoalexin induction.

  1. Phytoalexin Phenalenone Derivatives Inactivate Mosquito Larvae and Root-knot Nematode as Type-II Photosensitizer

    Science.gov (United States)

    Song, Runjiang; Feng, Yian; Wang, Donghui; Xu, Zhiping; Li, Zhong; Shao, Xusheng

    2017-02-01

    Phytoalexins phenalenones (PNs) are phytochemicals biosynthesized inside the plant in responsive to exterior threat. PNs are excellent type-II photosensitizers, which efficiently produce singlet oxygen upon light irradiation. Based on the core functional structure of PNs, novel PN derivatives were synthesized here and their singlet oxygen generating abilities and their phototoxicity were evaluated. At the presence of light, these PNs have photoinduced toxicity towards Aedes albopictus larvae and nematode Meloidogyne incognita, while the activity lost in the dark. The obvious tissue damage was observed on the treated mosquito larvae and nematode due to the generation of singlet oxygen. Our results revealed the potential of phenalenones as photoactivated agents for mosquito and root-knot nematode management together with light.

  2. The outer membrane protein TolC is required for phytoalexin resistance and virulence of the fire blight pathogen Erwinia amylovora

    OpenAIRE

    2009-01-01

    Summary Erwinia amylovora causes fire blight on several plant species such as apple and pear, which produce diverse phytoalexins as defence mechanisms. An evolutionary successful pathogen thus must develop resistance mechanisms towards these toxic compounds. The E. amylovora outer membrane protein, TolC, might mediate phytoalexin resistance through its interaction with the multidrug efflux pump, AcrAB. To prove this, a tolC mutant and an acrB/tolC double mutant were constructed. The minimal i...

  3. Formation of biphenyl and dibenzofuran phytoalexins in the transition zones of fire blight-infected stems of Malus domestica cv. 'Holsteiner Cox' and Pyrus communis cv. 'Conference'.

    Science.gov (United States)

    Chizzali, Cornelia; Khalil, Mohammed N A; Beuerle, Till; Schuehly, Wolfgang; Richter, Klaus; Flachowsky, Henryk; Peil, Andreas; Hanke, Magda-Viola; Liu, Benye; Beerhues, Ludger

    2012-05-01

    In the rosaceous subtribe Pyrinae (formerly subfamily Maloideae), pathogen attack leads to formation of biphenyls and dibenzofurans. Accumulation of these phytoalexins was studied in greenhouse-grown grafted shoots of Malus domestica cv. 'Holsteiner Cox' and Pyrus communis cv. 'Conference' after inoculation with the fire blight bacterium, Erwinia amylovora. No phytoalexins were found in leaves. However, both classes of defence compounds were detected in the transition zone of stems. The flanking stem segments above and below this zone, which were necrotic and healthy, respectively, were devoid of detectable phytoalexins. The transition zone of apple stems contained the biphenyls 3-hydroxy-5-methoxyaucuparin, aucuparin, noraucuparin and 2'-hydroxyaucuparin and the dibenzofurans eriobofuran and noreriobofuran. In pear, aucuparin, 2'-hydroxyaucuparin, noreriobofuran and in addition 3,4,5-trimethoxybiphenyl were detected. The total phytoalexin content in the transition zone of pear was 25 times lower than that in apple. Leaves and stems of mock-inoculated apple and pear shoots lacked phytoalexins. A number of biphenyls and dibenzofurans were tested for their in vitro antibacterial activity against some Erwinia amylovora strains. The most efficient compound was 3,5-dihydroxybiphenyl (MIC=115 μg/ml), the immediate product of biphenyl synthase which initiates phytoalexin biosynthesis.

  4. Expression of Biphenyl Synthase Genes and Formation of Phytoalexin Compounds in Three Fire Blight-Infected Pyrus communis Cultivars

    OpenAIRE

    Cornelia Chizzali; Swiddan, Asya K.; Sahar Abdelaziz; Mariam Gaid; Klaus Richter; Fischer, Thilo C.; Benye Liu; Ludger Beerhues

    2016-01-01

    Pear (Pyrus communis) is an economically important fruit crop. Drops in yield and even losses of whole plantations are caused by diseases, most importantly fire blight which is triggered by the bacterial pathogen Erwinia amylovora. In response to the infection, biphenyls and dibenzofurans are formed as phytoalexins, biosynthesis of which is initiated by biphenyl synthase (BIS). Two PcBIS transcripts were cloned from fire blight-infected leaves and the encoded enzymes were characterized regard...

  5. Expression of Biphenyl Synthase Genes and Formation of Phytoalexin Compounds in Three Fire Blight-Infected Pyrus communis Cultivars.

    Directory of Open Access Journals (Sweden)

    Cornelia Chizzali

    Full Text Available Pear (Pyrus communis is an economically important fruit crop. Drops in yield and even losses of whole plantations are caused by diseases, most importantly fire blight which is triggered by the bacterial pathogen Erwinia amylovora. In response to the infection, biphenyls and dibenzofurans are formed as phytoalexins, biosynthesis of which is initiated by biphenyl synthase (BIS. Two PcBIS transcripts were cloned from fire blight-infected leaves and the encoded enzymes were characterized regarding substrate specificities and kinetic parameters. Expression of PcBIS1 and PcBIS2 was studied in three pear cultivars after inoculation with E. amylovora. Both PcBIS1 and PcBIS2 were expressed in 'Harrow Sweet', while only PcBIS2 transcripts were detected in 'Alexander Lucas' and 'Conference'. Expression of the PcBIS genes was observed in both leaves and the transition zone of the stem; however, biphenyls and dibenzofurans were only detected in stems. The maximum phytoalexin level (~110 μg/g dry weight was observed in the transition zone of 'Harrow Sweet', whereas the concentrations were ten times lower in 'Conference' and not even detectable in 'Alexander Lucas'. In 'Harrow Sweet', the accumulation of the maximum phytoalexin level correlated with the halt of migration of the transition zone, whereby the residual part of the shoot survived. In contrast, the transition zones of 'Alexander Lucas' and 'Conference' advanced down to the rootstock, resulting in necrosis of the entire shoots.

  6. Development and Validation of a New HPLC Method for the Determination of Biphenyl and Dibenzofuran Phytoalexins in Rosaceae.

    Science.gov (United States)

    Teotia, Deepa; Saini, Shashank Sagar; Gaid, Mariam; Beuerle, Till; Beerhues, Ludger; Sircar, Debabrata

    2016-07-01

    A simple, precise, rapid and accurate isocratic reversed-phase high-performance liquid chromatographic method was developed and validated for the simultaneous determination of biphenyl (aucuparin and noraucuparin) and dibenzofuran (eriobofuran) phytoalexin from elicitor treated cell culture of Sorbus aucuparia (mountain ash). These phytoalexins play crucial role in combating scab disease in many commercially important rosaceous plants, such as apple, pear and mountain ash. The isocratic separation was performed in a Luna C18 reversed-phase column (250 × 4.6 mm, 5 μm particle size) using a mobile phase of 1 mM trifluoroacetic acid (TFA) in water with methanol [40:60 (v/v)]. Quantization of phytoalexin was carried out on Shimadzu-HPLC system using a Photo Diode Array (PDA) detector at 254 nm by comparing the peak area. Peak purity and identity were confirmed by UV spectroscopy and ESI-MS-MS in the negative ion mode. The different analytical performance parameters such as linearity, accuracy, precision, limit of detection and limit of quantification were determined according to the International Conference on Harmonization guidelines. Linearity was observed in the concentration range of 3-400 µg/mL with excellent correlation coefficient (R(2) ≥ 0.995). This newly developed method is rapid, easy, cost-effective and can be used for monitoring scab-resistance potential of rosaceous plants.

  7. Expression of Biphenyl Synthase Genes and Formation of Phytoalexin Compounds in Three Fire Blight-Infected Pyrus communis Cultivars.

    Science.gov (United States)

    Chizzali, Cornelia; Swiddan, Asya K; Abdelaziz, Sahar; Gaid, Mariam; Richter, Klaus; Fischer, Thilo C; Liu, Benye; Beerhues, Ludger

    2016-01-01

    Pear (Pyrus communis) is an economically important fruit crop. Drops in yield and even losses of whole plantations are caused by diseases, most importantly fire blight which is triggered by the bacterial pathogen Erwinia amylovora. In response to the infection, biphenyls and dibenzofurans are formed as phytoalexins, biosynthesis of which is initiated by biphenyl synthase (BIS). Two PcBIS transcripts were cloned from fire blight-infected leaves and the encoded enzymes were characterized regarding substrate specificities and kinetic parameters. Expression of PcBIS1 and PcBIS2 was studied in three pear cultivars after inoculation with E. amylovora. Both PcBIS1 and PcBIS2 were expressed in 'Harrow Sweet', while only PcBIS2 transcripts were detected in 'Alexander Lucas' and 'Conference'. Expression of the PcBIS genes was observed in both leaves and the transition zone of the stem; however, biphenyls and dibenzofurans were only detected in stems. The maximum phytoalexin level (~110 μg/g dry weight) was observed in the transition zone of 'Harrow Sweet', whereas the concentrations were ten times lower in 'Conference' and not even detectable in 'Alexander Lucas'. In 'Harrow Sweet', the accumulation of the maximum phytoalexin level correlated with the halt of migration of the transition zone, whereby the residual part of the shoot survived. In contrast, the transition zones of 'Alexander Lucas' and 'Conference' advanced down to the rootstock, resulting in necrosis of the entire shoots.

  8. The phytoalexin-inducible multidrug efflux pump AcrAB contributes to virulence in the fire blight pathogen, Erwinia amylovora.

    Science.gov (United States)

    Burse, Antje; Weingart, Helge; Ullrich, Matthias S

    2004-01-01

    The enterobacterium Erwinia amylovora causes fire blight on members of the family Rosaceae, with economic importance on apple and pear. During pathogenesis, the bacterium is exposed to a variety of plant-borne antimicrobial compounds. In plants of Rosaceae, many constitutively synthesized isoflavonoids affecting microorganisms were identified. Bacterial multidrug efflux transporters which mediate resistance toward structurally unrelated compounds might confer tolerance to these phytoalexins. To prove this hypothesis, we cloned the acrAB locus from E. amylovora encoding a resistance nodulation division-type transport system. In Escherichia coli, AcrAB of E. amylovora conferred resistance to hydrophobic and amphiphilic toxins. An acrB-deficient E. amylovora mutant was impaired in virulence on apple rootstock MM 106. Furthermore, it was susceptible toward extracts of leaves of MM 106 as well as to the apple phytoalexins phloretin, naringenin, quercetin, and (+)-catechin. The expression of acrAB was determined using the promoterless reporter gene egfp. The acrAB operon was up-regulated in vitro by the addition of phloretin and naringenin. The promoter activity of acrR, encoding a regulatory protein involved in acrAB expression, was increased by naringenin. In planta, an induction of acrAB was proved by confocal laser scanning microscopy. Our results strongly suggest that the AcrAB transport system plays an important role as a protein complex required for virulence of E. amylovora in resistance toward apple phytoalexins and that it is required for successful colonization of a host plant.

  9. Biosynthesis of the biphenyl phytoalexin aucuparin in Sorbus aucuparia cell cultures treated with Venturia inaequalis.

    Science.gov (United States)

    Khalil, Mohammed N A; Beuerle, Till; Müller, Andreas; Ernst, Ludger; Bhavanam, Vijaya B R; Liu, Benye; Beerhues, Ludger

    2013-12-01

    Aucuparin is the most widely distributed biphenyl phytoalexin in the rosaceous subtribe Pyrinae, which includes the economically important fruit trees apple and pear. The biphenyl scaffold is formed by biphenyl synthase, which catalyzes biosynthesis of 3,5-dihydroxybiphenyl. Conversion of this precursor to aucuparin (3,5-dimethoxy-4-hydroxybiphenyl) was studied in cell cultures of Sorbus aucuparia after treatment with an elicitor preparation from the scab-causing fungus Venturia inaequalis. The sequence of the biosynthetic steps detected was O-methylation - 4-hydroxylation - O-methylation. The two alkylation reactions were catalyzed by distinct methyltransferases, which differed in pH and temperature optima as well as stability. Biphenyl 4-hydroxylase was a microsomal cytochrome P450 monooxygenase, whose activity was appreciably decreased by the addition of established P450 inhibitors. When fed to V. inaequalis-treated S. aucuparia cell cultures, radioactively labeled 3,5-dihydroxybiphenyl was not only incorporated into aucuparin but also into the dibenzofuran eriobofuran, the accumulation of which paralleled that of aucuparin. However, biphenyl 2'-hydroxylase activity proposed to be involved in dibenzofuran formation was detected in neither microsomes nor cell-free extracts in the presence of NADPH and 2-oxoglutarate, respectively. Nevertheless, a basis for studying biphenyl biosynthesis at the gene level is provided.

  10. Quantification of camalexin, a phytoalexin from Arabidopsis thaliana: a comparison of five analytical methods.

    Science.gov (United States)

    Beets, Caryn; Dubery, Ian

    2011-12-15

    Camalexin is a phytoalexin of Arabidopsis thaliana and an important component of inducible defenses. Accurate quantification of low concentrations suffers from interference by structurally related metabolites. A. thaliana plants were induced with silver nitrate and camalexin was extracted using methanol and identified and quantified by (i) TLC as a blue fluorescent band, (ii) microtiter plate-based fluorescence spectroscopy, (iii) GC on a midpolar column coupled to flame ionization detection, (iv) C(18) HPLC coupled to a photodiode detector, and (v) UPLC coupled to a mass spectrometer detector. Standard curves over the range of 0.1-15 μg ml(-1) gave R(2) values from 0.996 to 0.999. The different methods were compared and evaluated for their ability to detect and quantify increasing concentrations (qualitative technique for the identification of camalexin and fluorescence spectroscopy is subject to quenching when performed on crude extracts. Comparable results were obtained with GC-FID, HPLC-PDA, and UPLC-MS, with UPLC-MS having the added advantage of short analysis times and detection based on accurate mass.

  11. Green peach aphid infestation induces Arabidopsis PHYTOALEXIN-DEFICIENT4 expression at site of insect feeding.

    Science.gov (United States)

    Louis, Joe; Mondal, Hossain A; Shah, Jyoti

    2012-11-01

    The Arabidopsis thaliana PHYTOALEXIN-DEFICIENT4 (PAD4) protein, which has homology to lipases, is required for phloem-based resistance against the green peach aphid (GPA; Myzus persicae Sülzer). PAD4 modulates antibiotic and antixenotic defenses against GPA. PAD4 in conjunction with its interacting partner ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1) also functions in basal resistance to bacterial and oomycete pathogens by promoting salicylic acid (SA)-dependent and SA-independent defenses. By contrast, neither EDS1 nor SA is required for PAD4-controlled defense against GPA. Distinct molecular activities of PAD4 are involved in different aspects of Arabidopsis defense against GPA and pathogens. Histochemical analysis of plants containing a PAD4p:GUS chimera, which expresses the GUS reporter from the PAD4 promoter, indicated strong PAD4 promoter activity at the site of penetration of the vasculature by the insect stylet. GUS activity was also observed in non-vascular tissues of GPA-infested leaves, thus raising the possibility that a combination of distinct PAD4 activities in vascular and non-vascular tissues contribute to Arabidopsis defense against GPA.

  12. Degradation of the benzoxazolinone class of phytoalexins is important for virulence of Fusarium pseudograminearum towards wheat.

    Science.gov (United States)

    Kettle, Andrew J; Batley, Jacqueline; Benfield, Aurelie H; Manners, John M; Kazan, Kemal; Gardiner, Donald M

    2015-12-01

    Wheat, maize, rye and certain other agriculturally important species in the Poaceae family produce the benzoxazolinone class of phytoalexins on pest and pathogen attack. Benzoxazolinones can inhibit the growth of pathogens. However, certain fungi can actively detoxify these compounds. Despite this, a clear link between the ability to detoxify benzoxazolinones and pathogen virulence has not been shown. Here, through comparative genome analysis of several Fusarium species, we have identified a conserved genomic region around the FDB2 gene encoding an N-malonyltransferase enzyme known to be involved in benzoxazolinone degradation in the maize pathogen Fusarium verticillioides. Expression analyses demonstrated that a cluster of nine genes was responsive to exogenous benzoxazolinone in the important wheat pathogen Fusarium pseudograminearum. The analysis of independent F. pseudograminearum FDB2 knockouts and complementation of the knockout with FDB2 homologues from F. graminearum and F. verticillioides confirmed that the N-malonyltransferase enzyme encoded by this gene is central to the detoxification of benzoxazolinones, and that Fdb2 contributes quantitatively to virulence towards wheat in head blight inoculation assays. This contrasts with previous observations in F. verticillioides, where no effect of FDB2 mutations on pathogen virulence towards maize was observed. Overall, our results demonstrate that the detoxification of benzoxazolinones is a strategy adopted by wheat-infecting F. pseudograminearum to overcome host-derived chemical defences. © 2015 BSPP AND JOHN WILEY & SONS LTD.

  13. Identification of UV-Induced Diterpenes Including a New Diterpene Phytoalexin, Phytocassane F, from Rice Leaves by Complementary GC/MS and LC/MS Approaches.

    Science.gov (United States)

    Horie, Kiyotaka; Inoue, Yasuno; Sakai, Miki; Yao, Qun; Tanimoto, Yosuke; Koga, Jinichiro; Toshima, Hiroaki; Hasegawa, Morifumi

    2015-04-29

    Rice phytoalexins are regarded as one of the most important weapons against pathogenic microorganisms. We attempted to identify novel phytoalexins and their derivatives using GC/MS and LC/MS analyses. Diterpene derivatives, 9β-pimara-7,15-diene-3β,6β,19-triol, 1, stemar-13-en-2α-ol, 2, and 1α,2α-dihydroxy-ent-12,15-cassadiene-3,11-dione, 3, were isolated from UV-irradiated rice leaves by chromatographic methods. These structures were confirmed by 1D- and 2D-NMR and MS analyses. Interestingly, all three compounds were accumulated following an infection by the rice blast pathogen Magnaporthe oryzae. Compounds 1 and 2 exhibited weak antifungal activity and may be the biosynthetic intermediates of rice phytoalexins momilactones and oryzalexin S, respectively. Compound 3 exhibited relatively high inhibitory activity against the fungal mycelial growth of M. oryzae to the same extent as the known phytoalexin phytocassane A. We conclude that 3 is a member of the cassane-type phytoalexin family and propose the name phytocassane F.

  14. Effect of salicylic acid and structurally related compounds in the accumulation of phytoalexins in cotyledons of common bean (Phaseolus vulgaris L.) cultivars.

    Science.gov (United States)

    Durango, Diego; Pulgarin, Natalia; Echeverri, Fernando; Escobar, Gustavo; Quiñones, Winston

    2013-09-02

    In the present work, isoflavonoid phytoalexin production in response to the application of salicylic acid in cotyledons of four common bean (Phaseolus vulgaris) cultivars (SA) was evaluated. The time-course and dose-response profiles of the induction process were established by quantifying the isoflavonoids by HPLC. Cotyledons of anthracnose-resistant cultivars induced by SA produced substantially higher phytoalexin contents as compared to the susceptible ones. In addition, maximum levels of phytoalexins (50-100 fold increases) were reached between 96 and 144 h, and when a concentration of SA from 3.62 to 14.50 mM was used. The observations also indicate that there was a relatively good correlation between the phytoalexin contents and the inhibitory effect against C. lindemuthianum; the higher antifungal activity was observed during the first 48 hours for extracts from cotyledons treated with SA at 1.45 and 3.62 mM, and between 96 and 144 h after induction. Finally, compounds structurally related to SA (dihydro-quinazolinones and some imines) showed a strong elicitor effect. Moreover, induced extracts from cotyledons treated with these potential elicitors, besides the properly elicitors, displayed a weak to moderated antifungal activity. These compounds may be considered good candidates for developing of new phytoprotectants. Furthermore, phytoalexin-eliciting substances may contribute for selecting disease resistant cultivars.

  15. Effect of Salicylic Acid and Structurally Related Compounds in the Accumulation of Phytoalexins in Cotyledons of Common Bean (Phaseolus vulgaris L. Cultivars

    Directory of Open Access Journals (Sweden)

    Winston Quiñones

    2013-09-01

    Full Text Available In the present work, isoflavonoid phytoalexin production in response to the application of salicylic acid in cotyledons of four common bean (Phaseolus vulgaris cultivars (SA was evaluated. The time-course and dose-response profiles of the induction process were established by quantifying the isoflavonoids by HPLC. Cotyledons of anthracnose-resistant cultivars induced by SA produced substantially higher phytoalexin contents as compared to the susceptible ones. In addition, maximum levels of phytoalexins (50–100 fold increases were reached between 96 and 144 h, and when a concentration of SA from 3.62 to 14.50 mM was used. The observations also indicate that there was a relatively good correlation between the phytoalexin contents and the inhibitory effect against C. lindemuthianum; the higher antifungal activity was observed during the first 48 hours for extracts from cotyledons treated with SA at 1.45 and 3.62 mM, and between 96 and 144 h after induction. Finally, compounds structurally related to SA (dihydro-quinazolinones and some imines showed a strong elicitor effect. Moreover, induced extracts from cotyledons treated with these potential elicitors, besides the properly elicitors, displayed a weak to moderated antifungal activity. These compounds may be considered good candidates for developing of new phytoprotectants. Furthermore, phytoalexin-eliciting substances may contribute for selecting disease resistant cultivars.

  16. Expression of Biphenyl Synthase Genes and Formation of Phytoalexin Compounds in Three Fire Blight-Infected Pyrus communis Cultivars

    Science.gov (United States)

    Chizzali, Cornelia; Swiddan, Asya K.; Abdelaziz, Sahar; Gaid, Mariam; Richter, Klaus; Fischer, Thilo C.; Liu, Benye; Beerhues, Ludger

    2016-01-01

    Pear (Pyrus communis) is an economically important fruit crop. Drops in yield and even losses of whole plantations are caused by diseases, most importantly fire blight which is triggered by the bacterial pathogen Erwinia amylovora. In response to the infection, biphenyls and dibenzofurans are formed as phytoalexins, biosynthesis of which is initiated by biphenyl synthase (BIS). Two PcBIS transcripts were cloned from fire blight-infected leaves and the encoded enzymes were characterized regarding substrate specificities and kinetic parameters. Expression of PcBIS1 and PcBIS2 was studied in three pear cultivars after inoculation with E. amylovora. Both PcBIS1 and PcBIS2 were expressed in ‘Harrow Sweet’, while only PcBIS2 transcripts were detected in ‘Alexander Lucas’ and ‘Conference’. Expression of the PcBIS genes was observed in both leaves and the transition zone of the stem; however, biphenyls and dibenzofurans were only detected in stems. The maximum phytoalexin level (~110 μg/g dry weight) was observed in the transition zone of ‘Harrow Sweet’, whereas the concentrations were ten times lower in ‘Conference’ and not even detectable in ‘Alexander Lucas’. In ‘Harrow Sweet’, the accumulation of the maximum phytoalexin level correlated with the halt of migration of the transition zone, whereby the residual part of the shoot survived. In contrast, the transition zones of ‘Alexander Lucas’ and ‘Conference’ advanced down to the rootstock, resulting in necrosis of the entire shoots. PMID:27410389

  17. Wavelength converter technology

    DEFF Research Database (Denmark)

    Kloch, Allan; Hansen, Peter Bukhave; Poulsen, Henrik Nørskov;

    1999-01-01

    Wavelength conversion is important since it ensures full flexibility of the WDM network layer. Progress in optical wavelength converter technology is reviewed with emphasis on all-optical wavelength converter types based on semiconductor optical amplifiers....

  18. Wavelength converter technology

    DEFF Research Database (Denmark)

    Kloch, Allan; Hansen, Peter Bukhave; Poulsen, Henrik Nørskov;

    1999-01-01

    Wavelength conversion is important since it ensures full flexibility of the WDM network layer. Progress in optical wavelength converter technology is reviewed with emphasis on air-optical wavelength converter types based on semiconductor optical amplifiers....

  19. Technologies for converter topologies

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Yan; Zhang, Haiyu

    2017-02-28

    In some embodiments of the disclosed inverter topologies, an inverter may include a full bridge LLC resonant converter, a first boost converter, and a second boost converter. In such embodiments, the first and second boost converters operate in an interleaved manner. In other disclosed embodiments, the inverter may include a half-bridge inverter circuit, a resonant circuit, a capacitor divider circuit, and a transformer.

  20. Power Converters for Accelerators

    CERN Document Server

    Visintini, R

    2015-01-01

    Particle accelerators use a great variety of power converters for energizing their sub-systems; while the total number of power converters usually depends on the size of the accelerator or combination of accelerators (including the experimental setup), the characteristics of power converters depend on their loads and on the particle physics requirements: this paper aims to provide an overview of the magnet power converters in use in several facilities worldwide.

  1. Transcriptomic and metabolomic analyses identify a role for chlorophyll catabolism and phytoalexin during Medicago nonhost resistance against Asian soybean rust.

    Science.gov (United States)

    Ishiga, Yasuhiro; Uppalapati, Srinivasa Rao; Gill, Upinder S; Huhman, David; Tang, Yuhong; Mysore, Kirankumar S

    2015-08-12

    Asian soybean rust (ASR) caused by Phakopsora pachyrhizi is a devastating foliar disease affecting soybean production worldwide. Understanding nonhost resistance against ASR may provide an avenue to engineer soybean to confer durable resistance against ASR. We characterized a Medicago truncatula-ASR pathosystem to study molecular mechanisms of nonhost resistance. Although urediniospores formed appressoria and penetrated into epidermal cells of M. truncatula, P. pachyrhizi failed to sporulate. Transcriptomic analysis revealed the induction of phenylpropanoid, flavonoid and isoflavonoid metabolic pathway genes involved in the production of phytoalexin medicarpin in M. truncatula upon infection with P. pachyrhizi. Furthermore, genes involved in chlorophyll catabolism were induced during nonhost resistance. We further characterized one of the chlorophyll catabolism genes, Stay-green (SGR), and demonstrated that the M. truncatula sgr mutant and alfalfa SGR-RNAi lines showed hypersensitive-response-like enhanced cell death upon inoculation with P. pachyrhizi. Consistent with transcriptomic analysis, metabolomic analysis also revealed the accumulation of medicarpin and its intermediate metabolites. In vitro assay showed that medicarpin inhibited urediniospore germination and differentiation. In addition, several triterpenoid saponin glycosides accumulated in M. truncatula upon inoculation with P. pachyrhizi. In summary, using multi-omic approaches, we identified a correlation between phytoalexin production and M. truncatula defense responses against ASR.

  2. Host specificity of Sporisorium reilianum is tightly linked to generation of the phytoalexin luteolinidin by Sorghum bicolor.

    Science.gov (United States)

    Zuther, Katja; Kahnt, Jörg; Utermark, Jan; Imkampe, Julia; Uhse, Simon; Schirawski, Jan

    2012-09-01

    The smut fungus Sporisorium reilianum occurs in two varieties (S. reilianum f. sp. reilianum and S. reilianum f. sp. zeae) that cause head smut disease on sorghum and maize, respectively. Prior to plant infection, compatible haploid sporidia of S. reilianum fuse to form infectious dikaryotic hyphae that penetrate the leaf surface, spread throughout the plant, and reach the inflorescences, in which spore formation occurs. To elucidate the basis of host specificity of the two S. reilianum varieties, we compared disease etiology of S. reilianum f. sp. reilianum and S. reilianum f. sp. zeae on sorghum and maize. Both varieties could penetrate and multiply in both hosts. However, red spots appeared on inoculated leaves after sorghum infection with S. reilianum f. sp. zeae. Using matrix-assisted laser desorption-ionization time of flight analysis of leaf extracts, we show that sorghum reacts with the production of the red and orange phytoalexins luteolinidin and apigeninidin upon colonization by S. reilianum f. sp. zeae but not by S. reilianum f. sp. reilianum. Using in vitro growth assays, we demonstrate that luteolinidin but not apigeninidin slows vegetative growth of both S. reilianum f. sp. zeae and S. reilianum f. sp. reilianum. However, the phytoalexin biosynthesis gene SbDFR3 is only induced in sorghum after infection with S. reilianum f. sp. zeae, as shown by quantitative real-time polymerase chain reaction. This suggests that regulation of luteolinidin biosynthesis determines infection success of S. reilianum on sorghum.

  3. Phosphorylation of a WRKY transcription factor by two pathogen-responsive MAPKs drives phytoalexin biosynthesis in Arabidopsis.

    Science.gov (United States)

    Mao, Guohong; Meng, Xiangzong; Liu, Yidong; Zheng, Zuyu; Chen, Zhixiang; Zhang, Shuqun

    2011-04-01

    Plant sensing of invading pathogens triggers massive metabolic reprogramming, including the induction of secondary antimicrobial compounds known as phytoalexins. We recently reported that MPK3 and MPK6, two pathogen-responsive mitogen-activated protein kinases, play essential roles in the induction of camalexin, the major phytoalexin in Arabidopsis thaliana. In search of the transcription factors downstream of MPK3/MPK6, we found that WRKY33 is required for MPK3/MPK6-induced camalexin biosynthesis. In wrky33 mutants, both gain-of-function MPK3/MPK6- and pathogen-induced camalexin production are compromised, which is associated with the loss of camalexin biosynthetic gene activation. WRKY33 is a pathogen-inducible transcription factor, whose expression is regulated by the MPK3/MPK6 cascade. Chromatin immunoprecipitation assays reveal that WRKY33 binds to its own promoter in vivo, suggesting a potential positive feedback regulatory loop. Furthermore, WRKY33 is a substrate of MPK3/MPK6. Mutation of MPK3/MPK6 phosphorylation sites in WRKY33 compromises its ability to complement the camalexin induction in the wrky33 mutant. Using a phospho-protein mobility shift assay, we demonstrate that WRKY33 is phosphorylated by MPK3/MPK6 in vivo in response to Botrytis cinerea infection. Based on these data, we conclude that WRKY33 functions downstream of MPK3/MPK6 in reprogramming the expression of camalexin biosynthetic genes, which drives the metabolic flow to camalexin production in Arabidopsis challenged by pathogens.

  4. Non-host disease resistance response in pea (Pisum sativum) pods: Biochemical function of DRR206 and phytoalexin pathway localization.

    Science.gov (United States)

    Seneviratne, Herana Kamal; Dalisay, Doralyn S; Kim, Kye-Won; Moinuddin, Syed G A; Yang, Hong; Hartshorn, Christopher M; Davin, Laurence B; Lewis, Norman G

    2015-05-01

    Continually exposed to potential pathogens, vascular plants have evolved intricate defense mechanisms to recognize encroaching threats and defend themselves. They do so by inducing a set of defense responses that can help defeat and/or limit effects of invading pathogens, of which the non-host disease resistance response is the most common. In this regard, pea (Pisum sativum) pod tissue, when exposed to Fusarium solani f. sp. phaseoli spores, undergoes an inducible transcriptional activation of pathogenesis-related genes, and also produces (+)-pisatin, its major phytoalexin. One of the inducible pathogenesis-related genes is Disease Resistance Response-206 (DRR206), whose role in vivo was unknown. DRR206 is, however, related to the dirigent protein (DP) family. In this study, its biochemical function was investigated in planta, with the metabolite associated with its gene induction being pinoresinol monoglucoside. Interestingly, both pinoresinol monoglucoside and (+)-pisatin were co-localized in pea pod endocarp epidermal cells, as demonstrated using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging. In addition, endocarp epidermal cells are also the site for both chalcone synthase and DRR206 gene expression. Taken together, these data indicate that both (+)-pisatin and pinoresinol monoglucoside function in the overall phytoalexin responses.

  5. EDTA a novel inducer of pisatin, a phytoalexin indicator of the non-host resistance in peas.

    Science.gov (United States)

    Hadwiger, Lee A; Tanaka, Kiwamu

    2014-12-23

    Pea pod endocarp suppresses the growth of an inappropriate fungus or non-pathogen by generating a "non-host resistance response" that completely suppresses growth of the challenging fungus within 6 h. Most of the components of this resistance response including pisatin production can be elicited by an extensive number of both biotic and abiotic inducers. Thus this phytoalexin serves as an indicator to be used in evaluating the chemical properties of inducers that can initiate the resistance response. Many of the pisatin inducers are reported to interact with DNA and potentially cause DNA damage. Here we propose that EDTA (ethylenediaminetetraacetic acid) is an elicitor to evoke non-host resistance in plants. EDTA is manufactured as a chelating agent, however at low concentration it is a strong elicitor, inducing the phytoalexin pisatin, cellular DNA damage and defense-responsive genes. It is capable of activating complete resistance in peas against a pea pathogen. Since there is also an accompanying fragmentation of pea DNA and alteration in the size of pea nuclei, the potential biochemical insult as a metal chelator may not be its primary action. The potential effects of EDTA on the structure of DNA within pea chromatin may assist the transcription of plant defense genes.

  6. EDTA a Novel Inducer of Pisatin, a Phytoalexin Indicator of the Non-Host Resistance in Peas

    Directory of Open Access Journals (Sweden)

    Lee A. Hadwiger

    2014-12-01

    Full Text Available Pea pod endocarp suppresses the growth of an inappropriate fungus or non-pathogen by generating a “non-host resistance response” that completely suppresses growth of the challenging fungus within 6 h. Most of the components of this resistance response including pisatin production can be elicited by an extensive number of both biotic and abiotic inducers. Thus this phytoalexin serves as an indicator to be used in evaluating the chemical properties of inducers that can initiate the resistance response. Many of the pisatin inducers are reported to interact with DNA and potentially cause DNA damage. Here we propose that EDTA (ethylenediaminetetraacetic acid is an elicitor to evoke non-host resistance in plants. EDTA is manufactured as a chelating agent, however at low concentration it is a strong elicitor, inducing the phytoalexin pisatin, cellular DNA damage and defense-responsive genes. It is capable of activating complete resistance in peas against a pea pathogen. Since there is also an accompanying fragmentation of pea DNA and alteration in the size of pea nuclei, the potential biochemical insult as a metal chelator may not be its primary action. The potential effects of EDTA on the structure of DNA within pea chromatin may assist the transcription of plant defense genes.

  7. Phytoalexin Induction in French Bean : Intercellular Transmission of Elicitation in Cell Suspension Cultures and Hypocotyl Sections of Phaseolus vulgaris.

    Science.gov (United States)

    Dixon, R A; Dey, P M; Lawton, M A; Lamb, C J

    1983-02-01

    Treatment of hypocotyl sections or cell suspension cultures of dwarf French bean (Phaseolus vulgaris L.) with an abiotic elicitor (denatured ribonuclease A) resulted in increased extractable activity of the enzyme l-phenylalanine ammonia-lyase. This induction could be transmitted from treated cells through a dialysis membrane to cells which were not in direct contact with the elicitor. In hypocotyl sections, induction of isoflavonoid phytoalexin accumulation was also transmitted across a dialysis membrane, although levels of insoluble, lignin-like phenolic material remained unchanged in elicitor-treated and control sections. In bean cell suspension cultures, the induction of phenylalanine ammonia-lyase in cells separated from ribonuclease-treated cells by a dialysis membrane was also accompanied by increases in the activities of chalcone synthase and chalcone isomerase, two enzymes previously implicated in the phytoalexin defense response. Such intercellular transmission of elicitation did not occur in experiments with cells treated with a biotic elicitor preparation heat-released from the cell walls of the bean pathogen Colletotrichum lindemuthianum. The results confirm and extend previous suggestions that a low molecular weight, diffusible factor of host plant origin is involved (in French bean) in the intercellular transmission of the elicitation response to abiotic elicitors.

  8. The Phytoalexin Resveratrol Ameliorates Ochratoxin A Toxicity in Human Embryonic Kidney (HEK293) Cells.

    Science.gov (United States)

    Raghubeer, Shanel; Nagiah, Savania; Phulukdaree, Alisa; Chuturgoon, Anil

    2015-12-01

    Ochratoxin A (OTA) is a nephrotoxic mycotoxin produced by Aspergillus and Penicillium fungi. It contaminates human and animal food products, and chronic exposure is associated with renal fibrosis in humans (Balkan endemic nephropathy). Resveratrol, a phytoalexin, possesses anti-cancer and antioxidant properties. We investigated the mechanism of cellular oxidative stress induced by OTA, and the effect of resveratrol in human embryonic kidney (HEK293) cells over 24 and 48 h. Cells were exposed to OTA [IC50 = 1.5 μM (24 h) and 9.4 μM (48 h) determined using MTT assay] and 25 μM resveratrol. Glutathione was quantified by luminometry and gene expression of Nrf2 and OGG1 was determined by qPCR. Protein expression of Nrf2, LonP1, SIRT3, and pSIRT1 was assessed by Western blot, DNA damage (comet assay), and intracellular reactive oxygen species (flow cytometry). At 24 h, resveratrol increased mRNA expression of the DNA repair enzyme, OGG1 (P < 0.05), whereas OTA and OTA+resveratrol significantly decreased OGG1 expression (P < 0.05). OGG1 expression increased during 48-h exposure to resveratrol and OTA+resveratrol (P < 0.05). Comet tail lengths doubled in 48-h OTA-treated cells, whereas at both time periods, OTA+resveratrol yielded shorter comet tails (P < 0.0001). During 24- and 48-h exposure, OTA, resveratrol, and OTA+resveratrol significantly decreased mRNA expression of Nrf2 (P < 0.05). Luminometry analysis of GSH revealed an increase by OTA+resveratrol for 24 and 48 h (P < 0.05 and P < 0.001, respectively). Western blot analysis showed decreased Nrf2 protein expression during 24-h exposure, but increased Nrf2 expression during 48 h. LonP1 protein expression increased during 24-h exposure to OTA (P < 0.05) and OTA+resveratrol (P < 0.0011) and during 48-h exposure to resveratrol (P < 0.0005).

  9. Cell wall integrity and high osmolarity glycerol pathways are required for adaptation of Alternaria brassicicola to cell wall stress caused by brassicaceous indolic phytoalexins.

    Science.gov (United States)

    Joubert, Aymeric; Bataille-Simoneau, Nelly; Campion, Claire; Guillemette, Thomas; Hudhomme, Piétrick; Iacomi-Vasilescu, Béatrice; Leroy, Thibault; Pochon, Stéphanie; Poupard, Pascal; Simoneau, Philippe

    2011-01-01

    Camalexin, the characteristic phytoalexin of Arabidopsis thaliana, inhibits growth of the fungal necrotroph Alternaria brassicicola. This plant metabolite probably exerts its antifungal toxicity by causing cell membrane damage. Here we observed that activation of a cellular response to this damage requires cell wall integrity (CWI) and the high osmolarity glycerol (HOG) pathways. Camalexin was found to activate both AbHog1 and AbSlt2 MAP kinases, and activation of the latter was abrogated in a AbHog1 deficient strain. Mutant strains lacking functional MAP kinases showed hypersensitivity to camalexin and brassinin, a structurally related phytoalexin produced by several cultivated Brassica species. Enhanced susceptibility to the membrane permeabilization activity of camalexin was observed for MAP kinase deficient mutants. These results suggest that the two signalling pathways have a pivotal role in regulating a cellular compensatory response to preserve cell integrity during exposure to camalexin. AbHog1 and AbSlt2 deficient mutants had reduced virulence on host plants that may, at least for the latter mutants, partially result from their inability to cope with defence metabolites such as indolic phytoalexins. This constitutes the first evidence that a phytoalexin activates fungal MAP kinases and that outputs of activated cascades contribute to protecting the fungus against antimicrobial plant metabolites. © 2010 Blackwell Publishing Ltd.

  10. Ectopic expression of Hrf1 enhances bacterial resistance via regulation of diterpene phytoalexins, silicon and reactive oxygen species burst in rice.

    Directory of Open Access Journals (Sweden)

    Wenqi Li

    Full Text Available Harpin proteins as elicitor derived from plant gram negative bacteria such as Xanthomonas oryzae pv. oryzae (Xoo, Erwinia amylovora induce disease resistance in plants by activating multiple defense responses. However, it is unclear whether phytoalexin production and ROS burst are involved in the disease resistance conferred by the expression of the harpin(Xoo protein in rice. In this article, ectopic expression of hrf1 in rice enhanced resistance to bacterial blight. Accompanying with the activation of genes related to the phytoalexin biosynthesis pathway in hrf1-transformed rice, phytoalexins quickly and consistently accumulated concurrent with the limitation of bacterial growth rate. Moreover, the hrf1-transformed rice showed an increased ability for ROS scavenging and decreased hydrogen peroxide (H(2O(2 concentration. Furthermore, the localization and relative quantification of silicon deposition in rice leaves was detected by scanning electron microscopy (SEM and energy-dispersive X-ray spectrometer (EDS. Finally, the transcript levels of defense response genes increased in transformed rice. These results show a correlation between Xoo resistance and phytoalexin production, H(2O(2, silicon deposition and defense gene expression in hrf1-transformed rice. These data are significant because they provide evidence for a better understanding the role of defense responses in the incompatible interaction between bacterial disease and hrf1-transformed plants. These data also supply an opportunity for generating nonspecific resistance to pathogens.

  11. The outer membrane protein TolC is required for phytoalexin resistance and virulence of the fire blight pathogen Erwinia amylovora.

    Science.gov (United States)

    Al-Karablieh, Nehaya; Weingart, Helge; Ullrich, Matthias S

    2009-07-01

    Erwinia amylovora causes fire blight on several plant species such as apple and pear, which produce diverse phytoalexins as defence mechanisms. An evolutionary successful pathogen thus must develop resistance mechanisms towards these toxic compounds. The E. amylovora outer membrane protein, TolC, might mediate phytoalexin resistance through its interaction with the multidrug efflux pump, AcrAB. To prove this, a tolC mutant and an acrB/tolC double mutant were constructed. The minimal inhibitory concentrations of diverse antimicrobials and phytoalexins were determined for these mutants and compared with that of a previously generated acrB mutant. The tolC and arcB/tolC mutants were considerably more susceptible than the wild type but showed similar levels as the acrB mutant. The results clearly indicated that neither TolC nor AcrAB significantly interacted with other transport systems during the efflux of the tested toxic compounds. Survival and virulence assays on inoculated apple plants showed that pathogenicity and the ability of E. amylovora to colonize plant tissue were equally impaired by mutations of tolC and acrB/tolC. Our results allowed the conclusion that TolC plays an important role as a virulence and fitness factor of E. amylovora by mediating resistance towards phytoalexins through its exclusive interaction with AcrAB.

  12. Ectopic Expression of Hrf1 Enhances Bacterial Resistance via Regulation of Diterpene Phytoalexins, Silicon and Reactive Oxygen Species Burst in Rice

    Science.gov (United States)

    Zhong, Weigong; Yang, Jie; Okada, Kazunori; Yamane, Hisakazu; Zhang, Lei; Wang, Guang; Wang, Dong; Xiao, Shanshan; Chang, Shanshan; Qian, Guoliang; Liu, Fengquan

    2012-01-01

    Harpin proteins as elicitor derived from plant gram negative bacteria such as Xanthomonas oryzae pv. oryzae (Xoo), Erwinia amylovora induce disease resistance in plants by activating multiple defense responses. However, it is unclear whether phytoalexin production and ROS burst are involved in the disease resistance conferred by the expression of the harpinXoo protein in rice. In this article, ectopic expression of hrf1 in rice enhanced resistance to bacterial blight. Accompanying with the activation of genes related to the phytoalexin biosynthesis pathway in hrf1-transformed rice, phytoalexins quickly and consistently accumulated concurrent with the limitation of bacterial growth rate. Moreover, the hrf1-transformed rice showed an increased ability for ROS scavenging and decreased hydrogen peroxide (H2O2) concentration. Furthermore, the localization and relative quantification of silicon deposition in rice leaves was detected by scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometer (EDS). Finally, the transcript levels of defense response genes increased in transformed rice. These results show a correlation between Xoo resistance and phytoalexin production, H2O2, silicon deposition and defense gene expression in hrf1-transformed rice. These data are significant because they provide evidence for a better understanding the role of defense responses in the incompatible interaction between bacterial disease and hrf1-transformed plants. These data also supply an opportunity for generating nonspecific resistance to pathogens. PMID:22970151

  13. The photoelectric displacement converter

    Science.gov (United States)

    Dragoner, Valeriu V.

    2005-02-01

    In the article are examined questions of constructing photoelectric displacement converter satisfying demands that are stated above. Converter has channels of approximate and precise readings. The approximate reading may be accomplished either by the method of reading from a code mask or by the method of the consecutive calculation of optical scale gaps number. Phase interpolator of mouar strips" gaps is determined as a precise measuring. It is shown mathematical model of converter that allow evaluating errors and operating speed of conversion.

  14. High speed data converters

    CERN Document Server

    Ali, Ahmed MA

    2016-01-01

    This book covers high speed data converters from the perspective of a leading high speed ADC designer and architect, with a strong emphasis on high speed Nyquist A/D converters. For our purposes, the term 'high speed' is defined as sampling rates that are greater than 10 MS/s.

  15. Electrical Power Converter

    NARCIS (Netherlands)

    Ferreira, J.A.

    2014-01-01

    Electrical power converter for converting electrical power of a power source connected or connectable at an input to electrical DC-power at an output, wherein between the input and the output a first circuit of submodules is provided, wherein said first circuit of submodules and the power source for

  16. Cascaded resonant bridge converters

    Science.gov (United States)

    Stuart, Thomas A. (Inventor)

    1989-01-01

    A converter for converting a low voltage direct current power source to a higher voltage, high frequency alternating current output for use in an electrical system where it is desired to use low weight cables and other circuit elements. The converter has a first stage series resonant (Schwarz) converter which converts the direct current power source to an alternating current by means of switching elements that are operated by a variable frequency voltage regulator, a transformer to step up the voltage of the alternating current, and a rectifier bridge to convert the alternating current to a direct current first stage output. The converter further has a second stage series resonant (Schwarz) converter which is connected in series to the first stage converter to receive its direct current output and convert it to a second stage high frequency alternating current output by means of switching elements that are operated by a fixed frequency oscillator. The voltage of the second stage output is controlled at a relatively constant value by controlling the first stage output voltage, which is accomplished by controlling the frequency of the first stage variable frequency voltage controller in response to second stage voltage. Fault tolerance in the event of a load short circuit is provided by making the operation of the first stage variable frequency voltage controller responsive to first and second stage current limiting devices. The second stage output is connected to a rectifier bridge whose output is connected to the input of the second stage to provide good regulation of output voltage wave form at low system loads.

  17. Phenalenone-type phytoalexins mediate resistance of banana plants (Musa spp.) to the burrowing nematode Radopholus similis.

    Science.gov (United States)

    Hölscher, Dirk; Dhakshinamoorthy, Suganthagunthalam; Alexandrov, Theodore; Becker, Michael; Bretschneider, Tom; Buerkert, Andreas; Crecelius, Anna C; De Waele, Dirk; Elsen, Annemie; Heckel, David G; Heklau, Heike; Hertweck, Christian; Kai, Marco; Knop, Katrin; Krafft, Christoph; Maddula, Ravi K; Matthäus, Christian; Popp, Jürgen; Schneider, Bernd; Schubert, Ulrich S; Sikora, Richard A; Svatoš, Aleš; Swennen, Rony L

    2014-01-01

    The global yield of bananas-one of the most important food crops-is severely hampered by parasites, such as nematodes, which cause yield losses up to 75%. Plant-nematode interactions of two banana cultivars differing in susceptibility to Radopholus similis were investigated by combining the conventional and spatially resolved analytical techniques (1)H NMR spectroscopy, matrix-free UV-laser desorption/ionization mass spectrometric imaging, and Raman microspectroscopy. This innovative combination of analytical techniques was applied to isolate, identify, and locate the banana-specific type of phytoalexins, phenylphenalenones, in the R. similis-caused lesions of the plants. The striking antinematode activity of the phenylphenalenone anigorufone, its ingestion by the nematode, and its subsequent localization in lipid droplets within the nematode is reported. The importance of varying local concentrations of these specialized metabolites in infected plant tissues, their involvement in the plant's defense system, and derived strategies for improving banana resistance are highlighted.

  18. Converting Nonclassicality into Entanglement

    Science.gov (United States)

    Killoran, N.; Steinhoff, F. E. S.; Plenio, M. B.

    2016-02-01

    Quantum mechanics exhibits a wide range of nonclassical features, of which entanglement in multipartite systems takes a central place. In several specific settings, it is well known that nonclassicality (e.g., squeezing, spin squeezing, coherence) can be converted into entanglement. In this work, we present a general framework, based on superposition, for structurally connecting and converting nonclassicality to entanglement. In addition to capturing the previously known results, this framework also allows us to uncover new entanglement convertibility theorems in two broad scenarios, one which is discrete and one which is continuous. In the discrete setting, the classical states can be any finite linearly independent set. For the continuous setting, the pertinent classical states are "symmetric coherent states," connected with symmetric representations of the group S U (K ). These results generalize and link convertibility properties from the resource theory of coherence, spin coherent states, and optical coherent states, while also revealing important connections between local and nonlocal pictures of nonclassicality.

  19. Improving Power Converter Reliability

    DEFF Research Database (Denmark)

    Ghimire, Pramod; de Vega, Angel Ruiz; Beczkowski, Szymon

    2014-01-01

    The real-time junction temperature monitoring of a high-power insulated-gate bipolar transistor (IGBT) module is important to increase the overall reliability of power converters for industrial applications. This article proposes a new method to measure the on-state collector?emitter voltage...... of a high-power IGBT module during converter operation, which may play a vital role in improving the reliability of the power converters. The measured voltage is used to estimate the module average junction temperature of the high and low-voltage side of a half-bridge IGBT separately in every fundamental...... is measured in a wind power converter at a low fundamental frequency. To illustrate more, the test method as well as the performance of the measurement circuit are also presented. This measurement is also useful to indicate failure mechanisms such as bond wire lift-off and solder layer degradation...

  20. Converting Nonclassicality into Entanglement.

    Science.gov (United States)

    Killoran, N; Steinhoff, F E S; Plenio, M B

    2016-02-26

    Quantum mechanics exhibits a wide range of nonclassical features, of which entanglement in multipartite systems takes a central place. In several specific settings, it is well known that nonclassicality (e.g., squeezing, spin squeezing, coherence) can be converted into entanglement. In this work, we present a general framework, based on superposition, for structurally connecting and converting nonclassicality to entanglement. In addition to capturing the previously known results, this framework also allows us to uncover new entanglement convertibility theorems in two broad scenarios, one which is discrete and one which is continuous. In the discrete setting, the classical states can be any finite linearly independent set. For the continuous setting, the pertinent classical states are "symmetric coherent states," connected with symmetric representations of the group SU(K). These results generalize and link convertibility properties from the resource theory of coherence, spin coherent states, and optical coherent states, while also revealing important connections between local and nonlocal pictures of nonclassicality.

  1. Thermionic photovoltaic energy converter

    Science.gov (United States)

    Chubb, D. L. (Inventor)

    1985-01-01

    A thermionic photovoltaic energy conversion device comprises a thermionic diode mounted within a hollow tubular photovoltaic converter. The thermionic diode maintains a cesium discharge for producing excited atoms that emit line radiation in the wavelength region of 850 nm to 890 nm. The photovoltaic converter is a silicon or gallium arsenide photovoltaic cell having bandgap energies in this same wavelength region for optimum cell efficiency.

  2. Differential induction of chalcone synthase mRNA activity at the onset of phytoalexin accumulation in compatible and incompatible plant-pathogen interactions.

    Science.gov (United States)

    Bell, J N; Dixon, R A; Bailey, J A; Rowell, P M; Lamb, C J

    1984-06-01

    Changes in the mRNA activity of chalcone synthase, the first enzyme of phenylpropanoid metabolism specific to flavonoid/isoflavonoid biosynthesis, have been investigated in relation to expression of the phytoalexin defense response in race-cultivar specific interactions between hypocotyls of Phaseolus vulgaris and the partially biotrophic fungus Colletotrichum lindemuthianum, causal agent of anthracnose. In an incompatible interaction (host resistant) there is an early but localized increase in chalcone synthase mRNA activity prior to the onset of accumulation of the phenylpropanoid-derived phytoalexin phaseoflin and expression of hypersensitive resistance. In contrast, in a compatible interaction (host susceptible) there is no induction of mRNA activity in the early stages of infection but rather a delayed, widespread increase during attempted lesion limitation at the onset of symptom development. The data indicate that control of phytoalexin gene expression is a key early component in the defense responses of biologically stressed cells during a race-cultivar specific host-pathogen interaction.

  3. Angiotensin-converting enzyme

    DEFF Research Database (Denmark)

    Sørensen, P G; Rømer, F K; Cortes, D

    1984-01-01

    In order to evaluate bleomycin-associated lung damage in humans, lung function parameters and serum levels of the endothelial-bound angiotensin-converting enzyme (ACE) were determined by serial measurements in 11 patients who were treated for testicular cancer. None developed clinical or radiolog......In order to evaluate bleomycin-associated lung damage in humans, lung function parameters and serum levels of the endothelial-bound angiotensin-converting enzyme (ACE) were determined by serial measurements in 11 patients who were treated for testicular cancer. None developed clinical...

  4. Identification of target genes of the bZIP transcription factor OsTGAP1, whose overexpression causes elicitor-induced hyperaccumulation of diterpenoid phytoalexins in rice cells.

    Directory of Open Access Journals (Sweden)

    Koji Miyamoto

    Full Text Available Phytoalexins are specialised antimicrobial metabolites that are produced by plants in response to pathogen attack. Momilactones and phytocassanes are the major diterpenoid phytoalexins in rice and are synthesised from geranylgeranyl diphosphate, which is derived from the methylerythritol phosphate (MEP pathway. The hyperaccumulation of momilactones and phytocassanes due to the hyperinductive expression of the relevant biosynthetic genes and the MEP pathway gene OsDXS3 in OsTGAP1-overexpressing (OsTGAP1ox rice cells has previously been shown to be stimulated by the chitin oligosaccharide elicitor. In this study, to clarify the mechanisms of the elicitor-stimulated coordinated hyperinduction of these phytoalexin biosynthetic genes in OsTGAP1ox cells, transcriptome analysis and chromatin immunoprecipitation with next-generation sequencing were performed, resulting in the identification of 122 OsTGAP1 target genes. Transcriptome analysis revealed that nearly all of the momilactone and phytocassane biosynthetic genes, which are clustered on chromosomes 4 and 2, respectively, and the MEP pathway genes were hyperinductively expressed in the elicitor-stimulated OsTGAP1ox cells. Unexpectedly, none of the clustered genes was included among the OsTGAP1 target genes, suggesting that OsTGAP1 did not directly regulate the expression of these biosynthetic genes through binding to each promoter region. Interestingly, however, several OsTGAP1-binding regions were found in the intergenic regions among and near the cluster regions. Concerning the MEP pathway genes, only OsDXS3, which encodes a key enzyme of the MEP pathway, possessed an OsTGAP1-binding region in its upstream region. A subsequent transactivation assay further confirmed the direct regulation of OsDXS3 expression by OsTGAP1, but other MEP pathway genes were not included among the OsTGAP1 target genes. Collectively, these results suggest that OsTGAP1 participates in the enhanced accumulation of

  5. Converting the reset

    NARCIS (Netherlands)

    Hoogland, J.K.; Neumann, C.D.D.; Bloch, D.

    2001-01-01

    We give a simple algorithm to incorporate the effects of resets in convertible bond prices, without having to add an extra factor to take into account the value of the reset. Furthermore we show that the effect of a notice period, and additional make-whole features, can be treated in a straightforwa

  6. An Electromagnetic Beam Converter

    DEFF Research Database (Denmark)

    2009-01-01

    The present invention relates to an electromagnetic beam converter and a method for conversion of an input beam of electromagnetic radiation having a bell shaped intensity profile a(x,y) into an output beam having a prescribed target intensity profile l(x',y') based on a further development...

  7. Definition of Power Converters

    CERN Document Server

    Bordry, F

    2015-01-01

    The paper is intended to introduce power conversion principles and to define common terms in the domain. The concept s of sources and switches are defined and classified. From the basic laws of source interconnections, a generic method of power converter synthesis is presented. Some examples illustrate this systematic method. Finally, the commutation cell and soft commuta tion are introduced and discussedd.

  8. Convertible Proxy Signcryption Scheme

    Institute of Scientific and Technical Information of China (English)

    李继国; 李建中; 曹珍富; 张亦辰

    2004-01-01

    In 1996, Mambo et al introduced the concept of proxy signature. However, proxy signature can only provide the delegated authenticity and cannot provide confidentiality. Recently, Gamage et al and Chan and Wei proposed different proxy signcryption schemes respectively, which extended the concept of proxy signature.However, only the specified receiver can decrypt and verify the validity of proxy signcryption in their schemes.To protect the receiver' s benefit in case of a later dispute, Wu and Hsu proposed a convertible authenticated encryption scheme, which carn enable the receiver to convert signature into an ordinary one that can be verified by anyone. Based on Wu and Hsu' s scheme and improved Kim' s scheme, we propose a convertible proxy signcryption scheme. The security of the proposed scheme is based on the intractability of reversing the one-way hash function and solving the discrete logarithm problem. The proposed scheme can satisfy all properties of strong proxy signature and withstand the public key substitution attack and does not use secure channel. In addition, the proposed scheme can be extended to convertible threshold proxy signcryption scheme.

  9. The Convertible Arbitrage Strategy Analyzed

    NARCIS (Netherlands)

    Loncarski, I.; Ter Horst, J.R.; Veld, C.H.

    2006-01-01

    This paper analyzes convertible bond arbitrage on the Canadian market for the period 1998 to 2004.Convertible bond arbitrage is the combination of a long position in convertible bonds and a short position in the underlying stocks. Convertible arbitrage has been one of the most successful strategies

  10. Advanced DC/DC converters

    CERN Document Server

    Luo, Fang Lin

    2003-01-01

    INTRODUCTIONHistorical ReviewMultiple Quadrant ChoppersPump CircuitsDevelopment of DC/DC Conversion TechniqueCategorize Prototypes and DC/DC Converters Family TreeVOLTAGE-LIFT CONVERTERSIntroductionSeven Self-Lift ConvertersPositive Output Luo-ConvertersNegative Output Luo-ConvertersModified Positive Output Luo-Converters Double Output Luo-ConvertersPOSITIVE OUTPUT SUPER-LIFT LUO-CONVERTERS IntroductionMain SeriesAdditional SeriesEnhanced Series Re-Enhanced Series Multiple-Enhanced Series Summary of Positive Output

  11. Induction of Systemic Resistance against Aphids by Endophytic Bacillus velezensis YC7010 via Expressing PHYTOALEXIN DEFICIENT4 in Arabidopsis.

    Science.gov (United States)

    Rashid, Md Harun-Or-; Khan, Ajmal; Hossain, Mohammad T; Chung, Young R

    2017-01-01

    Aphids are the most destructive insect pests. They suck the sap and transmit plant viruses, causing widespread yield loss of many crops. A multifunctional endophytic bacterial strain Bacillus velezensis YC7010 has been found to induce systemic resistance against bacterial and fungal pathogens of rice. However, its activity against insects attack and underlying cellular and molecular defense mechanisms are not elucidated yet. Here, we show that root drenching of Arabidopsis seedlings with B. velezensis YC7010 can induce systemic resistance against green peach aphid (GPA), Myzus persicae. Treatment of bacterial suspension of B. velezensis YC7010 at 2 × 10(7) CFU/ml to Arabidopsis rhizosphere induced higher accumulation of hydrogen peroxide, cell death, and callose deposition in leaves compared to untreated plants at 6 days after infestation of GPA. Salicylic acid, jasmonic acid, ethylene, and abscisic acid were not required to confer defense against GPA in Arabidopsis plants treated by B. velezensis YC7010. Bacterial treatment with B. velezensis YC7010 significantly reduced settling, feeding and reproduction of GPA on Arabidopsis leaves via strongly expressing senescence-promoting gene PHYTOALEXIN DEFICIENT4 (PAD4) while suppressing BOTRYTIS-INDUCED KINASE1 (BIK1). These results indicate that B. velezensis YC7010-induced systemic resistance to the GPA is a hypersensitive response mainly dependent on higher expression of PAD4 with suppression of BIK1, resulting in more accumulation of hydrogen peroxide, cell death, and callose deposition in Arabidopsis.

  12. Induction of Systemic Resistance against Aphids by Endophytic Bacillus velezensis YC7010 via Expressing PHYTOALEXIN DEFICIENT4 in Arabidopsis

    Science.gov (United States)

    Rashid, Md. Harun-Or-; Khan, Ajmal; Hossain, Mohammad T.; Chung, Young R.

    2017-01-01

    Aphids are the most destructive insect pests. They suck the sap and transmit plant viruses, causing widespread yield loss of many crops. A multifunctional endophytic bacterial strain Bacillus velezensis YC7010 has been found to induce systemic resistance against bacterial and fungal pathogens of rice. However, its activity against insects attack and underlying cellular and molecular defense mechanisms are not elucidated yet. Here, we show that root drenching of Arabidopsis seedlings with B. velezensis YC7010 can induce systemic resistance against green peach aphid (GPA), Myzus persicae. Treatment of bacterial suspension of B. velezensis YC7010 at 2 × 107 CFU/ml to Arabidopsis rhizosphere induced higher accumulation of hydrogen peroxide, cell death, and callose deposition in leaves compared to untreated plants at 6 days after infestation of GPA. Salicylic acid, jasmonic acid, ethylene, and abscisic acid were not required to confer defense against GPA in Arabidopsis plants treated by B. velezensis YC7010. Bacterial treatment with B. velezensis YC7010 significantly reduced settling, feeding and reproduction of GPA on Arabidopsis leaves via strongly expressing senescence-promoting gene PHYTOALEXIN DEFICIENT4 (PAD4) while suppressing BOTRYTIS-INDUCED KINASE1 (BIK1). These results indicate that B. velezensis YC7010-induced systemic resistance to the GPA is a hypersensitive response mainly dependent on higher expression of PAD4 with suppression of BIK1, resulting in more accumulation of hydrogen peroxide, cell death, and callose deposition in Arabidopsis. PMID:28261260

  13. Induction of two prenyltransferases for the accumulation of coumarin phytoalexins in elicitor-treated Ammi majus cell suspension cultures.

    Science.gov (United States)

    Hamerski, D; Schmitt, D; Matern, U

    1990-01-01

    Two dimethylallyl diphosphate:umbelliferone dimethylallyltransferase (prenyltransferase) activities, catalysing the 6-prenylation and the 7-O-prenylation, respectively, of umbelliferone in the course of phytoalexin synthesis, increased in Ammi majus cell suspension cultures in response to elicitor treatment. Both enzyme activities were dependent on Mg2+ or Mn2+ with significant preference for Mg2+ in the 6-prenylation reaction. Whereas dark-grown cells did not contain these activities, both prenyltransferase activities were induced rapidly by the addition of elicitor reaching a first maximum after 10-14 hr and a second maximum beyond 30 hr. Other coumarin specific, elicitor-induced enzyme activities of A. majus cells, in contrast, showed only one maximum of activity within the 50 hr experimental period, while the pattern of induction of phenylalanine ammonia-lyase activity resembled that of the prenyltransferases with maxima at ca 8 hr and 20-30 hr. Preliminary data suggest that the apparent biphasic induction of these enzyme activities is due to post-translational enzyme modifications.

  14. LongSAGE gene-expression profiling of Botrytis cinerea germination suppressed by resveratrol, the major grapevine phytoalexin.

    Science.gov (United States)

    Zheng, Chuanlin; Choquer, Mathias; Zhang, Bing; Ge, Hui; Hu, Songnian; Ma, Huiqin; Chen, Shangwu

    2011-09-01

    The ascomycetes Botrytis cinerea is one of the most studied necrotrophic phytopathogens and one of the main fungal parasites of grapevine. As a defense mechanism, grapevine produces a phytoalexin compound, resveratrol, which inhibits germination of the fungal conidium before it can penetrate the plant barriers and lead to host cell necrotrophy. To elucidate the effect of resveratrol on transcriptional regulation in B. cinerea germlings, two LongSAGE (long serial analysis of gene expression) libraries were generated in vitro for gene-expression profiling: 41 428 tags and among them, 15 665 unitags were obtained from resveratrol-treated B. cinerea germlings and 41 358 tags, among them, 16 362 unitags were obtained from non-treated B. cinerea germlings. In-silico analysis showed that about half of these unitags match known genes in the complete B. cinerea genome sequence. Comparison of unitag frequencies between libraries highlighted 110 genes that were transcriptionally regulated in the presence of resveratrol: 53 and 57 genes were significantly down- and upregulated, respectively. Manual curation of their putative functional categories showed that primary metabolism of germinating conidia appears to be markedly affected under resveratrol treatment, along with changes in other putative metabolic pathways, such as resveratrol detoxification and virulence-effector secretion, in B. cinerea germlings. We propose a hypothetical model of cross talk between B. cinerea germinating conidia and resveratrol-producing grapevine at the very early steps of infection.

  15. Microprocessor controlled static converter

    Directory of Open Access Journals (Sweden)

    Stefan Szabo

    2005-10-01

    Full Text Available This paper wants to demonstrate a way of implementing a microcontroller into an DC motor speed control loop. The static power converter is a fully controlled rectifier bridge, using standard SCR's. The bridge's control signals are supplied by the microcontroller and are phase-angle or burst types. The automation loop contains a software PI-style regulator. All the experimental results shows that this aproach is flexibile enough to be used on a large scale.

  16. DSP controlled power converter

    OpenAIRE

    Chan, CH; Pong, MH

    1995-01-01

    A digital controller is designed and implemented by a Digital Signal Processor (DSP) to replace the Pulse Width Modulator (PWM) and error amplifier compensation network in a two wheeler forward converter. The DSP controller is designed in three approaches: a) Discretization of analog controller - the design is based on the transfer function of the error amplifier compensation network. b) Digital PID controller design - the design is based on the general form of the pulse transfer function of ...

  17. SSG Wave Energy Converter

    DEFF Research Database (Denmark)

    Margheritini, Lucia; Vicinanza, Diego; Frigaard, Peter

    2008-01-01

    head hydroturbines are converting the potential energy of the stored water into power. A key to success for the SSG will be the low cost of the structure and its robustness. The construction of the pilot plant is scheduled and this paper aims to describe the concept of the SSG wave energy converter...... and the studies behind the process that leads to its construction. The pilot plant is an on-shore full scale module in 3 levels with an expected power production of 320 MWh/y in the North Sea. Location, wave climate and laboratory tests results will be used here to describe the pilot plant and its characteristics.......The SSG (Sea Slot-cone Generator) is a wave energy converter of the overtopping type. The structure consists of a number of reservoirs one on the top of each others above the mean water level, in which the water of incoming waves is stored temporary. In each reservoir, expressively designed low...

  18. Nitric Oxide Synthase-Mediated Phytoalexin Accumulation in Soybean Cotyledons in Response to the Diaporthe phaseolorum f. sp. meridionalis Elicitor1

    Science.gov (United States)

    Modolo, Luzia Valentina; Cunha, Fernando Queiroz; Braga, Márcia Regina; Salgado, Ione

    2002-01-01

    Phytoalexin biosynthesis is part of the defense mechanism of soybean (Glycine max) plants against attack by the fungus Diaporthe phaseolorum f. sp. meridionalis (Dpm), the causal agent of stem canker disease. The treatment of soybean cotyledons with Dpm elicitor or with sodium nitroprusside (SNP), a nitric oxide (NO) donor, resulted in a high accumulation of phytoalexins. This response did not occur when SNP was replaced by ferricyanide, a structural analog of SNP devoid of the NO moiety. Phytoalexin accumulation induced by the fungal elicitor, but not by SNP, was prevented when cotyledons were pretreated with NO synthase (NOS) inhibitors. The Dpm elicitor also induced NOS activity in soybean tissues proximal to the site of inoculation. The induced NOS activity was Ca2+- and NADPH-dependent and was sensitive to the NOS inhibitors NG-nitro-l-arginine methyl ester, aminoguanidine, and l-N6-(iminoethyl) lysine. NOS activity was not observed in SNP-elicited tissues. An antibody to brain NOS labeled a 166-kD protein in elicited and nonelicited cotyledons. Isoflavones (daidzein and genistein), pterocarpans (glyceollins), and flavones (apigenin and luteolin) were identified after exposure to the elicitor or SNP, although the accumulation of glyceollins and apigenin was limited in SNP-elicited compared with fungal-elicited cotyledons. NOS activity preceded the accumulation of these flavonoids in tissues treated with the Dpm elicitor. The accumulation of these metabolites was faster in SNP-elicited than in fungal-elicited cotyledons. We conclude that the response of soybean cotyledons to Dpm elicitor involves NO formation via a constitutive NOS-like enzyme that triggers the biosynthesis of antimicrobial flavonoids. PMID:12427995

  19. X-Y Converter Family

    DEFF Research Database (Denmark)

    Bhaskar, Mahajan Sagar; Sanjeevikumar, Padmanaban; Wheeler, Patrick

    2016-01-01

    A New breed of a buck boost converter, named as the XY converter family is proposed in this article. In the XY family, 16 topologies are presented which are highly suitable for renewable energy applications which require a high ratio of DC-DC converter; such as a photovoltaic multilevel inverter...... system, high voltage automotive applications and industrial drives. Compared to the traditional boost converter and existing recent converters, the proposed XY converter family has the ability to provide a higher output voltage by using less number of power devices and reactive components. Other distinct...... features of the XY converter family are i) Single control switch ii) Provide negative output voltage iii) Non-isolated topologies iv) High conversion ratio without making the use of high duty cycle and v) modular structure. XY family is compared with the recent high step-up converters and the detailed...

  20. Cinnamate:CoA ligase initiates the biosynthesis of a benzoate-derived xanthone phytoalexin in Hypericum calycinum cell cultures.

    Science.gov (United States)

    Gaid, Mariam M; Sircar, Debabrata; Müller, Andreas; Beuerle, Till; Liu, Benye; Ernst, Ludger; Hänsch, Robert; Beerhues, Ludger

    2012-11-01

    Although a number of plant natural products are derived from benzoic acid, the biosynthesis of this structurally simple precursor is poorly understood. Hypericum calycinum cell cultures accumulate a benzoic acid-derived xanthone phytoalexin, hyperxanthone E, in response to elicitor treatment. Using a subtracted complementary DNA (cDNA) library and sequence information about conserved coenzyme A (CoA) ligase motifs, a cDNA encoding cinnamate:CoA ligase (CNL) was isolated. This enzyme channels metabolic flux from the general phenylpropanoid pathway into benzenoid metabolism. HcCNL preferred cinnamic acid as a substrate but failed to activate benzoic acid. Enzyme activity was strictly dependent on the presence of Mg²⁺ and K⁺ at optimum concentrations of 2.5 and 100 mM, respectively. Coordinated increases in the Phe ammonia-lyase and HcCNL transcript levels preceded the accumulation of hyperxanthone E in cell cultures of H. calycinum after the addition of the elicitor. HcCNL contained a carboxyl-terminal type 1 peroxisomal targeting signal made up by the tripeptide Ser-Arg-Leu, which directed an amino-terminal reporter fusion to the peroxisomes. Masking the targeting signal by carboxyl-terminal reporter fusion led to cytoplasmic localization. A phylogenetic tree consisted of two evolutionarily distinct clusters. One cluster was formed by CoA ligases related to benzenoid metabolism, including HcCNL. The other cluster comprised 4-coumarate:CoA ligases from spermatophytes, ferns, and mosses, indicating divergence of the two clades prior to the divergence of the higher plant lineages.

  1. Resonant power converters

    CERN Document Server

    Kazimierczuk, Marian K

    2012-01-01

    This book is devoted to resonant energy conversion in power electronics. It is a practical, systematic guide to the analysis and design of various dc-dc resonant inverters, high-frequency rectifiers, and dc-dc resonant converters that are building blocks of many of today's high-frequency energy processors. Designed to function as both a superior senior-to-graduate level textbook for electrical engineering courses and a valuable professional reference for practicing engineers, it provides students and engineers with a solid grasp of existing high-frequency technology, while acquainting them wit

  2. Cycloidal Wave Energy Converter

    Energy Technology Data Exchange (ETDEWEB)

    Stefan G. Siegel, Ph.D.

    2012-11-30

    This program allowed further advancing the development of a novel type of wave energy converter, a Cycloidal Wave Energy Converter or CycWEC. A CycWEC consists of one or more hydrofoils rotating around a central shaft, and operates fully submerged beneath the water surface. It operates under feedback control sensing the incoming waves, and converts wave power to shaft power directly without any intermediate power take off system. Previous research consisting of numerical simulations and two dimensional small 1:300 scale wave flume experiments had indicated wave cancellation efficiencies beyond 95%. The present work was centered on construction and testing of a 1:10 scale model and conducting two testing campaigns in a three dimensional wave basin. These experiments allowed for the first time for direct measurement of electrical power generated as well as the interaction of the CycWEC in a three dimensional environment. The Atargis team successfully conducted two testing campaigns at the Texas A&M Offshore Technology Research Center and was able to demonstrate electricity generation. In addition, three dimensional wave diffraction results show the ability to achieve wave focusing, thus increasing the amount of wave power that can be extracted beyond what was expected from earlier two dimensional investigations. Numerical results showed wave cancellation efficiencies for irregular waves to be on par with results for regular waves over a wide range of wave lengths. Using the results from previous simulations and experiments a full scale prototype was designed and its performance in a North Atlantic wave climate of average 30kW/m of wave crest was estimated. A full scale WEC with a blade span of 150m will deliver a design power of 5MW at an estimated levelized cost of energy (LCOE) in the range of 10-17 US cents per kWh. Based on the new results achieved in the 1:10 scale experiments these estimates appear conservative and the likely performance at full scale will

  3. Bidirectional buck boost converter

    Science.gov (United States)

    Esser, Albert Andreas Maria

    1998-03-31

    A bidirectional buck boost converter and method of operating the same allows regulation of power flow between first and second voltage sources in which the voltage level at each source is subject to change and power flow is independent of relative voltage levels. In one embodiment, the converter is designed for hard switching while another embodiment implements soft switching of the switching devices. In both embodiments, first and second switching devices are serially coupled between a relatively positive terminal and a relatively negative terminal of a first voltage source with third and fourth switching devices serially coupled between a relatively positive terminal and a relatively negative terminal of a second voltage source. A free-wheeling diode is coupled, respectively, in parallel opposition with respective ones of the switching devices. An inductor is coupled between a junction of the first and second switching devices and a junction of the third and fourth switching devices. Gating pulses supplied by a gating circuit selectively enable operation of the switching devices for transferring power between the voltage sources. In the second embodiment, each switching device is shunted by a capacitor and the switching devices are operated when voltage across the device is substantially zero.

  4. Gallium phosphide energy converters

    Energy Technology Data Exchange (ETDEWEB)

    Sims, P.E.; Dinetta, L.C.; Goetz, M.A.

    1995-10-01

    Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp {minus}17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

  5. Manufacturing method of photoelectric converter

    Energy Technology Data Exchange (ETDEWEB)

    Yamazaki, Shunpei; Suzuki, Kunio; Fukada, Takeshi; Kanehana, Mikio

    1987-06-25

    This is a photoelectric converter wherein a photoelectromotive force is generated by utilizing the shorter wavelength side by the 1st converter and by utilizing the longer wavelength side by the 2nd converter; as a whole, wider wavelength range of light can be converted into electricity. In the 1st. converter, an electrode on the side of semi-incident surface is made transparent as well as an electrode equipped on the back of a non-mono-crystalline semiconductor. Light which passed this is introduced into the 2nd converter to generate an electromotive force. This invention especially relates with a method of forming this 2nd converter. In preparing I-type non-mono-crystalline semiconductor among the semiconductors having PIN junction, PCVD method is used by means of ECR (Electron Cyclotron Resonance) by using a hydrogen- or halogen- added Si-semiconductor instead of using expensive Ge, etc, which are common in the conventional method. (3 figs)

  6. Unity power factor converter

    Science.gov (United States)

    Wester, Gene W. (Inventor)

    1980-01-01

    A unity power factor converter capable of effecting either inversion (dc-to-dc) or rectification (ac-to-dc), and capable of providing bilateral power control from a DC source (or load) through an AC transmission line to a DC load (or source) for power flow in either direction, is comprised of comparators for comparing the AC current i with an AC signal i.sub.ref (or its phase inversion) derived from the AC ports to generate control signals to operate a switch control circuit for high speed switching to shape the AC current waveform to a sine waveform, and synchronize it in phase and frequency with the AC voltage at the AC ports, by selectively switching the connections to a series inductor as required to increase or decrease the current i.

  7. Electromagnetic wave energy converter

    Science.gov (United States)

    Bailey, R. L. (Inventor)

    1973-01-01

    Electromagnetic wave energy is converted into electric power with an array of mutually insulated electromagnetic wave absorber elements each responsive to an electric field component of the wave as it impinges thereon. Each element includes a portion tapered in the direction of wave propagation to provide a relatively wideband response spectrum. Each element includes an output for deriving a voltage replica of the electric field variations intercepted by it. Adjacent elements are positioned relative to each other so that an electric field subsists between adjacent elements in response to the impinging wave. The electric field results in a voltage difference between adjacent elements that is fed to a rectifier to derive dc output power.

  8. Production of the phytoalexins trans-resveratrol and delta-viniferin in two economy-relevant grape cultivars upon infection with Botrytis cinerea in field conditions.

    Science.gov (United States)

    Timperio, Anna Maria; D'Alessandro, Angelo; Fagioni, Marco; Magro, Paolo; Zolla, Lello

    2012-01-01

    Leaves, shoots and flowers from two different economy-relevant grape cultivars, Merlot and Cabernet Sauvignon, were examined to assess the distribution of phytoalexins upon inoculation with Botrytis cinerea at pre-bloom, bloom, and post-bloom stages. Mass spectrometric analysis evidenced considerable levels of trans-resveratrol (3,5,4'-trihydroxystilbene), albeit higher in Cabernet Sauvignon, in leaves from both grape cultivars following fungal infection at all the examined stages of development. Although both these cultivars are reported to be sensitive against fungal infections, in Cabernet Sauvignon leaves and flowers, we were also able to measure relevant quantities of the resveratrol dehydrodimer delta-viniferin. While infection by B. cinerea occurs at bloom stage, high-sensitivity of the HPLC-mass spectrometric analytic method allowed detecting measurable levels of viniferins even in early pre-bloom stages in Cabernet Sauvignon flowers and to evidence even slight resveratrol differences between the cultivars. Concordingly, Cabernet Sauvignon better responded to fungal infection. This analysis allowed us to conclude that, even when analyzing fungal infection-sensitive cultivars, the HPLC-MS method holds the sensitivity to highlight the slightest differences in the concentrations of the two phytoalexins and correlate them to different anti-fungal response potential. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  9. Integrated power electronic converters and digital control

    CERN Document Server

    Emadi, Ali; Nie, Zhong

    2009-01-01

    Non-isolated DC-DC ConvertersBuck ConverterBoost ConverterBuck-Boost ConverterIsolated DC-DC ConvertersFlyback ConverterForward ConverterPush-Pull ConverterFull-Bridge ConverterHalf-Bridge ConverterPower Factor CorrectionConcept of PFCGeneral Classification of PFC CircuitsHigh Switching Frequency Topologies for PFCApplication of PFC in Advanced Motor DrivesIntegrated Switched-Mode Power ConvertersSwitched-Mode Power SuppliesThe Concept of Integrated ConverterDefinition of Integrated Switched-Mode Power Supplies (ISMPS)Boost-Type Integrated TopologiesGeneral Structure of Boost-Type Integrated T

  10. Advanced power electronics converters PWM converters processing AC voltages

    CERN Document Server

    dos Santos, Euzeli

    2014-01-01

    This book covers power electronics, in depth, by presenting the basic principles and application details, which can be used both as a textbook and reference book.  Introduces a new method to present power electronics converters called Power Blocks Geometry. Applicable for courses focusing on power electronics, power electronics converters, and advanced power converters. Offers a comprehensive set of simulation results to help understand the circuits presented throughout the book

  11. Nanostructure Neutron Converter Layer Development

    Science.gov (United States)

    Park, Cheol (Inventor); Sauti, Godfrey (Inventor); Kang, Jin Ho (Inventor); Lowther, Sharon E. (Inventor); Thibeault, Sheila A. (Inventor); Bryant, Robert G. (Inventor)

    2016-01-01

    Methods for making a neutron converter layer are provided. The various embodiment methods enable the formation of a single layer neutron converter material. The single layer neutron converter material formed according to the various embodiments may have a high neutron absorption cross section, tailored resistivity providing a good electric field penetration with submicron particles, and a high secondary electron emission coefficient. In an embodiment method a neutron converter layer may be formed by sequential supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In another embodiment method a neutron converter layer may be formed by simultaneous supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In a further embodiment method a neutron converter layer may be formed by in-situ metalized aerogel nanostructure development.

  12. Impedance source power electronic converters

    CERN Document Server

    Liu, Yushan; Ge, Baoming; Blaabjerg, Frede; Ellabban, Omar; Loh, Poh Chiang

    2016-01-01

    Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key features: Comprehensive analysis of the impedance source converter/inverter topologies, including typical topologies and derived topologies. Fully explains the design and control techniques of impedance source converters/inverters, including hardware design and control parameter design for corresponding control methods. Presents the latest power conversion solutions that aim to advance the role of pow...

  13. A thermochemical energy converter

    Energy Technology Data Exchange (ETDEWEB)

    Toyeguti, K.; Indzima, T.

    1982-08-09

    Mercury is used as the active mass of the anode in the converter and 0/sub 2/ is used as the active cathode material. The reaction of Mercury + 1/2 0/sub 2/-Hg0 occurs with a discharge. With heating to 500/sup 0/C the regeneration of the Mercury, Hg0 yields Mercury + 1/2 0/sub 2/, occurs. The device for performing the thermochenical conversion of energy contains an element body, an oxygen chamber, an oxygen electrode, a chamber with an alkaline liquid electrolyte, a separator, an auxiliary separator, an electrode and a chamber with the Mercury. The thermochemical reaction occurs in the reactor to which the Hg0 is transported along a pipe which has a refrigerator and a valve. The Mercury is fed into the element from a reservoir. The Mercury reduced in the reactor and in a reaction tower is fed into it through a closed cycle. The bellows is connected with the reactor by a pipe with a refrigerator. Through it the 0/sub 2/ goes in a closed cycle to the chamber. The current forming reactions are Hg + 20H-anion yields Hg0 + H/sub 2/0 + 2e and 1/2 0/sub 2/ + H/sub 2/0 + 2e yields 20H-anion. The voltage on the outleads of the element is approximately 0.3 volts.

  14. DC to DC converters: operation; Hacheurs: fonctionnement

    Energy Technology Data Exchange (ETDEWEB)

    Bernot, F. [Ecole d' Ingenieurs de Tours, 37 (France)

    2002-05-01

    This article deals with pulse width modulation (PWM) and pulse position modulation (PPM) DC to DC converters. A tri-phase PWM converter is made of 6 simple DC/DC converters grouped together into 3 reversible converters of the same type: 1 - single-quadrant voltage lowering converters (hydraulic analogy, study with ideal elements, full scheme with input and output filters); 2 - single-quadrant voltage raising converters (hydraulic analogy, operation); 3 - two quadrants reversible converters (structure construction, quadrants of operation, reversible converter connected to a DC motor); 4 - four-quadrants reversible converters; 5 - other converters structure (current converters and converters with intermediate storage, asymmetrical converters, converters with capacitive storage, insulated converters, resonating converters, status); 6 - conclusion. (J.S.)

  15. Proposed electromagnetic wave energy converter

    Science.gov (United States)

    Bailey, R. L.

    1973-01-01

    Device converts wave energy into electric power through array of insulated absorber elements responsive to field of impinging electromagnetic radiation. Device could also serve as solar energy converter that is potentially less expensive and fragile than solar cells, yet substantially more efficient.

  16. Impedance Source Power Electronic Converters

    DEFF Research Database (Denmark)

    Liu, Yushan; Abu-Rub, Haitham; Ge, Baoming

    Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable...... and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key...... control methods. Presents the latest power conversion solutions that aim to advance the role of power electronics into industries and sustainable energy conversion systems. Compares impedance source converter/inverter applications in renewable energy power generation and electric vehicles as well...

  17. In silico study of interaction between rice proteins enhanced disease susceptibility 1 and phytoalexin deficient 4, the regulators of salicylic acid signalling pathway.

    Science.gov (United States)

    Singh, Indra; Shah, Kavita

    2012-07-01

    Enhanced disease susceptibility 1 (EDS1), a plant-specific protein has homology with the eukaryotic lipase in their N-terminal halves and a unique domain at its C-termini. EDS1 is known to be an important regulator of biotic stress and an essential component of basal immunity. EDS1 interacts with its positive co-regulator phytoalexin deficient 4 (PAD4), resulting in mobilization of the salicylic acid defence pathway. Limited information regarding this interaction in rice is available. To study this interaction, a model of EDS1 and PAD4 proteins from rice was generated and validated with Accelrys DS software version 3.1 using bioinformatics interface. The in silico docking between the two proteins showed a significant protein-protein interaction between rice EDS1 and PAD4, suggesting that they form a dimeric protein complex, which, similar to that in Arabidopsis, is perhaps also important for triggering the salicylic acid signalling pathway in plants.

  18. In silico study of interaction between rice proteins enhanced disease susceptibility 1 and phytoalexin deficient 4, the regulators of salicylic acid signalling pathway

    Indian Academy of Sciences (India)

    Indra Singh; Kavita Shah

    2012-07-01

    Enhanced disease susceptibility 1 (EDS1), a plant-specific protein has homology with the eukaryotic lipase in their N-terminal halves and a unique domain at its C-termini. EDS1 is known to be an important regulator of biotic stress and an essential component of basal immunity. EDS1 interacts with its positive co-regulator phytoalexin deficient 4 (PAD4), resulting in mobilization of the salicylic acid defence pathway. Limited information regarding this interaction in rice is available. To study this interaction, a model of EDS1 and PAD4 proteins from rice was generated and validated with Accelrys DS software version 3.1 using bioinformatics interface. The in silico docking between the two proteins showed a significant protein–protein interaction between rice EDS1 and PAD4, suggesting that they form a dimeric protein complex, which, similar to that in Arabidopsis, is perhaps also important for triggering the salicylic acid signalling pathway in plants.

  19. Radiation tolerant power converter controls

    CERN Document Server

    Todd, B; King, Q; Uznanski, S

    2012-01-01

    The Large Hadron Collider (LHC) at the European Organisation for Nuclear Research (CERN) is the world's most powerful particle collider. The LHC has several thousand magnets, both warm and super-conducting, which are supplied with current by power converters. Each converter is controlled by a purpose-built electronic module called a Function Generator Controller (FGC). The FGC allows remote control of the power converter and forms the central part of a closed-loop control system where the power converter voltage is set, based on the converter output current and magnet-circuit characteristics. Some power converters and FGCs are located in areas which are exposed to beam-induced radiation. There are numerous radiation induced effects, some of which lead to a loss of control of the power converter, having a direct impact upon the accelerator's availability. Following the first long shut down (LS1), the LHC will be able to run with higher intensity beams and higher beam energy. This is expected to lead to signifi...

  20. Power converter simulation and analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ghazy, M.A.

    1989-01-01

    There has been a great deal of progress made in computer aided design and analysis in the power electronic field. Many of the simulation packages are inefficient and time consuming in simulating switching converters. This thesis proposes an efficient, simple, general simulation approach to simulate any power converter with less computation time and space requirements on computer. In this approach the equations of power converters are formulated using network topology. In this thesis several procedures have been explained for the steady-state computation of power electronic circuits. Also, the steady-state analyses have been accomplished by a new technique called Fourier series method. For a complete system consisting of converters, filters, and electric machines, the simulation is complicated if a frequency domain technique is used. This thesis introduces a better technique which decouples the system into subsystems and simulates it in the time domain. The design of power converters using optimization techniques is presented in this thesis. Finally, the theory of Variable Structured Systems has been applied to power converters. Sliding mode control for DC-DC and DC-AC power converters is introduced as a tool to accomplish desired characteristics.

  1. Nicotiana benthamiana calreticulin 3a is required for the ethylene-mediated production of phytoalexins and disease resistance against oomycete pathogen Phytophthora infestans.

    Science.gov (United States)

    Matsukawa, Mizuki; Shibata, Yusuke; Ohtsu, Mina; Mizutani, Aki; Mori, Hitoshi; Wang, Ping; Ojika, Makoto; Kawakita, Kazuhito; Takemoto, Daigo

    2013-08-01

    Mature Nicotiana benthamiana shows strong resistance to the potato late blight pathogen Phytophthora infestans. By screening using virus-induced random gene silencing, we isolated a gene for plant-specific calreticulin NbCRT3a as a required gene for resistance of N. benthamiana against P. infestans. NbCRT3a encodes an endoplasmic reticulum quality-control (ERQC) chaperone for the maturation of glycoproteins, including glycosylated cell-surface receptors. NbCRT3a-silenced plants showed no detectable growth defects but resistance to P. infestans was significantly compromised. Defense responses induced by the treatment with INF1 (a secretory protein of P. infestans), such as production of reactive oxygen species and accumulation of phytoalexins, were suppressed in NbCRT3a-silenced N. benthamiana. Expression of an ethylene-regulated gene for phytoalexin biosynthesis, NbEAS, was reduced in NbCRT3a-silenced plants, whereas the expression of salicylic acid-regulated NbPR-1a was not affected. Consistently, induction of ethylene production by INF1 was suppressed in NbCRT3a-silenced plants. Resistance reactions induced by a hyphal wall components elicitor prepared from P. infestans were also impaired in NbCRT3a-silenced plants. However, cell death induced by active mitogen-activated protein kinase kinase (NbMEK2(DD)) was not affected by the silencing of NbCRT3a. Thus, NbCRT3a is required for the initiation of resistance reactions of N. benthamiana in response to elicitor molecules derived from P. infestans.

  2. PWM DC/DC Converter

    OpenAIRE

    Chen, Juan

    2008-01-01

    This report is the result of a Master Thesis work done at Seaward Electronics Inc. in Beijing, China from June to December in 2007. The main goal for this thesis is to verify and improve the performance of Honey-PWM DC-DC converter, which has been fabricated by a standard 0.6um CMOS processes. The project was started with studying of Buck converter structure. After the understanding of the converter structure, the project goes in to the analyses phase for each sub-cells, including the theory,...

  3. Laser system with wavelength converter

    DEFF Research Database (Denmark)

    2012-01-01

    The present invention relates to an apparatus comprising a diode laser (10) providing radiation in a first wavelength interval, a radiation conversion unit (12) having an input and an output, the radiation converter configured to receive the radiation in the first wavelength interval from the diode...... laser at the input, the radiation conversion unit configured to convert the radiation in the first wavelength interval to radiation in a second wavelength interval and the output configured to output the converted radiation, the second wavelength interval having one end point outside the first...... wavelength interval. Further, the invention relates to a method of optically pumping a target laser (14) in a laser system, the laser system comprising a laser source providing radiation at a first frequency, the laser source being optically connected to an input of a frequency converter, the frequency...

  4. Time-to-digital converters

    CERN Document Server

    Henzler, Stephan

    2010-01-01

    This text covers the fundamentals of time-to-digital converters on analog and digital conversion principles. It includes a theoretical investigation into quantization, linearity, noise and variability, and it details a range of advanced TDC architectures.

  5. Boron nitride converted carbon fiber

    Science.gov (United States)

    Rousseas, Michael; Mickelson, William; Zettl, Alexander K.

    2016-04-05

    This disclosure provides systems, methods, and apparatus related to boron nitride converted carbon fiber. In one aspect, a method may include the operations of providing boron oxide and carbon fiber, heating the boron oxide to melt the boron oxide and heating the carbon fiber, mixing a nitrogen-containing gas with boron oxide vapor from molten boron oxide, and converting at least a portion of the carbon fiber to boron nitride.

  6. Photoelectric converters with quantum coherence

    OpenAIRE

    Su, Shan-He; Sun, Chang-Pu; Li, Sheng-Wen; Chen, Jin-Can

    2016-01-01

    Photon impingement is capable of liberating electrons in electronic devices and driving the electron flux from the lower chemical potential to higher chemical potential. Previous studies hinted that the thermodynamic efficiency of a nano-sized photoelectric converter at maximum power is bounded by the Curzon-Ahlborn efficiency. In this study, we apply quantum effects to design a photoelectric converter based on a three-level quantum dot (QD) interacting with fermionic baths and photons. We sh...

  7. Radiation tolerant power converter controls

    Science.gov (United States)

    Todd, B.; Dinius, A.; King, Q.; Uznanski, S.

    2012-11-01

    The Large Hadron Collider (LHC) at the European Organisation for Nuclear Research (CERN) is the world's most powerful particle collider. The LHC has several thousand magnets, both warm and super-conducting, which are supplied with current by power converters. Each converter is controlled by a purpose-built electronic module called a Function Generator Controller (FGC). The FGC allows remote control of the power converter and forms the central part of a closed-loop control system where the power converter voltage is set, based on the converter output current and magnet-circuit characteristics. Some power converters and FGCs are located in areas which are exposed to beam-induced radiation. There are numerous radiation induced effects, some of which lead to a loss of control of the power converter, having a direct impact upon the accelerator's availability. Following the first long shut down (LS1), the LHC will be able to run with higher intensity beams and higher beam energy. This is expected to lead to significantly increased radiation induced effects in materials close to the accelerator, including the FGC. Recent radiation tests indicate that the current FGC would not be sufficiently reliable. A so-called FGClite is being designed to work reliably in the radiation environment in the post-LS1 era. This paper outlines the concepts of power converter controls for machines such as the LHC, introduces the risks related to radiation and a radiation tolerant project flow. The FGClite is then described, with its key concepts and challenges: aiming for high reliability in a radiation field.

  8. Transformerless dc-Isolated Converter

    Science.gov (United States)

    Rippel, Wally E.

    1987-01-01

    Efficient voltage converter employs capacitive instead of transformer coupling to provide dc isolation. Offers buck/boost operation, minimal filtering, and low parts count, with possible application in photovoltaic power inverters, power supplies and battery charges. In photovoltaic inverter circuit with transformerless converter, Q2, Q3, Q4, and Q5 form line-commutated inverter. Switching losses and stresses nil because switching performed when current is zero.

  9. Wave energy converter test application

    OpenAIRE

    Hottola, Niko

    2016-01-01

    This thesis was made for wave energy company Wello Oy. Given assignment was to find the suitable generator and frequency converter for a wave energy converter test application. The primary objective was to find a suitable generator for direct drive, in order to avoid the weight of the test application rising too high. In this thesis the possible machine types for test application are presented and what are their advenatages and disadvantages. In addition, the operation of the frequency co...

  10. Radiation effects on DC-DC Converters

    Science.gov (United States)

    Zhang, Dexin; Attia, John O.; Kankam, Mark D. (Technical Monitor)

    2000-01-01

    DC-DC switching converters are circuits that can be used to convert a DC voltage of one value to another by switching action. They are increasing being used in space systems. Most of the popular DC-DC switching converters utilize power MOSFETs. However power MOSFETs, when subjected to radiation, are susceptible to degradation of device characteristics or catastrophic failure. This work focuses on the effects of total ionizing dose on converter performance. Four fundamental switching converters (buck converter, buck-boost converter, cuk converter, and flyback converter) were built using Harris IRF250 power MOSFETs. These converters were designed for converting an input of 60 volts to an output of about 12 volts with a switching frequency of 100 kHz. The four converters were irradiated with a Co-60 gamma source at dose rate of 217 rad/min. The performances of the four converters were examined during the exposure to the radiation. The experimental results show that the output voltage of the converters increases as total dose increases. However, the increases of the output voltage were different for the four different converters, with the buck converter and cuk converter the highest and the flyback converter the lowest. We observed significant increases in output voltage for cuk converter at a total dose of 24 krad (si).

  11. Binary/BCD-to-ASCII data converter

    Science.gov (United States)

    Miller, A. J.

    1977-01-01

    Converter inputs multiple precision binary words, converts data to multiple precision binary-coded decimal, and routes data back to computer. Converter base can be readily changed without need for new gate structure for each base changeover.

  12. PWM Converter Power Density Barriers

    Science.gov (United States)

    Kolar, Johann W.; Drofenik, Uwe; Biela, Juergen; Heldwein, Marcelo; Ertl, Hans; Friedli, Thomas; Round, Simon

    Power density of power electronic converters has roughly doubled every 10 years since 1970. Behind this trajectory is the continuous advancement of power semiconductor devices, which has increased the converter switching frequencies by a factor of 10 every decade. However, today's cooling concepts and passive components are major barriers for a continuation of this trend. To identify such technological barriers, this paper investigates the volume of the cooling system and passive components as a function of the switching frequency for power electronic converters and determines the switching frequency that minimizes the total volume. A power density limit of 28kW/dm3 at 300kHz is calculated for an isolated DC-DC converter, 44kW/dm3 at 820kHz for a three-phase unity power factor PWM rectifier, and 26kW/dm3 at 21kHz for a sparse matrix converter. For single-phase AC-DC conversion a general limit of 35kW/dm3 results from the DC link capacitor. These power density limits highlight the need to broaden the scope of power electronics research to include cooling systems, high frequency electromagnetics, interconnection and packaging technology, and multi-domain modelling and simulation to ensure further advancement along the power density trajectory.

  13. Fungus-Elicited Metabolites from Plants as an Enriched Source for New Leishmanicidal Agents: Antifungal Phenyl-Phenalenone Phytoalexins from the Banana Plant (Musa acuminata) Target Mitochondria of Leishmania donovani Promastigotes

    Science.gov (United States)

    Luque-Ortega, Juan Román; Martínez, Silvia; Saugar, José María; Izquierdo, Laura R.; Abad, Teresa; Luis, Javier G.; Piñero, José; Valladares, Basilio; Rivas, Luis

    2004-01-01

    Two antifungal phenyl-phenalenone phytoalexins isolated from the banana plant (Musa acuminata) elicited with the fungus Fusarium oxysporum, together with a methoxy derivative of one of them and two epoxide precursors of their chemical synthesis, were tested for leishmanicidal activity on Leishmania donovani promastigotes and L. infantum amastigotes. Drugs inhibited proliferation of both forms of the parasite with a 50% lethal concentration range between 10.3 and 68.7 μg/ml. Their lethal mechanism was found linked to the respiratory chain by a systematic approach, including electron microscopy, measurement of the oxygen consumption rate on digitonin-permeabilized promastigotes, and enzymatic assays on a mitochondrial enriched fraction. Whereas the whole set of compounds inhibited the activity of fumarate reductase in the mitochondrial fraction (50% effective concentration [EC50] between 33.3 and 78.8 μg/ml) and on purified enzyme (EC50 = 53.3 to 115 μg/ml), inhibition for succinate dehydrogenase was only observed for the two phytoalexins with the highest leishmanicidal activity: anigorufone and its natural analogue 2-methoxy-9-phenyl-phenalen-1-one (EC50 = 33.5 and 59.6 μg/ml, respectively). These results provided a new structural motif, phenyl-phenalenone, as a new lead for leishmanicidal activity, and support the use of plant extracts enriched in antifungal phytoalexins, synthesized under fungal challenge, as a more rational and effective strategy to screen for new plant leishmanicidal drugs. PMID:15105102

  14. Post combustion in converter steelmaking

    Energy Technology Data Exchange (ETDEWEB)

    Oghbasilasie, H.; Holappa, L.

    1997-12-31

    The purpose of this work is to study the fundamentals of post combustion and the effect of different process parameters on the post combustion ratio (PCR) and heat transfer efficiency (HTE) in converter steelmaking process. The PCR and HTE have been determined under normal operating conditions. Trials assessed the effect of lance height, vessel volume, foaming slag and pellet additions on PCR and HTE. Based on enthalpy considerations, post combustion of CO gas is regarded as one of the most effective means of increasing the heat supply to the BOP. The thermodynamic study of gas-metal-slag reactions gives the limiting conditions for post combustion inside the converter reactor. Different process parameters influencing both thermodynamic equilibria and kinetic conditions can greatly affect the post combustion ratio. Different features of converter processes as well smelting reduction processes utilizing post combustion have been reviewed. (orig.) SULA 2 Research Programme; 26 refs.

  15. Stirling Converters For Solar Power

    Science.gov (United States)

    Shaltens, Richard K.; Schreiber, Jeffrey G.

    1993-01-01

    Two designs expected to meet long-term goals for performance and cost. Proposed for advanced systems to convert solar thermal power to electrical power. Each system, designed to operate with 11-m-diameter paraboloidal reflector, includes solar-energy receiver, liquid-metal heat-transport subsystem, free-piston Stirling engine, cooling subsystem, alternator or generator coupled directly or indirectly to commercial electric-power system, and control and power-conditioning circuitry. System converts approximately 75 kW of input solar thermal power falling on collector to about 25 kW of output electrical power.

  16. Simplified design of data converters

    CERN Document Server

    Lenk, John

    1997-01-01

    Simplified Design of Data Converters shows how to design and experiment with data converters, both analog-to-digital and digital to analog. The design approach here is the same one used in all of John Lenk's best-selling books on simplified and practical design. Throughout the book, design problems start with guidelines for selecting all components on a trial-value basis, assuming a specific design goal and set of conditions. Then, using the guideline values in experimental circuits, the desired results are produced by varying the experimental component values, if needed.If you are a w

  17. Design and Control for the Buck-Boost Converter Combining 1-Plus-D Converter and Synchronous Rectified Buck Converters

    OpenAIRE

    2015-01-01

    In this paper, a design and control for the buck-boost converter, i.e., 1-plus-D converter with a positive output voltage, is presented, which combines the 1-plus-D converter and the synchronous rectified (SR) buck converter. By doing so, the problem in voltage bucking of the 1-plus-D converter can be solved, thereby increasing the application capability of the 1-plus-D converter. Since such a converter operates in continuous conduction mode inherently, it possesses the nonpulsating output cu...

  18. AC-DC PFC Converter Using Combination of Flyback Converter and Full-bridge DC-DC Converter

    Directory of Open Access Journals (Sweden)

    Moh. Zaenal Efendi

    2014-06-01

    Full Text Available This paper presents a combination of power factor correction converter using Flyback converter and Full-bridge dc-dc converter in series connection. Flyback converter is operated in discontinuous conduction mode so that it can serve as a power factor correction converter and meanwhile Full-bridge dc-dc converter is used for dc regulator. This converter system is designed to produce a 86 Volt of output voltage and 2 A of output current. Both simulation and experiment results show that the power factor of this converter achieves up to 0.99 and meets harmonic standard of IEC61000-3-2. Keywords: Flyback Converter, Full-bridge DC-DC Converter, Power Factor Correction.

  19. Rapid accumulation and metabolism of polyphosphoinositol and its possible role in phytoalexin biosynthesis in yeast elicitor-treated Cupressus lusitanica cell cultures.

    Science.gov (United States)

    Zhao, Jian; Guo, YingQing; Kosaihira, Atsushi; Sakai, Kokki

    2004-05-01

    Inositol 1,4,5-trisphosphate [Ins(1,4,5)P(3)] rapidly accumulates in elicited Cupressus lusitanica Mill. cultured cells by 4- to 5-fold over the control, and then it is metabolized. Correspondingly, phospholipase C (PLC) activity toward phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)] is stimulated to high levels by the elicitor and then decreases whereas Ins(1,4,5)P(3) phosphatase activity declines at the beginning of elicitation and increases later. These observations indicate that elicitor-induced biosynthesis and dephosphorylation of Ins(1,4,5)P(3) occur simultaneously and that the Ins(1,4,5)P(3) level may be regulated by both PtdIns(4,5)P(2)-PLC and Ins(1,4,5)P(3) phosphatases. Studies on the properties of PLC and Ins(1,4,5)P(3) phosphatases indicate that PLC activity toward PtdIns(4,5)P(2) was optimal at a lower Ca(2+) concentration than activity toward phosphatidylinositol whereas Ins(1,4,5)P(3) phosphatase activity is inhibited by high Ca(2+) concentration. This suggests that Ins(1,4,5)P(3) biosynthesis and degradation may be regulated by free cytosolic Ca(2+). In addition, a relationship between Ins(1,4,5)P(3) signaling and accumulation of a phytoalexin (beta-thujaplicin) is suggested because inhibition or promotion of Ins(1,4,5)P(3) accumulation by neomycin or LiCl affects elicitor-induced production of beta-thujaplicin. Moreover, ruthenium red inhibits elicitor-induced accumulation of beta-thujaplicin while thapsigargin alone induces beta-thujaplicin accumulation. These results suggest that Ca(2+) released from intracellular calcium stores may mediate elicitor-induced accumulation of beta-thujaplicin via an Ins(1,4,5)P(3) signaling pathway, since it is widely accepted that Ins(1,4,5)P(3) can mobilize Ca(2+) from intracellular stores. This work demonstrates an elicitor-triggered Ins(1,4,5)P(3) turnover, defines its enzymatic basis and regulation, and suggests a role for Ins(1,4,5)P(3) in elicitor-induced phytoalexin accumulation via a Ca(2

  20. XML Docbook to Mediawiki Converter

    Directory of Open Access Journals (Sweden)

    Maria Chiara Pievatolo

    2013-05-01

    Full Text Available A Perl script, based on the work of Stefano Selleri, to migrate XML-Docbook 4.X documents to Wiki markup. I added some lines to meet my need to convert my Kant translations from Docbook to MediaWiki. A sample of the output can be...

  1. Charge-pump voltage converter

    Science.gov (United States)

    Brainard, John P.; Christenson, Todd R.

    2009-11-03

    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  2. High-Performance Data Converters

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper

    Novel techniques for multi-bit oversampled data conversion are described. State-of-the-art oversampled data converters are analyzed, leading to the conclusion that their performance is limited mainly by low-resolution signal representation. To increase the resolution, high-performance, high...

  3. Indução de fitoalexinas em cotilédones de soja em resposta a derivados de folhas de pitangueira Induction of phytoalexins in cotyledons of soybean in response to the derivatives of leaf surinan cherry

    Directory of Open Access Journals (Sweden)

    Sergio Miguel Mazaro

    2008-10-01

    Full Text Available A demanda mundial por alimentos isentos de agrotóxicos tem impulsionado a pesquisa para a busca de métodos alternativos ao controle de patógenos em plantas. A ativação dos mecanismos de defesa com o uso de indutores vem demonstrando ser uma alternativa viável e promissora. O uso de extratos de plantas medicinais tem demonstrado capacidade para induzir a produção de fitoalexinas, como um mecanismo de defesa em plantas tratadas. O objetivo deste trabalho foi verificar o potencial da planta Eugenia uniflora L. (pitangueira em induzir fitoalexinas em cotilédones de soja (Glycine max. Os derivados de extrato alcoólico, infusão, maceração e decocção, obtidos de folhas de pitangueira, foram usados nas concentrações de 0,1; 1; 10 e 40%, além de óleo essencial. Água foi utilizada como controle e quitosana (1% como indutor de referência. Os preparados de pitangueira apresentaram capacidade de indução das fitoalexinas gliceolinas em cotilédones de soja, respondendo ao aumento das concentrações dos preparados. O óleo essencial apresentou destacável efeito na indução de fitoalexinas, sendo superior aos demais preparados. Quitosana induziu fitoalexinas em cotilédones de soja e pode ser utilizado em estudos similares como um indutor de referência.The worldwide demand for food without pesticides has stimulated the research on alternative methods to control pathogens in plants. The activation of defense mechanisms by inductors seems a viable and promising alternative. The use of medicinal plants extracts has demonstrated capacity to induce the production of phytoalexins, as a mechanism of defense in treated plants. The objective of this research was to verify the potential of Eugenia uniflora L. (surinan cherry to induce phytoalexins in cotyledons of soybean (Glycine max. The derivatives alcoholic extract, infusion, maceration and decoction, obtained of surinan cherry were used in the concentrations of 0.1; 1; 10 and 40%, beyond

  4. Bidirectional dc-to-dc Power Converter

    Science.gov (United States)

    Griesbach, C. R.

    1986-01-01

    Solid-state, series-resonant converter uses high-voltage thyristors. Converter used either to convert high-voltage, low-current dc power to lowvoltage, high current power or reverse. Taking advantage of newly-available high-voltage thyristors to provide better reliability and efficiency than traditional converters that use vacuum tubes as power switches. New converter essentially maintenance free and provides greatly increased mean time between failures. Attractive in industrial applications whether or not bidirectional capability is required.

  5. Parametric study of laser photovoltaic energy converters

    Science.gov (United States)

    Walker, G. H.; Heinbockel, J. H.

    1987-01-01

    Photovoltaic converters are of interest for converting laser power to electrical power in a space-based laser power system. This paper describes a model for photovoltaic laser converters and the application of this model to a neodymium laser silicon photovoltaic converter system. A parametric study which defines the sensitivity of the photovoltaic parameters is described. An optimized silicon photovoltaic converter has an efficiency greater than 50 percent for 1000 W/sq cm of neodymium laser radiation.

  6. Systemic Induction of the Defensin and Phytoalexin Pisatin Pathways in Pea (Pisum sativum against Aphanomyces euteiches by Acetylated and Nonacetylated Oligogalacturonides

    Directory of Open Access Journals (Sweden)

    Sameh Selim

    2017-06-01

    Full Text Available Oligogalacturonides (OGs are known for their powerful ability to stimulate the plant immune system but little is known about their mode of action in pea (Pisum sativum. In the present study, we investigated the elicitor activity of two fractions of OGs, with polymerization degrees (DPs of 2–25, in pea against Aphanomyces euteiches. One fraction was nonacetylated (OGs − Ac whereas the second one was 30% acetylated (OGs + Ac. OGs were applied by injecting the upper two rachises of the plants at three- and/or four-weeks-old. Five-week-old roots were inoculated with 105 zoospores of A. euteiches. The root infection level was determined at 7, 10 and 14 days after inoculation using the quantitative real-time polymerase chain reaction (qPCR. Results showed significant root infection reductions namely 58, 45 and 48% in the plants treated with 80 µg OGs + Ac and 59, 56 and 65% with 200 µg of OGs − Ac. Gene expression results showed the upregulation of genes involved in the antifungal defensins, lignans and the phytoalexin pisatin pathways and a priming effect in the basal defense, SA and ROS gene markers as a response to OGs. The reduction of the efficient dose in OGs + Ac is suggesting that acetylation is necessary for some specific responses. Our work provides the first evidence for the potential of OGs in the defense induction in pea against Aphanomyces root rot.

  7. Antibacterial, antifungal and phytoalexins induction activities of hydrolates of medicinal plants/ Atividades antibacteriana, antifúngica e indutora de fitoalexinas de hidrolatos de plantas medicinais

    Directory of Open Access Journals (Sweden)

    Maria Eugênia Silva Cruz

    2007-07-01

    Full Text Available The aim of this work was to evaluate the antifungical, antibacterial and phytoalexins elicitors activities of hydrolates, for using in the alternative control of plant diseases. The hydrolates of Helietta apiculata (HA, Conyza canadensis (CC and Cymbopogon nardus (CN were used in the concentrations of 1, 5, 10, 15, 20 and 25%. In the phytoalexins assay, sorghum etiolated mesocotyls were used. The antibacterial effect was evaluated on the growth of the bacterium Xanthomonas campestris pv. campestris in liquid nutrient medium and antibiotic (oxytetraciclin 22.5 mg/L + streptomycin 225 mg/L was used as control treatment. The antifungical effect was evaluated on the micelial growth, esporulation, conidia germination and development of germinative tubes of Alternaria brassicae. The fungicide azoxystrobin (0.08 g a.i./ L was used as control treatment. There was increment in the phytoalexins synthesis with the increase in hydrolates concentration. The better result was obtained with CN that promoted increase 4.3 times larger in relation to the value of the control treatment with water, followed by HA (2.5 times and CC (2.1 times. Similar results were obtained to the antibacterial activity with the following inhibition results (% in the development of the bacterium: CN: 29.8, HA: 14.9, CC: 14.6 and antibiotic: 97.7. The main antifungical effect was observed on the development of the germinative tubes. Hydrolates of CC and HA showed inhibition of up to 69.2 and 56.2%, respectively, being similar to the fungicide azoxystrobin. The hydrolate of CN did not show antifungical effect. These results indicate the presence of phytoalexins elicitors, and antibacterial and antifungical compounds in those hydrolates, however in low concentrations.O objetivo do trabalho foi avaliar a atividade como antifúngico, antibacteriano e indutor da produção de fitoalexinas dos hidrolatos de Helietta apiculata (canela-de-veado (HA, Conyza canadensis (buva (CC e Cymbopogon

  8. Novel process of fermenting black soybean [Glycine max (L.) Merrill] yogurt with dramatically reduced flatulence-causing oligosaccharides but enriched soy phytoalexins.

    Science.gov (United States)

    Feng, Shengbao; Saw, Chin Lee; Lee, Yuan Kun; Huang, Dejian

    2008-11-12

    Black soybeans [Glycine max (L.) Merrill] were germinated under fungal stress with food grade R. oligosporus for 3 days and were homogenized and fermented with lactic acid bacteria (LAB) to produce soy yogurt. Fungal stress led to the generation of oxylipins [oxooctadecadienoic acids (KODES) isomers and their respective glyceryl esters] and glyceollins--a type of phytoalexins unique to soybeans. In soy yogurt, the concentrations of total KODES and total glyceollins were 0.678 mg/g (dry matter) and 0.953 mg/g, respectively. The concentrations of other isoflavones (mainly genistein and daidzein and their derivatives) in soy yogurt remained largely unchanged after the processes compared with the control soy yogurt. Germination of black soybean under fungal stress for 3 days was sufficient to reduce stachyose and raffinose (which cause flatulence) by 92 and 80%, respectively. With a pH value of 4.42, a lactic acid content of 0.262%, and a maximum viable cell count of 2.1 x 10 (8) CFU/mL in the final soy yogurt, soy milk from germinated soybeans under fungal stress was concluded to be a suitable medium for yogurt-making. The resulting soy yogurt had significantly altered micronutrient profiles with significantly reduced oligosaccharides and enriched glyceollins.

  9. Analysis on blast fungus-responsive characters of a flavonoid phytoalexin sakuranetin; accumulation in infected rice leaves, antifungal activity and detoxification by fungus.

    Science.gov (United States)

    Hasegawa, Morifumi; Mitsuhara, Ichiro; Seo, Shigemi; Okada, Kazunori; Yamane, Hisakazu; Iwai, Takayoshi; Ohashi, Yuko

    2014-08-04

    To understand the role of the rice flavonoid phytoalexin (PA) sakuranetin for blast resistance, the fungus-responsive characteristics were studied. Young rice leaves in a resistant line exhibited hypersensitive reaction (HR) within 3 days post inoculation (dpi) of a spore suspension, and an increase in sakuranetin was detected at 3 dpi, increasing to 4-fold at 4 dpi. In the susceptible line, increased sakuranetin was detected at 4 dpi, but not at 3 dpi, by which a large fungus mass has accumulated without HR. Induced expression of a PA biosynthesis gene OsNOMT for naringenin 7-O-methyltransferase was found before accumulation of sakuranetin in both cultivars. The antifungal activity of sakuranetin was considerably higher than that of the major rice diterpenoid PA momilactone A in vitro and in vivo under similar experimental conditions. The decrease and detoxification of sakuranetin were detected in both solid and liquid mycelium cultures, and they took place slower than those of momilactone A. Estimated local concentration of sakuranetin at HR lesions was thought to be effective for fungus restriction, while that at enlarged lesions in susceptible rice was insufficient. These results indicate possible involvement of sakuranetin in blast resistance and its specific relation to blast fungus.

  10. Induction of stilbene phytoalexins in grapevine (Vitis vinifera) and transgenic stilbene synthase-apple plants (Malus domestica) by a culture filtrate of Aureobasidium pullulans.

    Science.gov (United States)

    Rühmann, Susanne; Pfeiffer, Judith; Brunner, Philipp; Szankowski, Iris; Fischer, Thilo C; Forkmann, Gert; Treutter, Dieter

    2013-11-01

    Products containing the epiphytic yeast Aureobasidium pullulans are commercially available and applied by fruit growers to prevent several fungal and bacterial diseases of fruit trees. The proposed beneficial mechanisms relate to limitations of space and nutrients for the pathogens in presence of the rapidly proliferating yeast cells. These explanations ignore the potential of yeasts to elicit the plant's defense. Our experiments aim at clarifying if an autoclaved and centrifuged suspension of A. pullulans may induce defense mechanisms. As a model system, the biosynthesis and accumulation of stilbene phytoalexins in callus and shoots of grapevine Vitis vinifera grown in vitro was used. Yeast application to the plant tissue stimulated stilbene biosynthesis, sometimes at the cost of flavonoids. The expression of the gene encoding stilbene synthase was enhanced and the enzyme showed higher activity while chalcone synthase activity and expression was reduced in some cases. An accumulation of stilbenes was also found in transgenic apple trees (Malus domestica cv. Holsteiner Cox) harboring the stilbene synthase-gene under control of its own promoter. These results clearly show that the application of A. pullulans may induce defense mechanisms of the treated plants.

  11. Effect of Methyl Jasmonate on Phytoalexins Biosynthesis and Induced Disease Resistance to Fusarium oxysporum f. sp. Vasinfectum in Cotton (Gossypium hirsutum L.

    Directory of Open Access Journals (Sweden)

    Yao Kouakou François Konan

    2014-01-01

    Full Text Available The effect of methyl jasmonate (MeJA sprayed on cotton healthy leaves was evaluated in terms of inherent bioactive chemicals induction. The total phenolic content significantly increased after MeJA 5.0 mM treatments compared to the other tested concentrations (0; 2.5; 10; 15; 20 mM. Among the eleven phenolic compounds which were found except for ferulic acid, gossypetin, gossypol, 3-p-coumaroylquinic acid, and piceatannol were identified as major phenolic constituents of cotton. Their content also significantly increased after the MeJA treatment. In addition, gossypol increased 64 times compared to the control, in the 5.0 mM MeJA treatment. Furthermore, cichoric acid, chlorogenic acid, and pterostilbene are synthesized de novo in leaves of MeJA-treated plant. Treatment of cotton leaves with MeJA 5.0 mM followed 72 h of incubation hampered the expression of Fusarium wilt caused by Fusarium oxysporium f. sp. vasinfectum (FOV. MeJA efficiency was concentration and incubation time dependent. Disease severity on MeJA-treated leaves was significantly lower as compared to the control. Therefore, the high content of gossypetin, gossypol, 3-p-coumaroylquinic acid, ferulic acid, and piceatannol and the presence of cichoric acid, chlorogenic acid, and pterostilbene in plants treated with MeJA, contrary to the control, are essential to equip the cotton compounds with defences or phytoalexins against FOV.

  12. Different roles of Enhanced Disease Susceptibility1 (EDS1) bound to and dissociated from Phytoalexin Deficient4 (PAD4) in Arabidopsis immunity.

    Science.gov (United States)

    Rietz, Steffen; Stamm, Anika; Malonek, Stefan; Wagner, Stephan; Becker, Dieter; Medina-Escobar, Nieves; Vlot, A Corina; Feys, Bart J; Niefind, Karsten; Parker, Jane E

    2011-07-01

    • Enhanced Disease Susceptibility1 (EDS1) is an important regulator of plant basal and receptor-triggered immunity. Arabidopsis EDS1 interacts with two related proteins, Phytoalexin Deficient4 (PAD4) and Senescence Associated Gene101 (SAG101), whose combined activities are essential for defense signaling. The different sizes and intracellular distributions of EDS1-PAD4 and EDS1-SAG101 complexes in Arabidopsis leaf tissues suggest that they perform nonredundant functions. • The nature and biological relevance of EDS1 interactions with PAD4 and SAG101 were explored using yeast three-hybrid assays, in vitro analysis of recombinant proteins purified from Escherichia coli, and characterization of Arabidopsis transgenic plants expressing an eds1 mutant (eds1(L262P) ) protein which no longer binds PAD4 but retains interaction with SAG101. • EDS1 forms molecularly distinct complexes with PAD4 or SAG101 without additional plant factors. Loss of interaction with EDS1 reduces PAD4 post-transcriptional accumulation, consistent with the EDS1 physical association stabilizing PAD4. The dissociated forms of EDS1 and PAD4 are fully competent in signaling receptor-triggered localized cell death at infection foci. By contrast, an EDS1-PAD4 complex is necessary for basal resistance involving transcriptional up-regulation of PAD4 itself and mobilization of salicylic acid defenses. • Different EDS1 and PAD4 molecular configurations have distinct and separable functions in the plant innate immune response.

  13. The biosynthesis of phytoalexins in Dianthus caryophyllus L. cell cultures: induction of benzoyl-CoA:anthranilate N-benzoyltransferase activity.

    Science.gov (United States)

    Reinhard, K; Matern, U

    1989-11-15

    It has been shown that cell cultures of Dianthus caryophyllus L. c.v. Eleganz accumulate N-benzoyl-4-methoxyanthranilic acid, previously identified as the phytoalexin methoxydianthramide B, in response to treatment either with a crude elicitor isolated from the cell walls of Phytophthora megasperma f.sp. glycinea or with a commercial yeast extract. Cell-free extracts from the induced cells efficiently catalyzed the N-benzoylation of anthranilate in the presence of benzoyl-CoA. The partially purified transferase was shown to be specific for anthranilate with almost no activity toward 4-hydroxyanthranilate, whereas acyl donors other than benzoyl-CoA such as salicyloyl-, cinnamoyl-, or 4-coumaroyl-CoA were also accepted. Elicitor treatment of the cells additionally induced an S-adenosyl-L-methionine:N-benzoyl-4-hydroxyanthranilate 4-O-methyltransferase activity. We propose, therefore, that methoxydianthramide B is derived from N-benzoylanthranilic acid via N-benzoyl-4-hydroxyanthranilic acid. Dark-grown cells contained little N-benzoyltransferase activity (approx 8 mu kat/kg), which increased roughly ninefold within 6 h following the addition of the elicitor. In addition, phenylalanine ammonia-lyase activity of the cells increased about twofold under these conditions to a maximum (approx 40 mu kat/kg) at 5 h. The rapid induction of both enzyme activities suggests that the shikimate pathway is of crucial importance in the disease resistance response of carnation cells.

  14. LC-ESI-MS/MS method for bioanalytical determination of osteogenic phytoalexin, medicarpin, and its application to preliminary pharmacokinetic studies in rats.

    Science.gov (United States)

    Taneja, Isha; Raju, Kanumuri Siva Rama; Challagundla, Muralikrishna; Raghuvanshi, Ashutosh; Goel, Atul; Wahajuddin, Muhammad

    2015-09-15

    Medicarpin is the active phytoalexin found in the stem bark of Butea monosperma having potent osteogenic activity. An LC-ESI-MS/MS was developed and validated for quantification of medicarpin in rat plasma using liquid-liquid extraction technique and diethyl ether as the extraction solvent. Medicarpin was separated on RP18 column (4.6mm×50mm, 5.0μm) using methanol and 10mM ammonium acetate (pH 4.0) in the ratio of 80:20 (v/v) as mobile phase. The method was linear within the concentration range of 1-500ng/mL and its sensitivity was 1ng/mL. The precision value for intra- and inter-day assays and stability assays was within 0.88-14.22% while the accuracy ranged between 87.46-116.0% at all four QC levels. The validated method was successfully applied to study the preclinical pharmacokinetics of medicarpin in rats. Medicarpin showed multiple peak phenomenon upon oral administration. Its oral bioavailability was 17.43%. It was found to be a rapidly absorbed (Tmax=15min), 81.61% protein bound and pH stable compound. The present study provides important information regarding preliminary pharmacokinetics of medicarpin for its further exploration as a potential therapeutic agent.

  15. Photoelectric converters with quantum coherence

    Science.gov (United States)

    Su, Shan-He; Sun, Chang-Pu; Li, Sheng-Wen; Chen, Jin-Can

    2016-05-01

    Photon impingement is capable of liberating electrons in electronic devices and driving the electron flux from the lower chemical potential to higher chemical potential. Previous studies hinted that the thermodynamic efficiency of a nanosized photoelectric converter at maximum power is bounded by the Curzon-Ahlborn efficiency ηCA. In this study, we apply quantum effects to design a photoelectric converter based on a three-level quantum dot (QD) interacting with fermionic baths and photons. We show that, by adopting a pair of suitable degenerate states, quantum coherences induced by the couplings of QDs to sunlight and fermion baths can coexist steadily in nanoelectronic systems. Our analysis indicates that the efficiency at maximum power is no longer limited to ηCA through manipulation of carefully controlled quantum coherences.

  16. Photoelectric converter; Koden henkan soshi

    Energy Technology Data Exchange (ETDEWEB)

    Sawayama, I.

    1995-04-07

    The conventional solar cell module wherein plural photovoltaic elements formed on a metal substrate are connected and coated by weatherproof and translucent resin has defects such as pinholes, and separation because moisture infiltrating from the outside causes dissolution of such conductive matrix as silver in the collecting electrode. This invention relates to a photoelectric converter which has little decrease in the output under the environment of light irradiation, wherein a photoelectric converting semiconductor, a transparent conductive layer on the above-mentioned semiconductor, and conductive member containing water repellent fine powder grains on this transparent conductive layer are laminated successively. Polytetrafluoroethylene, polydimethyl siloxane, polyethylene, and nylon are desirable to be employed as the water repellent fine powder grains. The fine powder grains are mixed with conductive filler and binder to produce conductive paste, pattern-applied by a screen printing machine, and subjected to thermal treatment to form a conductive member. 3 figs., 1 tab.

  17. Photoelectric converters with quantum coherence.

    Science.gov (United States)

    Su, Shan-He; Sun, Chang-Pu; Li, Sheng-Wen; Chen, Jin-Can

    2016-05-01

    Photon impingement is capable of liberating electrons in electronic devices and driving the electron flux from the lower chemical potential to higher chemical potential. Previous studies hinted that the thermodynamic efficiency of a nanosized photoelectric converter at maximum power is bounded by the Curzon-Ahlborn efficiency η_{CA}. In this study, we apply quantum effects to design a photoelectric converter based on a three-level quantum dot (QD) interacting with fermionic baths and photons. We show that, by adopting a pair of suitable degenerate states, quantum coherences induced by the couplings of QDs to sunlight and fermion baths can coexist steadily in nanoelectronic systems. Our analysis indicates that the efficiency at maximum power is no longer limited to η_{CA} through manipulation of carefully controlled quantum coherences.

  18. Simplified dc to dc converter

    Science.gov (United States)

    Gruber, R. P. (Inventor)

    1984-01-01

    A dc to dc converter which can start with a shorted output and which regulates output voltage and current is described. Voltage controlled switches directed current through the primary of a transformer the secondary of which includes virtual reactance. The switching frequency of the switches is appropriately varied to increase the voltage drop across the virtual reactance in the secondary winding to which there is connected a low impedance load. A starting circuit suitable for voltage switching devices is provided.

  19. Biomass compounds converted to gasoline

    Energy Technology Data Exchange (ETDEWEB)

    1979-10-08

    It is claimed that corn, castor, and jojoba oils as well as Hevea latex can be converted in high yields to gasoline by passage over zeolite catalysts at 450 degrees to 500 degrees centigrade. Gasoline yields are 60% from corn oil (essentially tristearin), compared with 50% yields from methanol. Latex depolymerizes before conversion. Fat and oil molecules adopt conformations that enable them to enter zeolite interstices, resulting in high yields of C6 to C9 aromatics.

  20. Workshop 4 Converter cooling & recuperation

    Science.gov (United States)

    Iles, Peter; Hindman, Don

    1995-01-01

    Cooling the PV converter increases the overall TPV system efficiency, and more than offsets the losses incurred in providing cooling systems. Convective air flow methods may be sufficient, and several standard water cooling systems, including thermo-syphon radiators, capillary pumps or microchannel plates, are available. Recuperation is used to increase system efficiency, rather than to increase the emitter temperature. Recuperators operating at comparable high temperatures, such as in high temperature turbines have worked effectively.

  1. Computerized simulation of converter process

    Energy Technology Data Exchange (ETDEWEB)

    Jalkanen, H.; Suomi, M.L.; Wallgren, M. [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Metallurgy

    1996-12-31

    Converter process is essentially an oxidising refining process aiming in addition to (1) the primary refining action, decarburisation of high carbon iron melt, also to (2) maximal elimination of impurity elements, especially silicon, phosphorus and sulphur, (3) melting of substantial amounts of scrap using the extra heat released in oxidation reactions and (4) to exact final steel temperature control, optimal for further treatments. `Quantitative modelling of such a complex non-stationary chemical process as oxygen converting necessitates extensive formulation of chemical and thermal evolution of the process in connection with the technological properties of the reactor and the process control measures. A comprehensive converter simulation program like CONSIM-3. 1 and its preceding versions that is based on the theoretical and practical knowledge on the process can be used for (1) educating specialists and smelter personnel, (2) planning of the blowing programs, (3) developing and testing of process control systems and after some elaboration and restructuring (4) it can be integrated to static or dynamic process control systems. (orig.) SULA 2 Research Programme; 10 refs.

  2. Design and Control for the Buck-Boost Converter Combining 1-Plus-D Converter and Synchronous Rectified Buck Converters

    Directory of Open Access Journals (Sweden)

    Jeevan Naik

    2015-06-01

    Full Text Available In this paper, a design and control for the buck-boost converter, i.e., 1-plus-D converter with a positive output voltage, is presented, which combines the 1-plus-D converter and the synchronous rectified (SR buck converter. By doing so, the problem in voltage bucking of the 1-plus-D converter can be solved, thereby increasing the application capability of the 1-plus-D converter. Since such a converter operates in continuous conduction mode inherently, it possesses the nonpulsating output current, thereby not only decreasing the current stress on the output capacitor but also reducing the output voltage ripple. Above all, both the 1-plus-D converter and the SR buck converter, combined into a buck–boost converter with no right-half plane zero, use the same power switches, thereby causing the required circuit to be compact and the corresponding cost to be down. Furthermore, during the magnetization period, the input voltage of the 1-plus-D converter comes from the input voltage source, whereas during the demagnetization period, the input voltage of the 1-plus-D converter comes from the output voltage of the SR buck converter.

  3. Simulation Results of Double Forward Converter

    Directory of Open Access Journals (Sweden)

    P. Vijaya KUMAR

    2009-12-01

    Full Text Available This work aims to find a better forward converter for DC to DC conversion.Simulation of double forward converter in SMPS system is discussed in this paper. Aforward converter with RCD snubber to synchronous rectifier and/or to current doubleris also discussed. The evolution of the forward converter is first reviewed in a tutorialfashion. Performance parameters are discussed including operating principle, voltageconversion ratio, efficiency, device stress, small-signal dynamics, noise and EMI. Itscircuit operation and its performance characteristics of the forward converter with RCDsnubber and double forward converter are described and the simulation results arepresented.

  4. Si Bule Masuk Islam: Western Converts to Islam in Indonesia - more than just Converts of Convenience?

    OpenAIRE

    M. A. Kevin Brice

    2015-01-01

    In discussing converts to Islam, two different types of converts are often identified based on the reason for conversion: converts of convenience and converts of conviction. The common view is that in most (if not all) cases, conversion to Islam in Indonesia by Westerners is about facilitating marriage and so the converts should be classified as converts of convenience. Evidence of the commonality of this view is considered by reference to advice offered to Westerners about marriage to Indone...

  5. multilevel buck converter for automotive electrical load

    African Journals Online (AJOL)

    user

    development of DCM based buck converter and its applications in the HEVs/EVs using ... The paper also highlights the implications of implementing a single stage buck converter, and ..... instance when the saw tooth signal within the internal.

  6. Converting pest insects into food

    DEFF Research Database (Denmark)

    Offenberg, Hans Joachim; Wiwatwittaya, Decha

    2010-01-01

    on management, 32-115 kg ant brood (mainly new queens) was harvested per ha per year without detrimental effect on colony survival and worker ant densities. This suggest that ant biocontrol and ant harvest can be sustainable integrated in plantations and double benefits derived. As ant production is fuelled...... by pest insects, problematic pests are converted into food and additional earnings. To assess the profitability of providing additional food for the ants, O. smaragdina food conversion efficiency (ECI) was estimated in the laboratory. This estimate suggests the feeding of weaver ants in ant farms...

  7. Power electronics converters and regulators

    CERN Document Server

    Dokić, Branko L

    2015-01-01

    This book is the result of the extensive experience the authors gained through their year-long occupation at the Faculty of Electrical Engineering at the University of Banja Luka. Starting at the fundamental basics of electrical engineering, the book guides the reader into this field and covers all the relevant types of converters and regulators. Understanding is enhanced by the given examples, exercises and solutions. Thus this book can be used as a textbook for students, for self-study or as a reference book for professionals.

  8. Converting pest insects into food

    DEFF Research Database (Denmark)

    Offenberg, Hans Joachim; Wiwatwittaya, Decha

    2010-01-01

    Canopy dwelling weaver ants (Oecophylla spp.) are used to control a variety of pests in a number of tropical tree crops. What is less familiar is the existence of commercial markets where these ants and their brood are sold for (i) human consumption, (ii) pet food or (iii) traditional medicine...... by pest insects, problematic pests are converted into food and additional earnings. To assess the profitability of providing additional food for the ants, O. smaragdina food conversion efficiency (ECI) was estimated in the laboratory. This estimate suggests the feeding of weaver ants in ant farms...

  9. OAM mode converter in twisted fibers

    DEFF Research Database (Denmark)

    Usuga Castaneda, Mario A.; Beltran-Mejia, Felipe; Cordeiro, Cristiano

    2014-01-01

    We analyze the case of an OAM mode converter based on a twisted fiber, through finite element simulations where we exploit an equivalence between geometric and material transformations. The obtained converter has potential applications in MDM. © 2014 OSA.......We analyze the case of an OAM mode converter based on a twisted fiber, through finite element simulations where we exploit an equivalence between geometric and material transformations. The obtained converter has potential applications in MDM. © 2014 OSA....

  10. Analysis and design of converters in Matlab

    OpenAIRE

    Lorente Sanjurjo, Rodrigo

    2010-01-01

    This project will try to provide better understanding of data converters, more specifically in the mathematical representation and coding of non idealities of the converter. As programming tool it will be used the MATLAB environment, with which will carry out the coding and the analysis of the behavior of the converters by adding diverse nonlinearities, taking advantage of the simplicity, clarity, and extensibility that provides this environment. Summarizing, it is going to study the converte...

  11. Ecologically Optimal Solution of Power Semiconductors Converters

    Directory of Open Access Journals (Sweden)

    Ivan Lokseninec

    2003-01-01

    Full Text Available One of the relevant scientific programs of Department of Power Electrical Systems is research of ecologically optimal topologies main circuits of power converters. This paper presents some methods how to reduce unfavourable influences of power converters on the grid. The achieved results were applieed in praxis, especially in the power converters produced by Electrotechnical Research and Projecting Institute in Nova Dubnica.

  12. Lesion simulating disease1, enhanced disease susceptibility1, and phytoalexin deficient4 conditionally regulate cellular signaling homeostasis, photosynthesis, water use efficiency, and seed yield in Arabidopsis.

    Science.gov (United States)

    Wituszynska, Weronika; Slesak, Ireneusz; Vanderauwera, Sandy; Szechynska-Hebda, Magdalena; Kornas, Andrzej; Van Der Kelen, Katrien; Mühlenbock, Per; Karpinska, Barbara; Mackowski, Sebastian; Van Breusegem, Frank; Karpinski, Stanislaw

    2013-04-01

    There is growing evidence that for a comprehensive insight into the function of plant genes, it is crucial to assess their functionalities under a wide range of conditions. In this study, we examined the role of lesion simulating disease1 (LSD1), enhanced disease susceptibility1 (EDS1), and phytoalexin deficient4 (PAD4) in the regulation of photosynthesis, water use efficiency, reactive oxygen species/hormonal homeostasis, and seed yield in Arabidopsis (Arabidopsis thaliana) grown in the laboratory and in the field. We demonstrate that the LSD1 null mutant (lsd1), which is known to exhibit a runaway cell death in nonpermissive conditions, proves to be more tolerant to combined drought and high-light stress than the wild type. Moreover, depending on growing conditions, it shows variations in water use efficiency, salicylic acid and hydrogen peroxide concentrations, photosystem II maximum efficiency, and transcription profiles. However, despite these changes, lsd1 demonstrates similar seed yield under all tested conditions. All of these traits depend on EDS1 and PAD4. The differences in the pathways prevailing in the lsd1 in various growing environments are manifested by the significantly smaller number of transcripts deregulated in the field compared with the laboratory, with only 43 commonly regulated genes. Our data indicate that LSD1, EDS1, and PAD4 participate in the regulation of various molecular and physiological processes that influence Arabidopsis fitness. On the basis of these results, we emphasize that the function of such important regulators as LSD1, EDS1, and PAD4 should be studied not only under stable laboratory conditions, but also in the environment abounding in multiple stresses.

  13. Cinnamate:CoA Ligase Initiates the Biosynthesis of a Benzoate-Derived Xanthone Phytoalexin in Hypericum calycinum Cell Cultures1[W][OA

    Science.gov (United States)

    Gaid, Mariam M.; Sircar, Debabrata; Müller, Andreas; Beuerle, Till; Liu, Benye; Ernst, Ludger; Hänsch, Robert; Beerhues, Ludger

    2012-01-01

    Although a number of plant natural products are derived from benzoic acid, the biosynthesis of this structurally simple precursor is poorly understood. Hypericum calycinum cell cultures accumulate a benzoic acid-derived xanthone phytoalexin, hyperxanthone E, in response to elicitor treatment. Using a subtracted complementary DNA (cDNA) library and sequence information about conserved coenzyme A (CoA) ligase motifs, a cDNA encoding cinnamate:CoA ligase (CNL) was isolated. This enzyme channels metabolic flux from the general phenylpropanoid pathway into benzenoid metabolism. HcCNL preferred cinnamic acid as a substrate but failed to activate benzoic acid. Enzyme activity was strictly dependent on the presence of Mg2+ and K+ at optimum concentrations of 2.5 and 100 mm, respectively. Coordinated increases in the Phe ammonia-lyase and HcCNL transcript levels preceded the accumulation of hyperxanthone E in cell cultures of H. calycinum after the addition of the elicitor. HcCNL contained a carboxyl-terminal type 1 peroxisomal targeting signal made up by the tripeptide Ser-Arg-Leu, which directed an amino-terminal reporter fusion to the peroxisomes. Masking the targeting signal by carboxyl-terminal reporter fusion led to cytoplasmic localization. A phylogenetic tree consisted of two evolutionarily distinct clusters. One cluster was formed by CoA ligases related to benzenoid metabolism, including HcCNL. The other cluster comprised 4-coumarate:CoA ligases from spermatophytes, ferns, and mosses, indicating divergence of the two clades prior to the divergence of the higher plant lineages. PMID:22992510

  14. A γ-lactamase from cereal infecting Fusarium spp. catalyses the first step in the degradation of the benzoxazolinone class of phytoalexins.

    Science.gov (United States)

    Kettle, Andrew J; Carere, Jason; Batley, Jacqueline; Benfield, Aurelie H; Manners, John M; Kazan, Kemal; Gardiner, Donald M

    2015-10-01

    The benzoxazolinone class of phytoalexins are released by wheat, maize, rye and other agriculturally important species in the Poaceae family upon pathogen attack. Benzoxazolinones show antimicrobial effects on plant pathogens, but certain fungi have evolved mechanisms to actively detoxify these compounds which may contribute to the virulence of the pathogens. In many Fusarium spp. a cluster of genes is thought to be involved in the detoxification of benzoxazolinones. However, only one enzyme encoded in the cluster has been unequivocally assigned a role in this process. The first step in the detoxification of benzoxazolinones in Fusarium spp. involves the hydrolysis of a cyclic ester bond. This reaction is encoded by the FDB1 locus in F. verticillioides but the underlying gene is yet to be cloned. We previously proposed that FDB1 encodes a γ-lactamase, and here direct evidence for this is presented. Expression analyses in the important wheat pathogen F. pseudograminearum demonstrated that amongst the three predicted γ-lactamase genes only the one designated as FDB1, part of the proposed benzoxazolinone cluster in F. pseudograminearum, was strongly responsive to exogenous benzoxazolinone application. Analysis of independent F. pseudograminearum and F. graminearum FDB1 gene deletion mutants, as well as biochemical assays, demonstrated that the γ-lactamase enzyme, encoded by FDB1, catalyses the first step in detoxification of benzoxazolinones. Overall, our results support the notion that Fusarium pathogens that cause crown rot and head blight on wheat have adopted strategies to overcome host-derived chemical defences. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. A dc to dc converter

    Science.gov (United States)

    Willis, A. E.; Gould, J. M.; Matheney, J. L.; Garrett, H. (Inventor)

    1984-01-01

    The object of the invention is to provide an improved converter for converting one direct current voltage to another. A plurality of phased square wave voltages are provided from a ring counter through amplifiers to a like plurality of output transformers. Each of these transformers has two windings, and S(1) winding and an S(2) winding. The S(1) windings are connected in series, then the S(2) windings are connected in series, and finally, the two sets of windings are connected in series. One of six SCRs is connected between each two series connected windings to a positive output terminal and one of diodes is connected between each set of two windings of a zero output terminal. By virtue of this configuration, a quite high average direct current voltage is obtained, which varies between full voltage and two-thirds full voltage rather than from full voltage to zero. Further, its variation, ripple frequency, is reduced to one-sixth of that present in a single phase system. Application to raising battery voltage for an ion propulsion system is mentioned.

  16. Valuing Convertible Bonds Based on LSRQM Method

    Directory of Open Access Journals (Sweden)

    Jian Liu

    2014-01-01

    Full Text Available Convertible bonds are one of the essential financial products for corporate finance, while the pricing theory is the key problem to the theoretical research of convertible bonds. This paper demonstrates how to price convertible bonds with call and put provisions using Least-Squares Randomized Quasi-Monte Carlo (LSRQM method. We consider the financial market with stochastic interest rates and credit risk and present a detailed description on calculating steps of convertible bonds value. The empirical results show that the model fits well the market prices of convertible bonds in China’s market and the LSRQM method is effective.

  17. Efficiency of Capacitively Loaded Converters

    DEFF Research Database (Denmark)

    Andersen, Thomas; Huang, Lina; Andersen, Michael A. E.;

    2012-01-01

    This paper explores the characteristic of capacitance versus voltage for dielectric electro active polymer (DEAP) actuator, 2kV polypropylene film capacitor as well as 3kV X7R multi layer ceramic capacitor (MLCC) at the beginning. An energy efficiency for capacitively loaded converters...... is introduced as a definition of efficiency. The calculated and measured efficiency curves for charging DEAP actuator, polypropylene film capacitor and X7R MLCC are provided and compared. The attention has to be paid for the voltage dependent capacitive load, like X7R MLCC, when evaluating the charging...... polypropylene film capacitor can be the equivalent capacitive load. Because of the voltage dependent characteristic, X7R MLCC cannot be used to replace the DEAP actuator. However, this type of capacitor can be used to substitute the capacitive actuator with voltage dependent property at the development phase....

  18. Reliability of Wave Energy Converters

    DEFF Research Database (Denmark)

    Ambühl, Simon

    . Structural reliability considerations and optimizations impact operation and maintenance (O&M) costs as well as the initial investment costs. Furthermore, there is a control system for WEC applications which defines the harvested energy but also the loads onto the structure. Therefore, extreme loads but also...... WEPTOS. Calibration of safety factors are performed for welded structures at theWavestar device including different control systems for harvesting energy from waves. In addition, a case study of different O&M strategies for WECs is discussed, and an example of reliability-based structural optimization......There are many different working principles for wave energy converters (WECs) which are used to produce electricity from waves. In order for WECs to become successful and more competitive to other renewable electricity sources, the consideration of the structural reliability of WECs is essential...

  19. Reliability of Wave Energy Converters

    DEFF Research Database (Denmark)

    Ambühl, Simon

    for welded structures at the Wavestar device includingdifferent control systems for harvesting energy from waves. In addition, a casestudy of different O&M strategies for WECs is discussed, and an example ofreliability-based structural optimization of the Wavestar foundation ispresented. The work performed......There are many different working principles for wave energy converters (WECs) which are used to produce electricity from waves. In order for WECs tobecome successful and more competitive to other renewable electricity sources,the consideration of the structural reliability of WECs is essential.......Structural reliability considerations and optimizations impact operation andmaintenance (O&M) costs as well as the initial investment costs.Furthermore, there is a control system for WEC applications which defines theharvested energy but also the loads onto the structure. Therefore, extremeloads but also fatigue loads...

  20. Reliability of Wave Energy Converters

    DEFF Research Database (Denmark)

    Ambühl, Simon

    There are many different working principles for wave energy converters (WECs) which are used to produce electricity from waves. In order for WECs to become successful and more competitive to other renewable electricity sources, the consideration of the structural reliability of WECs is essential....... Structural reliability considerations and optimizations impact operation and maintenance (O&M) costs as well as the initial investment costs. Furthermore, there is a control system for WEC applications which defines the harvested energy but also the loads onto the structure. Therefore, extreme loads but also...... of the Wavestar foundation is presented. The work performed in this thesis focuses on the Wavestar and WEPTOS WEC devices which are only two working principles out of a large diversity. Therefore, in order to gain general statements and give advice for standards for structural WEC designs, more working principles...

  1. Manufacturing method of photoelectric converter

    Energy Technology Data Exchange (ETDEWEB)

    Toda, Koji; Niwa, Yasuo

    1987-06-24

    In a method of making a thin film for a photoelectric converter by a method to form an electroconductive layer by burning a mixture of lead oxide and chromic oxide, thickness of the film was limited and the poreless uniform film was not obtainable. The intransparency of the film gave low conversion efficiency only. This invention enabled to obtain a transparent film wherein an oxide (containing lead and chrome) is used as a target to form, in vacuum, a thin film of the oxide, and then this thin film is heat-treated in an atmosphere at least containing lead. Thin transparent film was obtained enhancing the conversion efficiency. High quality and high reliability are ensured because a poreless uniform film can be obtained. Cost was reduced because mass-production was made possible by the use of a vacuum technique. (5 figs)

  2. The SSG Wave Energy Converter

    DEFF Research Database (Denmark)

    Vicinanza, Diego; Margheritini, Lucia; Kofoed, Jens Peter

    2012-01-01

    The Sea-wave Slot-cone Generator concept (SSG) is a Wave Energy Converter based on the wave overtopping principle utilizing several reservoirs placed on top of each other, in which the energy of the incoming wave will be stored as potential energy. The water captured in the reservoirs will then run...... through turbines for electricity production. The system utilizes a wide spectrum of different wave conditions by means of multiple reservoirs, located at different levels above the still water level. Thereby, it obtains a high overall efficiency and it can be suitable for shoreline and breakwater...... applications, presenting particular advantages such as: sharing structure costs, availability of grid connection and infrastructures, recirculation of water inside the harbor, as the outlet of the turbines is on the rear part of the system. Recently, plans for the SSG pilot installation were in progress...

  3. Stimulation of de novo synthesis of L-phenylalanine ammonia-lyase in relation to phytoalexin accumulation in Colletotrichum lindemuthianum elicitor-treated cell suspension cultures of french bean (Phaseolus vulgaris).

    Science.gov (United States)

    Dixon, R A; Lamb, C J

    1979-09-03

    (1) The regulation of the accumulation of the isoflavonoid-derived phytoalexin phaseollin in cell suspension cultures of Dwarf French Bean (Phaseolus vulgaris/ has been investigated. (2) An elicitor preparation from cell walls of Colletotrichum lindemuthianum, the causal agent of anthracnose disease of French bean, caused a marked accumulation of phaseollin in the cultures. The elicitor induced phaseollin accumulation to a level of 60% that obtained with the artificial elicitor autoclaved ribonuclease A and was maximally active at a concentration (weight basis) of at least 50 times lower than required for maximal response to ribonuclease. (3) Elicitor preparations from cell walls of Phytophthora megasperma var. sojae, a fungal pathogen of soybean, and Botrytis cinerea, the common grey mould, were much less effective than the C. lindemuthianum wall-released elicitor. (4) There was a marked but transient increase in the extractable activity of phenylalanine ammonia-lyase, the enzyme catalysing the first reaction in the biosynthesis of phaseollin from L-phenylalanine, in response to the elicitor from C. lindemuthianum. (5) Comparative density labelling with 2H from 2H2O indicated that the elicitor stimulates de novo synthesis of phenylalanine ammonie findings provide the basis of a scheme for elicitor induction of phytoalexin accumulation.

  4. Three-phase AC-AC power converters based on matrix converter topology matrix-reactance frequency converters concept

    CERN Document Server

    Szczesniak, Pawel

    2013-01-01

    AC voltage frequency changes is one of the most important functions of solid state power converters. The most desirable features in frequency converters are the ability to generate load voltages with arbitrary amplitude and frequency, sinusoidal currents and voltages waveforms; the possibility of providing unity power factor for any load; and, finally, a simple and compact power circuit. Over the past decades, a number of different frequency converter topologies have appeared in the literature, but only the converters with either a voltage or current DC link are commonly used in industrial app

  5. Radiation-Tolerant DC-DC Converters

    Science.gov (United States)

    Skutt, Glenn; Sable, Dan; Leslie, Leonard; Graham, Shawn

    2012-01-01

    A document discusses power converters suitable for space use that meet the DSCC MIL-PRF-38534 Appendix G radiation hardness level P classification. A method for qualifying commercially produced electronic parts for DC-DC converters per the Defense Supply Center Columbus (DSCC) radiation hardened assurance requirements was developed. Development and compliance testing of standard hybrid converters suitable for space use were completed for missions with total dose radiation requirements of up to 30 kRad. This innovation provides the same overall performance as standard hybrid converters, but includes assurance of radiation- tolerant design through components and design compliance testing. This availability of design-certified radiation-tolerant converters can significantly reduce total cost and delivery time for power converters for space applications that fit the appropriate DSCC classification (30 kRad).

  6. Converting Relational Database Into Xml Document

    Directory of Open Access Journals (Sweden)

    Kanagaraj.S

    2012-03-01

    Full Text Available XML (Extensible Markup Language is emerging and gradually accepted as the standard for data interchange in the Internet world. Interoperation of relational database and XML database involves schema and data translations. Through EER (extended entity relationship model can convert the schema of relational database into XML. The semantics of the relational database, captured in EER diagram, are mapped to XML schema using stepwise procedures and mapped to XML document under the definitions of the XML schema. Converting Relational Database into XML Document is a process of converting the existing databases into XML file format. Existing conversion techniques convert a single database into xml. The proposed approach performs the conversion of databases like Ms-Access, MS-SQL to XML file format. Read the tables information from the corresponding database and generate code for the appropriate databases and convert the tables into XML flat file format. This converted XML file is been presented to the user.

  7. Ocean floor mounting of wave energy converters

    Science.gov (United States)

    Siegel, Stefan G

    2015-01-20

    A system for mounting a set of wave energy converters in the ocean includes a pole attached to a floor of an ocean and a slider mounted on the pole in a manner that permits the slider to move vertically along the pole and rotate about the pole. The wave energy converters can then be mounted on the slider to allow adjustment of the depth and orientation of the wave energy converters.

  8. Development of a Modular Power Converter

    Science.gov (United States)

    Stepanov, A.; Biesenieks, L.; Sokolovs, A.; Galkin, I.

    2009-01-01

    This report describes the most important details of elaboration of a versatile power module that can be utilized as a part of various converters. Two or more modules connected together can form a frequency converter or multilevel converter or 3-phase inverter/rectifier etc. Initially the module was developed for fast prototyping of uninterruptible power supplies and energy systems with alternative energy sources. The module can be used also as a basis for laboratory equipment of the power electronics course.

  9. Regeneration of ZVS converter with Resonant inductor

    Directory of Open Access Journals (Sweden)

    J.Sivavara Prasad

    2011-09-01

    Full Text Available This paper presents an analysis of the regeneration of zero-voltage-switching converter with resonant inductor, quasi-resonant converters, and full-bridge zero-voltage-switched PWM Converter. The design of a clamping circuit considering a saturable resonant inductor is presented and compared with the design of a clamping circuit with a linear resonant inductor. A diode model with reverse recovery is employed to simulate the effects.

  10. Fundamentals and hard-switching converters

    CERN Document Server

    Ioinovici, Adrian

    2013-01-01

    Volume 1 Fundamentals and Hard-switching Converters introduces the key challenges in power electronics from basic components to operation principles and presents classical hard- and soft-switching DC to DC converters, rectifiers and inverters. At a more advanced level, it provides comprehensive analysis of DC and AC models comparing the available approaches for their derivation and results. A full treatment of DC to DC hard-switching converters is given, from fundamentals to modern industrial solutions and practical engineering insight. The author elucidates various contradictions and misunderstandings in the literature, for example, in the treatment of the discontinuous conduction operation or in deriving AC small-signal models of converters.

  11. DC/DC Converter Stability Testing Study

    Science.gov (United States)

    Wang, Bright L.

    2008-01-01

    This report presents study results on hybrid DC/DC converter stability testing methods. An input impedance measurement method and a gain/phase margin measurement method were evaluated to be effective to determine front-end oscillation and feedback loop oscillation. In particular, certain channel power levels of converter input noises have been found to have high degree correlation with the gain/phase margins. It becomes a potential new method to evaluate stability levels of all type of DC/DC converters by utilizing the spectral analysis on converter input noises.

  12. Commutation Processes in Multiresonant ZVS Bridge Converter

    Directory of Open Access Journals (Sweden)

    Miroslaw Luft

    2008-01-01

    Full Text Available The analysis of the multiresonant ZVS DC/DC bridge converter is presented. The control system of the converter is basedon the method of frequency control at the constant time of transistor turn-off with a phase shift. The operation of the circuit is givenand the operating range of the converter is defined where ZVS switching operation is assured. Control characteristics are given andthe converter’s efficiency is defined. The circuit’s operation is analysed on the basis of results of the converter simulation tests using Simplorer programme.

  13. Reliability of Power Electronic Converter Systems

    DEFF Research Database (Denmark)

    -link capacitance in power electronic converter systems; wind turbine systems; smart control strategies for improved reliability of power electronics system; lifetime modelling; power module lifetime test and state monitoring; tools for performance and reliability analysis of power electronics systems; fault......-tolerant adjustable speed drive systems; mission profile oriented reliability design in wind turbine and photovoltaic systems; reliability of power conversion systems in photovoltaic applications; power supplies for computers; and high-power converters. Reliability of Power Electronic Converter Systems is essential...... reading for researchers, professionals and students working with power electronics and their applications, particularly those specializing in the development and application of power electronic converters and systems....

  14. Multilevel converters for 10 MW Wind Turbines

    DEFF Research Database (Denmark)

    Ma, Ke; Blaabjerg, Frede

    2011-01-01

    Several promising multi-level converter configurations for 10 MW Wind Turbines both with direct drive and one-stage gear box drive using Permanent Magnet Synchronous Generator (PMSG) are proposed, designed and compared. Reliability is a crucial indicator for large scale wind power converters...

  15. Present trends in HVDC converter station design

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, Lennart; Asplund, Gunnar; Bjorklund, Hans; Flisberg, Gunnar [ABB Power Systems AB, Ludvika (Sweden)

    1994-12-31

    HVDC converter station technology has developed rapidly to satisfy increasing requirements during past 10 - 15 years, but there has not been any dramatic changes since thyristor valves were introduced in the mid 70s. This paper describes some recent and expected future developments, that will substantiality change and simplify future converter stations. (author) 4 refs., 7 figs.

  16. High-Efficiency dc/dc Converter

    Science.gov (United States)

    Sturman, J.

    1982-01-01

    High-efficiency dc/dc converter has been developed that provides commonly used voltages of plus or minus 12 Volts from an unregulated dc source of from 14 to 40 Volts. Unique features of converter are its high efficiency at low power level and ability to provide output either larger or smaller than input voltage.

  17. Power Converters Secure Electronics in Harsh Environments

    Science.gov (United States)

    2013-01-01

    In order to harden power converters for the rigors of space, NASA awarded multiple SBIR contracts to Blacksburg, Virginia-based VPT Inc. The resulting hybrid DC-DC converters have proven valuable in aerospace applications, and as a result the company has generated millions in revenue from the product line and created four high-tech jobs to handle production.

  18. High Precision Current Measurement for Power Converters

    CERN Document Server

    Cerqueira Bastos, M

    2015-01-01

    The accurate measurement of power converter currents is essential to controlling and delivering stable and repeatable currents to magnets in particle accelerators. This paper reviews the most commonly used devices for the measurement of power converter currents and discusses test and calibration methods.

  19. Time-Interleaved Analog to Digital Converters

    NARCIS (Netherlands)

    Louwsma, S.M.; van Tuijl, Adrianus Johannes Maria; Nauta, Bram

    2010-01-01

    This book describes the research carried out by our PhD student Simon Louwsma at the University of Twente, The Netherlands in the field of high-speed Analogto- Digital (AD) converters. AD converters are crucial circuits for modern systems where information is stored or processed in digital form. Due

  20. Input-output rearrangement of isolated converters

    DEFF Research Database (Denmark)

    Madsen, Mickey Pierre; Kovacevic, Milovan; Mønster, Jakob Døllner;

    2015-01-01

    is not a requirement. The proposed technique is particularly valuable in power conversion at very high frequencies, and may be combined with other stress reduction methods. Finally, the new arrangements are experimentally verified both on off the shelf converters and on a VHF resonant SEPIC converter. All results...

  1. Modeling and Simulation of Matrix Converter

    DEFF Research Database (Denmark)

    Liu, Fu-rong; Klumpner, Christian; Blaabjerg, Frede

    2005-01-01

    This paper discusses the modeling and simulation of matrix converter. Two models of matrix converter are presented: one is based on indirect space vector modulation and the other is based on power balance equation. The basis of these two models is• given and the process on modeling is introduced...

  2. Radiation Effects on DC-DC Converters

    Science.gov (United States)

    Zhang, De-Xin; AbdulMazid, M. D.; Attia, John O.; Kankam, Mark D. (Technical Monitor)

    2001-01-01

    In this work, several DC-DC converters were designed and built. The converters are Buck Buck-Boost, Cuk, Flyback, and full-bridge zero-voltage switched. The total ionizing dose radiation and single event effects on the converters were investigated. The experimental results for the TID effects tests show that the voltages of the Buck Buck-Boost, Cuk, and Flyback converters increase as total dose increased when using power MOSFET IRF250 as a switching transistor. The change in output voltage with total dose is highest for the Buck converter and the lowest for Flyback converter. The trend of increase in output voltages with total dose in the present work agrees with those of the literature. The trends of the experimental results also agree with those obtained from PSPICE simulation. For the full-bridge zero-voltage switch converter, it was observed that the dc-dc converter with IRF250 power MOSFET did not show a significant change of output voltage with total dose. In addition, for the dc-dc converter with FSF254R4 radiation-hardened power MOSFET, the output voltage did not change significantly with total dose. The experimental results were confirmed by PSPICE simulation that showed that FB-ZVS converter with IRF250 power MOSFET's was not affected with the increase in total ionizing dose. Single Event Effects (SEE) radiation tests were performed on FB-ZVS converters. It was observed that the FB-ZVS converter with the IRF250 power MOSFET, when the device was irradiated with Krypton ion with ion-energy of 150 MeV and LET of 41.3 MeV-square cm/mg, the output voltage increased with the increase in fluence. However, for Krypton with ion-energy of 600 MeV and LET of 33.65 MeV-square cm/mg, and two out of four transistors of the converter were permanently damaged. The dc-dc converter with FSF254R4 radiation hardened power MOSFET's did not show significant change at the output voltage with fluence while being irradiated by Krypton with ion energy of 1.20 GeV and LET of 25

  3. Modelling, analyses and design of switching converters

    Science.gov (United States)

    Cuk, S. M.; Middlebrook, R. D.

    1978-01-01

    A state-space averaging method for modelling switching dc-to-dc converters for both continuous and discontinuous conduction mode is developed. In each case the starting point is the unified state-space representation, and the end result is a complete linear circuit model, for each conduction mode, which correctly represents all essential features, namely, the input, output, and transfer properties (static dc as well as dynamic ac small-signal). While the method is generally applicable to any switching converter, it is extensively illustrated for the three common power stages (buck, boost, and buck-boost). The results for these converters are then easily tabulated owing to the fixed equivalent circuit topology of their canonical circuit model. The insights that emerge from the general state-space modelling approach lead to the design of new converter topologies through the study of generic properties of the cascade connection of basic buck and boost converters.

  4. Qualitative model of a plasma photoelectric converter

    Science.gov (United States)

    Gorbunov, N. A.; Flamant, G.

    2009-01-01

    A converter of focused optical radiation into electric current is considered on the basis of the photovoltaic effect in plasmas. The converter model is based on analysis of asymmetric spatial distributions of charge particle number density and ambipolar potential in the photoplasma produced by external optical radiation focused in a heat pipe filled with a mixture of alkali vapor and a heavy inert gas. Energy balance in the plasma photoelectric converter is analyzed. The conditions in which the external radiation energy is effectively absorbed in the converter are indicated. The plasma parameters for which the energy of absorbed optical radiation is mainly spent on sustaining the ambipolar field in the plasma are determined. It is shown that the plasma photoelectric converter makes it possible to attain a high conversion efficiency for focused solar radiation.

  5. Transformer Isolated Buck-Boost Converters

    Directory of Open Access Journals (Sweden)

    Barry W. Williams

    2016-12-01

    Full Text Available Of the single-switch dc-to-dc converters, those with the buck-boost voltage transfer function offer most potential for transformer coupling, hence isolation, at the kilowatt level. This paper highlights the limitations of the traditional magnetic coupled, buck-boost topology. Then four split-capacitor transformer-coupled topologies (specifically the Cuk, sepic, zeta, and a new, converters with a common ac equivalent circuit are explored, that do not temporarily store core magnetic energy as does the traditional isolated buck-boost converter nor have a core dc magnetizing current bias, as with the sepic and zeta transformer coupled topologies. Core dc bias capacitive voltage compensation is a practical design constraint in three of the four topologies, while all four must cater for stray and leakage inductance effects. Simulations and experimental results for the new converter at 408W support the transformer-coupled, single-switch dc-to-dc converter concepts investigated.

  6. Periodic Control of Power Electronic Converters

    DEFF Research Database (Denmark)

    Zhou, Keliang; Danwei, Wang; Yang, Yongheng

    Advanced power electronic converters convert, control and condition electricity. Power converters require control strategies for periodic signal compensation to assure good power quality and stable power system operation. This comprehensive text presents the most recent internal model principle...... based periodic control technology, which offers the perfect periodic control solution for power electronic conversion. It also provides complete analysis and synthesis methods for periodic control systems, and plenty of practical examples to demonstrate the validity of proposed periodic control...... technology for power converters. It proposes a unified framework for housing periodic control schemes for power converters, and provides a general proportional-integral-derivative control solution to periodic signal compensation in extensive engineering applications. Periodic Control of Power Electronic...

  7. SPECTRAL ANALYSIS OF BUCK AND SEPIC CONVERTERS

    Directory of Open Access Journals (Sweden)

    CHAKIB ALAOUI

    2011-02-01

    Full Text Available Switched mode power converters generate harmonic currents, which will be injected into the utility grid, causing distortion of the utility waveform. They also become a source for the generation of EMI, which may affect the communication systems. This work is about the design and evaluation of the two most frequently used SMPS used in step down mode of operation: the Buck converter and the Sepic converter working in step-down mode of operation. These converters were designed using optimized equations for their components ratings. Simulation results show that although the Buck output voltage is low in harmonics, it has high harmonic contents in currents circulating in its inductor and diode, and hence requires strong filtering. The Sepic converterhas lower harmonic contents than the Buck converter.

  8. A novel power converter for photovoltaic applications

    Science.gov (United States)

    Yuvarajan, S.; Yu, Dachuan; Xu, Shanguang

    A simple and economical power conditioner to convert the power available from solar panels into 60 Hz ac voltage is described. The raw dc voltage from the solar panels is converted to a regulated dc voltage using a boost converter and a large capacitor and the dc output is then converted to 60 Hz ac using a bridge inverter. The ratio between the load current and the short-circuit current of a PV panel at maximum power point is nearly constant for different insolation (light) levels and this property is utilized in designing a simple maximum power point tracking (MPPT) controller. The controller includes a novel arrangement for sensing the short-circuit current without disturbing the operation of the PV panel and implementing MPPT. The switching losses in the inverter are reduced by using snubbers. The results obtained on an experimental converter are presented.

  9. PERFORMANCE ANALYSIS OF 2D CONVERTER BY COMBINING SR & KY CONVERTERS

    Directory of Open Access Journals (Sweden)

    V. Manoj Kumar

    2014-03-01

    Full Text Available Most of the portable equipments use battery as power source. The increasing use of low voltage portable devices and growing requirements of functionalities embedded into such devices. Thus an efficient power management technique is needed for longer battery life for them. Highly variable nature of batteries systems often require supply voltages to be both higher and lower than the battery. This is most efficiently generated by a buck-boost switching converter. But here the converter efficiency is decreased since the power loss occurs in the storage devices. Step by step, process of designing, feedback control and simulation of a novel voltage-buck boost converter, combining KY and synchronous Rectifier buck converter for battery power applications. Unlike the traditional buck–boost converter, this converter has the positive output voltage and system is stable, different from the negative output voltage and low stable of the traditional inverting buck–boost converters. Since such a converter operates in continuous conduction mode. Also it possesses the non-pulsating output current, thereby not only decreasing the current stress on the output capacitor but also reducing the output voltage ripple. Both the KY converter and the synchronous buck converter, combined into a positive buck– boost converter, uses the same power switches. Here it makes the circuit to be compact and the corresponding cost to be down. Voltage conversion ratio is 2D,so it is also called 2D converter.

  10. Electromagnetic Compatibility of Matrix Converter System

    Directory of Open Access Journals (Sweden)

    S. Fligl

    2006-12-01

    Full Text Available The presented paper deals with matrix converters pulse width modulation strategies design with emphasis on the electromagnetic compatibility. Matrix converters provide an all-silicon solution to the problem of converting AC power from one frequency to another, offering almost all the features required of an ideal static frequency changer. They possess many advantages compared to the conventional voltage or current source inverters. A matrix converter does not require energy storage components as a bulky capacitor or an inductance in the DC-link, and enables the bi-directional power flow between the power supply and load. The most of the contemporary modulation strategies are able to provide practically sinusoidal waveforms of the input and output currents with negligible low order harmonics, and to control the input displacement factor. The perspective of matrix converters regarding EMC in comparison with other types of converters is brightly evident because it is no need to use any equipment for power factor correction and current and voltage harmonics reduction. Such converter with proper control is properly compatible both with the supply mains and with the supplied load. A special digital control system was developed for the realized experimental test bed which makes it possible to achieve greater throughput of the digital control system and its variability.

  11. Underwater noise from a wave energy converter

    DEFF Research Database (Denmark)

    Tougaard, Jakob

    A recent addition to the anthropogenic sources of underwater noise is offshore wave energy converters. Underwater noise was recorded from the Wavestar wave energy converter located at Hastholm, Denmark (57°7.73´N, 8°37.23´E). The Wavestar is a full-scale test and demonstration converter...... in full operation and start and stop of the converter. Median broad band (10 Hz – 20 kHz) sound pressure level (Leq) was 123 dB re. 1 Pa, irrespective of status of the wave energy converter (stopped, running or starting/stopping). The most pronounced peak in the third-octave spectrum was in the 160 Hz...... significant noise above ambient could be detected above the 250 Hz band. The absolute increase in noise above ambient was very small. L50 third-octave levels in the four bands with the converter running were thus only 1-2 dB above ambient L50 levels. The noise recorded 25 m from the wave energy converter...

  12. Propagation characteristics of converted refracted wave and its application in static correction of converted wave

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Three-component seismic exploration through P-wave source and three-component geophone is an effective technique used in complicated reservoir exploration. In three-component seismic exploration data processing,one of the difficulties is static correction of converted wave. This paper analyzes propagation characteristics of non-converted and converted refracted waves,and discovers a favor-able condition for the formation of converted refracted wave,i.e. the velocity of overlaying medium S wave is much lower than that of underlying medium S wave. In addition,the paper proposes the static correction method of converted wave based on PPS converted refracted wave,and processes the real three-component seismic data with better results of static correction of converted wave.

  13. High-power converters and AC drives

    CERN Document Server

    Wu, Bin

    2017-01-01

    This new edition reflects the recent technological advancements in the MV drive industry, such as advanced multilevel converters and drive configurations. It includes three new chapters, Control of Synchronous Motor Drives, Transformerless MV Drives, and Matrix Converter Fed Drives. In addition, there are extensively revised chapters on Multilevel Voltage Source Inverters and Voltage Source Inverter-Fed Drives. This book includes a systematic analysis on a variety of high-power multilevel converters, illustrates important concepts with simulations and experiments, introduces various megawatt drives produced by world leading drive manufacturers, and addresses practical problems and their mitigations methods.

  14. Data Converter for Multistandard Mobile Phones

    DEFF Research Database (Denmark)

    Yurttas, Aziz; Bruun, Erik; Jensen, Rasmus Glarborg

    2004-01-01

    This paper describes an analog to digital converter (ADC) for mobile communication systems using a direct down conversion architecture. The ADC can be programmed to meet the requirements of different communication standards, including GSM (Global System for Mobile communication) and WCDMA (Wideband...... Code Division Multiple Access). The ADC is realized with a pipeline ADC architecture for WCDMA and a Sigma-Delta architecture for GSM. In order to have an optimized area and power consumption, the basic building blocks (opamps) of the converters are shared between the two converter architectures...

  15. Selective harmonic control for power converters

    DEFF Research Database (Denmark)

    Zhou, Keliang; Yang, Yongheng; Blaabjerg, Frede;

    2014-01-01

    This paper proposes an Internal Model Principle (IMP) based Selective Harmonic Controller (SHC) for power converters. The proposed SHC offers an optimal control solution for power converters to mitigate power harmonics. It makes a good trade-off among cost, complexity and performance. It has high...... accuracy and fast transient response, and it is cost-effective, easy for real-time implementation, and compatible for design rules-of-thumb. An application on a three-phase PWM converter has confirmed the effectiveness of the proposed control scheme in terms of harmonic mitigation....

  16. Time interleaved counter analog to digital converters

    OpenAIRE

    Danesh, Seyed Amir Ali

    2011-01-01

    The work explores extending time interleaving in A/D converters, by applying a high-level of parallelism to one of the slowest and simplest types of data-converters, the counter ADC. The motivation for the work is to realise high-performance re-configurable A/D converters for use in multi-standard and multi-PHY communication receivers with signal bandwidths in the 10s to 100s of MHz. The counter ADC requires only a comparator, a ramp signal, and a digital counter, where the ...

  17. New PWM switched-mode converter topologies

    Science.gov (United States)

    Hua, Gui-Chao; Huang, Shi-Peng

    Two augmented switching cells are proposed from which four novel topologies can be derived: an augmented buck converter, an augmented boost converter, a novel switching power amplifier, and a novel switching controlled rectifier. The augmented buck and the augmented boost converters realize higher step-down and step-up ratios, respectively, under a given switch duty ratio by proper design of the turn ratios of the transformer and coupled inductor. The switching power amplifier achieves four-quadrant output by the use of two bidirectional current switches and a single power supply, while the inverse converter can be used as a switching controlled rectifier. The experimental verification of the power amplifier is presented.

  18. "Forback" Dc-To-Dc Converters

    Science.gov (United States)

    Lukemire, Alan T.

    1992-01-01

    Dc-to-dc power-converter circuits called "forback" resemble circuits of standard configurations called "forward", "flyback", and "Cuk". Circuit employs minor modifications to existing topologies, combines advantages, while eliminating disadvantages, of older circuits.

  19. A three-port direct current converter

    DEFF Research Database (Denmark)

    2016-01-01

    The three-port direct current converter comprising: at least one input direct current source; at least one storage battery; a primary side circuit; a secondary side circuit; a first single magnetic component shared by the primary side circuit and the secondary side circuit, wherein the primary side...... circuit comprises a connection between the at least one input direct current source and the at least one storage battery, the primary side circuit configured for operating as a buck converter; a second magnetic component serially coupled to the first single magnetic component, wherein the first and second...... magnetic components are configured to perform a voltage step-up, wherein the secondary side circuit comprises a connection between the at least one storage battery and at least one load, the secondary side configured for operating as a tapped boost converter; wherein the three-port direct current converter...

  20. Interface of magnetoresistive converter of active power

    Directory of Open Access Journals (Sweden)

    A. I. Vytiaganets

    2009-10-01

    Full Text Available The vehicle and programmatic interfaces of magnetoresistive converter of active power are considered, the results of statistical treatment of the multiple measuring of active-power are analysed.

  1. Catalytic converters as a source of platinum

    Directory of Open Access Journals (Sweden)

    A. Fornalczyk

    2011-10-01

    Full Text Available The increase of Platinum Group Metals demand in automotive industry is connected with growing amount of cars equipped with the catalytic converters. The paper presents the review of available technologies during recycling process. The possibility of removing platinum from the used catalytic converters applying pyrometallurgical and hyrdometallurgical methods were also investigated. Metals such as Cu, Pb, Ca, Mg, Cd were used in the pyrometallurgical research (catalytic converter was melted with Cu, Pb and Ca or Mg and Cd vapours were blown through the whole carrier. In hydrometallurgical research catalytic converters was dissolved in aqua regia. Analysis of Pt contents in the carrier before and after the process was performed by means of atomic absorption spectroscopy. Obtained result were discussed.

  2. Reliability of power electronic converter systems

    CERN Document Server

    Chung, Henry Shu-hung; Blaabjerg, Frede; Pecht, Michael

    2016-01-01

    This book outlines current research into the scientific modeling, experimentation, and remedial measures for advancing the reliability, availability, system robustness, and maintainability of Power Electronic Converter Systems (PECS) at different levels of complexity.

  3. State estimation for wave energy converters

    Energy Technology Data Exchange (ETDEWEB)

    Bacelli, Giorgio; Coe, Ryan Geoffrey

    2017-04-01

    This report gives a brief discussion and examples on the topic of state estimation for wave energy converters (WECs). These methods are intended for use to enable real-time closed loop control of WECs.

  4. New design trends in photovoltaic converters

    OpenAIRE

    Van den Bossche, Alex

    2013-01-01

    The reason to look at new trends in PV converters is that, in the total cost of ownership the converter is more expensive than the PV panel. Another trend is that one uses them without transformer to increase efficiency, but one has to take into account safety. One can increase the switching frequency and at the same time reducing the switching losses using SiC components, but still good cost effective solutions can be made with Si-IGBTs.

  5. Industrial application, 1MHz, quasi resonant converter

    OpenAIRE

    Carrasco Solís, Juan Manuel; Pérez Ridao, Francisco; Quero Reboul, José Manuel; Janer Jiménez, Carlos; García Franquelo, Leopoldo

    1993-01-01

    An industrial multi-output QRC converter is presented. Its main designing constraints are low cost, small in size, reduced EMI and EMC, high efficiency and severe dynamic behaviour in all outputs. Accomplishing this last restriction proved to be a difficult task. This has been done by means of a classical controller and cross regulation. The actual performance was tested on a 1MHz prototype rated at 50W. The low cost developed converter is characterized by its simplicity of design and operati...

  6. AC – AC Converters for UPS

    Directory of Open Access Journals (Sweden)

    Rusalin Lucian R. Păun

    2008-05-01

    Full Text Available This paper propose a new control technique forsingle – phase AC – AC converters used for a on-line UPSwith a good dynamic response, a reduced-partscomponents, a good output characteristic, a good powerfactorcorrection(PFC. This converter no needs anisolation transformer. A power factor correction rectifierand an inverter with the proposed control scheme has beendesigned and simulated using Caspoc2007, validating theconcept.

  7. Switching power converters medium and high power

    CERN Document Server

    Neacsu, Dorin O

    2013-01-01

    An examination of all of the multidisciplinary aspects of medium- and high-power converter systems, including basic power electronics, digital control and hardware, sensors, analog preprocessing of signals, protection devices and fault management, and pulse-width-modulation (PWM) algorithms, Switching Power Converters: Medium and High Power, Second Edition discusses the actual use of industrial technology and its related subassemblies and components, covering facets of implementation otherwise overlooked by theoretical textbooks. The updated Second Edition contains many new figures, as well as

  8. Local Bifurcations in DC-DC Converters

    OpenAIRE

    2012-01-01

    Three local bifurcations in DC-DC converters are reviewed. They are period-doubling bifurcation, saddle-node bifurcation, and Neimark bifurcation. A general sampled-data model is employed to study the types of loss of stability of the nominal (periodic) solution and their connection with local bifurcations. More accurate prediction of instability and bifurcation than using the averaging approach is obtained. Examples of bifurcations associated with instabilities in DC-DC converters are given.

  9. LHC Power Converters: A Precision Game

    CERN Multimedia

    2001-01-01

    The LHC test-bed, String 2, is close to commissioning and one important element to get a first chance to prove what it can do is the power converter system. In String 2 there are 16 converters, in the full LHC there will be almost 1800. This article takes a look at what is so special about the power converters for the LHC. The 13 000 Amps power converters with the watercooled cables going to the String 2 feedboxes. The LHC's superconducting magnets will be the pinnacle of high technology. But to work, they'll need the help of high-precision power converters to supply them with extremely stable DC current. Perfection will be the name of the game, with an accuracy of just 1-2 parts per million (ppm) required. LEP, for the sake of comparison, could live with 10-20 ppm. The LHC's power converters will be very different from those of LEP or the SPS since the new accelerator's magnets are mostly superconducting. That means that they require much higher currents at a lower voltage since superconductors have no re...

  10. Low arc drop hybrid mode thermionic converter

    Science.gov (United States)

    Shimada, K.

    1977-01-01

    The hybrid mode operation for the reduction of plasma drops is being investigated. This report discusses the results obtained from two molybdenum emitter converters. One converter had a molybdenum collector and the other a nickel collector. The molybdenum collector converter was operated in a hybrid mode (at an interelectrode distance of 1.7 mm) and produced a minimum barrier index of 1.96 eV at an emitter temperature of 1500 K. The arc drop was calculated to be 0.14 eV, using the published results for a molybdenum collector. On the other hand, the nickel collector converter was operated in a conventional ignited mode (at an interelectrode distance of 0.5 mm) and produced a minimum barrier index of 2.1 eV at an emitter temperature of 1700 K. It is tentatively concluded that a large-gap operation of the hybrid mode converter permits the diffusion of cesium ions to a distance in the order of one millimeter for an effective neutralization of electron space charge. By employing a low work function collector (1.55 eV) in a hybrid mode converter with an arc drop of 0.14 eV, it appears that a barrier index as low as 1.69 eV could be achieved.

  11. Simulation of Multi output Fly back Converter with Integrated Auxiliary Buck Converter with reduced components

    Directory of Open Access Journals (Sweden)

    J.KOMATHI

    2015-04-01

    Full Text Available The fly back converter has been widely used for multi outputs due to the simple structure and low cost in low-power applications. This paper presents a new multi output converter. It consists of a half-bridge inverter with boost converter in primary side and a fly back rectifier that is integrated with an auxiliary buck converter in secondary side. The boost converter is used to generate high voltage dc from Low voltage PV cells. The primary switches control the main output voltage and the secondary synchronous switches control the auxiliary output voltage. The main advantages of the proposed converter are that the transformer size can be reduced due to the less magnetizing offset current, all the power switches including synchronous ones can achieve the zero-voltage switching (ZVS and it has no output cross regulation problems. The circuit is simulated using MATLAB. The performance is verified with simulation results.

  12. Materials technology for Stirling space power converters

    Science.gov (United States)

    Baggenstoss, William; Mittendorf, Donald

    1992-01-01

    This program was conducted in support of the NASA LeRC development of the Stirling power converter (SPC) for space power applications. The objectives of this contract were: (1) to perform a technology review and analyses to support the evaluation of materials issues for the SPC; (2) to evaluate liquid metal compatibility issues of the SPC; (3) to evaluate and define a transient liquid phase diffusion bonding (TLPDB) process for the SPC joints to the Udimet 720 heater head; and (4) to evaluate alternative (to the TLPDB) joining techniques. In the technology review, several aspects of the current Stirling design were examined including the power converter assembly process, materials joining, gas bearings, and heat exchangers. The supporting analyses included GLIMPS power converter simulation in support of the materials studies, and system level analysis in support of the technology review. The liquid metal compatibility study evaluated process parameters for use in the Stirling power converter. The alternative joining techniques study looked at the applicability of various joining techniques to the Stirling power converter requirements.

  13. Efficiency of Thermionic and Thermoelectric Converters

    Science.gov (United States)

    Gerstenmaier, York Christian; Wachutka, Gerhard

    2007-02-01

    Thermoelectric and thermionic converters — also in micro- and nano-meter design — are considered for power generation and cooling applications. The potential of thermionic vacuum gap converters is investigated precisely by a new advanced theory with inclusion of backward currents from the 2nd electrode, losses due to thermal radiation and ohmic resistance in the electrodes, tunneling through the gap, image forces, and space charge effects. The efficiency of nano-meter gap thermionic converters is by far higher than for thermoelectric devices (including nano-structured superlattices) for operating temperatures above 800°K, however, there is no chance of realization with today's technology. For a vacuum gap width of about 1 μm the performance is higher than for hypothetical bulk- thermoelectric generators (TEGs) with ZT = 1 for T > 1000°K and also higher than for hypothetical nano-structured superlattices (ZT = 2.4) for T > 1200°K. A thermionic converter with gap width of 5μm has lower performance than a TEG with ZT = 1, however, also operates at T > 1200°K. Reasonable performance of thermionic converters at T ⩽ 500°K necessitates materials with workfunctions ⩽ 0.5 eV.

  14. Understanding delta-sigma data converters

    CERN Document Server

    Pavan, Shanti; Temes, Gabor C

    2017-01-01

    This new edition introduces novel analysis and design techniques for delta-sigma (ΔΣ) converters in physical and conceptual terms, and includes new chapters that explore developments in the field over the last decade. This book explains the principles and operation of delta-sigma analog-to-digital converters (ADCs) in physical and conceptual terms in accordance with the most recent developments in the field. The interest of ΔΣ converter designers has shifted significantly over the past decade, due to many new applications for data converters at the far ends of the frequency spectrum. Continuous-time delta-sigma A/D converters with GHz clocks, of both lowpass and bandpass types, are required for wireless applications. At the other extreme, multiplexed ADCs with very narrow (sometimes 10 Hz wide) signal bandwidths, but very high accuracy are needed in the interfaces of biomedical and environmental sensors. To reflect the changing eeds of designers, the second edition includes significant new material on bo...

  15. A linear temperature-to-frequency converter

    DEFF Research Database (Denmark)

    Løvborg, Leif

    1965-01-01

    The possibility of converting temperature into a frequency signal by means of a thermistor which is part of the frequency-determining network of an RC oscillator is investigated. It is shown that a temperature - frequency characteristic which has a point of inflection may be realized, and that th......The possibility of converting temperature into a frequency signal by means of a thermistor which is part of the frequency-determining network of an RC oscillator is investigated. It is shown that a temperature - frequency characteristic which has a point of inflection may be realized......, and that the maximum value of the temperature-frequency coefficient beta in this point is-1/3 alpha, where a is the temperature coefficient of the thermistor at the corresponding temperature. Curves showing the range in which the converter is expected to be linear to within plusmn0.1 degC are given. A laboratory...

  16. Converters for Distributed Power Generation Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Yang, Yongheng

    2015-01-01

    Power electronics technology has become the enabling technology for the integration of distributed power generation systems (DPGS) such as offshore wind turbine power systems and commercial photovoltaic power plants. Depending on the applications, a vast array of DPGS-based power converter...... presents an overview of the power converters for the DPGS, mainly based on wind turbine systems and photovoltaic systems, covering a wide range of applications. Moreover, the modulation schemes and interfacing power filters for the power converters are also exemplified. Finally, the general control...... topologies has been developed and more are coming into the market in order to achieve an efficient and reliable power conversion from the renewables. In addition, stringent demands from both the distribution system operators and the consumers have been imposed on the renewable-based DPGS. This article...

  17. CMOS Integrated Capacitive DC-DC Converters

    CERN Document Server

    Van Breussegem, Tom

    2013-01-01

    This book provides a detailed analysis of all aspects of capacitive DC-DC converter design: topology selection, control loop design and noise mitigation. Readers will benefit from the authors’ systematic overview that starts from the ground up, in-depth circuit analysis and a thorough review of recently proposed techniques and design methodologies.  Not only design techniques are discussed, but also implementation in CMOS is shown, by pinpointing the technological opportunities of CMOS and demonstrating the implementation based on four state-of-the-art prototypes.  Provides a detailed analysis of all aspects of capacitive DC-DC converter design;  Analyzes the potential of this type of DC-DC converter and introduces a number of techniques to unleash their full potential; Combines system theory with practical implementation techniques; Includes unique analysis of CMOS technology for this application; Provides in-depth analysis of four fabricated prototypes.

  18. External ionization mechanisms for advanced thermionic converters

    Science.gov (United States)

    Hatziprokopiou, M. E.

    Ion generation and recombination mechanisms in the cesium plasma were investigated as they pertain to the advanced mode thermionic energy converters. The changes in plasma density and temperature within the converter were studied under the influence of several promising auxiliary ionization candidate sources. Three novel approaches of external cesium ion generation were investigated in some detail, namely vibrationally excited N2 as an energy source of ionization of Cs ions in a DC discharge, microwave power as a means of resonant sustenance of the cesium plasma, and ion generation in a pulse N2-Cs mixture. The experimental data obtained and discussed in this work show that all three techniques--i.e. the non-LTE high-voltage pulsing, the energy transfer from vibrationally excited diatomic gases, and the external pumping with a microwave power--have considerable promise as schemes in auxiliary ion generation applicable to the advanced thermionic energy converter.

  19. Data Converter for Multistandard Mobile Phones

    DEFF Research Database (Denmark)

    Yurttas, Aziz; Bruun, Erik; Jensen, Rasmus Glarborg

    2004-01-01

    This paper describes an analog to digital converter (ADC) for mobile communication systems using a direct down conversion architecture. The ADC can be programmed to meet the requirements of different communication standards, including GSM (Global System for Mobile communication) and WCDMA (Wideband...... Code Division Multiple Access). The ADC is realized with a pipeline ADC architecture for WCDMA and a Sigma-Delta architecture for GSM. In order to have an optimized area and power consumption, the basic building blocks (opamps) of the converters are shared between the two converter architectures....... The entire ADC consumes about 5.5 mW and occupies an active area of about 0.36 mm(2). A test circuit has been developed and fabricated and measurements show that both the required programmability and the required performance can be obtained using the proposed configurations....

  20. Power system applications for PASC converter systems

    Energy Technology Data Exchange (ETDEWEB)

    Donnelly, M.K. [Pacific Northwest Lab., Richland, WA (United States); Johnson, R.M. [Montana State Univ., Bozeman, MT (United States)

    1994-04-01

    This paper shows, using computer EMTP simulations, some preliminary results of applying pulse amplitude synthesis and control (PASC) technology to single-source level voltage converter system. The method can be applied to any single terminal pair source with appropriate modifications in power extraction interface and computer control program to match source and load impedance characteristics. The PASC realization as discussed here employs banks of transformers, one bank per phase, in which the primaries are connected in parallel through a switch matrix to the dc source. Two opposite polarity primaries per transformer are pulsed alternatively in time to produce an oscillatory sinusoidal output waveform. PASC conversion system capabilities to produce both leading and lagging power factor power output in single-phase and three-phase {Delta} or Y configurations are illustrated. EMTP simulations are used to demonstrate the converter capabilities. Also included are discussions regarding harmonics and potential control strategies to adapt the converter to an application or to minimize harmonics.

  1. Self-oscillating resonant power converter

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to resonant power converters and inverters comprising a self-oscillating feedback loop coupled from a switch output to a control input of a switching network comprising one or more semiconductor switches. The self-oscillating feedback loop sets a switching frequency...... of the power converter and comprises a first intrinsic switch capacitance coupled between a switch output and a control input of the switching network and a first inductor. The first inductor is coupled in-between a first bias voltage source and the control input of the switching network and has...... a substantially fixed inductance. The first bias voltage source is configured to generate an adjustable bias voltage applied to the first inductor. The output voltage of the power converter is controlled in a flexible and rapid manner by controlling the adjustable bias voltage....

  2. High Efficiency Reversible Fuel Cell Power Converter

    DEFF Research Database (Denmark)

    Pittini, Riccardo

    The large scale integration of renewable energy sources requires suitable energy storage systems to balance energy production and demand in the electrical grid. Bidirectional fuel cells are an attractive technology for energy storage systems due to the high energy density of fuel. Compared...... entitled "High Efficiency Reversible Fuel Cell Power Converter" and it presents the design of a high efficiency dc-dc converter developed and optimized for bidirectional fuel cell applications. First, a brief overview of fuel cell and energy storage technologies is presented. Different system topologies...... to traditional unidirectional fuel cell, bidirectional fuel cells have increased operating voltage and current ranges. These characteristics increase the stresses on dc-dc and dc-ac converters in the electrical system, which require proper design and advanced optimization. This work is part of the PhD project...

  3. Single phase AC-DC power factor corrected converter with high frequency isolation using buck converter

    Directory of Open Access Journals (Sweden)

    R. Ramesh,

    2014-03-01

    Full Text Available Single phase ac-dc converters having high frequency isolation are implemented in buck, boost, buck-boost configuration with improving the power quality in terms of reducing the harmonics of input current. The paperpropose the circuit configuration, control mechanism, and simulation result for the single phase ac-dc converter.

  4. Dual Converter Fed Open-End Transformer Topology with Parallel Converters and Integrated Magnetics

    DEFF Research Database (Denmark)

    Gohil, Ghanshyamsinh Vijaysinh; Bede, Lorand; Teodorescu, Remus

    2016-01-01

    A converter system for high power applications, connected to a medium-voltage network using a stepup transformer, is presented in this paper. The converterside winding of the transformer is configured as an openend and both the ends of the windings are fed from two different converter groups. Each...

  5. Si Bule Masuk Islam: Western Converts to Islam in Indonesia - more than just Converts of Convenience?

    Directory of Open Access Journals (Sweden)

    M. A. Kevin Brice

    2015-04-01

    Full Text Available In discussing converts to Islam, two different types of converts are often identified based on the reason for conversion: converts of convenience and converts of conviction. The common view is that in most (if not all cases, conversion to Islam in Indonesia by Westerners is about facilitating marriage and so the converts should be classified as converts of convenience. Evidence of the commonality of this view is considered by reference to advice offered to Westerners about marriage to Indonesians on specialist web sites and examples of coverage of the topic in Indonesian social media. By considering a number of brief case studies, the common view is challenged. The binary of “convert of convenience” versus “convert of conviction” is revisited to suggest that individuals may move between the types over a period of time. Finally the paper will consider whether there is anything about Islam in Indonesia which contributes to the phenomenon of “transnational” conversion by Westerners in Indonesia.DOI: 10.15408/sdi.v22i1.1386

  6. Solar energy converter using surface plasma waves

    Science.gov (United States)

    Anderson, L. M. (Inventor)

    1984-01-01

    Sunlight is dispersed over a diffraction grating formed on the surface of a conducting film on a substrate. The angular dispersion controls the effective grating period so that a matching spectrum of surface plasmons is excited for parallel processing on the conducting film. The resulting surface plasmons carry energy to an array of inelastic tunnel diodes. This solar energy converter does not require different materials for each frequency band, and sunlight is directly converted to electricity in an efficient manner by extracting more energy from the more energetic photons.

  7. Modeling and Simulation of Matrix Converter

    DEFF Research Database (Denmark)

    Liu, Fu-rong; Klumpner, Christian; Blaabjerg, Frede

    2005-01-01

    This paper discusses the modeling and simulation of matrix converter. Two models of matrix converter are presented: one is based on indirect space vector modulation and the other is based on power balance equation. The basis of these two models is• given and the process on modeling is introduced...... in details. The results of simulations developed for different researches reveal that different mdel may be suitable for different purpose, thus the model should be chosen different carefully. Some details and tricks in modeling are also introduced which give a reference for further research....

  8. Combination solar photovoltaic heat engine energy converter

    Science.gov (United States)

    Chubb, Donald L.

    1987-01-01

    A combination solar photovoltaic heat engine converter is proposed. Such a system is suitable for either terrestrial or space power applications. The combination system has a higher efficiency than either the photovoltaic array or the heat engine alone can attain. Advantages in concentrator and radiator area and receiver mass of the photovoltaic heat engine system over a heat-engine-only system are estimated. A mass and area comparison between the proposed space station organic Rankine power system and a combination PV-heat engine system is made. The critical problem for the proposed converter is the necessity for high temperature photovoltaic array operation. Estimates of the required photovoltaic temperature are presented.

  9. Metamaterial polarization converter analysis: limits of performance

    DEFF Research Database (Denmark)

    Markovich, Dmitry L.; Andryieuski, Andrei; Zalkovskij, Maksim;

    2013-01-01

    In this paper, we analyze the theoretical limits of a metamaterial-based converter with orthogonal linear eigenpolarizations that allow linear-to-elliptical polarization transformation with any desired ellipticity and ellipse orientation. We employ the transmission line approach providing a needed...... and a single layer with a ground plane can have 100 % polarization conversion efficiency. We tested our conclusions numerically reaching the designated limits of efficiency using a simple metamaterial design. Our general analysis provides useful guidelines for the metamaterial polarization converter design...

  10. Is China Ready for Full Yuan Convertibility?

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Although China has made headway in reforming the exchange rate regime of its currency,the yuan,and expanding the use of it in cross-border trade during the past year,the yuan is far from fully convertible.Huang Yiping,a professor at the National School of Development of Peking University,said in an article for Beijing Review that China has the conditions for capital account liberalization and should strive for basic convertibility within five years. Edited excerpts follow

  11. Generalized modular multilevel converter and modulation

    DEFF Research Database (Denmark)

    Liu, Hui; Loh, Poh Chiang; Blaabjerg, Frede

    2014-01-01

    Modular multilevel converter (MMC) has gained popularity recently with its modulation, capacitor voltage balancing and circulating current issues widely discussed. Contributing to this effort, a study is presented here to show how the MMC topology can be derived from the viewpoint of two series...... converters regulating a power grid. The generalized topology derived and notated as GMMC can then be altered to create various types of MMC, including the traditional topology that is presently well-known. This effort has not been previously discussed, and may smoothen the understanding of MMC operation...

  12. Efficient, lightweight dc/dc switching converter

    Science.gov (United States)

    Cuk, S.; Middlebrook, R. D.

    1981-01-01

    Converters have input properties of boost power stage and output properties of buck power stage, yet they perform general conversion function with high efficiency. Other features include non-pulsating input/output currents, use of capacitive energy transfer, low output voltage ripple, reduced EMI, and small size.

  13. Power electronics converters for wind turbine systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Liserre, Marco; Ma, Ke

    2011-01-01

    The steady growth of installed wind power which reached 200 GW capacity in 2010, together with the up-scaling of the single wind turbine power capability - 7 MW’s has been announced by manufacturers - has pushed the research and development of power converters towards full scale power conversion,...

  14. Power Electronics Converters for Wind Turbine Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Liserre, Marco; Ma, Ke

    2012-01-01

    The steady growth of installed wind power together with the upscaling of the single wind turbine power capability has pushed the research and development of power converters toward full-scale power conversion, lowered cost pr kW, increased power density, and also the need for higher reliability. ...

  15. China to Gradually Make Capital Account Convertible

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ China is pushing forward its currency Renminbi (RMB)'s capital account convertibility gradually and in a stable manner, said an official with the State Administration of Foreign Exchange (SAFE), ruling out both an adventurous leap and conservative cautiousness, according to a report of Xinhua on April 12.

  16. China to Gradually Make Capital Account Convertible

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

      China is pushing forward its currency Renminbi (RMB)'s capital account convertibility gradually and in a stable manner, said an official with the State Administration of Foreign Exchange (SAFE), ruling out both an adventurous leap and conservative cautiousness, according to a report of Xinhua on April 12.……

  17. Power electronics converters for wind turbine systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Liserre, Marco; Ma, Ke

    2011-01-01

    The steady growth of installed wind power which reached 200 GW capacity in 2010, together with the up-scaling of the single wind turbine power capability - 7 MW’s has been announced by manufacturers - has pushed the research and development of power converters towards full scale power conversion,...

  18. Mathematical modeling of the flash converting process

    Energy Technology Data Exchange (ETDEWEB)

    Sohn, H.Y.; Perez-Tello, M.; Riihilahti, K.M. [Utah Univ., Salt Lake City, UT (United States)

    1996-12-31

    An axisymmetric mathematical model for the Kennecott-Outokumpu flash converting process for converting solid copper matte to copper is presented. The model is an adaptation of the comprehensive mathematical model formerly developed at the University of Utah for the flash smelting of copper concentrates. The model incorporates the transport of momentum, heat, mass, and reaction kinetics between gas and particles in a particle-laden turbulent gas jet. The standard k-{epsilon} model is used to describe gas-phase turbulence in an Eulerian framework. The particle-phase is treated from a Lagrangian viewpoint which is coupled to the gas-phase via the source terms in the Eulerian gas-phase governing equations. Matte particles were represented as Cu{sub 2}S yFeS, and assumed to undergo homogeneous oxidation to Cu{sub 2}O, Fe{sub 3}O{sub 4}, and SO{sub 2}. A reaction kinetics mechanism involving both external mass transfer of oxygen gas to the particle surface and diffusion of oxygen through the porous oxide layer is proposed to estimate the particle oxidation rate Predictions of the mathematical model were compared with the experimental data collected in a bench-scale flash converting facility. Good agreement between the model predictions and the measurements was obtained. The model was used to study the effect of different gas-injection configurations on the overall fluid dynamics in a commercial size flash converting shaft. (author)

  19. Development of the Wave Energy Converter

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter; Sørensen, Hans Christian

    2000-01-01

    The development of the wave energy converter Wave Dragon (WD) is presented. The WD is based on the overtopping principle. Initially a description of the WD is given. Then the development over time in terms of the various research and development projects working with the concept is described...

  20. Aquabuoy Wave Energy Converter

    DEFF Research Database (Denmark)

    Vicinanza, Diego; Margheritini, Lucia; Frigaard, Peter

    The work reported here is part of the contract agreement between the Finavera Renewables Ocean Energy Ltd. and the Department of Civil Engineering Hydraulics and Coastal Engineering Laboratory to instrument a model in scale 1:10 to prototype of the AquaBuOY (AB) wave energy converter and to analyse...

  1. Fast Constant Weight Codeword to Index Converter

    Science.gov (United States)

    2011-08-01

    is achievable; a 64-out- of-128 bit converter uses only 9% of the available ALMs. The large values of n required special Verilog programming. For...n r ) in a MATLAB program and wrote it to a header file that was included in the Verilog code. III. COMPLEX DISJOINT DECOMPOSITION SOLUTION It can

  2. Low-power variable frequency PFC converters

    Energy Technology Data Exchange (ETDEWEB)

    Li Yani; Yang Yintang; Zhu Zhangming, E-mail: yanili@mail.xidian.edu.c [Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices of the Ministry of Education, Institute of Microelectronics, Xidian University, Xi' an 710071 (China)

    2010-01-15

    Based on the SinoMOS 1 {mu}m 40 V CMOS process, a novel power factor contention (PFC) converter with a low-power variable frequency function is presented. The circuit introduces a multi-vector error amplifier and a programmable oscillator to achieve frequency modulation, which provides a rapid dynamic response and precise output voltage clamping with low power in the entire load. According to the external load variation, the system can modulate the circuit operating frequency linearly, thereby ensuring that the PFC converter can work in frequency conversion-mode. Measured results show that the normal operating frequency of the PFC converter is 5-6 kHz, the start-up current is 36 {mu}A, the stable operating current is only 2.43 mA, the efficiency is 97.3%, the power factor (PF) is 0.988, THD is 3.8%, the load adjust rate is 3%, and the linear adjust rate is less than 1%. Both theoretical and practical results reveal that the power consumption of the whole supply system is reduced efficiently, especially when the load varies. The active die area of the PFC converter chip is 1.61 x 1.52 mm{sup 2}. (semiconductor integrated circuits)

  3. Oxygen activity measurements in simulated converter matte

    CSIR Research Space (South Africa)

    Tshilombo, KG

    2007-01-01

    Full Text Available to the composition of the gas atmosphere over the melt. The measured oxygen activity was generally close to that predicted by FactSage calculations. This indicates that such oxygen activity measurements could be useful to monitor iron removal during converting...

  4. Online Scheduling in Distributed Message Converter Systems

    NARCIS (Netherlands)

    Risse, Thomas; Wombacher, Andreas; Surridge, Mike; Taylor, Steve; Aberer, Karl

    2001-01-01

    The optimal distribution of jobs among hosts in distributed environments is an important factor to achieve high performance. The optimal strategy depends on the application. In this paper we present a new online scheduling strategy for distributed EDI converter system. The strategy is based on the B

  5. Converting Student Support Services to Online Delivery.

    Science.gov (United States)

    Brigham, David E.

    2001-01-01

    Uses a systems framework to analyze the creation of student support services for distance education at Regents College: electronic advising, electronic peer network, online course database, online bookstore, virtual library, and alumni services website. Addresses the issues involved in converting distance education programs from print-based and…

  6. Online Scheduling in Distributed Message Converter Systems

    NARCIS (Netherlands)

    Risse, Thomas; Wombacher, Andreas; Surridge, Mike; Taylor, Steve; Aberer, Karl

    2001-01-01

    The optimal distribution of jobs among hosts in distributed environments is an important factor to achieve high performance. The optimal strategy depends on the application. In this paper we present a new online scheduling strategy for distributed EDI converter system. The strategy is based on the B

  7. Online Scheduling in Distributed Message Converter Systems

    NARCIS (Netherlands)

    Risse, Thomas; Wombacher, Andreas; Surridge, Mike; Taylor, Steve; Aberer, Karl

    The optimal distribution of jobs among hosts in distributed environments is an important factor to achieve high performance. The optimal strategy depends on the application. In this paper we present a new online scheduling strategy for distributed EDI converter system. The strategy is based on the

  8. Near-Shore Floating Wave Energy Converters

    DEFF Research Database (Denmark)

    Ruol, Piero; Zanuttigh, Barbara; Martinelli, Luca

    2011-01-01

    Aim of this note is to analyse the possible application of a Wave Energy Converter (WEC) as a combined tool to protect the coast and harvest energy. Physical model tests are used to evaluate wave transmission past a near-shore floating WEC of the wave activated body type, named DEXA. Efficiency...

  9. Hybrid switch for resonant power converters

    Science.gov (United States)

    Lai, Jih-Sheng; Yu, Wensong

    2014-09-09

    A hybrid switch comprising two semiconductor switches connected in parallel but having different voltage drop characteristics as a function of current facilitates attainment of zero voltage switching and reduces conduction losses to complement reduction of switching losses achieved through zero voltage switching in power converters such as high-current inverters.

  10. A New Hard Switching Bidirectional Converter With High Power Density

    Directory of Open Access Journals (Sweden)

    Bahador Fani

    2010-01-01

    Full Text Available In this paper, a new isolated dc-dc bidirectional converter is proposed. This converter consists of two transformers (flyback and forward and only one switch in primary side and one switch in secondary side of transformers. In this converter energy transfers to the output in both on and off switch states so power density of this converter is high This converter controlled by PWM signal. Also this converter operates over a wide input voltage range. Theoretical analysis is presented and computer simulation and experimental results verify the converter analysis.

  11. Bidirectional converter interface for a battery energy storage test bench

    DEFF Research Database (Denmark)

    Trintis, Ionut; Thomas, Stephan; Blank, Tobias;

    2011-01-01

    This paper presents the bidirectional converter interface for a 6 kV battery energy storage test bench. The power electronic interface consists a two stage converter topology having a low voltage dc-ac grid connected converter and a new dual active bridge dc-dc converter with high transformation...... ratio. The dc-dc converter controls the battery charge/discharge current while the grid converter controls the common dc-link voltage and the grid current. The applied control structures and the hardware implementation of both converters are presented, together with their interaction. Experimental...

  12. Bidirectional converter interface for a battery energy storage test bench

    DEFF Research Database (Denmark)

    Trintis, Ionut; Thomas, Stephan; Blank, Tobias

    2011-01-01

    This paper presents the bidirectional converter interface for a 6 kV battery energy storage test bench. The power electronic interface consists a two stage converter topology having a low voltage dc-ac grid connected converter and a new dual active bridge dc-dc converter with high transformation...... ratio. The dc-dc converter controls the battery charge/discharge current while the grid converter controls the common dc-link voltage and the grid current. The applied control structures and the hardware implementation of both converters are presented, together with their interaction. Experimental...

  13. Multi-output DC-DC converters based on diode-clamped converters configuration

    DEFF Research Database (Denmark)

    Nami, A.; Zare, F.; Ghosh, A.;

    2010-01-01

    for a diode-clamed inverter in the grid connection systems, where boosting low rectified output-voltage and series DC link capacitors is required. To verify the proposed topology, steady-state and dynamic analyses of a MOB converter are examined. A simple control strategy has been proposed to demonstrate...... the performance of the proposed topology for a double-output boost converter. The topology and its control strategy can easily be extended to offer multiple outputs. Simulation and experimental results are presented to show the validity of the control strategy for the proposed converter....

  14. Emissions Tests Of Two Dc-To-Dc Converters

    Science.gov (United States)

    Mclyman, W. T.

    1992-01-01

    Report describes tests to characterize unwanted electric and magnetic fields, at frequencies up to few megahertz, radiated by two dc-to-dc converters, one 20-kHz square-wave converter; the other, a 33-kHz sine-wave converter. Part of effort to develop "quiet" power converter for use aboard spacecraft. Converter required to interfere minimally with delicate instruments measuring electric and magnetic fields.

  15. Coordinated Control of Wave Energy Converters Subject to Motion Constraints

    OpenAIRE

    2016-01-01

    In this paper, a generic coordinated control method for wave energy converters is proposed, and the constraints on motion amplitudes and the hydrodynamic interaction between converters are considered. The objective of the control problem is to maximize the energy converted from ocean waves, and this is achieved by coordinating the power take-off (PTO) damping of each wave energy converter in the frequency domain in each sea state. In a case study, a wave energy farm consisting of four convert...

  16. Research on Converter Valve Overvoltage Mechanism and Calculation Conditions of ± 800 kV Converter Station

    Institute of Scientific and Technical Information of China (English)

    WANG Dongju; DENG Xu; ZHOU Hao; CHEN Xilei; XU Anwen; SHEN Yang

    2012-01-01

    The thyristor converter valve is the key equipment of commutation in ultra high voltage direct current (UHVDC) transmission systems. Owing to the limited voltage and current overload capacity, any transient overvoltage may cause permanent damage to the thyristor converter valve. In order to specify the converter valves' overvoltage levels of the ±800 kV UHVDC transmission system, the mechanisms of its generation and development are discussed in detail, from which the calculation conditions for the highest stresses of the converter valves are given. Finally, the converter valve's overvoltage of Xiluodu UHV converter station is simulated. The research results show that the overvoltages of the converter valves in the upper 3-pulse group of the high voltage(HV) and low voltage(LV) 12-pulse converter are generated jointly by the DC line voltage and the converter transformer's voltage at its valve side. Calculation conditions for this overvoltage are: DC system in bipolar operation mode, converter station operating as rectifier, maximum DC system operating voltage, minimum DC current, minimum AC system voltage of the converter station. Furthermore, the other converter valves' overvoltage is caused by the phase-to-phase switching surge generated at the converter station's AC side, penetrating into the valve hall. Overall, the maximum overvoltages of Xiluodu converter station in the upper 3-pulse group of the HV and LV 12-pulse converter are 379.1 kV and 384.9 kV, for other converter valves the maximum overvoltage is 375.3 kV.

  17. Imbalance between pulmonary angiotensin-converting enzyme and angiotensin-converting enzyme 2 activity in acute respiratory distress syndrome

    NARCIS (Netherlands)

    Wosten-van Asperen, Roelie M.; Bos, Albert; Bem, Reinout A.; Dierdorp, Barbara S.; Dekker, Tamara; van Goor, Harry; Kamilic, Jelena; van der Loos, Chris M.; van den Berg, Elske; Bruijn, Martijn; van Woensel, Job B.; Lutter, Rene

    2013-01-01

    Objective: Angiotensin-converting enzyme and its effector peptide angiotensin II have been implicated in the pathogenesis of acute respiratory distress syndrome. Recently, angiotensin-converting enzyme 2 was identified as the counter-regulatory enzyme of angiotensin-converting enzyme that converts

  18. Imbalance between pulmonary angiotensin-converting enzyme and angiotensin-converting enzyme 2 activity in acute respiratory distress syndrome

    NARCIS (Netherlands)

    Wosten-van Asperen, Roelie M.; Bos, Albert; Bem, Reinout A.; Dierdorp, Barbara S.; Dekker, Tamara; van Goor, Harry; Kamilic, Jelena; van der Loos, Chris M.; van den Berg, Elske; Bruijn, Martijn; van Woensel, Job B.; Lutter, Rene

    2013-01-01

    Objective: Angiotensin-converting enzyme and its effector peptide angiotensin II have been implicated in the pathogenesis of acute respiratory distress syndrome. Recently, angiotensin-converting enzyme 2 was identified as the counter-regulatory enzyme of angiotensin-converting enzyme that converts a

  19. Efficient Wide Range Converters (EWiRaC): A new family of high efficient AC-DC Converters

    DEFF Research Database (Denmark)

    Petersen, Lars; Andersen, Michael Andreas E.

    2006-01-01

    The performance in terms of efficiency of the existing power supplies used for PFC is very dependent on the input voltage range. The boost converter is the most commonly used PFC converter because of its simplicity and high efficiency. But, the boost converter as well as other known converters...... the converter topology according to the input voltage. This new converter type has been named: efficient wide range converter (EWiRaC). The performance of the EWiRaC is experimental verified in a universal input range (90-270VAC) application with an output voltage of 185VDC capable of 500W output power. The EWi...

  20. Analog-digital converters for industrial applications including an introduction to digital-analog converters

    CERN Document Server

    Ohnhäuser, Frank

    2015-01-01

    This book offers students and those new to the topic of analog-to-digital converters (ADCs) a broad introduction, before going into details of the state-of-the-art design techniques for SAR and DS converters, including the latest research topics, which are valuable for IC design engineers as well as users of ADCs in applications. The book then addresses important topics, such as correct connectivity of ADCs in an application, the verification, characterization and testing of ADCs that ensure high-quality end products. Analog-to-digital converters are the central element in any data processing system and regulation loops such as modems or electrical motor drives. They significantly affect the performance and resolution of a system or end product. System development engineers need to be familiar with the performance parameters of the converters and understand the advantages and disadvantages of the various architectures. Integrated circuit development engineers have to overcome the problem of achieving high per...

  1. TiConverter: A training image converting tool for multiple-point geostatistics

    Science.gov (United States)

    Fadlelmula F., Mohamed M.; Killough, John; Fraim, Michael

    2016-11-01

    TiConverter is a tool developed to ease the application of multiple-point geostatistics whether by the open source Stanford Geostatistical Modeling Software (SGeMS) or other available commercial software. TiConverter has a user-friendly interface and it allows the conversion of 2D training images into numerical representations in four different file formats without the need for additional code writing. These are the ASCII (.txt), the geostatistical software library (GSLIB) (.txt), the Isatis (.dat), and the VTK formats. It performs the conversion based on the RGB color system. In addition, TiConverter offers several useful tools including image resizing, smoothing, and segmenting tools. The purpose of this study is to introduce the TiConverter, and to demonstrate its application and advantages with several examples from the literature.

  2. Radiation effects in power converters: Design of a radiation hardened integrated switching DC/DC converter

    Science.gov (United States)

    Adell, Philippe

    When electronic devices are used in space and military systems, they may be exposed to various types of radiation, including photons, electrons, protons, neutrons, and heavy ions. The effects of radiation on the semiconductor devices within the systems range from gradual degradation to catastrophic failure. In order to design and produce reliable systems for space or military applications, it is necessary to understand the device-level effects of radiation and develop appropriate strategies for reducing system susceptibility. This research focuses on understanding radiation effects in power converters for space and military applications. We show that power converters are very sensitive to radiation (total-dose, single event effects and displacement damage) and that their radiation response is dependent on input bias conditions and load conditions. We compared the radiation hardness of various power converter topologies using experiments and simulations. Evaluation of these designs under different modes of operation is demonstrated to be critical for determining radiation hardness. We emphasize the correlation between radiation effects and the role of the dynamic response of these topologies. For instance, total dose exposure has been found to degrade loop gain and affect regulation in some converters. We propose several radiation-hardening solutions to improve the radiation response of these designs. For instance, we demonstrate the design of a digitally controlled boost converter suitable for space applications based on an SRAM FPGA. A design hardening solution has been developed and successfully applied through VHDL simulations and experiments to assure the continuous operation of the converter in the presence of SEES (more precisely SEFIs). This research led to the design of a digitally controlled radiation hardened integrated switching buck converter. The proposed design is suitable for micro-satellite applications and is based on a high-voltage/CMOS process

  3. Parametric study of minimum converter loss in an energy-storage dc-to-dc converter

    Science.gov (United States)

    Wong, R. C.; Owen, H. A., Jr.; Wilson, T. G.

    1982-01-01

    Through a combination of analytical and numerical minimization procedures, a converter design that results in the minimum total converter loss (including core loss, winding loss, capacitor and energy-storage-reactor loss, and various losses in the semiconductor switches) is obtained. Because the initial phase involves analytical minimization, the computation time required by the subsequent phase of numerical minimization is considerably reduced in this combination approach. The effects of various loss parameters on the optimum values of the design variables are also examined.

  4. MAGIC: Model and Graphic Information Converter

    Science.gov (United States)

    Herbert, W. C.

    2009-01-01

    MAGIC is a software tool capable of converting highly detailed 3D models from an open, standard format, VRML 2.0/97, into the proprietary DTS file format used by the Torque Game Engine from GarageGames. MAGIC is used to convert 3D simulations from authoritative sources into the data needed to run the simulations in NASA's Distributed Observer Network. The Distributed Observer Network (DON) is a simulation presentation tool built by NASA to facilitate the simulation sharing requirements of the Data Presentation and Visualization effort within the Constellation Program. DON is built on top of the Torque Game Engine (TGE) and has chosen TGE's Dynamix Three Space (DTS) file format to represent 3D objects within simulations.

  5. Faults and Diagnosis Systems in Power Converters

    DEFF Research Database (Denmark)

    Lee, Kyo-Beum; Choi, Uimin

    2014-01-01

    efforts have been put into making these systems better in terms of reliability in order to achieve high power source availability, reduce the cost of energy and also increase the reliability of overall systems. Among the components used in power converters, a power device and a capacitor fault occurs most......A power converter is needed in almost all kinds of renewable energy systems and drive systems. It is used both for controlling the renewable source and for interfacing with the load, which can be grid-connected or working in standalone mode. Further, it drives the motors efficiently. Increasing...... frequently. Therefore, it is important to monitor the power device and capacitor fault to increase the reliability of power electronics. In this chapter, the diagnosis methods for power device fault will be discussed by dividing into open- and short-circuit faults. Then, the condition monitoring methods...

  6. Strained quantum well photovoltaic energy converter

    Science.gov (United States)

    Freundlich, Alexandre (Inventor); Renaud, Philippe (Inventor); Vilela, Mauro Francisco (Inventor); Bensaoula, Abdelhak (Inventor)

    1998-01-01

    An indium phosphide photovoltaic cell is provided where one or more quantum wells are introduced between the conventional p-conductivity and n-conductivity indium phosphide layer. The approach allows the cell to convert the light over a wider range of wavelengths than a conventional single junction cell and in particular convert efficiently transparency losses of the indium phosphide conventional cell. The approach hence may be used to increase the cell current output. A method of fabrication of photovoltaic devices is provided where ternary InAsP and InGaAs alloys are used as well material in the quantum well region and results in an increase of the cell current output.

  7. Component technology for Stirling power converters

    Science.gov (United States)

    Thieme, Lanny G.

    NASA Lewis Research Center has organized a component technology program as part of the efforts to develop Stirling converter technology for space power applications. The Stirling Space Power Program is part of the NASA High Capacity Power Project of the Civil Space Technology Initiative (CSTI). NASA Lewis is also providing technical management for the DOE/Sandia program to develop Stirling converters for solar terrestrial power producing electricity for the utility grid. The primary contractors for the space power and solar terrestrial programs develop component technologies directly related to their goals. This Lewis component technology effort, while coordinated with the main programs, aims at longer term issues, advanced technologies, and independent assessments. An overview of work on linear alternators, engine/alternator/load interactions and controls, heat exchangers, materials, life and reliability, and bearings is presented.

  8. A Variational Inequality from Pricing Convertible Bond

    Directory of Open Access Journals (Sweden)

    Yan Huiwen

    2011-01-01

    Full Text Available The model of pricing American-style convertible bond is formulated as a zero-sum Dynkin game, which can be transformed into a parabolic variational inequality (PVI. The fundamental variable in this model is the stock price of the firm which issued the bond, and the differential operator in PVI is linear. The optimal call and conversion strategies correspond to the free boundaries of PVI. Some properties of the free boundaries are studied in this paper. We show that the bondholder should convert the bond if and only if the price of the stock is equal to a fixed value, and the firm should call the bond back if and only if the price is equal to a strictly decreasing function of time. Moreover, we prove that the free boundaries are smooth and bounded. Eventually we give some numerical results.

  9. MOCCASIN: converting MATLAB ODE models to SBML.

    Science.gov (United States)

    Gómez, Harold F; Hucka, Michael; Keating, Sarah M; Nudelman, German; Iber, Dagmar; Sealfon, Stuart C

    2016-06-15

    MATLAB is popular in biological research for creating and simulating models that use ordinary differential equations (ODEs). However, sharing or using these models outside of MATLAB is often problematic. A community standard such as Systems Biology Markup Language (SBML) can serve as a neutral exchange format, but translating models from MATLAB to SBML can be challenging-especially for legacy models not written with translation in mind. We developed MOCCASIN (Model ODE Converter for Creating Automated SBML INteroperability) to help. MOCCASIN can convert ODE-based MATLAB models of biochemical reaction networks into the SBML format. MOCCASIN is available under the terms of the LGPL 2.1 license (http://www.gnu.org/licenses/lgpl-2.1.html). Source code, binaries and test cases can be freely obtained from https://github.com/sbmlteam/moccasin : mhucka@caltech.edu More information is available at https://github.com/sbmlteam/moccasin. © The Author 2016. Published by Oxford University Press.

  10. The Combined Action of ENHANCED DISEASE SUSCEPTIBILITY1, PHYTOALEXIN DEFICIENT4, and SENESCENCE-ASSOCIATED101 Promotes Salicylic Acid-Mediated Defenses to Limit Fusarium graminearum Infection in Arabidopsis thaliana.

    Science.gov (United States)

    Makandar, Ragiba; Nalam, Vamsi J; Chowdhury, Zulkarnain; Sarowar, Sujon; Klossner, Guy; Lee, Hyeonju; Burdan, Dehlia; Trick, Harold N; Gobbato, Enrico; Parker, Jane E; Shah, Jyoti

    2015-08-01

    Fusarium graminearum causes Fusarium head blight (FHB) disease in wheat and other cereals. F. graminearum also causes disease in Arabidopsis thaliana. In both Arabidopsis and wheat, F. graminearum infection is limited by salicylic acid (SA) signaling. Here, we show that, in Arabidopsis, the defense regulator EDS1 (ENHANCED DISEASE SUSCEPTIBILITY1) and its interacting partners, PAD4 (PHYTOALEXIN-DEFICIENT4) and SAG101 (SENESCENCE-ASSOCIATED GENE101), promote SA accumulation to curtail F. graminearum infection. Characterization of plants expressing the PAD4 noninteracting eds1(L262P) indicated that interaction between EDS1 and PAD4 is critical for limiting F. graminearum infection. A conserved serine in the predicted acyl hydrolase catalytic triad of PAD4, which is not required for defense against bacterial and oomycete pathogens, is necessary for limiting F. graminearum infection. These results suggest a molecular configuration of PAD4 in Arabidopsis defense against F. graminearum that is different from its defense contribution against other pathogens. We further show that constitutive expression of Arabidopsis PAD4 can enhance FHB resistance in Arabidopsis and wheat. Taken together with previous studies of wheat and Arabidopsis expressing salicylate hydroxylase or the SA-response regulator NPR1 (NON-EXPRESSER OF PR GENES1), our results show that exploring fundamental processes in a model plant provides important leads to manipulating crops for improved disease resistance.

  11. Multiport Resonant DC-DC Converter

    OpenAIRE

    Tran, Yan-Kim; Dujic, Drazen; Barrade, Philippe

    2015-01-01

    his paper presents a multiport galvanically isolated LLC resonant DC-DC converter suitable for DC applications. A three-port structure is analyzed, with full bidirectional power flow capabilities, simple control and behavior similar to that expected from a DC transformer. Each port is equipped with half-bridge modules accompanied with tuned resonant tank, partly realized with elements of a multi- winding high frequency transformer. With some restrictions that are explained in the paper, each ...

  12. Converting Student Support Services to Online Delivery

    OpenAIRE

    David E. Brigham

    2001-01-01

    This case study describes how Regents College (soon to be Excelsior College), an accredited, private, distance education institution with administrative offices in Albany, New York addressed the structural, management, and resource issues that came into play when converting distance education programs from print-based and telephone delivery to online delivery. The study uses a systems framework to describe and analyze the circumstances and issues surrounding the creation of six student suppor...

  13. Reversible thyristor converters of brushless synchronous compensators

    Directory of Open Access Journals (Sweden)

    А.М.Galynovskiy

    2013-12-01

    Full Text Available Behavior of models of three-phase-to-single-phase rotary reversible thyristor converters of brushless synchronous compensators in a circuit simulation system is analyzed. It is shown that combined control mode of opposite-connected thyristors may result in the exciter armature winding short circuits both at the thyristor feed-forward and lagging current delay angles. It must be taken into consideration when developing brushless compensator excitation systems.

  14. (Convertible) Undeniable Signatures Without Random Oracles

    Science.gov (United States)

    Yuen, Tsz Hon; Au, Man Ho; Liu, Joseph K.; Susilo, Willy

    We propose a convertible undeniable signature scheme without random oracles. Our construction is based on Waters' and Kurosawa and Heng's schemes that were proposed in Eurocrypt 2005. The security of our scheme is based on the CDH and the decision linear assumption. Comparing only the part of undeniable signatures, our scheme uses more standard assumptions than the existing undeniable signatures without random oracles due to Laguillamie and Vergnaud.

  15. Fracture imaging with converted elastic waves

    Energy Technology Data Exchange (ETDEWEB)

    Nihei, K.T.; Nakagawa, S.; Myer, L.R.

    2001-05-29

    This paper examines the seismic signatures of discrete, finite-length fractures, and outlines an approach for elastic, prestack reverse-time imaging of discrete fractures. The results of this study highlight the importance of incorporating fracture-generated P-S converted waves into the imaging method, and presents an alternate imaging condition that can be used in elastic reverse-time imaging when a direct wave is recorded (e.g., for crosswell and VSP acquisition geometries).

  16. Spectral converters and luminescent solar concentrators

    CERN Document Server

    Scudo, Petra F; Fusco, Roberto

    2009-01-01

    In this paper we present a comprehensive theoretical description of molecular spectral converters in the specific context of Luminescent Solar Concentrators (LSCs). The theoretical model is an extension to a three-level system interacting with a solar radiation bath of the standard quantum theory of atomic radiative processes. We derive the equilibrium equations of the conversion process and provide specific examples of application of this principle to the development of solar concentration devices.

  17. The CERN Control Protocol for power converters

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, I.; Benincasa, G.; Berrig, O.; Brun, R.; Burla, P.; Coudert, G.; Pett, J.G.; Pittin, R.; Royer, J.P.; Trofimov, N. (CERN, Geneva (Switzerland))

    1993-08-01

    The Control Protocols provide, for a class of similar devices, a unique and standard access procedure from the control system. Behavioral models have been proposed for the different kinds of Power Converters and the corresponding functionalities, with their parameters, variables and attributes have been identified. The resulting data structures have been presented using the ISO ASN.1 metalanguage, that permits universal representation independent of any computer environment. Implementations in the UNIX-based CERN accelerator control systems are under development.

  18. Study on a Novel High-Efficiency Bridgeless PFC Converter

    Directory of Open Access Journals (Sweden)

    Cao Taiqiang

    2014-01-01

    Full Text Available In order to implement a high-efficiency bridgeless power factor correction converter, a new topology and operation principles of continuous conduction mode (CCM and DC steady-state character of the converter are analyzed, which show that the converter not only has bipolar-gain characteristic but also has the same characteristic as the traditional Boost converter, while the voltage transfer ratio is not related with the resonant branch parameters and switching frequency. Based on the above topology, a novel bridgeless Bipolar-Gain Pseudo-Boost PFC converter is proposed. With this converter, the diode rectifier bridge of traditional AC-DC converter is eliminated, and zero-current switching of fast recovery diode is achieved. Thus, the efficiency is improved. Next, we also propose the one-cycle control policy of this converter. Finally, experiments are provided to verify the accuracy and feasibility of the proposed converter.

  19. Optimizing Design of UHVDC Converter Stations

    Institute of Scientific and Technical Information of China (English)

    MA Weimin; NIE Dingzhen; CAO Yanming

    2012-01-01

    Based on the consultation and study for Xiangjiaba-Shanghai ±800 kV UHVDC(ultra high voltage direct current) project, this paper presents an optimal design for key technique solutions. In this paper, the DC system electrical scheme design, the DC filter design, the DC harmonic component suppression, the over voltage and insulation coordination, the requirements for converter station equipment, the main equipment technical parameters of equipment (including thyristor valve, converter transformer, smoothing reactor, DC breaker), the configuration of measuring device and DC control protection system, and the de-icing operation design are investigated. According to the UHVDC technology researched conclusions and the development of the project construction, the UHVDC system design for converter stations becomes an optimal combination. The optimized design solves numbers of technical problems of the world's first UHVDC project, and it is applied to the project's construction. Under the actual operating condition, the optimized design is proved to be correct and superior. These optimal design conclusions are impartment for developing UHVDC technique and equipment, and provide reference for future UHVDC projects.

  20. Converter fed sub sea motor drives

    Energy Technology Data Exchange (ETDEWEB)

    Raad, R.O.

    1995-09-01

    Minor offshore gas and oil resources located 20-50 km from existing installations may often be commercially exploited only by use of complete sub sea solutions. This thesis deals with analyses of a sub sea adjustable speed electric motor which is fed by a frequency converter via a long cable (up to 50 km) between the converter and the motor. The author develops a general model for analysing such motor drive systems with the objective of verifying the feasibility of specific applications and of specifying the requirements on the system components. The simulation model is used to identify the critical frequency ranges in which the converter must not generate significant harmonics, to verify the start-up strategy chosen, and to verify the stability with potential disturbances applied to the system. Simulation models are developed for both transient and steady state analyses. They are accurate up to 5 kHz and can incorporate the frequency dependency of the motor and cable parameters. Ideal thyristors and diodes are used. The models are implemented in existing simulation tools. Most of the results relate to a base case with a 670 kW squirrel cage motor fed from a 30 km long cable, but cases with 3 MW rating or with 50 km cable have also been analyzed and found to be feasible. Each specific application must be separately studied. Results of simulation calculations are presented and conclusions given. 53 refs., 124 figs., 23 tabs.

  1. Accelerated commutation for passive clamp isolated boost converters

    OpenAIRE

    2002-01-01

    An efficient and cost effective bidirectional DC/DC converter reduces switch voltage stress via accelerated commutation allowing use of a low-cost passive clamp circuit in boost mode. The converter includes a primary circuit, transformer and secondary circuit. The primary circuit takes the form of a “full bridge converter,” a “push-pull converter,” or an “L-type converter.”. The primary circuit may include a dissipator such as a snubber circuit or small buck converter. A secondary side of the...

  2. One-Quadrant Switched-Mode Power Converters

    CERN Document Server

    Petrocelli, R

    2015-01-01

    This article presents the main topics related to one-quadrant power convert- ers. The basic topologies are analysed and a simple methodology to obtain the steady-state output–input voltage ratio is set out. A short discussion of dif- ferent methods to control one-quadrant power converters is presented. Some of the reported derived topologies of one-quadrant power converters are also considered. Some topics related to one-quadrant power converters such as syn- chronous rectification, hard and soft commutation, and interleaved converters are discussed. Finally, a brief introduction to resonant converters is given.

  3. High Current, Low Voltage Power Converter [20kA, 6V] LHC Converter Prototype

    CERN Document Server

    Jørgensen, H E; Dupaquier, A; Fernqvist, G

    1998-01-01

    The superconducting LHC accelerator requires high currents (~12.5kA) and relatively low voltages (~10 V) for its magnets. The need to install the power converters underground is the driving force for reduced volume and high efficiency. Moreover, the LHC machine will require a very high level of performance from the power converters, particularly in terms of DC stability, dynamic response and also in matters of EMC. To meet these requirements soft-switching techniques will be used. This paper describes the development of a [20kA,6V] power converter intended as a stable high-current source for D CCT calibration and an evaluation prototype for the future LHC converters. The converter is made with a modular concept with five current sources [4kA,6V] in parallel. The 4kA sources are built as plu g-in modules: a diode rectifier on the AC mains with a damped L-C passive filter, a Zero Voltage Switching inverter working at 20 kHz and an output stage (high frequency transformers, Schottky rectifi ers and output filter...

  4. High power density dc/dc converter: Selection of converter topology

    Science.gov (United States)

    Divan, Deepakraj M.

    1990-01-01

    The work involved in the identification and selection of a suitable converter topology is described. Three new dc/dc converter topologies are proposed: Phase-Shifted Single Active Bridge DC/DC Converter; Single Phase Dual Active Bridges DC/DC Converter; and Three Phase Dual Active Bridges DC/DC Converter (Topology C). The salient features of these topologies are: (1) All are minimal in structure, i.e., each consists of an input and output bridge, input and output filter and a transformer, all components essential for a high power dc/dc conversion process; (2) All devices of both the bridges can operate under near zero-voltage conditions, making possible a reduction of device switching losses and hence, an increase in switching frequency; (3) All circuits operate at a constant frequency, thus simplifying the task of the magnetic and filter elements; (4) Since, the leakage inductance of the transformer is used as the main current transfer element, problems associated with the diode reverse recovery are eliminated. Also, this mode of operation allows easy paralleling of multiple modules for extending the power capacity of the system; (5) All circuits are least sensitive to parasitic impedances, infact the parasitics are efficently utilized; and (6) The soft switching transitions, result in low electromagnetic interference. A detailed analysis of each topology was carried out. Based on the analysis, the various device and component ratings for each topology operating at an optimum point, and under the given specifications, are tabulated and discussed.

  5. Comparison between the Performance of Basic SEPIC Converter and modified SEPIC Converter with PI Controller

    Directory of Open Access Journals (Sweden)

    Satyendra Kumar Gupta

    2014-08-01

    Full Text Available There are multiple solutions in which line current is sinusoidal. In addition, in the recent years, a great number of circuits have been proposed with non sinusoidal line current. In this paper, a review of the most interesting solutions for single phase and low power applications is carried out. They are classified attending to the line current waveform, energy processing, number of switches, control loops, etc. The major advantages and disadvantages are highlighted and the field of application is found. The paper presents performance analysis of modified SEPIC dc-dc converter with low input voltage and wide output voltage range. The operational analysis and the design is done for the 380W power output of the modified converter. The simulation results of modified SEPIC converter are obtained with PI controller for the output voltage. The results obtained with the modified converter are compared with the basic SEPIC converter topology for the rise time, peak time, settling time and steady state error of the output response for open loop. Voltage tracking curve is also shown for wide output voltage range.

  6. An Efficient DC- DC Converter with Bidirectional Power Flow

    Directory of Open Access Journals (Sweden)

    N.RAJARAJESWARI

    2008-07-01

    Full Text Available This paper introduces a Bi-directional DC-DC converter with adaptive fuzzy logic controller. Bidirectional power flow is obtained by same power components and provides a simple, efficient, and galvanically isolated converter. In the presence of DC mains the converter operates as buck converter and charges the battery. When the DC mains fails, the converter operates as boost converter and the down stream converter is fed by the battery. The power switches are controlled by Pulse Width Modulation technique and the pulses are generated by the application of fuzzy logic with an adoption algorithm. The proposed converter is simulated using MATLAB and laboratory prototype was developed to validate the simulation results.

  7. A Three-Phase Interleaved Floating Output Boost Converter

    Directory of Open Access Journals (Sweden)

    Ajmal Farooq

    2015-01-01

    Full Text Available High step-up dc-dc converter is an essential part in several renewable energy systems. In this paper, a new topology of step-up dc-dc converter based on interleaved structure is proposed. The proposed converter uses three energy storing capacitors to achieve a high voltage gain. Besides the high voltage gain feature, the proposed converter also reduces the voltage stress across the semiconductor switches. This helps in using low rating switching devices which can reduce the overall size and cost of the converter. The operating principle of the proposed converter is discussed in detail and its principle waveforms are analyzed. An experiment is carried out on a 20 V input, 130 V output, and 21 W power prototype of the proposed converter in the laboratory to verify the performance of the proposed converter. An efficiency of 91.3% is achieved at the rated load.

  8. A resonant dc-dc power converter assembly

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a resonant DC-DC power converter assembly comprising a first resonant DC-DC power converter and a second resonant DC-DC power converter having identical circuit topologies. A first inductor of the first resonant DC-DC power converter and a second inductor...... of the second resonant DC-DC power converter are configured for magnetically coupling the first and second resonant DC-DC power converters to each other to forcing substantially 180 degrees phase shift, or forcing substantially 0 degree phase shift, between corresponding resonant voltage waveforms of the first...... and second resonant DC-DC power converters. The first and second inductors are corresponding components of the first and second resonant DC-DC power converters....

  9. Optical analog-to-digital converter

    Science.gov (United States)

    Evanchuk, Vincent L. (Inventor)

    1984-01-01

    A method and apparatus for converting the intensity of an unknown optical signal (B) into an electrical signal in digital form utilizes two elongated optical attenuators (11, 13), one for the unknown optical signal from a source (10) and one for a known optical signal (A) from a variable source (12), a plurality of photodetectors (e.g., 17, 18) along each attenuator for detecting the intensity of the optical signals, and a plurality of comparators (e.g., 21) connected to the photodetectors in pairs to determine at what points being compared the attenuated known signal equals the attenuated unknown signal. The intensity of the unknown relative to the known is thus determined by the output of a particular comparator. That output is automatically encoded to a relative intensity value in digital form through a balancing feedback control (24) and encoder (23). The digital value may be converted to analog form in a D-to-A converter (27) and used to vary the source of the known signal so that the attenuated intensity of the known signal at a predetermined point (comparator 16) equals the attenuated intensity of the unknown signal at the predetermined point of comparison. If the known signal is then equal to the unknown, there is verification of the analog-to-digital conversion being complete. Otherwise the output of the comparator indicating equality at some other point along the attenuators will provide an output which is encoded and added, through an accumulator comprised of a register (25) and an adder (26), to a previous relative intensity value thereby to further vary the intensity of the known signal source. The steps are repeated until full conversion is verified.

  10. Power converters for medium voltage networks

    CERN Document Server

    Islam, Md Rabiul; Zhu, Jianguo

    2014-01-01

    This book examines a number of topics, mainly in connection with advances in semiconductor devices and magnetic materials and developments in medium and large-scale renewable power plant technologies, grid integration techniques and new converter topologies, including advanced digital control systems for medium-voltage networks. The book's individual chapters provide an extensive compilation of fundamental theories and in-depth information on current research and development trends, while also exploring new approaches to overcoming some critical limitations of conventional grid integration te

  11. Waste Plastic Converting into Hydrocarbon Fuel Materials

    Energy Technology Data Exchange (ETDEWEB)

    Sarker, Moinuddin; Mamunor Rashid, Mohammad; Molla, Mohammad

    2010-09-15

    The increased demand and high prices for energy sources are driving efforts to convert organic compounds into useful hydrocarbon fuels. Although much of this work has focused on biomass, there are strong benefits to deriving fuels from waste plastic material. Natural State Research Inc. (NSR) has invented a simple and economically viable process to decompose the hydrocarbon polymers of waste plastic into the shorter chain hydrocarbon of liquid fuel (patent pending). The method and principle of the production / process will be discussed. Initial tests with several widely used polymers indicate a high potential for commercialization.

  12. Dead time optimization method for power converter

    Science.gov (United States)

    Deselaers, C.; Bergmann, U.; Gronwald, F.

    2013-07-01

    This paper introduces a method for dead time optimization in variable speed motor drive systems. The aim of this method is to reduce the conduction time of the freewheeling diode to a minimum without generation of cross conduction. This results in lower losses, improved EMC, and less overshooting of the phase voltage. The principle of the method is to detect beginning cross currents without adding additional components in the half bridge like resistors or inductances. Only the wave shape of the phase voltage needs to be monitored during switching. This is illustrated by an application of the method to a real power converter.

  13. Converting Student Support Services to Online Delivery

    Directory of Open Access Journals (Sweden)

    David E. Brigham

    2001-01-01

    Full Text Available This case study describes how Regents College (soon to be Excelsior College, an accredited, private, distance education institution with administrative offices in Albany, New York addressed the structural, management, and resource issues that came into play when converting distance education programs from print-based and telephone delivery to online delivery. The study uses a systems framework to describe and analyze the circumstances and issues surrounding the creation of six student support services: electronic advising, an electronic peer network, an online database of distance courses, an online bookstore, a virtual library, and an alumni services website.

  14. Converting VSAM in COBOL to embedded SQL

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Hai; Wang, Yamin; Tsai, Wei-Tek [Univ. of Minnesota, Minneapolis, MN (United States)

    1996-12-31

    VSAM databases we widely used on IBM mainframe systems. As new technology, such as relational database and client-server computing, becomes popular, there is a need to reengineer the VSAM databases to relational databases. This paper addresses the issues on converting COBOL programs that access VSAM database to COBOL programs that access relational databases with embedded SQL. It proposed a semi-automatic approach to the conversion of VSAM data sets to SQL tables and VSAM operations in COBOL program to embedded SQL queries. The proposed approach has been experimented on several industrial COBOL programs and a tool implementing the approach is under development.

  15. Monolithically integrated optoelectronic down-converter (MIOD)

    Science.gov (United States)

    Portnoi, Efrim L.; Venus, G. B.; Khazan, A. A.; Gorfinkel, Vera B.; Kompa, Guenter; Avrutin, Evgenii A.; Thayne, Iain G.; Barrow, David A.; Marsh, John H.

    1995-06-01

    Optoelectronic down-conversion of very high-frequency amplitude-modulated signals using a semiconductor laser simultaneously as a local oscillator and a mixer is proposed. Three possible constructions of a monolithically integrated down-converter are considered theoretically: a four-terminal semiconductor laser with dual pumping current/modal gain control, and both a passively mode-locked and a passively Q-switched semiconductor laser monolithically integrated with an electroabsorption or pumping current modulator. Experimental verification of the feasibility of the concept of down conversion in a laser diode is presented.

  16. Design, modeling and testing of data converters

    CERN Document Server

    Kiaei, Sayfe; Xu, Fang

    2014-01-01

    This book presents the a scientific discussion of the state-of-the-art techniques and designs for modeling, testing and for the performance analysis of data converters. The focus is put on sustainable data conversion. Sustainability has become a public issue that industries and users can not ignore. Devising environmentally friendly solutions for data conversion designing, modeling and testing is nowadays a requirement that researchers and practitioners must consider in their activities. This book presents the outcome of the IWADC workshop 2011, held in Orvieto, Italy.

  17. EMI filter techniques in power electronic converters

    Directory of Open Access Journals (Sweden)

    Fredy Edimer Hoyos Velasco

    2012-04-01

    Full Text Available This paper presents the results of EMI reduction techniques applied to power electronic converters. The techniques applied included shielding control and power signals, separating power system references regarding reference for instrumentation and measurement signals, implementing analog filters and configuring an appropriate switch trigger system for electronic power to decrease shifting EMI emissions to the maximum. This paper presents the results before and after applying the techniques to reduce interference. The results were also veryfied by using two real time control strategies rapid control prototyping (RCP.

  18. Development of a test platform for controlling parallel converters

    DEFF Research Database (Denmark)

    Bede, Lorand; Kopacz, Csaba; Kerekes, Tamas

    2014-01-01

    a proper interleaving angle between the converters the current ripple can be reduced considerably. In order to be able to investigate the performance of these converters a safe and cheap platform is essential. The development of a test platform for such an application is challenging, since a proper...... synchronization has to be established between the converters. In this paper a universal platform is presented, which allows to parallel n converters with arbitrary interleaving angle between each other....

  19. A New Modular Multilevel Converter with Integrated Energy Storage

    DEFF Research Database (Denmark)

    Trintis, Ionut; Munk-Nielsen, Stig; Teodorescu, Remus

    2011-01-01

    This paper introduces a new modular converter with integrated energy storage based on the cascaded half-bridge modular multilevel converter with common DC bus. It represents a complete modular solution with power electronics and energy storage building blocks, for medium and high voltage...... in the future HVDC meshed grids. Its functionality and flexibility makes the converter independent on the energy storage unit characteristic. The converter concept with its basic functions and control schemes are described and evaluated in this paper....

  20. Simulation of New Switched Capacitance Power Converter for Srm

    Directory of Open Access Journals (Sweden)

    S. M. Mohamed Saleem

    2014-06-01

    Full Text Available In this paper, design and simulation of switched capacitance power converter are proposed for 6/4 switched reluctance motor (SRM drive. The operating principle and design consideration of the proposed converter is explained. The proposed converter performance is better in reduction of torque ripple and constant speed can be achieved quickly with reduced power loss when compared with asymmetric converter. The proposed system is simulated by using MATLAB Simulink and their results are clearly presented.

  1. Multi Port Single Stage Power Electronics Converter and Wind PFC Converter for DC Micro Grid Applications

    Directory of Open Access Journals (Sweden)

    M. Hemachandran

    2014-08-01

    Full Text Available In this study multi port AC/DC-DC single stage power electronics converter proposed for grid power supply. The topology includes reduced number of active element and passive element. Passive element is used to provide to achieve improved voltage gain and to reduce the voltage stress of input side switches. The active-clamp circuits are used to recycle the energy stored in the leakage inductors and to improve the system performances. Here two input port (wind and battery unit and output port connected to dc grid, battery act as charge unit and source. Efficient wind power conversion is achieved by PFC boost dc-dc converter. Controlled and high step up voltage is supplied to multi-port converter from wind source.

  2. Fuzzy control of power converters based on quasilinear modelling

    Science.gov (United States)

    Li, C. K.; Lee, W. L.; Chou, Y. W.

    1995-03-01

    Unlike feedback control by the fuzzy PID method, a new fuzzy control algorithm based on quasilinear modelling of the DC-DC converter is proposed. Investigation is carried out using a buck-boost converter. Simulation results demonstrated that the converter can be regulated with improved performance even when subjected to input disturbance and load variation.

  3. Two phase interleaved buck converter for driving high power LEDs

    DEFF Research Database (Denmark)

    Beczkowski, Szymon; Munk-Nielsen, Stig

    2011-01-01

    increases luminous efficacy of LED compared to PWM dimmed system. Because of the low dynamic resistance of LEDs the duty cycle of the converter does not change greatly with controlled current. By setting the input voltage of the buck converter to around twice the voltage of diode strings, converter can...

  4. Convertible Arbitrage Price Pressure and Short-Sale Constraints

    NARCIS (Netherlands)

    de Jong, Abe; Dutordoir, Marie; van Genuchten, Nathalie; Verwijmeren, Patrick

    2012-01-01

    Using a sample of 4,148 convertibles issued over 1990-2009 by companies listed in 35 countries, the authors exploited worldwide differences in short-sale constraints to examine whether short selling by convertible arbitrageurs creates downward pressure on convertible issuers' stock prices. They foun

  5. Isolated Boost Converter with Bidirectional Operation for Supercapacitor Applications

    DEFF Research Database (Denmark)

    Hernandez Botella, Juan Carlos; Mira Albert, Maria del Carmen; Sen, Gökhan

    2013-01-01

    This paper presents an isolated bidirectional dc/dc converter based on primary parallel isolated boost converter (PPIBC). This topology is an efficient solution in low voltage high power applications due to its ability to handle high currents in the low voltage side. In this paper, the converter ...

  6. Novel screening techniques for wind turbine power converters

    DEFF Research Database (Denmark)

    Jørgensen, Asger Bjørn; Sønderskov, Simon Dyhr; Christensen, Nicklas;

    2016-01-01

    Power converters represent one of the highest failure rates in the wind turbine. Therefore converter manufacturers perform burn-in tests to prevent shipping of faulty converters. Recent developments in junction temperature estimation, based on accurate online IGBT collector-emitter voltage...

  7. 7 CFR 12.32 - Converted wetland identification criteria.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 1 2010-01-01 2010-01-01 false Converted wetland identification criteria. 12.32 Section 12.32 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Wetland Conservation § 12.32 Converted wetland identification criteria. (a) Converted...

  8. Phase controlled dc-ac converter with high frequency switching

    Science.gov (United States)

    Harada, Koosuke; Sakamoto, Hiroshi; Shoyama, Masahito

    A sinusoidal dc-ac converter is presented in which a pair of switches is placed on each side of the primary and secondary of the isolation transformer. This converter is controlled by the phase difference between the two pairs of switches. The transformer is miniaturized by making the switching frequency high. This converter is especially suitable for small uninterruptible power supply systems.

  9. Sheppard-Taylor Isolated High Boost DC-DC Converter

    DEFF Research Database (Denmark)

    Chub, Andrii; Siwakoti, Yam Prasad; Vinnikov, Dmitri

    2017-01-01

    This paper presents a new galvanically isolated step-up dc-dc converter intended for low-power but high step-up applications. The proposed converter is capable of regulating output voltage within a wide range of the input voltage or load variations. In contrast to competitors, the converter can b...

  10. Fault isolation in parallel coupled wind turbine converters

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Thøgersen, Paul Bach; Stoustrup, Jakob

    2010-01-01

    Parallel converters in wind turbine give a number advantages, such as fault tolerance due to the redundant converters. However, it might be difficult to isolate gain faults in one of the converters if only a combined power measurement is available. In this paper a scheme using orthogonal power re...

  11. Forback DC-to-DC converter

    Science.gov (United States)

    Lukemire, Alan T.

    1995-05-01

    A pulse-width modulated DC-to-DC power converter including a first inductor, i.e. a transformer or an equivalent fixed inductor equal to the inductance of the secondary winding of the transformer, coupled across a source of DC input voltage via a transistor switch which is rendered alternately conductive (ON) and nonconductive (OFF) in accordance with a signal from a feedback control circuit is described. A first capacitor capacitively couples one side of the first inductor to a second inductor which is connected to a second capacitor which is coupled to the other side of the first inductor. A circuit load shunts the second capacitor. A semiconductor diode is additionally coupled from a common circuit connection between the first capacitor and the second inductor to the other side of the first inductor. A current sense transformer generating a current feedback signal for the switch control circuit is directly coupled in series with the other side of the first inductor so that the first capacitor, the second inductor and the current sense transformer are connected in series through the first inductor. The inductance values of the first and second inductors, moreover, are made identical. Such a converter topology results in a simultaneous voltsecond balance in the first inductance and ampere-second balance in the current sense transformer.

  12. Converting DYNAMO simulations to Powersim Studio simulations

    Energy Technology Data Exchange (ETDEWEB)

    Walker, La Tonya Nicole; Malczynski, Leonard A.

    2014-02-01

    DYNAMO is a computer program for building and running 'continuous' simulation models. It was developed by the Industrial Dynamics Group at the Massachusetts Institute of Technology for simulating dynamic feedback models of business, economic, and social systems. The history of the system dynamics method since 1957 includes many classic models built in DYANMO. It was not until the late 1980s that software was built to take advantage of the rise of personal computers and graphical user interfaces that DYNAMO was supplanted. There is much learning and insight to be gained from examining the DYANMO models and their accompanying research papers. We believe that it is a worthwhile exercise to convert DYNAMO models to more recent software packages. We have made an attempt to make it easier to turn these models into a more current system dynamics software language, Powersim © Studio produced by Powersim AS2 of Bergen, Norway. This guide shows how to convert DYNAMO syntax into Studio syntax.

  13. Angiotensin converting enzyme 2 and atherosclerosis.

    Science.gov (United States)

    Wang, Yutang; Tikellis, Chris; Thomas, Merlin C; Golledge, Jonathan

    2013-01-01

    Angiotensin converting enzyme 2 (ACE2) is a homolog of angiotensin converting enzyme (ACE) which generates angiotensin II from angiotensin I. ACE, its product angiotensin II and the downstream angiotensin type I receptor are important components of the renin-angiotensin system (RAS). Angiotensin II, the most important component of the RAS, promotes the development of atherosclerosis. The identification of ACE2 in 2000 opened a new chapter of research on the regulation of the RAS. ACE2 degrades pro-atherosclerotic angiotensin II and generates anti-atherosclerotic angiotensin 1-7. In this review, we explored the importance of ACE2 in protecting experimental animals from developing atherosclerosis and its involvement in human atherosclerosis. We also examined the published evidence assessing the importance of ACE2 in different cell types relevant to atherosclerosis and putative underlying cellular and molecular mechanisms linking ACE2 with protection from atherosclerosis. ACE2 shifts the balance from angiotensin II to angiotensin 1-7 inhibiting the progression of atherosclerosis in animal models.

  14. A novel converter topology for TEM applications

    Indian Academy of Sciences (India)

    S Kedarnath; Krishna Vasudevan

    2008-10-01

    Time-domain Electro Magnetic (TEM) systems, are used for remote sensing of conductive mineral deposits buried under the surface of the earth. A low frequency trapezoidal current excitation set-up in an exciter coil loop causes a flux that penetrates deep into the earth. When the excitation is cut off sharply, conductive deposits in the earth carrying flux react by causing eddy current flows within them. The flux produced by such eddy currents is picked up by a sensor coil. By comparing the emf induced in the sensor coil with a priori known emf patterns for mineral deposits, the presence of mineral deposits can be ascertained. The voltage, current and energy levels of the TEM system, require special type of excitation technique. Power converters for such non-standard requirements are not reported in the literature, particularly for TEM applications. This paper introduces TEM systems to the reader and presents the requirements for excitation. A converter topology to meet the requirements, it’s analysis, control and performance are presented. Among other alternatives that the authors have attempted, the topology presented features reduced number of passive elements, high voltage gain and low losses. These features enable the sensor head to be operated from the normal low level battery.

  15. Forback DC-to-DC converter

    Science.gov (United States)

    Lukemire, Alan T. (Inventor)

    1993-01-01

    A pulse-width modulated DC-to-DC power converter including a first inductor, i.e. a transformer or an equivalent fixed inductor equal to the inductance of the secondary winding of the transformer, coupled across a source of DC input voltage via a transistor switch which is rendered alternately conductive (ON) and nonconductive (OFF) in accordance with a signal from a feedback control circuit is described. A first capacitor capacitively couples one side of the first inductor to a second inductor which is connected to a second capacitor which is coupled to the other side of the first inductor. A circuit load shunts the second capacitor. A semiconductor diode is additionally coupled from a common circuit connection between the first capacitor and the second inductor to the other side of the first inductor. A current sense transformer generating a current feedback signal for the switch control circuit is directly coupled in series with the other side of the first inductor so that the first capacitor, the second inductor and the current sense transformer are connected in series through the first inductor. The inductance values of the first and second inductors, moreover, are made identical. Such a converter topology results in a simultaneous voltsecond balance in the first inductance and ampere-second balance in the current sense transformer.

  16. Wind Energy Conversion Based on Matrix Converter

    Directory of Open Access Journals (Sweden)

    Mutharasan Anburaj

    2014-07-01

    Full Text Available In recent years renewable sources such as solar, wave and wind are used for the generation of electricity. Wind is one of the major renewable sources. The amount of energy from a Wind Energy Conversion System (WECS depends not only on the wind at the site, but also on the control strategy used for the WECS. In assistance to get the appropriate wind energy from the conversion system, wind turbine generator will be run in variable speed mode. The variable speed capability is achieved through the use of an advanced power electronic converter. Fixed speed wind turbines and induction generators are often used in wind farms. But the limitations of such generators are low efficiency and poor power quality which necessitates the variable speed wind turbine generators such as Doubly Fed Induction Generator (DFIG and Permanent Magnet Synchronous Generator (PMSG. A high-performance configuration can be obtained by using Scherbius drive composed of a DFIG and a converter in combination AC-DC-AC connect between stator & rotor points for providing the required variable speed operation

  17. Serial Pixel Analog-to-Digital Converter

    Energy Technology Data Exchange (ETDEWEB)

    Larson, E D

    2010-02-01

    This method reduces the data path from the counter to the pixel register of the analog-to-digital converter (ADC) from as many as 10 bits to a single bit. The reduction in data path width is accomplished by using a coded serial data stream similar to a pseudo random number (PRN) generator. The resulting encoded pixel data is then decoded into a standard hexadecimal format before storage. The high-speed serial pixel ADC concept is based on the single-slope integrating pixel ADC architecture. Previous work has described a massively parallel pixel readout of a similar architecture. The serial ADC connection is similar to the state-of-the art method with the exception that the pixel ADC register is a shift register and the data path is a single bit. A state-of-the-art individual-pixel ADC uses a single-slope charge integration converter architecture with integral registers and “one-hot” counters. This implies that parallel data bits are routed among the counter and the individual on-chip pixel ADC registers. The data path bit-width to the pixel is therefore equivalent to the pixel ADC bit resolution.

  18. Data Converters Performance at Extreme Temperatures

    Science.gov (United States)

    Rejeshuni, Rarnesham; Kumar, Nikil; Mao, James; Keymeulen, Didier; Zebulum, Ricardo S.; Stoica, Adrian

    2006-01-01

    Space missions often require radiation and extreme-temperature hardened electronics to survive the harsh environments beyond earth's atmosphere. Traditional approaches to preserve electronics incorporate shielding, insulation and redundancy at the expense of power and weight. However, a novel way of bypassing these problems is the concept of evolutionary hardware. A reconfgurable device, consisting of several switches interconnected with analog/digital parts, is controlled by an evolutionary processor (EP). When the EP detects degradation in the circuit it sends signals to reconfgure the switches, thus forming a new circuit with the desired output. This concept has been developed since the mid-90s, but one problem remains - the EP cannot degrade substantially. For this reason, extensive testing at extreme temperatures (-180' to 120(deg)C) has been done on devices found on FPGA boards (taking the role of the EP) such as the Analog to Digital and the Digital to Analog Converter. Analysis of the results has shown that FPGA boards implementing EP with some compensation may be a practical solution to evolving circuits. This paper describes results on the tests of data converters at extreme temperatures.

  19. CCLIBS: The CERN Power Converter Control Libraries

    CERN Document Server

    AUTHOR|(SzGeCERN)404953; Lebioda, Krzysztof Tomasz; Magrans De Abril, Marc; Martino, Michele; Murillo Garcia, Raul; Nicoletti, Achille

    2015-01-01

    Accurate control of power converters is a vital activity in large physics projects. Several different control scenarios may coexist, including regulation of a circuit’s voltage, current, or field strength within a magnet. Depending on the type of facility, a circuit’s reference value may be changed asynchronously or synchronously with other circuits. Synchronous changes may be on demand or under the control of a cyclic timing system. In other cases, the reference may be calculated in real-time by an outer regulation loop of some other quantity, such as the tune of the beam in a synchrotron. The power stage may be unipolar or bipolar in voltage and current. If it is unipolar in current, it may be used with a polarity switch. Depending on the design, the power stage may be controlled by a firing angle or PWM duty-cycle reference, or a voltage or current reference. All these cases are supported by the CERN Converter Control Libraries (CCLIBS). These open-source C libraries include advanced reference generati...

  20. Buck-boost converter feedback controller design via evolutionary search

    Science.gov (United States)

    Sundareswaran, K.; Devi, V.; Nadeem, S. K.; Sreedevi, V. T.; Palani, S.

    2010-11-01

    Buck-boost converters are switched power converters. The model of the converter system varies from the ON state to the OFF state and hence traditional methods of controller design based on approximate transfer function models do not yield good dynamic response at different operating points of the converter system. This article attempts to design a feedback controller for a buck-boost type dc-dc converter using a genetic algorithm. The feedback controller design is perceived as an optimisation problem and a robust controller is estimated through an evolutionary search. Extensive simulation and experimental results provided in the article show the effectiveness of the new approach.

  1. A nanoscale linear-to-linear motion converter of graphene.

    Science.gov (United States)

    Dai, Chunchun; Guo, Zhengrong; Zhang, Hongwei; Chang, Tienchong

    2016-08-14

    Motion conversion plays an irreplaceable role in a variety of machinery. Although many macroscopic motion converters have been widely used, it remains a challenge to convert motion at the nanoscale. Here we propose a nanoscale linear-to-linear motion converter, made of a flake-substrate system of graphene, which can convert the out-of-plane motion of the substrate into the in-plane motion of the flake. The curvature gradient induced van der Waals potential gradient between the flake and the substrate provides the driving force to achieve motion conversion. The proposed motion converter may have general implications for the design of nanomachinery and nanosensors.

  2. Pricing Chinese Convertible Bonds with Dynamic Credit Risk

    Directory of Open Access Journals (Sweden)

    Ping Li

    2014-01-01

    Full Text Available To price convertible bonds more precisely, least squares Monte Carlo (LSM method is used in this paper for its advantage in handling the dependence of derivatives on the path, and dynamic credit risk is used to replace the fixed one to make the value of convertible bonds reflect the real credit risk. In the empirical study, we price convertible bonds based on static credit risk and dynamic credit risk, respectively. Empirical results indicate that the ICBC convertible bond has been overpriced, resulting from the underestimation of credit risk. In addition, when there is an issue of dividend, the conversion price will change in China's convertible bonds, while it does not change in the international convertible bonds. So we also empirically study the difference between the convertible bond's prices by assuming whether the conversion price changes or not.

  3. Converter applications and their influence on large electrical machines

    CERN Document Server

    Drubel, Oliver

    2013-01-01

    Converter driven applications are applied in more and more processes. Almost any installed wind-farm, ship drives, steel mills, several boiler feed water pumps, extruder and many other applications operate much more efficient and economic in case of variable speed solutions. The boundary conditions for a motor or generator will change, if it is supplied by a converter. An electrical machine, which is operated by a converter, can no longer be regarded as an independent component, but is embedded in a system consisting of converter and machine. This book gives an overview of existing converter designs for large electrical machines. Methods for the appropriate calculation of machine phenomena, which are implied by converters are derived in the power range above 500kVA. It is shown how due to the converter inherent higher voltage harmonics and pulse frequencies special phenomena are caused inside the machine which can be the reason for malfunction. It is demonstrated that additional losses create additional tempe...

  4. Three-phase Resonant DC-link Converter

    DEFF Research Database (Denmark)

    Munk-Nielsen, Stig

    no additional power electric components is eliminating the high voltage peaks associated with the resonant circuit. The resonant link voltage peaks are limited below 2.1 times the DC link voltages. A new principle eliminating former resonant converter stability problems are proposed, implemented and tested......The purpose of the project is to develop a three-phase resonant converter suitable for standard speed drives. The motivation for working with resonant converters is found in the problem of the standard converter type used today. In standard converter type Pulse Width Modulated-Voltage Source....... The high speed of the switches cannot be fully utilizied. By using a parallel resonant converter the switching happens at low or zero voltage which reduses switch losses. The dv/dt is controlled by the resonant circuit, and it is therefore reduced significantly. The perspective using a resonant converter...

  5. Affecting Factors and Improving Measures for Converter Gas Recovery

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    To change the undesirable present situation of recovering and using converter gas in steel plants in China,the basic approaches to improving the converter gas recovery rate were analyzed theoretically along with the change curves of the converter gas component content, based on the converter gas recovery system of Baosteel No. 2 steelmaking plant. The effects of converter device, raw material, air imbibed quantity, recovery restricted condition, and intensity of oxygen blowing on the converter gas recovery rate were studied. Among these, the effects of the air imbibed quantity, recovery restricted condition, and intensity of oxygen blowing are remarkable. Comprehensive measures were put forward for improving the converter gas recovery from the point of devices, etc. , and good results were achieved.

  6. Bifurcation behaviours of peak current controlled PFC boost converter

    Institute of Scientific and Technical Information of China (English)

    Ren Hai-Peng; Liu Ding

    2005-01-01

    Bifurcation behaviours of the peak current controlled power-factor-correction (PFC) boost converter, including fast-scale instability and low-frequency bifurcation, are investigated in this paper. Conventionally, the PFC converter is analysed in continuous conduction mode (CCM). This prevents us from recognizing the overall dynamics of the converter. It has been pointed out that the discontinuous conduction mode (DCM) can occur in the PFC boost converter, especially in the light load condition. Therefore, the DCM model is employed to analyse the PFC converter to cover the possible DCM operation. By this way, the low-frequency bifurcation diagram is derived, which makes the route from period-double bifurcation to chaos clear. The bifurcation diagrams versus the load resistance and the output capacitance also indicate the stable operation boundary of the converter, which is useful for converter design.

  7. Will oscillating wave surge converters survive tsunamis?

    Directory of Open Access Journals (Sweden)

    L. O’Brien

    2015-07-01

    Full Text Available With an increasing emphasis on renewable energy resources, wave power technology is becoming one of the realistic solutions. However, the 2011 tsunami in Japan was a harsh reminder of the ferocity of the ocean. It is known that tsunamis are nearly undetectable in the open ocean but as the wave approaches the shore its energy is compressed, creating large destructive waves. The question posed here is whether an oscillating wave surge converter (OWSC could withstand the force of an incoming tsunami. Several tools are used to provide an answer: an analytical 3D model developed within the framework of linear theory, a numerical model based on the non-linear shallow water equations and empirical formulas. Numerical results show that run-up and draw-down can be amplified under some circumstances, leading to an OWSC lying on dry ground!

  8. Generators for gearless wind energy converters

    Energy Technology Data Exchange (ETDEWEB)

    Grauers, A. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering

    1996-12-01

    This paper discusses some design alternatives for directly driven generators, and one specific generator type is investigated for a wide range of rated power. First, the specification for a directly driven generator is presented, then different design alternatives are discussed. A radial-flux permanent magnet generator for frequency converter connection has been chosen for a more detailed investigation. The design, optimization and performance of that generator type are presented. Generators from 30 kW to 3 MW are designed and compared with conventional four-pole generators with gear. It is found that a directly driven generator can be more efficient than a conventional generator and gear and have a rather small diameter and a low active weight. 8 refs, 7 figs, 2 tabs

  9. Mechanical vibration to electrical energy converter

    Science.gov (United States)

    Kellogg, Rick Allen; Brotz, Jay Kristoffer

    2009-03-03

    Electromechanical devices that generate an electrical signal in response to an external source of mechanical vibrations can operate as a sensor of vibrations and as an energy harvester for converting mechanical vibration to electrical energy. The devices incorporate a magnet that is movable through a gap in a ferromagnetic circuit, wherein a coil is wound around a portion of the ferromagnetic circuit. A flexible coupling is used to attach the magnet to a frame for providing alignment of the magnet as it moves or oscillates through the gap in the ferromagnetic circuit. The motion of the magnet can be constrained to occur within a substantially linear range of magnetostatic force that develops due to the motion of the magnet. The devices can have ferromagnetic circuits with multiple arms, an array of magnets having alternating polarity and, encompass micro-electromechanical (MEM) devices.

  10. Modular Power Converters for PV Applications

    Energy Technology Data Exchange (ETDEWEB)

    Ozpineci, Burak [ORNL; Tolbert, Leon M [ORNL

    2012-05-01

    This report describes technical opportunities to serve as parts of a technological roadmap for Shoals Technologies Group in power electronics for PV applications. There are many different power converter circuits that can be used for solar inverter applications. The present applications do not take advantage of the potential for using common modules. We envision that the development of a power electronics module could enable higher reliability by being durable and flexible. Modules would have fault current limiting features and detection circuits such that they can limit the current through the module from external faults and can identify and isolate internal faults such that the remaining modules can continue to operate with only minimal disturbance to the utility or customer. Development of a reliable, efficient, low-cost, power electronics module will be a key enabling technology for harnessing more power from solar panels and enable plug and play operation. Power electronics for computer power supplies, communication equipment, and transportation have all targeted reliability and modularity as key requirements and have begun concerted efforts to replace monolithic components with collections of common smart modules. This is happening on several levels including (1) device level with intelligent control, (2) functional module level, and (3) system module. This same effort is needed in power electronics for solar applications. Development of modular units will result in standard power electronic converters that will have a lower installed and operating cost for the overall system. These units will lead to increased adaptability and flexibility of solar inverters. Incorporating autonomous fault current limiting and reconfiguration capabilities into the modules and having redundant modules will lead to a durable converter that can withstand the rigors of solar power generation for more than 30 years. Our vision for the technology roadmap is that there is no need

  11. A system for converting print into braille.

    Science.gov (United States)

    Blenkhorn, P

    1997-06-01

    This paper describes a method for converting text into braille, in the form in which it is stored as in a computer. The system has been designed to be configurable for a wide range of languages and character sets, and uses a predominantly table driven method to achieve this. The algorithm is explained in the context of the conversion of text into Standard English Braille (British), and the tables for this transformation are given. Particular importance has been attached to enabling braille specialists, who are not experts in computer algorithms, to be able to modify the system for either slight modifications to an existing braille code translator, or for producing a braille code translator for a new language.

  12. Performance Evaluation of Wave Energy Converters

    DEFF Research Database (Denmark)

    Pecher, Arthur

    Ocean waves provide a sustainable, power-dense, predictable and widely available source of energy that could provide about 10 % of worlds energy needs. While research into waveenergy has been undertaken for decades, a significant increase in related activities has been seen in the recent years......, with more than 150 concepts currently being developed worldwide. Wave energy conversion concepts can be of many kinds, as the energy in the waves can be absorbed in many different ways. However, each concept is expected to require a thorough development process, involving different phases and prototypes....... Guidelines for the development of wave energy converters recommend the use of different prototypes, having different sizes, which have to perform tank tests or sea trials. Thisimplicates the need of different testing environment, which shifts from being controllable to uncontrollable with the development...

  13. Performance Evaluation of Wave Energy Converters

    DEFF Research Database (Denmark)

    Pecher, Arthur

    Ocean waves provide a sustainable, power-dense, predictable and widely available source of energy that could provide about 10 % of worlds energy needs. While research into wave energy has been undertaken for decades, a significant increase in related activities has been seen in the recent years......, with more than 150 concepts currently being developed worldwide. Wave energy conversion concepts can be of many kinds, as the energy in the waves can be absorbed in many different ways. However, each concept is expected to require a thorough development process, involving different phases and prototypes....... Guidelines for the development of wave energy converters recommend the use of different prototypes, having different sizes, which have to perform tank tests or sea trials. This implicates the need of different testing environment, which shifts from being controllable to uncontrollable with the development...

  14. Clustering of cycloidal wave energy converters

    Science.gov (United States)

    Siegel, Stefan G.

    2016-03-29

    A wave energy conversion system uses a pair of wave energy converters (WECs) on respective active mountings on a floating platform, so that the separation of the WECs from each other or from a central WEC can be actively adjusted according to the wavelength of incident waves. The adjustable separation facilitates operation of the system to cancel reactive forces, which may be generated during wave energy conversion. Modules on which such pairs of WECs are mounted can be assembled with one or more central WECs to form large clusters in which reactive forces and torques can be made to cancel. WECs of different sizes can be employed to facilitate cancelation of reactive forces and torques.

  15. Converting environmental documentation to management information

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, M.J.; Frentz, H.J. [Tracor Technology Resources, Inc., Rockville, MD (United States)

    1996-12-01

    The growth of environmental, health, and safety regulations and their reporting requirements has been extraordinary. Penalties for missteps in environmental documentation also grow more serious. Every major piece of environmental legislation requires facilities to collect data and maintain records, in many cases detailed records for long periods of time, on raw materials, processes, emissions, events, personnel, and many other facets of business operations. Unfortunately, for some organizations, the collection of data that satisfies regulatory requirements is an end in itself. Data acquired in this manner may result in little useful information that managers can use to foster their business goals. For organizations of any appreciable size, the volume of environmental data, in manual form, makes analysis difficult to impossible. Too often, data resides in disparate databases, in different locations, and within incompatible information management systems. This paper discusses converting these disparate databases into a useful system.

  16. Power Generation Using Mechanical Wave Energy Converter

    Directory of Open Access Journals (Sweden)

    Srinivasan Chandrasekaran

    2012-03-01

    Full Text Available Ocean wave energy plays a significant role in meeting the growing demand of electric power. Economic, environmental, and technical advantages of wave energy set it apart from other renewable energy resources. Present study describes a newly proposed Mechanical Wave Energy Converter (MEWC that is employed to harness heave motion of floating buoy to generate power. Focus is on the conceptual development of the device, illustrating details of component level analysis. Employed methodology has many advantages such as i simple and easy fabrication; ii easy to control the operations during rough weather; and iii low failure rate during normal sea conditions. Experimental investigations carried out on the scaled model of MWEC show better performance and its capability to generate power at higher efficiency in regular wave fields. Design Failure Mode and Effect Analysis (FMEA shows rare failure rates for all components except the floating buoy.

  17. Modular Power Converters for PV Applications

    Energy Technology Data Exchange (ETDEWEB)

    Ozpineci, Burak [ORNL; Tolbert, Leon M [ORNL

    2012-05-01

    This report describes technical opportunities to serve as parts of a technological roadmap for Shoals Technologies Group in power electronics for PV applications. There are many different power converter circuits that can be used for solar inverter applications. The present applications do not take advantage of the potential for using common modules. We envision that the development of a power electronics module could enable higher reliability by being durable and flexible. Modules would have fault current limiting features and detection circuits such that they can limit the current through the module from external faults and can identify and isolate internal faults such that the remaining modules can continue to operate with only minimal disturbance to the utility or customer. Development of a reliable, efficient, low-cost, power electronics module will be a key enabling technology for harnessing more power from solar panels and enable plug and play operation. Power electronics for computer power supplies, communication equipment, and transportation have all targeted reliability and modularity as key requirements and have begun concerted efforts to replace monolithic components with collections of common smart modules. This is happening on several levels including (1) device level with intelligent control, (2) functional module level, and (3) system module. This same effort is needed in power electronics for solar applications. Development of modular units will result in standard power electronic converters that will have a lower installed and operating cost for the overall system. These units will lead to increased adaptability and flexibility of solar inverters. Incorporating autonomous fault current limiting and reconfiguration capabilities into the modules and having redundant modules will lead to a durable converter that can withstand the rigors of solar power generation for more than 30 years. Our vision for the technology roadmap is that there is no need

  18. Passive components used in power converters

    CERN Document Server

    Rufer, A; Barrade, P

    2006-01-01

    In power converters, passive components play an important role, and have in general specific nature and properties. The goal of this tutorial is to give an overview, first on inductive components for power conversion, and second on dedicated power capacitors. In a third part, new components— supercapacitors—will be presented. Generally, inductors for power applications must be custom designed. In this tutorial, the most important effects encountered when realising inductive components will be presented in the first part, without entering into the detailed design of such components. For that purpose, the referenced documents that have served as a base for this tutorial must be consulted [1], [2], and mainly [3]. The second part of this tutorial (Capacitors used in power electronics) is dedicated to power capacitors. Unlike inductors, capacitors cannot be specifically designed, but must be selected from a manufacturer’s list of components. Here, the documentation corresponds to a subset of Ref. [4] that h...

  19. Intermittency in Switching Power Converters: Theoretical Analysis

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yu-fei; CHEN Jun-ning; TSE Chi K.; QIU Shui-sheng; KE Dao-ming; SHI Long-xing; SUN Wei-feng

    2006-01-01

    In view of reasonable explanation of intermittent subharmonics and chaos that can be gained from coupling filter between circuits,this paper discusses a method that maps time bifurcation with parameter bifurcation.Based on this mapping method,the general analysis method of characteristic multiplier,which is originally aimed at parameter bifurcation,can be used for the study of intermittency,i.e.,time bifurcation.In this paper,all researches coming from characteristic multipliers,parameter-bifurcation diagrams,and the largest Lyapunov exponent indicate the same results as those produced by simulation and experiment.Thus,it is proved theoretically that the intermittency in switching power converter can be explained in terms of coupling of spurious interference.

  20. Transcutaneous optical power converter for implantable devices

    Science.gov (United States)

    Tamura, Toshiyo; Shamsuddin, A. K. M.; Kawarada, Atsushi; Togawa, Tatsuo; Oberg, P. Ake

    1994-02-01

    An optical transcutaneous power converter has been developed for the power supply of implanted devices. It consists of a light source, optical fiber system and a photo detector. The light source is either a halogen lamp or continuous high-power laser diode which illuminated skin surface. The light penetrates through the skin to the solar cells. The preliminary experiments with a slice of tissue in between the light source and the solar cells showed that the power transfer efficiency was 40% in comparison to direct illumination of the solar cells. The maximum electric power obtained with a slice of tissue simulating the skin was about 8 mW at a laser diode run at a power of 100 mW. The electric power transferred is enough to supply low power consuming CMOS circuits.

  1. Converting energy from fusion into useful forms

    CERN Document Server

    Kovari, M; Jenkins, I; Kiely, C

    2014-01-01

    If fusion power reactors are to be feasible, it will still be necessary to convert the energy of the nuclear reaction into usable form. The heat produced will be removed from the reactor core by a primary coolant, which might be water, helium, molten lithium-lead, molten lithium-containing salt, or CO2. The heat could then be transferred to a conventional Rankine cycle or Brayton (gas turbine) cycle. Alternatively it could be used for thermochemical processes such as producing hydrogen or other transport fuels. Fusion presents new problems because of the high energy neutrons released. These affect the selection of materials and the operating temperature, ultimately determining the choice of coolant and working cycle. The limited temperature ranges allowed by present day irradiated structural materials, combined with the large internal power demand of the plant, will limit the overall thermal efficiency. The operating conditions of the fusion power source, the materials, coolant, and energy conversion system w...

  2. Simplifying the circuit of Josephson parametric converters

    Science.gov (United States)

    Abdo, Baleegh; Brink, Markus; Chavez-Garcia, Jose; Keefe, George

    Josephson parametric converters (JPCs) are quantum-limited three-wave mixing devices that can play various important roles in quantum information processing in the microwave domain, including amplification of quantum signals, transduction of quantum information, remote entanglement of qubits, nonreciprocal amplification, and circulation of signals. However, the input-output and biasing circuit of a state-of-the-art JPC consists of bulky components, i.e. two commercial off-chip broadband 180-degree hybrids, four phase-matched short coax cables, and one superconducting magnetic coil. Such bulky hardware significantly hinders the integration of JPCs in scalable quantum computing architectures. In my talk, I will present ideas on how to simplify the JPC circuit and show preliminary experimental results

  3. Hybrid-free Josephson Parametric Converter

    Science.gov (United States)

    Frattini, N. E.; Narla, A.; Sliwa, K. M.; Shankar, S.; Hatridge, M.; Devoret, M. H.

    A necessary component for any quantum computation architecture is the ability to perform efficient quantum operations. In the microwave regime of superconducting qubits, these quantum-limited operations can be realized with a non-degenerate Josephson junction based three-wave mixer, the Josephson Parametric Converter (JPC). Currently, the quantum signal of interest must pass through a lossy 180 degree hybrid to be presented as a differential drive to the JPC. This hybrid therefore places a limit on the quantum efficiency of the system and also increases the device footprint. We present a new design for the JPC eliminating the need for any external hybrid. We also show that this design has nominally identical performance to the conventional JPC. Work supported by ARO, AFOSR and YINQE.

  4. Radiant energy to electric energy converter

    Science.gov (United States)

    Sher, Arden (Inventor)

    1980-01-01

    Radiant energy is converted into electric energy by irradiating a capacitor including an ionic dielectric. The dielectric is a sintered crystal superionic conductor, e.g., lanthanum trifluoride, lanthanum trichloride, or silver bromide, so that a multiplicity of crystallites exist between electrodes of the capacitor. The radiant energy cyclically irradiates the dielectric so that the dielectric exhibits a cyclic photocapacitive like effect. Adjacent crystallites have abutting surfaces that enable the crystallites to effectively form a multiplicity of series capacitor elements between the electrodes. Each of the capacitor elements has a dipole layer only on or near its surface. The capacitor is initially charged to a voltage just below the dielectric breakdown voltage by connecting it across a DC source causing a current to flow through a charging resistor to the dielectric. The device can be utilized as a radiant energy detector or as a solar energy cell.

  5. Integrated Solar Power Converters: Wafer-Level Sub-Module Integrated DC/DC Converter

    Energy Technology Data Exchange (ETDEWEB)

    None

    2012-02-09

    Solar ADEPT Project: CU-Boulder is developing advanced power conversion components that can be integrated into individual solar panels to improve energy yields. The solar energy that is absorbed and collected by a solar panel is converted into useable energy for the grid through an electronic component called an inverter. Many large, conventional solar energy systems use one, central inverter to convert energy. CU-Boulder is integrating smaller, microinverters into individual solar panels to improve the efficiency of energy collection. The University’s microinverters rely on electrical components that direct energy at high speeds and ensure that minimal energy is lost during the conversion process—improving the overall efficiency of the power conversion process. CU-Boulder is designing its power conversion devices for use on any type of solar panel.

  6. High-power converters for space applications

    Science.gov (United States)

    Park, J. N.; Cooper, Randy

    1991-06-01

    Phase 1 was a concept definition effort to extend space-type dc/dc converter technology to the megawatt level with a weight of less than 0.1 kg/kW (220 lb./MW). Two system designs were evaluated in Phase 1. Each design operates from a 5 kV stacked fuel cell source and provides a voltage step-up to 100 kV at 10 A for charging capacitors (100 pps at a duty cycle of 17 min on, 17 min off). Both designs use an MCT-based, full-bridge inverter, gaseous hydrogen cooling, and crowbar fault protection. The GE-CRD system uses an advanced high-voltage transformer/rectifier filter is series with a resonant tank circuit, driven by an inverter operating at 20 to 50 kHz. Output voltage is controlled through frequency and phase shift control. Fast transient response and stability is ensured via optimal control. Super-resonant operation employing MCTs provides the advantages of lossless snubbing, no turn-on switching loss, use of medium-speed diodes, and intrinsic current limiting under load-fault conditions. Estimated weight of the GE-CRD system is 88 kg (1.5 cu ft.). Efficiency of 94.4 percent and total system loss is 55.711 kW operating at 1 MW load power. The Maxwell system is based on a resonance transformer approach using a cascade of five LC resonant sections at 100 kHz. The 5 kV bus is converted to a square wave, stepped-up to a 100 kV sine wave by the LC sections, rectified, and filtered. Output voltage is controlled with a special series regulator circuit. Estimated weight of the Maxwell system is 83.8 kg (4.0 cu ft.). Efficiency is 87.2 percent and total system loss is 146.411 kW operating at 1 MW load power.

  7. High Voltage Bi-directional Flyback Converter for Capacitive Actuator

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.

    2013-01-01

    This paper presents a high voltage DC-DC converter topology for bi-directional energy transfer between a low voltage DC source and a high voltage capacitive load. The topology is a bi-directional flyback converter with variable switching frequency control during the charge mode, and constant...... switching frequency control during the discharge mode. The converter is capable of charging the capacitive load from 24 V DC source to 2.5 kV, and discharges it to 0 V. The flyback converter has been analyzed in detail during both charge and discharge modes, by considering all the parasitic elements...... in the converter, including the most dominating parameters of the high voltage transformer viz., self-capacitance and leakage inductance. The specific capacitive load for this converter is a dielectric electro active polymer (DEAP) actuator, which can be used as an effective replacement for conventional actuators...

  8. Closed Loop Control of Soft Switched Interleaved Buck Converter

    Directory of Open Access Journals (Sweden)

    R. Shenbagalakshmi

    2012-06-01

    Full Text Available Design, Modeling and Simulation of a closed loop control is presented for Interleaved Buck Converter with Soft Switching. The features of the closed loop system are to reduce the switching losses and load current sharing among the parallel connected converters. The control system of the converter is designed using PWM technique. In order to improve the transient response and dynamic stability of the converters, the controller parameters are designed based on current mode control. Resonant components thus designed enable the application of zero current switching for both the converters connected in parallel thereby maintaining greater efficiency and minimizing voltage and current oscillations. The system analysis, design and performance are verified through simulation using MATLAB/Simulink environment. The simulation approach reveals the high speed dynamic performance of the closed loop system designed using robust PID controller. The laboratory prototype of the Buck converter is developed to verify the controller platform using PIC16F877A microcontroller.

  9. Synchronously Driven Power Converter Controller Solution for MedAustron

    CERN Document Server

    Šepetavc, Luka; Tavčar, Rok; Moser, Roland; Gutleber, Johannes

    2011-01-01

    MedAustron is an ion beam cancer therapy and research centre currently under construction in Wiener Neustadt, Austria. This facility features a synchrotron particle accelerator for light ions. Cosylab is closely working together with MedAustron on the development of a power converter controller (PCC) for the 260 deployed power converters – power supplies. Power converters deliver power to magnets used for focusing and steering particle beams. We have designed and developed software and hardware which allows integration of different types of power converters into MedAustron's control system (MACS). PCC's role is to synchronously control and monitor connected power converters. Custom real-time fibre optics link and modular front end devices have been designed for this purpose. Modular front end devices make it possible to interface with almost any type of power converter – with or without built in regulation logic. We implemented realtime mechanisms and a dedicated real-time fibre link to ...

  10. Design & Implementation of Zero Voltage Switching Buck Converter

    Directory of Open Access Journals (Sweden)

    A.Suresh Kumar

    2014-09-01

    Full Text Available Zero voltage switching (ZVS buck converter is more preferable over hard switched buck converter for low power, high frequency DC-DC conversion applications. In Zero voltage switching converter, turn on & turn off of a switch occurs at zero voltage that results in lower switching losses. In this converter soft switching is achieved by using resonant components. The optimal values of resonant components are determined by using electric functions derived from circuit configuration. This type of soft switched resonant converter offers very low electromagnetic interference (EMI.This study presents the circuit configuration with least components to realize highly efficient zero voltage switching resonant converter. It’s feasibility is confirmed with the developed proto type model and experimental results are verified.

  11. Symmetry Analysis of Thermoelectric Energy Converters with Inhomogeneous Legs

    Science.gov (United States)

    Korzhuev, M. A.

    2010-09-01

    Symmetry analysis has been applied to thermoelectric energy converters [thermoelectric generators (TEG), coolers (TEC), and heaters (TEH)] with inhomogeneous legs. The features of the crystallographic symmetry of thermoelectric materials and the symmetry of legs, thermocouples, and modules are studied. The effect of symmetry on the figure of merit Z of thermoelectric energy converters is considered. A general rule for proper placement of legs in thermoelectric converters is developed. A modified tetratomic classification for thermoelectric energy converters with inhomogeneous legs (TEGa, TEGb, TEC, and TEH) is proposed. An increase in Z for thermoelectric energy converters with inhomogeneous legs is due to the bulk thermoelectric effect. An increase in Z gives the reduction of irreversible processes in the modules (Joule heating and thermal conductivity), accompanying breaking of the symmetry of the legs. It is found that violations of the symmetry requirements can lead to significant energy losses in converters.

  12. Grid Converters for Stationary Battery Energy Storage Systems

    DEFF Research Database (Denmark)

    Trintis, Ionut

    to hours, rated at MW and MWh, battery energy storage systems are suitable and ecient solutions. Grid connection of the storage system can be done at dierent voltage levels, depending on the location and application scenario. For high power and energy ratings, increase in the battery and converter voltage...... was realized for a 100 kW active rectier to be used in a 6 kV battery energy storage test bench. In the second part, dierent solutions for power converters to interface energy storage units to medium voltage grid are given. A new modular multilevel converter concept is introduced, where the energy storage......-voltage 100 kW bidirectional grid converter, to be used in a high voltage battery energy storage test bench. The control structure proved to be stable without damping. The converter was tested in the test bench and the experimental results are presented. Multilevel converters are replacing the classical two...

  13. RISK ANALYSIS FOR SHIP CONVERTING PROJECT ACCOMPLISHMENT (Case study of KRI KP Converting Project

    Directory of Open Access Journals (Sweden)

    Dimas Endro W

    2013-10-01

    Full Text Available Ship converting has become as prospective activity in ship building area. Operational and economical aspect are the most dominant rationale. Baseon a new fuction of converted ship, a task list which contain several jobs that must be done is listed. This accomplishment schedule not only contain a task list, but also duration for certain job title. In practical apllication job duration is maintained based on experience of project manager.  Further more, total accomplish duration is setted as time accomplishment for the project. This setted time has become reference for the project bid. Occasionaly, if accomplishment time which offered is strict, than schedule slip become as potencial nightmare. For this situation, project manager has had a cristal clearconsideration to select a proper decision wheter he will take the tender offer or not. practically, project mananger has layed on his experience to handle previous project and face  penalty if the project delayed. This paper focussed on how to measure tender offer based on risk analysis, specially for converted ship tender which has a strike time accomplishment.A new application method to analysis proposed tender based on time and penalty parameter has become a topic of this paper.

  14. Grid Connected Solar PV System with SEPIC Converter Compared with Parallel Boost Converter Based MPPT

    Directory of Open Access Journals (Sweden)

    T. Ajith Bosco Raj

    2014-01-01

    Full Text Available The main objective of this work is to study the behaviour of the solar PV systems and model the efficient Grid-connected solar power system. The DC-DC MPPT circuit using chaotic pulse width modulation has been designed to track maximum power from solar PV module. The conversion efficiency of the proposed MPPT system is increased when CPWM is used as a control scheme. This paper also proposes a simplified multilevel (seven level inverter for a grid-connected photovoltaic system. The primary goal of these systems is to increase the energy injected to the grid by keeping track of the maximum power point of the panel, by reducing the switching frequency, and by providing high reliability. The maximum power has been tracked experimentally. It is compared with parallel boost converter. Also this model is based on mathematical equations and is described through an equivalent circuit including a PV source with MPPT, a diode, a series resistor, a shunt resistor, and dual boost converter with active snubber circuit. This model can extract PV power and boost by using dual boost converter with active snubber. By using this method the overall system efficiency is improved thereby reducing the switching losses and cost.

  15. Operation and maintenance strategies for wave energy converters

    DEFF Research Database (Denmark)

    Ambühl, Simon; Marquis, Laurent; Kofoed, Jens Peter;

    2015-01-01

    Inspection and maintenance costs are a significant contributor to the cost of energy for wave energy converters. There are different operation and maintenance strategies for wave energy converters. Maintenance can be performed after failure (corrective) or before a breakdown (preventive) occurs...... and maintenance costs estimations for wave energy converter applications including real weather data and damage accumulation. Furthermore, uncertainties related with costs, structural damage accumulation, inspection accuracy and different maintenance strategies can be included. This article contains a case study...

  16. Large-signal stability analysis of PWM converters

    Energy Technology Data Exchange (ETDEWEB)

    Huynh, P.T. [Philips Labs., Briarcliff Manor, NY (United States); Cho, B.H. [Seoul National Univ. (Korea, Republic of). Dept. of Electrical Engineering

    1995-12-31

    Investigation of the effects of existing nonlinearities on the stability of PWM converters is performed. The bilinear structure, the duty cycle saturation, and the opamp saturation are the principal nonlinearities in PWM converters. These nonlinearities are incorporated in the large-signal analytical models of PWM converters, and the basic input-output stability theory is applied to analyze their stability. Design and optimization of the small-signal loop gains to counteract the undesirable nonlinear effects are also discussed.

  17. Optimizing design of converters using power cycling lifetime models

    DEFF Research Database (Denmark)

    Nielsen, Rasmus Ørndrup; Munk-Nielsen, Stig

    2015-01-01

    Converter power cycling lifetime depends heavily on converter operation point. A lifetime model of a single power module switched mode power supply with wide input voltage range is shown. A lifetime model is created using a power loss model, a thermal model and a model for power cycling capability...... with a given mission profile. A method to improve the expected lifetime of the converter is presented, taking into account switching frequency, input voltage and transformer turns ratio....

  18. A new battery charger/discharger converter. [for spacecraft application

    Science.gov (United States)

    Middlebrook, R. D.; Cuk, S.; Behen, W.

    1978-01-01

    A new optimum topology dc-to-dc switching converter is extended to provide bidirectional current flow. The resulting two-quadrant converter can be employed to eliminate the discontinuous current mode in normal unidirectional applications, but is especially suited for spacecraft battery conditioning as a charge-discharge regulator in place of the conventional separate converters. Implementation of the control features and the battery charge current and voltage limits are discussed.

  19. Isolated Boost Converter with Bidirectional Operation for Supercapacitor Applications

    DEFF Research Database (Denmark)

    Hernandez Botella, Juan Carlos; Mira Albert, Maria del Carmen; Sen, Gökhan;

    2013-01-01

    This paper presents an isolated bidirectional dc/dc converter based on primary parallel isolated boost converter (PPIBC). This topology is an efficient solution in low voltage high power applications due to its ability to handle high currents in the low voltage side. In this paper, the converter ...... interconnecting two battery banks. A second prototype has been constructed and tested for supercapacitor operation in constant power charge mode....

  20. High Temperature Power Converters for Military Hybrid Electric Vehicles

    Science.gov (United States)

    2011-08-09

    M) MINI-SYMPOSIUM AUGUST 9-11 DEARBORN, MICHIGAN HIGH TEMPERATURE POWER CONVERTERS FOR MILITARY HYBRID ELECTRIC VEHICLES ABSTRACT...SUBTITLE High Temperature Power Converters for Military Hybrid Electric Vehicles 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...public release High Temperature Power Converters for Military Hybrid Electric Vehicles Page 2 of 8 I. INTRODUCTION Today, wide bandgap devices

  1. Uniform Tests of File Converters Using Unit Cubes

    Science.gov (United States)

    2015-03-01

    and easy tool. This allows BRL–CAD to act as a hub for conversion and, in turn, increases the number of users of BRL–CAD. The converters all work...Design FASTGEN Fast Shotline Generator GDiff Geometry Differences GUI graphical user interface STL STereoLithography 6 1 DEFENSE... user to convert from different geometry file types. The goal of this project is to create a uniform test for every file converter. This test is the

  2. Converting a Display Screen into a Touchscreen

    Institute of Scientific and Technical Information of China (English)

    Qun Wang; Jun Cheng; San-Ming Shen; Yi-Jiang Shen; Jian-Xin Pang

    2014-01-01

    A method is presented to convert any display screen into a touchscreen by using a pair of cameras. Most state of art touchscreens make use of special touch-sensitive hardware or depend on infrared sensors in various configurations. We describe a novel computer-vision-based method that can robustly identify fingertips and detect touch with a precision of a few millimeters above the screen. In our system, the two cameras capture the display screen image simultaneously. Users can interact with a computer by the fingertip on the display screen. We have two important contributions:first, we develop a simple and robust hand detection method based on predicted images. Second, we determine whether a physical touch takes places by the homography of the two cameras. In this system, the appearance of the display screen in camera images is inherently predictable from the computer output images. Therefore, we can compute the predicted images and extract human hand precisely by simply subtracting the predicted images from captured images.

  3. Photonic analog-to-digital converters

    Science.gov (United States)

    Valley, George C.

    2007-03-01

    This paper reviews over 30 years of work on photonic analog-to-digital converters. The review is limited to systems in which the input is a radio-frequency (RF) signal in the electronic domain and the output is a digital version of that signal also in the electronic domain, and thus the review excludes photonic systems directed towards digitizing images or optical communication signals. The state of the art in electronic ADCs, basic properties of ADCs and properties of analog optical links, which are found in many photonic ADCs, are reviewed as background information for understanding photonic ADCs. Then four classes of photonic ADCs are reviewed: 1) photonic assisted ADC in which a photonic device is added to an electronic ADC to improve performance, 2) photonic sampling and electronic quantizing ADC, 3) electronic sampling and photonic quantizing ADC, and 4) photonic sampling and quantizing ADC. It is noted, however, that all 4 classes of “photonic ADC” require some electronic sampling and quantization. After reviewing all known photonic ADCs in the four classes, the review concludes with a discussion of the potential for photonic ADCs in the future.

  4. Image processing to optimize wave energy converters

    Science.gov (United States)

    Bailey, Kyle Marc-Anthony

    The world is turning to renewable energies as a means of ensuring the planet's future and well-being. There have been a few attempts in the past to utilize wave power as a means of generating electricity through the use of Wave Energy Converters (WEC), but only recently are they becoming a focal point in the renewable energy field. Over the past few years there has been a global drive to advance the efficiency of WEC. Placing a mechanical device either onshore or offshore that captures the energy within ocean surface waves to drive a mechanical device is how wave power is produced. This paper seeks to provide a novel and innovative way to estimate ocean wave frequency through the use of image processing. This will be achieved by applying a complex modulated lapped orthogonal transform filter bank to satellite images of ocean waves. The complex modulated lapped orthogonal transform filterbank provides an equal subband decomposition of the Nyquist bounded discrete time Fourier Transform spectrum. The maximum energy of the 2D complex modulated lapped transform subband is used to determine the horizontal and vertical frequency, which subsequently can be used to determine the wave frequency in the direction of the WEC by a simple trigonometric scaling. The robustness of the proposed method is provided by the applications to simulated and real satellite images where the frequency is known.

  5. Serum angiotensin converting enzyme in pemphigus vulgaris

    Directory of Open Access Journals (Sweden)

    Reza M Robati

    2014-01-01

    Full Text Available Background: Pemphigus vulgaris is an autoimmune blistering skin disease with unknown etiology. Drugs such as angiotensin-converting enzyme (ACE inhibitors may contribute in the pathogenesis of pemphigus. Objective: We plan this essay to evaluate the serum ACE level in pemphigus vulgaris patients in comparison with healthy controls to recognize its possible role in disease pathogenesis or activity. Methods: This study was planned and performed in the dermatology clinics of Shahid Beheshti University of MedicalSciences′ Hospitals between July 2010 and June 2011. Patients with new onset of pemphigus vulgaris were enrolled in our study. Control subjects were frequency-matched to cases by sex and age. Serum ACE was determined by the spectrophotometric method. Results: Thirty-four patients with pemphigus vulgaris and 35 healthy individuals were recruited in the study. No statistical significant difference was detected in the mean level of serum ACE of the two groups (t-test, P = 0.11. The mean ACE level was significantly lower in male patients compared with male controls (P = 0.04. Moreover, a significant higher serum ACE level of patients with cutaneous involvement was observed compared to patients with mucosal involvement (P = 0.02. Conclusions: Despite lack of any significant difference of serum ACE level between pemphigus and control group, the serum ACE level was considerably lower in male pemphigus vulgaris patients compared with male controls. Therefore, ACE might have some association with pemphigus vulgaris especially in male patients; however, further studies are required to confirm this association.

  6. Another look at Statics and Dynamics of Switching Power Converters

    Science.gov (United States)

    Sasaki, Seigo; Watanabe, Haruo

    Three types of switching power supply, which are buck, boost, buck/boost converter, are statically and dynamically analysed. A framework of large signal analysis presents characteristics of converters which vary with operating points, and discusses a relationship between statics and dynamics. It is shown that boost and buck/boost converters substantially change their characteristics. There exists the operating points where for low frequencies the phases become -90° or -180° and the gains fall off to low values. The phenomenon is characterized by a zero of transfer function of the converter and also by the statics.

  7. Hybrid Voltage-Multipliers Based Switching Power Converters

    Science.gov (United States)

    Rosas-Caro, Julio C.; Mayo-Maldonado, Jonathan C.; Vazquez-Bautista, Rene Fabian; Valderrabano-Gonzalez, Antonio; Salas-Cabrera, Ruben; Valdez-Resendiz, Jesus Elias

    2011-08-01

    This work presents a derivation of PWM DC-DC hybrid converters by combining traditional converters with the Cockcroft-Walton voltage multiplier, the voltage multiplier of each converter is driven with the same transistor of the basic topology; this fact makes the structure of the new converters very simple and provides high-voltage gain. The traditional topologies discussed are the boost, buck-boost, Cuk and SEPIC. They main features of the discussed family are: (i) high-voltage gain without using extreme duty cycles or transformers, which allow high switching frequency and (ii) low voltage stress in switching devices, along with modular structures, and more output levels can be added without modifying the main circuit, which is highly desirable in some applications such as renewable energy generation systems. It is shown how a multiplier converter can become a generalized topology and how some of the traditional converters and several state-of-the-art converters can be derived from the generalized topologies and vice-versa. All the discussed converters were simulated, additionally experimental results are provided with an interleaved multiplier converter.

  8. Design of a High Efficiency Boost DC-DC Converter

    Institute of Scientific and Technical Information of China (English)

    GAO Jing; YAO Suying; XU Jiangtao; SHI Zaifeng

    2009-01-01

    An accurate circuit of PWM/PFM mode converting and a circuit of auto-adaptively adjusting dimension of power transistor are described. The duty cycle of the signal when the control mode converts can be gained accu-rately by using ratios of currents and capacitances, and an optimal dimension of power transistor is derived with different loads. The converter is designed by 0.35 μm standard CMOS technology. Simulation results indicate that the converter starts work at 0.8 V input voltage. Combined with synchronized rectification, the transfer efficiency is higher than 90% with full load range, and achieves 97.5% at rating output.

  9. Radiated electromagnetic emissions of DC-DC converters

    CERN Document Server

    Sammet, Jan Domenik

    2010-01-01

    A new powering scheme is considered to be mandatory for the CMS tracker at SLHC. The baseline solution of CMS foresees the use of DC-DC converters, allowing to provide larger currents while reducing losses. An important component of most converters are inductors, which, however, tend to radiate the switching noise generated by the converter. The radiated emissions of several converters have been measured and simulated. In addition noise susceptibility measurements with radiated noise and present CMS hardware have been performed. A summary of the results will be presented.

  10. Quantum Dot Spectrum Converters for Enhanced High Efficiency Photovoltaics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This research proposes to enhance solar cell efficiency, radiation resistance and affordability. The Quantum Dot Spectrum Converter (QDSC) disperses quantum dots...

  11. Simulation and Design Optimization of Ammonia SynthesisConverter

    Institute of Scientific and Technical Information of China (English)

    叶启亮; 应卫勇; 房鼎业

    2001-01-01

    One-dimensional pseudo-homogeneous model of an axial flow converter and one-dimensional heteroge-neous model of a horizontal converter have been presented, which describe the distribution of gaseous composition,temperature and pressure along the height in the two converters, respectively. Design optimization methods of the two converters have been proposed, by which the minimum catalyst volume can be obtained to satisfy the productive capacity of 1000 tons per day, when the operating pressure is 15.0, 10.0 and 7.5 MPa, respectively.

  12. LARGE SIGNAL DISCRETE-TIME MODEL FOR PARALLELED BUCK CONVERTERS

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    As a number of switch-combinations are involved in operation of multi-converter-system, conventional methods for obtaining discrete-time large signal model of these converter systems result in a very complex solution. A simple sampled-data technique for modeling distributed dc-dc PWM converters system (DCS) was proposed. The resulting model is nonlinear and can be linearized for analysis and design of DCS. These models are also suitable for fast simulation of these networks. As the input and output of dc-dc converters are slow varying, suitable model for DCS was obtained in terms of the finite order input/output approximation.

  13. High Efficiency Hall Thruster Discharge Power Converter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Busek leveraged previous, internally sponsored, high power, Hall thruster discharge converter development which allowed it to design, build, and test new printed...

  14. Analysis and Design of Embedded Controlled Parallel Resonant Converter

    Directory of Open Access Journals (Sweden)

    P. CHANDRASEKHAR

    2009-07-01

    Full Text Available Microcontroller based constant frequency controlled full bridge LC parallel resonant converter is presented in this paper for electrolyser application. An electrolyser is a part of renewable energy system which generates hydrogen from water electrolysis. The DC power required by the electrolyser system is supplied by the DC-DC converter. Owing to operation under constant frequency, the filter designs are simplified and utilization of magnetic components is improved. This converter has advantages like high power density, low EMI and reduced switching stresses. DC-DC converter system is simulated using MATLAB, Simulink. Detailed simulation results are presented. The simulation results are compared with the experimental results.

  15. Integrating data converters for picoampere currents from electrochemical transducers

    DEFF Research Database (Denmark)

    Breten, Madalina; Lehmann, Torsten; Bruun, Erik

    2000-01-01

    This paper describes a current mode A/D converter designed for a maximum input current range of 5 nA and a resolution of the order of 1 pA. The converter is designed for a potentiostat for amperometric chemical sensors and provides a constant polarization voltage for the measuring electrode....... A prototype chip using the dual slope conversion method has been fabricated in a 0.7 μm CMOS process. Experimental results from this converter are reported. Design problems and limitations of the converter are discussed and a new conversion technique providing a larger dynamic range and easy calibration...

  16. High Efficiency Bi-Directional Converter Used For Renewable System

    Directory of Open Access Journals (Sweden)

    M. Desal Raja

    2014-02-01

    Full Text Available This paper presents an Isolated bi-directional converter for renewable system. Voltage stress and current stress was decreses in switches. Power flows in both side. The proposed converter three phase ac voltage to dc voltage, dc voltage to three phase a.c voltage and synchronous the two voltage source. Silicon carbide diodes and bi-directional switches Mosfet’s are used for decreases the switching loss. LC Series resonant converter connected to the high efficiency. This converter power conversion control by the output voltage information.

  17. Effects of Methyl Jasmonate Treatment on Levels of Nitric Oxide and Hydrogen Peroxide and Phytoalexin Synthesis in Postharvest Grape Berries%茉莉酸甲酯处理对葡萄果实NO和H2O2水平及植保素合成的影响

    Institute of Scientific and Technical Information of China (English)

    汪开拓; 郑永华; 唐文才; 李廷君; 张卿; 尚海涛

    2012-01-01

    In order to reveal the mechanisms of methyl jasmonate(MeJA)inhibiting postharvest decay in grape berries, 'Kyoho' grape berries were pretreated with 10μmol·L-1 MeJA vapor for 6 h and then stored at 1℃ for 28 days. The fruit decay incidence, weight loss rate, levels of endogenous signaling molecules nitric oxide (NO) and hydrogen peroxide (H2O2), activities ofphytoalexin synthesis related enzymes and individual phytoalexin compounds contents were determined at 7-day intervals during the storage. The results exhibited that the MeJA treatment could significantly inhibit the increase in decay incidence and weight loss rate, promote endogenous NO release and H202 content during the early stage of the storage, and simultaneously induce the increase in activities ofphenylalanine-ammonia-lyase (PAL), cinnamate 4-hydroxylase (C4H), 4-coumarate coenzyme A ligase (4-CL) and resveratrol synthase (RS) associated with phytoalexin synthesis and the contents of phytoalexins including resveratrol and viniferin in grape berries during the storage. Therefore, we speculate that MeJA might play an important role in signal transduction in grape cells, which regulated the downstream signaling molecules NO and H202 levels to enhance activities of enzymes related to phytoalexin synthesis, resulting in promoting phytoalexin accumulation and furthermore improving disease resistance in grape berries.%以10μmol·L-1茉莉酸甲酯(Methyl jasmonate,MeJA)熏蒸处理‘巨峰’葡萄果实6h,随后转入1℃下贮藏28d。结果表明,MeJA处理显著抑制了葡萄果实在贮藏期间腐烂率和失重率的上升,促进内源NO释放量和H202含量在贮藏前期的上升,同时诱导植保素合成相关酶苯丙氨酸解氨酶(PAL)、肉桂酸-4-羟化酶(C4H)、对香豆酰-CoA连接酶(4-CL)和白藜芦醇合成酶(RS)活性以及植保素白藜芦醇和白藜芦醇脱氢二聚体含量的上升。由此推测,MeJA在

  18. Simulation and Implementation of Quasi Resonant DC-DC Converter

    Directory of Open Access Journals (Sweden)

    N. Devarajan

    2012-01-01

    Full Text Available Problem statement: A half-bridge LLC resonant converter with a voltage doubler rectifier has a simple structure and its Zero-Voltage-Switching (ZVS capability is excellent from zero to full load condition. But conduction loss is more due to high circulating energy thus reducing the system efficiency. Moreover a variable frequency control method makes the control circuits more complicated than those using the Pulse Width Modulation (PWM control method. Thus, DC drive has lower efficiency when it operates on light loads. Approach: To improve the efficiency of the DC drive under light loads, a PWM-controlled quasi-resonant converter is proposed .It has simple control circuits and less conduction loss compared to a half-bridge LLC resonant converter under light load conditions. The proposed converter has a half-bridge LLC resonant converter along with an auxiliary circuit. The load regulation of the proposed converter can be achieved by an auxiliary circuit. Thus the proposed converter is expected to be suitable sustaining power module for the efficiency enhancement of DC drives. As the magnetizing inductance of the proposed converter is larger the circulating energy is considerably reduced under light load conditions. In this study the operational principle, design and modeling of QRC DC-DC converters for DC drives are presented. The PWM controlled quasi resonant converter is implemented using PIC microcontroller 16F184A. Results: The capacitor filter in the output is replaced by pi filter to produce DC with minimum ripple. The experimental results and simulation results are compared. This converter has the advantages like reduced number of switches, reduced transformer and filter size, reduced ripple, reduced switching losses, reduced switching stresses and increased power density. Conclusion: The experimental results closely agree with the simulation results.

  19. Very High Frequency Interleaved Self-Oscillating Resonant SEPIC Converter

    DEFF Research Database (Denmark)

    Kovacevic, Milovan; Knott, Arnold; Andersen, Michael A. E.

    2013-01-01

    This paper describes analysis and design procedure of an interleaved, self-oscillating resonant SEPIC converter, suitable for operation at very high frequencies (VHF) ranging from 30 MHz to 300 MHz. The presented circuit consists of two resonant SEPIC DC-DC converters, and a capacitive...

  20. Very High Frequency Half Bridge DC/DC Converter

    DEFF Research Database (Denmark)

    Madsen, Mickey Pierre; Knott, Arnold; Andersen, Michael A. E.

    2014-01-01

    This paper presents the first, off chip, class DE (resonant half bridge) converter working in the Very High Frequency (VHF) range. The benefits of using half bridge circuits both in the inverter and rectifier part of a VHF resonant dc/dc converter are analyzed and design equations for all...

  1. BabeLO--An Extensible Converter of Programming Exercises Formats

    Science.gov (United States)

    Queiros, R.; Leal, J. P.

    2013-01-01

    In the last two decades, there was a proliferation of programming exercise formats that hinders interoperability in automatic assessment. In the lack of a widely accepted standard, a pragmatic solution is to convert content among the existing formats. BabeLO is a programming exercise converter providing services to a network of heterogeneous…

  2. Multilevel-clamped multilevel converters (MLC2)

    DEFF Research Database (Denmark)

    Rodriguez, Pedro; Bellar, Maria Dias; Muñoz-Aguliar, Raúl Santiago;

    2012-01-01

    This letter introduces a new series of multilevel (ML) converters based on the ML clamping concept. By applying this technique, a ML clamping unit (MCU) conveys additional levels for synthesizing the output waveforms of a diode-clampedML dc– ac power converter. The basic building block of the ML ...

  3. Researches Regarding the Pollution with Harmonics by the Frequency Converters

    Directory of Open Access Journals (Sweden)

    Ioan Ruja

    2008-10-01

    Full Text Available This paper presents a study regarding the influences produced by the tension and current superior harmonics if there are used frequency converters for variable speed action. There are also shown results recorded in different points of interest along with conclusions regarding which are the most suitable converters to be chosen in practical applications.

  4. Stabilizing control for power converters connected to transmission lines

    NARCIS (Netherlands)

    Zainea, Marius; Schaft, Arjan van der; Buisson, Jean

    2007-01-01

    This paper proposes a switching control strategy for the set-point stabilization of a power converter connected via a transmission line to a resistive load. The strategy employs a Lyapunov function that is directly based on energy considerations of the power converter, as well as of the transmission

  5. Impedance Coordinative Control for Cascaded Converter in Bidirectional Application

    DEFF Research Database (Denmark)

    Tian, Yanjun; Deng, Fujin; Chen, Zhe;

    2015-01-01

    difference between forward and reversed power flow. This paper addresses the analysis with the topology of cascaded dual-active-bridge converter (DAB) with inverter, and the proposed control method can also be implemented in unidirectional applications and other general cascaded converter system...

  6. BabeLO--An Extensible Converter of Programming Exercises Formats

    Science.gov (United States)

    Queiros, R.; Leal, J. P.

    2013-01-01

    In the last two decades, there was a proliferation of programming exercise formats that hinders interoperability in automatic assessment. In the lack of a widely accepted standard, a pragmatic solution is to convert content among the existing formats. BabeLO is a programming exercise converter providing services to a network of heterogeneous…

  7. Single-Phase Direct AC-AC Boost Converter

    Directory of Open Access Journals (Sweden)

    LUCANU, M.

    2014-08-01

    Full Text Available The paper presents a single-phase direct AC-AC boost converter. The circuit of the converter is simple and it has good performances, irrespective of the load nature. The adequate functioning and high performance of the circuit (the efficiency and waveform of the absorbed input current were tested both by simulation and experimentally.

  8. Pilot tones in WDM networks with wavelength converters

    DEFF Research Database (Denmark)

    Kloch, Allan; Mikkelsen, Benny; Stubkjær, Kristian

    1997-01-01

    Here we investigate the transmission of a pilot tone through an interferometric wavelength converter (IWC) in conjunction with a 2.5 Gbit/s experiment. The pilot tone is added by sinusoidal modulation of the bias current to the signal laser. After the IWC (Michelson interferometer) the converted...

  9. Primary Parallel Isolated Boost Converter with Bidirectional Operation

    DEFF Research Database (Denmark)

    Hernandez Botella, Juan Carlos; Mira Albert, Maria del Carmen; Sen, Gökhan

    2012-01-01

    This paper presents a bidirectional dc/dc converter operated with batteries both in the input and output. Primary parallel isolated boost converter (PPIBC) with transformer series connection on the high voltage side is preferred due to its ability to handle high currents in the low voltage side. ...

  10. Digital Implementation of Two Inductor Boost Converter Fed DC Drive

    Directory of Open Access Journals (Sweden)

    G. Kishor

    2011-01-01

    Full Text Available The study deals w ith simulation and implementation of two inductor boost converter fed DC drive. The two inductor boost converter fed DC drive is simulated and implemented. The circuit has advantages like higher output voltage and improved power factor. The laboratory model is implemented and the experimental results are obtained. The experimental results were compared w ith the simulation results.

  11. Intelligent dc-dc Converter Technology Developed and Tested

    Science.gov (United States)

    Button, Robert M.

    2001-01-01

    The NASA Glenn Research Center and the Cleveland State University have developed a digitally controlled dc-dc converter to research the benefits of flexible, digital control on power electronics and systems. Initial research and testing has shown that conventional dc-dc converters can benefit from improved performance by using digital-signal processors and nonlinear control algorithms.

  12. Voltage Regulator for a dc-to-dc Converter

    Science.gov (United States)

    Mclyman, C. W.

    1983-01-01

    New voltage regulator isolates signals from power-switching converter without use of complex circuitry or optical couplers. Only addition is extra secondary winding on existing interstage transformer. Error signals shortcircuit new winding and inhibit converter action. Resistor in series with primary winding limits short-circuit current to prevent damage to circuit components. Extra transformer winding eliminates need for isolation components.

  13. Gunning Mix or Converter and Electric Arc Furnace in China

    Institute of Scientific and Technical Information of China (English)

    LIUJie-hua; ZHANGYong-fang

    1996-01-01

    The increase of steel output by converter and electric are furnace has imposed a critical demand in quality and quantity on gunning mix in functioning a longer life of those de-vices linings.The paoer describes the consump-tion of gunning mix for converter and EAF and its recent development in variety and quality in China.

  14. Design of an emi output filter for frequency converters

    NARCIS (Netherlands)

    Roc'h, A.; Bergsma, H.; Leferink, F.B.J.; Zhao, D.; Polinder, H.; Ferreira, B.

    2006-01-01

    A filter has been designed to reduce conducted and radiated emission generated by a frequency converter. The frequency converter, cables and motor were modelled in order to make a good estimation of the radiated emission. A single stage output filter was designed making use of feedthrough apacitors

  15. A Boosting Multi Flyback Converter for Electric Vehicle Application

    Directory of Open Access Journals (Sweden)

    J. Sangeetha

    2015-08-01

    Full Text Available The Flyback converter belongs to the primary switched converter family, which means there is isolation between input and output. Flyback converters have low number of components compared to other Switched Mode Power Supplies (SMPSs, they also have the advantage that several isolated output voltages can be regulated by one control circuit. This study proposes an efficient and cost effective Multi Flyback topology, an isolated DC-DC converter suitable for electric vehicle applications especially driven with induction motor. The converter topology forms a power interface between the battery and the motor and also capable of boosting the voltage from low voltage battery side to high voltage DC link. A Multi Flyback Converter topology implemented by paralleling three individual flyback converters at the battery input side and DC link output side. The topology will share the current across each individual converter and the individual power will be added up at the output side. The scheme incorporates a transformer winding technique which can reduce the leakage inductance of the coupled inductor to a satisfactory limit.

  16. Charge pump DC-DC converter comprising solid state batteries

    NARCIS (Netherlands)

    Reefman, D.; Roozeboom, F.; Notten, P.H.L.; Klootwijk, J.H.

    2013-01-01

    An electronic device is provided which comprises a DC-DC converter. The DC-DC converter comprises at least one solid-state rechargeable battery (B1, B2) for storing energy for the DC-DC conversion and an output capacitor (C2).

  17. REQUIREMENTS AND CONSTRUCTIVE DIFFERENCES OF A STATIC CONVERTER

    Directory of Open Access Journals (Sweden)

    Uskov A. E.

    2015-03-01

    Full Text Available In this article technical requirements to static converters are examined. We can treat as the basic parameters: efficiency and quality of a target voltage. Weight-dimensional parameters, reliability, maintainability are basic operational parameters, as well as target capacity, size of an starting and target voltage belong to key parameters of static converters. As a rule designing of converters is a uniform constructive complex. As at designing, time of an operating time until first failure is taken into account, time of guaranteed work of the separate elements included in the static converter, are determined on the statistical data. Failure of separate elements of parts of converters are possible because of internal (time of guaranteed work and external (short circuits, overloads factors. In the article we have offered the ways of reduction of influence of external factors (for example, we used high-speed automatic switches or iterative static converters in which parts of a power circuit were included in parallel. Using universal static converters allows raising some parameters of efficiency simultaneously. In the article we have also considered a scheme of the iterative converter with variable structure which allows (depending on start and target conditions or requirements forming an output capacity of the required level and quality without constructive change

  18. Multilevel converters for UPS applications: comparison and implementation

    DEFF Research Database (Denmark)

    Lega, Alberto; Munk-Nielsen, Stig; CASADEI, Domenico

    2007-01-01

    In this paper the possibility to use multilevel converters in UPS applications is discussed. Three different converter topologies, i.e. the three-level diode-clamped, the four-level diode-clamped and the four-level Multi Point Clamped (MPC) have been firstly compared by simulation simulations to ...

  19. Multifunctional Converter Drive for Automotive Electric Power Steering Systems

    NARCIS (Netherlands)

    Hackner, T.J.

    2013-01-01

    In this thesis it is shown that in the case of an automotive electric power steering system, critical pulse power loads can be decoupled from the power net with a storage element and a multifunctional converter. A multifunctional converter system is proposed because it uses the motor drive system as

  20. Low input voltage converter/regulator minimizes external disturbances

    Science.gov (United States)

    1966-01-01

    Low-input voltage converter/regulator constructed in a coaxial configuration minimizes external magnetic field disturbance, suppresses radio noise interference, and provides excellent heat transfer from power transistors. It converts the output of fuel and solar cells, thermionic diodes, thermoelectric generators, and electrochemical batteries to a 28 V dc output.

  1. Four-quadrant flyback converter for direct audio power amplification

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2005-01-01

    This paper presents a bidirectional, four-quadrant flyback converter for use in direct audio power amplification. When compared to the standard Class-D switching audio power amplifier with a separate power supply, the proposed four-quadrant flyback converter provides simple solution with better...

  2. Three-channel integrating analog-to-digital converter

    Science.gov (United States)

    Stevens, G. L.

    1978-01-01

    A three-channel integrating analog-to-digital converter was added to the complex mixer system to accept the baseband, complex signals generated by the complex mixers and output binary data to the digital demodulator for further processing and recording. The converter was first used for processing multistation data in radar experiments in the spring of 1977.

  3. Wave Dragon Wave Energy Converters Used as Coastal Protection

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Harck; Andersen, Thomas Lykke; Kofoed, Jens Peter

    2011-01-01

    This paper deals with wave energy converters used to reduce the wave height along shorelines. For this study the Wave Dragon wave energy converter is chosen. The wave height reduction from a single device has been evaluated from physical model tests in scale 1:51.8 of the 260 x 150 m, 24 kW/m model...

  4. A Level Converter provided with Slew-Rate Controlling Means

    NARCIS (Netherlands)

    Annema, Anne J.

    2000-01-01

    A level converter for the converting of a first digital signal (U1) having a first voltage range into a second digital signal (U2) having a second voltage range comprising an amplifier (T0) having an input for receiving the first digital signal (U1) and an output for supplying the second digital

  5. A Single Switch Dual Output Non-Isolated Boost Converter

    DEFF Research Database (Denmark)

    Klimczak, Pawel; Munk-Nielsen, Stig

    2008-01-01

    very simple dual output non-isolated boost converter is presented. Single active switch is used to control both, positive and negative output voltages. The converter is desired to boost unregulated low input voltage 25-50 Vdc to regulated high voltage ±400 Vdc in dual dc-link. In this paper proposed...

  6. Pricing of convertible bonds with hard call features

    NARCIS (Netherlands)

    Wever, Jolle O.; Smid, Peter P.M.; Koning, Ruud H.

    2002-01-01

    This paper discusses the development of a valuation model for convertible bonds with hard call features. We define a hard call feature as the possibility for the issuer to redeem a convertible bond before maturity by paying the call price to the bondholder. We use the binomial approach to model conv

  7. Analysis of a novel phase-shifted soft switch converter

    Institute of Scientific and Technical Information of China (English)

    蒋志宏; 黄立培; 张义

    2002-01-01

    In this paper, on the basis of the phase-shifted controlled zero-voltage-switch (ZVS) full-bridge converter with pulse width modulation (PWM), a novel zero-voltage and zero-current switch (ZVZCS) PWM converter using a simple auxiliary circuit was designed. The ZVZCS soft switch is achieved by the resonance among the resisting electromagnetic deflection capacitor, the capacitor of the simple auxiliary network and the leakage inductor of transformer. There are no dissipation devices of the saturation inductor and the auxiliary switch in the converter, meantime the capacitor of the auxiliary circuit is also used to clamp the voltage of the rectifier, and there is no additional clamped circuit. There is no big circulating current in the converter, all the active and passive devices work on the condition of the low current and voltage stress, and the proposed converter has wide load range and small duty loss.

  8. An Innovative Reconfigurable Integrated Converter Topology Suitable for Distributed Generation

    Directory of Open Access Journals (Sweden)

    Renato Rizzo

    2012-09-01

    Full Text Available The electricity market and environmental concerns, with wide utilization of renewable sources, have improved the diffusion of distributed generation units changing the operations of distribution grids from passive networks to microgrids. A microgrid includes a cluster of electrical loads, energy storage devices and microsources, which provide both power and heat to their local area. A microgrid has usually one connection point to the utility grid through power electronic converters placed at customers’ sites. This paper analyses a Reconfigurable Integrated Converter (RIC used for a domestic microgrid with inputs from the AC mains and photovoltaic arrays, and two DC outputs at different voltage levels. A RIC as a dual-boost DC-DC converter is proposed, modelled and analysed in the paper. The advantages of such a topology in comparison with traditional boost converters are outlined. Reported simulations results give evidence on the controllability of this converter and the capability of achieving the desired voltage outputs with reduced ripple.

  9. Optimization of DC-DC Converters via Geometric Programming

    Directory of Open Access Journals (Sweden)

    U. Ribes-Mallada

    2011-01-01

    Full Text Available The paper presents a new methodology for optimizing the design of DC-DC converters. The magnitudes that we take into account are efficiency, ripples, bandwidth, and RHP zero placement. We apply a geometric programming approach, because the variables are positives and the constraints can be expressed in a posynomial form. This approach has all the advantages of convex optimization. We apply the proposed methodology to a boost converter. The paper also describes the optimum designs of a buck converter and a synchronous buck converter, and the method can be easily extended to other converters. The last example allows us to compare the efficiency and bandwidth between these optimal-designed topologies.

  10. Zero-voltage switching technique in dc/dc converters

    Science.gov (United States)

    Liu, Kwang-Hwa; Lee, Fred C. Y.

    1990-07-01

    A novel resonant switch operating under the principle of zero-voltage switching is presented. In contrast to the zero-current switching, this technique eliminates the switching loss and dv/dt noise due to the discharging of MOSFET junction capacitances and the reverse recovery of diodes, and enables the converters to operate at high frequencies. A dc analysis of the converter is carried out. The duality relationship between the zero-current switching technique and the zero-voltage switching technique is derived. The two techniques are compared using an example showing the duality between a current-mode quasi-resonant Buck converter and a voltage-mode quasi-resonant boost converter. A 5-MHz 50 V to 5 V flyback converter employing the zero-voltage switching technique has been implemented. The circuit contains the smallest number of components possible, and yet maintains high efficiency at high switching frequency.

  11. CIECA - Application to current programmed switching Dc-Dc converters

    Science.gov (United States)

    Chetty, P. R. K.

    1982-09-01

    The current injection equivalent circuit approach (CIECA) to modeling switching converter power stages is extended to model the current programmed converter power stages operating in fixed frequency, continuous inductor conduction mode. To demonstrate the method, modeling is carried out for the buck, boost, and buckboost converters to obtain small-signal linear equivalent circuit models which represent both input and output properties. The results of these analyses are presented in the form of linear equivalent circuit models as well as transfer functions. Though current programmed converters exhibit single-pole response, the addition of artificial ramp changes converters to exhibit well damped two-pole response. This has been investigated for the first time using CIECA. The results of these analyses are presented in the form of linear equivalent circuit models as well as transfer functions.

  12. Dividends Sharing Convertible Bonds Pricing and Numerical Evaluation

    Directory of Open Access Journals (Sweden)

    Xu Guo

    2013-01-01

    Full Text Available The convertible bond is becoming one of the most important financial instruments for the company to raise capital fund since it was first issued by American New York Erie Company in 1843. In this paper, it is the first time to study the pricing problem for convertible bond whose underlying stocks pay dividends via the reflected backward stochastic differential equations. Associating the solutions of reflected BSDEs with the obstacle problems for nonlinear parabolic PDEs, we establish the pricing formulas for convertible bonds with continuous and discrete dividends by means of the viscosity solutions for some PDEs. Besides, we also derive the price of convertible bonds with higher borrowing rate which is realistic in the financial market. Then the numerical evaluations are provided by the radial basis functions method. Moreover, we discuss the influence of dividends paying as well as higher borrowing rate on the convertible bond price at last.

  13. Design of Monolithic Integrator for Strain-to-Frequency Converter

    Directory of Open Access Journals (Sweden)

    Tuan Mohd. Khairi Tuan Mat

    2012-01-01

    Full Text Available Strain-to-Frequency converter (SFC is a one of the analog conditioner tools that converts any strain signal to the frequency signal. The basic concept of SFC is by detecting any changing of strains, then converting the strain to the voltage signal and converting the voltage signal to the frequency signal. This tool consists of 3 main  components which are strain gauge, differential integrator and comparator. This paper presents the designing and analysis of monolithic integrator that to be used in the Strain-toFrequency converter. The primary goal is to design and simulate the performance of monolithic integrator for SFC using GATEWAY Silvaco Electronic Design Automation (S EDA tools and EXPERT software. The performances of SFC using the designed monolithic integrator are also investigated.

  14. High-feedback Operation of Power Electronic Converters

    DEFF Research Database (Denmark)

    Zhusubaliyev, Zhanybai T.; Mosekilde, Erik; Andriyanov, Alexey I.;

    2013-01-01

    The purpose of this review is to provide a survey of some of the most important bifurcation phenomena that one can observe in pulse-modulated converter systems when operating with high corrector gain factors. Like other systems with switching control, electronic converter systems belong to the cl......The purpose of this review is to provide a survey of some of the most important bifurcation phenomena that one can observe in pulse-modulated converter systems when operating with high corrector gain factors. Like other systems with switching control, electronic converter systems belong...... or resonant periodic dynamics on the surface of a two-dimensional torus. This transition occurs when the feedback gain is increased beyond a certain threshold, for instance in order to improve the speed and accuracy of the output voltage regulation. For each of the three converter types, we discuss a number...

  15. The New Modular Control System for Power Converters at CERN

    CERN Document Server

    Di Cosmo, Matteo

    2015-01-01

    The CERN accelerator complex consists of several generations of particle accelerators, with around 5000 power converters supplying regulated current and voltage to normal and superconducting magnet circuits. Today around 12 generations of converter control platforms can be found in the accelerator complex, ranging in age and technology. The diversity of these platforms has a significant impact on operability, maintenance and support of power converters. Over the past few years a new generation of modular controls called RegFGC3 has been developed by CERN’s power conversion group, with a goal to provide a standardised control platform, supporting a wide variety of converter topologies. The aim of this project is to reduce maintenance costs by decreasing the variety and diversity of control systems whilst simultaneously improving the operability and reliability of power converters and their controls. This paper describes the state of the on-going design and realization of the RegFGC3 platform, focusing on fun...

  16. A study of Schwarz converters for nuclear powered spacecraft

    Science.gov (United States)

    Stuart, Thomas A.; Schwarze, Gene E.

    1987-01-01

    High power space systems which use low dc voltage, high current sources such as thermoelectric generators, will most likely require high voltage conversion for transmission purposes. This study considers the use of the Schwarz resonant converter for use as the basic building block to accomplish this low-to-high voltage conversion for either a dc or an ac spacecraft bus. The Schwarz converter has the important assets of both inherent fault tolerance and resonant operation; parallel operation in modular form is possible. A regulated dc spacecraft bus requires only a single stage converter while a constant frequency ac bus requires a cascaded Schwarz converter configuration. If the power system requires constant output power from the dc generator, then a second converter is required to route unneeded power to a ballast load.

  17. A new configuration for multilevel converters with diode clamped topology

    DEFF Research Database (Denmark)

    Nami, A.; Zare, F.; Ledwich, G.

    2008-01-01

    of load changes which can avoid neutral point balancing problem in such converters. In addition, the presented topology is suitable for renewable energy systems to boost the low rectified output-voltage. In order to verify the proposed topology, steady state analysis, modelling and simulations are carried......Due to the increased use of renewable energy and power elctronic applications, more multilevel converters (MLC) are developed. A Neutral Point Clamped (NPC) inverter is one of the most used multilevel topologies for wind turbine (WT) and photovoltaic (PV) applications. One of the most crucial...... points in this type of converter is dc-voltage control. In this paper, a novel multi output dc-dc converter connected to a diode clamped topology is presented. This converter, for a given duty cycles, is able to regulate the capacitor voltage to provide an appropriate input voltage for NPC regardless...

  18. Angiotensin converting enzyme genotype in cardiovascular disease

    Energy Technology Data Exchange (ETDEWEB)

    Summers, K.M.; Huggard, P.R.; West, M.J. [Univ. of Queensland, Brisbane (Australia)] [and others

    1994-09-01

    Angiotensin converting enzyme (ACE) catalyses formation of angiotensin II and degradation of bradykinin, vasoactive peptides with opposing properties. The result of ACE action is to promote vasoconstriction and cell growth. PCR is used to detect a common polymorphism due to the insertion of an Alu repeat element of 287 bp into intron 16. ACE genotype has been implicated in risk for myocardial infarction (MI) and hypertension in humans. We have studied a group of 640 patients (61% male aged 64 {plus_minus} 11 years) with myocardial ischaemic syndromes, followed for 12 months after initial hospital admission. In this group, the frequency of the insertion (I) allele was 0.47 (N=1170 chromosomes), not significantly higher than the frequency of 0.46 in 112 local blood donors (50% male aged 59 {plus_minus}5 years). In the 300 patients with diagnosed MI, I allele frequency was 0.48. This is significantly higher ({chi}{sup 2}=5.78, P=0.015) than the frequency of 0.42 reported in a multi-centre study of ACE genotype in 600 male European patients with MI . There was a non-significant increase in the frequency of a cardiac event within 6 months of hospital admission in those of II genotype (N=464, 47 events to date). These results suggest that in our population, the I allele and/or II genotype may be associated with risk of MI. This contrasts with the study cited above, where the D (deletion) allele and DD genotype frequency were raised in patients compared with controls. Hypertension is associated with the ACE D allele, and does not explain the heart disease risk, which may be associated with the I allele, in this group of survivors of myocardial ischaemic disease. The difference between our results and the previous study may be due to ascertainment or ethnic differences or to problems amplifying the I allele in some heterozygotes. Clearly, the role of ACE genotype in these diseases is complex.

  19. Caracterização parcial de frações obtidas de extratos de Cymbopogon nardus com atividade elicitora de fitoalexinas em sorgo e soja e efeito sobre Colletotrichum lagenarium Partial characterization of fractions from extracts of Cymbopogon nardus with elicitor activity of phytoalexins in sorghum and soy and effect on Colletotrichum lagenarium

    Directory of Open Access Journals (Sweden)

    Carla Giovane Ávila Moreira

    2008-12-01

    Full Text Available Plantas medicinais apresentam potencial para o controle de fitopatógenos devido ao efeito direto sobre o agente patogênico ou indireto pela ativação de mecanismos de defesa como as fitoalexinas. Assim, o presente trabalho teve por objetivo verificar o efeito antifúngico e elicitor de frações obtidas da citronela (Cymbopogon nardus, a partir dos extratos brutos metanólico (EME e etanólico (EET dessa planta. Os extratos EME e EET foram fracionados em cromatógrafo de coluna de filtração em gel (CFG obtendo-se três frações a partir do extrato metanólico (FMI, FMII e FMIII e duas frações para o extrato etanólico (FEI e FEII. Os pesos moleculares para as frações FMI, FMII, FMIII, FEI e FEII foram 69,29; 40,51; 18,72; 65,89 e 24,11 kDa, respectivamente. As frações obtidas nas CFG foram utilizadas em bioensaios de germinação de esporos e formação de apressórios por Colletotrichum lagenarium e, de indução de fitoalexinas em mesocótilos de sorgo e cotilédones de soja. Observou-se que não houve efeito significativo das frações de EME e EET analisadas sobre a germinação e formação de apressórios pelo patógeno. Quanto ao acúmulo de fitoalexinas em cotilédones de soja, não houve efeito significativo das frações FMI, FMII, FMIII, FEI e FEII. Entretanto, observou-se efeito significativo das frações obtidas na CFG, sobre a produção de fitoalexinas em mesocótilos de sorgo, onde os maiores acúmulos destas fitoalexinas foram promovidas pelas frações FMI e FMIII, diferindo significativamente do tratamento controle. Com base nos resultados obtidos, é possível concluir que frações parcialmente purificadas obtidas de EME de C. nardus apresentam potencial para induzir o acúmulo de fitoalexinas em mesocótilos de sorgo.Medicinal plants present potential to control phytopathogens due to the direct effect or by the activation of defense mechanisms like phytoalexins. Then, the present work had the objective to

  20. Novel family of quasi-Z-source DC/DC converters derived from current-fed push-pull converters

    DEFF Research Database (Denmark)

    Chub, Andrii; Husev, Oleksandr; Vinnikov, Dmitri

    2014-01-01

    This paper is devoted to the step-up quasi-Z-source dc/dc push-pull converter family. The topologies in the family are derived from the isolated boost converter family by replacing input inductors with the quasi-Z-source network. Two new topologies are proposed, analyzed and compared. Theoretical...

  1. Analysis of series resonant converter with series-parallel connection

    Science.gov (United States)

    Lin, Bor-Ren; Huang, Chien-Lan

    2011-02-01

    In this study, a parallel inductor-inductor-capacitor (LLC) resonant converter series-connected on the primary side and parallel-connected on the secondary side is presented for server power supply systems. Based on series resonant behaviour, the power metal-oxide-semiconductor field-effect transistors are turned on at zero voltage switching and the rectifier diodes are turned off at zero current switching. Thus, the switching losses on the power semiconductors are reduced. In the proposed converter, the primary windings of the two LLC converters are connected in series. Thus, the two converters have the same primary currents to ensure that they can supply the balance load current. On the output side, two LLC converters are connected in parallel to share the load current and to reduce the current stress on the secondary windings and the rectifier diodes. In this article, the principle of operation, steady-state analysis and design considerations of the proposed converter are provided and discussed. Experiments with a laboratory prototype with a 24 V/21 A output for server power supply were performed to verify the effectiveness of the proposed converter.

  2. Architecture for a High-to-Medium-Voltage Power Converter

    Science.gov (United States)

    Vorpenian, Vatche

    2008-01-01

    A power converter now undergoing development is required to operate at a DC input potential ranging between 5.5 and 10 kV and a DC output potential of 400 V at a current up to 25 A. This power converter is also required to be sufficiently compact and reliable to fit and operate within the confines of a high-pressure case to be lowered to several miles (approx.5 km) below the surface of the ocean. The architecture chosen to satisfy these requirements calls for a series/ parallel arrangement of 48 high-frequency, pulse-width-modulation (PWM), transformer-isolation DC-to-DC power converter blocks. The input sides of the converter blocks would be connected in series so that the input potential would be divided among them, each of them being exposed to an input potential of no more than 10 kV/48 . 210 V. The series connection of inputs would also enforce a requirement that all the converter blocks operate at the same input current. The outputs of the converter blocks would be connected in a matrix comprising 6 parallel legs, each leg being a cascade of eight outputs wired in series (see figure). All the converter blocks would be identical within the tolerances of the values of their components. A single voltage feedback loop would regulate the output potential. All the converter blocks would be driven by the same PWM waveform generated by this feedback loop. The power transformer of each converter block would have a unity turns ratio and would be capable of withstanding as much as 10 kVDC between its primary and secondary windings. (Although, in general, the turns ratio could be different from unity, the simplest construction for minimizing leakage and maximizing breakdown voltage is attained at a turns ratio of unity.)

  3. Pulse-width modulated DC-DC power converters

    CERN Document Server

    Kazimierczuk, Marian K

    2008-01-01

    This book studies switch-mode power supplies (SMPS) in great detail. This type of converter changes an unregulated DC voltage into a high-frequency pulse-width modulated (PWM) voltage controlled by varying the duty cycle, then changes the PWM AC voltage to a regulated DC voltage at a high efficiency by rectification and filtering. Used to supply electronic circuits, this converter saves energy and space in the overall system. With concept-orientated explanations, this book offers state-of-the-art SMPS technology and promotes an understanding of the principle operations of PWM converters,

  4. Nonlinear Phenomena in Buck-Boost Power Factor Correction Converter

    Directory of Open Access Journals (Sweden)

    Mehrnoosh Vatani

    2013-01-01

    Full Text Available Buck-Boost Power-Factor-Correction (PFC converter with Average-Current-Model (ACM control is a nonlinear circuit because of the multiplier using and large change in the duty cycle, so its stability analysis must be studied by nonlinear model. In this paper double averaging method is used for describing the model of this converter. By this model we would be able to explain the low frequency dynamics of the system and identify stability boundaries according to circuit parameters and also nonlinear phenomena of this converter are detected.

  5. Radiated electromagnetic emissions of DC-DC converters

    Energy Technology Data Exchange (ETDEWEB)

    Feld, L; Jussen, R; Karpinski, W; Klein, K; Sammet, J; Wlochal, M, E-mail: sammet@cern.ch [Physikalisches Institut IB, RWTH Aachen University, Aachen (Germany)

    2010-12-15

    For the CMS tracker at SLHC a new powering scheme is considered to be mandatory to allow the detector to provide at least the same performance as today at the LHC. The baseline solution of CMS foresees the use of DC-DC converters to provide larger currents with smaller losses. An important component of most converters are inductors which, however, tend to radiate the switching noise generated by the converter. The emissions of different inductors have been measured and simulated, the coil design has been optimized and noise susceptibility measurements, with present CMS hardware, have been performed. This article summarizes the results.

  6. Sliding mode control of switching power converters techniques and implementation

    CERN Document Server

    Tan, Siew-Chong; Tse, Chi-Kong

    2011-01-01

    Sliding Mode Control of Switching Power Converters: Techniques and Implementation is perhaps the first in-depth account of how sliding mode controllers can be practically engineered to optimize control of power converters. A complete understanding of this process is timely and necessary, as the electronics industry moves toward the use of renewable energy sources and widely varying loads that can be adequately supported only by power converters using nonlinear controllers.Of the various advanced control methods used to handle the complex requirements of power conversion systems, sliding mode c

  7. Converting an NFA to a DFA with programming C++

    Directory of Open Access Journals (Sweden)

    M. Davoudi-Monfared

    2015-12-01

    Full Text Available In Automata Theory, if a language is recognized bay a Non-deterministic finite automaton (NFA, then we must show the existence of deterministic finite automaton (DFA that also recognizes it. There are many idea and algorithms to convert an NFA in to an equivalent DFA that simulates the NFA. In this paper, we present an algorithm to convert an NFA to a DFA with programming by C++. This approach contains several classes and is so universal that cover converting from NFA to DFA completely.

  8. A DSP controlled one-to-three phase matrix converter

    Energy Technology Data Exchange (ETDEWEB)

    Dubovsky, J.; Dobrucly, B; Tabacek, R.; Havrila, R. [Department of Electric Traction and Energetics Faculty of Electrical Engineering, University of Zilina (Slovakia)

    1997-12-31

    This paper deals with the theoretical analysis computer simulation and experimental results of IM fed by a one-to-three phase matrix converter which offers a unique solution for single phase electric traction applications. The proposed drive in comparison with currently used conventional drives reduces the number of power switching elements of the converter, which increases drives dependability and brings lower investment in power electronics used in drive. Further advantage is that the converter is controlled with nearly unity power factor which cuts down the operational expenses and offers higher overall performance of the drive. (orig.) 6 refs.

  9. Thyristor voltage converter in induction electric drives with microprocessor control

    Energy Technology Data Exchange (ETDEWEB)

    Braslavsky, I.; Zuzev, A.; Shilin, S. [Electric Drive Department, Urals State Technical University, Ekaterinburg (Russian Federation)

    1997-12-31

    The paper consists of some results on developed pulse model of thyristor voltage converter which is one of the most mathematically complicated unit of electric drive. The model structure and model parameter calculating method are represented. The application of the model allows to analyse stability in `locally` by the linear pulse system theory methods with talking into consideration quantise processes within the converter. Such application provides the obtaining higher accurate results comparing with the non-linear system theory approximate methods. Logarithmic frequency characteristics are used to analyse converter dynamic features and they are represented too. (orig.) 4 refs.

  10. New active load voltage clamp for HF-link converters

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.; Andersen, M.A.E.

    2005-07-01

    This paper proposes a new active clamp for HF-link converters, which features very high efficiency by returning the clamped energy back to the primary side through a small auxiliary converter. It also increases the reliability of HF-link converters by providing an alternative load current path during malfunctions of the secondary bidirectional bridge. The feasibility of the approach is shown on audio power amplifier prototype. New integrated magnetics design is presented that incorporates both the main power and auxiliary transformer on the same magnetic core. (au)

  11. Closed Loop Analysis of Bridgeless SEPIC Converter for Drive Application

    Directory of Open Access Journals (Sweden)

    Gopinath Mani

    2015-06-01

    Full Text Available In this paper closed loop analysis of Single phase AC-DC Bridgeless Single Ended Primary Inductance Converter (SEPIC for Power Factor Correction (PFC rectifier is analyzed. In this topology the absence of an input diode bridge and the due to presence of two semiconductor switches in the current flowing path during each switching cycle which will results in lesser conduction losses and improved thermal management compared to the conventional converters. In this paper the operational principles, Frequency analysis, and design equations of the proposed converter are described in detail. Performance of the proposed SEPIC PFC rectifier are carried out using Matlab Simulink software and results are presented.

  12. Atomic Electronic Contract Protocol Based on Convertible Signature

    Institute of Scientific and Technical Information of China (English)

    LIU Yi-chun; WANG Li-na; ZHANG Huan-guo

    2005-01-01

    A new class of atomicity, namely contract atomicity is presented. A new technical strategy based on convertible signature and two-phase commitment is proposed for implementing atomicity of electronic contract protocol. A new atomic contract signing protocol is given out by using ElGamal-like convertible undeniable signature and commitment of conversion key, and another new atomic contract signing protocol is brought forward by using RSA-based convertible undeniable signature scheme and commitment of conversion key.These two new protocols are proved to be of atomicity, fairness, privacy, non-repudiation.

  13. Weather satellite picture receiving stations, APT digital scan converter

    Science.gov (United States)

    Vermillion, C. H.; Kamowski, J. C.

    1975-01-01

    The automatic picture transmission digital scan converter is used at ground stations to convert signals received from scanning radiometers to data compatible with ground equipment designed to receive signals from vidicons aboard operational meteorological satellites. Information necessary to understand the circuit theory, functional operation, general construction and calibration of the converter is provided. Brief and detailed descriptions of each of the individual circuits are included, accompanied by a schematic diagram contained at the end of each circuit description. Listings of integral parts and testing equipment required as well as an overall wiring diagram are included. This unit will enable the user to readily accept and process weather photographs from the operational meteorological satellites.

  14. Choosing to convert to critical access hospital status.

    Science.gov (United States)

    Dalton, Kathleen; Slifkin, Rebecca; Poley, Stephanie; Fruhbeis, Melissa

    2003-01-01

    The authors profile facilities converting to critical access hospitals (CAHs) from 1998-2000, comparing characteristics of their communities, operations, and finances to those of other small rural providers. Counties where CAHs are located are more sparsely populated, but do not have substantially different sociodemographic profiles than other rural counties. Converting hospitals' acute daily census averaged well below the statutory limit of 15, but over one-half reduced unused bed capacity to meet CAH size limitations. The average case-mix adjusted Medicare cost per case was 16-percent higher for CAH converters than for other small hospitals and their financial ratios were substantially worse, although many other operating characteristics were similar.

  15. HIGHLY SENSITIVE TIMER-BASED RESISTANCE DEVIATION TO TIME CONVERTER

    Directory of Open Access Journals (Sweden)

    Sheroz Khan

    2012-02-01

    Full Text Available Based on an inexpensive popular precision timing chip 555 timer, a resistance to time converter is proposed in this paper which is indeed capable of converting resistive and capacitive changes into pulse widths of proportional durations. This converter exhibits a compatibility of wider conversion range with a reasonable level of sensitivity required for industrial applications. The circuit is expected to have utility in oil and water supply schemes. Simulated results are shown to be compared with mathematical derivations, both reporting a good level of resemblance and similarities.

  16. SINGLE PHASE HIGH FREQUENCY AC CONVERTER FOR INDUCTION HEATING APPLICATION

    Directory of Open Access Journals (Sweden)

    M.A INAYATHULLAAH,

    2010-12-01

    Full Text Available The proposed topology reduces the total harmonic distortion (THD of a high frequency AC/AC Converter well below the acceptable limit. This paper deals with a novel single phase AC/DC/AC soft switching utility frequency AC to high frequency AC converter. In this paper a single phase full bridge inverter with Vienna rectifier as front end is used instead of conventional diode bridge rectifier to provide continuous sinusoidal input current with nearly unity power factor at the source side with extremely low distortion.. This power converter is more suitable and acceptable for cost effective high frequency (HF consumer induction heating applications.

  17. The Research Process on Converter Steelmaking Process by Using Limestone

    Science.gov (United States)

    Tang, Biao; Li, Xing-yi; Cheng, Han-chi; Wang, Jing; Zhang, Yun-long

    2017-08-01

    Compared with traditional converter steelmaking process, steelmaking process with limestone uses limestone to replace lime partly. A lot of researchers have studied about the new steelmaking process. There are much related research about material balance calculation, the behaviour of limestone in the slag, limestone powder injection in converter and application of limestone in iron and steel enterprises. The results show that the surplus heat of converter can meet the need of the limestone calcination, and the new process can reduce the steelmaking process energy loss in the whole steelmaking process, reduce carbon dioxide emissions, and improve the quality of the gas.

  18. Parallel Stirling Converters Being Developed for Spacecraft Onboard Power

    Science.gov (United States)

    Thieme, Lanny G.

    1999-01-01

    Stirling Technology Co., as part of a NASA Lewis Research Center Phase II Small Business Innovation Research contract, has successfully demonstrated paralleling two thermodynamically independent Stirling converters. A system of four Stirling converters is being developed by NASA and the Department of Energy as an alternative high-efficiency radioisotope power source for spacecraft onboard electric power for NASA deep space missions. The high Stirling efficiency, exceeding 20 percent for this application, will greatly reduce the necessary isotope inventory in comparison to the current radioisotope thermoelectric generators (RTG s), significantly reducing mission cost and risk. Stirling is the most developed converter option of the advanced power technologies under consideration.

  19. New active load voltage clamp for HF-link converters

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2005-01-01

    This paper proposes a new active clamp for HF-link converters, which features very high efficiency by returning the clamped energy back to the primary side through a small auxiliary converter. It also increases the reliability of HF-link converters by providing an alternative load current path du...... during malfunctions of the secondary bidirectional bridge. The feasibility of the approach is shown on audio power amplifier prototype. New integrated magnetics design is presented that incorporates both the main power and auxiliary transformer on the same magnetic core....

  20. Time-interleaved analog-to-digital converters

    CERN Document Server

    Louwsma, Simon; Nauta, Bram

    2010-01-01

    ""Time-interleaved Analog-to-Digital Converters"" describes the research performed on low-power time-interleaved ADCs. A detailed theoretical analysis is made of the time-interleaved Track & Hold, since it must be capable of handling signals in the GHz range with little distortion, and minimal power consumption. Timing calibration is not attractive, therefore design techniques are presented which do not require timing calibration. The design of power efficient sub-ADCs is addressed with a theoretical analysis of a successive approximation converter and a pipeline converter. It turns out that t

  1. Soft switching buck-boost converter for photovoltaic power generation; Taiyoko hatsuden no tame no soft switching shokoatsu converter

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H. [Kyungnam University (Korea, Republic of)

    1996-10-27

    A soft switching method with small switching loss was proposed for the purpose of increasing the efficiency of a DC-DC boost converter which converted a DC current generated by solar cells to a variable DC current. Existing current converters are supplemented by using a snubber circuit around the switch so as to protect the switch by a hard switching action. However, with an increase of the output current, snubber loss is increased, reducing the efficiency. In order to solve this problem, the partial resonant switch method was applied to the converter; with this method of partially forming a resonant circuit only at the time of turning on/off of the switch, the switching loss was reduced through the soft switching, thereby making the proposed converter operate with high efficiency. Moreover, the resonant element of the partial resonant circuit using a snubber condenser, the energy accumulated in the condenser was regenerated on the power supply side without loss of snubber. With the regenerated energy, the proposed converter was provided with a smaller ratio of switching to use than the conventional converter. 4 refs., 7 figs., 1 tab.

  2. Computer simulations of optimum boost and buck-boost converters

    Science.gov (United States)

    Rahman, S.

    1982-01-01

    The development of mathematicl models suitable for minimum weight boost and buck-boost converter designs are presented. The facility of an augumented Lagrangian (ALAG) multiplier-based nonlinear programming technique is demonstrated for minimum weight design optimizations of boost and buck-boost power converters. ALAG-based computer simulation results for those two minimum weight designs are discussed. Certain important features of ALAG are presented in the framework of a comprehensive design example for boost and buck-boost power converter design optimization. The study provides refreshing design insight of power converters and presents such information as weight annd loss profiles of various semiconductor components and magnetics as a function of the switching frequency.

  3. Computer simulations of optimum boost and buck-boost converters

    Science.gov (United States)

    Rahman, S.

    1982-09-01

    The development of mathematicl models suitable for minimum weight boost and buck-boost converter designs are presented. The facility of an augumented Lagrangian (ALAG) multiplier-based nonlinear programming technique is demonstrated for minimum weight design optimizations of boost and buck-boost power converters. ALAG-based computer simulation results for those two minimum weight designs are discussed. Certain important features of ALAG are presented in the framework of a comprehensive design example for boost and buck-boost power converter design optimization. The study provides refreshing design insight of power converters and presents such information as weight annd loss profiles of various semiconductor components and magnetics as a function of the switching frequency.

  4. Parametric algorithms for frequency estimation in PWM converter systems

    Energy Technology Data Exchange (ETDEWEB)

    Lobos, T.; Hejke, I.; Rezmer, J.; Sikorski, T.; Kostyla, P. [Dept. of Electrical Engineering, Wroclaw University of Technology, Wyb. Wyspianskiego 27, 50-370 Wroclaw (Poland)

    2009-11-15

    Proper estimation of voltage parameters has a significant meaning for power converters control systems. One of the measured parameter, directly associated with control process, is frequency of the basic voltage component at the converter output. Unfortunately, power converters generate a wide spectrum of harmonics as well as interharmonics, that makes difficulties in estimation this frequency. Measurement carried out in industrial applications exhibits complex nature of investigated signals often corrupted by resonances or overvoltages phenomena. It entails searching a new digital algorithms for frequency measurement. This work presents algorithm using modification of high-resolution Prony method connected with digital filtering. The investigations was based on simulations and real measured signals recorded in two different commercial PWM converters. Obtained results indicate accuracy of the method as well as its fast response. (author)

  5. Monolithic series-connected gallium arsenide converter development

    Energy Technology Data Exchange (ETDEWEB)

    Spitzer, M.B.; McClelland, R.W.; Dingle, B.D.; Dingle, J.E.; Hill, D.S. (Kopin Corp., Taunton, MA (United States)); Rose, B.H. (Sandia National Labs., Albuquerque, NM (United States))

    1991-01-01

    We report the development of monolithic GaAs photovoltaic devices intended to convert light generated by a laser or other bright source to electricity. The converters described here can provide higher operating voltage than is possible using a single-junction converter, owing to use of a monolithic circuit that forms a planar series-connected string of single-junction sub-cells. This planar monolithic circuit is arranged to deliver the desired voltage and current during operation at the maximum power point. The paper describes two-, six-, and twelve-junction converters intended for illumination by a laser diode with a wavelength of 0.8 {mu}m. Design and characterization data are presented for optical power in the range of 100 mW to 1 W. The best conversion efficiency exceeds 50%. 9 refs., 4 figs., 2 tabs.

  6. Intercooled Turbo-Brayton Power Converter for Spaceflight Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Future NASA space missions require advanced systems to convert thermal energy into electric power. These systems must be reliable, efficient, and lightweight. In...

  7. Concept Study of Foundation Systems for Wave Energy Converters

    DEFF Research Database (Denmark)

    Molina, Salvador Devant; Vaitkunaite, Evelina; Ibsen, Lars Bo

    Analysis of possible foundation solution for Wave Energy Converters (WEC) is presented by investigating and optimizing novel foundation systems recently developed for offshore wind turbines. Gravity based, pile and bucket foundations are innovative foundation systems that are analyzed. Concept...

  8. Power electronic converters and systems frontiers and applications

    CERN Document Server

    Trzynadlowski, Andrzej M

    2016-01-01

    Power electronics is a branch of electrical engineering dealing with conversion and control of electric power using semiconductor power switches. This book provides an overview of modern power electronic converters and systems, and their applications.

  9. High Input Voltage Hall Thruster Discharge Converter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall scope of this Phase I/II effort is the development of a high efficiency 15kW (nominal) Hall thruster discharge converter. In Phase I, Busek Co. Inc. will...

  10. Systematic risk variations (beta convertible debenture brazilian companies

    Directory of Open Access Journals (Sweden)

    Renata Drumond Pinto Coelho Antonino

    2010-01-01

    Full Text Available purpose of this article is to analyze the impact of issuing convertible debentures on the systematic risk of Brazilian companies. Some applied researches in the U.S. capital market (STEIN, 1992; LEWIS et al, 2002; RAI, 2005 indicate that convertible debentures may be used as an alternative financing source when adverse selection problem makes stock issuing unattractive financing source. The analysis of Brazilian companies that issued convertible debentures recorded in the period from 1998 to 2006 and that presented liquidity on the market indicated that variation in beta, on average, is positive. These results are coherent with the signaling hypothesis and with the absence of convertible debenture issuing in 2005 and 2006 on the Brazilian market. They also may be related to the precarious financial situation of issuing companies, observed by the analysis of some financial indicators in year of issue and in two pre- e post-issuing years.

  11. Wavelength converter placement in optical networks with dynamic traffic

    DEFF Research Database (Denmark)

    Buron, Jakob Due; Ruepp, Sarah Renée; Wessing, Henrik;

    2008-01-01

    We evaluate the connection provisioning performance of GMPLS-controlled wavelength routed networks under dynamic traffic load and using three different wavelength converter placement heuristics. Results show that a simple uniform placement heuristic matches the performance of complex heuristics u...

  12. Step-Up DC-DC Power Converter

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a step-up DC-DC power converter which comprises a primary side circuit and a secondary side circuit coupled through a galvanic isolation barrier. The primary side circuit comprises a positive and a negative input terminal for receipt of an input voltage and an input...... being charged from the input voltage and discharged to the output capacitor through the galvanic isolation barrier in accordance with a switch control signal to produce the converter output voltage. The step-up DC-DC power converter comprises an electrical short-circuit connection across the galvanic...... capacitor coupled between the positive and negative input terminals and the secondary side circuit comprises an output capacitor chargeable to a converter output voltage between a first positive electrode and a second negative electrode. A switched energy storage network is configured for alternatingly...

  13. Research on optical biosensor with up-converting phosphor marker

    Institute of Scientific and Technical Information of China (English)

    Yongkai Zhao; Xiangzhao Wang; Lei Zhou; Jing Wang; Lihua Huang; Zhongqiang Yan; Huijie Huang; Ruifu Yang; Lei Liu; Bingqiang Ren

    2006-01-01

    @@ An optical biosensor with up-converting phosphor (UCP) marker is developed for the sensitive rapid immunoassay to the specific biomolecule. UCP can emit visible light when excited by infrared light.

  14. A NEW DESIGN of SIX- PHASE ROTARY CONVERTER ELECTRIC MACHINE

    Directory of Open Access Journals (Sweden)

    K. G. Mohammed

    2012-12-01

    Full Text Available The aim of this research is to design a new ac rotary converter machine to convert the ac single phase voltage to six-phase voltages by using multi stages energy conversion machine. The rotary converter is composed from two main stages and is combined into one frame. These two stages are formed from three main electromagnetic components. The first component represents the input stage that enables the energy from single phase to enter and transformed by the second and third components electro-magnetically to produce six-phase voltages which at the output stage. The programs are created using MATLAB in order to calculate the required dimensions of the converter machine and its parameters for magnetic and electrical circuits.

  15. Three Phase Resonant DC Power Converter for Ion Thrusters Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Our phase 1 study has revealed many significant benefits of a new class of DC-to-DC power converters with performance that cannot be matched by current flight power...

  16. Single Phase Bidirectional PWM Converter for Microgrid System

    Directory of Open Access Journals (Sweden)

    C.Kalavalli

    2013-06-01

    Full Text Available Smart grid is a newly flourishing research area because of its viable applications and expected to address the drawback of existing grid. Microgrids are the part of the Smart grid and they are designed to supply electricity for a small community such as residential areas, universities or industrial sites. Power electronics plays a vital role for connecting the renewable energy sources to Microgrid system. This paper deals the Microgrid connected single phase Bidirectional PWM converter which operates in Rectification and Inverting mode. This converter helps to connect renewable energy sources to loads as well as excess power are given to power grid. Double Loop PID control technique is used for controlling the converter for both modes. The designed Converter is simulated in MATLAB/Simulink software and results are verified using the Hardware.

  17. A Novel High Gain DC-DC Step up Converter

    Directory of Open Access Journals (Sweden)

    M. Al Mamun

    2016-07-01

    Full Text Available High gain dc-dc converters are widely used to maximize the energy harvest for renewable energy systems, for example, photovoltaic systems and fuel cell. Conventional boost converters usually operates at extreme duty cycle to obtain high voltage gain. Operation at extreme duty cycle leads to reverse recovery problem at the switches, high conduction loss, electromagnetic interference etc. This paper proposes a very high gain dc-dc step up converter operating at very low duty cycle (i.e. duty cycle <0.5. The additional advantage of the proposed converter is that a single control signal is used for the switches which reduces the operation complexity. The steady-state theoretical analysis described in this paper is finally verified by simulation results

  18. Effects of cavitation on performance of automotive torque converter

    Directory of Open Access Journals (Sweden)

    Jaewon Ju

    2016-06-01

    Full Text Available Cavitation is a phenomenon whereby vapor bubbles of a flowing liquid are formed in a local region where the pressure of the liquid is below its vapor pressure. It is well known that cavitation in torque converters occurs frequently when a car with an automatic transmission makes an abrupt start. Cavitation is closely related to a performance drop and noise generation at a specific operating condition in a car and a torque converter itself. This study addressed the relation between cavitation and performance in an automotive torque converter in a quantitative and qualitative manner using numerical simulations. The cavitation was calculated at various operating conditions using a commercial flow solver with the homogeneous cavitation model, and the torque converter performance was compared with the experimental data. Numerical results well match to the data and indicate that the cavitation causes significant performance drop, as the pump speed increases or both speed ratio and reference pressure decrease.

  19. Translator program converts computer printout into braille language

    Science.gov (United States)

    Powell, R. A.

    1967-01-01

    Computer program converts print image tape files into six dot Braille cells, enabling a blind computer programmer to monitor and evaluate data generated by his own programs. The Braille output is printed 8 lines per inch.

  20. Polarization converters on double hetero structures containing strained quantum wells

    Science.gov (United States)

    Khalique, U.; van der Tol, J. J. G. M.; Nötzel, R.; Smit, M. K.

    2009-02-01

    The importance of polarization manipulation is increased as optical fiber systems evolve to higher data rates. Photonic integrated circuits should be insensitive to the state of polarization of the light emanating from fibers if they are to be used as detectors, add-drop mutiplexers or cross connects. Either all the integrated components have to be polarization independent or only one polarization direction should be used. For either method, a compact polarization converter is useful. A model is developed for the mode propagation in the waveguide of the slanted side polarization converter based on double hetero structures. The model is extended to include polarization dependent absorption and mismatch. Polarization converters on different double heterostructures (with and without quantum wells) have been designed and are realized by contact optical lithography. The performance of the realized converters is well described with the model.

  1. ENVIRONMENTAL ASPECTS OF GRID CONNECTED POWER ELECTRONIC CONVERTERS CONTROL

    Directory of Open Access Journals (Sweden)

    Tomasz Chmielewski

    2017-03-01

    Full Text Available This paper presents an unconventional view on power electronic converters control as an important factor in environmental protection. Two distinct features that are provided by the control system, namely harmonics elimination and Fault Ride-Through are addressed herein. The paper provides the discussion on how well designed and robust power converter control can influence the environment in a positive way. One of the shortcomings of power converters is emission of current harmonics which results in supply voltage distortion. The appropriate control minimizes the harmonics content which leads to energy losses reduction, especially in power transformers cores. Fault ride-through is an ability of power converter to remain connected and operating in a grid where the fault occurred. It is of paramount importance for integration of large power renewable energy sources. Shutting down e.g. large wind farm would result in engaging the conventional power plants to fill in the energy production gap.

  2. LLCL-Filtered Grid Converter with Improved Stability and Robustness

    DEFF Research Database (Denmark)

    Min, Huang; Wang, Xiongfei; Loh, Poh Chiang

    2016-01-01

    impedance variations, making its design more challenging. To address these concerns, a new parameter design method for LLCL-filter has been formulated in the paper, which when enforced, guarantees robust and stable grid current control regardless of how the grid conditions change. It is thus an enhanced......LLCL-filter has been proven to introduce more filtering at the converter switching frequency, while using smaller passive components. However, like other higher order filters, it introduces resonance to the grid when used with a grid converter. Its stability and robustness are also affected by grid...... method even with no damping added to the grid converter. The method has been applied to the development of an LLCL-filter for testing in the laboratory with a 5-kW, 400-V, and 50-Hz grid converter. The method can also be applied to the lower order LCL-filter with only a slight modification needed....

  3. A Converter for Producing a Hydrogen-Containing Synthesis Gas

    Science.gov (United States)

    Malkov, Yu. P.; Molchanov, O. N.; Britov, B. K.; Fedorov, I. A.

    2016-11-01

    A computational thermodynamic and experimental investigation of the characteristics of a model of a converter for producing a hydrogen-containing synthesis gas from a hydrocarbon fuel (kerosene) with its separate delivery to thermal-oxidative and steam conversions has been carried out. It is shown that the optimum conditions of converter operation correspond to the oxidant excess coefficient in the converter's combustion chamber α > 0.5 at a temperature of the heat-transmitting wall (made from a heat-resistant KhN78T alloy (ÉI 435)) of 1200 K in the case of using a nickel corrugated tape catalyst. The content of hydrogen in the synthesis gas attains in this case 60 vol.%, and there is no release of carbon (soot) in the conversion products as well as no need for water cooling of the converter walls.

  4. A New Asymmetrical Current-fed Converter with Voltage Lifting

    Directory of Open Access Journals (Sweden)

    DELSHAD, M.

    2011-05-01

    Full Text Available This paper presents a new zero voltage switching current-fed DC-DC converter with high voltage gain. In this converter all switches (main and auxiliary turn on under zero voltage switching and turn off under almost zero voltage switching due to snubber capacitor. Furthermore, the voltage spike across the main switch due to leakage inductance of forward transformer is absorbed. The flyback transformer which is connected to the output in series causes to high voltage gain and less voltage stress on the power devices. Considering high efficiency and voltage gain of this converter, it is suitable for green generated systems such as fuel cells or photovoltaic systems. The presented experimental results verify the integrity of the proposed converter.

  5. High Efficiency Power Converter for Low Voltage High Power Applications

    DEFF Research Database (Denmark)

    Nymand, Morten

    , and remote power generation for light towers, camper vans, boats, beacons, and buoys etc. A review of current state-of-the-art is presented. The best performing converters achieve moderately high peak efficiencies at high input voltage and medium power level. However, system dimensioning and cost are often......The topic of this thesis is the design of high efficiency power electronic dc-to-dc converters for high-power, low-input-voltage to high-output-voltage applications. These converters are increasingly required for emerging sustainable energy systems such as fuel cell, battery or photo voltaic based...... determined by the performance at the system worst case operating point which is usually at minimum input voltage and maximum power. Except for the non-regulating V6 converters, all published solutions exhibit a very significant drop in conversion efficiency at minimum input voltage and maximum output power...

  6. MULTILEVEL CONVERTERS FOR MICROWELDING BASED ON M-ARY SYSTEM

    Directory of Open Access Journals (Sweden)

    Zhuikov V.

    2012-12-01

    Full Text Available Multilevel converter constructing and functioning principles are given. Two different approaches to increase efficiency are described. Both decisions are compared with typical applications, so advantages and drawbacks are specified.

  7. Turbo-Brayton Power Converter for Spaceflight Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Future NASA space missions require advanced systems to convert thermal energy into electric power. These systems must be reliable, efficient, and lightweight. In...

  8. Generalised Impedance Converters with only Transconductance Elements and Grounded Capacitors

    Directory of Open Access Journals (Sweden)

    Iqbal A. Khan

    2002-01-01

    capacitors in the realisation of continuous time filters lend to electronic tunability and compatibility to integration in contemporary IC technologies. The generalised impedance converters are also verified using PSPICE-based simulation.

  9. The APA Style Converter: a Web-based interface for converting articles to APA style for publication.

    Science.gov (United States)

    Li, Ping; Cunningham, Krystal

    2005-05-01

    The APA Style Converter is a Web-based tool with which authors may prepare their articles in APA style according to the APA Publication Manual (5th ed.). The Converter provides a user-friendly interface that allows authors to copy and paste text and upload figures through the Web, and it automatically converts all texts, references, and figures to a structured article in APA style. The output is saved in PDF or RTF format, ready for either electronic submission or hardcopy printing.

  10. Direct energy converter controllers for switched reluctance motor operation

    OpenAIRE

    Goodman, Andrew Simon

    2007-01-01

    There is increasing demand for simple motor drives offering high reliability and fault tolerance in applications such as the aerospace actuator industry, with the development of `more electric aircraft'. This thesis presents a motor drive employing a switched reluctance motor, the novel single sided matrix converter, and a novel double band hysteresis based control scheme for control of the converter, implemented using a field programmable gate array (FPGA). The single sided matrix co...

  11. Power electronic converters PWM strategies and current control techniques

    CERN Document Server

    Monmasson, Eric

    2013-01-01

    A voltage converter changes the voltage of an electrical power source and is usually combined with other components to create a power supply. This title is devoted to the control of static converters, which deals with pulse-width modulation (PWM) techniques, and also discusses methods for current control. Various application cases are treated. The book is ideal for professionals in power engineering, power electronics, and electric drives industries, as well as practicing engineers, university professors, postdoctoral fellows, and graduate students.

  12. Integrated magnetics design for HF-link power converters

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2005-01-01

    This paper deals with the design of integrated magnetics for HF-link converters, where the integrated magnetic components do not necessarily belong to the same voltage loop. Depending on the specific HF-link converter topology, the proposed integrated magnetics can either alleviate the derivation...... of independent auxiliary supply voltages from the main transformer or integrate other magnetic structures, thus saving board space and cutting costs....

  13. Experimental Study on the Langlee Wave Energy Converter

    DEFF Research Database (Denmark)

    Lavelle, John; Kofoed, Jens Peter

    This report concerns the experimental study of the 1:20 scale model of the Langlee Wave Energy Converter (WEC) carried out at Aalborg University’s wave basin during the summer of 2010.......This report concerns the experimental study of the 1:20 scale model of the Langlee Wave Energy Converter (WEC) carried out at Aalborg University’s wave basin during the summer of 2010....

  14. Integrated magnetics design for HF-link power converters

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.; Andersen, Michael A.E.

    2005-07-01

    This paper deals with the design of integrated magnetics for HF-link converters, where the two integrated magnetic components on the same core do not necessarily belong to the same voltage loop. Depending on the specific HF-link converter topology, the proposed integrated magnetics can either alleviate the derivation of independent auxiliary supply voltages from the main transformer or integrate other magnetic structures, thus saving board space and cutting costs. (au)

  15. Sealing and anti-corrosive action of tannin rust converters

    Energy Technology Data Exchange (ETDEWEB)

    Gust, J.; Bobrowicz, J. (Building Research Inst., Warsaw (Poland))

    1993-01-01

    A possibility of the application of mercury porosimetry in the investigation on porosity in corrosion products of the carbon steel along with the degree of sealing by the use of tannin rust converters is presented. The effect of the atmospheric humidity on the rust conversion including the time of that conversion on the degree of rust sealing is discussed. The results of the corrosion investigation of carbon steel covered with a layer of the rust converted with tannin-containing agents are presented.

  16. Wave Dragon Wave Energy Converters Used as Coastal Protection

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Harck; Andersen, Thomas Lykke; Kofoed, Jens Peter

    2011-01-01

    This paper deals with wave energy converters used to reduce the wave height along shorelines. For this study the Wave Dragon wave energy converter is chosen. The wave height reduction from a single device has been evaluated from physical model tests in scale 1:51.8 of the 260 x 150 m, 24 kW/m model...... Spain, to evaluate the potential for reducing wave heights close the shore by means of Wave Dragons....

  17. A Comparative Study between Two Control Strategies for Matrix Converter

    OpenAIRE

    BENDIABDELLAH, A.; BACHIR, G.

    2009-01-01

    The authors compare two control strategies for direct AC-AC matrix converters; namely the Venturini method and the scalar strategy control method. The performance comparison of the two strategies is made under unbalanced distorted torque, rotor speed and stator current operation. The simulation of the three-phase matrix converter feeding an induction motor was accomplished by means of the Matlab/Simulink software. This package makes it possible to simulate the dynamic systems in a simple wa...

  18. An improved 4-step commutation method application for matrix converter

    DEFF Research Database (Denmark)

    Guo, Yu; Guo, Yougui; Deng, Wenlang

    2014-01-01

    A novel four-step commutation method is proposed for matrix converter cell, 3 phase inputs to 1 phase output in this paper, which is obtained on the analysis of published commutation methods for matrix converter. The first and fourth step can be shorter than the second or third one. The discussed...... method here is implemented by programming in VHDL language. Finally, the novel method in this paper is verified by experiments....

  19. Conception, modeling, and control of a convertible mini-drone

    OpenAIRE

    Phung, Duc Kien

    2015-01-01

    There is a growing interest to design convertible aerial vehicles that can hover like helicopters and fly forward efficiently like airplanes. This thesis is devoted to the conception, modeling, and control of such a convertible mini-UAV (Unmanned Aerial Vehicle). The main contributions of this work are threefold. Firstly, we design a novel UAV structure by adding to each side of a quadrotor one wing that can rotate around an axis belonging to the propellers' plane. Our prototype has many adva...

  20. Hybrid battery with bi-directional DC/DC converter

    Directory of Open Access Journals (Sweden)

    DUDRIK Jaroslav

    2010-05-01

    Full Text Available Bi-directional buck-boost DC/DC converterfor hybrid battery is described in this paper. The firstpart of the paper is aimed at concept of hybrid battery;main advance compared to conventional accumulatoris explained there. Control circuit with UC3637 andpower circuit of the converter are described in thesecond part of the paper. Experimental results frommeasuring of converter are mentioned in the last part.