Sample records for steven passmore dc
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2012-05-10
... Number: 12-014. Applicant: California Institute of Technology, Pasadena, CA 91125. Instrument: Nova Nano... DEPARTMENT OF COMMERCE International Trade Administration Stevens Institute of Technology, et al... Constitution Avenue NW, Washington, DC Docket Number: 12-008. Applicant: Stevens Institute of Technology...
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... after blisters form If you have Stevens-Johnson syndrome, several days before the rash develops you may experience: Fever Sore mouth and throat Fatigue Cough Burning eyes When to see a doctor Stevens-Johnson ...
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2012 ARPA-E Energy Innovation Summit: Fireside Chat with Steven Chu and Bill Gates
Energy Technology Data Exchange (ETDEWEB)
Chu, Steven; Gates, Bill; Podesta, John
2012-02-28
The third annual ARPA-E Energy Innovation Summit was held in Washington D.C. in February, 2012. The event brought together key players from across the energy ecosystem - researchers, entrepreneurs, investors, corporate executives, and government officials - to share ideas for developing and deploying the next generation of energy technologies. This video captures a session called Fireside Chat that featured Steven Chu, the Secretary of Energy, and Bill Gates, Chairman of Microsoft Corporation. The session is moderated by John Podesta, Chair of the Center for American Progress. Energy Secretary Steven Chu and Microsoft Founder and Chairman Bill Gates exchanged ideas about how small businesses and innovators can overcome the challenges that face many startups.
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James Stevens / James Stevens ; interv. Tilman Baumgärtel
Stevens, James
2006-01-01
Inglise disainerist James Stevensist (sünd. 1962) ja tema tegevusest. J. Stevens 2000. a. Amsterdamis tehtud intervjuus koos Jon Bainsi ja Kim Bulliga 1995. a. Londonis avatud Interneti-agentuurist Obsolete, 1996-2000 tegutsenud Interneti-kohvikust Backspace, mittekommertsiaalse juhtmeteta nerworki Consume.net rajamisest Londonis
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Stevens-Johnson syndrome after radiotherapy
International Nuclear Information System (INIS)
Howell, W.R.; Knight, A.L.; Scruggs, H.J.
1990-01-01
We have reported a case of classic Stevens-Johnson syndrome in association with treatment using a cobalt radiation therapy unit. Previous reports of such an association have been extremely rare. At the time of the reaction, the patient's only medications were methyldopa and trichlormethiazide. Other drugs in the thiazide class have been associated with such a reaction. We feel this is an unlikely association in our patient, however, because she had been on trichlormethiazide for a number of years. This report suggests the role of radiotherapy as a rare cause of Stevens-Johnson syndrome. 14 references
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Steven Spielberg hädas Peeter Paaniga / Timo Diener
Diener, Timo
2004-01-01
Steven Spielbergi raskused J.M. Barrie "Peeter Paani" ekraniseerimisel, tulemuseks mängufilm "Hook" : Ameerika Ühendriigid 1991. Järgneb 16. aug. 2004, lk. 38 pealkirja all "Rahulolematu Steven Spielberg"
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Cefepime Associated With Phenytoin Induced Stevens-Johnson Syndrome.
Marco-Del Río, José; Domingo-Chiva, Esther; Cuesta-Montero, Pablo; Valladolid-Walsh, Ana; García-Martínez, Eva María
We describe a recent case of Stevens-Johnson Syndrome. A 49-year-old man was admitted to the Intensive Care Unit of an Anaesthesia and Resuscitation Department because of a Fournier gangrene that derived in a sepsis, ventilator-associated pneumonia, and renal failure. He was under treatment with cefepime and suffered a generalized status epilepticus, so started treatment with phenytoin. The next day he developed a "maculous cutaneous eruption in trunk and lower limbs" compatible with a Stevens-Johnson Syndrome. Stevens-Johnson Syndrome is a very severe and potentially fatal multiorganic disease, especially when present in critically ill patients, with a strong drug-related etiology, especially with antiepileptic drugs.
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Pinkerton's Creator: Steven Kellogg.
Brodie, Carolyn S.
2002-01-01
Describes the life of Steven Kellogg, a children's book illustrator and writer. Includes extension ideas for school library media center activities related to his works and presents a selected annotated bibliography in chronological order, videos, and biographical information. (LRW)
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Co-amoxiclav-induced Stevens Johnson Syndrome in a child ...
African Journals Online (AJOL)
Stevens-Johnson Syndrome is an uncommon life threatening disease generally induced by drugs. Antibiotics, mainly sulphonamides, are the most involved drugs in Stevens-Johnson Syndrome in children. Co-amoxiclav is a well tolerated antibiotic. It has never been reported to cause, lonely this syndrome in children.
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2009-01-01
Steven Weinberg visiting the ATLAS cavern accompanied by Peter JenniIt was no surprise that the CERN audience arrived early in the Globe of Science and Innovation for the colloquium on 7 July. Nobel laureate Steven Weinberg is one of the major contributors to the Standard Model of particle physics. He received the Nobel Prize for Physics in 1979 for his work on the unified theory of the electromagnetic and weak interactions, one of the essential pillars of the Standard Model. After lunch at CERN and a visit to ATLAS, Weinberg gave a colloquium on "The Quantum Theory of Fields: Effective or Fundamental" to a packed audience. In his talk, he looked at how the use of quantum field theory in particle physics has fluctuated in popularity since Paul Dirac first introduced the approach to describe the interaction of particles with electromagnetic fields in the late 1920s. In particular, he posed the question: Is quantum field theory fundamental or does it a...
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Steven Vogel was an eminent American biophysicist. He made ...
Indian Academy of Sciences (India)
Keywords. Steven Vogel, biomechanics, Péclet number, diffusion, advection, transport. Abstract. Steven Vogel was a pinoneer in applying principles of mechanics to diverse living systems. This article first provides a brief overview of his career. It then reviews the concepts of P´eclet number and Reynolds number which are ...
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Magnuson-Stevens Fishery Conservation Act
National Oceanic and Atmospheric Administration, Department of Commerce — The Magnuson-Stevens Fishery Conservation and Management Act (MSA) is the primary law governing marine fisheries management in U.S. federal waters. It has since been...
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Indian Academy of Sciences (India)
IAS Admin
duced in this issue. Steven Vogel was an eminent American biophysicist. ... as unusual and remarkable as his own work. He pre- .... called Reynolds stress, after the scientist who taught us to think in this ... PES Institute of Technology. Campus.
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Mycoplasma pneumoniae and atypical Stevens-Johnson syndrome: a case series.
Ravin, Karen A; Rappaport, Lara D; Zuckerbraun, Noel S; Wadowsky, Robert M; Wald, Ellen R; Michaels, Marian M
2007-04-01
Mycoplasma pneumoniae is a common cause of community-acquired respiratory illness in the adolescent population. Stevens-Johnson syndrome is an extrapulmonary manifestation that has been associated with M. pneumoniae infections. Three adolescent males presented within a 1-month period with M. pneumoniae respiratory illnesses and severe mucositis but without the classic rash typical of Stevens-Johnson. Diagnosis was facilitated by the use of a polymerase chain reaction-based assay. This case series highlights the potential for M. pneumoniae-associated Stevens-Johnson syndrome to occur without rash and supports the use of polymerase chain reaction for early diagnosis.
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Steven Hawking with Robert Aymar
Maximilien Brice
2006-01-01
Steven Hawking is seen meeting with CERN's Director-General, Robert Aymar. Hawking visited CERN between 24 September and 1 October 2006. During his stay he gave two lectures and toured the LHC, which may provide insights into Hawking's most famous area of study, black holes.
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Stevens-Johnson syndrome associated with antimicrobial agent
Directory of Open Access Journals (Sweden)
Ivo Cavalcanti Pita Neto
2008-01-01
Full Text Available Among the severe reactions to medications, immune-mediated Mucocutaneous Disorders are widely represented. Steven-Johnson’s syndrome, or great multiform erythema, appears as a systemic disturbance, involving the skin and mucous membranes, and is related to several factors, such as, viral or bacterial infections and particularly the administration of medicines, in general painkillers and antibiotics. The objective of this article is report the onset of ulcerative vesicle –blister lesions in the regions of the lips, gums, tongue and genital mucosa membrane in a 26 year-old patient, a leukoderm man, being treated with sulfamethoxazole trimethoprim for a respiratory infection, after being diagnosed as having the Steven-Johnson syndrome. SSJ1 558187121279.
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HLA-B Sequencing in Patients with Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis
2017-03-03
Stevens -Johnson Syndrome and Toxic Epidermal Necrolysis Brittany L. Lenz, MD, Andrew T. Patterson, MD, Amanda J . Laska, MD, Patrick J . Brown, MD, and...59 MDW/SGVU SUBJECT: Professional Presentation Approval 8 DEC 2016 1. Your paper, entitled HLA-B Sequencing in Patients with Stevens -Johnson...PATIENTS WITH STEVENS -JOHNSON SYNDROME AND TOXIC EPIDERMAL NECROL YSIS 2. FUNDING RECEIVED FOR THIS STUDY? DYES rgj NO FUNDING SOURCE: I I 3. IS THIS
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Tables of Products of Tensor Operators and Stevens Operators
DEFF Research Database (Denmark)
Lindgård, Per-Anker
1975-01-01
Numerical tables of products of tensor (Racah) operators, Rl,m(J), and Stevens operators Olm(J), working within a J-multiplet are given as a function of X=J(J+1). Examples of the use of the tables, such as the calculation of commutation relations and thermal averages are given.......Numerical tables of products of tensor (Racah) operators, Rl,m(J), and Stevens operators Olm(J), working within a J-multiplet are given as a function of X=J(J+1). Examples of the use of the tables, such as the calculation of commutation relations and thermal averages are given....
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T. Rapatsikou on Bart and Ragg’s Wallace Stevens
Directory of Open Access Journals (Sweden)
2009-07-01
Full Text Available Eeckhout, Bart and Edward Ragg, eds. Wallace Stevens Across the Atlantic (Basingstoke and New York: Palgrave Macmillan, 2008. Pp. xvii + 246. ISBN 978-0-230-53584-8.Bart Eeckhout and Edward Ragg’s edited collection of essays entitled Wallace Stevens Across the Atlantic is a diverse, well-informed and excellently conceptualized volume offering fresh insights into Wallace Stevens’ poetry. This book can serve as a good introduction to Wallace Stevens’ oeuvre for the general reader, university s...
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Two autographs: Cecile Dewitt and Robert Hawking (for Steven Hawking)
Gaina, Alex
2007-12-01
Two autographs given to author by professor Cecile Dewitt and Robert Hawking (the son of Steven Hawking for his father) in 1987 during the Quantum Gravity Seminar in Moscow are presented. The first was given during a visit to Physical Institute of the Academy of sciences of the USSR, where a seminar held in the Theoretical department. the second was given during a lunch with Steven Hawking, Andrei Linde and Robert Hawking at the 2-nd floor of the Conference floor.
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Martin, L; Hazouard, E; Michalak-Provost, S; Maurage, C; Machet, L
2001-09-01
Acute bronchial mucosal sloughing related to Toxic Epidermal Necrolysis (Lyell syndrome) is widely reported in literature. On the contrary severe respiratory involvement is rare in post-infectious or toxic Epitheliolysis (Stevens-Johnson syndrome). There is no well-known predictive sign of bronchial epithelium involvement. An 18-year-old patient was admitted for Stevens-Johnson syndrome related to sulfasalazine (salazosulfapyridine). There were no respiratory signs. An acute respiratory failure occurred 36 hours after from admission due to an obstructive and desquamative necrosis of the tracheobronchial epithelium. We purpose that a fiberoptic laryngoscopy should be performed even in non-dyspneic patients suffering from Stevens-Johnson syndrome if hypersecretion is present. Fiberoptic bronchoscopy can be helpful in these cases.
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Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis ...
African Journals Online (AJOL)
REVIEW. Introduction. Stevens-Johnson syndrome (SJS) and toxic epidermal ... that affect the skin and mucous membranes. ... Open Access article distributed under the terms of the .... pathogenic components are removed from plasma. The.
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Stevens Johnsons syndrom og toksisk epidermal nekrolyse
DEFF Research Database (Denmark)
Kaur-Knudsen, Diljit; Zachariae, Claus; Thomsen, Simon Francis
2013-01-01
Stevens-Johnson syndrome and toxic epidermal necrolysis are acute mucocutaneous diseases primarily due to drug intake. The diseases are characterised by the separation of epidermis from dermis which can be life-threatening. Mortality is often caused by sepsis and multiple organ failure. The most...
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Steven Moffat and Sue Vertue visits CERN
Caraban Gonzalez, Noemi
2016-01-01
Steven William Moffat, OBE is a Scottish television writer and producer, known for his work as showrunner, writer and producer of the British television series Doctor Who and Sherlock. Susan "Sue" Nicola Vertue is an English television producer, mainly of comedy shows, including Mr. Bean and Coupling.
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Stevens-Johnson syndrome in a patient with rheumatoid arthritis during long-term etanercept therapy.
Owczarczyk-Saczonek, Agnieszka; Zdanowska, Natalia; Znajewska-Pander, Aleksandra; Placek, Waldemar
2016-03-31
Etanercept and other anti-TNF-alpha agents have been indicated as a therapeutic option in severe drug reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis. Etanercept has been shown to quickly reduce the detachment of the epidermis and shorten healing time. Cases of etanercept-induced severe adverse drug reactions were also described. A 27-year-old woman with a 4-year history of etanercept and sulfasalazine treatment for rheumatoid arthritis was admitted with Stevens-Johnson syndrome. The patient received one dose of an OTC drug containing acetaminophen, phenylephrine and pheniramine two days prior to developing fist mucocutaneous symptoms. The most probable causative agent was paracetamol. Throughout the successful routine therapy of Stevens-Johnson syndrome etanercept therapy was continued. Sulfosalazin administration was stopped and administered again after recovery with no recurrence of the skin and mucosal symptoms. This case indicates that there is no justification for discontinuation of long-term anti-TNF-alpha treatment in patients who develop Stevens- Johnson syndrome / toxic epidermal necrolysis.
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Born To Draw: A Profile of Steven Kellogg.
Elleman, Barbara
2001-01-01
Presents a profile of Steven Kellogg, an illustrator of children's books. Gives an overview of his career discussing how he got started and broke into the scene. Describes some of the books he has illustrated and relates his experiences with those books. (SG)
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DC electric springs with DC/DC converters
DEFF Research Database (Denmark)
Wang, Qingsong; Cheng, Ming; Jiang, Yunlei
2016-01-01
The concept of DC electric spring (DCES) was recently proposed to solve the stability issue caused by integrating intermittent renewable energy sources (RESs) to DC microgrids. In this paper, a new topology of DCES is proposed based on DC/DC converters. The proposed DCES consists of a bi-directio......The concept of DC electric spring (DCES) was recently proposed to solve the stability issue caused by integrating intermittent renewable energy sources (RESs) to DC microgrids. In this paper, a new topology of DCES is proposed based on DC/DC converters. The proposed DCES consists of a bi...... and/or constant discharging for batteries is adopted and four operating modes are analyzed as charging-positive, charging-negative, discharging-positive and discharging-negative modes. An additional mechanism for fast charging or fast discharging is also designed to secure normal operation...... of batteries. With the proposed DCES, the power fluctuations due to intermittent RESs can be passed to non-critical loads (NCLs) and batteries while power on critical loads (CLs) is kept stable. This is possibly the first attempt to design a DCES with only DC/DC converters. The performances of the proposed...
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Musical Metaphors in the Poetry of Wallace Stevens
Directory of Open Access Journals (Sweden)
Victor Kennedy
2016-06-01
Full Text Available Wallace Stevens’s “The Man with the Blue Guitar” (1937 is widely recognized as one of the most important and influential poems of the 20th century. Inspired by Picasso’s painting The Old Guitarist, the poem in turn inspired Michael Tippett’s sonata for solo guitar, “The Blue Guitar” (Tippett 1983 and David Hockney’s The Blue Guitar: Etchings by David Hockney who was inspired by Wallace Stevens who was inspired by Pablo Picasso (Hockney and Stevens 1977. Central to “The Man with the Blue Guitar,” the metaphor of the musical instrument as a transformational symbol of the imagination is common in Stevens’s poems. The structure of “The Man with the Blue Guitar,” according to J. Hillis Miller, is the structure of stream-of-consciousness. Stevens’s poem creates what has been called “the deconstructed moment in modern poetry,” “an attempt to project a spatialized time that can be viewed from the privileged position of a timeless, static moment capable of encompassing a life at a glance” (Jackson 1982. This consciousness, which Derrida refers to as the “trace,” Stevens calls “the evasive movement of language.” The trace is the perception of the absence of meaning after the word or perception has passed, the glimpse of a hidden meaning that immediately vanishes. Stevens’s poem influenced not only other poets, artists and composers; references to and echoes of his ideas and techniques can be seen in popular music and culture well into the 21st century.
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2010-05-05
... Management Act (Magnuson-Stevens Act) Provisions; Fishing Vessel, Fishing Facility and Individual Fishing... Fisheries Finance Program (FFP or the Program) provides long-term financing to the commercial fishing and...) lending program, 16 U.S.C. 1855(i)(1). The Magnuson-Stevens Fishery Conservation and Management...
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Síndrome de Stevens-Johnson: Presentación de 1 caso
Directory of Open Access Journals (Sweden)
Luisa María Pacheco Álvarez
2001-12-01
Full Text Available El síndrome de Stevens-Johnson, es una enfermedad inflamatoria aguda, originada por una hipersensibilidad, que incluye la piel y las membranas mucosas; en una forma mayor pone en peligro la vida del paciente. Puede ser inducida por muchos factores precipitantes, desde los medicamentos hasta una infección. La afección se caracteriza por una súbita erupción morfológicamente variable, acompañada de estomatitis y oftalmia. En este trabajo se presenta un niño de 8 años de edad, con la entidad clínica en forma muy severa, el síndrome de Stevens-Johnson, que involucra manifestaciones cutáneas, oculares y de la mucosa oral, acompañada de otras complicaciones graves, por lo que requirió terapéutica en cuidados intensivos, y se logró una evolución satisfactoria del paciente.Stevens-Johnson syndrome is an acute inflammatory disease caused by a hypersensibility that includes the skin and the mucous membranes and that in a severe form endangers the patient’s life. It may be induced by many precipitating factors, from drugs to infection. The affection is characterized by a sudden morphologically variable rash, accompanied with stomatitis and ophthalmia. An 8-year-old boy suffering from this clinical entity in a very severe form, Stevens-Johnson syndrome, with skin , ocular and oral mucosa manifestations and with other serious complications, is presented in this paper. He had to be treated at the ICU and a satisfactory evolution was attained.
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Luo, Fang Lin
2003-01-01
DC/DC conversion techniques have undergone rapid development in recent decades. With the pioneering work of these authors, DC/DC converters have now moved into their sixth generation. This book offers a concise, practical presentation of DC/DC converters, summarizing the spectrum of conversion tecnologies and presentingmany new ideas and more than 100 new topologies. Nowhere else in the literature are DC/DC converters so logically sorted and systematically introduced, and nowhere else can readers find detailed information on prototype topologies that represent a major contribution to modern power engineering. More than 320 figures, 60 tables, and 500 formulae facilitate understand and provide precise data.
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Fatal nevirapine-induced Stevens- Johnson syndrome with HIV ...
African Journals Online (AJOL)
2014-06-01
Jun 1, 2014 ... of Stevens-Johnson syndrome highlights the dilemmas and complications that may arise when prescribing multiple medications in HIV-associated ... HIV enters the central nervous system early in the course of HIV ... Affected individuals with SJS/TEN are genetically predisposed to developing severe ...
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Genetics Home Reference: Stevens-Johnson syndrome/toxic epidermal necrolysis
... Hung SI. Recent advances in the genetics and immunology of Stevens-Johnson syndrome and toxic epidermal necrosis. ... 2012 May 29. Citation on PubMed or Free article on PubMed Central More from Genetics Home Reference ...
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A Unidirectional DC-DC Autotransformer for DC Grid Application
Directory of Open Access Journals (Sweden)
Meng Zhou
2018-03-01
Full Text Available Conventional unidirectional DC-DC converters for DC grid application employ DC-AC-DC two-stage conversion technology and suffer from high converter cost and power loss. To solve these issues, a unidirectional step-up DC-DC autotransformer (UUDAT and a unidirectional step-down DC-DC autotransformer (DUDAT are studied. The UUDAT and DUDAT are composed of a series connection of diode bridges and voltage source converters. Topologies of UUDAT and DUDAT are detailed. The harmonic and un-controllability issues are discussed. Control and possible application scenarios for UUDAT and DUDAT are depicted. DC fault isolation mechanism and the methods of dimensioning the voltage and power ratings of the components in UUDAT and DUDAT are studied. Extensive simulations on power system level and experiments on a UUDAT and DUDAT prototype verified their technical feasibility.
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Risk of nevirapine-associated Stevens-Johnson syndrome among ...
African Journals Online (AJOL)
Background. Stevens-Johnson syndrome (SJS) is an acute life-threatening condition often elicited by drugs. The government's indecisiveness in deciding to stop the use of nevirapine (NVP) in HIV-infected pregnant women owing to the increase of SJS among this population group in South Africa prompted this investigation ...
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Gamification is broken. An interview with Steven Poole
Directory of Open Access Journals (Sweden)
Marco Benoit Carbone
2012-05-01
Full Text Available Steven Poole is the author of Trigger Happy (2000. New York, NY: Arcade Publish, Unspeak (2006. New York, NY: Grove Press, and You Aren’t What You Eat (2012. In press. He has written extensively on books, culture, and videogames for The Guardian and other publications.
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2012-11-21
... Railway Service Corporation, Steven C. Hawkins and Cheryl R. Hawkins--Continuance in Control Exemption--Aiken Railway Company, LLC Western Carolina Railway Service Corporation (WCRS) and Steven C. Hawkins and Cheryl R. Hawkins (the Hawkins) (collectively, Applicants) have filed a verified notice of exemption...
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Evaluation of conjunctival bacterial flora in patients with Stevens-Johnson Syndrome
Directory of Open Access Journals (Sweden)
Luciana Frizon
2014-03-01
Full Text Available OBJECTIVE: To determine the conjunctival bacterial flora present in patients with Stevens-Johnson syndrome. METHODS: A prospective study of the conjunctival bacterial flora was performed in 41 eyes of 22 patients with Stevens-Johnson syndrome. The information gathered included the patient's sex and age, the duration of disease, the cause of Stevens-Johnson syndrome, and treatments. Scrapings of the inferior conjunctival fornix were performed in both eyes. Fourteen days before scraping, the patients were asked to interrupt all topical medication and start using 0.5% nonpreserved methylcellulose. The microbiological evaluation included microorganism identification and determination of antibiotic sensitivity. RESULTS: Of 22 patients (41 eyes, 14 (64% were females, and eight (36% were males. The mean age was 33.2 years, and the mean duration of disease was 15.6 years. Visual acuity ranged from light perception to 20/25 (1.57 logMar. The treatment received by most patients consisted of tear substitutes, topical antibiotics, and contact lenses. Bacterial identification was positive in 39 eyes (95% and negative in two eyes (5%. Gram-positive cocci accounted for 55.5% of the microorganisms, whereas gram-positive bacilli and gram-negative bacilli accounted for 19% and 25.5%, respectively. Half of the patients (54% had multiple bacterial species in their flora, and only one bacterial species was identified in the other half. Resistant bacteria were isolated from four eyes. The antibiotic sensitivity results for the Streptococcus group showed the lowest sensitivity and the highest microbial resistance identified. CONCLUSION: Patients with Stevens-Johnson syndrome have a diverse conjunctival flora that includes many pathogenic species.
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Award for Distinguished Scientific Contributions: Steven F. Maier
American Psychologist, 2009
2009-01-01
Steven F. Maier, winner of the Award for Distinguished Scientific Contributions, is cited for his work in the fields of learned helplessness; cytokines, depressed mood, and cognitive interference; and the brain structures that produce and counteract learned helplessness. In addition to the citation, a biography and selected bibliography of Maier's…
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International Nuclear Information System (INIS)
Kim, M.J.; Lee, K.Y.
1996-01-01
About one third of children with Stevens-Johnson syndrome have pulmonary involvement. As a consequence of airway epithelial injury, bronchiolitis obliterans can occur in these patients. Two cases of Stevens-Johnson syndrome-associated bronchiolitis obliterans in children were diagnosed and followed by high resolution CT without open lung biopsy. Serial changes of high resolution CT features of bronchiolitis obliterans are discussed and the literature is reviewed. (orig.)
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Holokaust Steven Spielbergi pilgu läbi / Andres Laasik
Laasik, Andres, 1960-2016
2000-01-01
Oscari võitnud dokumentaalfilm "Need viimased päevad" ("The Last Days") : režissöör James Moll : Tootja Steven Spielbergi loodud Survivors of the Shoah Visual History Foundation : Ameerika Ühendriigid 1999. Filmi esitlusest Eesti Vabariigi Välisministeeriumis
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Justice John Paul Stevens and the Erotic Boomerang.
Lieberman, Marc
Justice John Paul Stevens of the United States Supreme Court has ruled on obscenity cases in seven instances since his appointment. His rulings reveal that he regards obscenity as a nuisance rather than as a danger threatening to undermine the nation's morality, that he supports a nationwide standard to adjudicate obscenity cases, and that he…
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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 s......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...
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Concurrence of Stevens-Johnson Syndrome and Bilateral Parotitis after Minocycline Therapy
Directory of Open Access Journals (Sweden)
Jimi Yoon
2010-06-01
Full Text Available Minocycline is an antibiotic of tetracycline derivatives that is commonly used in the treatment of moderate to severe acne vulgaris. It has been reported to cause rare adverse events from mild cutaneous eruption to severe forms including drug-induced lupus, serum sickness-like reaction, and hypersensitivity reactions, etc. The risks of adverse events attributed to minocycline have not been ascertained reliably and there are concerns about the safety of minocycline which could possibly result in life-threatening events such as the Stevens-Johnson syndrome. Here we demonstrate an unusual case of Stevens-Johnson syndrome in conjunction with bilateral parotitis after the intake of minocycline in a Korean boy suggesting discreet use of the drug.
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DEFF Research Database (Denmark)
Forouzesh, Mojtaba; Siwakoti, Yam P.; Gorji, Saman A.
2017-01-01
on the general law and framework of the development of next-generation step-up dc-dc converters, this paper aims to comprehensively review and classify various step-up dc-dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage......DC-DC converters with voltage boost capability are widely used in a large number of power conversion applications, from fraction-of-volt to tens of thousands of volts at power levels from milliwatts to megawatts. The literature has reported on various voltage-boosting techniques, in which......-boosting techniques and associated converters are discussed in detail. Finally, broad applications of dc-dc converters are presented and summarized with comparative study of different voltage-boosting techniques....
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A resonant dc-dc power converter assembly
Madsen, Mickey Pierre
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 fo...
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DEFF Research Database (Denmark)
Forouzesh, Mojtaba; Siwakoti, Yam P.; Gorji, Saman A.
2017-01-01
on the general law and framework of the development of next-generation step-up dc-dc converters, this paper aims to comprehensively review and classify various step-up dc-dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage...
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Steven Vogel was an eminent American biophysicist. He made ...
Indian Academy of Sciences (India)
2016-08-26
Aug 26, 2016 ... Steven Vogel was a pinoneer in applying principles of mechanics to diverse living systems. This article first provides a brief overview of his career. It then reviews the concepts of P´eclet number and Reynolds number which are helpful in appreciating the Classics article by Vogel reproduced in this issue.
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International Nuclear Information System (INIS)
Kiser, S.C.; Chenot, D.W.
1991-01-01
Waste-water disposal is a major concern of the petroleum business, especially because of complications associated with many produced-water surface-impoundment percolation facilities. In the San Joaquin Valley, California, the current environmental regulations protecting the potentially usable groundwaters are stringent. the Stevens has significant potential as a disposal zone that may offer considerable capacity when the project is designed using proper geologic and engineering studies. The Stevens sands are well known for their oil-producing capabilities, however, not much has been published regarding its suitability as a zone for deep well injection. Conditions that make the Stevens potentially suitable include (1) adequate confinement providing geologic separation from the groundwater sources in the basin, (2) storage capacity, and (3) large areal extent. Because the search for acceptable disposal options is becoming critical, the current class II disposal options is becoming critical, the current class II disposal activities in the Stevens sands were reviewed and the areas offering the greatest future potential were identified. The authors then discuss class II disposal projects in Stevens sands in the West Bellevue and Midway Sunset oil fields and estimate the ultimate basin-wide disposal capacity of the Stevens
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Stevens-Johnson Syndrome After Armodafinil Use.
Holfinger, Steven; Roy, Asim; Schmidt, Markus
2018-05-15
We present the case of a 21-year-old woman in whom Stevens-Johnson syndrome (SJS) developed after initiation of armodafinil. Although this rare and life-threatening reaction is listed on armodafinil's label, no cases have been reported in the literature. This case, in addition to an update of the drug's label after post-marketing research, both support the link between armodafinil and SJS. Providers should maintain a high clinical suspicion for SJS when starting therapy to minimize associated morbidity and mortality by discontinuing armodafinil at the onset of first symptoms. © 2018 American Academy of Sleep Medicine.
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2010-05-04
... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10... amends Sec. 39.13 by adding the following new AD: 2010-09-12 McDonnell Douglas Corporation: Amendment 39... to McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC-10A...
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Steven MacCall: Winner of LJ's 2010 Teaching Award
Berry, John N., III
2010-01-01
This article profiles Steven L. MacCall, winner of "Library Journal's" 2010 Teaching Award. An associate professor at the School of Library and Information Studies (SLIS) at the University of Alabama, Tuscaloosa, MacCall was nominated by Kathie Popadin, known as "Kpop" to the members of her cohort in the online MLIS program at SLIS. Sixteen of…
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DC Home Appliances for DC Distribution System
Directory of Open Access Journals (Sweden)
MUHAMMAD KAMRAN
2017-10-01
Full Text Available This paper strengthens the idea of DC distribution system for DC microgrid consisting of a building of 50 apartments. Since the war of currents AC system has been dominant because of the paucity of research in the protection of the DC system. Now with the advance research in power electronics material and components, generation of electricity is inherently DC as by solar PV, fuel cell and thermoelectric generator that eliminates the rectification process. Transformers are replaced by the power electronics buck-boost converters. DC circuit breakers have solved the protection problems for both DC transmission and distribution system. In this paper 308V DC microgrid is proposed and home appliances (DC internal are modified to operate on 48V DC from DC distribution line. Instead of using universal and induction motors in rotary appliances, BLDC (Brushless DC motors are proposed that are highly efficient with minimum electro-mechanical and no commutation losses. Proposed DC system reduces the power conversion stages, hence diminishes the associated power losses and standby losses that boost the overall system efficiency. So in view of all this a conventional AC system can be replaced by a DC system that has many advantages by cost as well as by performance
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Family of multiport bidirectional DC-DC converters
Tao, H.; Kotsopoulos, A.; Duarte, J.L.; Hendrix, M.A.M.
2006-01-01
Multiport DC-DC converters are of potential interest in applications such as generation systems utilising multiple sustainable energy sources. A family of multiport bidirectional DC-DC converters derived from a general topology is presented. The topology shows a combination of DC-link and magnetic
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Soheili, Arash; Tambar, Uttam K
2013-10-04
A formal total synthesis of (±)-amathaspiramide F through a tandem palladium-catalyzed allylic amination/[2,3]-Stevens rearrangement is reported. The unexpected diastereoselectivity of the [2,3]-Stevens rearrangement was controlled by the substitution patterns of an aromatic ring. This discovery represents a new stereocontrolling element for [2,3]-sigmatropic rearrangements in complex molecular settings.
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Design and Testing of Boost Type DC/DC Converter for DC Motor Control Applications
Samman, Faizal Arya; Akil, Yusri Syam; Noor, Nirwan A.
2017-01-01
in The Proceeding of The 2nd International Symposium on Smart Material and Mechatronics 2015 This paper presents the design and testing of a boost type DC/DC converter circuit, which can be used for DC motor control applications. The Boost converter is designed using DC chopper and DC chopper cascade configurations. The experimental setup was made by connecting the boost converter circuit with four types of DC motor, i.e. self-excited DC motor shunt, series, compound and separately exci...
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Comparison of Olive Tipped and Conventional Steven's Cannula for Sub-Tenon Ophthalmic Anesthesia.
Al-Motowa, Saeed; Ahmad, Nauman; Khandekar, Rajiv; Zahoor, Abdul
2016-01-01
To compare the efficacy of the olive tipped (OT) cannula to the conventional Steven's cannula for sub-Tenon block (STB) before cataract surgery. This prospective, randomized, double-masked compared STB delivered in cataract surgery patients with an OT cannula or a conventional Steven's cannula (ST). Outcome variables included the akinesia score and lid movement scores at 5 and 10 min. The patient perception of pain during delivery of the STB and surgery were also compared between groups. Surgeon satisfaction with anesthesia was compared between groups. P <0.05 was statistically significant. There were sixty patients in each group. The age between groups was not statistically different ( P = 0.4). The body mass index was higher in the ST group compared to the OT group ( P < 0.001). The akinesia score at 5 and 10 min did not differ between groups ( P = 0.07 and P = 0.6, respectively). The patient perception of pain during STB and surgery were similar between groups ( P = 0.1 and P = 0.06, respectively). There were six patients with mild chemosis and redness in the OT group and 15 patients in the ST group. An OT cannula is equally effective as the conventional Steven's cannula for delivering STB anesthesia before cataract surgery.
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Five-Level Active-Neutral-Point-Clamped DC/DC Converter for Medium-Voltage DC Grids
DEFF Research Database (Denmark)
Liu, Dong; Deng, Fujin; Chen, Zhe
2017-01-01
This paper proposes a five-level active-neutralpoint- clamped (5L-ANPC) dc/dc converter for applications in medium voltage dc (MVDC) grids. A modulation strategy is proposed for the 5L-ANPC dc/dc converter to generate multilevel voltage waveforms, which can effectively reduce voltage change rate dv...... effectively eliminate high voltage leaps caused by the dead time effect. In addition, a capacitor voltage control strategy is proposed for the 5L-ANPC dc/dc converter to ensure the balanced flying capacitor voltage and desired five-level voltage waveforms. Finally, simulation and experimental studies...
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Control of improved full-bridge three-level DC/DC converter for wind turbines in a DC grid
DEFF Research Database (Denmark)
Deng, Fujin; Chen, Zhe
2013-01-01
transformer in the IFBTL dc/dc converter. A modulation strategy, including two operation modes, is proposed for the IFBTL dc/dc converter. Then, a voltage balancing control strategy is proposed for the IFBTL dc/dc converter. Furthermore, the control of the wind turbine based on the IFBTL dc/dc converter......This paper presents an improved full-bridge three-level (IFBTL) dc/dc converter for a wind turbine in a dc grid by inserting a passive filter into the dc/dc converter to improve the performance of the converter. The passive filter can effectively reduce the voltage stress of the medium frequency...
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Directory of Open Access Journals (Sweden)
M. Akherraz
1997-12-01
Full Text Available This paper presents an in-depth analytical and experimental investigation of an indirect DC-DC converter. The DC-AC conversion is a full bridge based on IGBT power modules, and the AC-DC conversion is done via a high frequency AC link and a first diode bridge. The AC link, which consists of snubbing capacitors and a variable air-gap transformer, is analytically designed to fulfill Zero Voltage commutation requirement. The proposed converter is simulated using PSPICE and a prototype is designed built and tested in the laboratory. PSPICE simulation and experimental results are presented and compared.
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Three-port DC-DC converter with new integrated transformer for DC Distribution Systems
DEFF Research Database (Denmark)
Ouyang, Ziwei; Andersen, Michael A. E.
2014-01-01
A new integrated transformer for three-port dc-dc converter is proposed to overcome the power coupling effect existed in some known multiple inputs dc-dc converters. Orthogonal primary windings arrangement and in series connection of diagonal secondary Windings enables a fully power decoupling...
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Three new DC-to-DC Single-Switch Converters
Directory of Open Access Journals (Sweden)
Barry W. Williams
2017-06-01
Full Text Available This paper presents a new family of three previously unidentified dc-to-dc converters, buck, boost, and buck-boost voltage-transfer-function topologies, which offer advantageous transformer coupling features and low capacitor dc voltage stressing. The three single-switch, single-diode, converters offer the same features as basic dc-to-dc converters, such as the buck function with continuous output current and the boost function with continuous input current. Converter time-domain simulations and experimental results (including transformer coupling support and extol the dc-to-dc converter concepts and analysis presented.
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Are steroids effective in toxic epidermal necrolysis and Stevens-Johnson syndrome?
Directory of Open Access Journals (Sweden)
Rodrigo Meza
2017-06-01
Full Text Available Resumen La necrólisis epidérmica tóxica y el síndrome de Stevens-Johnson son reacciones cutáneas adversas graves a medicamentos e infecciones. Los corticoides se describen como una alternativa terapéutica, sin embargo, su uso es aún controvertido. Utilizando la base de datos Epistemonikos, la cual es mantenida mediante búsquedas en múltiples bases de datos, identificamos cuatro revisiones sistemáticas que en conjunto incluyen once estudios primarios que responden la pregunta de interés. Extrajimos los datos y preparamos una tabla de resumen de los resultados utilizando el método GRADE. Concluimos que no está claro si los corticoides disminuyen la mortalidad o la estadía hospitalaria en la necrólisis epidérmica tóxica y el síndrome de Stevens-Johnson porque la certeza de la evidencia es muy baja.
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Stevens-Johnson syndrome associated with Malarone antimalarial prophylaxis.
Emberger, Michael; Lechner, Arno Michael; Zelger, Bernhard
2003-07-01
To the best of our knowledge, Stevens-Johnson syndrome (SJS) has not been reported previously as an adverse reaction to Malarone, which is a combination of atovaquone and proguanil hydrochloride used for antimalarial prophylaxis and therapy. We describe a 65-year-old patient who had SJS with typical clinical and histopathological findings associated with the use of Malarone prophylaxis for malaria. This report should alert physicians to this severe cutaneous reaction, and Malarone should be added to the list of drugs that can potentially cause SJS.
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2010-10-01
... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10... adding the following new AD: 2010-20-14 McDonnell Douglas Corporation: Amendment 39-16449. Docket No. FAA... the airplanes identified in paragraphs (c)(1) and (c)(2) of this AD. (1) McDonnell Douglas Corporation...
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2010-07-07
...-0672; Directorate Identifier 2010-NM-047-AD] RIN 2120-AA64 Airworthiness Directives; McDonnell Douglas...: McDonnell Douglas Corporation: Docket No. FAA-2010-0672; Directorate Identifier 2010-NM-047-AD. Comments Due... applies to McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-30, DC-10-30F (KDC-10), DC-10...
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2010-02-08
...-0032; Directorate Identifier 2009-NM-213-AD] RIN 2120-AA64 Airworthiness Directives; McDonnell Douglas...: McDonnell Douglas Corporation: Docket No. FAA-2010-0032; Directorate Identifier 2009-NM-213-AD. Comments Due... applies to McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC-10A...
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2010-10-07
... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 8-31, DC-8-32, DC-8-33, DC-8-41, DC-8-42, and... to all of the McDonnell Douglas Corporation airplanes identified above. The existing AD currently... the following new airworthiness directive (AD): 2010-21-03 McDonnell Douglas Corporation: Amendment 39...
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Multi Bus DC-DC Converter in Electric Hybrid Vehicles
Krithika, V.; Subramaniam, C.; Sridharan, R.; Geetha, A.
2018-04-01
This paper is cotncerned with the design, simulation and fabrication of the prototype of a Multi bus DC- DC converter operating from 42V DC and delivering 14V DC and 260V DC. As a result, three DC buses are interconnected through a single power electronic circuitry. Such a requirement is energized in the development of a hybrid electric automobile which uses the technology of fuel cell. This is implemented by using a Bidirectional DC-DC converter configuration which is ideally suitable for multiple outputs with mutual electrical isolation. For the sake of reduced size and cost of step-up transformer, selection of a high frequency switching cycle at 10 KHz was done.
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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...
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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.
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Pediatric Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis Halted by Etanercept.
Gavigan, Geneviève M; Kanigsberg, Nordau D; Ramien, Michele L
2018-02-01
We report a case of an 11-year-old female with Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) overlap, most likely triggered by sulfamethoxazole-trimethoprim, who was treated with the combination of methylprednisolone, cyclosporine, and etanercept. Her condition stabilized and her skin involvement did not progress after the addition of etanercept. To our knowledge, this is the first report of etanercept for pediatric SJS/TEN.
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Early Oscillation Detection for DC/DC Converter Fault Diagnosis
Wang, Bright L.
2011-01-01
The electrical power system of a spacecraft plays a very critical role for space mission success. Such a modern power system may contain numerous hybrid DC/DC converters both inside the power system electronics (PSE) units and onboard most of the flight electronics modules. One of the faulty conditions for DC/DC converter that poses serious threats to mission safety is the random occurrence of oscillation related to inherent instability characteristics of the DC/DC converters and design deficiency of the power systems. To ensure the highest reliability of the power system, oscillations in any form shall be promptly detected during part level testing, system integration tests, flight health monitoring, and on-board fault diagnosis. The popular gain/phase margin analysis method is capable of predicting stability levels of DC/DC converters, but it is limited only to verification of designs and to part-level testing on some of the models. This method has to inject noise signals into the control loop circuitry as required, thus, interrupts the DC/DC converter's normal operation and increases risks of degrading and damaging the flight unit. A novel technique to detect oscillations at early stage for flight hybrid DC/DC converters was developed.
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Superconducting energy stabilizer with charging and discharging DC-DC converters
International Nuclear Information System (INIS)
Kim, S.H.; Kostecki, E.L.; DeWinkel, C.C.
1992-01-01
This patent describes a superconducting energy stabilizer having multiple load connections and employing DC-DC conversion for storing energy in a superconducting inductive energy storage device having a first end and a second end, and for releasing the stored energy from the superconducting inductive energy storage device to a load or loads or to a utility or an industrial electrical distribution system, the superconducting energy stabilizer having multiple load connections and employing DC-DC conversion. It comprises: energy storage cell means for supplying energy to the load, discharging DC-DC converter means for releasing energy from the superconducting inductive energy storage device to the energy storage cell means, the discharging DC-DC converter means having input terminals, output terminals, and a discharging control line means for carrying signals controlling the operation of the discharging DC-DC converter means, one of the input terminals of the discharging DC-DC converter means coupled to the first end of the superconducting energy storage device
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Steven Spielberg: My Primary Purpose in Making "Schindler's List" Was for Education.
Feinberg, Stephen; Totten, Samuel
1995-01-01
Presents an interview with Steven Spielberg on his goals and methods for making "Schindler's List." Maintains that the important lessons of truth and tolerance will help prevent the Holocaust from happening again. Describes cooperative ventures with educational groups to develop instructional materials associated with the film. (CFR)
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dc Arc Fault Effect on Hybrid ac/dc Microgrid
Fatima, Zahra
The advent of distributed energy resources (DER) and reliability and stability problems of the conventional grid system has given rise to the wide spread deployment of microgrids. Microgrids provide many advantages by incorporating renewable energy sources and increasing the reliability of the grid by isolating from the main grid in case of an outage. AC microgrids have been installed all over the world, but dc microgrids have been gaining interest due to the advantages they provide over ac microgrids. However the entire power network backbone is still ac and dc microgrids require expensive converters to connect to the ac power network. As a result hybrid ac/dc microgrids are gaining more attention as it combines the advantages of both ac and dc microgrids such as direct integration of ac and dc systems with minimum number of conversions which increases the efficiency by reducing energy losses. Although dc electric systems offer many advantages such as no synchronization and no reactive power, successful implementation of dc systems requires appropriate protection strategies. One unique protection challenge brought by the dc systems is dc arc faults. A dc arc fault is generated when there is a gap in the conductor due to insulation degradation and current is used to bridge the gap, resulting in an arc with very high temperature. Such a fault if it goes undetected and is not extinguished can cause damage to the entire system and cause fires. The purpose of the research is to study the effect of the dc arc fault at different locations in the hybrid ac/dc microgrid and provide insight on the reliability of the grid components when it is impacted by arc faults at various locations in the grid. The impact of dc arc fault at different locations on the performance of the PV array, wind generation, and constant power loads (CPL) interfaced with dc/dc converters is studied. MATLAB/Simulink is used to model the hybrid ac/dc microgrid and arc fault.
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Mclyman, C. W.
1983-01-01
Compact dc/dc inverter uses single integrated-circuit package containing six inverter gates that generate and amplify 100-kHz square-wave switching signal. Square-wave switching inverts 10-volt local power to isolated voltage at another desired level. Relatively high operating frequency reduces size of filter capacitors required, resulting in small package unit.
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2010-10-14
... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-30, DC-10-30F (KDC-10... following new airworthiness directive (AD): 2010-21-13 McDonnell Douglas Corporation: Amendment 39-16473... November 18, 2010. Affected ADs (b) None. Applicability (c) This AD applies to McDonnell Douglas...
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2010-11-05
...-1044; Directorate Identifier 2010-NM-033-AD] RIN 2120-AA64 Airworthiness Directives; McDonnell Douglas..., 2007) and adding the following new AD: McDonnell Douglas Corporation: Docket No. FAA-2010-1044.... Applicability (c) This AD applies to all McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...
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Overview of Multi-DC-Bus Solutions for DC Microgrids
DEFF Research Database (Denmark)
Ricchiuto, D.; Mastromauro, R.A.; Liserre, Marco
2013-01-01
DC Microgrids have recently received a lot of attention in the last years due to high penetration of renewable energy sources as well as distributed energy storage systems. In the future DC microgrids could be preferable respect to AC microgrids in terms of redundancy since multi-DC-Bus solutions...... could provide a continuative power supply to the loads. An overview of Multi-DC-Bus solutions is presented in this paper. The performances are compared on the basis of possible DC microgrid configurations, redundancy, different DC voltage levels....
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Steven Spielberg's "Amistad": Film as History and the Trivializing of History Teaching.
Butchart, Ronald E.
1999-01-01
Asserts that Steven Spielberg's film "Amistad" fictionalizes the overall facts of the case by inaccurately portraying many of the events that occurred. Explains that the myth-making tradition of Hollywood changes the messages derived from the Amistad court case. Critiques the teaching kit that corresponds to the movie. (CMK)
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DC to DC power converters and methods of controlling the same
Steigerwald, Robert Louis; Elasser, Ahmed; Sabate, Juan Antonio; Todorovic, Maja Harfman; Agamy, Mohammed
2012-12-11
A power generation system configured to provide direct current (DC) power to a DC link is described. The system includes a first power generation unit configured to output DC power. The system also includes a first DC to DC converter comprising an input section and an output section. The output section of the first DC to DC converter is coupled in series with the first power generation unit. The first DC to DC converter is configured to process a first portion of the DC power output by the first power generation unit and to provide an unprocessed second portion of the DC power output of the first power generation unit to the output section.
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Review of The Joy of x: A Guided Tour of Math, from One to Infinity by Steven Strogatz
Michael T. Catalano
2014-01-01
Strogatz, Steven. The Joy of x: A Guided Tour of Math, from One to Infinity, (New York, NY, Houghton Mifflin Harcourt, 2012). 316 pp. ISBN 978-0-547-51765-0 The Joy of x: A Guided Tour of Math, from One to Infinity, by Steven Strogatz, is an engaging and example-filled argument for mathematics as a valuable and enjoyable activity. The thirty chapters are divided into six parts, entitled Numbers, Relationships, Shapes, Change, Data, and Frontiers. The discussion ranges from intuitive expl...
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Directory of Open Access Journals (Sweden)
R. Silva-Ortigoza
2014-01-01
Full Text Available This paper presents a hierarchical controller that carries out the angular velocity trajectory tracking task for a DC motor driven by a DC/DC Buck converter. The high level control is related to the DC motor and the low level control is dedicated to the DC/DC Buck converter; both controls are designed via differential flatness. The high level control provides a desired voltage profile for the DC motor to achieve the tracking of a desired angular velocity trajectory. Then, a low level control is designed to ensure that the output voltage of the DC/DC Buck converter tracks the voltage profile imposed by the high level control. In order to experimentally verify the hierarchical controller performance, a DS1104 electronic board from dSPACE and Matlab-Simulink are used. The switched implementation of the hierarchical average controller is accomplished by means of pulse width modulation. Experimental results of the hierarchical controller for the velocity trajectory tracking task show good performance and robustness against the uncertainties associated with different system parameters.
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Steven Spielberg peab oma uut filmi koostööks Stanley Kubrickuga
2001-01-01
30. juunil üheaegselt Jaapanis ja USAs esilinastub Steven Spielbergi "Tehisintellekt" ("A.I. Artificial Intelligence"), mille kohta režissöör Tokyos pressikonverentsil väitis, et see on õieti Stanley Kubricku film, kuna põhineb temast järelejäänud 90-leheküljelisel ideeprojektil
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Liwen Pan; Chengning Zhang
2016-01-01
This paper presents an on-board vehicular battery charger that integrates bidirectional AC/DC converter and DC/DC converter to achieve high power density for application in electric vehicles (EVs). The integrated charger is able to transfer electrical energy between the battery pack and the electric traction system and to function as an AC/DC battery charger. The integrated charger topology is presented and the design of passive components is discussed. The control schemes are developed for m...
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PENGGUNAAN FUZZY LOGIC UNTUK KONTROL PARALLEL CONVERTER DC-DC
Directory of Open Access Journals (Sweden)
Bambang Prio Hartono
2012-09-01
Full Text Available Abstract: Using system fuzzy logic as control technology have been used on low load dc-dc converter with combined parallel compiled dc-dc converter can obtain big load. With existence of differrence of component parameter and each parallel compiled converter can obtained different current and voltage output. Function of controller for to do adjustment, so that current which is applied to load by each converter can be obtained difference error as small as possible or same. The object of research is developing design of large signal dc-dc converter which is combined with using FLC so that obtain better performance. To get better performance have been made plant model and simulation with CDE method. The more systematic system and design is needed to overcome bigger load on dc-dc converter, so that parallel compiled current master slave control system on dc-dc converter with using fuzzy logic controller is used. Result of research showed that error or difference of current which is applied to load can handled by fuzzy logic controller. Technic of current and voltage controller co to do adjustment current and voltage distribution equally to load. Distribution of iL1,iL2 and output voltage Vo on dc-dc converter with load 2,25 until 7,875 and voltage 100 until 120 volt, load current beetwen 12 until 48, % relatif error Vo 0,4% until 0,9%.
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Full range ZVS DC-DC converter
International Nuclear Information System (INIS)
Upadhyay, Rinki; Badapanda, M.K.; Hannurkar, P.R.
2011-01-01
A 500 V, 24 Amp DC-DC converter with digital signal processor (DSP) based control and protection has been designed, fabricated and tested. Its power circuit consists of IGBT based single phase inverter bridge, ferrite transformer and diode rectifier. All IGBTs in the inverter bridge are operated in zero voltage switching (ZVS) mode to minimize switching losses thereby increasing the efficiency of the converter significantly. The efficiency of this converter is measured to be greater than 97% at full load. In a conventional full bridge inverter, typically ZVS is achieved under full load condition while at light load ZVS is lost. An auxiliary LC circuit has been intentionally incorporated in this converter to achieve ZVS even at light loaded conditions. Detailed simulation of the converter circuit is carried out and crucial waveforms have been presented in this paper. Microchip make dsPIC30F2020 DSP is employed to provide phase shifted PWMs to IGBTs in the inverter bridge. All the crucial parameters are also monitored by this DSP and in case of any unfavorable conditions, the converter is tripped off. Suitable experiments were carried out in this DC-DC converter under different loaded conditions and a close match between the simulated and experimental results were obtained. Such DC-DC converters can be connected in series or parallel for the development of solid state modular power supplies for various applications. (author)
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TOPOLOGICAL REVIEW AND ANALYSIS OF DC-DC BOOST CONVERTERS
Directory of Open Access Journals (Sweden)
V. INDRA GANDHI
2017-06-01
Full Text Available DC voltage boost up is essential in numerous applications; especially considering Photovoltaic (PV based renewable power generation system. The conventional DC-DC boost converter is the most admired configuration for this scheme, even if the converter efficiency is restricted at duty cycle near to maximum value. In order to find solution to the problem and improve its conversion capability, many converter configurations have been implemented so far. With this circumstance, this research work proposes to give overview of a few most imperative research works related to DC-DC boost converters. Some configurations are covered and classified basically based on the application. The major benefits and disadvantages related to the available techniques are also briefly conveyed. At last, a proper evaluation is recognized among the important types of DC-DC boost converters in terms of efficiency, number of components, and stability.
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Pham, A J; Schilling, M W; Yoon, Y; Kamadia, V V; Marshall, D L
2008-05-01
The objectives of this study were to characterize volatile compounds and to determine the characteristic aromas associated with impact compounds in 4 fish sauces using solid-phase micro-extraction, gas chromatography-mass spectrometry, Osme, and gas chromatography olfactometry (SPME-Osme-GCO) coupled with Stevens' Power Law. Compounds were separated using GCMS and GCO and were identified with the mass spectral database, aroma perceived at the sniffing port, retention indices, and verification of compounds by authentic standards in the GCMS and GCO. Aromas that were isolated and present in all 4 fish sauce samples at all concentrations included fishy (trimethylamine), pungent and dirty socks (combination of butanoic, pentanoic, hexanoic, and heptanoic acids), cooked rice and buttery popcorn (2,6-dimethyl pyrazine), and sweet and cotton candy (benzaldehyde). All fish sauces contained the same aromas as determined by GCO and GCMS (verified using authentic standard compounds), but the odor intensity associated with each compound or group of compounds was variable for different fish sauce samples. Stevens' Power Law exponents were also determined using this analytical technique, but exponents were not consistent for the same compounds that were found in all fish sauces. Stevens' Power Law exponents ranged from 0.14 to 0.37, 0.24 to 0.34, 0.09 to 0.21, and 0.10 to 0.35 for dirty socks, fishy, buttery popcorn, and sweet aromas, respectively. This demonstrates that there is variability in Stevens' Power Law exponents for odorants within fish sauce samples.
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Energy Technology Data Exchange (ETDEWEB)
Polenov, Dieter
2010-01-15
The paper discusses DC/DC converters for integration of double layer condensers into the onboard power system. First, requirements on DC/DC converters are listed and compared on the basis of three exemplary applications. A DC/DC converter concept is developed for decoupling transient high-power loads like electric steering systems. Three different topologies are compared using a specially developed method in order to find the best solution for the given application. In order to establish adequate criteria for selecting the switching frequency and inductivities of storage throttles, the influence of the trottle power change on the switching characteristics of the MOSFETs and on certain ranges of EMP interference emissions is investigated. As methods of optimising the operation of the synchronous rectifiers, parallel connection of Schottky diodes and synchronous rectifiers as well as the variation of the shut-off dead times of synchronous rectifiers were investigated. Further, a concept for converter control was developed in consideration of the intended application and topology. Finally, selected aspects for implementation of the DC/DC converter concept are presented as well as the results of experimental investigations.
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Alfred Russel Wallace’s record of his consignments to Samuel Stevens, 1854-1861
Baker, D.B.
2001-01-01
An annotated facsimile of those pages of Alfred Russel Wallace’s notebook recording his consignments from the Malay Archipelago to his London agent, Samuel Stevens, is provided. Records of individual consignments are linked with the stages of Wallace’s and Charles Allen’s itineraries to which they
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LX-04 VIOLENCE MEASUREMENTS- STEVEN TESTS IMPACTED BY PROJECTILES SHOT FROM A HOWITZER GUN
International Nuclear Information System (INIS)
Chidester, S K; Vandersall, K S; Switzer, L L; Tarver, C M
2005-01-01
Characterization of the reaction violence of LX-04 explosive (85% HMX and 15% Viton A by weight) was obtained from Steven Impact Tests performed above the reaction initiation threshold. A 155 mm Howitzer propellant driven gas gun was used to accelerate the Steven Test projectiles in the range of approximately 170-300 m/s to react (ignite) the LX-04 explosive. Blast overpressure gauges, acoustic microphones, and high-speed photography characterized the level of high explosive reaction violence. A detonation in this velocity range was not observed and when comparing these results (and the Susan test results) with that of other HMX based explosives, LX-04 has a more gradual reaction violence slope as the impact velocity increases. The high binder content (15%) of the LX-04 explosive is believed to be the key factor to the lower level of violence
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Some assembly required: Contributions of Tom Stevens' lab to the V-ATPase field.
Graham, Laurie A; Finnigan, Gregory C; Kane, Patricia M
2018-06-01
Tom Stevens' lab has explored the subunit composition and assembly of the yeast V-ATPase for more than 30 years. Early studies helped establish yeast as the predominant model system for study of V-ATPase proton pumps and led to the discovery of protein splicing of the V-ATPase catalytic subunit. The Vma - phenotype, characteristic of loss-of-V-ATPase activity in yeast was key in determining the enzyme's subunit composition via yeast genetics. V-ATPase subunit composition proved to be highly conserved among eukaryotes. Genetic screens for new vma mutants led to identification of a set of dedicated V-ATPase assembly factors and helped unravel the complex pathways for V-ATPase assembly. In later years, exploration of the evolutionary history of several V-ATPase subunits provided new information about the enzyme's structure and function. This review highlights V-ATPase work in the Stevens' lab between 1987 and 2017. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
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Chaos analysis and chaotic EMI suppression of DC-DC converters
Zhang, Bo
2014-01-01
Introduces chaos theory, its analytical methods and the means to apply chaos to the switching power supply design DC-DC converters are typical switching systems which have plenty of nonlinear behaviors, such as bifurcation and chaos. The nonlinear behaviors of DC-DC converters have been studied heavily over the past 20 years, yet researchers are still unsure of the practical application of bifurcations and chaos in switching converters. The electromagnetic interference (EMI), which resulted from the high rates of changes of voltage and current, has become a major design criterion in DC-DC co
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Full wave dc-to-dc converter using energy storage transformers
Moore, E. T.; Wilson, T. G.
1969-01-01
Full wave dc-to-dc converter, for an ion thrustor, uses energy storage transformers to provide a method of dc-to-dc conversion and regulation. The converter has a high degree of physical simplicity, is lightweight and has high efficiency.
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Pulsewidth modulated DC-to-DC power conversion circuits, dynamics, and control designs
Choi, Byungcho
2013-01-01
This is the definitive reference for anyone involved in pulsewidth modulated DC-to-DC power conversion Pulsewidth Modulated DC-to-DC Power Conversion: Circuits, Dynamics, and Control Designs provides engineers, researchers, and students in the power electronics field with comprehensive and complete guidance to understanding pulsewidth modulated (PWM) DC-to-DC power converters. Presented in three parts, the book addresses the circuitry and operation of PWM DC-to-DC converters and their dynamic characteristics, along with in-depth discussions of control design of PWM DC-to
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2013-04-09
... for Sustainable Fisheries, Northeast Region, NMFS (Assistant Regional Administrator), has made a... University Cooperative Extension of Suffolk County, NY. Regulations under the Magnuson-Stevens Fishery... limits to conduct onboard sampling. This project proposes to evaluate bottom trawl modifications as a...
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2013-05-30
..., Dartmouth, School for Marine Science and Technology. Regulations under the Magnuson-Stevens Fishery.... SUPPLEMENTARY INFORMATION: The University of Massachusetts, Dartmouth, School for Marine Science and Technology... study and examining the influence of temperature. To facilitate compensation fishing in support of this...
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2013-06-27
... Massachusetts, Dartmouth, School for Marine Science and Technology. Regulations under the Magnuson-Stevens..., 978-281-9177. SUPPLEMENTARY INFORMATION: The University of Massachusetts, Dartmouth, School for Marine... preliminary determination that an exempted fishing permit application contains all of the required information...
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2013-04-12
... Massachusetts, Dartmouth, School for Marine Science and Technology. Regulations under the Magnuson-Stevens... preliminary determination that an exempted fishing permit application contains all of the required information....'' Fax: (978) 281-9135. FOR FURTHER INFORMATION CONTACT: Jason Berthiaume, Fishery Management Specialist...
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Triple voltage dc-to-dc converter and method
Su, Gui-Jia
2008-08-05
A circuit and method of providing three dc voltage buses and transforming power between a low voltage dc converter and a high voltage dc converter, by coupling a primary dc power circuit and a secondary dc power circuit through an isolation transformer; providing the gating signals to power semiconductor switches in the primary and secondary circuits to control power flow between the primary and secondary circuits and by controlling a phase shift between the primary voltage and the secondary voltage. The primary dc power circuit and the secondary dc power circuit each further comprising at least two tank capacitances arranged in series as a tank leg, at least two resonant switching devices arranged in series with each other and arranged in parallel with the tank leg, and at least one voltage source arranged in parallel with the tank leg and the resonant switching devices, said resonant switching devices including power semiconductor switches that are operated by gating signals. Additional embodiments having a center-tapped battery on the low voltage side and a plurality of modules on both the low voltage side and the high voltage side are also disclosed for the purpose of reducing ripple current and for reducing the size of the components.
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Stevens-Johnson syndrome following use of metronidazole in a dental patient.
Mazumdar, Goutameswar; Shome, Koushik
2014-01-01
Metronidazole alone rarely causes Stevens-Johnson syndrome (SJS). We present a case of an elderly male patient who, following metronidazole use, developed neurological symptoms followed by pain and blisters on both soles, erythema of face and neck, scrotal itching and erosion, and hemorrhagic encrustation around the lips and oral mucous membrane. Initial neurological symptoms followed by mucocutaneous manifestation of SJS following metronidazole use is probably a new presentation of this case.
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Gupta, Lalit Kumar; Martin, Abhay Mani; Agarwal, Nidheesh; D'Souza, Paschal; Das, Sudip; Kumar, Rajesh; Pande, Sushil; Das, Nilay Kanti; Kumaresan, Muthuvel; Kumar, Piyush; Garg, Anubhav; Singh, Saurabh
2016-01-01
Stevens-Johnson syndrome and toxic epidermal necrolysis are severe, life-threatening mucocutaneous adverse drug reactions with a high morbidity and mortality that require immediate medical care. The various immunomodulatory treatments include systemic corticosteroids, cyclosporine, intravenous immunoglobulin, cyclophosphamide, plasmapheresis and tumor necrosis factor-α inhibitors. The ideal therapy of Stevens-Johnson syndrome/toxic epidermal necrolysis still remains a matter of debate as there are only a limited number of studies of good quality comparing the usefulness of different specific treatments. The aim of this article is to comprehensively review the published medical literature and frame management guidelines suitable in the Indian perspective. The Indian Association of Dermatologists, Venereologists and Leprologists (IADVL) assigned the task of preparing these guidelines to its special interest group on cutaneous adverse drug reactions. The group performed a comprehensive English language literature search for management options in Stevens-Johnson syndrome/toxic epidermal necrolysis across multiple databases (PubMed, EMBASE, MEDLINE and Cochrane) for keywords (alone and in combination) and MeSH items such as "guidelines," "Stevens-Johnson syndrome," "toxic epidermal necrolysis," "corticosteroids," "intravenous immunoglobulin," "cyclosporine" and "management." The available evidence was evaluated using the strength of recommendation taxonomy and graded using a three-point scale. A draft of clinical recommendations was developed on the best available evidence which was also scrutinized and critically evaluated by the IADVL Academy of Dermatology. Based on the inputs received, this final consensus statement was prepared. A total of 104 articles (meta-analyses, prospective and retrospective studies, reviews [including chapters in books], previous guidelines [including Indian guidelines of 2006] and case series) were critically evaluated and the evidence
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Agamy, Mohammed; Elasser, Ahmed; Sabate, Juan Antonio; Galbraith, Anthony William; Harfman Todorovic, Maja
2014-09-09
A distributed photovoltaic (PV) power plant includes a plurality of distributed dc-dc converters. The dc-dc converters are configured to switch in coordination with one another such that at least one dc-dc converter transfers power to a common dc-bus based upon the total system power available from one or more corresponding strings of PV modules. Due to the coordinated switching of the dc-dc converters, each dc-dc converter transferring power to the common dc-bus continues to operate within its optimal efficiency range as well as to optimize the maximum power point tracking in order to increase the energy yield of the PV power plant.
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2011-03-03
.... The pollock peer-reviewed benchmark stock assessment review (Stock Assessment Workshop, or SAW, 50... overfishing, rebuild overfished stocks, achieve optimum yield (OY), and minimize the economic impact of... Management Act (Magnuson-Stevens Act). This action would revise the biological reference points and stock...
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The performance of the DC motor by the PID controlling PWM DC-DC boost converter
Can, Erol; Sayan, Hasan Hüseyin
2017-01-01
This paper presents the PID controlling direct current (DC) to the direct current boost converter feds DC motor which has a 3.68 kW and 240 V of DC voltage input on its characteristics. What is first formed is the boost converter mathematical model at the design stage. Secondly, a mathematical model of the DC motor is created so that the boost converter with the machine can be established and modeled at the Matlab Simulink. The PID controller is considered for arranging a pulse width modulati...
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On and off controlled resonant dc-dc power converter
DEFF Research Database (Denmark)
2015-01-01
The present invention relates to a resonant DC-DC power converter comprising an input side circuit comprising a positive and a negative input terminal for receipt of an input voltage or current and an output side circuit comprising positive and negative output terminals for supply of a converter...... output voltage and connection to a converter load. The resonant DC-DC power converter further comprises a rectification circuit connected between an output of a resonant network and the output side circuit. The resonant network is configured for alternatingly being charged from the input voltage...... or current and discharged through the rectification circuit by a first controllable switch arrangement in accordance with a first switch control signal. A second controllable switch arrangement of the resonant DC-DC power converter is configured to select a first impedance characteristic of the resonant...
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The Topologies Research of a Soft Switching Bidirectional DC/DC Converter
DEFF Research Database (Denmark)
Zhang, Qi; Zhang, Yongping; Sun, Xiangdong
2017-01-01
A soft-switching solution implemented to the traditional bidirectional DC/DC converter is developed. The soft-switching cell, which composed of three auxiliary switches, one resonant capacitor and one resonant inductor, is equipped in the traditional bidirectional DC/DC converter to realize circuit...... circle. And the proposed topology of bidirectional soft-switching dc-dc converter(TASBC) performs ideal soft switching at boost operations. The characteristics of the proposed converter has been verified by MATLAB simulations and experimental results....
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2010-05-17
... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 9-30, DC-9-40, and DC-9-50 Series Airplanes... airworthiness directive (AD) for certain Model DC-9-30, DC-9-40, and DC-9-50 series airplanes. This AD requires... this AD to detect and correct the potential for an arc/spark condition to occur within the fuel boost...
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Directory of Open Access Journals (Sweden)
Haojie Wang
2016-07-01
Full Text Available It is a common practice for storage batteries to be connected to DC microgrid buses through DC-DC converters for voltage support on islanded operation mode. A feed-forward control based dual-loop constant voltage PI control for three-branch interleaved DC-DC converters (TIDC is proposed for storage batteries in DC microgrids. The working principle of TIDC is analyzed, and the factors influencing the response rate based on the dual-loop constant voltage control for TIDC are discussed, and then the method of feed-forward control for TIDC is studied to improve the response rate for load changing. A prototype of the TIDC is developed and an experimental platform is built. The experiment results show that DC bus voltage sags or swells caused by load changing can be reduced and the time for voltage recovery can be decreased significantly with the proposed feed-forward control.
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DEFF Research Database (Denmark)
Wang, Haojie; Han, Minxiao; Yan, Wenli
2016-01-01
It is a common practice for storage batteries to be connected to DC microgrid buses through DC-DC converters for voltage support on islanded operation mode. A feed-forward control based dual-loop constant voltage PI control for three-branch interleaved DC-DC converters (TIDC) is proposed...... for storage batteries in DC microgrids. The working principle of TIDC is analyzed, and the factors influencing the response rate based on the dual-loop constant voltage control for TIDC are discussed, and then the method of feed-forward control for TIDC is studied to improve the response rate for load...... changing. A prototype of the TIDC is developed and an experimental platform is built. The experiment results show that DC bus voltage sags or swells caused by load changing can be reduced and the time for voltage recovery can be decreased significantly with the proposed feed-forward control....
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Martinez-Rodrigo, Fernando; Herrero-De Lucas, Luis Carlos; de Pablo, Santiago; Rey-Boue, Alexis B.
2017-01-01
This paper examines the question of how to use project-based learning to increase student performance and satisfaction in a power electronics course addressing the topics of dc/dc and dc/ac converters, the assembly of a dc/dc converter, and the use of a commercial speed drive. A detailed presentation of the methodology is shown, and the results…
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Directory of Open Access Journals (Sweden)
Sevil Toka
2012-09-01
Full Text Available Objective: Monnose-Binding lectin (MBL appears to play an important role in the immune system. The genetic polymorphisms in the MBL2 gene can result in a reduction of serum levels, leading to a predisposition to recurrent infection. The aim of this study is to investigate the influence of a polymorphism in codon 54 of the MBL2 gene on the susceptibility to Erythema Multiforme, Stevens-Johnson Syndrome and Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis Overlap Syndrome (EM, SJS and SJS/TEN overlap syndrome. Material and Methods: Our study included 64 patients who were clinically and/or histopathologically diagnosed with EM, SJS, and SJS/TEN overlap syndrome and 66 healthy control subjects who were genotyped for the MBL2 gene codon 54 polymorphism using the PCR-RFLP method. For all statistical analyses, the level of significance was set at p<0.05. Results: The prevalence of the B allele was 18% in the EM, SJS and SJS/TEN patient groups and 13% in the control group. No significant differences in allele frequencies of any polymorphism were observed between the patient and control groups, although the B allele was more frequent in the patient groups (p=0.328.Conclusion: Our results provide no evidence of a relationship between MBL2 gene codon 54 polymorphism and the susceptibility to EM, SJS and SJS/TEN overlap syndrome. However, these findings should be confirmed in studies with a larger sample size.
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Improved Control Strategy for T-type Isolated DC/DC Converters
DEFF Research Database (Denmark)
Liu, Dong; Deng, Fujin; Wang, Yanbo
2017-01-01
T-type isolated DC/DC converters have recently attracted attention due to their numerous advantages, including few components, low cost, and symmetrical operation of transformers. This study proposes an improved control strategy for increasing the efficiency of T-type isolated DC/DC converters....... Under the proposed strategy, the primary circulating current flows through the auxiliary switches (metal–oxide–semiconductor field-effect transistors) instead of their body diodes in free-wheeling periods. Such feature can reduce conduction losses, thereby improving the efficiency of T-type isolated DC...
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Forlini, Matteo; Adabache-Guel, Tania; Bratu, Adriana; Rossini, Paolo; Mingaine, Mpekethu Sam; Cavallini, Gian Maria; Forlini, Cesare
2014-01-01
To report successful treatment of refractive glaucoma in a patient submitted to osteo-odonto-keratoprosthesis surgery for Stevens-Johnson syndrome. An interventional case report. The patient is a 62-year-old Indian man with known Stevens-Johnson syndrome since 1972 secondary to tetracycline therapy, with bilateral dry eye and corneal blindness. He underwent symblepharon release surgery with mucous membrane graft in both eyes. Osteo-odonto-keratoprosthesis surgery was later performed on the left eye. He was submitted to 2 Ahmed valve implants to control secondary glaucoma but visual fields continued to worsen; hence, he underwent endoscopic 140° cyclophotocoagulation with a good control of IOP. Endoscopic cyclophotocoagulation as alternative treatment provides good results in refractory glaucoma after osteo-odonto-keratoprosthesis surgery.
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2012-03-23
... Multispecies Fishery Management Plan which was approved on March 8, 2012. This action amends the Northeast Multispecies Fishery Management Plan to explicitly define and facilitate the effective operation of state.... 110901552-20494-02] RIN 0648-BB34 Magnuson-Stevens Fishery Conservation and Management Act Provisions...
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2011-09-15
... to estimate total haddock catch by the herring midwater trawl fleet in these herring management areas.... 110627355-1539-02] RIN 0648-BB08 Magnuson-Stevens Fishery Conservation and Management Act Provisions... the NE Multispecies Fishery Management Plan (FMP), which increases the haddock incidental catch cap...
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High power density dc/dc converter: Selection of converter topology
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.
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The Great American Divide: The Military-Civilian Gap
2012-03-14
Steven A. Bank, Kirk J. Stark, and Joseph J. Thorndike provide a historical account of America’s war-time fiscal policies for the major American wars...accessed January 16, 2012). 63 Steven A. Bank, Kirk J. Stark, Joseph J. Thorndike , War and Taxes (Washington, DC: The Urban Institute Press, 2008
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Directory of Open Access Journals (Sweden)
Liwen Pan
2016-06-01
Full Text Available This paper presents an on-board vehicular battery charger that integrates bidirectional AC/DC converter and DC/DC converter to achieve high power density for application in electric vehicles (EVs. The integrated charger is able to transfer electrical energy between the battery pack and the electric traction system and to function as an AC/DC battery charger. The integrated charger topology is presented and the design of passive components is discussed. The control schemes are developed for motor drive system and battery-charging system with a power pulsation reduction circuit. Simulation results in MATLAB/Simulink and experiments on a 30-kW motor drive and 3.3-kW AC/DC charging prototype validate the performance of the proposed technology. In addition, power losses, efficiency comparison and thermal stress for the integrated charger are illustrated. The results of the analyses show the validity of the advanced integrated charger for electric vehicles.
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Environmental and economic benefits of sustainable development
International Nuclear Information System (INIS)
McKay, P.; Kelly, B.; Passmore, J.
1997-01-01
The panel on sustainable development was moderated by Paul McKay of the Wildside Foundation. Bryan Kelly, Director of Environment and Sustainable Development at Ontario Hydro, and Jeffrey Passmore of Passmore Associates International were the panel members. Bryan Kelly described the objectives of his group's program as reducing market barriers, and get renewables on a level playing field through technological advances to ensure that ' when Ontario Hydro or its successors make decisions about new capacity, renewables will be a viable option and will not be dismissed out of hand'. To illustrate the approach, he described several ongoing research and development projects. Jeffrey Passmore reported on a study he conducted for the Canadian Wind Energy Association and Environment Canada to determine the environmental and economic benefits of wind energy in Canada. He estimated achievable wind energy potential in Canada at around 6400 MW by 2010. He stressed wind energy's potential for job creation and CO 2 reduction as the principal economic and environmental benefits
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RESONANT STEP-DOWN DC-DC POWER CONVERTERS
DEFF Research Database (Denmark)
2015-01-01
The present invention relates to a resonant step-down 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...... charged from the input voltage and discharged to the output capacitor through the galvanic isolation barrier by a semiconductor switch arrangement in accordance with a switch control signal to produce the converter output voltage. The resonant step-down DC-DC power converter comprises an electrical short......-circuit connection across the galvanic isolation barrier connecting, in a first case, the second negative electrode of the output capacitor to the positive input terminal of the primary side circuit or, in a second case, connecting the second positive electrode of the output capacitor to the negative input terminal...
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International Nuclear Information System (INIS)
Ferreira, M. R.; Amado, A.; Jorge, M.; Grillo, I. M.
2011-01-01
Background: Stevens Johnson Syndrome and Erythema Multiforme are hypersensitivity skin reactions generally arising in the context of multiple causes. Radiation therapy is considered to be one of these causes, although most reports are hindered by concomitant medications. Aim: The aim of this paper was to present a case of Stevens Johnson Syndrome arising in a patient undergoing gynaecological brachytherapy with an unusual presentation. Case:We describe a case of a 56-year-old woman with endometrial cancer undergoing adjuvant gynaecological radiotherapy. While undergoing a gynaecological brachytherapy boost, she developed bilateral conjunctivitis that progressed to oral mucositis and pruritic erythema with sloughing of the skin on her arms and legs but not the torso or irradiated fields (namely the vaginal mucosa). Conclusion: This case illustrates the association of RT/SJS; however, it also raises the question of patients undergoing RT being more susceptible to SJS as opposed to a direct cause of the disease. (authors)
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Atmel Microcontroller Based Soft Switched PWM ZVS Full Bridge DC to DC Converter
Directory of Open Access Journals (Sweden)
DEEPAK KUMAR NAYAK
2010-12-01
Full Text Available This paper deals with the simulation and implementation of soft switched PWM ZVS full bridge DC to DC converter. The 48V DC is efficiently reduced to 12V DC using a DC to DC converter. This converter has advantages like reduced switching losses, stresses and EMI. Input DC is converted into high frequency AC and it is stepped down to 12V level. Later it is rectified using a full wave rectifier. Laboratory model of microcontroller based DC to DC converter is fabricated and tested. The experimental results are compared with the simulation results.
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Quasi-Z-Source Half-Bridge DC-DC Converter for Photovoltaic Applications
Vinnikov, D; Chub, A; Husev, O; Zaķis, J
2015-01-01
This paper presents a novel quasi-Z-source halfbridge galvanically isolated DC-DC converter intended for the photovoltaic applications. The topology could be envisioned as an alternative to the boost half-bridge DC-DC converter but the benefit of its symmetric structure reduces the threat of transformer saturation due to the dc flux. The proposed converter features the continuous input current and could be used either with one or two input voltage sources.
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DC motor operation controlled from a DC/DC power converter in pulse mode with low duty cycle
Stefanov, Goce; Kukuseva, Maja; Citkuseva Dimitrovska, Biljana
2016-01-01
In this paper pulse mode of operation of DC motor controlled by DC/DC power converter is analyzed. DC motor operation with time intervals in which the motor operates without output load is of interest. In this mode it is possible the motor to restore energy. Also, in the paper are represented calculations for the amount of the restored energy in the pulse mode operation of the motor for different duty cycles.
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Control of the DC-DC Converter used into Energy Generation System
International Nuclear Information System (INIS)
Bizon, Nicu; Oproescu, Mihai
2006-01-01
This paper presents an investigation of the DC-DC Converter controller used into Energy Generation System. The full bridge is used into an Energy Generation System (EGS) as second power interface between the energy source and the high DC bus. The simulation results show that the DC-DC Converter behavior can be improved using a well designed PI control surface. The used Simulink models for the EGS blocks and some design considerations are presented, too. (authors)
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2013-10-25
.../13monkeia.html . Copies of the small entity compliance guide are available at the following internet address... Procedure Act (APA). Pursuant to section 305(c)(3)(B) of the Magnuson-Stevens Act, management measures... APA. Comments and Responses Fifteen comments were received during the public comment period on the...
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Eliminating cancer stem cells: an interview with CCR’s Steven Hou | Center for Cancer Research
Steven Hou, Ph.D., senior investigator in the Basic Research Laboratory at the Center for Cancer Research describes his latest research that has uncovered potential ways to eliminate cancer stem cells and may offer hope to patients with reoccurring tumors. Learn more...
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Novel composite resonance DC-DC converter with voltage doubler rectifier
Kato, Hisatsugu; Matsuo, Hirohumi; Eguchi, Masaki; Sakamoto, Yukitaka; Nakaishi, Masaki
2009-01-01
This paper deals with a novel composite resonance DC-DC converter with the voltage doubler rectifier, which is developed to be applied to the power conditioner of the photovoltaic generation system. The proposed DC-DC converter has the current and voltage resonance functions. Therefore, the output voltage regulation can be achieved for the large variations of the input voltage and load. Also, this converter has the high power efficiency. The maximum power efficiency 96.1% can be realized.
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Autoimmune Progesterone Dermatitis Presenting as Stevens-Johnson Syndrome.
Drayer, Sara M; Laufer, Larry R; Farrell, Maureen E
2017-10-01
Autoimmune progesterone dermatitis is an uncommon disease presenting with cyclical skin eruptions corresponding with the menstrual cycle luteal phase. Because symptoms are precipitated by rising progesterone levels, treatment relies on hormone suppression. A 22-year-old nulligravid woman presented with symptoms mistaken for Stevens-Johnson syndrome. A cyclic recurrence of her symptoms was noted, and the diagnosis of autoimmune progesterone dermatitis was made by an intradermal progesterone challenge. After 48 months, she remained refractory to medical management and definitive surgical treatment with bilateral oophorectomy was performed. Autoimmune progesterone dermatitis is a challenging diagnosis owing to its rarity and variety of clinical presentations. Treatment centers on suppression of endogenous progesterone and avoidance of exogenous triggers. When these modalities fail, surgical management must be undertaken.
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Ultra-high Efficiency DC-DC Converter using GaN Devices
DEFF Research Database (Denmark)
Ramachandran, Rakesh
2016-01-01
properties of GaN devices can be utilized in power converters to make them more compact and highly efficient. This thesis entitled “Ultra-high Efficiency DC-DC Converter using GaN devices” focuses on achieving ultra-high conversion efficiency in an isolated dc-dc converter by the optimal utilization of Ga...... for many decades. However, the rate of improvement slowed as the silicon power materials asymptotically approached its theoretical bounds. Compared to Si, wideband gap materials such as Silicon Carbide (SiC) and Gallium Nitride (GaN) are promising semiconductors for power devices due to their superior...... in this thesis. Efficiency measurements from the hardware prototype of both the topologies are also presented in this thesis. Finally, the bidirectional operation of an optimized isolated dc-dc converter is presented. The optimized converter has achieved an ultra-high efficiency of 98.8% in both directions...
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2010-10-05
... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-30, DC-10-30F, DC-10-30F (KC-10A and KDC-10...-13 McDonnell Douglas Corporation: Amendment 39-16448; Docket No. FAA-2010-0553; Directorate.... Applicability (c) This AD applies to McDonnell Douglas Corporation Model DC- 10-30, DC-10-30F, DC-10-30F (KC-10A...
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Directory of Open Access Journals (Sweden)
Sergio Ignacio Serna-Garcés
2016-03-01
Full Text Available Stand-alone power systems based on renewable energy sources are used to replace generators based on fossil fuels. Those renewable power systems also require Energy Storage Devices (ESD interfaced by a charger/discharger power converter, which consist of a bidirectional DC/DC converter, and a DC bus. This paper proposes a single sliding-mode controller (SMC for the charger/discharger DC/DC converter to provide a stable DC bus voltage in any operation condition: charging or discharging the ESD, or even without any power exchange between the ESD and the DC bus. Due to the non-linear nature of the power converter, the SMC parameters are adapted on-line to ensure global stability in any operation condition. Such stability of the adaptive SMC is mathematically demonstrated using analytical expressions for the transversality, reachability and equivalent control conditions. Moreover, a design procedure for the adaptive SMC parameters is provided in order to ensure the dynamic response required for the correct operation of the load. Finally, simulations and experimental tests validate the proposed controller and design procedure.
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Design and Analysis of Two-Phase Boost DC-DC Converter
Taufik Taufik; Tadeus Gunawan; Dale Dolan; Makbul Anwari
2010-01-01
Multiphasing of dc-dc converters has been known to give technical and economical benefits to low voltage high power buck regulator modules. A major advantage of multiphasing dc-dc converters is the improvement of input and output performances in the buck converter. From this aspect, a potential use would be in renewable energy where power quality plays an important factor. This paper presents the design of a 2-phase 200W boost converter for battery charging application. Analysis of results fr...
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SCM Handbooks for dc-to-dc Converters
Lee, F.; Mohmoud, M.; Yu, Y.
1984-01-01
Two documents aid in design of control modules for dc-to-dc converters. Features of SCM include: Adaptive stability, power component stress limiting, implementation of various control laws, unified design approach. Analysis and quidelines contained in handbooks enable engineer to design SCM circuit and confidently predict resulting overall performance.
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Isolated step-down DC -DC converter for electric vehicles
Kukovinets, O. V.; Sidorov, K. M.; Yutt, V. E.
2018-02-01
Modern motor-vehicle industrial sector is moving rapidly now towards the electricity-driving cars production, improving their range and efficiency of components, and in particular the step-down DC/DC converter to supply the onboard circuit 12/24V of electric vehicle from the high-voltage battery. The purpose of this article - to identify the best circuitry topology to design an advanced step-down DC/DC converters with the smallest mass, volume, highest efficiency and power. And this will have a positive effect on driving distance of electric vehicle (EV). On the basis of computational research of existing and implemented circuit topologies of step-down DC/DC converters (serial resonant converter, full bridge with phase-shifting converter, LLC resonant converter) a comprehensive analysis was carried out on the following characteristics: specific volume, specific weight, power, efficiency. The data obtained was the basis for the best technical option - LLC resonant converter. The results can serve as a guide material in the process of components design of the traction equipment for electric vehicles, providing for the best technical solutions in the design and manufacturing of converting equipment, self-contained power supply systems and advanced driver assistance systems.
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Directory of Open Access Journals (Sweden)
Ajay Kumar
2011-01-01
Full Text Available Carbamazepine and other anticonvulsants are commoner cause of severe adverse cutaneous drug reactions such as erythema multiforme, toxic epidermal necrolysis (TEN, and Stevens-Johnson syndrome (SJS. We report a case of SJS rapidly progressing to TEN with a combination of haloperidol and carbamazepine in a patient with bipolar affective disorder. The pathophysiological mechanism underlying this reaction is discussed.
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2010-12-07
... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 9-30, DC-9-40, and DC-9-50 Series Airplanes...: We are adopting a new airworthiness directive (AD) for the McDonnell Douglas Corporation airplanes... to include an airworthiness directive (AD) that would apply to certain McDonnell Douglas Model DC-9...
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A Component-Reduced Zero-Voltage Switching Three-Level DC-DC Converter
DEFF Research Database (Denmark)
Qin, Zian; Pang, Ying; Wang, Huai
2016-01-01
The basic Zero-Voltage Switching (ZVS) three-level DC-DC converter has one clamping capacitor to realize the ZVS of the switches, and two clamping diodes to clamp the voltage of the clamping capacitor. In order to reduce the reverse recovery loss of the diode as well as its cost, this paper...... proposes to remove one of the clamping diodes in basic ZVS three-level DC-DC converter. With less components, the proposed converter can still have a stable clamping capacitor voltage, which is clamped at half of the dc link voltage. Moreover, the ZVS performance will be influenced by removing the clamping...
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Active pre-filters for dc/dc Boost regulators
Directory of Open Access Journals (Sweden)
Carlos Andrés Ramos-Paja
2014-05-01
Full Text Available This paper proposes an active pre-filter to mitigate the current harmonics generated by classical dc/dc Boost regulators, which generate current ripples proportional to the duty cycle. Therefore, high output voltage conditions, i.e., high voltage conversion ratios, produce high current harmonics that must be filtered to avoid damage or source losses. Traditionally, these current components are filtered using electrolytic capacitors, which introduce reliability problems because of their high failure rate. The solution introduced in this paper instead uses a dc/dc converter based on the parallel connection of the Boost canonical cells to filter the current ripples generated by the Boost regulator, improving the system reliability. This solution provides the additional benefits of improving the overall efficiency and the voltage conversion ratio. Finally, the solution is validated with simulations and experimental results.
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Laboratory manual for pulse-width modulated DC-DC power converters
Kazimierczuk, Marian K
2015-01-01
Designed to complement a range of power electronics study resources, this unique lab manual helps students to gain a deep understanding of the operation, modeling, analysis, design, and performance of pulse-width modulated (PWM) DC-DC power converters. Exercises focus on three essential areas of power electronics: open-loop power stages; small-signal modeling, design of feedback loops and PWM DC-DC converter control schemes; and semiconductor devices such as silicon, silicon carbide and gallium nitride. Meeting the standards required by industrial employers, the lab manual combines program
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A Novel PPFHB Bidirectional DC-DC Converter for Supercapacitor Application
DEFF Research Database (Denmark)
Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael Andreas E.
2009-01-01
This paper presents a novel bidirectional DC-DC converter for the supercapacitor application. In the proposed converter, push-pull forward with half bridge (PPFHB) voltage doubler structure is used to reduce the number of the power switches and get higher voltage gain. Based on phase-shift modula......This paper presents a novel bidirectional DC-DC converter for the supercapacitor application. In the proposed converter, push-pull forward with half bridge (PPFHB) voltage doubler structure is used to reduce the number of the power switches and get higher voltage gain. Based on phase...
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Decentralized Interleaving of Paralleled Dc-Dc Buck Converters: Preprint
Energy Technology Data Exchange (ETDEWEB)
Johnson, Brian B [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rodriguez, Miguel [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sinha, Mohit [University of Minnesota; Dhople, Sairaj [University of Minnesota; Poon, Jason [University of California at Berkeley
2017-09-01
We present a decentralized control strategy that yields switch interleaving among parallel connected dc-dc buck converters without communication. The proposed method is based on the digital implementation of the dynamics of a nonlinear oscillator circuit as the controller. Each controller is fully decentralized, i.e., it only requires the locally measured output current to synthesize the pulse width modulation (PWM) carrier waveform. By virtue of the intrinsic electrical coupling between converters, the nonlinear oscillator-based controllers converge to an interleaved state with uniform phase-spacing across PWM carriers. To the knowledge of the authors, this work represents the first fully decentralized strategy for switch interleaving of paralleled dc-dc buck converters.
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CISH is induced during DC development and regulates DC-mediated CTL activation.
Miah, Mohammad Alam; Yoon, Cheol-Hee; Kim, Joonoh; Jang, Jinah; Seong, Young-Rim; Bae, Yong-Soo
2012-01-01
The cytokine inducible SH2-domain protein (CISH) is a well-known STAT5 target gene, but its role in the immune system remains uncertain. In this study, we found that CISH is predominantly induced during dendritic cell (DC) development from mouse bone marrow (BM) cells and plays a crucial role in type 1 DC development and DC-mediated CTL activation. CISH knockdown reduced the expression of MHC class I, co-stimulatory molecules and pro-inflammatory cytokines in BMDCs. Meanwhile, the DC yield was markedly enhanced by CISH knockdown via cell-cycle activation and reduction of cell apoptosis. Down-regulation of cell proliferation at the later stage of DC development was found to be associated with CISH-mediated negative feedback regulation of STAT5 activation. In T-cell immunity, OT-1 T-cell proliferation was significantly reduced by CISH knockdown in DCs, whereas OT-2 T-cell proliferation was not affected by CISH knockdown. CTLs generated by DC vaccination were also markedly reduced by CISH knockdown, followed by significant impairment of DC-based tumor immunotherapy. Taken together, our data suggest that CISH expression at the later stage of DC development triggers the shutdown of DC progenitor cell proliferation and facilitates DC differentiation into a potent stimulator of CTLs. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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What Recourse for the Principal Abused by Community Activists? The Case of "Stevens v. Tillman."
Menacker, Julius
1990-01-01
"Stevens v. Tillman" illustrates the limited reach of federal law in controversies where community activists use extreme, even illegal, methods to exert their will over objecting school officials. Defamation charges against activists for verbal abuses will apparently be very difficult to sustain, given court views that being called a…
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2011-07-21
... during the course of the FY. Management uncertainty for the LAGC IFQ fleet is considered very low because... incorporate ACT into the LAGC IFQ fleet allocation, but chose not to apply any management uncertainty buffer... Atmospheric Administration 50 CFR Part 648 Magnuson-Stevens Fishery Conservation and Management Act (MSA...
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A Bidirectional Multi-Port DC-DC Converter Integrating Voltage Equalizer
DEFF Research Database (Denmark)
Chen, Jianfei; Hou, Shiying; Deng, Fujin
2015-01-01
A novel bidirectional multi-port dc-dc converter integrating voltage equalizer based on switched-capacitor voltage accumulator (SCVA) is proposed. It has two operating modes of charging and discharging for battery modules. All battery modules are connected in series indirectly and can be equalize...... battery modules with different voltages. Simulation results has shown the feasibility of the proposed converter.......A novel bidirectional multi-port dc-dc converter integrating voltage equalizer based on switched-capacitor voltage accumulator (SCVA) is proposed. It has two operating modes of charging and discharging for battery modules. All battery modules are connected in series indirectly and can be equalized...
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A Current-Fed Isolated Bidirectional DC-DC Converter
DEFF Research Database (Denmark)
Sun, Xiaofeng; Wu, Xiaoying; Shen, Yanfeng
2017-01-01
This paper proposes a current-fed isolated bidirectional DC-DC converter (CF-IBDC) which has the advantages of wide input voltage range, low input current ripple, low conduction losses, and soft switching over the full operating range. Compared with conventional CF-IBDCs, the voltage spikes...
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Bi-Directional DC-DC Converter for PHEV Applications
Energy Technology Data Exchange (ETDEWEB)
Abas Goodarzi
2011-01-31
Plug-In Hybrid Electric Vehicles (PHEV) require high power density energy storage system (ESS) for hybrid operation and high energy density ESS for Electric Vehicle (EV) mode range. However, ESS technologies to maximize power density and energy density simultaneously are not commercially feasible. The use of bi-directional DC-DC converter allows use of multiple energy storage, and the flexible DC-link voltages can enhance the system efficiency and reduce component sizing. This will improve fuel consumption, increase the EV mode range, reduce the total weight, reduce battery initial and life cycle cost, and provide flexibility in system design.
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Determination of input/output characteristics of full-bridge AC/DC/DC converter for arc welding
Stefanov, Goce; Karadzinov, Ljupco; Sarac, Vasilija; Cingoski, Vlatko; Gelev, Saso
2016-01-01
This paper describes the design and practical implementation of AC/DC/DC converter in mode of arc welding. An analysis of the operation of AC/DC/DC converter and its input/output characteristics are determined with computer simulations. The practical part is consisted of AC/DC/DC converter prototype for arc welding with output power of 3 kW and switching frequency of 64 kHz. The operation of AC/DC/DC converter is validated with experimental measurements.
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ITAR Free Commercial-of-the-Shelf DC/DC Converter
Denzinger, Wolfgang; Hintze, Thomas
2014-08-01
A commercial-of-the-shelf (COTS) DC/DC converter for digital space equipment has been developed by ASP under ESA contract with special emphasis on low cost, no use of ITAR listed EEE parts like Mosfets, minimum number of rad-hard digital IC's and a design tolerance against single event effects by appropriate filtering. However, the intention to qualify this discrete converter design for a low cost FM series production was difficult due to the high up-sceening cost of EEE-parts with one lot guarantee and minimum-by. To overcome this problem, in a next step a redesign of the DC/DC converter was performed with all semiconductors like bipolar transistors, rectifiers and zener diodes packaged into hybrids. With this approach it was possible to buy a high number of less expensive wafers or dies from one lot, to perform a lot acceptance test and to integrate the dies into hybrid packages with further up- screening for FM use. The semiconductors have been packaged into three signal hybrids with 44 pins and one power hybrid with 24 pins for the dissipating transistors and rectifiers. The design of the hybrids is such, that all integrated semiconductors can be tested individually. The qualification of four EQM DC/DC converters with different combinations of output voltages has been successfully performed and two FM's have been manufactured and tested.
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Schwab, J. R.
1979-01-01
Performance data obtained through experimental testing of a 22.4 kW traction motor using two types of excitation are presented. Ripple free dc from a motor-generator set for baseline data and pulse width modulated dc as supplied by a battery pack and chopper controller were used for excitation. For the same average values of input voltage and current, the motor power output was independent of the type of excitation. However, at the same speeds, the motor efficiency at low power output (corresponding to low duty cycle of the controller) was 5 to 10 percentage points lower on chopped dc than on ripple free dc. The chopped dc locked-rotor torque was approximately 1 to 3 percent greater than the ripple free dc torque for the same average current.
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CSIR Research Space (South Africa)
Grobler, Inus
2013-09-01
Full Text Available . The military specified DC-DC converters are applicable, spanning from 100 W handheld power managers up to 2 kW DC-DC battery chargers. Circuit layout high frequency effects as well as high frequency impedances of the power components were characterised...
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A New Sliding Mode Controller for DC/DC Converters in Photovoltaic Systems
Directory of Open Access Journals (Sweden)
M. Sarvi
2013-01-01
Full Text Available DC/DC converters are widely used in many industrial and electrical systems. As DC/DC converters are nonlinear and time-variant systems, the application of linear control techniques for the control of these converters is not suitable. In this paper, a new sliding mode controller is proposed as the indirect control method and compared to a simple direct control method in order to control a buck converter in photovoltaic applications. The solar arrays are dependent power sources with nonlinear voltage-current characteristics under different environmental conditions (insolation and temperature. From this point of view, the DC/DC converter is particularly suitable for the application of the sliding mode control in photovoltaic application, because of its controllable states. Simulations are performed in Matlab/Simulink software. The simulation results are presented for a step change in reference voltage and input voltage as well as step load variations. The simulations results of proposed method are compared with the conventional PID controller. The results show the good performance of the proposed sliding mode controller. The proposed method can be used for the other DC/DC converter.
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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...
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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...
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A DC-DC Conversion Powering Scheme for the CMS Phase-1 Pixel Upgrade
Feld, Lutz Werner; Marcel Friedrichs; Richard Hensch; Karpinski, Waclaw; Klein, Katja; Sammet, Jan Domenik; Wlochal, Michael
2012-01-01
The powering scheme of the CMS pixel detector will be described, and the performance of prototype DC-DC buck converters will be presented, including power efficiency, system tests with DC-DC converters and pixel modules, thermal management, reliability at low temperature, and studies of potential frequency locking betwe...
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78 FR 25685 - Magnuson-Stevens Act Provisions; Implementation of the Shark Conservation Act of 2010
2013-05-02
.... 111014628-3329-01] RIN 0648-BB54 Magnuson-Stevens Act Provisions; Implementation of the Shark Conservation... implement the provisions of the Shark Conservation Act of 2010 (SCA) and prohibit any person from removing any of the fins of a shark at sea, possessing shark fins on board a fishing vessel unless they are...
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Study on the Control Algorithm of Two-Stage DC-DC Converter for Electric Vehicles
Directory of Open Access Journals (Sweden)
Changhao Piao
2014-01-01
Full Text Available The fast response, high efficiency, and good reliability are very important characteristics to electric vehicles (EVs dc/dc converters. Two-stage dc-dc converter is a kind of dc-dc topologies that can offer those characteristics to EVs. Presently, nonlinear control is an active area of research in the field of the control algorithm of dc-dc converters. However, very few papers research on two-stage converter for EVs. In this paper, a fixed switching frequency sliding mode (FSFSM controller and double-integral sliding mode (DISM controller for two-stage dc-dc converter are proposed. And a conventional linear control (lag is chosen as the comparison. The performances of the proposed FSFSM controller are compared with those obtained by the lag controller. In consequence, the satisfactory simulation and experiment results show that the FSFSM controller is capable of offering good large-signal operations with fast dynamical responses to the converter. At last, some other simulation results are presented to prove that the DISM controller is a promising method for the converter to eliminate the steady-state error.
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Regulation of DC development and DC-mediated T-cell immunity via CISH
Miah, Mohammad Alam; Bae, Yong-Soo
2013-01-01
Cytokine inducible SH2-containing protein (CISH) plays a crucial role in type 1 dendritic cell (DC) development as well as in the DC-mediated activation of cytotoxic T lymphocytes (CTLs). CISH expression at late DC developmental stages shuts down the proliferation of DC progenitors by negatively regulating signal transducer and activator of transcription 5 (STAT5) and facilitates the differentiation of DCs into potent stimulators of CTLs.
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Regulation of DC development and DC-mediated T-cell immunity via CISH.
Miah, Mohammad Alam; Bae, Yong-Soo
2013-03-01
Cytokine inducible SH2-containing protein (CISH) plays a crucial role in type 1 dendritic cell (DC) development as well as in the DC-mediated activation of cytotoxic T lymphocytes (CTLs). CISH expression at late DC developmental stages shuts down the proliferation of DC progenitors by negatively regulating signal transducer and activator of transcription 5 (STAT5) and facilitates the differentiation of DCs into potent stimulators of CTLs.
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International Nuclear Information System (INIS)
Capobianco, Amedeo; Caruso, Tonino; Palombi, Laura; Peluso, Andrea
2013-01-01
Highlights: ► Mechanistic insights of the electro-induced Stevens rearrangement are provided. ► The reduction of PhCOCH 2 N + (CH 3 ) 2 CH 2 Ph is ascribed to a one-electron transfer process. ► An electrogenerated ammonium ylide has been detected by UV-spectroelectrochemistry. -- Abstract: The electrochemically-induced Stevens rearrangement of 2-(benzyldimethyl)ammonium acetophenone has been investigated by in situ UV–vis spectroelectrochemistry. Voltammetric analysis and absorption spectra recorded during the potentiostatic reduction indicate that the reaction proceeds via a one-electron transfer with a Platinum cathode and generation of an ammonium ylide intermediate
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Controlling DC-DC converters by chaos-based pulse width modulation to reduce EMI
International Nuclear Information System (INIS)
Li Hong; Zhang Bo; Li Zhong; Halang, Wolfgang A.; Chen Guanrong
2009-01-01
In this paper, periodic and chaotic behaviors of DC-DC converters under certain parametric conditions are simulated, experimentally verified, and analyzed. Motivated by the work of J.H.B. Deane and D.C. Hamill in 1996, where chaotic phenomena are useful in suppressing electromagnetic interference (EMI) by adjusting the parameters of the DC-DC converter and making it operate in chaos, a chaos-based pulse width modulation (CPWM) is proposed to distribute the harmonics of the DC-DC converters continuously and evenly over a wide frequency range, thereby reducing the EMI. The output waves and spectral properties of the EMI are simulated and analyzed as the carrier frequency or amplitude changes with regard to different chaotic maps. Simulation and experimental results are given to illustrate the effectiveness of the proposed CPWM, which provides a good example of applying chaos theory in engineering practice.
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Elimination of output voltage oscillations in DC-DC converter using PWM with PI controller
Directory of Open Access Journals (Sweden)
Sreenivasappa Veeranna Bhupasandra
2010-01-01
Full Text Available In this paper the SIMULINK model of a PWM controlled DC-DC converter is modeled using switching function concept to control the speed of the DC motor. The presence of the voltage oscillation cycles due to higher switching frequency in the DC-DC converter is identified. The effect of these oscillations on the output voltage of the converter, Armature current, Developed torque and Speed of the DC motor is analyzed. In order to minimize the oscillation cycles the PI controller is proposed in the PWM controller.
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Analysis of high voltage step-up nonisolated DC-DC boost converters
Alisson Alencar Freitas, Antônio; Lessa Tofoli, Fernando; Junior, Edilson Mineiro Sá; Daher, Sergio; Antunes, Fernando Luiz Marcelo
2016-05-01
A high voltage step-up nonisolated DC-DC converter based on coupled inductors suitable to photovoltaic (PV) systems applications is proposed in this paper. Considering that numerous approaches exist to extend the voltage conversion ratio of DC-DC converters that do not use transformers, a detailed comparison is also presented among the proposed converter and other popular topologies such as the conventional boost converter and the quadratic boost converter. The qualitative analysis of the coupled-inductor-based topology is developed so that a design procedure can be obtained, from which an experimental prototype is implemented to validate the theoretical assumptions.
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Common mode noise in three-level DC-DC converters
CSIR Research Space (South Africa)
Grobler, Inus
2009-09-01
Full Text Available that three-level buck DC-DC converters in general generate much lower common mode currents than conventional two-level buck converters. Further, reductions in common mode currents are achieved by using the improved three-level topologies that have been...
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DEFF Research Database (Denmark)
Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.
2009-01-01
Abstract-In this paper, an extended run time DC UPS system structure with fuel cell and supercapacitor is investigated. A wide input range bi-directional dc-dc converter is described along with the phase-shift modulation scheme and phase-shift with duty cycle control, in different modes. The deli......Abstract-In this paper, an extended run time DC UPS system structure with fuel cell and supercapacitor is investigated. A wide input range bi-directional dc-dc converter is described along with the phase-shift modulation scheme and phase-shift with duty cycle control, in different modes...
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DC-DC power converter research for Orbiter/Station power exchange
Ehsani, M.
1993-01-01
This project was to produce innovative DC-DC power converter concepts which are appropriate for the power exchange between the Orbiter and the Space Station Freedom (SSF). The new converters must interface three regulated power buses on SSF, which are at different voltages, with three fuel cell power buses on the Orbiter which can be at different voltages and should be tracked independently. Power exchange is to be bi-directional between the SSF and the Orbiter. The new converters must satisfy the above operational requirements with better weight, volume, efficiency, and reliability than is available from the present conventional technology. Two families of zero current DC-DC converters were developed and successfully adapted to this application. Most of the converters developed are new and are presented.
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Sliding-mode control of single input multiple output DC-DC converter
Zhang, Libo; Sun, Yihan; Luo, Tiejian; Wan, Qiyang
2016-10-01
Various voltage levels are required in the vehicle mounted power system. A conventional solution is to utilize an independent multiple output DC-DC converter whose cost is high and control scheme is complicated. In this paper, we design a novel SIMO DC-DC converter with sliding mode controller. The proposed converter can boost the voltage of a low-voltage input power source to a controllable high-voltage DC bus and middle-voltage output terminals, which endow the converter with characteristics of simple structure, low cost, and convenient control. In addition, the sliding mode control (SMC) technique applied in our converter can enhance the performances of a certain SIMO DC-DC converter topology. The high-voltage DC bus can be regarded as the main power source to the high-voltage facility of the vehicle mounted power system, and the middle-voltage output terminals can supply power to the low-voltage equipment on an automobile. In the respect of control algorithm, it is the first time to propose the SMC-PID (Proportion Integration Differentiation) control algorithm, in which the SMC algorithm is utilized and the PID control is attended to the conventional SMC algorithm. The PID control increases the dynamic ability of the SMC algorithm by establishing the corresponding SMC surface and introducing the attached integral of voltage error, which endow the sliding-control system with excellent dynamic performance. At last, we established the MATLAB/SIMULINK simulation model, tested performance of the system, and built the hardware prototype based on Digital Signal Processor (DSP). Results show that the sliding mode control is able to track a required trajectory, which has robustness against the uncertainties and disturbances.
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Low amplitude impact of PBX 9501: Modified Steven spigot gun tests
Energy Technology Data Exchange (ETDEWEB)
Idar, D.J.; Lucht, R.A.; Straight, J.W. [and others
1998-12-01
Low-velocity mechanical impact and subsequent high explosive (HE) reaction are of concern in credible accident scenarios involving the handling, transport, and storage of nuclear weapons. Using modified Steven spigot gun tests, the authors have investigated the high-explosive violent-reaction (HEVR) potential of PBX 9501 to low-amplitude insult. Reliable modeling predictions require that one identify the relevant parameters and behavioral responses that are key to the reaction mechanism(s) in PBX 9501. Additional efforts have been targeted at identifying relevant differences in the response between baseline and stockpile-aged PBX 9501 to low-velocity impacts.
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Síndrome de Stevens-Johnson: presentación de un caso
Fernández Brizuela, Ener de Jesús; Morales Díaz, Felicia
2011-01-01
Fundamento: el síndrome de Stevens-Johnson, también llamado eritema multiforme mayor, se caracteriza por una serie de lesiones cutáneas de diversa morfología, es una grave lesión en la cual están afectadas al menos dos membranas mucosas y la piel. La patogenia de esta enfermedad es desconocida aunque generalmente se considera que es provocada por una reacción de hipersensibilidad a drogas, infecciones y exposición a sustancias tóxicas. Caso clínico: esta afección fue diagnosticada en un niño ...
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Y-Source Boost DC/DC Converter for Distributed Generation
DEFF Research Database (Denmark)
Siwakoti, Yam P.; Loh, Poh Chiang; Blaabjerg, Frede
2015-01-01
This paper introduces a versatile Y-source boost dc/dc converter intended for distributed power generation, where high gain is often demanded. The proposed converter uses a Y-source impedance network realized with a tightly coupled three-winding inductor for high voltage boosting that is presently...
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SUBCONTRACT REPORT: DC-DC Converter for Fuel Cell and Hybrid Vehicles
Energy Technology Data Exchange (ETDEWEB)
Marlino, Laura D [ORNL; Zhu, Lizhi [Ballard Power Systems/Siemens VDO
2007-07-01
The goal of this project is to develop and fabricate a 5kW dc-dc converter with a baseline 14V output capability for fuel cell and hybrid vehicles. The major objectives for this dc-dc converter technology are to meet: Higher efficiency (92%); High coolant temperature,e capability (105 C); High reliability (15 Years/150,000miles); Smaller volume (5L); Lower weight (6kg); and Lower cost ($75/kW). The key technical challenge for these converters is the 105 C coolant temperatures. The power switches and magnetics must be designed to sustain these operating temperatures reliably, without a large cost/mass/volume penalty.
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Multi-level cascaded DC/DC converters for PV applications
Directory of Open Access Journals (Sweden)
Ahmed A.A. Hafez
2015-12-01
Full Text Available A robust multi-level cascaded DC/DC system for Photovoltaic (PV application is advised in this article. There are three PV generators, each is coupled to a half-bridge buck cell. Each PV-generator–buck-converter channel is controlled such that maximum power is captured independently under different irradiation and temperature levels. The system operation under normal and abnormal conditions was comprehensively investigated. Internal Model Control (IMC technique was adopted for tuning the controllers. An elaborate switching modulation strategy was used to reduce the current ripple and inductor size, while maintaining high efficiency. Annotative, simple and robust remedial strategies were proposed to mitigate different anticipated faults. Comprehensive simulation results in Matlab environment were illustrated for corroborating the performance of the advised cascaded DC/DC system under normal/abnormal conditions. The proposed system enjoys the merits of independency, reduced volumetric dimensions and improved efficiency. Furthermore, the system is inherently fault-tolerant.
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Development of a DC-DC conversion powering scheme for the CMS Phase-1 pixel upgrade
Feld, Lutz Werner; Karpinski, Waclaw; Klein, Katja; Lipinski, Martin; Preuten, Marius; Max Rauch; Rittich, David Michael; Sammet, Jan Domenik; Wlochal, Michael
2014-01-01
A novel powering scheme based on the DC-DC conversion technique will be exploited to power the CMS Phase-1 pixel detector. DC-DC buck converters for the CMS pixel project have been developed, based on the AMIS5 ASIC designed by CERN. The powering system of the Phase-1 pixel detector is described and the performance of the converter prototypes is detailed, including power efficiency, stability of the output voltage, shielding, and thermal management. Results from a test of the magnetic field tolerance of the DC-DC converters are reported. System tests with pixel modules using many components of the future pixel barrel system are summarized. Finally first impressions from a pre-series of 200 DC-DC converters are presented.
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Auxiliary resonant DC tank converter
Peng, Fang Z.
2000-01-01
An auxiliary resonant dc tank (ARDCT) converter is provided for achieving soft-switching in a power converter. An ARDCT circuit is coupled directly across a dc bus to the inverter to generate a resonant dc bus voltage, including upper and lower resonant capacitors connected in series as a resonant leg, first and second dc tank capacitors connected in series as a tank leg, and an auxiliary resonant circuit comprising a series combination of a resonant inductor and a pair of auxiliary switching devices. The ARDCT circuit further includes first clamping means for holding the resonant dc bus voltage to the dc tank voltage of the tank leg, and second clamping means for clamping the resonant dc bus voltage to zero during a resonant period. The ARDCT circuit resonantly brings the dc bus voltage to zero in order to provide a zero-voltage switching opportunity for the inverter, then quickly rebounds the dc bus voltage back to the dc tank voltage after the inverter changes state. The auxiliary switching devices are turned on and off under zero-current conditions. The ARDCT circuit only absorbs ripples of the inverter dc bus current, thus having less current stress. In addition, since the ARDCT circuit is coupled in parallel with the dc power supply and the inverter for merely assisting soft-switching of the inverter without participating in real dc power transmission and power conversion, malfunction and failure of the tank circuit will not affect the functional operation of the inverter; thus a highly reliable converter system is expected.
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Dc-To-Dc Converter Uses Reverse Conduction Of MOSFET's
Gruber, Robert P.; Gott, Robert W.
1991-01-01
In modified high-power, phase-controlled, full-bridge, pulse-width-modulated dc-to-dc converters, switching devices power metal oxide/semiconductor field-effect transistors (MOSFET's). Decreases dissipation of power during switching by eliminating approximately 0.7-V forward voltage drop in anti-parallel diodes. Energy-conversion efficiency increased.
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Development of a green mode DC/DC converter available to portable nuclear instrument
International Nuclear Information System (INIS)
Gao Feiyan; Wu Longxiong; Tan Wei; Tang Yaogeng
2010-01-01
A green mode DC/DC converter was developed which suitable to the portable nuclear instrument which is powered by battery and is sometime at stand-by mode. Some updated control approaches such as pseudo-resonant type power supply control and synchronous rectification were adopted to makethe DC/DC converter operate with low power consumption and high efficiency. The test results the battery can be prolonged with this converter. (authors)
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A Dual-Buck–Boost AC/DC Converter for DC Nanogrid With Three Terminal Outputs
DEFF Research Database (Denmark)
Wu, Weimin; Wang, Houqing; Liu, Yuan
2017-01-01
Due to the widely used dc characterized loads and more distributed power generation sources, the dc nanogrid becomes more and more popular, and it is seen as an alternative to the ac grid. For safety considerations, the dc nanogrid should provide reliable grounding for the residential loads...... such as the low-voltage ac power system. There are three typical grounding configurations for a dc nanogrid: the united grounding, the unidirectional grounding, and the virtual isolated grounding. Each grounding configuration has its own specifications to ac/dc converters. In this paper, a dual-buck-boost ac/dc...... converter for use in the united-grounding-configuration-based dc nanogrid with three terminal outputs is proposed. The working principle of this converter is presented in detail through analyzing the equivalent circuits. Experiments are carried out to verify the theoretical analysis....
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DESIGN OPTIMIZATION OF RESONANT DC-DC CONVERTERS
Belqasem Aljafari
2016-01-01
Resonant DC/DC converters are the class of converters, which have L-C resonant tank serving as a major part of the power conversion process. The fundamental concept of the resonant converter is that the circulating energy in an L-C resonant circuit is manageable by changing the operating frequency, and therefore the converter can condition the input power to the desired output voltage. The development in power conversion technology is steady demand for high power efficiency and high power den...
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High Voltage Coil Current Sensor for DC-DC Converters Employing DDCC
Directory of Open Access Journals (Sweden)
M. Drinovsky
2015-12-01
Full Text Available Current sensor is an integral part of every switching converter. It is used for over-current protection, regulation and in case of multiphase converters for balancing. A new high voltage current sensor for coil-based current sensing in DC-DC converters is presented. The sensor employs DDCC with high voltage input stage and gain trimming. The circuit has been simulated and implemented in 0.35 um BCD technology as part of a multiphase DC-DC converter where its function has been verified. The circuit is able to sustain common mode voltage on the input up to 40 V, it occupies 0.387*0.345 mm2 and consumes 3.2 mW typically.
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2013-06-17
.... 111014628-3329-01] RIN 0648-BB54 Magnuson-Stevens Act Provisions; Implementation of the Shark Conservation.... SUMMARY: NMFS published a proposed rule on May 2, 2013, to implement provisions of the Shark Conservation Act of 2010 (SCA) that prohibit any person from removing any of the fins of a shark at sea, possessing...
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2013-07-08
.... 111014628-3329-01] RIN 0648-BB54 Magnuson-Stevens Act Provisions; Implementation of the Shark Conservation... period. SUMMARY: NMFS published a proposed rule on May 2, 2013, to implement provisions of the Shark Conservation Act of 2010 (SCA) that prohibit any person from removing any of the fins of a shark at sea...
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Tandem catalytic allylic amination and [2,3]-Stevens rearrangement of tertiary amines.
Soheili, Arash; Tambar, Uttam K
2011-08-24
We have developed a catalytic allylic amination involving tertiary aminoesters and allylcarbonates, which is the first example of the use of tertiary amines as intermolecular nucleophiles in metal-catalyzed allylic substitution chemistry. This process is employed in a tandem ammonium ylide generation/[2,3]-rearrangement reaction, which formally represents a palladium-catalyzed Stevens rearrangement. Low catalyst loadings and mild reaction conditions are compatible with an unprecedented substrate scope for the ammonium ylide functionality, and products are generated in high yields and diastereoselectivities. Mechanistic studies suggested the reversible formation of an ammonium intermediate.
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On the modelling of linear-assisted DC-DC voltage regulators for photovoltaic solar energy systems
Martínez-García, Herminio; García-Vílchez, Encarna
2017-11-01
This paper shows the modelling of linear-assisted or hybrid (linear & switching) DC/DC voltage regulators. In this kind of regulators, an auxiliary linear regulator is used, which objective is to cancel the ripple at the output voltage and provide fast responses for load variations. On the other hand, a switching DC/DC converter, connected in parallel with the linear regulator, allows to supply almost the whole output current demanded by the load. The objective of this topology is to take advantage of the suitable regulation characteristics that series linear voltage regulators have, but almost achieving the high efficiency that switching DC/DC converters provide. Linear-assisted DC/DC regulators are feedback systems with potential instability. Therefore, their modelling is mandatory in order to obtain design guidelines and assure stability of the implemented power supply system.
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A Feedback Passivation Design for DC Microgrid and Its DC/DC Converters
Directory of Open Access Journals (Sweden)
Feifan Ji
2016-12-01
Full Text Available There are difficulties in analyzing the stability of microgrids since they are located on various network structures. However, considering that the network often consists of passive elements, the passivity theory is applied in this paper to solve the above-mentioned problem. It has been formerly shown that when the network is weakly strictly positive real (WSPR, the DC microgrid is stable if all interfaces between the microgrid and converters are made to be passive, which is called interface passivity. Then, the feedback passivation method is proposed for the controller design of various DC–DC converters to achieve the interface passivity. The interface passivity is different from the passivity of closed-loop systems on which the passivity based control (PBC concentrates. The feedback passivation design is detailed for typical buck converters and boost converters in terms of conditions that the controller parameters should satisfy. The theoretical results are verified by a hardware-in-loop real-time labotray (RTLab simulation of a DC microgrid with four generators.
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Test Results of Selected Commercial DC/DC Converters under Cryogenic Temperatures - A Digest
Patterson, Richard; Hammoud, Ahmad
2010-01-01
DC/DC converters are widely used in space power systems in the areas of power management and distribution, signal conditioning, and motor control. Design of DC/DC converters to survive cryogenic temperatures will improve the power system performance, simplify design, and reduce development and launch costs. In this work, the performance of nine COTS modular, low-tomedium power DC/DC converters was investigated under cryogenic temperatures. The converters were evaluated in terms of their output regulation, efficiency, and input and output currents. At a given temperature, these properties were obtained at various input voltages and at different load levels. A summary on the performance of the tested converters was given. More comprehensive testing and in-depth analysis of performance under long-term exposure to extreme temperatures are deemed necessary to establish the suitability of these and other devices for use in the harsh environment of space exploration missions.
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A Bidirectional Resonant DC-DC Converter Suitable for Wide Voltage Gain Range
DEFF Research Database (Denmark)
Shen, Yanfeng; Wang, Huai; Al-Durra, Ahmed
2018-01-01
This paper proposes a new bidirectional resonant dc-dc converter suitable for wide voltage gain range applications (e.g., energy storage systems). The proposed converter overcomes the narrow voltage gain range of conventional resonant dc-dc converters, and meanwhile achieves high efficiency...... losses. The operation principles and characteristics of the proposed converter are firstly analyzed in this paper. Then the analytical solutions for the voltage gain, soft-switching, and rms currents are derived, which facilitates the parameters design and optimization. Finally, the proposed topology...... and analysis are verified with experimental results obtained from a 1-kW converter prototype....
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International Nuclear Information System (INIS)
Nizami, Lance
2010-01-01
Norwich's Entropy Theory of Perception (1975-present) is a general theory of perception, based on Shannon's Information Theory. Among many bold claims, the Entropy Theory presents a truly astounding result: that Stevens' Law with an Index of 1, an empirical power relation of direct proportionality between perceived taste intensity and stimulus concentration, arises from theory alone. Norwich's theorizing starts with several extraordinary hypotheses. First, 'multiple, parallel receptor-neuron units' without collaterals 'carry essentially the same message to the brain', i.e. the rate-level curves are identical. Second, sensation is proportional to firing rate. Third, firing rate is proportional to the taste receptor's 'resolvable uncertainty'. Fourth, the 'resolvable uncertainty' is obtained from Shannon's Information Theory. Finally, 'resolvable uncertainty' also depends upon the microscopic thermodynamic density fluctuation of the tasted solute. Norwich proves that density fluctuation is density variance, which is proportional to solute concentration, all based on the theory of fluctuations in fluid composition from Tolman's classic physics text, 'The Principles of Statistical Mechanics'. Altogether, according to Norwich, perceived taste intensity is theoretically proportional to solute concentration. Such a universal rule for taste, one that is independent of solute identity, personal physiological differences, and psychophysical task, is truly remarkable and is well-deserving of scrutiny. Norwich's crucial step was the derivation of density variance. That step was meticulously reconstructed here. It transpires that the appropriate fluctuation is Tolman's mean-square fractional density fluctuation, not density variance as used by Norwich. Tolman's algebra yields a 'Stevens Index' of -1 rather than 1. As 'Stevens Index' empirically always exceeds zero, the Index of -1 suggests that it is risky to infer psychophysical laws of sensory response from information theory
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Y-source impedance-network-based isolated boost DC/DC converter
DEFF Research Database (Denmark)
Siwakoti, Yam P.; Town, Graham; Loh, Poh Chiang
2014-01-01
A dc-dc converter with very high voltage gain is proposed in this paper for any medium-power application requiring a high voltage boost with galvanic isolation. The proposed converter topology can be realized using only two switches. With this topology a very high voltage boost can be achieved even...... with a relatively low duty cycle of the switches, and the gain obtainable is presently not matched by any existing impedance network based converter operated at the same duty ratio. The proposed converter has a Y-source impedance network to boost the voltage at the intermediate dc-link side and a push......-pull transformer for square-wave AC inversion and isolation. The voltage-doubler rectifier provides a constant dc voltage at the output stage. A theoretical analysis of the converter is presented, supported by simulation and experimental results. A 250 W down-scaled prototype was implemented in the laboratory...
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Su, Gui-Jia
2003-06-10
A multilevel DC link inverter and method for improving torque response and current regulation in permanent magnet motors and switched reluctance motors having a low inductance includes a plurality of voltage controlled cells connected in series for applying a resulting dc voltage comprised of one or more incremental dc voltages. The cells are provided with switches for increasing the resulting applied dc voltage as speed and back EMF increase, while limiting the voltage that is applied to the commutation switches to perform PWM or dc voltage stepping functions, so as to limit current ripple in the stator windings below an acceptable level, typically 5%. Several embodiments are disclosed including inverters using IGBT's, inverters using thyristors. All of the inverters are operable in both motoring and regenerating modes.
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Stability analysis of a high-step-Up DC grid-connected two-stage boost DC-DC converter
Directory of Open Access Journals (Sweden)
El Aroudi A.
2014-01-01
Full Text Available High conversion ratio switching converters are used whenever there is a need to step-up dc source voltage level to a much higher output dc voltage level such as in photovoltaic systems, telecommunications and in some medical applications. A simple solution for achieving this high conversion ratio is by cascading different stages of dc-dc boost converters. The individual converters in such a cascaded system are usually designed separately applying classical design criteria. However these criteria may not be applicable for the complete cascaded system . This paper first presents a glimpse on the bifurcation behavior that a cascade connection of two boost converters can exhibit. It is shown that the desired periodic orbit can undergo period doubling leading to subharmonic oscillations and chaotic regimes. Then, in order to simplify the analysis the second stage is considered as constant current sink and design-oriented analysis is carried out to obtain stability boundaries in the parameter space by taking into account slope interactions between the state variables in the two-different stages.
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Directory of Open Access Journals (Sweden)
Eka Prasetyono
2015-09-01
Full Text Available Bidirectional DC-DC converter is needed in the energy storage system. The converter topology used in this paper was a non-isolated bidirectional DC-DC buck-boost converter. This converter worked in two ways, which the charging mode stored energy into battery when load current was less than nominal main DC current (set point and discharging mode transferred energy from battery to the load when its current exceeded set point value. Both of these modes worked automatically according to the load current. The charging and discharging currents were controlled by fuzzy logic controller which was implemented on microcontroller ARM Cortex-M4F STM32F407VG. This paper compares two types of fuzzy membership function (triangular and sigmoid in controlling bidirectional DC-DC converter. The results showed that fuzzy logic controller with triangle membership function and sigmoid as control bidirectional DC-DC converter had no significant different response, both had an average error for charging and discharging process under 4% with ripple current on the main DC bus around 0.5%. The computing time of program for fuzzy logic controller with triangular membership functions had 19.01% faster than sigmoid, and fuzzy logic computation time on a microcontroller with hardware floating point was 60% faster than software floating point.
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Digitally intensive DC-DC converter for extreme space environments, Phase II
National Aeronautics and Space Administration — The Space Micro-Arizona State University (ASU) team will develop an all-digitally controlled, wide temperature range point-of-load switch-mode DC-DC regulator core...
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Zero-voltage DC/DC converter with asymmetric pulse-width modulation for DC micro-grid system
Lin, Bor-Ren
2018-04-01
This paper presents a zero-voltage switching DC/DC converter for DC micro-grid system applications. The proposed circuit includes three half-bridge circuit cells connected in primary-series and secondary-parallel in order to lessen the voltage rating of power switches and current rating of rectifier diodes. Thus, low voltage stress of power MOSFETs can be adopted for high-voltage input applications with high switching frequency operation. In order to achieve low switching losses and high circuit efficiency, asymmetric pulse-width modulation is used to turn on power switches at zero voltage. Flying capacitors are used between each circuit cell to automatically balance input split voltages. Therefore, the voltage stress of each power switch is limited at Vin/3. Finally, a prototype is constructed and experiments are provided to demonstrate the circuit performance.
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A Fixed-Frequency Bidirectional Resonant DC-DC Converter Suitable for Wide Voltage Gain Range
DEFF Research Database (Denmark)
Shen, Yanfeng; Wang, Huai; Blaabjerg, Frede
2017-01-01
This paper proposes a new bidirectional resonant dc-dc converter suitable for wide voltage gain range applications (e.g., energy storage systems). The proposed converter overcomes the narrow voltage gain range of conventional resonant DC-DC converters, and meanwhile achieves high efficiency...... and characteristics of the proposed converter are analyzed. Finally, a 1-kW converter prototype is built and the experimental results verify the theoretical analyses....
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Pulse-width modulated DC-DC power converters
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,
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Rufini, Sara; Ciccacci, Cinzia; Politi, Cristina; Giardina, Emiliano; Novelli, Giuseppe; Borgiani, Paola
2015-11-01
Stevens-Johnson syndrome and toxic epidermal necrolysis are severe, life-threatening drug reactions involving skin and membranes mucous, which are associated with significant morbidity and mortality and triggered, especially by drug exposure. Different studies have demonstrated that drug response is a multifactorial character and that the interindividual variability in this response depends on both environmental and genetic factors. The last ones have a relevant significance. In fact, the identification of new specific genetic markers involved in the response to drugs, will be of great utility to establish a more personalized therapeutic approach and to prevent the appearance of these adverse reactions. In this review, we summarize recent progresses in the Pharmacogenetics studies related to Stevens-Johnson syndrome/toxic epidermal necrolysis reporting the major genetic factors identified in the last years as associated with the disease and highlighting the use of some of these genomic variants in the clinical practice.
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Digitally intensive DC-DC converter for extreme space environments, Phase I
National Aeronautics and Space Administration — The Space Micro Arizona State University (ASU) team will develop an all-digitally controlled, wide temperature range point-of-load switch-mode DC-DC regulator core...
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DC Voltage Droop Control Implementation in the AC/DC Power Flow Algorithm: Combinational Approach
DEFF Research Database (Denmark)
Akhter, F.; Macpherson, D.E.; Harrison, G.P.
2015-01-01
of operational flexibility, as more than one VSC station controls the DC link voltage of the MTDC system. This model enables the study of the effects of DC droop control on the power flows of the combined AC/DC system for steady state studies after VSC station outages or transient conditions without needing...... to use its complete dynamic model. Further, the proposed approach can be extended to include multiple AC and DC grids for combined AC/DC power flow analysis. The algorithm is implemented by modifying the MATPOWER based MATACDC program and the results shows that the algorithm works efficiently....
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High-Voltage DC-DC Converter Topology for PV Energy Utilization - Investigation and Implementation
DEFF Research Database (Denmark)
Sanjeevikumar, Padmanaban; Blaabjerg, Frede; Wheeler, Patrick
2017-01-01
This paper exploited the utilization of photovoltaic (PV) energy system with high-voltage (HV) output DC-DC converter. Classical boost converters are used for both renewable energy integration and HV applications, but limited by reducing output/efficiency in performance. Moreover, as parasitic...... elements suppress the power transfer ratio, converter needs to maximize the PV energy utilization. This investigation study focused to include additional parasitic elements (voltage-lift technique) to a standard DC-DC buck converter and to overcome all the above drawbacks to maximize the PV power...
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Computer Simulation of Phase Shifted Series Resonant DC to DC Converter
Directory of Open Access Journals (Sweden)
P. PARVATHY
2016-01-01
Full Text Available This paper deals with digital simulation of phase shifted series resonant DC to DC converter using Matlab Simulink. The Simulink models for open loop and closed loop systems are developed and they are used for simulation studies. This converter is capable of producing ripple free DC output. Switching losses and switching stresses are reduced by using soft switching. This converter has advantages like high power density and low switching losses. Theoretical predictions are well supported by the simulation results.
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Power flow analysis for DC voltage droop controlled DC microgrids
DEFF Research Database (Denmark)
Li, Chendan; Chaudhary, Sanjay; Dragicevic, Tomislav
2014-01-01
This paper proposes a new algorithm for power flow analysis in droop controlled DC microgrids. By considering the droop control in the power flow analysis for the DC microgrid, when compared with traditional methods, more accurate analysis results can be obtained. The algorithm verification is ca...
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Light weight, high power, high voltage dc/dc converter technologies
Kraus, Robert; Myers, Ira; Baumann, Eric
1990-01-01
Power-conditioning weight reductions by orders of magnitude will be required to enable the megawatt-power-level space systems envisioned by the Strategic Defense Initiative, the Air Force, and NASA. An interagency program has been initiated to develop an 0.1-kg/kW dc/dc converter technology base for these future space applications. Three contractors are in the first phase of a competitive program to develop a megawatt dc/dc converter. Researchers at NASA Lewis Research Center are investigating innovative converter topology control. Three different converter subsystems based on square wave, resonant, and super-resonant topologies are being designed. The components required for the converter designs cover a wide array of technologies. Two different switches, one semiconductor and the other gas, are under development. Issues related to thermal management and material reliability for inductors, transformers, and capacitors are being investigated in order to maximize power density. A brief description of each of the concepts proposed to meet the goals of this program is presented.
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Digital peak current mode control with adaptive slope compensation for DC-DC converters
DEFF Research Database (Denmark)
Andersen, Karsten Holm; Nymand, Morten
2017-01-01
performance and stability of current mode control. The presented method adapt to DC-DC converter operating conditions by estimating the rising and falling inductor current slopes, to apply a current slope compensation value to obtain a constant quality factor. The experimental results verifies the theoretical......This paper presents an adaptive slope compensation method for peak current mode control of digital controlled DC-DC converters, which controls the quality factor of the complex conjugated poles at half the switching frequency. Using quality factor control enables optimization of the dynamic...
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DC-Link Compensation Method for Slim DC Link Drives Fed by Soft Grid
DEFF Research Database (Denmark)
Mathe, Laszlo; Rosendahl Andersen, Henrik; Lazar, Radu
2010-01-01
Slim DC-link PWM (AC) drives for lowperformance applications are emerging on the market. Such drives equipped with a small DC-link capacitance exhibit instability tendencies, if installed on a soft line, giving a degraded performance. The total harmonic distortion (THD) and the partially weighted...... harmonic distortion (PWHD) of the line current are degraded, if resonance between the line impedance and the DC-link capacitance occurs. Likewise, the motor performance is affected negatively giving extra torque ripple, vibration and acoustic-noise emission. This paper proposes a novel DC-link compensation...
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High-power three-port three-phase bidirectional DC-DC converter
Tao, H.; Duarte, J.L.; Hendrix, M.A.M.
2007-01-01
This paper proposes a three-port three-phase bidirectional dc-dc converter suitable for high-power applications. The converter combines a slow primary source and a fast storage to power a common load (e.g., an inverter). Since this type of system is gaining popularity in sustainable energy
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Precharge strategies for isolated modular DC-DC converters under two different start-up conditions
DEFF Research Database (Denmark)
Zhang, Yi; Wang, Huai; Li, Binbin
2017-01-01
The isolated modular DC-DC converter (IMDCC) is a new topology designed to connect high-voltage direct current (HVDC) lines with different voltage levels, which ties two DC grids by using two modular multilevel converters (MMCs) via a medium-frequency transformer. Due to the large value of capaci......The isolated modular DC-DC converter (IMDCC) is a new topology designed to connect high-voltage direct current (HVDC) lines with different voltage levels, which ties two DC grids by using two modular multilevel converters (MMCs) via a medium-frequency transformer. Due to the large value...... of capacitance in the IMDCC, proper precharge strategies before the start-up are significant for the safety and reliability of the whole system. This paper presents two closed-loop precharge control strategies to fully charge the sub-module (SM) capacitors of the IMDCC, considering two different start...
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Modeling and analysis of fractional order DC-DC converter.
Radwan, Ahmed G; Emira, Ahmed A; AbdelAty, Amr M; Azar, Ahmad Taher
2017-07-11
Due to the non-idealities of commercial inductors, the demand for a better model that accurately describe their dynamic response is elevated. So, the fractional order models of Buck, Boost and Buck-Boost DC-DC converters are presented in this paper. The detailed analysis is made for the two most common modes of converter operation: Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM). Closed form time domain expressions are derived for inductor currents, voltage gain, average current, conduction time and power efficiency where the effect of the fractional order inductor is found to be strongly present. For example, the peak inductor current at steady state increases with decreasing the inductor order. Advanced Design Systems (ADS) circuit simulations are used to verify the derived formulas, where the fractional order inductor is simulated using Valsa Constant Phase Element (CPE) approximation and Generalized Impedance Converter (GIC). Different simulation results are introduced with good matching to the theoretical formulas for the three DC-DC converter topologies under different fractional orders. A comprehensive comparison with the recently published literature is presented to show the advantages and disadvantages of each approach. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.
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Magnetically coupled high-gain Y-source isolated DC/DC converter
DEFF Research Database (Denmark)
Siwakoti, Yam P.; Loh, Poh Chiang; Blaabjerg, Frede
2014-01-01
A new form of magnetically coupled DC/DC converter is proposed for medium power applications (250 W to 2 kW), requiring a high-voltage gain, short inductive charging time and galvanic isolation. The proposed converter can be realised using a unique Y-source impedance network and a two-switch push...
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A high voltage ratio and low ripple interleaved DC-DC converter for fuel cell applications.
Chang, Long-Yi; Chao, Kuei-Hsiang; Chang, Tsang-Chih
2012-01-01
This paper proposes a high voltage ratio and low ripple interleaved boost DC-DC converter, which can be used to reduce the output voltage ripple. This converter transfers the low DC voltage of fuel cell to high DC voltage in DC link. The structure of the converter is parallel with two voltage-doubler boost converters by interleaving their output voltages to reduce the voltage ripple ratio. Besides, it can lower the current stress for the switches and inductors in the system. First, the PSIM software was used to establish a proton exchange membrane fuel cell and a converter circuit model. The simulated and measured results of the fuel cell output characteristic curve are made to verify the correctness of the established simulation model. In addition, some experimental results are made to validate the effectiveness in improving output voltage ripple of the proposed high voltage ratio interleaved boost DC-DC converters.
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Directory of Open Access Journals (Sweden)
Wolfgang Heuer
2012-08-01
Full Text Available Abstract It is self-evident that events of the past are bound to places and acting people, they are playing a decisive role for memory and history. Meaning and importance of places and actions in the past depend on their contexts and each change inevitably also changes the meaning of the events itself. I would like to demonstrate some of the consequences of such a change by comparing Hannah Arendt’s “Eichmann in Jerusalem“ with Steven Spielberg’s “Schindler’s List“ who decontextualized a factual story and thus changed places and acting people. But before doing this, I would like to emphasize the importance which places and acting people play for memory and history with some perhaps unusual remarks. They refer to the official European history and politics which seem to be marked by the absence of places and acting people.Keywords: Eichmann in Jerusalem, Hannah Arendt, Schindler’s List, Steven SpielbergResumo É autoevidente que acontecimentos do passado estão condicionados a lugares e a pessoas atuantes, que têm papel fundamental na memória e na história. O significado e a importância de lugares e de ações do passado dependem de seu contexto e cada mudança sua inevitavelmente altera também os próprios acontecimentos. Eu gostaria de demonstrar algumas das consequências de tal mudança comparando “Eichmann em Israel”, de Hannah Arendt com “A Lista de Schindler”, de Steven Spielberg, que descontextualizou uma história real e, assim, modificou lugares e pessoas de atuação. Mas antes disso, eu gostaria de enfatizar a importância que lugares e pessoas atuantes têm a memória e na história com alguns comentários talvez inusitados. Eles fazem referência à História oficial e à política da Europa que parecem ser marcados pela ausência de lugares e de pessoas de atuação marcante.Palavras-chaves: Eichmann em Israel, Hannah Arendt, Lista de Schindler, Steven Spielberg
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Mycoplasma pneumoniae-Induced-Stevens Johnson Syndrome: Rare Occurrence in an Adult Patient
Directory of Open Access Journals (Sweden)
Samad Rasul
2012-01-01
Full Text Available Stevens-Johnson syndrome (SJS is an uncommon occurrence in Mycoplasma pneumoniae (M. pneumoniae infection (1–5% and has been mainly reported in children and young adults. We present a case of SJS in a 32-year-old male induced by M. pneumoniae infection. This patient presented with fever, cough, and massive occupation of mucus membranes with swelling, erythema, and necrosis accompanied by a generalized cutaneous rash. He clinically responded after treatment with antibiotics and IVIG. SJS is usually a drug-induced condition; however, M. pneumoniae is the commonest infectious cause and should be considered in the differential diagnosis.
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DC Rocks! Using Place-Based Learning to Introduce Washington DC's K-12 Students to the Geosciences
Mayberry, G. C.; Mattietti, G. K.
2017-12-01
The Washington DC area has interesting geology and a multitude of agencies that deal with the geosciences, yet K-12 public school students in DC, most of whom are minorities, have limited exposure to the geosciences. Geoscience agencies in the DC area have a unique opportunity to address this by introducing the geosciences to local students who otherwise may not have such an opportunity, by highlighting the geology in the students' "backyard," and by leveraging partnerships among DC-based geoscience-related agencies. The USGS and George Mason University are developing a project called DC Rocks, which will give DC's students an exciting introduction into the world of geoscience with place-based learning opportunities that will make geoscience relevant to their lives and their futures. Both the need in DC and the potential for lasting impact are great; the geosciences have the lowest racial diversity of all the science, technology, engineering, and math (STEM) fields, 89% of students in DC public schools are minorities, and there is no dedicated geoscience curriculum in DC. DC Rocks aims to give these students early exposure to the earth sciences, and encourage them to consider careers in the profession. DC Rocks will work with partner agencies to apply several methods that are recommended by researchers to increase the participation of minority students in the geosciences, including providing profoundly positive experiences that spark interest in the geosciences (Levine et al., 2007); increasing students' sense of belonging in the geosciences (Huntoon, et al, 2016); and place-based teaching practices that emphasize the study of local sites (Semken, 2005), such as DC's Rock Creek Park. DC Rocks will apply these methods by coordinating local geoscientists and resources to provide real-world examples of the geosciences' impact on students' lives. Through the DC Rocks website, educators will be able to request geoscience-related resources such as class presentations by
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Radiated electromagnetic emissions of DC-DC converters
International Nuclear Information System (INIS)
Feld, L; Jussen, R; Karpinski, W; Klein, K; Sammet, J; Wlochal, M
2010-01-01
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.
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Modeling, Analysis and Control of Different DC-DC Converter Topologies for Photo Voltaic Emulator
Directory of Open Access Journals (Sweden)
Mohammad Tauquir Iqbal
2016-05-01
Full Text Available This paper presents the modeling, analysis and control of different DC-DC converter topologies to emulate the photovoltaic (PV system. A PV emulator is basically a DC-DC converter having same electrical characteristics that of solar PV panel. The emulator helps to achieve real characteristics of PV system in a better way in an environment where using actual PV systems can produce inconsistent results due to variation in weather conditions. The paper describes different types of DC-DC converters like buck, Resonant and Quasi Resonant Converter. The complete system is modelled in MATLAB® Simulink SimPowerSystem software package. The Simulation results obtained from the MATLAB® Simulink SimPowerSystem software package for different topologies under steady and dynamic conditions are analyzed and presented. An evaluation table is also presented at the end of the paper, presenting the effectiveness of each topology.
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Crapo, Alan D.; Lloyd, Jerry D.
1991-03-01
Two motors have been designed and built for use with high-temperature superconductor (HTSC) materials. They are a homopolar dc motor that uses HTSC field windings and a brushless dc motor that uses bulk HTSC materials to trap flux in steel rotor poles. The HTSC field windings of the homopolar dc motor are designed to operate at 1000 A/sq cm in a 0.010-T field. In order to maximize torque in the homopolar dc motor, an iron magnetic circuit with small air gaps gives maximum flux for minimum Ampere turns in the field. A copper field winding version of the homopolar dc motor has been tested while waiting for 575 A turn HTSC coils. The trapped flux brushless dc motor has been built and is ready to test melt textured bulk HTSC rings that are currently being prepared. The stator of the trapped flux motor will impress a magnetic field in the steel rotor poles with warm HTSC bulk rings. The rings are then cooled to 77 K to trap the flux in the rotor. The motor can then operate as a brushless dc motor.
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Differential Mode EMI Filter Design for Isolated DC-DC Boost Converter
DEFF Research Database (Denmark)
Makda, Ishtiyaq Ahmed; Nymand, Morten
2014-01-01
A Differential Mode EMI filter for a low input voltage high-current isolated dc-dc boost converter is designed and presented in this paper. The primary side Differential Mode noise voltage is low due to the high transformer turn ratio, however, the input current is very high and since the EMI limit...... also does not change for such converters, it requires greatly optimized design approach for the filter including the correct sizing of the filter components. A complete analytical filter design process is carried out such a way that the Differential Mode noise voltage source in the converter...... is identified first. The DM noise model is then established and based on the harmonic analysis of the noise source voltage waveform, the complete Differential Mode EMI filter, including the filter resonance damping branch, is designed for a 3kW isolated dc-dc boost converter. The noise model and its theoretical...
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Current Mode Control for LLC Series Resonant DC-to-DC Converters
Directory of Open Access Journals (Sweden)
Jinhaeng Jang
2015-06-01
Full Text Available Conventional voltage mode control only offers limited performance for LLC series resonant DC-to-DC converters experiencing wide variations in operational conditions. When the existing voltage mode control is employed, the closed-loop performance of the converter is directly affected by unavoidable changes in power stage dynamics. Thus, a specific control design optimized at one particular operating point could become unacceptable when the operational condition is varied. This paper presents a new current mode control scheme which could consistently provide good closed-loop performance for LLC resonant converters for the entire operational range. The proposed control scheme employs an additional feedback from the current of the resonant tank network to overcome the limitation of the existing voltage mode control. The superiority of the proposed current mode control over the conventional voltage mode control is verified using an experimental 150 W LLC series resonant DC-to-DC converter.
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Application handbook for a Standardized Control Module (SCM) for DC-DC converters, volume 1
Lee, F. C.; Mahmoud, M. F.; Yu, Y.
1980-04-01
The standardized control module (SCM) was developed for application in the buck, boost and buck/boost DC-DC converters. The SCM used multiple feedback loops to provide improved input line and output load regulation, stable feedback control system, good dynamic transient response and adaptive compensation of the control loop for changes in open loop gain and output filter time constraints. The necessary modeling and analysis tools to aid the design engineer in the application of the SCM to DC-DC Converters were developed. The SCM functional block diagram and the different analysis techniques were examined. The average time domain analysis technique was chosen as the basic analytical tool. The power stage transfer functions were developed for the buck, boost and buck/boost converters. The analog signal and digital signal processor transfer functions were developed for the three DC-DC Converter types using the constant on time, constant off time and constant frequency control laws.
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Application handbook for a Standardized Control Module (SCM) for DC-DC converters, volume 1
Lee, F. C.; Mahmoud, M. F.; Yu, Y.
1980-01-01
The standardized control module (SCM) was developed for application in the buck, boost and buck/boost DC-DC converters. The SCM used multiple feedback loops to provide improved input line and output load regulation, stable feedback control system, good dynamic transient response and adaptive compensation of the control loop for changes in open loop gain and output filter time constraints. The necessary modeling and analysis tools to aid the design engineer in the application of the SCM to DC-DC Converters were developed. The SCM functional block diagram and the different analysis techniques were examined. The average time domain analysis technique was chosen as the basic analytical tool. The power stage transfer functions were developed for the buck, boost and buck/boost converters. The analog signal and digital signal processor transfer functions were developed for the three DC-DC Converter types using the constant on time, constant off time and constant frequency control laws.
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Geetha, A.; Subramani, C.; Thamizh Thentral, T. M.; Krithika, V.; Usha, S.
2018-04-01
Non isolated Bidirectional DC-DC Converter (NIBDDC) is a good interface between DC source and inverter Fed induction motor drive. This paper deals with comparison between open loop and PI controlled Bidirectional DC to DC Converter Inverter System (BDDCIS). The modelling and control of BDDC is becomes an important issue. Open loop BDDCIS and closed loop PI controlled BDDCIS are designed, modelled and simulated using Matlab- simulink and their results are presented. The investigations indicate superior performance of PI controlled BDDCIS. The proposed BDDCIS has advantages like bidirectional power transfer ability, reduced hardware count and improved dynamic response.
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Application of Distributed DC/DC Electronics in Photovoltaic Systems
Kabala, Michael
In a typical residential, commercial or utility grade photovoltaic (PV) system, PV modules are connected in series and in parallel to form an array that is connected to a standard DC/AC inverter, which is then connected directly to the grid. This type of standard installation; however, does very little to maximize the energy output of the solar array if certain conditions exist. These conditions could include age, temperature, irradiance and other factors that can cause mismatch between PV modules in an array that severely cripple the output power of the system. Since PV modules are typically connected in series to form a string, the output of the entire string is limited by the efficiency of the weakest module. With PV module efficiencies already relatively low, it is critical to extract the maximum power out of each module in order to make solar energy an economically viable competitor to oil and gas. Module level DC/DC electronics with maximum power point (MPP) tracking solves this issue by decoupling each module from the string in order for the module to operate independently of the geometry and complexity of the surrounding system. This allows each PV module to work at its maximum power point by transferring the maximum power the module is able to deliver directly to the load by either boosting (stepping up) the voltage or bucking (stepping down) the voltage. The goal of this thesis is to discuss the development of a per-module DC/DC converter in order to maximize the energy output of a PV module and reduce the overall cost of the system by increasing the energy harvest.
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Quasiperiodicity and Torus Breakdown in a Power Electronic DC/DC Converter
DEFF Research Database (Denmark)
Zhusubaliyev, Zhanybai; Soukhoterin, Evgeniy; Mosekilde, Erik
2007-01-01
This paper discusses the mechanisms of torus formation and torus destruction in a dc/dc converter with relay control and hysteresis. We establish a chart of the dynamical modes in the input voltage versus load resistance parameter plane. This chart displays several different torus bifurcations...
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DC Distribution Systems and Microgrids
DEFF Research Database (Denmark)
Dragicevic, Tomislav; Anvari-Moghaddam, Amjad; Quintero, Juan Carlos Vasquez
2017-01-01
summarized. Due to its attractive characteristics in terms of compliance with modern generation, storage and electronic load technologies, high reliability and current carrying capacity, as well as simple control, DC systems are already an indispensable part of power systems. Moreover, the existing......A qualitative overview of different hardware topologies and control systems for DC MGs has been presented in this chapter. Some challenges and design considerations of DC protections systems have also been discussed. Finally, applications of DC MGs in emerging smart grid applications have been...... challenges such as protection issues will be effectively resolved in the near future due to fast progress of semiconductor technology which is a key enabler cheap and reliable future DC solid-state protection systems. Therefore, it is the view of the author that more and more DC systems will appear...
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Analysis of the Coupling Behavior of PEM Fuel Cells and DC-DC Converters
Directory of Open Access Journals (Sweden)
Achim Kienle
2009-03-01
Full Text Available The connection between PEM fuel cells and common DC-DC converters is examined. The analysis is model-based and done for boost, buck and buck-boost converters. In a first step, the effect of the converter ripples upon the PEM fuel cell is shown. They introduce oscillations in the fuel cell. Their appearance is explained, discussed and possibilities for their suppression are given. After that, the overall behaviors of the coupled fuel cell-converter systems are analyzed. It is shown, that neither stationary multiplicities nor oscillations can be introduced by the couplings and therefore separate control approaches for both the PEMFC and the DC-DC converters are applicable.
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Single Event Burnout in DC-DC Converters for the LHC Experiments
Energy Technology Data Exchange (ETDEWEB)
Claudio H. Rivetta et al.
2001-09-24
High voltage transistors in DC-DC converters are prone to catastrophic Single Event Burnout in the LHC radiation environment. This paper presents a systematic methodology to analyze single event effects sensitivity in converters and proposes solutions based on de-rating input voltage and output current or voltage.
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Area-Efficiency Trade-Offs in Integrated Switched-Capacitor DC-DC Converters
DEFF Research Database (Denmark)
Spliid, Frederik Monrad; Larsen, Dennis Øland; Knott, Arnold
2016-01-01
This paper analyzes the relationship between efficiency and chip area in a fully integrated switched capacitor voltage divider dc-dc converter implemented in 180nm-technology and a 1/2 topology. A numerical algorithm for choosing the optimal sizes of individual components, in terms of power loss...
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Egr2 induced during DC development acts as an intrinsic negative regulator of DC immunogenicity.
Miah, Mohammad Alam; Byeon, Se Eun; Ahmed, Md Selim; Yoon, Cheol-Hee; Ha, Sang-Jun; Bae, Yong-Soo
2013-09-01
Early growth response gene 2 (Egr2), which encodes a zinc finger transcription factor, is rapidly and transiently induced in various cell types independently of de novo protein synthesis. Although a role for Egr2 is well established in T-cell development, Egr2 expression and its biological function in dendritic cells (DCs) have not yet been described. Here, we demonstrate Egr2 expression during DC development, and its role in DC-mediated immune responses. Egr2 is expressed in the later stage of DC development from BM precursor cells. Even at steady state, Egr2 is highly expressed in mouse splenic DCs. Egr2-knockdown (Egr2-KD) DCs showed increased levels of major histocompatability complex (MHC) class I and II and co-stimulatory molecules, and enhanced antigen uptake and migratory capacities. Furthermore, Egr2-KD abolished SOCS1 expression and signal transducer and activator of transcription 5 (STAT5) activation during DC development, probably resulting in the enhancement of IL-12 expression and Th1 immunogenicity of a DC vaccine. DC-mediated cytotoxic T lymphocyte (CTL) activation and antitumor immunity were significantly enhanced by Egr2-KD, and impaired by Egr2 overexpression in antigen-pulsed DC vaccines. These data suggest that Egr2 acts as an intrinsic negative regulator of DC immunogenicity and can be an attractive molecular target for DC vaccine development. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Impact of DC link control strategies on the power-flow convergence of integrated AC–DC systems
Directory of Open Access Journals (Sweden)
Shagufta Khan
2016-03-01
Full Text Available For the power-flow solution of integrated AC–DC systems, five quantities are required to be solved per converter, against three independent equations available. These three equations consist of two basic converter equations and one DC network equation, corresponding to each converter. Thus, for solution, two additional equations are required. These two equations are derived from the control specifications adopted for the DC link. Depending on the application, several combinations of valid control specifications are possible. A set of valid control specifications constitutes a control strategy. It is observed that the control strategy adopted for the DC link strongly affects the power-flow convergence of integrated AC–DC systems. This paper investigates how different control strategies affect the power flow convergence of integrated AC–DC systems. Sequential method is used to solve the DC variables in the Newton Raphson (NR power flow model. Seven typical control strategies have been taken into consideration. This is validated by numerous case studies carried out with multiple DC links incorporated in the IEEE 118-bus and 300-bus test systems.
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Burkhart, Keith K.; Abernethy, Darrell; Jackson, David
2015-01-01
Drug features that are associated with Stevens-Johnson syndrome (SJS) have not been fully characterized. A molecular target analysis of the drugs associated with SJS in the FDA Adverse Event Reporting System (FAERS) may contribute to mechanistic insights into SJS pathophysiology. The publicly available version of FAERS was analyzed to identify disproportionality among the molecular targets, metabolizing enzymes, and transporters for drugs associated with SJS. The FAERS in-house version was al...
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Investigation of DC-DC Boost Converter for Reliability of Operational Planning
DEFF Research Database (Denmark)
Khazraj, Hesam; Ashouri, Mani; Silva, Filipe Miguel Faria da
2018-01-01
of the interests related to reliability is the power semiconductor switches, which are the most vulnerable elements. The failure of one-power switches can reduce the system reliability. Interleaved technique for DC-DC converters is a redundant strategy to improve the reliability, but at the cost of increasing...
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Erythema multiforme and Stevens-Johnson syndrome following radiotherapy
International Nuclear Information System (INIS)
Yoshitake, Tadamasa; Nakamura, Katsumasa; Shioyama, Yoshiyuki
2007-01-01
Erythema multiforme (EM) and Stevens-Johnson syndrome (SJS) are thought to be hypersensitivity syndromes with various causes, and radiotherapy might be one of the causes of these syndromes. We herein report two cases of EM/SJS following radiotherapy. The first case was a 63-year-old woman with breast cancer. At the end of postoperative radiotherapy with 60 Gy, severe pruritic erythema appeared in the irradiated area and spread over the whole body. She was diagnosed with EM by a skin biopsy. The second case was a 77-year-old woman with uterine cervical cancer who underwent postoperative radiotherapy. At a dose of 30.6 Gy, pruritic redness appeared in the irradiated area and the precordial region, and it became widespread rapidly with polymorphic transformation. Although without any histological confirmation, SJS was strongly suspected because of her pruritic conjunctivitis. Because both patients were given medicines during irradiation, radiotherapy may not be the only cause of EM/SJS. However, it should be noted that radiotherapy might trigger EM/SJS. (author)
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Comparison of solar panel cooling system by using dc brushless fan and dc water
International Nuclear Information System (INIS)
Irwan, Y M; Leow, W Z; Irwanto, M; M, Fareq; Hassan, S I S; Amelia, A R; Safwati, I
2015-01-01
The purpose of this article is to discuss comparison of solar panel cooling system by using DC brushless fan and DC water pump. Solar photovoltaic (PV) power generation is an interesting technique to reduce non-renewable energy consumption and as a renewable energy. The temperature of PV modules increases when it absorbs solar radiation, causing a decrease in efficiency. A solar cooling system is design, construct and experimentally researched within this work. To make an effort to cool the PV module, Direct Current (DC) brushless fan and DC water pump with inlet/outlet manifold are designed for constant air movement and water flow circulation at the back side and front side of PV module representatively. Temperature sensors were installed on the PV module to detect temperature of PV. PIC microcontroller was used to control the DC brushless fan and water pump for switch ON or OFF depend on the temperature of PV module automatically. The performance with and without cooling system are shown in this experiment. The PV module with DC water pump cooling system increase 3.52%, 36.27%, 38.98%in term of output voltage, output current, output power respectively. It decrease 6.36 °C compare than to PV module without DC water pump cooling system. While DC brushless fan cooling system increase 3.47%, 29.55%, 32.23%in term of output voltage, output current, and output power respectively. It decrease 6.1 °C compare than to PV module without DC brushless fan cooling system. The efficiency of PV module with cooling system was increasing compared to PV module without cooling system; this is because the ambient temperature dropped significantly. The higher efficiency of PV cell, the payback period of the system can be shorted and the lifespan of PV module can also be longer. (paper)
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2010-08-05
... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 9-10 Series Airplanes, DC-9-30 Series... existing airworthiness directive (AD), which applies to all McDonnell Douglas Model DC-9-10 series..., 2010). That AD applies to all McDonnell Douglas Corporation Model DC-9-10 series airplanes, DC-9-30...
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A Novel Single Switch Transformerless Quadratic DC/DC Buck-Boost Converter
DEFF Research Database (Denmark)
Mostaan, Ali; A. Gorji, Saman; N. Soltani, Mohsen
2017-01-01
A novel quadratic buck-boost DC/DC converter is presented in this study. The proposed converter utilizes only one active switch and can step-up/down the input voltage, while the existing single switch quadratic buck/boost converters can only work in step-up or step-down mode. First, the proposed ...
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Drilling history core hole DC-8
International Nuclear Information System (INIS)
1978-10-01
Core hole DC-8 was completed in August, 1978 by Boyles Brothers Drilling Company, Spokane, Washington, under subcontract to Fenix and Scission, Inc. The hole was cored for the US Department of Energy and the Rockwell Hanford Operations' Basalt Waste Isolation Program. Fenix and Scisson, Inc. furnished the engineering, daily supervision of the core drilling activities, and geologic core logging for hole DC-8. Core hole DC-8 is located on the Hanford Site near the Wye Barricade and 50 feet northwest of rotary hole DC-7. The Hanford Site vation coordinates for DC-8 are North 14,955.94 feet and West 14,861.92 coordinates for DC-8 are North 14,955.94 feet and West 14,861.92 mean sea level. The purpose of core hole DC-8 was to core drill vertically through the basalt and interbed units for stratigraphic depth determination and core collection, and to provide a borehole for hydrologic testing and cross-hole seismic shear and pressure wave velocity studies with rotary hole DC-7. The total depth of core hole DC-8 was 4100.5 feet. Core recovery exceeded 97 percent of the total footage cored
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Drilling history core hole DC-8
Energy Technology Data Exchange (ETDEWEB)
1978-10-01
Core hole DC-8 was completed in August, 1978 by Boyles Brothers Drilling Company, Spokane, Washington, under subcontract to Fenix and Scission, Inc. The hole was cored for the US Department of Energy and the Rockwell Hanford Operations' Basalt Waste Isolation Program. Fenix and Scisson, Inc. furnished the engineering, daily supervision of the core drilling activities, and geologic core logging for hole DC-8. Core hole DC-8 is located on the Hanford Site near the Wye Barricade and 50 feet northwest of rotary hole DC-7. The Hanford Site vation coordinates for DC-8 are North 14,955.94 feet and West 14,861.92 coordinates for DC-8 are North 14,955.94 feet and West 14,861.92 mean sea level. The purpose of core hole DC-8 was to core drill vertically through the basalt and interbed units for stratigraphic depth determination and core collection, and to provide a borehole for hydrologic testing and cross-hole seismic shear and pressure wave velocity studies with rotary hole DC-7. The total depth of core hole DC-8 was 4100.5 feet. Core recovery exceeded 97 percent of the total footage cored.
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Characterization of diode valve in medium voltage dc/dc converter for wind turbines
DEFF Research Database (Denmark)
Dincan, Catalin Gabriel; Kjær, Philip Carne
2016-01-01
This paper proposes a methodology for characterization of medium voltage (MV), medium frequency (MF) rectifier diode valve. The intended application is for 10MW dc/dc converters used in DC offshore wind turbines. Sensitivity to semiconductor component parameter variation, snubber component tolera...... tolerance, influence of temperature and stray capacitance are analyzed. It is concluded that the largest impact on sensitivity is given by reverse recovery charge variation and differences of temperature between adjacent devices....
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Operation and control of a DC-grid offshore wind farm under DC transmission system faults
DEFF Research Database (Denmark)
Deng, Fujin; Chen, Zhe
2013-01-01
. Consequently, the protection and control strategies of dc systems need to be established. This paper studies a dc-grid offshore wind farm, where the wind power collection system and power transmission system adopt dc technology. In this paper, the redundancy of the HVDC transmission system under faults...... is studied, and a fault ridethrough strategy for the dc-grid offshore wind farm is proposed. The proposed strategy can effectively minimize the impacts of the power transmission system disturbance on the offshore wind farm, and on the ac grid. A dc-grid offshore wind farm example is simulated with PSCAD....../EMTDC, and the results validate the feasibility of the presented redundancy configuration and operation approach, and the fault ridethrough control strategy....
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Open- and Short-Circuit Fault Identification for a Boost dc/dc Converter in PV MPPT Systems
Directory of Open Access Journals (Sweden)
Diego R. Espinoza Trejo
2018-03-01
Full Text Available This paper proposes a fault identification system for short and open-circuit switch faults (SOCSF for a dc/dc converter acting as a Maximum Power Point Tracker (MPPT in Photovoltaic (PV systems. A closed-loop operation is assumed for the boost dc/dc converter. A linearizing control plus a Proportional-Derivative (PD controller is suggested for PV voltage regulation at the maximum power point (MPP. In this study, the SOCSF are modeled by using an additive fault representation and the fault identification (FI system is synthesized departing from a Luenberger observer. Hence, an FI signal is obtained, which is insensitive to irradiance and load current changes, but affected by the SOCSF. For FI purposes, only the sensors used in the control system are needed. Finally, an experimental evaluation is presented by using a solar array simulator dc power supply and a boost dc/dc converter of 175 W in order to validate the ideas this study exposes.
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DEFF Research Database (Denmark)
Yang, Xi-jun; Qu, Hao; Yao, Chen
2014-01-01
As for high power plasma power supply, due to high efficiency and flexibility, multi-channel interleaved multi-stage paralleled Buck DC-DC Converter becomes the first choice. In the paper, two-channel interleaved two- stage paralleled Buck DC-DC Converter powered by three-phase AC power supply...
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Pulsed-DC selfsputtering of copper
International Nuclear Information System (INIS)
Wiatrowski, A; Posadowski, W M; Radzimski, Z J
2008-01-01
At standard magnetron sputtering conditions (argon pressure ∼0.5 Pa) inert gas particles are often entrapped in the formed films. Inert gas contamination can be eliminated by using the self-sustained magnetron sputtering process because it is done in the absence of the inert gas atmosphere. The self-sustained sputtering (SSS) gives also a unique condition during the transport of sputtered particles to the substrate. It is especially useful for filling high aspect ratio submicron scale structures for microelectronics. So far it has been shown that the self-sputtering process can be sustained in the DC operation mode (DC-SSS) only. The main disadvantage of DC-SSS process is instability related to possible arc formation. Usage of pulsed sputtering, similarly to reactive pulsed magnetron sputtering, could eliminate this problem. In this paper results of pulsed-DC self-sustained magnetron sputtering (pulsed DC-SSS) of copper are presented for the first time. The planar magnetron equipped with a 50 mm in diameter and 6 mm thick copper target was powered by DC-power supply modulated by power switch. The maximum target power was about 11 kW (∼550W/cm 2 ). The magnetron operation was investigated as a function of pulsing frequency (20-100 kHz) and duty factor (50-90%). The discharge extinction pressure was determined for these conditions. The plasma emission spectra (400-410nm range) and deposition rates were observed for both DC and pulsed DC sustained self-sputtering processes. The presented results illustrate that stable pulsed DC-SSS process can be obtained at pulsing frequency in the range of 60-100 kHz and duty factor of 70-90%
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Pulsed-DC selfsputtering of copper
Wiatrowski, A.; Posadowski, W. M.; Radzimski, Z. J.
2008-03-01
At standard magnetron sputtering conditions (argon pressure ~0.5 Pa) inert gas particles are often entrapped in the formed films. Inert gas contamination can be eliminated by using the self-sustained magnetron sputtering process because it is done in the absence of the inert gas atmosphere. The self-sustained sputtering (SSS) gives also a unique condition during the transport of sputtered particles to the substrate. It is especially useful for filling high aspect ratio submicron scale structures for microelectronics. So far it has been shown that the self-sputtering process can be sustained in the DC operation mode (DC-SSS) only. The main disadvantage of DC-SSS process is instability related to possible arc formation. Usage of pulsed sputtering, similarly to reactive pulsed magnetron sputtering, could eliminate this problem. In this paper results of pulsed-DC self-sustained magnetron sputtering (pulsed DC-SSS) of copper are presented for the first time. The planar magnetron equipped with a 50 mm in diameter and 6 mm thick copper target was powered by DC-power supply modulated by power switch. The maximum target power was about 11 kW (~550W/cm2). The magnetron operation was investigated as a function of pulsing frequency (20-100 kHz) and duty factor (50-90%). The discharge extinction pressure was determined for these conditions. The plasma emission spectra (400-410nm range) and deposition rates were observed for both DC and pulsed DC sustained self-sputtering processes. The presented results illustrate that stable pulsed DC-SSS process can be obtained at pulsing frequency in the range of 60-100 kHz and duty factor of 70-90%.
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DC injection into low voltage AC networks
Energy Technology Data Exchange (ETDEWEB)
NONE
2005-07-01
This report summarises the results of a study investigating the impact of levels of injected DC current injections on a low voltage AC distribution network systems in order to recommend acceptable limits of DC from microgeneration. Relevant literature is reviewed, and the impact of DC levels in distribution transformers, transformer modelling, and instrumental transformers are discussed. The impact of DC in residual current devices (RCD) and in domestic electricity watt hour meters is examined along with DC enhanced corrosion, corrosion failure, and the measurement of DC current injection. Sources of DC injection outlined include DC from computer power supplies, network faults, geomagnetic phenomena, lighting circuits/dimmers, and embedded generators.
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Transition towards DC micro grids: From an AC to a hybrid AC and DC energy infrastructure
Directory of Open Access Journals (Sweden)
Evi Ploumpidou
2017-12-01
Full Text Available Our electricity is predominantly powered by alternating current (AC, ever since the War of Currents ended in the favor of Nicola Tesla at the end of the 19th century. However, lots of the appliances we use, such as electronics and lights with light-emitting diode (LED technology, work internally on direct current (DC and it is projected that the number of these appliances will increase in the near future. Another contributor to the increase in DC consumption is the ongoing electrification of mobility (Electric Vehicles (EVs. At the same time, photovoltaics (PV generate DC voltages, while the most common storage technologies also use DC. In order to integrate all these appliances and technologies to the existing AC grid, there is a need for converters which introduce power losses. By distributing DC power to DC devices instead of converting it to AC first, it is possible to avoid substantial energy losses that occur every time electricity is converted. This situation initiated the concept for the implementation of the DC-Flexhouse project. A prototype DC installation will be developed and tested in one of the buildings of the developing living lab area called the District of Tomorrow (De Wijk van Morgen which is located in Heerlen, the Netherlands. A neighborhood cooperative (Vrieheide cooperatie is also part of the consortium in order to address the aspect of social acceptance. Although DC seems to be a promising solution for a more sustainable energy system, the business case is still debatable due to both technology- and market-related challenges. The current energy infrastructure is predominantly based on AC, manufacturers produce devices based on AC standards and people are using many AC products across a long life span. This Smart Energy Buildings & Cities (SEB&C PDEng project is a contribution to the DC-Flexhouse project. The aim is to analyze the challenges in the transition to DC micro grids, assess the market potential of DC
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DC-Compensated Current Transformer.
Ripka, Pavel; Draxler, Karel; Styblíková, Renata
2016-01-20
Instrument current transformers (CTs) measure AC currents. The DC component in the measured current can saturate the transformer and cause gross error. We use fluxgate detection and digital feedback compensation of the DC flux to suppress the overall error to 0.15%. This concept can be used not only for high-end CTs with a nanocrystalline core, but it also works for low-cost CTs with FeSi cores. The method described here allows simultaneous measurements of the DC current component.
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Energy Technology Data Exchange (ETDEWEB)
Bjustrom, B
1965-12-01
How stress distribution in dc cables varies with temperature and stress level, influence of polarity reversals and space charges, and different types of overvoltage to which dc cable may be subjected are discussed. Design problems, especially as related to corrosion protection and to mechanical stress caused by wire armoring during manufacturing and laying, accessories and work done on test methods, and the possibility of designing 400 to 600 kV dc cables for transmitting 2000 to 4000 MW are described.
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Comparative evaluation of bidirectional dual active bridge DC-DC converter variants
Sfakianakis, G.; Everts, J.; Huisman, H.; Lomonova, E.A.
2016-01-01
For the realization of DC-DC converters in automotive industry, the Dual Active Bridge (DAB) converter seems to be a promising choice because of its soft-switching and high-power-density capability. Contrary to the traditional 3 level - 3 level (3-3L) DAB, a 3 level - 5 level (3-5L) DAB can operate
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Improvement of burst-mode control of piezoelectric transformer based DC/DC converter
International Nuclear Information System (INIS)
Vasic, Dejan; Liu, Yuan-Ping; Costa, François; Schwander, Denis; Wu, Wen-Jong
2013-01-01
Burst-mode operation is adopted sometimes in piezoelectric transformer based converters for two major purposes: (1) to achieve voltage regulation in DC/DC converters and (2) to achieve dimming control in backlight inverters. Burst-mode control enables the converter to operate at a constant switching frequency as well as to maintain good efficiency at light load conditions. However, in practice, the piezoelectric transformer cannot instantly stop vibrating in the burst-mode due to its high quality factor. The delay in the output voltage change resulting from this behavior influences the accuracy of the regulation. This paper proposes a control strategy to make the piezoelectric transformer stop more quickly so as to enhance the accuracy of burst-mode control. The proposed method only modifies the control signal of the burst-mode driving circuit. The proposed control strategy is verified by experiments in a step-down 9 W DC/DC converter. (paper)
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Stevens-Johnson syndrome in patients on phenytoin and cranial radiotherapy
International Nuclear Information System (INIS)
Khafaga, Y.M.; Jamshed, A.; Allam, A.A.K.; Ezzat, A.; Gray, A.J.; Schultz, H.; Mourad, W.A.; Al Eisa, A.
1999-01-01
The use of phenytoin as a prophylactic anticonvulsant after brain surgery, particularly for brain tumors, is a common practice, regardless of whether the patient has a previous history of convulsions. This treatment policy assumes that the benefits exceed the risks. Four cases are described of adverse reactions of phenytoin during the cocomitant use of cranial radiotherapy. In one patient this proved fatal. There is increasing anecdotal support in the literature for a synergistic effect between phenytoin therapy and cranial radiotherapy that can result in the life-threatening Stevens-Johnson syndrome. While the association is uncommon, four cases within 24 months in one department suggest that the routine use of postoperative phenytoin as a prophylactic anticonvulsant in the absence of a history of seizures may not be warranted, particularly if the patient is to receive cranial radiotherapy. (orig.)
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Modular Power System Configured with Standard Product Hybrid DC-DC Converters, Phase II
National Aeronautics and Space Administration — VPT proposes an innovative concept whereby complex NASA space power electronic systems can be configured using a small number of qualified hybrid DC-DC converter and...
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National Aeronautics and Space Administration — Studying and analyzing the ageing mechanisms of electronic components avionics in systems such as the GPS and INAV are of critical importance. In DC-DC power...
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Simulating and Testing a DC-DC Half-Bridge SLR Converter
2013-06-01
future pulse power demands with ship power, a large bank of capacitors or similar rapid discharge source is required. If capacitors are charged...Single Pulsed Avalanche Energy (j) I" Avalanche Current (i) E,, Repetilive Avalanche Energy (i) dv/dt Peak Diode Recovery dv/dt ® Po Total Power...SLR), battery charging, DC-DC, pulse power, power electronics, SLR converter 15. NUMBER OF PAGES 119 16. PRICE CODE 17. SECURITY CLASSIFICATION
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Efficient Visible Light Communication Transmitters Based on Switching-Mode dc-dc Converters
2018-01-01
Visible light communication (VLC) based on solid-state lighting (SSL) is a promising option either to supplement or to substitute existing radio frequency (RF) wireless communication in indoor environments. VLC systems take advantage of the fast modulation of the visible light that light emitting diodes (LEDs) enable. The switching-mode dc-to-dc converter (SMCdc-dc) must be the cornerstone of the LED driver of VLC transmitters in order to incorporate the communication functionality into LED lighting, keeping high power efficiency. However, the new requirements related to the communication, especially the high bandwidth that the LED driver must achieve, converts the design of the SMCdc-dc into a very challenging task. In this work, three different methods for achieving such a high bandwidth with an SMCdc-dc are presented: increasing the order of the SMCdc-dc output filter, increasing the number of voltage inputs, and increasing the number of phases. These three strategies are combinable and the optimum design depends on the particular VLC application, which determines the requirements of the VLC transmitter. As an example, an experimental VLC transmitter based on a two-phase buck converter with a fourth-order output filter will demonstrate that a bandwidth of several hundred kilohertz (kHz) can be achieved with output power levels close to 10 W and power efficiencies between 85% and 90%. In conclusion, the design strategy presented allows us to incorporate VLC into SSL, achieving high bit rates without damaging the power efficiency of LED lighting. PMID:29642455
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DEFF Research Database (Denmark)
Liu, Changjin; Xu, Dehong; Zhu, Nan
2013-01-01
Unbalanced grid voltage causes a large second-order harmonic current in the dc-link capacitors as well as dc-voltage fluctuation, which potentially will degrade the lifespan and reliability of the capacitors in voltage source converters. This paper proposes a novel dc-capacitor current control...... method for a grid-side converter (GSC) to eliminate the negative impact of unbalanced grid voltage on the dc-capacitors. In this method, a dc-capacitor current control loop, where a negative-sequence resonant controller is used to increase the loop gain, is added to the conventional GSC current control...... loop. The rejection capability to the unbalanced grid voltage and the stability of the proposed control system are discussed. The second-order harmonic current in the dc capacitor as well as dc-voltage fluctuation is very well eliminated. Hence, the dc capacitors will be more reliable under unbalanced...
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Review of The Joy of x: A Guided Tour of Math, from One to Infinity by Steven Strogatz
Directory of Open Access Journals (Sweden)
Michael T. Catalano
2014-07-01
Full Text Available Strogatz, Steven. The Joy of x: A Guided Tour of Math, from One to Infinity, (New York, NY, Houghton Mifflin Harcourt, 2012. 316 pp. ISBN 978-0-547-51765-0 The Joy of x: A Guided Tour of Math, from One to Infinity, by Steven Strogatz, is an engaging and example-filled argument for mathematics as a valuable and enjoyable activity. The thirty chapters are divided into six parts, entitled Numbers, Relationships, Shapes, Change, Data, and Frontiers. The discussion ranges from intuitive explanations of basic concepts such as place value, the four arithmetic operations, percentage increase and decrease, and solving equations, to “higher” levels of mathematics such as calculus, probability and statistics, group theory, and the nature of infinity. As in John Allen Paulos’ work, Beyond Numeracy, the chapters are short and punchy, and they can be read independently. While the book is not specifically devoted to numeracy, several chapters, especially those in Part Five on Data, address ideas and examples relevant to quantitative literacy.
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Directory of Open Access Journals (Sweden)
Rui Li
2016-12-01
Full Text Available The AC voltage control of a DC/DC converter based on the modular multilevel converter (MMC is considered under normal operation and during a local DC fault. By actively setting the AC voltage according to the two DC voltages of the DC/DC converter, the modulation index can be near unity, and the DC voltage is effectively utilized to output higher AC voltage. This significantly decreases submodule (SM capacitance and conduction losses of the DC/DC converter, yielding reduced capital cost, volume, and higher efficiency. Additionally, the AC voltage is limited in the controllable range of both the MMCs in the DC/DC converter; thus, over-modulation and uncontrolled currents are actively avoided. The AC voltage control of the DC/DC converter during local DC faults, i.e., standby operation, is also proposed, where only the MMC connected on the faulty cable is blocked, while the other MMC remains operational with zero AC voltage output. Thus, the capacitor voltages can be regulated at the rated value and the decrease of the SM capacitor voltages after the blocking of the DC/DC converter is avoided. Moreover, the fault can still be isolated as quickly as the conventional approach, where both MMCs are blocked and the DC/DC converter is not exposed to the risk of overcurrent. The proposed AC voltage control strategy is assessed in a three-terminal high-voltage direct current (HVDC system incorporating a DC/DC converter, and the simulation results confirm its feasibility.
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Feld, Lutz Werner; Karpinski, Waclaw; Klein, Katja; Lipinski, Martin; Pauls, Alexander Josef; Preuten, Marius; Rauch, Max Philip; Wangelik, Frederik; Wlochal, Michael
2017-01-01
The 2S silicon strip modules for the CMS Phase-2 tracker upgrade will require two operating voltages. These will be provided via a two-step DC-DC conversion powering scheme, in which one DC-DC converter delivers 2.5\\,V while the second DC-DC converter receives 2.5\\,V at its input and converts it to 1.2\\,V. The DC-DC converters will be mounted on a flex PCB, the service hybrid, together with an opto-electrical converter module (VTRx+) and a serializer (LP-GBT). The service hybrid will be mounted directly on the 2S module. A prototype service hybrid has been developed and its performance has been evaluated, including radiative and conductive noise emissions, and efficiency. In addition system tests with a prototype module have been performed. In this report the service hybrid will be described and the test results will be summarized.
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A suitable model plant for control of the set fuel cell-DC/DC converter
Energy Technology Data Exchange (ETDEWEB)
Andujar, J.M.; Segura, F.; Vasallo, M.J. [Departamento de Ingenieria Electronica, Sistemas Informaticos y Automatica, E.P.S. La Rabida, Universidad de Huelva, Ctra. Huelva - Palos de la Frontera, S/N, 21819 La Rabida - Palos de la Frontera Huelva (Spain)
2008-04-15
In this work a state and transfer function model of the set made up of a proton exchange membrane (PEM) fuel cell and a DC/DC converter is developed. The set is modelled as a plant controlled by the converter duty cycle. In addition to allow setting the plant operating point at any point of its characteristic curve (two interesting points are maximum efficiency and maximum power points), this approach also allows the connection of the fuel cell to other energy generation and storage devices, given that, as they all usually share a single DC bus, a thorough control of the interconnected devices is required. First, the state and transfer function models of the fuel cell and the converter are obtained. Then, both models are related in order to achieve the fuel cell+DC/DC converter set (plant) model. The results of the theoretical developments are validated by simulation on a real fuel cell model. (author)
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Research of digital controlled DC/DC converter based on STC12C5410AD
Chen, Dan-Jiang; Jin, Xin; Xiao, Zhi-Hong
2010-02-01
In order to study application of digital control technology on DC/DC converter, principle of increment mode PID control algorithm was analyzed in the paper. Then, a SCM named STC12C5410AD was introduced with its internal resources and characteristics. The PID control algorithm can be implemented easily based on it. The output of PID control was used to change the value of a variable that is 255 times than duty cycle, and this reduced the error of calculation. The valid of the presented algorithm was verified by an experiment for a BUCK DC/DC converter. The experimental results indicated that output voltage of the BUCK converter is stable with low ripple.
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Directory of Open Access Journals (Sweden)
Noroozian
2009-06-01
Full Text Available This paper presents the modeling and simulation of a proton exchange membrane fuel cell (PEMFC generation system for off-grid and on-grid operation and configuration. A fuel cell DG system consists of a fuel cell power plant, a DC/DC converter and a DC/AC inverter. The dynamic model for fuel cell array and its power electronic interfacing are presented also a multi-input single output (MISO DC/DC converter and its control scheme is proposed and analyzed. This DC/DC converter is capable of interfacing fuel cell arrays to the DC/AC inverter. Also the mathematical model of the inverter is obtained by using average technique. Then the novel control strategy of DC/AC inverter for different operating conditions is demonstrated. The simulation results show the effectiveness of the suggested control systems under both on-grid and off-grid operation modes.
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RF-superimposed DC and pulsed DC sputtering for deposition of transparent conductive oxides
International Nuclear Information System (INIS)
Stowell, Michael; Mueller, Joachim; Ruske, Manfred; Lutz, Mark; Linz, Thomas
2007-01-01
Transparent conductive oxide films are widely used materials for electronic applications such as flat panel displays and solar cells. The superposition of DC and pulsed DC power by a certain fraction of RF power was applied to deposit indium tin oxide films. This technique allows an additional tuning of different parameters relevant to film growth, and yields high quality films even under kinetically limited conditions. A long-term stable RF/DC process could be realized by using different combinations of standard power supply components, which includes a fully reliable arc handling system for both the RF and DC generators. The effectiveness of the arc handling system is illustrated by the current and voltage behavior recorded for actual arcing events. The resistivity of indium tin oxide films is strongly influenced by the respective sputtering mode. The best resistivity values of 145-148 μΩ cm were obtained by RF-superimposed pulsed DC sputtering at a pulse frequency between 100 and 200 kHz and a substrate temperature as low as 140 deg. C. In addition, the films were extremely smooth with a surface roughness of 1-2.5 nm
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The application of standardized control and interface circuits to three dc to dc power converters.
Yu, Y.; Biess, J. J.; Schoenfeld, A. D.; Lalli, V. R.
1973-01-01
Standardized control and interface circuits were applied to the three most commonly used dc to dc converters: the buck-boost converter, the series-switching buck regulator, and the pulse-modulated parallel inverter. The two-loop ASDTIC regulation control concept was implemented by using a common analog control signal processor and a novel digital control signal processor. This resulted in control circuit standardization and superior static and dynamic performance of the three dc-to-dc converters. Power components stress control, through active peak current limiting and recovery of switching losses, was applied to enhance reliability and converter efficiency.
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Design of the DC-DC power stage of the capacitor charger for MAXIDISCAP power converters
Cravero, Jean-Marc
2013-01-01
This technical report presents the design of the DC-DC power stage of the capacitor charger for MAXIDISCAP power converters. The power stage is based on a half bridge series resonant converter in Discontinuous Conduction Mode (DCM). This simple and robust topology allows obtaining a current source behavior with a low switching losses power stage. The associated control stage is implemented using a commercial controller which has differenti nternal circuits that allows a high integration of the converter control system. The report presents the design and tuning criteria for the DC-DC converter, including the power stage and the control system.
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Analysis of DC/DC Converter Efficiency for Energy Storage System Based on Bidirectional Fuel Cells
DEFF Research Database (Denmark)
Pittini, Riccardo; Zhang, Zhe; Andersen, Michael A. E.
2013-01-01
interface to the grid. In power electronics, the converter efficiency is characterized at fixed operating voltage for various output power. This type of characterization is not suitable for fuel cells, since as the power from the fuel cell increases, the cell voltage decreases. This paper analyses how......Renewable energy sources are fluctuating depending on the availability of the energy source. For this reason, energy storage is becoming more important and bidirectional fuel cells represent an attractive technology. Fuel cells require highcurrent low-voltage dc-dc or dc-ac converters as power...... the fuel cell I-V characteristics influences the power electronics converter efficiency and their consequence on the overall system. A loaddependent efficiency curve is presented based on experimental results from a 6 kW dc-dc converter prototype including the most suitable control strategy which maximizes...
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Design and Implementation of Digital Current Mode Controller for DC-DC Converters
DEFF Research Database (Denmark)
Taeed, Fazel
to be regulated by a closed-loop controller. The Peak Current Mode Control (PCMC) is one of the most promising control methods for dc-dc converters. It has been known for high bandwidth (speed), and inherent current protection. Increasing the controller bandwidth decreases the output filter size and cost. Analog...
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Soft switching bidirectional DC-DC converter for ultracapacitor-batteries interface
International Nuclear Information System (INIS)
Adib, Ehsan; Farzanehfard, Hosein
2009-01-01
In this paper a new soft switching bidirectional DC-DC converter is introduced which can be applied as the interface circuit between ultracapacitors and batteries or fuel cells. All semiconductor devices in the proposed converter are soft switched while the control circuit remains PWM. Due to achieved soft switching condition, the energy conversion through the proposed converter is highly efficient. The proposed converter is analyzed and a prototype converter is implemented. The presented experimental results confirm the theoretical analysis.
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Design and modelling of high gain DC-DC converters for fuel cell hybrid electric vehicles
Elangovan, D.; Karthigeyan, V.; Subhanu, B.; Ashwin, M.; Arunkumar, G.
2017-11-01
Transportation (Diesel and petrol internal combustion engine vehicles) approximately contributes to 25.5% of total CO2 emission. Thus diesel and petrol engine vehicles are the most dominant contributors of CO2 emission which leads global warming which causes climate change. The problem of CO2 emission and global warming can be reduced by focusing on renewable energy vehicles. Out of the available renewable energy sources fuel cell is the only source which has reasonable efficiency and can be used in vehicles. But the main disadvantage of fuel cell is its slow response time. So energy storage systems like batteries and super capacitors are used in parallel with the fuel cell. Fuel cell is used during steady state vehicle operation while during transient conditions like starting, acceleration and braking batteries and super capacitors can supply or absorb energy. In this paper a unidirectional fuel cell DC-DC converter and bidirectional energy storage system DC-DC converter is proposed, which can interface dc sources at different voltage levels to the dc bus and also it can independently control the power flow from each energy source to the dc bus and vice versa. The proposed converters are designed and simulated using PSIM version 9.1.1 and gate pulse pattern, input and output voltage waveforms of the converters for steady state operation are studied.
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Modelling and Control Design of a Dual Buck-Boost AC/DC Converter Used in the DC Nano-Grid
DEFF Research Database (Denmark)
Wu, Weimin; Liu, Yuan; Wang, Houqing
2016-01-01
Due to widely used DC characterized loads and more distributed power generation sources, the DC Nano-grid becomes more and more popular and seen as an alternative to the AC-grid in future. For the safety considerations, the DC Nano-grid should provide reliable grounding for the residential loads...... like the low voltage AC power system. In this paper, a dual Buck-Boost AC/DC converter for use in the united grounding configuration based DC Nano-grid with three terminal outputs is proposed. It will be much easy to construct an efficient DC Nano-grid based on the existing low AC power system by using...
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Magnetically integrated high step-up resonant DC-DC converter for distributed photovoltaic systems
DEFF Research Database (Denmark)
Vinnikov, Dmitri; Chub, Andrii; Liivik, Elizaveta
2017-01-01
In this paper magnetically integrated resonant single-switch quasi-Z-source DC-DC converter is evaluated as a candidate topology for the low-cost photovoltaic microconverter. The derivation of the topology and its basic operation principle are explained. Generalized design guidelines...
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Drilling history core hole DC-4
International Nuclear Information System (INIS)
1978-12-01
Core hole DC-4 was completed at a depth of 3998 feet in December, 1978 by Boyles Brothers Drilling Company, Spokane, Washington, under subcontract to Fenix and Scission, Inc. The hole was cored for the US Department of Energy and the Rockwell Hanford Operations' Basalt Waste Isolation Program. Fenix and Sicsson, Inc. furnished the engineering, daily supervision of the cable tool and core drilling activities, and geological core logging for DC-4. Core hole DC-4 is located on the Hanford Site about 3 miles east of the Yakima Barricade and approximately 103 feet southwest of rotary hole DC-5, which was completed to 3990 feet in February, 1978. Hanford Site coordinates reported for hole DC-4 are north 49,385.62 feet and west 85,207.63 feet, and Washington State coordinates are north 454,468.73 feet and east 2,209,990.87 feet. No elevation survey is available for hole DC-4, but it is approximately 745 feet above mean sea level based upon the survey of hole DC-5, which has a reported elevation of 745.16 feet on the top of the 3-inch flange. The purpose of core hole DC-4 was to core drill vertically through the basalt and interbed units for stratigraphic depth determination and core collection, and to provide a borehole for hydrologic testing, cross-hole seismic shear, and pressure wave velocity studies with rotary hole DC-5. Hole DC-4 was drilled through the overburden into basalt bedrock by cable tool methods (0-623 feet) and continuously cored through the final interval (623 to 3998 feet).Core recovery was 95.8 percent of the total footage cored
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DC-DC Type High-Frequency Link DC for Improved Power Quality of Cascaded Multilevel Inverter
Sadikin, Muhammad; Senjyu, Tomonobu; Yona, Atsushi
2013-06-01
Multilevel inverters are emerging as a new breed of power converter options for power system applications. Recent advances in power switching devices enabled the suitability of multilevel inverters for high voltage and high power applications because they are connecting several devices in series without the need of component matching. Usually, a transformerless battery energy storage system, based on a cascaded multilevel inverter, is used as a measure for voltage and frequency deviations. System can be reduced in size, weight, and cost of energy storage system. High-frequency link circuit topology is advantageous in realizing compact and light-weight power converters for uninterruptible power supply systems, new energy systems using photovoltaic-cells, fuel-cells and so on. This paper presents a DC-DC type high-frequency link DC (HFLDC) cascaded multilevel inverter. Each converter cell is implemented a control strategy for two H-bridge inverters that are controlled with the same multicarrier pulse width modulation (PWM) technique. The proposed cascaded multilevel inverter generates lower voltage total harmonic distortion (THD) in comparison with conventional cascaded multilevel inverter. Digital simulations are carried out using PSCAD/EMTDC to validate the performance of the proposed cascaded multilevel inverter.
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Wide Temperature Range DC-DC Boost Converters for Command/Control/Drive Electronics, Phase I
National Aeronautics and Space Administration — We shall develop wide temperature range DC-DC boost converters that can be fabricated using commercial CMOS foundries. The boost converters will increase the low...
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DEFF Research Database (Denmark)
Dragicevic, Tomislav; Lu, Xiaonan; Quintero, Juan Carlos Vasquez
2016-01-01
distribution applications such as traction, telecom, vehicular and distributed power systems can be classified under DC MG framework and ongoing development and expansion of the field is largely influenced by concepts used over there. This paper aims firstly to shed light on the practical design aspects of DC...... MG technology concerning typical power hardware topologies and their suitability for different emerging smart grid applications. Then, an overview of the state of the art in DC MG protection and grounding is provided. Owing to the fact that there is no zero current crossing, an arc that appears upon...
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Selection of DC/DC converter for offshore wind farms with MVDC power collection
DEFF Research Database (Denmark)
Dincan, Catalin Gabriel; Kjær, Philip Carne; Chen, Yu-Hsing
2017-01-01
Four DC/DC converters are analyzed and compared with respects to availability, efficiency, ratings, repair costs and power density. Intended application is offshore wind farms with MVDC power collection. The selected topology is a new series resonant converter, which offers 99% efficiency across...
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Integrated Three-Port DC-DC Converter for Photovoltaic (PV) Battery Stand-alone Systems
DEFF Research Database (Denmark)
Ouyang, Ziwei; Andersen, Michael A. E.
2016-01-01
of solar energy. Moreover, a novel transformer configuration enables variable turns ratio controlled by the phase between the two current excitations subjected to the primary windings, allowing a wider input/output range. 1 kW experimental prototype has been built to demonstrate a wellmanaged power flow......Several power sources such as PV solar arrays and battery are often used to manage the power flow for a photovoltaic (PV) based stand-alone power system due to the fluctuation nature of solar energy resource, and deliver a continuous power to the users in an appropriate form. Traditionally, three...... different single-input single-output (SISO) dc/dc converters would have been used. To reduce the cost and improve the power density of the system, an integrated three-port isolated dc/dc converter is proposed in this paper. It can realize all functions of the energy delivery due to the fluctuation nature...
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Huang, Peter Jen-Hung
This research first proposes a method to merge photovoltaic (PV) cells or PV panels within the internal components DC-DC converters. The purpose of this merged structure is to reconfigure the PV modules between series and parallel connections using high switching frequencies (hundreds of kHz). This leads to multi-levels of voltages and currents that become applied to the output filter of the converter. Further, this research introduces a concept of a switching cell that utilizes the reconfiguration of series and parallel connections in DC-DC converters. The switching occurs at high switching frequency and the switches can be integrated to be within the solar panels or in between the solar cells. The concept is generalized and applied to basic buck and boost topologies. As examples of the new types of converters: reconfigurable PV-buck and PV-boost converter topologies are presented. It is also possible to create other reconfigurable power converters: non-isolated and isolated topologies. Analysis, simulation and experimental verification for the reconfigurable PV-buck and PV-boost converters are presented extensively to illustrate proof of concept. Benefits and drawbacks of the new approach are discussed. The second part of this research proposes to utilize the internal solar cell capacitance and internal solar module wire parasitic inductances to replace the input capacitor and filter inductor in boost derived DC-DC converters for energy harvesting applications. High switching frequency (MHz) hard switched and resonant boost converters are proposed. Their analysis, simulation and experimental prototypes are presented. A specific proof-of-concept application is especially tested for foldable PV panels, which are known for their high internal wire inductance. The experimental converters successfully boost solar module voltage without adding any external input capacitance or filter inductor. Benefits and drawbacks of new proposed PV submodule integrated boost
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Soft switching bidirectional DC-DC converter for ultracapacitor-batteries interface
Energy Technology Data Exchange (ETDEWEB)
Adib, Ehsan; Farzanehfard, Hosein [Dept. of Electrical and Computer Engineering, Isfahan Univ. of Technology (Iran)
2009-12-15
In this paper a new soft switching bidirectional DC-DC converter is introduced which can be applied as the interface circuit between ultracapacitors and batteries or fuel cells. All semiconductor devices in the proposed converter are soft switched while the control circuit remains PWM. Due to achieved soft switching condition, the energy conversion through the proposed converter is highly efficient. The proposed converter is analyzed and a prototype converter is implemented. The presented experimental results confirm the theoretical analysis. (author)
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International Nuclear Information System (INIS)
Hagihara, Yasushi; Ueno, Masato; Mizushima, Yasuaki; Matsuoka, Tetsuya
2011-01-01
Recently, decompressive craniectomy (DC) for refractory intracranial hypertension (IH) has been widely reevaluated, and many researchers support the advantages of early and aggressive DC in the management of severe head trauma. We too applied DC in the early stages of IH, and confirmed its favorable results compared to those of the standard treatment. In patients with evacuate masses (EM), DC was determined based on the intraoperative condition of the brain parenchyma; in those without EM, intracranial pressure (ICP) ≥30 mmHg was considered the criterion for DC. However, in some cases, the expected brain edema (BE) was absent after DC, and DC seemed unnecessary on retrospection. Here, the effectiveness of DC performed at our hospital and its predictive factors were investigated. Of the 26 DCs performed in the past 3.5 years, 9 were ineffective because the expected BEs were absent on postoperative computed tomography. In those 9 cases, the Glasgow coma scale (GCS) scores and D-dimer of fibrinogen degradation product (FDP-DD) were significantly higher and lower, respectively, than those of the control group. Patients with EM showed similar trends regarding the GCS score and FDP-DD, both of which are probable indicators of BE. In patients without EM, the GCS score and FDP-DD were normal, but their base excess at admission was significantly low with increased ICP, requiring DC. GCS score and FDP-DD may represent the extent of mechanically damaged brain, and this may explain their relation with DC effectiveness in patients with EM. In patients without EM and with mild brain damage, base excess that reflects the respiratory or circulatory disorder should be the predictor for BE. (author)
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Exploration of Charge Recycling DC-DC Conversion Using a Switched Capacitor Regulator
Directory of Open Access Journals (Sweden)
Mircea R. Stan
2013-07-01
Full Text Available The increasing popularity of DVFS (dynamic voltage frequency scaling schemes for portable low power applications demands highly efficient on-chip DC-DC converters. The primary aim of this work is to enable increased efficiency of on-chip DC-DC conversion for near-threshold operation of multicore chips. The idea is to supply nominal (high off-chip voltage to the cores which are then “voltage-stacked” to generate the near-threshold (low voltages based on Kirchhoff’s voltage law through charge recycling. However, the effectiveness of this implicit down-conversion is affected by the current imbalance among the cores. The paper presents a design methodology and optimization strategy for highly efficient charge recycling on-chip regulation using a push-pull switched capacitor (SC circuit. A dual-boundary hysteretic feedback control circuit has been designed for stacked loads. A stacked-voltage domain with its self-regulation capability combined with a SC converter has shown average efficiency of 78%–93% for 2:1 down-conversion with ILoad (max of 200 mA and workload imbalance varying from 0–100%.
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Hierarchical Control for Multiple DC-Microgrids Clusters
DEFF Research Database (Denmark)
Shafiee, Qobad; Dragicevic, Tomislav; Vasquez, Juan Carlos
2014-01-01
DC microgrids (MGs) have gained research interest during the recent years because of many potential advantages as compared to the ac system. To ensure reliable operation of a low-voltage dc MG as well as its intelligent operation with the other DC MGs, a hierarchical control is proposed in this p......DC microgrids (MGs) have gained research interest during the recent years because of many potential advantages as compared to the ac system. To ensure reliable operation of a low-voltage dc MG as well as its intelligent operation with the other DC MGs, a hierarchical control is proposed...
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DEFF Research Database (Denmark)
Forouzesh, Mojtaba; Shen, Yanfeng; Siwakoti, Yam Prasad
2018-01-01
with a common ground connection of the input and output make the proposed topology a proper candidate for a transformer-less grid connected photovoltaic systems. The operating performance, analysis and mathematical derivations of the proposed dc-dc converter have been demonstrated in the paper. Moreover......This paper introduces a non-isolated high step-up dc-dc converter with dual coupled inductors suitable for distributed generation applications. By implementing an input parallel connection, the proposed dc-dc structure inherits shared input current with low ripple, which also requires small...... capacitive filter at its input. Moreover, this topology can reach high voltage gain by using dual coupled inductors in series connection at the output stage. The proposed converter uses active clamp circuits with a shared clamp capacitor for the main switches. In addition to the active clamp circuit...
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Directory of Open Access Journals (Sweden)
Muh. Zakiyullah Romdlony
2012-07-01
Full Text Available Well-regulated DC bus voltage is the important point to guarantee the power demand in hybrid vehicle applications. Voltage regulation can be achieved with control method that build switching signal on DC-DC converter. This paper describes design and small scale experimental results of bus voltage regulation control of the DC-DC bidirectional converter with battery and supercapacitor as energy source. The control system consists of two control loops, the outer loop that get DC bus voltage feedback using PI anti-windup back calculation control method. This outer loop will generate a reference current for the inner loop that implement hysteresis control. The inner control loop will compare that reference curent with the source current obtained from the current sensor. Simulation and experimental results show that bus voltage is well-regulated under the load changes with 1% voltage ripple.
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Light-weight DC to very high voltage DC converter
Energy Technology Data Exchange (ETDEWEB)
Druce, Robert L. (Union City, CA); Kirbie, Hugh C. (Dublin, CA); Newton, Mark A. (Livermore, CA)
1998-01-01
A DC-DC converter capable of generating outputs of 100 KV without a transformer comprises a silicon opening switch (SOS) diode connected to allow a charging current from a capacitor to flow into an inductor. When a specified amount of charge has flowed through the SOS diode, it opens up abruptly; and the consequential collapsing field of the inductor causes a voltage and current reversal that is steered into a load capacitor by an output diode. A switch across the series combination of the capacitor, inductor, and SOS diode closes to periodically reset the SOS diode by inducing a forward-biased current.
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Current Mode Control for LLC Series Resonant DC-to-DC Converters
Jinhaeng Jang; Syam Kumar Pidaparthy; Byungcho Choi
2015-01-01
Conventional voltage mode control only offers limited performance for LLC series resonant DC-to-DC converters experiencing wide variations in operational conditions. When the existing voltage mode control is employed, the closed-loop performance of the converter is directly affected by unavoidable changes in power stage dynamics. Thus, a specific control design optimized at one particular operating point could become unacceptable when the operational condition is varied. This paper presents a...
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Floating high step-down stacked dc-dc converter based on buck-boost cells
Tibola, G.; Duarte, J.L.; Blinov, A.
2015-01-01
In some high power dc-dc applications, where high voltage is present, a converter with high step-down ratio is required in order to provide an isolated low power auxiliary supply. This requirement represents a challenge and many topologies are currently being researched. The analysis of a
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Directory of Open Access Journals (Sweden)
I Wayan Arta Wijaya
2009-05-01
Full Text Available Pengubah daya DC-DC topologi boost dapat menghasilkan tegangan yang lebih tinggi dari tegangan input dengan riak (ripple yang kecil dan efisiensi yang cukup tinggi. Nilai dari sebuah induktansi dan kapasitansi dari pengubah daya DC-DC dengan menggunakan topologi boost dioptimalkan menggunakan analisa transien. Fungsi ini diatur berdasarkan pada analisa dari pengubah daya selama kondisi transien. Nilai induktansi dan kapasitansi yang telah dioptimalkan dengan perhitungan dibandingkan dalam simulasi pada pengubah daya DC-DC dan hasilnya akan dibuktikan dengan menggunakan hasil percobaan. Nilai optimal untuk kapasitor dan induktor pada frekuensi 666,7 Hz, siklus kerja (duty cycle 66,7 %, resistansi output 36 Πdan tegangan input 12 volt adalah 1038 μF dan 11,9 mH
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Rhesus macaque and chimpanzee DC-SIGN act as HIV/SIV gp120 trans-receptors, similar to human DC-SIGN
Geijtenbeek, T. B.; Koopman, G.; van Duijnhoven, G. C.; van Vliet, S. J.; van Schijndel, A. C.; Engering, A.; Heeney, J. L.; van Kooyk, Y.
2001-01-01
Dendritic cells (DC) have been implicated in the pathogenesis of both human and simian immunodeficiency viruses (HIV and SIV, respectively). The DC-specific HIV-1 trans-receptor DC-SIGN is thought to be essential for viral dissemination by DC. Abundant expression in lymphoid tissues also implies a
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Directory of Open Access Journals (Sweden)
Zheng Wang
2016-01-01
Full Text Available Three-port isolated (TPI bidirectional DC/DC converters have three energy ports and offer advantages of large voltage gain, galvanic isolation ability and high power density. For this reason this kind of converters are suitable to connect different energy sources and loads in electric and hybrid vehicles. The purpose of this paper is to propose chaotic modulation and the related control scheme for TPI bidirectional DC/DC converters, in such a way that the switching harmonic peaks can be suppressed in spectrum and the conducted electromagnetic interference (EMI is reduced. Two chaotic modulation strategies, namely the continuously chaotic modulation and the discretely chaotic modulation are presented. These two chaotic modulation strategies are applied for TPI bidirectional DC/DC converters with shifted-phase angle based control and phase-shifted PWM control. Both simulation and experiments are given to verify the validity of the proposed chaotic modulation-based control schemes.
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Costa, Carla
2015-01-01
This paper reviews the history of the emergence of the molds and plastics industries in Portugal, finding that this history fits nicely with the accounts—originally proposed in Steven Klepper’s various works—of new industries emerging from older, related industries, and regional clusters emerging
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Directory of Open Access Journals (Sweden)
M. Khalilzadeh
2016-12-01
Full Text Available In this paper, a stochastic approach is proposed for reliability assessment of bidirectional DC-DC converters, including the fault-tolerant ones. This type of converters can be used in a smart DC grid, feeding DC loads such as home appliances and plug-in hybrid electric vehicles (PHEVs. The reliability of bidirectional DC-DC converters is of such an importance, due to the key role of the expected increasingly utilization of DC grids in modern Smart Grid. Markov processes are suggested for reliability modeling and consequently calculating the expected effective lifetime of bidirectional converters. A three-leg bidirectional interleaved converter using data of Toyota Prius 2012 hybrid electric vehicle is used as a case study. Besides, the influence of environment and ambient temperature on converter lifetime is studied. The impact of modeling the reliability of the converter and adding reliability constraints on the technical design procedure of the converter is also investigated. In order to investigate the effect of leg increase on the lifetime of the converter, single leg to five-leg interleave DC-DC converters are studied considering economical aspect and the results are extrapolated for six and seven-leg converters. The proposed method could be generalized so that the number of legs and input and output capacitors could be an arbitrary number.
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DEFF Research Database (Denmark)
Padmanaban, Sanjeevi Kumar; Blaabjerg, Frede; Siano, Pierluigi
2016-01-01
This paper presents the control strategies by Proportional-Integral (P-I) and Fuzzy Logic (FL) for a DC-DC boost power converter for high output voltage configuration. Standard DC-DC converters are traditionally used for high voltage direct current (HVDC) power transmission systems. But, lack its...... converter with inbuilt voltage-lift technique and overcome the aforementioned deficiencies. Further, the control strategy is adapted based on proportional-integral (P-I) and fuzzy logic, closed-loop controller to regulate the outputs and ensure the performances. Complete hardware prototype of EHV converter...... performances in terms of efficiency, reduced transfer gain and increased cost with sensor units. Moreover, the internal self-parasitic components reduce the output voltage and efficiency of classical high voltage converters (HVC). This investigation focused on extra high-voltage (EHV) DC-DC boost power...
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A Novel Quasi-SEPIC High-Voltage Boost DC-DC Converter
DEFF Research Database (Denmark)
Siwakoti, Yam Prasad; N. Soltani, Mohsen; Blaabjerg, Frede
2017-01-01
This paper proposes a modified coupled-inductor SEPIC dc-dc converter for low power and high voltage gain applications such as for piezoelectric drive systems. The converter uses the same components as of SEPIC converter with an additional diode. Compared to conventional topologies with similar...... voltage gain expression, the proposed topology uses less components to achieve same or even higher voltage gain. This helps to design a very compact and light weight converter with higher power density at lower cost. Due to brevity, the principle of operation, theoretical analysis and comparison supported...
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Properties of DLC coatings deposited by dc and dc with superimposed pulsed vacuum arc
International Nuclear Information System (INIS)
Zavaleyev, V.; Walkowicz, J.; Aksyonov, D.S.; Luchaninov, A.A.; Reshetnyak, E.N.; Strel'nitskij, V.E.
2014-01-01
Comparative studies of the structure, mechanical and tribological properties of DLC coatings deposited in DC and DC with superimposed high current pulse modes of operation vacuum-arc plasma source with the graphite cathode are presented. Imposition the pulses of high current on DC vacuum-arc discharge allows both increase the deposition rate of DLC coating and reduce the residual compressive stress in the coatings what promotes substantial improvement the adhesion to the substrate. Effect of vacuum arc plasma filtration with Venetian blind filter on the deposition rate and tribological characteristics of the coatings analyzed.
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Osteo-odonto keratoprosthesis in Stevens-Johnson syndrome: a case report.
Sc, Reddy; I, Tajunisah; T, Tan D
2011-01-01
To report a successful osteo-odonto keratoprosthesis (OOKP) procedure in a case of end stage of corneal blindness due to Stevens-Johnson syndrome (SJS). An interventional case report. We describe a 35-year-old Indian woman, a known case of SJS with bilateral dry eyes and corneal blindness (failed corneal graft with vascularised total corneal opacity in the right eye and non-healing corneal ulcer in the left eye). Vision was hand movement only in both eyes. The corneal ulcer healed with medical treatment resulting in vascularised total corneal opacity with no improvement in vision. OOKP was performed in the right eye and the vision was improved from hand movement to 6/6. The same vision was maintained in the right eye at the last follow-up 5 years after surgery. OOKP provides good visual rehabilitation with long-term anatomically stable prosthesis in patients with end-stage of ocular surface disorders and corneal blindness secondary to SJS.
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Light-weight DC to very high voltage DC converter
Druce, R.L.; Kirbie, H.C.; Newton, M.A.
1998-06-30
A DC-DC converter capable of generating outputs of 100 KV without a transformer comprises a silicon opening switch (SOS) diode connected to allow a charging current from a capacitor to flow into an inductor. When a specified amount of charge has flowed through the SOS diode, it opens up abruptly; and the consequential collapsing field of the inductor causes a voltage and current reversal that is steered into a load capacitor by an output diode. A switch across the series combination of the capacitor, inductor, and SOS diode closes to periodically reset the SOS diode by inducing a forward-biased current. 1 fig.
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The 25 kW resonant dc/dc power converter
Robson, R. R.
1983-01-01
The feasibility of processing 25-kW of power with a single, transistorized, series resonant converter stage was demonstrated by the successful design, development, fabrication, and testing of such a device which employs four Westinghouse D7ST transistors in a full-bridge configuration and operates from a 250-to-350 Vdc input bus. The unit has an overall worst-case efficiency of 93.5% at its full rated output of 1000 V and 25 A dc. A solid-state dc input circuit breaker and output-transient-current limiters are included in and integrated into the design. Full circuit details of the converter are presented along with the test data.
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Elangovan, D.; Archana, R.; Jayadeep, V. J.; Nithin, M.; Arunkumar, G.
2017-11-01
More than fifty percent Indian population do not have access to electricity in daily lives. The distance between the power generating stations and the distribution centers forms one of the main reasons for lack of electrification in rural and remote areas. Here lies the importance of decentralization of power generation through renewable energy resources. In the present world, electricity is predominantly powered by alternating current, but most day to day devices like LED lamps, computers and electrical vehicles, all run on DC power. By directly supplying DC to these loads, the number of power conversion stages was reduced, and overall system efficiency increases. Replacing existing AC network with DC is a humongous task, but with power electronic techniques, this project intends to implement DC grid at a household level in remote and rural areas. Proposed work was designed and simulated successfully for various loads amounting to 250 W through appropriate power electronic convertors. Maximum utilization of the renewable sources for domestic and commercial application was achieved with the proposed DC topology.
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Static and Dynamic Characteristics of DC-DC Converter Using a Digital Filter
Kurokawa, Fujio; Okamatsu, Masashi
This paper presents the regulation and dynamic characteristics of the dc-dc converter with digital PID control, the minimum phase FIR filter or the IIR filter, and then the design criterion to improve the dynamic characteristics is discussed. As a result, it is clarified that the DC-DC converter using the IIR filter method has superior performance characteristics. The regulation range is within 1.3%, the undershoot against the step change of the load is less than 2% and the transient time is less than 0.4ms with the IIR filter method. In this case, the switching frequency is 100kHz and the step change of the load R is from 50 Ω to 10 Ω. Further, the superior characteristics are obtained when the first gain, the second gain and the second cut-off frequency are relatively large, and the first cut-off frequency and the passing frequency are relatively low. Moreover, it is important that the gain strongly decreases at the second cut-off frequency because the upper band pass frequency range must be always less than half of the sampling frequency based on the sampling theory.
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LENUS (Irish Health Repository)
Maduemem, K
2017-06-01
We describe the case history of a 9-year-old boy who developed Stevens-Johnson syndrome (SJS) following concomitant use of valproic acid and lamotrigine. He presented with rash and fever several weeks after introduction of lamotrigine, having been on valproic acid for seizure disorder. SJS happens to be one of the rare adverse reactions of antiepilepsy drugs (AED). Management is mainly supportive with care escalation when necessary because of the significant morbidity.
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DC-Compensated Current Transformer †
Ripka, Pavel; Draxler, Karel; Styblíková, Renata
2016-01-01
Instrument current transformers (CTs) measure AC currents. The DC component in the measured current can saturate the transformer and cause gross error. We use fluxgate detection and digital feedback compensation of the DC flux to suppress the overall error to 0.15%. This concept can be used not only for high-end CTs with a nanocrystalline core, but it also works for low-cost CTs with FeSi cores. The method described here allows simultaneous measurements of the DC current component. PMID:26805830
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Reliability study of high gain DC-DC converters based on RRPP I-IIA ...
Indian Academy of Sciences (India)
J DIVYA NAVAMANI
2018-05-10
May 10, 2018 ... Energy Storage Modules (ESM), Propulsion Motor Mod- ules (PMM) and ... All Electric Ship (AES) is the best way to power all the loads in the ship ... also used to derive quadratic step down DC-DC converters. [6]. The attractive ...... Exhibition on Ecological Vehicles and Renewable Energies,. TamilNadu ...
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International Nuclear Information System (INIS)
Seo, Jun Ho; Park, Jin Myung; Hong, Sang Hee
2008-01-01
The influence of DC arc jets on the flow fields in a hybrid plasma torch is numerically analyzed by an integrated direct current-radio frequency (DC-RF) plasma model based on magneto-hydrodynamic formulations. The calculated results reveal that the increase in DC arc gas flow rate raises the axial flow velocity along the central column of the DC-RF hybrid plasma together with the enhanced backflow streams in the peripheral wall region. The temperature profiles on the torch exit plane are little affected due to the reheating process of the central column by the combined RF plasma. Accordingly, the exit enthalpy emitted from the DC-RF hybrid torch can be concentrated to the central column of the plasma and controlled by adjusting the DC arc gas flow rate. The swirl in the sheath gas flow turns out to have the opposite effect on the DC arc gas flow rate. The swirling motion of the sheath gas can reduce the back flows near the induction tube wall as well as the axial velocities in the central column of the plasma. Accordingly, the swirl in the sheath gas flow can be used for the functional operation of the DC-RF hybrid plasma along with the DC arc gas flow rate to suppress the back flows at the wall region and to reduce the excessive interactions between the DC arc jet and the ambient RF plasmas. The effects of DC input current on the flow fields of hybrid plasma are similar to those of the DC arc gas flow rate, but the axial velocities for the higher current relatively quickly decay along the centerline. This is in contrast to the increase in the axial velocity remaining in proportion to the increase in the DC arc gas flow rate all the way up to the exit of the DC-RF hybrid plasma. Accordingly, the present integrated numerical analysis suggests that the hybrid plasma field profiles and the entrainment of ambient air from the torch exit are controllable by adjusting the DC arc gas flow rate, the DC input current and swirl in the sheath gas flow taking advantage of
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... For Patients About ACOG Dilation and Curettage (D&C) Home For Patients Search FAQs Dilation and Curettage ( ... February 2016 PDF Format Dilation and Curettage (D&C) Special Procedures What is dilation and curettage (D& ...
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Ultrahigh-density trench cpacitors in silicon and their application to integrated DC-DC conversion
Roozeboom, F.; Bergveld, H.J.; Nowak, K.; Le Cornec, F.; Guiraud, L.; Bunel, C.; Iochem, S.; Ferreira, J.; Ledain, S.; Pieraerts, E.; Pommier, M.
2009-01-01
This paper addresses silicon-based integration of passive components applied to 3D integration with dies of other technologies within one package. Particularly, the development of high-density trench capacitors has enabled the realization of small-formfactor DC-DC converters. As illustration, an
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Spectral shaping of a randomized PWM DC-DC converter using maximum entropy probability distributions
CSIR Research Space (South Africa)
Dove, Albert
2017-01-01
Full Text Available maintaining constraints in a DC-DC converter is investigated. A probability distribution whose aim is to ensure maximal harmonic spreading and yet mainaint constraints is presented. The PDFs are determined from a direct application of the method of Maximum...
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Programmable dc motor controller
Hopwood, J. E.
1982-11-01
A portable programmable dc motor controller, with features not available on commercial instruments was developed for controlling fixtures during welding processes. The controller can be used to drive any dc motor having tachometer feedback and motor requirements not exceeding 30 volts, 3 amperes. Among the controller's features are delayed start time, upslope time, speed, and downslope time.
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DEFF Research Database (Denmark)
Bhaskar, Mahajan Sagar; Kulkarni, Rishi M.; Padmanaban, Sanjeevi Kumar
2016-01-01
In this paper hybrid non isolated/ non inverting Nx interleaved DC-DC multilevel Boost Converter for renewable energy applications is presented. The presented hybrid topology is derived from the conventional interleaved converter and the Nx Multilevel boost converter. In renewable energy...... applications, generated energy cannot be directly used at application end. In most of the cases it needs to be stepped up with DC-DC converter at operating voltage levels as per the requirement of the application. Though conventional boost converter can theoretically be used for this purpose, but obtaining...
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Padmanaban, Sanjeevikumar; Grandi, Gabriele; Blaabjerg, Frede; Wheeler, Patrick; Siano, Pierluigi; Hammami, Manel
2017-01-01
Classical DC-DC converters used in high voltage direct current (HVDC) power transmission systems, lack in terms of efficiency, reduced transfer gain and increased cost with sensor (voltage/current) numbers. Besides, the internal self-parasitic behavior of the power components reduces the output voltage and efficiency of classical HV converters. This paper deals with extra high-voltage (EHV) dc-dc boost converter by the application of voltage-lift technique to overcome the aforementioned defic...
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Direct switching control of DC-DC power electronic converters using hybrid system theory
Energy Technology Data Exchange (ETDEWEB)
Zhao, J.; Lin, F. [Wayne State Univ., Detroit, MI (United States). Dept. of Electrical and Computer Engineering; Wang, C. [Wayne State Univ., Detroit, MI (United States). Dept. of Electrical and Computer Engineering; Wayne State Univ., Detroit, MI (United States). Div. of Engineering Technology
2010-07-01
A direct switching control (DSC) scheme for power electronics converters was described. The system was designed for use in both traditional and renewable energy applications as well as in electric drive vehicles. The proposed control scheme was based on a detailed hybrid system converter model that used model predictive control (MPC), piecewise affine (PWA) approximations and constrained optimal control methods. A DC-DC converter was modelled as a hybrid machine. Switching among different modes of the DC-DC converter were modelled as discrete events controlled by the hybrid controller. The modelling scheme was applied to a Buck converter. The DSC was used to control the switch of the power converter based on a hybrid machine model. Results of the study showed that the method can be used to regulate output voltage and inductor currents. The method also provides fast transient responses and effectively regulates both currents and voltage. The controller can be used to provide immediate responses to dynamic disturbances and output voltage fluctuations. 23 refs., 7 figs.
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Not a Pound for Air-To-Ground: A Historiographical Analysis on the Genesis of the Multi-Role Fighter
2015-04-01
Robert M. Quadrennial Defense Review Report. Washington D.C.: Department of Defense, 2010. http://www.defense.gov/qdr/images...dvs=1417624228343~272 (accessed 2 Dec 2014) Stevens, Donald, Bruce Davis, William Stanley, Daniel Norton, Rae Starr, Dnaiel Raymer , John Gibson
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Informational model verification of ZVS Buck quasi-resonant DC-DC converter
Vakovsky, Dimiter; Hinov, Nikolay
2016-12-01
The aim of the paper is to create a polymorphic informational model of a ZVS Buck quasi-resonant DC-DC converter for the modeling purposes of the object. For the creation of the model is applied flexible open standards for setting, storing, publishing and exchange of data in distributed information environment. The created model is useful for creation of many and different by type variants with different configuration of the composing elements and different inner model of the examined object.
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DEFF Research Database (Denmark)
Larsen, Dennis Øland; Vinter, Martin; Jørgensen, Ivan Harald Holger
A switched capacitor dc-dc converter with frequency-planned control is presented. By splitting the output stage switches in eight segments the output voltage can be regulated with a combination of switching frequency and switch conductance. This allows for switching at predetermined frequencies, 31...
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A Novel Dual-input Isolated Current-Fed DC-DC Converter for Renewable Energy System
DEFF Research Database (Denmark)
Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.
2010-01-01
In this paper, a novel isolated current-fed DC-DC converter (boost-type) with two input power sources based on multi-transformer structure, which is suitable for fuel cells and super-capacitors hybrid energy system, is proposed and designed. With particular transformer windings connection strategy...
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International Nuclear Information System (INIS)
Feld, L.; Karpinski, W.; Klein, K.; Lipinski, M.; Preuten, M.; Rauch, M.; Schmitz, S.; Wlochal, M.
2016-01-01
The CMS collaboration has adopted a DC-DC conversion powering scheme for the Phase-1 Upgrade of its pixel detector. DC-DC buck converters with a conversion ratio of around 3 are installed on the support structures, outside of the sensitive tracking region, requiring a re-design of the low and high voltage distribution to the pixel modules. After several years of R and D, the project has entered the production phase. A total of 1800 DC-DC converters are being produced, and rigorous quality assurance and control is being employed during the production process. The testing program is outlined, results from mass production are presented and issues that have been encountered are described. In addition, two system level challenges, namely the choice of output voltage in the presence of large, load-dependent voltage drops, and the thermal management required to remove the heat load caused by the DC-DC converters, are discussed
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DEFF Research Database (Denmark)
Zhang, Zhe; Mira Albert, Maria del Carmen; Andersen, Michael A. E.
2017-01-01
This paper presents two configurations of dualinput (DI) or three-port (TPC) isolated dc-dc converters for hybrid renewable energy systems such as photovoltaics and batteries. These two converters are derived by integrating an interleaved boost converter and a single-active bridge converter...... and control perspective, distinct in operation principles, voltage/power transfer functions, loss distributions, soft-switching constraints, and power efficiency under the same operating conditions. Moreover, the inductor design differs greatly between these two cases. In this paper, a comprehensive...
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Analysis of a high power, resonant DC-DC converter for DC wind turbines
DEFF Research Database (Denmark)
Dincan, Catalin Gabriel; Kjær, Philip Carne; Chen, Yu-Hsing
2018-01-01
This paper is introducing a new method of operation for a series resonant converter, with intended application in megawatt high-voltage DC wind turbines. Compared to a frequency controlled series resonant converter operated in sub resonant mode, the method (entitled pulse removal technique) allows...
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High-Efficiency Photovoltaic System Using Partially-Connected DC-DC Converter
Uno, Masatoshi; Kukita, Akio; Tanaka, Koji
Power conversion electronics for photovoltaic (PV) systems are desired to operate as efficiently as possible to exploit the power generated by PV modules. This paper proposes a novel PV system in which a dc-dc converter is partially connected to series-connected PV modules. The proposed system achieves high power-conversion efficiency by reducing the passing power and input/output voltages of the converter. The theoretical operating principle was experimentally validated. Resultant efficiency performances of the proposed and conventional systems demonstrated that the proposed system was more efficient in terms of power conversion though the identical converter was used for the both systems.
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Very High Frequency Resonant DC/DC Converters for LED Lighting
DEFF Research Database (Denmark)
Madsen, Mickey Pierre; Knott, Arnold; Andersen, Michael A. E.
2013-01-01
This paper presents a very high frequency DC/DC converter for LED lighting. Several resonant topologies are compared and their usability discussed. At the end the resonant SEPIC converter is chosen based on the achievable power density and total bill of material. Simulations of a 51 MHz converter...... with 40 V input and 15 V output are made. The simulation shows possibility of achieving efficiency up to 87 % even with a HEXFET Power MOSFET. Three prototypes of the simulated converter are implemented showing good correlation with simulations. The prototypes have efficiencies up to 84 % and power...
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A THREE-PHASE BOOST DC-AC CONVERTER
African Journals Online (AJOL)
dc-ac converter (inverter) based on the dc-dc boost converters. ... Sliding mode controllers are designed to perform a robust control for the ... Computer simulations and spectral analysis demon- ... the conventional three-phase buck inverter,.
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DEFF Research Database (Denmark)
Haxthausen, Anne; Yong, Xia
1999-01-01
In this talk we present a method for linking the Duration Calculus together with the Timed RAISE Specification Language. Duration Calculus (DC) [ZHR91] is an interval-based real time logic, which can be used naturally in capturing and eliciting users' real time requirements in the form of constra......In this talk we present a method for linking the Duration Calculus together with the Timed RAISE Specification Language. Duration Calculus (DC) [ZHR91] is an interval-based real time logic, which can be used naturally in capturing and eliciting users' real time requirements in the form.......TRSL is a real-time extension of the RAISE Specification Language (RSL) [Rlg92] which together with its associated method [Rmg95]and tools has shown to be very useful in the industrial development of software systems. Therefore, a promising approach for the development of real-time systemscould be to use DC...... for high-level specifications of real-time requirementsand TRSL for specifying real-time implementations in the form of timed communicating concurrent processes.In order to link DC and TRSL together in a well-founded way, we formally define what it means for a TRSL process to satisfy a DC requirement...
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A Four-Phase High Voltage Conversion Ratio Bidirectional DC-DC Converter for Battery Applications
Directory of Open Access Journals (Sweden)
Li-Kun Xue
2015-06-01
Full Text Available This study presents a four-phase interleaved high voltage conversion ratio bidirectional DC-DC converter circuit based on coupled inductors and switched capacitors, which can eliminate the defects of conventional high voltage conversion ratio bidirectional DC-DC converters in terms of high-voltage/current stress, less efficiency and low-power limitation. Parallel channels are used to reduce current stress at the low-voltage side and series connected switched capacitors are used to enlarge voltage conversion ratio, reduce voltage stress and achieve auto current sharing. This paper proposes the operation principle, feature analysis and optimization design considerations. On this basis the objectives of high voltage conversion ratio, low voltage/current stress, high power density, high efficiency and high-power applications can be achieved. Some experimental results based on a 500 W prototype converter (24 V to 48 V at low-voltage side, 400 V at high-voltage side are given to verify the theoretical analysis and the effectiveness of the proposed converter.
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Jayaweera, H. M. P. C.; Muhtaroğlu, Ali
2016-11-01
A novel model based methodology is presented to determine optimal device parameters for the fully integrated ultra low voltage DC-DC converter for energy harvesting applications. The proposed model feasibly contributes to determine the maximum efficient number of charge pump stages to fulfill the voltage requirement of the energy harvester application. The proposed DC-DC converter based power consumption model enables the analytical derivation of the charge pump efficiency when utilized simultaneously with the known LC tank oscillator behavior under resonant conditions, and voltage step up characteristics of the cross-coupled charge pump topology. The verification of the model has been done using a circuit simulator. The optimized system through the established model achieves more than 40% maximum efficiency yielding 0.45 V output with single stage, 0.75 V output with two stages, and 0.9 V with three stages for 2.5 kΩ, 3.5 kΩ and 5 kΩ loads respectively using 0.2 V input.
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State trajectories used to observe and control dc-to-dc converters
Burns, W. W., III; Wilson, T. G.
1976-01-01
State-plane analysis techniques are employed to study the voltage stepup energy-storage dc-to-dc converter. Within this framework, an example converter operating under the influence of a constant on-time and a constant frequency controller is examined. Qualitative insight gained through this approach is used to develop a conceptual free-running control law for the voltage stepup converter which can achieve steady-state operation in one on/off cycle of control. Digital computer simulation data are presented to illustrate and verify the theoretical discussions presented.
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Design of an Input-Parallel Output-Parallel LLC Resonant DC-DC Converter System for DC Microgrids
Juan, Y. L.; Chen, T. R.; Chang, H. M.; Wei, S. E.
2017-11-01
Compared with the centralized power system, the distributed modularized power system is composed of several power modules with lower power capacity to provide a totally enough power capacity for the load demand. Therefore, the current stress of the power components in each module can then be reduced, and the flexibility of system setup is also enhanced. However, the parallel-connected power modules in the conventional system are usually controlled to equally share the power flow which would result in lower efficiency in low loading condition. In this study, a modular power conversion system for DC micro grid is developed with 48 V dc low voltage input and 380 V dc high voltage output. However, in the developed system control strategy, the numbers of power modules enabled to share the power flow is decided according to the output power at lower load demand. Finally, three 350 W power modules are constructed and parallel-connected to setup a modular power conversion system. From the experimental results, compared with the conventional system, the efficiency of the developed power system in the light loading condition is greatly improved. The modularized design of the power system can also decrease the power loss ratio to the system capacity.
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Considerations of Physical Design and Implementation for 5 MHz-100 W LLC Resonant DC-DC Converters
Directory of Open Access Journals (Sweden)
Akinori Hariya
2016-01-01
Full Text Available Recently, high power-density, high power-efficiency, and wide regulation range isolated DC-DC converters have been required. This paper presents considerations of physical design and implementation for wide regulation range MHz-level LLC resonant DC-DC converters. The circuit parameters are designed with 3–5 MHz-level switching frequency. Also, the physical parameters and the size of the planar transformer are optimized by using derived equations and finite element method (FEM with Maxwell 3D. Some experiments are done with prototype LLC resonant DC-DC converter using gallium nitride high electron mobility transistors (GaN-HEMTs; the input voltage is 42–53 V, the reference output voltage is 12 V, the load current is 8 A, the maximum switching frequency is about 5 MHz, the total volume of the circuit is 4.1 cm3, and the power density of the prototype converter is 24.4 W/cc.
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Design and implementation of current fed DC-DC converter for PHEV application using renewable source
Milind Metha, Manish; Tutki, Sanjay; Rajan, Aju; Elangovan, D.; Arunkumar, G.
2017-11-01
As the fossil fuels are depleting day by day, the use of renewable energy sources came into existence and they evolved a lot lately. To increase efficiency and productivity in the hybrid vehicles, the existence less efficient petroleum and diesel IC engines need to be replaced with the new and efficient converters with renewable energy sources. This has to be done in such a way that impacts three factors mainly: cost, efficiency and reliability. The PHEVs that have been launched and the upcoming PHEVs using converters with voltage range around 380V to 400V generated with power ranges between 2.4KW to 2.8KW. The basic motto of this paper is to design a prolific converter while considering the factor such as cost and size. In this paper, a two stage DC-DC converter is proposed and the proposed DC-DC converter is utilized to endeavour voltage from 24V (photovoltaic source) to a yield voltage of 400V and to meet the power demand of 250W, since only one panel is being used for this proposed paper. This paper discuss in detail about why and how the current fed DC-DC converter is utilized along with a voltage doubler, thus reducing transformer turns and thereby reducing overall size of the product. Simulation and hardware results have been presented along with calculations for duty cycle required for firing sequence for different values of transformer turns.
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Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis and Treatment With a Biologic: A Case Report.
Chong, Ian; Chao, Alice
2017-01-01
One of the most dangerous dermatologic emergencies is Stevens-Johnson Syndrome (SJS)/toxic epidermal necrolysis (TEN). Although a rare disease, it can often lead to significant mortality. In this case report, we present a 77-year-old man who developed a sloughing rash that was secondary to a nonsteroidal anti-inflammatory drug. In addition to the recommended supportive care, the patient was treated with etanercept, a new, less commonly used intervention. We provide a brief review of SJS/TEN. Nonsteroidal anti-inflammatory drugs are a rare cause of SJS/TEN, and additionally, the use of biologics is a novel treatment modality for SJS/TEN.
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Series-Connected High Frequency Converters in a DC Microgrid System for DC Light Rail Transit
Directory of Open Access Journals (Sweden)
Bor-Ren Lin
2018-01-01
Full Text Available This paper studies and presents a series-connected high frequency DC/DC converter connected to a DC microgrid system to provide auxiliary power for lighting, control and communication in a DC light rail vehicle. Three converters with low voltage and current stresses of power devices are series-connected with single transformers to convert a high voltage input to a low voltage output for a DC light rail vehicle. Thus, Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs with a low voltage rating and a turn-on resistance are adopted in the proposed circuit topology in order to decrease power losses on power switches and copper losses on transformer windings. A duty cycle control with an asymmetric pulse-width modulation is adopted to control the output voltage at the desired voltage level. It is also adopted to reduce switching losses on MOSFETs due to the resonant behavior from a leakage inductor of an isolated transformer and output capacitor of MOSFETs at the turn-on instant. The feasibility and effectiveness of the proposed circuit have been verified by a laboratory prototype with a 760 V input and a 24 V/60 A output.
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Guest Editorial Special Issue on Structured DC Microgrids
DEFF Research Database (Denmark)
Guerrero, Josep M.; Tan, Don F. D.
2017-01-01
With the development of dc coupled devices, such as photovoltaic generations, batteries, supercapacitors, LEDs, computers, and electronics equipment, low-voltage dc distribution networks, structured dc microgrids are emerging as a natural platform to integrate renewable energy sources. However...... in either series/parallel, forming a number of dc busses with different voltage levels. Recently, with the advance of new dc power technologies, several ongoing standards, alliances, and initiatives are bringing the possibility of developing future homes, offices, buildings, campuses, datacenters, ships......, satellites, aircrafts, and other electrical power systems to operate totally or dominantly in dc. Research is being carried out in both the system and component levels of modeling, control, and stability of structured dc microgrids. New high-efficiency topologies and protections are also key nontrivial...
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A new soft-switched high step-up DC-DC converter with dual coupled inductors
DEFF Research Database (Denmark)
Forouzesh, Mojtaba; Shen, Yanfeng; Yari, Keyvan
2017-01-01
This paper introduces a new efficient high step-up dc-dc converter with a shared input path and dual series coupled inductors at the output. This converter is suitable for high power applications due to its shared input current that puts low current stresses on the low voltage side switches...
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2010-12-23
...-1203; Directorate Identifier 2010-NM-168-AD] RIN 2120-AA64 Airworthiness Directives; McDonnell Douglas... amends Sec. 39.13 by adding the following new airworthiness directive (AD): McDonnell Douglas Corporation... Douglas Corporation Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), DC-9-87 (MD-87) and MD-88...
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CSIR Research Space (South Africa)
Coetzer, A
2016-01-01
Full Text Available The design and implementation of a bidirectional current-controlled voltage-regulated DC-DC converter is presented. The converter is required to connect a battery of electrochemical cells (the battery) to an asynchronous motor-drive unit via a...
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A high voltage gain quasi Z-source isolated DC/DC converter
DEFF Research Database (Denmark)
Siwakoti, Yam P.; Blaabjerg, Frede; Loh, Poh Chiang
2014-01-01
A compact quasi-Z-source DC/DC converter is presented with high voltage gain, isolated output, and improved efficiency. The improvements in size and performance were achieved by using a square wave inverter with only two output switches driving an isolating transformer in push-pull mode, followed...... by a voltage doubling output rectifier. The converter is well-suited to applications requiring a high voltage gain, especially renewable energy sources such as photovoltaic and fuel-cell power supplies. To demonstrate the converter's performance a prototype designed to output 400 V at 500 W was constructed...
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Four Quadrants Integrated Transformers for Dual-input Isolated DC-DC Converters
DEFF Research Database (Denmark)
Ouyang, Ziwei; Zhang, Zhe; Andersen, Michael A. E.
2012-01-01
A common limitation of power coupling effect in some known multiple-input dc-dc converters has been addressed in many literatures. In order to overcome this limitation, a new concept for decoupling the primary windings in the integrated multiple-winding transformers based on 3-dimensional (3D...... perpendicular primary windings, a name of “four quadrants integrated transformers” (FQIT) is therefore given to the proposed construction. Since the two primary windings are uncoupled, the FQIT allows the two input power stages to transfer the energy into the output load simultaneously or at any...
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High Current Planar Transformer for Very High Efficiency Isolated Boost DC-DC Converters
DEFF Research Database (Denmark)
Pittini, Riccardo; Zhang, Zhe; Andersen, Michael A. E.
2014-01-01
This paper presents a design and optimization of a high current planar transformer for very high efficiency dc-dc isolated boost converters. The analysis considers different winding arrangements, including very high copper thickness windings. The analysis is focused on the winding ac-resistance a......This paper presents a design and optimization of a high current planar transformer for very high efficiency dc-dc isolated boost converters. The analysis considers different winding arrangements, including very high copper thickness windings. The analysis is focused on the winding ac......-resistance and transformer leakage inductance. Design and optimization procedures are validated based on an experimental prototype of a 6 kW dcdc isolated full bridge boost converter developed on fully planar magnetics. The prototype is rated at 30-80 V 0-80 A on the low voltage side and 700-800 V on the high voltage side...... with a peak efficiency of 97.8% at 80 V 3.5 kW. Results highlights that thick copper windings can provide good performance at low switching frequencies due to the high transformer filling factor. PCB windings can also provide very high efficiency if stacked in parallel utilizing the transformer winding window...
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Steven johnsons syndrome and toxic epidermal necrolysis: A review
Directory of Open Access Journals (Sweden)
Sri ram Anne
2014-12-01
Full Text Available Toxic epidermal necrolysis (TEN and Stevens Johnson Syndrome (SJS are severe adverse cutaneous drug reactions that predominantly involve the skin and mucous membranes. They are characterized by mucocutaneous tenderness and typically hemorrhagic erosions, erythema and more or less severe epidermal detachment presenting as blisters and areas of denuded skin. Drugs are assumed or identified as the main cause of SJS/TEN in most cases, but Mycoplasma pneumoniae and Herpes simplex virus infections are well documented causes alongside rare cases in which the etiology remains unknown. Several drugs are at "high" risk of inducing TEN/SJS including: Allopurinol, Trimethoprim-sulfamethoxazole and other sulfonamide-antibiotics, aminopenicillins, cephalosporins, quinolones, carbamazepine, phenytoin, phenobarbital and NSAID's of the oxicam-type. Differential diagnosis includes linear IgA dermatosis and paraneoplastic pemphigus, pemphigus vulgaris and bullous pemphigoid, acute generalized exanthematous pustulosis (AGEP, disseminated fixed bullous drug eruption and staphyloccocal scalded skin syndrome (SSSS. Due to the high risk of mortality, management of patients with SJS/TEN requires rapid diagnosis, identification and interruption of the culprit drug, specialized supportive care ideally in an intensive care unit, and consideration of immunomodulating agents such as high-dose intravenous immunoglobulin therapy.
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Síndrome de Stevens-Johnson e necrólise epidérmica tóxica
Coelho, Inês Dionísio
2013-01-01
Trabalho final de mestrado integrado em Medicina (Dermatologia), apresentado à Faculdade de Medicina da Universidade de Coimbra. A Síndrome de Stevens-Johnson (SSJ) e a necrólise epidérmica tóxica (NET) são reacções mucocutâneas raras consideradas emergências médicas, podendo tornar-se fatais. Constituem dois extremos do mesmo espectro clínico das reacções cutâneas severas adversas a fármacos com necrose epidérmica, diferindo apenas na extensão do descolamento epidérmico. A gra...
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Directory of Open Access Journals (Sweden)
F. Azma
2015-06-01
Full Text Available This paper develops an effective control framework for DC voltage control and power-sharing of multi-terminal DC (MTDC grids based on an optimal power flow (OPF procedure and the voltage-droop control. In the proposed approach, an OPF algorithm is executed at the secondary level to find optimal reference of DC voltages and active powers of all voltage-regulating converters. Then, the voltage droop characteristics of voltage-regulating converters, at the primary level, are tuned based on the OPF results such that the operating point of the MTDC grid lies on the voltage droop characteristics. Consequently, the optimally-tuned voltage droop controller leads to the optimal operation of the MTDC grid. In case of variation in load or generation of the grid, a new stable operating point is achieved based on the voltage droop characteristics. By execution of a new OPF, the voltage droop characteristics are re-tuned for optimal operation of the MTDC grid after the occurrence of the load or generation variations. The results of simulation on a grid inspired by CIGRE B4 DC grid test system demonstrate efficient grid performance under the proposed control strategy.
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DEFF Research Database (Denmark)
Haxthausen, Anne Elisabeth; Yong, X.
2000-01-01
in a method for real-time developments. An operational semantics with behavior is specified for TRSL. It is defined what its means for a TRSL process to satisfy a DC requirement, and a method for verifying whether the satisfaction relation holds or not is provided. Our contribution also demonstrates a general......Duration Calculus (DC) is an interval-based real-time logic, which can be used in capturing and eliciting users' real-time requirements. The Timed RAISE Specification Language (TRSL) is an extension of the RAISE Specification Language with real-time features. This paper links DC and TRSL together...
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National Aeronautics and Space Administration — The Space Micro Arizona State University (ASU) team will develop an all-digitally controlled, wide temperature range point-of-load switch-mode DC-DC regulator core...
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Open-circuit fault detection and tolerant operation for a parallel-connected SAB DC-DC converter
DEFF Research Database (Denmark)
Park, Kiwoo; Chen, Zhe
2014-01-01
This paper presents an open-circuit fault detection method and its tolerant control strategy for a Parallel-Connected Single Active Bridge (PCSAB) dc-dc converter. The structural and operational characteristics of the PCSAB converter lead to several advantages especially for high power applicatio...
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Hierarchical Power Sharing Control in DC Microgrids
DEFF Research Database (Denmark)
Peyghami, Saeed; Mokhtari, Hossein; Blaabjerg, Frede
2016-01-01
Because of the advances in power electronics, DC-based power systems, have been used in industrial applications such as data centers [18], space applications [10], aircraft [12], offshore wind farms, electric vehicles [56], DC home systems [5, 20], and high-voltage DC transmission systems...
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2010-07-01
... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 9-10 Series Airplanes, DC-9-30 Series... previously to all known U.S. owners and operators of the McDonnell Douglas Corporation airplanes identified... INFORMATION: On July 15, 2009, we issued AD 2009-15-16, which applies to all McDonnell Douglas Model DC-9-10...
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Experimental study of dynamic behaviors and routes to chaos in DC-DC boost converters
International Nuclear Information System (INIS)
Cafagna, D.; Grassi, G.
2005-01-01
This paper illustrates an experimental study of a current-programmed DC-DC boost converter, with the aim of investigating possible pathways through which the converter may enter chaos. In particular, based on experimental measurements, it is shown that variations of input voltage and reference current can generate periodic, subharmonic, quasi-periodic and chaotic behaviors
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Halbach array DC motor/generator
Merritt, B.T.; Dreifuerst, G.R.; Post, R.F.
1998-01-06
A new configuration of DC motor/generator is based on a Halbach array of permanent magnets. This motor does not use ferrous materials so that the only losses are winding losses and losses due to bearings and windage. An ``inside-out`` design is used as compared to a conventional motor/generator design. The rotating portion, i.e., the rotor, is on the outside of the machine. The stationary portion, i.e., the stator, is formed by the inside of the machine. The rotor contains an array of permanent magnets that provide a uniform field. The windings of the motor are placed in or on the stator. The stator windings are then ``switched`` or ``commutated`` to provide a DC motor/generator much the same as in a conventional DC motor. The commutation can be performed by mechanical means using brushes or by electronic means using switching circuits. The invention is useful in electric vehicles and adjustable speed DC drives. 17 figs.
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Halbach array DC motor/generator
Merritt, Bernard T.; Dreifuerst, Gary R.; Post, Richard F.
1998-01-01
A new configuration of DC motor/generator is based on a Halbach array of permanent magnets. This motor does not use ferrous materials so that the only losses are winding losses and losses due to bearings and windage. An "inside-out" design is used as compared to a conventional motor/generator design. The rotating portion, i.e., the rotor, is on the outside of the machine. The stationary portion, i.e., the stator, is formed by the inside of the machine. The rotor contains an array of permanent magnets that provide a uniform field. The windings of the motor are placed in or on the stator. The stator windings are then "switched" or "commutated" to provide a DC motor/generator much the same as in a conventional DC motor. The commutation can be performed by mechanical means using brushes or by electronic means using switching circuits. The invention is useful in electric vehicles and adjustable speed DC drives.
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Bifurcation Analysis of a DC-DC Bidirectional Power Converter Operating with Constant Power Loads
Cristiano, Rony; Pagano, Daniel J.; Benadero, Luis; Ponce, Enrique
Direct current (DC) microgrids (MGs) are an emergent option to satisfy new demands for power quality and integration of renewable resources in electrical distribution systems. This work addresses the large-signal stability analysis of a DC-DC bidirectional converter (DBC) connected to a storage device in an islanding MG. This converter is responsible for controlling the balance of power (load demand and generation) under constant power loads (CPLs). In order to control the DC bus voltage through a DBC, we propose a robust sliding mode control (SMC) based on a washout filter. Dynamical systems techniques are exploited to assess the quality of this switching control strategy. In this sense, a bifurcation analysis is performed to study the nonlinear stability of a reduced model of this system. The appearance of different bifurcations when load parameters and control gains are changed is studied in detail. In the specific case of Teixeira Singularity (TS) bifurcation, some experimental results are provided, confirming the mathematical predictions. Both a deeper insight in the dynamic behavior of the controlled system and valuable design criteria are obtained.
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Energy Technology Data Exchange (ETDEWEB)
Khan, U.A.; Shin, W.J.; Seong, J.K.; Oh, S.H.; Lee, S.H. [School of Electrical Engineering and Computer Science, Hanyang University, Ansan-Shi, Gyeonggi-do 426-791 (Korea, Republic of); Lee, B.W., E-mail: bangwook@hanyang.ac.kr [School of Electrical Engineering and Computer Science, Hanyang University, Ansan-Shi, Gyeonggi-do 426-791 (Korea, Republic of)
2011-11-15
We modeled DC SFCL by use of SimPowerSystem blocks. We examine the DC fault current limitation in low voltage DC distribution networks. SFCL's affects at critical points were measured. SFCL installed at the substation rectifier branch resulted in abnormal increase of fault current. The strategic location of SFCL is the point of integration of the PV plant with the power grid. DC fault current limitation in DC distribution network is one of the critical issues which need to be taken care of before they can be practically implemented. High temperature superconductors could be efficiently installed to cope with the problem of DC fault currents. In this paper, a generalized DC high temperature superconducting fault current limiter (SFCL) is modeled by integrating Simulink and SimPowerSystem blocks. This model is designed for limiting DC fault currents in low voltage DC distribution networks. A DC microgrid having a low voltage DC distribution network, an integrated photovoltaic plant and domestic customer load is modeled. Transient analysis of the DC microgrid is performed by generating fault and measuring DC fault currents at critical points. The designed DC SFCL is placed at different strategic locations in DC microgrid and fault current limitation performance of DC SFCL in DC microgrid has been analyzed. Moreover, the affects of rapid impedance changing in the distribution network due to the fault followed by DC SFCL activation is investigated. Finally, the best suitable position and affects of DC SFCL in a DC microgrid along with suggestions for implementation have been proposed.
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International Nuclear Information System (INIS)
Khan, U.A.; Shin, W.J.; Seong, J.K.; Oh, S.H.; Lee, S.H.; Lee, B.W.
2011-01-01
We modeled DC SFCL by use of SimPowerSystem blocks. We examine the DC fault current limitation in low voltage DC distribution networks. SFCL's affects at critical points were measured. SFCL installed at the substation rectifier branch resulted in abnormal increase of fault current. The strategic location of SFCL is the point of integration of the PV plant with the power grid. DC fault current limitation in DC distribution network is one of the critical issues which need to be taken care of before they can be practically implemented. High temperature superconductors could be efficiently installed to cope with the problem of DC fault currents. In this paper, a generalized DC high temperature superconducting fault current limiter (SFCL) is modeled by integrating Simulink and SimPowerSystem blocks. This model is designed for limiting DC fault currents in low voltage DC distribution networks. A DC microgrid having a low voltage DC distribution network, an integrated photovoltaic plant and domestic customer load is modeled. Transient analysis of the DC microgrid is performed by generating fault and measuring DC fault currents at critical points. The designed DC SFCL is placed at different strategic locations in DC microgrid and fault current limitation performance of DC SFCL in DC microgrid has been analyzed. Moreover, the affects of rapid impedance changing in the distribution network due to the fault followed by DC SFCL activation is investigated. Finally, the best suitable position and affects of DC SFCL in a DC microgrid along with suggestions for implementation have been proposed.
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A DC-DC Converter with Wide Input Voltage Range for Fuel Cell and Supercapacitor Application
DEFF Research Database (Denmark)
Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael Andreas E.
2009-01-01
This paper proposes a novel phase-shift plus duty cycle controlled hybrid bi-directional DC-DC converter based on fuel cells and supercapacitors. The described converter employs two high frequency transformers to couple the half-bridge and full-bridge circuits together in the primary side...
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Step-Up Partial Power DC-DC Converters for Two-Stage PV Systems with Interleaved Current Performance
Directory of Open Access Journals (Sweden)
Jaime Wladimir Zapata
2018-02-01
Full Text Available This work presents a partial power converter allowing us to obtain, with a single DC-DC converter, the same feature as the classical interleaved operation of two converters. More precisely, the proposed topology performs similarly as the input-parallel output-series (IPOS configuration reducing the current ripple at the input of the system and dividing the individual converters power rating, compared to a single converter. The proposed topology consists of a partial DC-DC converter processing only a fraction of the total power, thus allowing high efficiency. Experimental results are provided to validate the proposed converter topology with a Flyback-based 100 W test bench with a transformer turns ratio n 1 = n 2 . Experimental results show high performances reducing the input current ripple around 30 % , further increasing the conversion efficiency.
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DC8 and DC13 var genes associated with severe malaria bind avidly to diverse endothelial cells.
Directory of Open Access Journals (Sweden)
Marion Avril
Full Text Available During blood stage infection, Plasmodium falciparum infected erythrocytes (IE bind to host blood vessels. This virulence determinant enables parasites to evade spleen-dependent killing mechanisms, but paradoxically in some cases may reduce parasite fitness by killing the host. Adhesion of infected erythrocytes is mediated by P. falciparum erythrocyte membrane protein 1 (PfEMP1, a family of polymorphic adhesion proteins encoded by var genes. Whereas cerebral binding and severe malaria are associated with parasites expressing DC8 and DC13 var genes, relatively little is known about the non-brain endothelial selection on severe malaria adhesive types. In this study, we selected P. falciparum-IEs on diverse endothelial cell types and demonstrate that DC8 and DC13 var genes were consistently among the major var transcripts selected on non-brain endothelial cells (lung, heart, bone marrow. To investigate the molecular basis for this avid endothelial binding activity, recombinant proteins were expressed from the predominant upregulated DC8 transcript, IT4var19. In-depth binding comparisons revealed that multiple extracellular domains from this protein bound brain and non-brain endothelial cells, and individual domains largely did not discriminate between different endothelial cell types. Additionally, we found that recombinant DC8 and DC13 CIDR1 domains exhibited a widespread endothelial binding activity and could compete for DC8-IE binding to brain endothelial cells, suggesting they may bind the same host receptor. Our findings provide new insights into the interaction of severe malaria adhesive types and host blood vessels and support the hypothesis that parasites causing severe malaria express PfEMP1 variants with a superior ability to adhere to diverse endothelial cell types, and may therefore endow these parasites with a growth and transmission advantage.
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Directory of Open Access Journals (Sweden)
P. Kowstubha
2016-12-01
Full Text Available Performance Analysis of Pulse Analog Control Schemes, predominantly Pulse-Width Modulation (PWM and Pulse-Position Modulation (PPM for LLC resonant DC/DC converter suitable in portable applications is addressed in this paper. The analysis is done for closed loop performance, frequency domain performance, primary and secondary side conduction losses and soft commutation using PSIM 6.0 software and observed that PPM scheme provides better performance at high input voltage with a good selectivity of frequency over a wide range of line and load variations. The performance of LLC resonant DC/DC converter is demonstrated using PPM scheme for a design specifications of 12 V, 5 A output.
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State-plane analysis of zero-voltage-switching resonant dc/dc power converters
Kazimierczuk, Marian K.; Morse, William D.
The state-plane analysis technique for the zero-voltage-switching resonant dc/dc power converter family of topologies, namely the buck, boost, buck-boost, and Cuk converters is established. The state plane provides a compression of information that allows the designer to uniquely examine the nonlinear dynamics of resonant converter operation. Utilizing the state plane, resonant converter modes of operation are examined and the switching frequencies are derived for the boundaries between these modes, including the boundary of energy conversion.
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Cost-based droop scheme for DC microgrid
DEFF Research Database (Denmark)
Nutkani, Inam Ullah; Wang, Peng; Loh, Poh Chiang
2014-01-01
voltage level, less on optimized operation and control of generation sources. The latter theme is perused in this paper, where cost-based droop scheme is proposed for distributed generators (DGs) in DC microgrids. Unlike traditional proportional power sharing based droop scheme, the proposed scheme......-connected operation. Most importantly, the proposed scheme can reduce overall total generation cost in DC microgrids without centralized controller and communication links. The performance of the proposed scheme has been verified under different load conditions.......DC microgrids are gaining interest due to higher efficiencies of DC distribution compared with AC. The benefits of DC systems have been widely researched for data centers, IT facilities and residential applications. The research focus, however, has been more on system architecture and optimal...
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DEFF Research Database (Denmark)
Mostaan, Ali; Alizadeh, Ebrahim; Soltani, Mohsen
2014-01-01
and the voltage transfer gain is obtained. It is also demonstrated that the voltage stress on all semiconductor devices is restricted to input voltage which allows the utilization of a power switch with lower drain source resistance. In order to further increase the voltage gain another switched capacitor voltage......Novel step-up DC/DC converter is introduced in this paper. This converter is realized with adding the switched capacitor voltage multiplier cell to the three switch step-down DC/DC converter that has been proposed in the literature. The proposed converter is analyzed in the steady state...
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Circuit description of unipolar DC-to-DC converters for APS storage ring quadrupoles and sextupoles
International Nuclear Information System (INIS)
McGhee, D.G.
1993-01-01
This paper describes the control, interlock, and power circuits for 680 unipolar switch mode DC-to-DC converters used to regulate the Advanced Photon Sources (APS's) storage ring quadrupole and sextupole magnet currents. Quadrupole current stability is ± 6x10 -5 and the sextupole current stability is ±3x10 -4 . The stability is obtained with pulse width modulation, operating at a switching frequency of 20kHz with full current switching. The converters are housed in 200 cabinets located on top of the storage ring tunnel. Raw DC power is distributed from 80 AC-to-DC power supplies, four at each of 20 locations around the storage ring. Voltages, currents, and temperatures are computer monitored and logged for the converters and magnets. All converters and magnets are water cooled with the flow and pressure monitored at the inlet and outlet of groups. Water is interlocked with the raw power supplies and not the individual converters
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Sudhakar, N.; Rajasekar, N.; Akhil, Saya; Jyotheeswara Reddy, K.
2017-11-01
The boost converter is the most desirable DC-DC power converter for renewable energy applications for its favorable continuous input current characteristics. In other hand, these DC-DC converters known as practical nonlinear systems are prone to several types of nonlinear phenomena including bifurcation, quasiperiodicity, intermittency and chaos. These undesirable effects has to be controlled for maintaining normal periodic operation of the converter and to ensure the stability. This paper presents an effective solution to control the chaos in solar fed DC-DC boost converter since the converter experiences wide range of input power variation which leads to chaotic phenomena. Controlling of chaos is significantly achieved using optimal circuit parameters obtained through Nelder-Mead Enhanced Bacterial Foraging Optimization Algorithm. The optimization renders the suitable parameters in minimum computational time. The results are compared with the traditional methods. The obtained results of the proposed system ensures the operation of the converter within the controllable region.
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Constructivism as the Framework for International Orders
2016-09-01
idea that each kingdom had a right to sovereign control of its territory, laying the groundwork for our modern concept of the state.5 These shared...Washington, DC: NDU Press, 2013), Chapter 1 “Deviant Globalization” by Nils Gilman, Jesse Goldhammer, and Steven Weber , 3.
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DEFF Research Database (Denmark)
Blaabjerg, Frede; Aquila, A. Dell; Liserre, Marco
2004-01-01
of dc/dc converters via a 50 Hz frequency-shift. The input admittance is calculated and measured for two study examples (a three-phase active rectifier and a single-phase photovoltaic inverter). These examples show that the purpose of a well designed controller for grid-connected converters......A systematic approach to study dc/ac and ac/dc converters without the use of synchronous transformation is proposed. The use of a frequency-shift technique allows a straightforward analysis of single-phase and three-phase systems. The study of dc/ac and of ac/dc converters is reported to the study...... is to minimize the input admittance in order to make the grid converter more robust to grid disturbance....
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DEFF Research Database (Denmark)
Schaltz, Erik; Li, Zhihao; Onar, Omer
2009-01-01
Battery/Ultra-capacitor based electrical vehicles (EV) combine two energy sources with different voltage levels and current characteristics. This paper focuses on design and control of a multiple input DC/DC converter, to regulate output voltage from different inputs. The proposed multi-input con......Battery/Ultra-capacitor based electrical vehicles (EV) combine two energy sources with different voltage levels and current characteristics. This paper focuses on design and control of a multiple input DC/DC converter, to regulate output voltage from different inputs. The proposed multi...
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Efendi, Moh. Zaenal; Windarko, Novie Ayub; Amir, Moh. Faisal
2013-01-01
This paper presents a design and implementation of a converter which has a high power factor for battery charger application. The converter is a combination of a SEPIC converter and a full-bridge DC-DC converter connected in two stages of series circuit. The SEPIC converter works in discontinuous conduction mode and it serves as a power factor corrector so that the shape of input current waveform follows the shape of input voltage waveform. The full-bridge DC-DC converter serves as a regulato...
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DEFF Research Database (Denmark)
Liu, Dong; Deng, Fujin; Zhang, Qi
2018-01-01
The asymmetrical modulation strategy is widely used in various types of three-level (TL) DC/DC converters, while the current imbalance among the power switches is one of the important issues. In this paper, a novel periodically swapping modulation (PSM) strategy is proposed for balancing the power...... switches’ currents in various types of TL DC/DC converters. In the proposed PSM strategy, the driving signals of the switch pairs are swapped periodically, which guarantees that the currents through the power switches are kept balanced in every two switching periods. Therefore, the proposed PSM...... strategy can effectively improve the reliability of the converter by balancing the power losses and thermal stresses among the power switches. The operation principle and performances of the proposed PSM strategy are analyzed in detail. Finally, the simulation and experimental results are presented...
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FY07 NRL DoD High Performance Computing Modernization Program Annual Reports
2008-09-05
41 Mark R. Pederson ,1 Tunna Baruah,2 Steven Richardson,3 Rajendre Zope,1 and Reeshemah Allen1 1Naval Research Laboratory, Washington, DC...DC vii Acoustic Propagation in Littoral Sub-Mesoscale Model Environments.....................61 Roger M. Oba,1 Colin Shen,1 Patrick...R ea ct io n ra te , K gm ol e/ m 1 s ec ( l ef t p ic tu re ) 12 Title: Simulations of the Ionosphere and Magnetosphere Author(s): S. P
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Distributed maximum power point tracking in photovoltaic applications: active bypass DC/DC converter
Directory of Open Access Journals (Sweden)
Carlos Andrés Ramos-Paja
2012-01-01
Full Text Available Se propone una estructura de desvío activo para maximizar la producción de potencia en sistemas fotovoltaicos bajo condiciones irregulares de operación, comparando su eficiencia con soluciones individuales y distribuidas basadas en convertidores DC/DC convencionales. Los análisis y simulaciones realistas demuestran las ventajas del nuevo convertidor de desvío activo sobre soluciones basadas en convertidores Boost, Buck y Buck-Boost.
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Gilbert ja George lasevad oma kunstiteose alla laadida
2007-01-01
9.05.2007 öösel on kõigil soovijail võimalik tasuta interneti vahendusel omandada Londonis tegutseva kunstnikepaari Gilbert & George (Gilbert Proesch ja George Passmore) teos "Planed". Aadressid: www.bbc.co.uk/imagine ja www.guardian.co.uk/art
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Silva-Ortigoza, R.; Silva-Ortigoza, G.; Hernandez-Guzman, V. M.; Saldana-Gonzalez, G.; Marcelino-Aranda, M.; Marciano-Melchor, M.
2012-01-01
We introduce a dc/dc boost power converter as a didactic prototype intended to support courses on electric circuit analysis experimentally. The corresponding mathematical model is obtained, the converter is designed and an experimental setup is described, constructed and tested. Simplicity of construction as well as low cost of components renders…
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A review on DC/DC converter architectures for power fuel cell applications
International Nuclear Information System (INIS)
Kolli, Abdelfatah; Gaillard, Arnaud; De Bernardinis, Alexandre; Bethoux, Olivier; Hissel, Daniel; Khatir, Zoubir
2015-01-01
Highlights: • Different DC/DC power converter topologies for Fuel Cell systems are presented. • Advantages and drawbacks of the DC/DC power converter topologies are detailed. • Wide-BandGap semiconductors are attractive candidates for design of converters. • Wide-BandGap semiconductors improve efficiency and thermal limits of converters. • Different semiconductor technologies are assessed. - Abstract: Fuel cell-based power sources are attractive devices. Through multi-stack architecture, they offer flexibility, reliability, and efficiency. Keys to accessing the market are simplifying its architecture and each components. These include, among others, the power converter enabling the output voltage regulation. This article focuses on this specific component. The present paper gives a comprehensive overview of the power converter interfaces potentially favorable for the automotive, railways, aircrafts and small stationary domains. First, with respect to the strategic development of a modular design, it defines the specifications of a basic interface. Second, it inventories the best architecture opportunities with respect to these requirements. Based on this study, it fully designs a basic module and points out the outstanding contribution of the new developed silicon carbide switch technology. In conclusion, this review article exhibits the importance of choosing the right power converter architecture and the related technology. In this context it is highlighted that the output power interface can be efficient, compact and modular. In addition, its features enable a thermal compatibility with many ways of integrating this component in the global fuel cell based power source.
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A single-phase embedded Z-source DC-AC inverter.
Kim, Se-Jin; Lim, Young-Cheol
2014-01-01
In the conventional DC-AC inverter consisting of two DC-DC converters with unipolar output capacitors, the output capacitor voltages of the DC-DC converters must be higher than the DC input voltage. To overcome this weakness, this paper proposes a single-phase DC-AC inverter consisting of two embedded Z-source converters with bipolar output capacitors. The proposed inverter is composed of two embedded Z-source converters with a common DC source and output AC load. Though the output capacitor voltages of the converters are relatively low compared to those of a conventional inverter, an equivalent level of AC output voltages can be obtained. Moreover, by controlling the output capacitor voltages asymmetrically, the AC output voltage of the proposed inverter can be higher than the DC input voltage. To verify the validity of the proposed inverter, experiments were performed with a DC source voltage of 38 V. By controlling the output capacitor voltages of the converters symmetrically or asymmetrically, the proposed inverter can produce sinusoidal AC output voltages. The experiments show that efficiencies of up to 95% and 97% can be achieved with the proposed inverter using symmetric and asymmetric control, respectively.
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Power Quality in DC Power Distribution Systems and Microgrids
Directory of Open Access Journals (Sweden)
Stephen Whaite
2015-05-01
Full Text Available This review paper discusses power quality considerations for direct current (DC electric power distribution systems, particularly DC microgrids. First, four selected sample DC architectures are discussed to provide motivation for the consideration of power quality in DC systems. Second, a brief overview of power quality challenges in conventional alternating current (AC distribution systems is given to establish the field of power quality. Finally, a survey of literature addressing power quality issues in DC systems is presented, and necessary power quality considerations in DC distribution system design and operation are discussed.
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Family of Step-up DC/DC Converters with Fast Dynamic Response for Low Power Applications
DEFF Research Database (Denmark)
N. Soltani, Mohsen; Mostaan, Ali; Siwakoti, Yam Prasad
2016-01-01
This study presents a family of novel step-up DC/DC converters which do not have a right half plane zero in their transfer function resulting in faster dynamic behaviour of the converters under the load variation. In addition, the voltage stress on all the active switches and diodes is as low...
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Ultra-Step-Up DC-DC Converter with Integrated Autotransformer and Coupled Inductor
DEFF Research Database (Denmark)
Siwakoti, Yam Prasad; Blaabjerg, Frede; Loh, Poh Chiang
2016-01-01
This paper introduces a new single-switch nonisolated dc-dc converter with very high voltage transfer ratio and reduced semiconductor voltage stress. The converter utilizes an integrated autotransformer and a coupled inductor on the same core to achieve a high step-up voltage gain without extreme...... duty cycle. Further, an integrated passive regenerative circuit recycles the leakage energy of the coupled magnetics and transfer the leakage energy to the load, which helps to avoid high voltage spikes across the switch. This feature along with low stress on the switching device enables the designer...
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Simultaneous distribution of AC and DC power
Polese, Luigi Gentile
2015-09-15
A system and method for the transport and distribution of both AC (alternating current) power and DC (direct current) power over wiring infrastructure normally used for distributing AC power only, for example, residential and/or commercial buildings' electrical wires is disclosed and taught. The system and method permits the combining of AC and DC power sources and the simultaneous distribution of the resulting power over the same wiring. At the utilization site a complementary device permits the separation of the DC power from the AC power and their reconstruction, for use in conventional AC-only and DC-only devices.
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Directory of Open Access Journals (Sweden)
Wenzheng Xu
2017-10-01
Full Text Available Phase-shifted converters are practically important to provide high conversion efficiencies through soft-switching techniques. However, the limitation on a resonant inductor current in the converters often leads to a non-fulfillment of the requirement of minimum load current. This paper presents a new power electronics control technique to enable the dual features of bi-directional power flow and an extended load range for soft-switching in phase-shift-controlled DC-DC converters. The proposed technique utilizes two identical full bridge converters and inverters in conjunction with a new control logic for gate-driving signals to facilitate both Zero Current Switching (ZCS and Zero Voltage Switching (ZVS in a single phase-shift-controlled DC-DC converter. The additional ZCS is designed for light load conditions at which the minimum load current cannot be attained. The bi-directional phase-shift-controlled DC-DC converter can implement the function of synchronous rectification. Its fast dynamic response allows for quick energy recovery during the regenerative braking of traction systems in electrified trains.
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Multi-cell DC-DC converters : modelling, analysis and control
International Nuclear Information System (INIS)
Feki, M.; El Aroudi, A.; Robert, B.G.M.
2011-01-01
This paper is devoted to modeling of a two-cell DC/DC buck converter, to the analysis of its behavior and to the design of control methods that yield to improve its performances. Various numerical simulations and dynamical aspects of this system are illustrated in the time domain and in the parameter space. Without control, the system may present many undesirable behaviors such as sub-harmonics and chaotic oscillations. The proposed controllers are able to widen the stability range of the system. Optimum values of parameters giving rise to fast response while maintaining stable periodic behavior are given in closed form. However, it is detected that in a certain region of the parameter space, the stabilized periodic orbit may coexist with a chaotic attractor. Boundary between basins of attraction are obtained by means of numerical simulations.
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DEFF Research Database (Denmark)
Liu, Dong; Deng, Fujin; Gong, Zheng
2017-01-01
In this paper, the input-parallel output-parallel (IPOP) three-level (TL) DC/DC converters associated with the interleaving control strategy are proposed for minimizing and balancing the capacitor ripple currents. The proposed converters consist of two four-switch half-bridge three-level (HBTL) DC...
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Matias, Mariana Santos; de Sousa, Bruna Barbosa; da Cunha Pereira, Déborah Fernanda; Dias, Edigar Henrique Vaz; Mamede, Carla Cristine Neves; de Queiroz, Mayara Ribeiro; Silva, Anielle Christine Almeida; Dantas, Noelio Oliveira; Soares, Andreimar Martins; de Oliveira Costa, Júnia; de Oliveira, Fábio
2017-01-01
Snake venoms are a complex mixture of proteins, organic and inorganic compounds. Some of these proteins, enzymatic or non-enzymatic ones, are able to interact with platelet receptors, causing hemostatic disorders. The possible therapeutic potential of toxins with antiplatelet properties may arouse interest in the pharmacological areas. The present study aimed to purify and characterize an antiplatelet DC protein from Bothrops alternatus snake venom. The protein, called BaltDC (DC protein from B. alternatus snake venom), was purified by a combination of ion-exchange chromatography on DEAE-Sephacel column and gel filtration on Sephadex G-75. The molecular mass was estimated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE). The amino acid sequence of the N-terminal region was carried out by Edman degradation method. Platelet aggregation assays were performed in human platelet-rich plasma (PRP). Infrared (IR) spectroscopy was used in order to elucidate the interactions between BaltDC and platelet membrane. BaltDC ran as a single protein band on SDS-PAGE and showed apparent molecular mass of 32 kDa under reducing or non-reducing conditions. The N-terminal region of the purified protein revealed the amino acid sequence IISPPVCGNELLEVGEECDCGTPENCQNECCDA, which showed identity with other snake venom metalloproteinases (SVMPs). BaltDC was devoid of proteolytic, hemorrhagic, defibrinating or coagulant activities, but it showed a specific inhibitory effect on platelet aggregation induced by ristocetin and epinephrine in PRP. IR analysis spectra strongly suggests that PO 3 2- groups, present in BaltDC, form hydrogen bonds with the PO 2 - groups present in the non-lipid portion of the membrane platelets. BaltDC may be of medical interest since it was able to inhibit platelet aggregation.
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Simulation analysis of cascade controller for DC-DC bank converter
International Nuclear Information System (INIS)
Mahar, M.A.; Abro, M.R.; Larik, A.S.
2009-01-01
Power electronic converters are periodic variable structure systems due to their switched operation. During the last few decades several new dc-dc converter topologies have emerged. Buck converter being simple in topology, has recently drawn attraction of many researchers. Basically, a buck converter is highly underdamped system. In order to overcome the developed oscillations in output of this converter, various control techniques have been proposed. However, these techniques are fraught with many drawbacks. This paper focus on a cascade controller based buck topology. Steady state analysis is given in this paper which shows output voltage and inductor current in detail. Dynamic analysis for line and load variation is also presented. The buck topology is implemented and simulated in MATLAB/Simulink. The simulated results are presented. (author)
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Bidirectional dc-to-dc Power Converter
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.
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Pulsed dc self-sustained magnetron sputtering
International Nuclear Information System (INIS)
Wiatrowski, A.; Posadowski, W. M.; Radzimski, Z. J.
2008-01-01
The magnetron sputtering has become one of the commonly used techniques for industrial deposition of thin films and coatings due to its simplicity and reliability. At standard magnetron sputtering conditions (argon pressure of ∼0.5 Pa) inert gas particles (necessary to sustain discharge) are often entrapped in the deposited films. Inert gas contamination can be eliminated during the self-sustained magnetron sputtering (SSS) process, where the presence of the inert gas is not a necessary requirement. Moreover the SSS process that is possible due to the high degree of ionization of the sputtered material also gives a unique condition during the transport of sputtered particles to the substrate. So far it has been shown that the self-sustained mode of magnetron operation can be obtained using dc powering (dc-SSS) only. The main disadvantage of the dc-SSS process is its instability related to random arc formation. In such case the discharge has to be temporarily extinguished to prevent damaging both the magnetron source and power supply. The authors postulate that pulsed powering could protect the SSS process against arcs, similarly to reactive pulsed magnetron deposition processes of insulating thin films. To put this concept into practice, (i) the high enough plasma density has to be achieved and (ii) the type of pulsed powering has to be chosen taking plasma dynamics into account. In this article results of pulsed dc self-sustained magnetron sputtering (pulsed dc-SSS) are presented. The planar magnetron equipped with a 50 mm diameter and 6 mm thick copper target was used during the experiments. The maximum target power was about 11 kW, which corresponded to the target power density of ∼560 W/cm 2 . The magnetron operation was investigated as a function of pulse frequency (20-100 kHz) and pulse duty factor (50%-90%). The discharge (argon) extinction pressure level was determined for these conditions. The plasma emission spectra (400-410 nm range) and deposition
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Troubleshooting of Modulator DC power supply at KOMAC
Energy Technology Data Exchange (ETDEWEB)
Jeong, Hae Seong; Kim, Han Sung; Kwon, Hyeok Jung; Kim, Seong Gu; Kim, Dae Il; Lee, Seok Geun; Kim, Jae Ha; Seol, Kyeong Tae; Cho, Yong Sub [KAERI, Daejeon (Korea, Republic of)
2016-05-15
The process of solving problems to operate the 2nd converter modulator will be introduced. Also, the PSpice simulation result about the 12-pulse rectifier will be compared with the measurement result. KOMAC (KOrea Multi-purpose Accelerator Complex) has four HVCMs (High Voltage Converter Modulator) which are the power source of nine klystrons. Four HVCMs are already operated since 2013 for operating the 100 MeV linear proton accelerator at KOMAC. This HVCM system includes the 12-pulse rectifier (ac-dc), capacitors bank (dc-link, Pos, Neg) and converter modulator (dc-dc). Especially, the 12-pulse rectifier system receives the power from the utility and converts 3,300 ac voltage to 2,200 dc voltage for supplying the dc power to the capacitors bank. This rectifier system used twelve thyristors for the rectification and applied RC snubber networks to protect the semiconductor switches (thyristors). Since the 2nd modulator dc power supply has troubled, the troubleshooting process conducted by the staves of KOMAC. It takes 3 months to solve the problems because it is not easy to find the faulty wiring. Nevertheless, our staves found the faulty point with a hope to operate the modulator system and the PSpice simulation helps to solve the problems. Using PSpice which is tool for simulating the circuit, the dc power supply abnormal phenomenon was simulated exactly. After corrected the faulty wiring, the modulator dc power supply operated.
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Simberg, Maximilian
2014-01-01
Det här arbetet behandlar kreativ frihet och konstnärligt oberoende i filmskapande, utgående från begreppet independent film och regissörerna David Lynch, Jim Jarmusch och Steven Soderbergh. Den centrala frågeställningen är hur det har varit möjligt för en filmkonstnär att uppnå konstnärligt oberoende och samtidigt ha en långlivad och framgångsrik karriär. Arbetets fokus ligger på de tre regissörernas genombrottsfilmer; Eraserhead, Stranger Than Paradise och sex, lies, and videotape, och förs...
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2008-01-01
Küsimusele vastavad hariduskolleegiumi algkooli 3. klassi õpilane Egert, prantsuse lütseumi 12. klassi õpilane Triinu Lepp, Sillamäe kutsekooli 3. kursuse õpilane Gleb Tšurbanov, Tallinna reaalkooli 11. klassi õpilane Erik Paemurru, Toronto Crescenti keskkooli õpilane Steven Huang, kunstiakadeemia muinsuskaitse- ja restaureerimisosakonna õppejõud Jaan Tamm, Tartu Miina Härma gümnaasiumi 2. a klassi õpilane Erki Külaots, Tallinna 21. kooli 11. klassi õpilane Sander Kaur ja Tapa gümnaasiumi 7. klassi õpilane Evelin Orgse
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Peppercorn, Amanda F.; Miller, Melissa B.; Fitzgerald, David; Weber, David J.; Groben, Pamela A.; Cairns, Bruce A.
2015-01-01
The pathogenesis of Stevens Johnson Syndrome (SJS) remains obscure but it has been associated with various infectious agents, including members of the Herpes virus family. We present the first report of high level human herpesvirus-6 (HHV-6) viremia at the onset of SJS suggesting a possible new association. This finding supports the need for further investigation into the possible relationship between HHV-6 and SJS which may illuminate the pathogenesis of SJS and bring us closer to achieving enhanced prevention and treatment of this rare disease. PMID:20182379
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Geometry Optimization of DC/RF Photoelectron Gun
Chen Ping; Yu, David
2005-01-01
Pre-acceleration of photoelectrons in a pulsed, high voltage, short, dc gap and its subsequent injection into an rf gun is a promising method to improve electron beam emittance in rf accelerators. Simulation work has been performed in order to optimize the geometric shapes of a dc/rf gun and improve electron beam properties. Variations were made on cathode and anode shapes, dc gap distance, and inlet shape of the rf cavity. Simulations showed that significant improvement on the normalized emittance (< 1 mm-mrad), compared to a dc gun with flat cathode, could be obtained after the geometric shapes of the gun were optimized.
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Modeling, Control and Protection of Low-Voltage DC Microgrids
Salomonsson, Daniel
2008-01-01
Current trends in electric power consumption indicate an increasing use of dc in end-user equipment, such as computers and other electronic appliances used in households and offices. With a dc power system, ac/dc conversion within these loads can be avoided, and losses reduced. AC/DC conversion is instead centralized, and by using efficient, fully controllable power-electronic interfaces, high power quality for both ac and dc systems during steady state and ac grid disturbances can be obtaine...
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DEFF Research Database (Denmark)
Liu, Dong; Deng, Fujin; Chen, Zhe
2017-01-01
The capacitor current would be imbalanced under the conventional control strategy in the half-bridge three-level (HBTL) DC/DC converter due to the effect of the output inductance of the power supply and the input line inductance, which would affect the converter's reliability. This paper proposes...... a pulse-wide modulation (PWM) strategy composed of two operation modes for the HBTL DC/DC converter, which can realize the zero-voltage switching (ZVS) for the efficiency improvement. In addition, a capacitor current balancing control is proposed by alternating the two operation modes of the proposed ZVS...... PWM strategy, which can eliminate the current imbalance among the two input capacitors. Therefore, the proposed control strategy can improve the converter's performance and reliability in: 1) reducing the switching losses and noises of the power switches; 2) balancing the thermal stresses...
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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...
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2010-06-23
... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, and MD-10-10F Airplanes... certain McDonnell Douglas Model DC-10-10, DC-10-10F, and MD-10-10F airplanes. That NPRM was published in... amends Sec. 39.13 by adding the following new AD: 2010-13-06 McDonnell Douglas Corporation: Amendment 39...
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Active superconducting DC fault current limiter based on flux compensation
International Nuclear Information System (INIS)
Shi Jing; Tang Yuejin; Wang, Chen; Zhou Yusheng; Li Jingdong; Ren Li; Chen Shijie
2006-01-01
With the extensive application of DC power systems, suppression of DC fault current is an important subject that guarantees system security. This paper presents an active superconducting DC fault current limiter (DC-SFCL) based on flux compensation. The DC-SFCL is composed of two superconducting windings wound on a single iron core, the primary winding is in series with DC power system, and the second winding is connected with AC power system through a PWM converter. In normal operating state, the flux in the iron core is compensated to zero, and the SFCL has no influence on DC power system. In the case of DC system accident, through regulating the active power exchange between the SFCL's second winding and the AC power system, the current on the DC side can be limited to different level complying with the system demand. Moreover, the PWM converter that interface the DC system and AC system can be controlled as a reactive power source to supply voltage support for the AC side, which has little influence on the performance of SFCL. Using MATLAB SIMULINK, the mathematic model of the DC-SFCL is created, simulation results validate the dynamics of system, and the performance of DC-SFCL is confirmed
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DEFF Research Database (Denmark)
Wang, Haojie; Han, Minxiao; Han, Renke
2018-01-01
This paper proposes a decentralized current-sharing control strategy to endow fast transient response to paralleled DC-DC converters systems, such as DC microgrids or distributed power systems. The proposed controller consist of two main control loops: an external voltage droop control for current......-sharing proposes and an internal current loop. The external droop control loop is designed as a voltage loop with embedded virtual impedance, which avoids the use of a slow voltage loop and a separate extra virtual impedance loop that may limit the system bandwidth. The internal current loop, thanks...... and the proposed embedded-virtual-impedance based I-V droop. In order to compare the dynamic response performances between two droop controllers, their state-space models have been developed and analyzed in this paper. The results show that the dynamic response of the I-V droop control is faster than...
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A Reconfigurable Series Resonant DC-DC Converter for Wide-Input and Wide-Output Voltages
DEFF Research Database (Denmark)
Shen, Yanfeng; Wang, Huai; Qin, Zian
2017-01-01
This paper proposes a dual-bridge based LC series resonant dc-dc converter. The input inverter unit incorporates two bridge structures, i.e., a full-bridge inverter and a half-bridge inverter. For the output rectifier, it can be a full-bridge rectifier or an asymmetric half-bridge rectifier....... Different from the conventional resonant converter, a fixed-frequency PWM control is employed which makes the optimization of magnetic components easier. The primary-side switches can achieve ZVS and the secondary-side diodes turn off with ZCS. In addition, the root-mean-square (RMS) values...... of the transformer currents do not significantly vary with respect to the voltage variation. Therefore, this converter can maintain high efficiency over a wide voltage range. The topology and operating principle are firstly described. Then the dc voltage gain and the RMS current characteristics are detailed. Finally...
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International Nuclear Information System (INIS)
Musio, D.; Parisi, E.; Dionisi, F.
2009-01-01
Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are two of the most severe, rare, and life-threatening adverse reactions to medications. Their incidence is approximately two patients per million population per year. Several cases have been reported in the literature in which SJS and TEN have occurred in patients with a neoplasm undergoing radiation therapy and who are taking an anticonvulsant. We report a case of SJS-TEN that developed in a 51-year-old woman with nonresectable non-small-cell lung cancer during treatment with phenobarbital plus radiation therapy for bone metastases but in whom the irradiated areas did not exhibit the SJS skin reaction. To our knowledge, no similar cases have been reported in the literature. (author)
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International Nuclear Information System (INIS)
Silva-Ortigoza, R; Marciano-Melchor, M; Silva-Ortigoza, G; Hernández-Guzmán, V M; Saldaña-González, G; Marcelino-Aranda, M
2012-01-01
We introduce a dc/dc boost power converter as a didactic prototype intended to support courses on electric circuit analysis experimentally. The corresponding mathematical model is obtained, the converter is designed and an experimental setup is described, constructed and tested. Simplicity of construction as well as low cost of components renders the feasible introduction of this equipment in undergraduate laboratories. (paper)
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Security analysis of interconnected AC/DC systems
DEFF Research Database (Denmark)
Eriksson, Robert
2015-01-01
This paper analyses N-1 security in an interconnected ac/dc transmission system using power transfer distribution factors (PTDFs). In the case of a dc converter outage the power needs to be redistributed among the remaining converter to maintain power balance and operation of the dc grid...... any line or transformer limits. Simulations were performed in a model of the Nordic power system where a dc grid is placed on top. The simulation supports the method as a tool to consider transfer limits in the grid to avoid violate the same and increase the security after a converter outage........ The redistribution of power has a sudden effect on the power-flow in the interconnected ac system. This may cause overloading of lines and transformers resulting in disconnection of equipment, and as a consequence cascading failure. The PTDF is used as a method to analyze and avoid violating limits by in the dc...
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Systematic design approach of fuzzy PID stabilizer for DC-DC converters
International Nuclear Information System (INIS)
Guesmi, K.; Essounbouli, N.; Hamzaoui, A.
2008-01-01
DC-DC converters process electrical energy by switching between a fixed number of configurations. The objective of controlling these systems is to provide better performances, ensure closed loop stability and guarantee a simple predictable behaviour. Based on a converter averaged model, we propose, in this paper, a systematic design approach of a fuzzy PID. The choice of controller parameters stands on the whole system stability requirements. Extension of the obtained asymptotic stability to structural stability is presented to show that the developed controller ensures also a simple and predictable behaviour of the converter. Finally, we illustrate the efficiency of the proposed fuzzy PID design approach through simulations in voltage mode as well as in current mode control
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Systematic design approach of fuzzy PID stabilizer for DC-DC converters
Energy Technology Data Exchange (ETDEWEB)
Guesmi, K.; Essounbouli, N.; Hamzaoui, A. [CReSTIC, IUT de Troyes 09, rue de Quebec BP. 396, 10026 Troyes (France)
2008-10-15
DC-DC converters process electrical energy by switching between a fixed number of configurations. The objective of controlling these systems is to provide better performances, ensure closed loop stability and guarantee a simple predictable behaviour. Based on a converter averaged model, we propose, in this paper, a systematic design approach of a fuzzy PID. The choice of controller parameters stands on the whole system stability requirements. Extension of the obtained asymptotic stability to structural stability is presented to show that the developed controller ensures also a simple and predictable behaviour of the converter. Finally, we illustrate the efficiency of the proposed fuzzy PID design approach through simulations in voltage mode as well as in current mode control. (author)
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Deadbeat control of power leveling unit with bidirectional buck/boost DC/DC converter
Hamasaki, Shin-ichi; Mukai, Ryosuke; Yano, Yoshihiro; Tsuji, Mineo
2014-01-01
As a distributed generation system increases, a stable power supply becomes difficult. Thus control of power leveling (PL) unit is required to maintain the balance of power flow for irregular power generation. The unit is required to respond to change of voltage and bidirectional power flow. So the bidirectional buck/boost DC/DC converter is applied for the control of PL unit in this research. The PL unit with Electric double-layer capacitor (EDLC) is able to absorb change of power, and it is...
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Directory of Open Access Journals (Sweden)
Li Zhai
2018-04-01
Full Text Available The high dv/dt and di/dt outputs from power devices in a high-low voltage DC-DC converter on electric vehicles (EVs can always introduce the unwanted conducted electromagnetic interference (EMI emissions. A conducted EMI prediction and mitigation strategy that is based on transfer function for the high-low voltage DC-DC converter in EVs are proposed. A complete test for the DC-DC converter is conducted to obtain the conducted EMI from DC power cables in the frequency band of 150 kHz-108 MHz. The equivalent circuit with high-frequency parasitic parameters of the DC-DC converter is built`1 based on the measurement results to acquire the characteristics of the conducted EMI of the DC power cables. The common mode (CM and differential mode (DM propagation coupling paths are determined, and the corresponding transfer functions of the DM interference and CM interference are established. The simulation results of the conducted EMI can be obtained by software Matlab and Computer Simulation Technology (CST. By analyzing the transfer functions and the simulation results, the dominated interference is the CM interference, which is the main factor of the conducted EMI. A mitigation strategy for the design of the CM interference filter based on the dominated CM interference is proposed. Finally, the mitigation strategy of the conducted EMI is verified by performing the conducted voltage experiment. From the experiment results, the conducted voltage of the DC power cables is decreased, respectively, by 58 dBμV, 55 dBμV, 65 dBμV, 53 dBμV, and 54 dBμV at frequency 200 kHz, 400 kHz, 600 kHz, 1.4 MHz, and 50 MHz. The conduced voltage in the frequency band of 150 kHz–108 MHz can be mitigated by adding the CM interference filters, and the values are lower than the limit level-3 of CISPR25 standard (GB/T 18655-2010.
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DEFF Research Database (Denmark)
Pelan, Ovidiu; Cornea, Octavian; Muntean, Nicolae
2014-01-01
This paper presents and discusses design considerations and efficiency investigation of a conventional step-down and a hybrid switched-capacitor DC-DC converter. Three MOSFETs with low on-resistance have been tested for each converter in order to find the most adequate switch for this application....... The experimental results and comparative efficiency graphs were obtained with a 1kW laboratory prototype dedicated for a 42/14V dual voltage automotive system....
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MEDOW - Multi-terminal DC Grid for Offshore Wind, Final report
DEFF Research Database (Denmark)
A DC grid based on multi-terminal voltage-source converter is a newly emerging technology, which is particularly suitable for the connection of offshore wind farms. Multi-terminal DC grids will be the key technology for the European offshore ‘Super Grid’. In the project, DC power flow, DC relaying...... protection, steady state operation, dynamic stability, fault-ride through capability, and impacts of DC grids on the operation of AC grids and power market were studied. Systematic comparison of DC grid topologies and stability control strategies was carried out, and DC grids for offshore wind power...
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Kingsnorth-London dc transmission link
Energy Technology Data Exchange (ETDEWEB)
1966-03-11
The hvdc transmission link between one of the 500 MW generators at Kingsnorth Power Station and two receiving stations in London will use a three-wire dc cable system rated to carry 1200 A at +- 266 kV. This 51-mile system will be the first dc link in the world to be used as an integral part of a complex interconnected ac network.
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Dual wound dc brush motor gearhead
Henson, Barrie W.
1986-01-01
The design requirements, the design, development tests and problems, the qualification and life test and the findings of the strip examination of a dual wound DC brushed motor gearhead are described. It is the only space qualified dual wound dc brushed motor gearhead in Europe.
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Analysis and Controller Design of a Universal Bidirectional DC-DC Converter
Directory of Open Access Journals (Sweden)
Kou-Bin Liu
2016-06-01
Full Text Available In this paper, first the operating principles of a non-isolated universal bidirectional DC-DC converter are studied and analyzed. The presented power converter is capable of operating in all power transferring directions in buck/boost modes. Zero voltage switching can be achieved for all the power switches through proper modulation strategy design, therefore, the presented converter can achieve high efficiency. To further improve the efficiency, the relationship between the phase-shift angle and the overall system efficiency is analyzed in detail, an adaptive phase-shift (APS control method which determines the phase-shift value between gating signals according to the load level is then proposed. As the modulation strategy is a software-based solution, there is no requirement for additional circuits, therefore, it can be implemented easily and instability and noise susceptibility problems can be reduced. To validate the correctness and the effectiveness of the proposed method, a 300 W prototyping circuit is implemented and tested. A low cost dsPIC33FJ16GS502 digital signal controller is adopted in this paper to realize the power flow control, DC-bus voltage regulation and APS control. According to the experimental results, a 12.2% efficiency improvement at light load and 4.0% efficiency improvement at half load can be achieved.
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Drilling history core hole DC-6 Hanford, Washington
International Nuclear Information System (INIS)
1978-06-01
Core hole DC-6 was completed in May 1978 by Boyles Brothers Drilling Company, Spokane, Washington, under subcontract to Fenix and Scisson, Inc. The hole was cored for the US Department of Energy and the Rockwell Hanford Operations' Basalt Waste Isolation Program. Fenix and Scisson, Inc. furnished the engineering, daily supervision of the core drilling activities, and geologic core logging for hole DC-6. Core hole DC-6 is located within the boundary of the Hanford Site at the old Hanford town site. The Hanford Site coordinates for DC-6 are North 54,127.17 feet and West 17,721.00 feet. The surface elevation is approximately 402 feet above sea level. The purpose of core hole DC-6 was to core drill vertically through the basalt and interbed units for stratigraphic depth determination and core collection and to provide a borehole for hydrologic testing. The total depth of core hole DC-6 was 4336 feet. Core recovery was 98.4% of the total footage cored
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Iyer, Geetha; Srinivasan, Bhaskar; Agarwal, Shweta; Kamala Muralidharan, Seema; Arumugam, Sumathi
2014-03-01
Stevens Johnson Syndrome (SJS) can lead to end stage corneal blindness. This study describes the comprehensive treatment measures and their outcomes in the management of ocular sequelae and complications of SJS. Four hundred sixty-four eyes of 232 patients of SJS who underwent surgical intervention (punctal cautery, mucus membrane grafting for lid margin keratinisation, fornix reconstructive procedures, tectonic procedures, keratoplasty and keratoprosthesis) were studied. It was a non-comparative, retrospective, interventional case series. The primary outcome was the change in the best corrected visual acuity (BCVA). Secondary outcome measures included an improvement in the ocular surface status as indicated by corneal epithelial fluorescein staining and Schirmer's I strip wetting. The BCVA and the ocular surface status improved and/or stabilized in > 70 % of eyes following punctal cautery (n = 160) and > 80 % of eyes following lid margin mucus membrane grafting (n = 238). BCVA improved in 50 % of eyes following fornix reconstructive procedures (n = 24) with COMET (n = 6), in 63.9 % eyes with the Prosthetic Replacement of the Ocular Surface Ecosystem (PROSE) lens (n = 36), in 81.8 % of eyes after cataract surgery (n = 22). A BCVA of ≥20/200 was achieved in 72.34 % of eyes following keratoprostheses procedures (n = 47). The mean duration of follow up was 53.3 ± 15.2 months. The ocular sequelae of Stevens Johnson Syndrome can be blinding. They need to be identified and addressed early to retard the continued deterioration of the ocular surface. Our study aims to highlight the problem as well as the importance of comprehensive measures in the management of this potentially blinding disorder.
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Bae, Hyun Min; Park, Yoo Jung; Kim, Young Hoon; Moon, Dong Eon
2013-01-01
Stevens-Johnson syndrome (SJS) is a rare but life-threatening skin reaction disease and carbamazepine is one of its most common causes. We report a case of SJS secondary to carbamazepine in a patient with previous pruritus due to carbamazepine which was given for treatment of trigeminal neuralgia. We would like to caution all providers that carbamazepine readministration should be avoided in the patient with a previous history of SJS or adverse skin reaction. In addition, we strongly recommen...
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Spinu, V.; Oliveri, A.; Lazar, M.; Storace, M.
2012-01-01
This paper proposes a method for FPGA implementation of explicit, piecewise af¿ne (PWA) model predictive control (MPC) laws for non-inverting buck-boost DC-DC converters. A novel approach to obtain a PWA model of the power converter is proposed and two explicit MPC laws are derived, i.e., one based
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DEFF Research Database (Denmark)
Török, Lajos; Mathe, L.
2017-01-01
The purpose of this work was to investigate effect of the DC-link voltage feed-forward compensation on the stability of the three-phase-grid connected DC power supply, used for electrolysis application, equipped with small DC link capacitor. In case of weak grid condition, the system...
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Directory of Open Access Journals (Sweden)
Moh. Zaenal Efendi
2013-12-01
Full Text Available This paper presents a design and implementation of a converter which has a high power factor for battery charger application. The converter is a combination of a SEPIC converter and a full-bridge DC-DC converter connected in two stages of series circuit. The SEPIC converter works in discontinuous conduction mode and it serves as a power factor corrector so that the shape of input current waveform follows the shape of input voltage waveform. The full-bridge DC-DC converter serves as a regulator of output voltage and operates at continuous conduction mode. The experimental results show that the power factor of this converter system can be achieved up to 0.96.
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Modified High Voltage Conversion Inverting Cuk DC-DC Converter for Renewable Energy Application
DEFF Research Database (Denmark)
Maroti, Pandav Kiran; Padmanaban, Sanjeevikumar; Wheeler, Patrick
2017-01-01
controlled device DC-DC topology. The voltage conversion ratio of proposed converter has increased by ten times of the conventional Cuk converterat a duty ratio of 90%. The detailed analysis of the voltage conversion ratio and losses occur due to internal resistance of components is done in the paper......The proposed exertion represents the modified high voltage conversion Cuk converter for renewable energy application. The proposed Cuk converter is a combination of the conventional boost converter and Cuk converter. The arrangement of the proposed converter make, such as, it becomes the single...
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International Nuclear Information System (INIS)
Delattre, J.Y.; Safai, B.; Posner, J.B.
1988-01-01
In 15 months we encountered eight patients with intracranial tumors who developed erythema multiforme (EM) or erythema multiforme bullosa (Stevens-Johnson syndrome). All occurred shortly after use of phenytoin (DPH) and brain radiation therapy (WBRT). The clinical picture differed from the classic form of EM in that the erythema began on the scalp and spread to the extremities, progressing in three cases to extensive bullous formation. There were no cases of EM among patients who received either DPH or radiotherapy alone. The combination of DPH, WBRT, and tapering of steroids seems to predispose to EM. The pathogenesis of the disorder is probably immunologic. In the absence of seizures, anticonvulsants should not be given routinely to patients with brain tumors. When anticonvulsants are necessary in patients scheduled for WBRT, DPH may not be the drug of choice
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Graham, Christopher F; Solter, Davor; Gearhart, John D; Nadeau, Joseph H; Knowles, Barbara B
2016-01-01
In 2016, a symposium was convened in Leroy C. Stevens' honor, in association with a meeting of the International Stem Cell Initiative (ISCI). ISCI, funded internationally, is composed of a group of ~100 scientists from many countries, under the leadership of Peter Andrews, who have worked together to characterize a significant number of human pluripotent stem cell lines, to monitor their genetic stability and their differentiation into mature cell types and tissues in vitro and in vivo. Those at the ISCI meeting puzzled through one of the thorniest problems in the therapeutic use of the differentiated derivatives of pluripotent stem cells for human therapy; namely, pluripotent stem cells can differentiate into any cell type in the adult organism, but they also have the capacity for unlimited self-renewal, hence if mutated they may have tumorigenic potential. The meeting considered how these cells might become genetically or epigenetically abnormal and how the safety of these cells for human therapeutic uses could be assessed and assured. The symposium was an opportunity to pay tribute to Leroy Stevens and to the basic science origins of this newest aspect of regenerative medicine. It was a time to reflect on the past and on how it can influence the future of our field.
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National Aeronautics and Space Administration — The goal of the project was to demonstrate a true direct current (DC) transformer, a new electro-mechanical component with potentially high power applications; in...
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Unregulated Series Resonant Converter for Interlinking DC Nanogrids
DEFF Research Database (Denmark)
Tomas Manez, Kevin; Zhang, Zhe; Ouyang, Ziwei
2017-01-01
bidirectional converter to interlink a 400V DC bus with a 48V DC bus ispresented. The proposed converter is based on a LLC resonant converter operating as a DC transformer at a fixed frequency and duty cycle without any complex control strategy. A clearand simplified design procedure for high efficiency...
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Bicycles, Airplanes and Peter Pans: Flying Scenes in Steven Spielberg's Films
Directory of Open Access Journals (Sweden)
Emilio Audissino
2014-10-01
Full Text Available In Steven Spielberg's cinema the flight is a recurring theme. Flying scenes can be sorted into two classes: those involving a realistic flight – by aircraft – and those involving a magical flight – by supernatural powers. The realistic flight is influenced by the war stories of Spielberg's father – a radio man in U.S. Air-force during WWII – and it is featured in such films as Empire of the Sun (1987, Always (1989, and 1941 (1979. The magical flight is influenced by James M. Barries' character Peter Pan (Peter and Wendy, 1911, which is quoted directly in E.T. the Extraterrestrial (1982 and, above all, in Hook (1991, which is a sequel to Barrie's story. These two types of flying scenes are analysed as to their meanings, compared to the models that influenced them, and surveyed as to their evolution across Spielberg's films. A central case study is the episode The Mission from Amazing Stories (1985, in which the realistic and the magical flights overlap.
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Shimer, Daniel W.; Lange, Arnold C.
1995-01-01
A high-power power supply produces a controllable, constant high voltage output under varying and arcing loads. The power supply includes a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current. The power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle and circuitry is provided for sensing incipient arc currents at the output of the power supply to simultaneously decouple the power supply circuitry from the arcing load. The power supply includes a plurality of discrete switching type dc--dc converter modules.
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Shimer, D.W.; Lange, A.C.
1995-05-23
A high-power power supply produces a controllable, constant high voltage output under varying and arcing loads. The power supply includes a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current. The power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle and circuitry is provided for sensing incipient arc currents at the output of the power supply to simultaneously decouple the power supply circuitry from the arcing load. The power supply includes a plurality of discrete switching type dc--dc converter modules. 5 Figs.
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DC-DC Converter Topology Assessment for Large Scale Distributed Photovoltaic Plant Architectures
Energy Technology Data Exchange (ETDEWEB)
Agamy, Mohammed S; Harfman-Todorovic, Maja; Elasser, Ahmed; Sabate, Juan A; Steigerwald, Robert L; Jiang, Yan; Essakiappan, Somasundaram
2011-07-01
Distributed photovoltaic (PV) plant architectures are emerging as a replacement for the classical central inverter based systems. However, power converters of smaller ratings may have a negative impact on system efficiency, reliability and cost. Therefore, it is necessary to design converters with very high efficiency and simpler topologies in order not to offset the benefits gained by using distributed PV systems. In this paper an evaluation of the selection criteria for dc-dc converters for distributed PV systems is performed; this evaluation includes efficiency, simplicity of design, reliability and cost. Based on this evaluation, recommendations can be made as to which class of converters is best fit for this application.
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SSP Technology Investigation of a High-Voltage DC-DC Converter
Pappas, J. A.; Grady, W. M.; George, Patrick J. (Technical Monitor)
2002-01-01
The goal of this project was to establish the feasibility of a high-voltage DC-DC converter based on a rod-array triggered vacuum switch (RATVS) for the Space Solar Power system. The RATVS has many advantages over silicon and silicon-carbide devices. The RATVS is attractive for this application because it is a high-voltage device that has already been demonstrated at currents in excess of the requirement for an SSP device and at much higher per-device voltages than existing or near-term solid state switching devices. The RATVS packs a much higher specific power rating than any solid-state device and it is likely to be more tolerant of its surroundings in space. In addition, pursuit of an RATVS-based system would provide NASA with a nearer-term and less expensive power converter option for the SSP.
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Kaczmarek, Dominik; Jankowska, Elzbieta
2018-03-15
Direct current (DC) evokes long-lasting changes in neuronal networks both presynaptically and postsynaptically and different mechanisms were proposed to be involved in them. Different mechanisms were also suggested to account for the different dynamics of presynaptic DC actions on myelinated nerve fibers stimulated before they entered the spinal gray matter and on their terminal branches. The aim of the present study was to examine whether these different dynamics might be related to differences in the involvement of K + channels. To this end, we compared effects of the K + channel blocker 4-amino-pyridine (4-AP) on DC-evoked changes in the excitability of afferent fibers stimulated within the dorsal columns (epidurally) and within their projection areas in the dorsal horn and motor nuclei (intraspinally). 4-AP was applied systemically in deeply anesthetized rats. DC-evoked increases in the excitability of epidurally stimulated afferent nerve fibers, and increases in field potentials evoked by these fibers, were not affected by 4-AP. In contrast, sustained decreases rather than increases in the excitability of intraspinally stimulated terminal nerve branches were evoked by local application of DC in conjunction with 4-AP. The study leads to the conclusion that 4-AP-sensitive K + channels contribute to the sustained DC-evoked post-polarization increases in the excitability at the level of terminal branches of nerve fibers but not of the nodes of Ranvier nor within the juxta-paranodal regions where other mechanisms would be involved in inducing the sustained DC-evoked changes. Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.
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Predictive Trailing-Edge Modulation Average Current Control in DC-DC Converters
Directory of Open Access Journals (Sweden)
LASCU, D.
2013-11-01
Full Text Available The paper investigates predictive digital average current control (PDACC in dc/dc converters using trailing-edge modulation (TEM. The study is focused on the recurrence duty cycle equation and then stability analysis is performed. It is demonstrated that average current control using trailing-edge modulation is stable on the whole range of the duty cycle and thus design problems are highly reduced. The analysis is carried out in a general manner, independent of converter topology and therefore the results can then be easily applied for a certain converter (buck, boost, buck-boost, etc.. The theoretical considerations are confirmed for a boost converter first using the MATLAB program based on state-space equations and finally with the CASPOC circuit simulation package.
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Control of hybrid AC/DC microgrid under islanding operational conditions
DEFF Research Database (Denmark)
Ding, G.; Gao, F.; Zhang, S.
2014-01-01
This paper presents control methods for hybrid AC/DC microgrid under islanding operation condition. The control schemes for AC sub-microgrid and DC sub-microgrid are investigated according to the power sharing requirement and operational reliability. In addition, the key control schemes...... of interlinking converter with DC-link capacitor or energy storage, which will devote to the proper power sharing between AC and DC sub-microgrids to maintain AC and DC side voltage stable, is reviewed. Combining the specific control methods developed for AC and DC sub-microgrids with interlinking converter......, the whole hybrid AC/DC microgrid can manage the power flow transferred between sub-microgrids for improving on the operational quality and efficiency....
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Schneider, Jeremy A.; Cohen, Philip R.
2017-01-01
Introduction Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are two of the most severe dermatologic conditions occurring in the inpatient setting. There is a lack of consensus regarding appropriate management of SJS and TEN. Purpose The scientific literature pertaining to SJS and TEN (subsequently referred to as SJS/TEN) is summarized and assessed. In addition, an interventional approach for the clinician is provided. Methods PubMed was searched with the key words: cortic...
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A Quantitative Electrochemiluminescence Assay for Clostridium perfringens alpha toxin
2006-08-10
Doyle, L.R. Beuchat, T.J. Montville (Eds.), Food Microbiology : Fundamentals and Fron- tiers, Second ed., ASM Press, Washington, D.C., 2001, pp. 351...D.E. Lorant, A.E. Bryant, G.A. Zimmerman, T.M. McIn- tyre, D.L. Stevens, S.M. Prescott , Alpha toxin from Clostridium per- fringens induces
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Sitompul, Fuad Rahim
2015-01-01
Motor listrik merupakan perangkat elekromagnetis yang mengubah energi listrik menjadi energi mekanik. Motor DC memerlukan tegangan searah pada kumparan medan untuk diubah menjadi energi mekanik. Energi mekanik ini digunakan sebagai penggerak peralatan listrik seperti pompa,penggerak kipas angin, lift dan lain-lain. Karena penggunaannya yang cukup luas maka kinerjanya harus baik. Kinerja suatu motor DC dikatakan baik jika efisiensi motor tersebut tinggi. Hal itu dapat dicapai dengan mengatur b...
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A soft-switching coupled inductor bidirectional DC-DC converter with high-conversion ratio
Chao, Kuei-Hsiang; Jheng, Yi-Cing
2018-01-01
A soft-switching bidirectional DC-DC converter is presented herein as a way to improve the conversion efficiency of a photovoltaic (PV) system. Adoption of coupled inductors enables the presented converter not only to provide a high-conversion ratio but also to suppress the transient surge voltage via the release of the energy stored in leakage flux of the coupled inductors, and the cost can kept down consequently. A combined use of a switching mechanism and an auxiliary resonant branch enables the converter to successfully perform zero-voltage switching operations on the main switches and improves the efficiency accordingly. It was testified by experiments that our proposed converter works relatively efficiently in full-load working range. Additionally, the framework of the converter intended for testifying has high-conversion ratio. The results of a test, where a generating system using PV module array coupled with batteries as energy storage device was used as the low-voltage input side, and DC link was used as high-voltage side, demonstrated our proposed converter framework with high-conversion ratio on both high-voltage and low-voltage sides.
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Solar Photovoltaic DC Systems: Basics and Safety: Preprint
Energy Technology Data Exchange (ETDEWEB)
McNutt, Peter F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sekulic, William R [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dreifuerst, Gary [Lawrence Livermore National Laboratory - retired
2018-04-02
Solar Photovoltaic (PV) systems are common and growing with 42.4 GW installed capacity in U.S. (almost 15 GW added in 2016). This paper will help electrical workers, and emergency responders understand the basic operating principles and hazards of PV DC arrays. We briefly discuss the following aspects of solar photovoltaic (PV) DC systems: the effects of solar radiation and temperature on output power; PV module testing standards; common system configurations; a simple PV array sizing example; NEC guidelines and other safety features; DC array commissioning, periodic maintenance and testing; arc-flash hazard potential; how electrical workers and emergency responders can and do work safely around PV arrays; do moonlight and artificial lighting pose a real danger; typical safe operating procedures; and other potential DC-system hazards to be aware of. We also present some statistics on PV DC array electrical incidents and injuries. Safe PV array operation is possible with a good understanding of PV DC arrays basics and having good safe operating procedures in place.
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Digital DC beam current measurement on SSRF storage ring
International Nuclear Information System (INIS)
Xiong Liang; Yin Chongxian; Liu Ming; Chen Jianfeng
2011-01-01
Both DC current transformer (DCCT) and integrating current transformer (ICT) can be used in DC beam current measurement. The ICT has strong capability of resisting electromagnetic interference, but its measurement accuracy cannot satisfy the DC beam current measurement requirement when using traditional high speed A/D. With high resolution A/D and equivalent sampling system, DC beam current measuring system based on ICT can reach high accuracy compared with DCCT system. In this paper, the ICT-based DC beam current measurement, equivalent sampling method and testing results at Shanghai Synchrotron Radiation Facility(SSRF) is described. (authors)
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Nash, Aaron; Soheili, Arash; Tambar, Uttam K
2013-09-20
Unnatural cyclic amino acids are valuable tools in biomedical research and drug discovery. A two-step stereoselective strategy for converting simple glycine-derived aminoesters into unnatural cyclic amino acid derivatives has been developed. The process includes a palladium-catalyzed tandem allylic amination/[2,3]-Stevens rearrangement followed by a ruthenium-catalyzed ring-closing metathesis. The [2,3]-rearrangement proceeds with high diastereoselectivity through an exo transition state. Oppolzer's chiral auxiliary was utilized to access an enantiopure cyclic amino acid by this approach, which will enable future biological applications.
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Method to predetermine current/power flow change in a dc grid
DEFF Research Database (Denmark)
2017-01-01
occurs at one of the AC/DC converters; establishing a generalized droop feedback gain matrix G; controlling current/power flow within DC grid towards predefined setpoints, by use of control law. The invention presents an analytical approach to derive the generalized feedback gain allowing......The invention relates to a method for controlling current/power flow within a power transmission system, comprising two or more interconnected converter stations. The method comprises the steps of: providing a DC admittance matrix given from the DC grid; providing a current distribution matrix...... for a number of, such as for all possible AC/DC converter outages; providing a DC bus voltage vector for the DC grid; the DC bus voltage vector being a vector containing the values of the voltage change at the AC/DC converters, measured at the AC/DC converters, before, during and after a forced current change...
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Development of AC-DC power system simulator
International Nuclear Information System (INIS)
Ichikawa, Tatsumi; Ueda, Kiyotaka; Inoue, Toshio
1984-01-01
A modeling and realization technique is described for realtime plant dynamics simulation of nuclear power generating unit in AC-DC power system simulator. Dynamic behavior of reactor system and steam system is important for investigation a further adequate unit control and protection system to system faults in AC and DC power system. Each unit of two nuclear power generating unit in the power system simulator consists of micro generator, DC motors, flywheels and process computer. The DC motor and flywheel simulates dynamic characteristics of steam turbine, and process computer simulates plant dynamics by digital simulation. We have realized real-time plant dynamics simulation by utilizing a high speed process I/O and a high speed digital differential analyzing processor (DDA) in which we builted a newly developed simple plant model. (author)
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Modeling and simulation for micro DC motor based on simulink
Shen, Hanxin; Lei, Qiao; Chen, Wenxiang
2017-09-01
The micro DC motor has a large market demand but there is a lack of theoretical research for it. Through detailed analysis of the commutation process of micro DC motor commutator, based on micro DC motor electromagnetic torque equation and mechanical torque equation, with the help of Simulink toolkit, a triangle connection micro DC motor simulation model is established. By using the model, a sample micro DC motor are simulated, and an experimental measurements has been carried on the sample micro DC motor. It is found that the simulation results are consistent with theoretical analysis and experimental results.
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Comparison of two different high performance mixed signal controllers for DC/DC converters
DEFF Research Database (Denmark)
Jakobsen, Lars Tønnes; Andersen, Michael Andreas E.
2006-01-01
This paper describes how mixed signal controllers combining a cheap microcontroller with a simple analogue circuit can offer high performance digital control for DC/DC converters. Mixed signal controllers have the same versatility and performance as DSP based controllers. It is important to have...... an engineer experienced in microcontroller programming write the software algorithms to achieve optimal performance. Two mixed signal controller designs based on the same 8-bit microcontroller are compared both theoretically and experimentally. A 16-bit PID compensator with a sampling frequency of 200 k......Hz implemented in the 16 MIPS, 8-bit ATTiny26 microcontroller is demonstrated....
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Directory of Open Access Journals (Sweden)
Ramachandran Rakesh
2017-01-01
In this paper, design and implementation of an ultra-high efficiency isolated bi-directional dc-dc converter utilizing GaN devices is presented. Loss modelling of the GaN converter is also included in this paper. The converter has achieved a maximum measured efficiency of 98.8% in both directions of power flow, using the same power components. Hardware prototype of the converter along with the measured efficiency curve is also presented in this paper.
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Impact of Faults and Protection Methods on DC Microgrids Operation
DEFF Research Database (Denmark)
Bayati, Navid; Hajizadeh, Amin; N. Soltani, Mohsen
2018-01-01
with the DC Microgrid. This paper evaluates and presents a comprehensive review on the most recent studies in the DC Microgrids protection. Moreover, the fault behavior and characteristics of DC Microgrids, the effect of Constant Power Load (CPL) , and recent DC Microgrid protection methods are reviewed. Also...
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Blind signal processing algorithms under DC biased Gaussian noise
Kim, Namyong; Byun, Hyung-Gi; Lim, Jeong-Ok
2013-05-01
Distortions caused by the DC-biased laser input can be modeled as DC biased Gaussian noise and removing DC bias is important in the demodulation process of the electrical signal in most optical communications. In this paper, a new performance criterion and a related algorithm for unsupervised equalization are proposed for communication systems in the environment of channel distortions and DC biased Gaussian noise. The proposed criterion utilizes the Euclidean distance between the Dirac-delta function located at zero on the error axis and a probability density function of biased constant modulus errors, where constant modulus error is defined by the difference between the system out and a constant modulus calculated from the transmitted symbol points. From the results obtained from the simulation under channel models with fading and DC bias noise abruptly added to background Gaussian noise, the proposed algorithm converges rapidly even after the interruption of DC bias proving that the proposed criterion can be effectively applied to optical communication systems corrupted by channel distortions and DC bias noise.
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Bifurcation diagram features of a dc-dc converter under current-mode control
International Nuclear Information System (INIS)
Ruzbehani, Mohsen; Zhou Luowei; Wang Mingyu
2006-01-01
A common tool for analysis of the systems dynamics when the system has chaotic behaviour is the bifurcation diagram. In this paper, the bifurcation diagram of an ideal model of a dc-dc converter under current-mode control is analysed. Algebraic relations that give the critical points locations and describe the pattern of the bifurcation diagram are derived. It is shown that these simple algebraic and geometrical relations are responsible for the complex pattern of the bifurcation diagrams in such circuits. More explanation about the previously observed properties and introduction of some new ones are exposited. In addition, a new three-dimensional bifurcation diagram that can give better imagination of the parameters role is introduced
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Electrothermal model of choking-coils for the analysis of dc-dc converters
Energy Technology Data Exchange (ETDEWEB)
Gorecki, Krzysztof, E-mail: gorecki@am.gdynia.pl [Gdynia Maritime University, Department of Marine Electronics, Morska 83, Gdynia (Poland); Detka, Kalina [Pomeranian Higher School in Gdynia, Opata Hackiego 8-10, Gdynia (Poland)
2012-09-01
The paper concerns modelling the choking-coil for the needs of the electrothermal analysis of dc-dc converters. A new electrothermal model of the choking-coil is proposed. This model is dedicated for SPICE software and it takes into account nonlinearity of the dependences of the inductance on the current, selfheating and mutual thermal interactions between the core and the winding. The structure of this model is described in detail and its correctness is experimentally verified for the choking-coils with the ferrite and powder cores. Both the characteristics of the choking-coils and the buck converter with these choking-coils were considered. The satisfying agreement between the results of calculations and measurements is obtained.
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A VHF Class E DC-DC Converter with Self-Oscillating Gate Driver
DEFF Research Database (Denmark)
Andersen, Toke Meyer; Christensen, Søren K.; Knott, Arnold
2011-01-01
, is inherently resonant, and switching losses are greatly reduced by ensuring Zero Voltage Switching (ZVS) of the power semiconductor devices. A design method to ensure ZVS operation when combining the inverter, rectifier, and gate driver is provided. Several parasitic effects and their influence on converter......This paper describes the analysis and design of a DC-DC converter topology which is operational at frequencies in the Very High Frequency (VHF) band ranging from 30 MHz − 300 MHz. The presented topology, which consists of a class E inverter, class E rectifier, and self-oscillating gate driver...... operation are discussed, and measurement results of a 100 MHz prototype converter are presented and evaluated. The designed prototype converter verifies the described topology....
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ALA-PDT mediated DC vaccine for skin squamous cell carcinoma
Ji, Jie; Fan, Zhixia; Zhou, Feifan; Wang, Xiaojie; Shi, Lei; Zhang, Haiyan; Wang, Peiru; Yang, Degang; Zhang, Linglin; Wang, Xiuli; Chen, Wei R.
2015-03-01
Dendritic cell (DC) based vaccine has emerged as a promising immunotherapy for cancers. However, most DC vaccines so far have only achieved limited success in cancer treatment. Photodynamic therapy (PDT), an established cancer treatment strategy, can cause immunogenic apoptosis to induce an effective antitumor immune response. In this study, we developed a DC-based cancer vaccine using immunogenic apoptotic tumor cells induced by 5-aminolevulinic acid (ALA) mediated PDT. The maturation of DCs induced by PDT-treated apoptotic cells was evaluated. The anti-tumor immunity of ALA-PDT-DC vaccine was tested with mouse model. We observed the maturations of DCs potentiated by ALA-PDT treated tumor cells, including phenotypic maturation (upregulation of surface expression of MHC-II, DC80, and CD86), and functional maturation (enhanced capability to secret INF-Υ and IL-12). ALA-PDT-DC vaccine mediated by apoptotic cells provided protection against tumor in mice, far stronger than that of DC vaccine obtained from freeze/thaw treated tumor cells. Our results indicate that immunogenic apoptotic tumor cells can be more effective in enhancing DC-based cancer vaccine, which could improve the clinical application of PDT- DC vaccines.
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DC KIDS COUNT e-Databook Indicators
DC Action for Children, 2012
2012-01-01
This report presents indicators that are included in DC Action for Children's 2012 KIDS COUNT e-databook, their definitions and sources and the rationale for their selection. The indicators for DC KIDS COUNT represent a mix of traditional KIDS COUNT indicators of child well-being, such as the number of children living in poverty, and indicators of…
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DEFF Research Database (Denmark)
Zhang, Zhe; Ouyang, Ziwei; Thomsen, Ole Cornelius
2012-01-01
Electrical power system in future uninterruptible power supply (UPS) or electrical vehicle (EV) may employ hybrid energy sources, such as fuel cells and super-capacitors. It will be necessary to efficiently draw the energy from these two sources as well as recharge the energy storage elements...... by the DC bus. In this paper, a bidirectional isolated DC-DC converter controlled by phase-shift and duty cycle for the fuel cell hybrid energy system is analyzed and designed. The proposed topology minimizes the number of switches and their associated gate driver components by using two high frequency...
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of Spirostachys africana complicated
African Journals Online (AJOL)
C Scott, FCPaed (SA). Department of Paediatrics, Red Cross War Memorial Children's Hospital and University of Cape Town. N P Khumalo, MB ChB, .... Jeung YJ, Lee JY, Oh MJ, Choi DC, Lee BJ. Comparison of the causes and clinical features of drug rash with eosinophilia and systemic symptoms and Stevens-Johnson ...
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LPV model for PV cell and fractional control of DC/DC converter for photovoltaic systems
Martínez González, Rubén; Bolea Monte, Yolanda; Grau Saldes, Antoni; Martínez García, Herminio
2011-01-01
This paper deals with the fractional modelling of a DC-DC converter, suitable in solar-powered electrical generation systems, and the design of a fractional controller for the aforementioned switching converter. A new model for PV cells is proposed in order to obtain a linear equation for V-I characteristic via scheduling dependence of temperature and irradiance. Due to the fractional nature of the ultracapacitors this kind of controller gives a suitable and good performance. Peer Reviewed
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LPV model for PV cells and fractional control of DC/DC converter for photovoltaic systems
Martínez González, Rubén; Bolea Monte, Yolanda; Grau Saldes, Antoni; Martínez García, Herminio
2011-01-01
This paper deals with the fractional modelling of a DC-DC converter, suitable in solar-powered electrical generation systems, and the design of a fractional controller for the aforementioned switching converter. A new model for PV cells is proposed in order to obtain a linear equation for VI characteristic via scheduling dependence of temperature and irradiance. Due to the fractional nature of the ultracapacitors this kind of controller gives a suitable and good performance. Peer Rev...
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GaN-based High Efficiency Bidirectional DC-DC Converter with 10 MHz Switching Frequency
DEFF Research Database (Denmark)
Kruse, Kristian; Zhang, Zhe; Elbo, Mads
2017-01-01
-isolated bidirectional DC-DC converter equipped with Gallium Nitride (GaN) semiconductor transistors is presented. The converter’s operation principles, zero-voltage switching (ZVS) constraints and dead-time effects are studied. Moreover, the optimization and tradeoffs on the adopted high-frequency inductor...... are achieved. Moreover, the measured losses can match the theoretically calculated counterparts well, therefore the design and analysis are verified. However, from the experimental test carried out, it can also be seen, that making a compact converter, even for a GaN-based one, operate at 10 MHz and 100 W...
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Directory of Open Access Journals (Sweden)
Mikhail Tsypkin
2005-10-01
Full Text Available The Russian military largely went below the radar of Western interest after the disintegration of the Soviet Union. More than a decade after the creation of the Armed Forces of the Russian Federation, they have become again the object of interest for scholars – this time, both Western and Russian, as demonstrated by the reviewed volume, whose editors assembled a group of extraordinarily knowledgeable experts from Russia and the West. In his introduction, Steven Miller explains that the purp...
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DEFF Research Database (Denmark)
Liu, Dong; Deng, Fujin; Zhang, Qi
2018-01-01
The current imbalance among the two input capacitors is one of the important issues of the half-bridge threelevel (HBTL) DC/DC converter, which would affect system performance and reliability. In this paper, a zero-voltage switching (ZVS) pulse-wide modulation (PWM) strategy including two operation...
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Directory of Open Access Journals (Sweden)
Bankov Dimitrov Nikolay
2012-01-01
Full Text Available This work examines a series resonant DC/DC optimal trajectory controlled converter during operation above resonant frequency, taking into account the influence of the snubbers and matching transformer. We obtain expressions for the load characteristics, boundary curves between possible modes and limits of the soft commutation area. Computer simulation and experimental observation confirm the theoretical results.
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DEFF Research Database (Denmark)
Lu, Xiaonan; Guerrero, Josep M.; Sun, Kai
2014-01-01
Droop control is the basic control method for load current sharing in dc microgrid applications. The conventional dc droop control method is realized by linearly reducing the dc output voltage as the output current increases. This method has two limitations. First, with the consideration of line...... resistance in a droop-controlled dc microgrid, since the output voltage of each converter cannot be exactly the same, the output current sharing accuracy is degraded. Second, the DC bus voltage deviation increases with the load due to the droop action. In this paper, in order to improve the performance......, and the LBC system is only used for changing the values of the dc voltage and current. Hence, a decentralized control scheme is accomplished. The simulation test based on Matlab/Simulink and the experimental validation based on a 2×2.2 kW prototype were implemented to demonstrate the proposed approach....
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Hyperolius argus (Anura) in Natal: taxonomy, biogeography and ...
African Journals Online (AJOL)
South African frogs of the genus. Hyperolius in the Museum of Comparative Zoology,. Cambridge, Massachusetts. Ann. Transv. Mus. 20: 283 - 291. PARKER, H.W. 1930. A collection of frogs from Portuguese East. Africa. Proc. zool. Soc. Lond. 1930: 897 - 905. PASSMORE, N.I. & CARRUTHERS, V.C. 1979. South African.
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Fuzzy Controlled Parallel AC-DC Converter for PFC
Directory of Open Access Journals (Sweden)
M Subba Rao
2011-01-01
Full Text Available Paralleling of converter modules is a well-known technique that is often used in medium-power applications to achieve the desired output power by using smaller size of high frequency transformers and inductors. In this paper, a parallel-connected single-phase PFC topology using flyback and forward converters is proposed to improve the output voltage regulation with simultaneous input power factor correction (PFC and control. The goal of the control is to stabilize the output voltage of the converter against the load variations. The paper presents the derivation of fuzzy control rules for the dc/dc converter circuit and control algorithm for regulating the dc/dc converter. This paper presents a design example and circuit analysis for 200 W power supply. The proposed approach offers cost effective, compact and efficient AC/DC converter by the use of parallel power processing. MATLAB/SIMULINK is used for implementation and simulation results show the performance improvement.
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International Nuclear Information System (INIS)
Bernard, S.R.
1983-01-01
Stevens measured the distribution, retention, and excretion of U-233 in seven beagles each given a single injection of U-233 citrate [2.8 μCi/kg U-233 (VI) (approx.3 mg/dog)]. These data, when plotted together with results obtained with the ICRP (Pub. 30) retention functions for purposes of comparison, are seen to differ only slightly from the ICRP-30 model. The number of transformations in the body, over a fifty-year period agree within a factor of 2. A three-compartment mammillary model has been parameterized from the data of Stevens by the method of Bernard. Retention in tissues of the body is represented by a linear combination of three compartments. The data plots for the dogs and ICRP-30 model will be presented and discussed together with the three compartment mammillary model for U-233 retention, distribution, and excretion. 3 figs., 2 tabs
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single-phase dc phase dc-ac boost converter ac boost converter
African Journals Online (AJOL)
User
systems, need to step-up the DC input voltage. increase the ... design also makes for extra parts, greater system and weight, [1-3]. ... proposes a new design for high performance sin ... SYSTEM ANALYSIS. 2. ..... from the simulation study.
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Move to Solar-DC at Home Premises
Indian Academy of Sciences (India)
48V DC line as an additional power line at home. Highly power-efficient usage of Solar; Low-power from grid alone converted from AC-DC. Designed to have minimal loss. Battery can be added with higher efficiency (no convertors), if required.
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Electronic DC transformer with high power density
Pavlovský, M.
2006-01-01
This thesis is concerned with the possibilities of increasing the power density of high-power dc-dc converters with galvanic isolation. Three cornerstones for reaching high power densities are identified as: size reduction of passive components, reduction of losses particularly in active components
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A parameter estimation for DC servo motor by using optimization process
International Nuclear Information System (INIS)
Arjoni Amir
2010-01-01
Modeling and simulation parameters of DC servo motor using Matlab Simulink software have been done. The objective to define the DC servo motor parameter estimation is to get DC servo motor parameter values (B, La, Ra, Km, J) which are significant value that can be used for actuation process of control systems. In the analysis of control systems DC the servo motor expressed by transfer function equation to make faster to be analyzed as a component of the actuator. To obtain the data model parameters and initial conditions of the DC servo motors is then carried out the processor modeling and simulation in which the DC servo motor combined with other components. To obtain preliminary data of the DC servo motor parameters as estimated venue, it is obtained from the data factory of the DC servo motor. The initial data parameters of the DC servo motor are applied for the optimization process by using nonlinear least square algorithm and minimize the cost function value so that the DC servo motors parameter values are obtained significantly. The result of the optimization process of the DC servo motor parameter values are B = 0.039881, J= 1.2608e-007, Km = 0.069648, La = 2.3242e-006 and Ra = 1.8837. (author)
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Application of digital control techniques for satellite medium power DC-DC converters
Skup, Konrad R.; Grudzinski, Pawel; Nowosielski, Witold; Orleanski, Piotr; Wawrzaszek, Roman
2010-09-01
The objective of this paper is to present a work concerning a digital control loop system for satellite medium power DC-DC converters that is done in Space Research Centre. The whole control process of a described power converter bases on a high speed digital signal processing. The paper presents a development of a FPGA digital controller for voltage mode stabilization that was implemented using VHDL. The described controllers are a classical digital PID controller and a bang-bang controller. The used converter for testing is a simple model of 5-20 W, 200 kHz buck power converter. A high resolution digital PWM approach is presented. Additionally a simple and effective solution of filtering of an analog-to-digital converter output is presented.
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Directory of Open Access Journals (Sweden)
Gusti Rinaldi Zulkarnain
2017-01-01
Full Text Available Seiring dengan berkembangnya pembangkit listrik yang menggunakan photovoltaic sebagai salah satu energi terbarukan, maka berdampak kepada perkembangan teknologi konverter. Tegangan output dari photovoltaic masih perlu ditingkatkan agar mampu dihubungkan pada sistem grid. Salah satu pengembangan topologi konverter boost untuk aplikasi keluaran photovoltaic yaitu konverter DC-DC rasio tinggi berbasis pensaklaran kapasitor dan induktor terkopel. Konverter ini merupakan pengembangan dari konverter gabungan boost-flyback yang ditambahkan rangkaian pensaklaran kapasitor. Kelebihan dari konverter ini adalah memiliki rasio konversi dan efisiensi yang tinggi. Konverter ini mampu menjaga tegangan output konstan ketika tegangan inputnya berubah-ubah. Konverter ini sangan cocok diaplikasikan pada sumber energi alternatif yang menghasilkan tegangan DC rendah seperti photovoltaic.
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Reliability of capacitors for DC-link applications - An overview
DEFF Research Database (Denmark)
Wang, Huai; Blaabjerg, Frede
2013-01-01
DC-link capacitors are an important part in the majority of power electronic converters which contribute to cost, size and failure rate on a considerable scale. From capacitor users' viewpoint, this paper presents a review on the improvement of reliability of DC-link in power electronic converters...... from two aspects: 1) reliability-oriented DC-link design solutions; 2) conditioning monitoring of DC-link capacitors during operation. Failure mechanisms, failure modes and lifetime models of capacitors suitable for the applications are also discussed as a basis to understand the physics......-of-failure. This review serves to provide a clear picture of the state-of-the-art research in this area and to identify the corresponding challenges and future research directions for capacitors and their DC-link applications....
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Development of toroid-type HTS DC reactor series for HVDC system
Energy Technology Data Exchange (ETDEWEB)
Kim, Kwangmin, E-mail: kwangmin81@gmail.com [Changwon National University, 55306 Sarim-dong, Changwon 641-773 (Korea, Republic of); Go, Byeong-Soo; Park, Hea-chul; Kim, Sung-kyu; Kim, Seokho [Changwon National University, 55306 Sarim-dong, Changwon 641-773 (Korea, Republic of); Lee, Sangjin [Uiduk University, Gyeongju 780-713 (Korea, Republic of); Oh, Yunsang [Vector Fields Korea Inc., Pohang 790-834 (Korea, Republic of); Park, Minwon; Yu, In-Keun [Changwon National University, 55306 Sarim-dong, Changwon 641-773 (Korea, Republic of)
2015-11-15
Highlights: • The authors developed the 400 mH, 400 A class toroid-type HTS DC reactor system. • The target temperature, inductance and operating current are under 20 K at magnet, 400 mH and 400 A, respectively. All target performances of the HTS DC reactor were achieved. • The HTS DC reactor was conducted through the interconnection operation with a LCC type HVDC system. • Now, the authors are studying the 400 mH, 1500 A class toroid-type HTS DC reactor for the next phase HTS DC reactor. - Abstract: This paper describes design specifications and performance of a toroid-type high-temperature superconducting (HTS) DC reactor. The first phase operation targets of the HTS DC reactor were 400 mH and 400 A. The authors have developed a real HTS DC reactor system during the last three years. The HTS DC reactor was designed using 2G GdBCO HTS wires. The HTS coils of the toroid-type DC reactor magnet were made in the form of a D-shape. The electromagnetic performance of the toroid-type HTS DC reactor magnet was analyzed using the finite element method program. A conduction cooling method was adopted for reactor magnet cooling. The total system has been successfully developed and tested in connection with LCC type HVDC system. Now, the authors are studying a 400 mH, kA class toroid-type HTS DC reactor for the next phase research. The 1500 A class DC reactor system was designed using layered 13 mm GdBCO 2G HTS wire. The expected operating temperature is under 30 K. These fundamental data obtained through both works will usefully be applied to design a real toroid-type HTS DC reactor for grid application.
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Development of toroid-type HTS DC reactor series for HVDC system
International Nuclear Information System (INIS)
Kim, Kwangmin; Go, Byeong-Soo; Park, Hea-chul; Kim, Sung-kyu; Kim, Seokho; Lee, Sangjin; Oh, Yunsang; Park, Minwon; Yu, In-Keun
2015-01-01
Highlights: • The authors developed the 400 mH, 400 A class toroid-type HTS DC reactor system. • The target temperature, inductance and operating current are under 20 K at magnet, 400 mH and 400 A, respectively. All target performances of the HTS DC reactor were achieved. • The HTS DC reactor was conducted through the interconnection operation with a LCC type HVDC system. • Now, the authors are studying the 400 mH, 1500 A class toroid-type HTS DC reactor for the next phase HTS DC reactor. - Abstract: This paper describes design specifications and performance of a toroid-type high-temperature superconducting (HTS) DC reactor. The first phase operation targets of the HTS DC reactor were 400 mH and 400 A. The authors have developed a real HTS DC reactor system during the last three years. The HTS DC reactor was designed using 2G GdBCO HTS wires. The HTS coils of the toroid-type DC reactor magnet were made in the form of a D-shape. The electromagnetic performance of the toroid-type HTS DC reactor magnet was analyzed using the finite element method program. A conduction cooling method was adopted for reactor magnet cooling. The total system has been successfully developed and tested in connection with LCC type HVDC system. Now, the authors are studying a 400 mH, kA class toroid-type HTS DC reactor for the next phase research. The 1500 A class DC reactor system was designed using layered 13 mm GdBCO 2G HTS wire. The expected operating temperature is under 30 K. These fundamental data obtained through both works will usefully be applied to design a real toroid-type HTS DC reactor for grid application.
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Modelling of flow phenomena during DC casting
Zuidema, J.
2005-01-01
Modelling of Flow Phenomena during DC Casting Jan Zuidema The production of aluminium ingots, by semi-continuous casting, is a complex process. DC Casting stands for direct chill casting. During this process liquid aluminium transforms to solid aluminium while cooling down. This is not an
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Superconducting DC homopolar motors for ship propulsion
Energy Technology Data Exchange (ETDEWEB)
Heiberger, M.; Reed, M.R.; Creedon, W.P.; O' Hea, B.J. [General Atomic (United States)
2000-07-01
Superconducting DC homopolar motors have undergone recent advances in technology, warranting serious consideration of their use for ship propulsion. Homopolar motor propulsion is now practical because of two key technology developments: cryogen-free superconducting refrigeration and high performance motor fiber brushes. These compact motors are ideal for podded applications, where reduced drag and fuel consumption are predicted. In addition, the simple DC motor controller is more efficient and reliable compared with AC motor controllers. Military ships also benefit from increased stealth implicit in homopolar DC excitation, which also allows the option for direct hull or pod mounting. (authors)
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Overvoltage protection in DC power systems; Ueberspannungsschutz in Gleichstromanlagen
Energy Technology Data Exchange (ETDEWEB)
Birkl, Josef; Zahlmann, Peter [Dehn + Soehne GmbH + Co.KG, Neumarkt (Germany)
2012-02-15
The utilisation of DC power systems has increased dramatically in the recent years. In addition to traditional DC applications such as in telecommunications and railway engineering a variety of DC applications arise due to a rapid spread of photovoltaic systems. Current projects for the e-mobility expand the scope of application.
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Thyristors for dc transmission
Energy Technology Data Exchange (ETDEWEB)
1966-05-06
As a first stage towards determining the feasibility of applying thyristors to hvdc converter terminals, the Westinghouse Electric Corporation has built a converter laboratory capable of testing thyristors under conditions similar to those which would have to be met in a 200 kV dc system. The equipment has been designed to test a 5 kV 600 A group of thyrisotrs, elevated 200 kV above earth. This rating has been chosen so that there would be a sufficient number of thyristors in series to enable the gating and voltage division characteristics to be investigated and at the same time the group could be operated at a potential equivalent to a complete 200 kV dc bridge.
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Hierarchical Control of Parallel AC-DC Converter Interfaces for Hybrid Microgrids
DEFF Research Database (Denmark)
Lu, Xiaonan; Guerrero, Josep M.; Sun, Kai
2014-01-01
In this paper, a hierarchical control system for parallel power electronics interfaces between ac bus and dc bus in a hybrid microgrid is presented. Both standalone and grid-connected operation modes in the dc side of the microgrid are analyzed. Concretely, a three-level hierarchical control system...... equal or proportional dc load current sharing. The common secondary control level is designed to eliminate the dc bus voltage deviation produced by the droop control, with dc bus voltage in the hybrid microgrid boosted to an acceptable range. After guaranteeing the performance of the dc side standalone...
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International Nuclear Information System (INIS)
Hardik, P. Desai; Ranjan Maheshwari
2011-01-01
This paper investigates the interest focused on employing parallel connected dc-dc converter with high tracking effectiveness under wide variation in environmental conditions (Insolation) and wide load variation. dc-dc converter is an essential part of the stand alone PV system. Paper also presents an approach on how duty cycle for maximum power position (MPP) is adjusted by taking care of varying load conditions and without iterative steps. Synchronized PWM pulses are employed for the converter. High tracking efficiency is achieved with continuous input and inductor current. In this approach, the converter can he utilized in buck as well in boost mode. The PV system simulation was verified and experimental results were in agreement to the presented scheme. (authors)
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International Nuclear Information System (INIS)
Memon, A.A.
2013-01-01
This paper presents a gate driver circuit for the switching devices used in the asymmetrical converter for a switched reluctance machine with reduced number of isolated dc/dc converters. Isolation required in the gate driver circuit of switching devices is indispensable. For the purpose of isolation different arrangements may be used such as pulse transformers. The dc/dc converter for isolation and powering the gate drive circuits is suitable, cheaper in cost and simple to implement. It is also significant that required number of isolation converters is much less than the switches used in converter. In addition, a simple logic circuit has been presented for producing the gate signals at correct phase sequence which is compared with the gated signals directly obtained from the encoder of an existing machine. (author)
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International Nuclear Information System (INIS)
Su, Yu-Hao; Liu, Yuan-Ping; Wu, Wen-Jong; Lee, Chih-Kung; Vasic, Dejan; Costa, Francois
2013-01-01
The objective of this study was to increase the output current and power in a piezoelectric transformer (PT)-based DC/DC converter by using a cooling system. It is known that the output current of a PT is limited by temperature build-up because of losses, especially when driving at high vibration velocity. Although connecting different inductive circuits at the PT secondary terminal can increase the output current, the root cause of the temperature build-up problem has not yet been solved. This paper presents a study of a PT with cooling system in a DC/DC converter with a commonly used full-bridge rectifier and current-doubler rectifier. The advantages and disadvantages of the proposed technique were investigated. A theoretical–phenomenological model was developed to explain the relationship between the losses and the temperature rise. It will be shown that the vibration velocity as well as heat generation increases the losses. In our design, the maximum output current capacity can increase by 100% when the temperature of operation of the PT is kept below 55 ° C. The study comprises a theoretical part and experimental proof-of-concept demonstration of the proposed design method. (paper)
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Energy Technology Data Exchange (ETDEWEB)
Kraft, C. [Lucent Technologies, Inc., Naperville, IL (United States)
2000-07-01
Telecommunications switching equipment has been moving toward a distributed DC power concept where 48 volts (or other telephone office voltage) is routed directly onto circuit boards via backplanes. This higher DC voltage is then converted on the circuit board to 5 volts, 3 volts or other logic voltage. One problem with this approach is the generation of a considerable amount of conducted noise current on 48 volt supply leads. Unless some mitigation is used, this noise current, when added to such currents from other boards in the system, can cause failure of electromagnetic compatibility (EMC) tests required by international standards such as EN 300-386-2 [1], or EN 55022 [2], and hence, hurt the ability of the equipment to be marketed. This paper describes in detail the type and frequency range of noise generated by typical 48 volt DC-DC converters as measured in EMC tests on power feeder leads. It provides an analysis of the nature of this noise, a comparison with the requirements of the international standards, and a set of mitigation techniques that not only remove the noise, but satisfy various lightning and grounding requirements, including those of the USA and Europe. (orig.)
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Mucous membrane grafting for the post-Steven-Johnson syndrome symblepharon: A case report
Directory of Open Access Journals (Sweden)
Jayanta Kumar Das
2011-01-01
Full Text Available An 18-year-old woman was referred with late sequelae of chloroquine-induced Steven-Johnson syndrome. At the time of presentation, the symblepharon was involving the upper lids to almost the whole of the cornea, and part of the lower bulbar conjunctiva with the lower lid bilaterally. Other ocular examinations were not possible due to the symblepharon. B-scan ultrasonography revealed acoustically clear vitreous, normal chorioretinal thickness, and normal optic nerve head, with an attached retina. Conjunctivo-corneal adhesion released by superficial lamellar dissection of the cornea. Ocular surface reconstruction was carried out with a buccal mucous membrane. A bandage contact lens was placed over the cornea followed by the symblepharon ring to prevent further adhesion. The mucosal graft was well taken up along with corneal re-epithelization. Best corrected visual acuity of 20/120 in both sides after 1 month and 20/80 after 3 months was achieved and maintained till the 2.5-year follow-up.
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DEFF Research Database (Denmark)
Park, Kiwoo; Chen, Zhe
2013-01-01
This paper presents a parallel-connected Single Active Bridge (SAB) dc-dc converter for high-power applications. Paralleling lower-power converters can lower the current rating of each modular converter and interleaving the outputs can significantly reduce the magnitudes of input and output curre...
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DC-STAMP Is an Osteoclast Fusogen Engaged in Periodontal Bone Resorption.
Wisitrasameewong, W; Kajiya, M; Movila, A; Rittling, S; Ishii, T; Suzuki, M; Matsuda, S; Mazda, Y; Torruella, M R; Azuma, M M; Egashira, K; Freire, M O; Sasaki, H; Wang, C Y; Han, X; Taubman, M A; Kawai, T
2017-06-01
Dendritic cell-specific transmembrane protein (DC-STAMP) plays a key role in the induction of osteoclast (OC) cell fusion, as well as DC-mediated immune regulation. While DC-STAMP gene expression is upregulated in the gingival tissue with periodontitis, its pathophysiological roles in periodontitis remain unclear. To evaluate the effects of DC-STAMP in periodontitis, anti-DC-STAMP-monoclonal antibody (mAb) was tested in a mouse model of ligature-induced periodontitis ( n = 6-7/group) where Pasteurella pneumotropica ( Pp)-reactive immune response activated T cells to produce receptor activator of nuclear factor kappa-B ligand (RANKL), which, in turn, promotes the periodontal bone loss via upregulation of osteoclastogenesis. DC-STAMP was expressed on the cell surface of mature multinuclear OCs, as well as immature mononuclear OCs, in primary cultures of RANKL-stimulated bone marrow cells. Anti-DC-STAMP-mAb suppressed the emergence of large, but not small, multinuclear OCs, suggesting that DC-STAMP is engaged in the late stage of cell fusion. Anti-DC-STAMP-mAb also inhibited pit formation caused by RANKL-stimulated bone marrow cells. Attachment of ligature to a second maxillary molar induced DC-STAMP messenger RNA and protein, along with elevated tartrate-resistant acid phosphatase-positive (TRAP+) OCs and alveolar bone loss. As we expected, systemic administration of anti-DC-STAMP-mAb downregulated the ligature-induced alveolar bone loss. Importantly, local injection of anti-DC-STAMP-mAb also suppressed alveolar bone loss and reduced the total number of multinucleated TRAP+ cells in mice that received ligature attachment. Attachment of ligature induced significantly elevated tumor necrosis factor-α, interleukin-1β, and RANKL in the gingival tissue compared with the control site without ligature ( P < 0.05), which was unaffected by local injection with either anti-DC-STAMP-mAb or control-mAb. Neither in vivo anti- Pp IgG antibody nor in vitro anti- Pp T
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High Brightness Injectors Based On Photocathode DC Gun
International Nuclear Information System (INIS)
B. Yunn
2001-01-01
Sample results of new injector design method based on a photocathode dc gun are presented, based on other work analytically proving the validity of the emittance compensation scheme for the case even when beam bunching is involved. We have designed several new injectors appropriate for different bunch charge ranges accordingly. Excellent beam quality produced by these injectors clearly shows that a photocathode dc gun can compete with a rf gun on an equal footing as the source of an electron beam for the bunch charge ranging up to 2 nano Coulomb (nC). This work therefore elevates a dc gun based injector to the preferred choice for many ongoing high brightness accelerator projects considering the proven operational stability and high average power capability of the dc gun
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DC motor speed control using fuzzy logic controller
Ismail, N. L.; Zakaria, K. A.; Nazar, N. S. Moh; Syaripuddin, M.; Mokhtar, A. S. N.; Thanakodi, S.
2018-02-01
The automatic control has played a vital role in the advance of engineering and science. Nowadays in industries, the control of direct current (DC) motor is a common practice thus the implementation of DC motor controller speed is important. The main purpose of motor speed control is to keep the rotation of the motor at the present speed and to drive a system at the demand speed. The main purpose of this project is to control speed of DC Series Wound Motor using Fuzzy Logic Controller (FLC). The expectation of this project is the Fuzzy Logic Controller will get the best performance compared to dc motor without controller in terms of settling time (Ts), rise time (Tr), peak time (Tp) and percent overshoot (%OS).
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Directory of Open Access Journals (Sweden)
Sanjeevikumar Padmanaban
2017-01-01
Full Text Available Classical DC-DC converters used in high voltage direct current (HVDC power transmission systems, lack in terms of efficiency, reduced transfer gain and increased cost with sensor (voltage/current numbers. Besides, the internal self-parasitic behavior of the power components reduces the output voltage and efficiency of classical HV converters. This paper deals with extra high-voltage (EHV dc-dc boost converter by the application of voltage-lift technique to overcome the aforementioned deficiencies. The control strategy is based on classical proportional-integral (P-I and fuzzy logic closed-loop controller to get high and stable output voltage. Complete hardware prototype of EHV is implemented and experimental tasks are carried out with digital signal processor (DSP TMS320F2812. The control algorithms P-I, fuzzy logic and the pulse-width modulation (PWM signals for N-channel MOSFET device are performed by the DSP. The experimental results provided show good conformity with developed hypothetical predictions. Additionally, the presented study confirms that the fuzzy logic controller provides better performance than classical P-I controller under different perturbation conditions.
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2010-11-09
... Jersey Avenue, SE., Washington, DC 20590. FOR FURTHER INFORMATION CONTACT: Wahib Mina, Aerospace Engineer... requested using the procedures found in 14 CFR 39.19. Send information to ATTN: Wahib Mina, Aerospace...
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Autonomous Control Strategy of DC Microgrid for Islanding Mode Using Power Line Communication
Directory of Open Access Journals (Sweden)
Dong-Keun Jeong
2018-04-01
Full Text Available This paper proposes a DC-bus signaling (DBS method for autonomous power management in a DC microgrid, used to improve its reliability. Centralized power management systems require communication between the power sources and loads. However, the DBS method operates based on the common DC-bus voltage and does not require communication. Based on the DC-bus voltage band, the DC-bus voltage can be used to inform the status of the DC-bus in various scenarios. The DC microgrid operates independently to maintain the system stably in the DC-bus voltage band. The DC microgrid can be divided into a grid-connected mode and an islanding mode. This paper proposes a control strategy based on power management of various independent components in islanding mode. In addition, the autonomous control method for switching the converter’s operation between grid-connected mode and islanding mode is proposed. A DC microgrid test bed consisting of a grid-connected AC/DC converter, a bidirectional DC/DC converter, a renewable energy simulator, DC home appliances and a DC-bus protector is used to test the proposed control strategy. The proposed autonomous control strategy is experimentally verified using the DC microgrid test bed.
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Practical Design Guidelines of qZSI Based Step-Up DC/DC Converter
Zakis, Janis; Vinnikov, Dmitri; Roasto, Indrek; Jalakas, Tanel
2010-01-01
This paper presents some design guidelines for a new voltage fed step-up DC/DC isolated converter. The most significant advantage of proposed converter is voltage buck-boost operation on single stage. The most promising application for proposed converter is in the field of distributed power generation e.g. fuel cells or photovoltaic. The most sensitive issues - such as power losses caused by high currents in the input side of converter and high transient overvoltages across the inverter bridge caused by stray inductances were discussed and solved. The proposals and recommendations to overcome these issues are given in the paper. The Selection and design guidelines of converter elements are proposed and explained. The prototype of proposed converter was built and experimentally tested. Some results are presented and evaluated.
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Electrostatic analysis of 750 keV DC accelerator
International Nuclear Information System (INIS)
Kumar, Abhay; Dwivedi, Jishnu; Jana, Arup Ratan
2011-01-01
The indigenously developed 750 keV DC accelerator working at RRCAT for the last 5 years uses SF 6 at 6 bar pressure as the insulating gas. The green house potential of this gas is about 22,000 times more than that of CO 2 gas. An electrostatic analysis of this accelerator was performed in order to probe the necessity of using this gas with a very elaborate gas handling system. The DC accelerator is approximated by a 2-D axisymmetric model in ANSYS and voltages were defined at the individual stages of the accelerating tube. The result of the study shows that the present design needs SF 6 gas and the pressure vessel dimensions need to be modified to operate the DC accelerator with environmentally friendly N 2 -CO 2 mixture. This paper presents the methodology of the analysis, discusses the DC accelerator finite element model and presents the results of the analysis. The paper also proposes changes in the DC accelerator design to run the accelerator with N 2 -CO 2 mixture. (author)
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21 CFR 82.1260 - D&C Orange No. 10.
2010-04-01
... 21 Food and Drugs 1 2010-04-01 2010-04-01 false D&C Orange No. 10. 82.1260 Section 82.1260 Food... CERTIFIED PROVISIONALLY LISTED COLORS AND SPECIFICATIONS Drugs and Cosmetics § 82.1260 D&C Orange No. 10. The color additive D&C Orange No. 10 shall conform in identity and specifications to the requirements...
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21 CFR 74.2255 - D&C Orange No. 5.
2010-04-01
... 21 Food and Drugs 1 2010-04-01 2010-04-01 false D&C Orange No. 5. 74.2255 Section 74.2255 Food and... ADDITIVES SUBJECT TO CERTIFICATION Cosmetics § 74.2255 D&C Orange No. 5. (a) Identity and specifications. The color additive D&C Orange No. 5 shall conform in identity and specifications to the requirements...
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21 CFR 74.2254 - D&C Orange No. 4.
2010-04-01
... 21 Food and Drugs 1 2010-04-01 2010-04-01 false D&C Orange No. 4. 74.2254 Section 74.2254 Food and... ADDITIVES SUBJECT TO CERTIFICATION Cosmetics § 74.2254 D&C Orange No. 4. (a) Identity and specifications. The color additive D&C Orange No. 4 shall conform in identity and specifications to the requirements...
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21 CFR 82.1261 - D&C Orange No. 11.
2010-04-01
... 21 Food and Drugs 1 2010-04-01 2010-04-01 false D&C Orange No. 11. 82.1261 Section 82.1261 Food... CERTIFIED PROVISIONALLY LISTED COLORS AND SPECIFICATIONS Drugs and Cosmetics § 82.1261 D&C Orange No. 11. The color additive D&C Orange No. 11 shall conform in identity and specifications to the requirements...
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21 CFR 74.2260 - D&C Orange No. 10.
2010-04-01
... 21 Food and Drugs 1 2010-04-01 2010-04-01 false D&C Orange No. 10. 74.2260 Section 74.2260 Food... COLOR ADDITIVES SUBJECT TO CERTIFICATION Cosmetics § 74.2260 D&C Orange No. 10. (a) Identity and specifications. The color additive D&C Orange No. 10 shall conform in identity and specifications to the...
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21 CFR 74.2261 - D&C Orange No. 11.
2010-04-01
... 21 Food and Drugs 1 2010-04-01 2010-04-01 false D&C Orange No. 11. 74.2261 Section 74.2261 Food... COLOR ADDITIVES SUBJECT TO CERTIFICATION Cosmetics § 74.2261 D&C Orange No. 11. (a) Identity and specifications. The color additive D&C Orange No. 11 shall conform in identity and specifications to the...
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International Nuclear Information System (INIS)
Fernandez, Luis M.; Garcia, Pablo; Garcia, Carlos Andres; Jurado, Francisco
2011-01-01
Research highlights: → Hybrid electric power system for a real surface tramway. → Hybrid system based on PEM fuel cell with dc/dc converter and Ni-MH battery. → New control strategy for the energy management of the tramway. → Hybrid system demonstrated to meet appropriate driving cycle of the tramway. -- Abstract: This paper presents a hybrid electric power system for a real surface tramway. The hybrid system consists of two electrical energy sources integrating a single dc/dc converter to provide the power demanded by the tramway loads (four electric traction motors and auxiliary services): (1) a Polymer Electrolyte Membrane (PEM) fuel cell (FC) as the primary and (2) a rechargeable Ni-MH battery as electrical energy storage to supplement the FC over the driving cycle. According to the requirements of the real driving cycle of the tramway, it was considered a 200 kW PEM FC system with two FCs connected in parallel and a 34 Ah Ni-MH battery. The PEM FC and Ni-MH battery models were designed from commercially available components. The power conditioning system provides the appropriate power for the tramway. It is composed of: (1) a unique dc/dc boot converter which adapts the FC output voltage to the 750 V traction standard dc bus; (2) three phase inverters to drive properly each electric motors; and (3) a braking chopper to dissipate excess of regenerative braking energy. Suitable state machine control architecture is presented for the hybrid system, its objective being to provide demanded power by the driving cycle, optimizing the energy generated. Following this objective, a new state machine control strategy based on eight states decides the operating point of each component of the system and a cascade control structure allows achieving the operating points determined by the strategy. Simulation results of the real driving cycle of the tramway check the adequacy of the hybrid electric power system.
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Energy Technology Data Exchange (ETDEWEB)
Fernandez, Luis M., E-mail: luis.fernandez@uca.e [Department of Electrical Engineering, EPS Algeciras, University of Cadiz, Avda. Ramon Puyol, s/n. 11202 Algeciras (Cadiz) (Spain); Garcia, Pablo, E-mail: pablo.garcia@uca.e [Department of Electrical Engineering, EPS Algeciras, University of Cadiz, Avda. Ramon Puyol, s/n. 11202 Algeciras (Cadiz) (Spain); Garcia, Carlos Andres, E-mail: carlosandres.garcia@uca.e [Department of Electrical Engineering, EPS Algeciras, University of Cadiz, Avda. Ramon Puyol, s/n. 11202 Algeciras (Cadiz) (Spain); Jurado, Francisco, E-mail: fjurado@ujaen.e [Department of Electrical Engineering, EPS Linares, University of Jaen, C/Alfonso X, No. 28. 23700 Linares (Jaen) (Spain)
2011-05-15
Research highlights: {yields} Hybrid electric power system for a real surface tramway. {yields} Hybrid system based on PEM fuel cell with dc/dc converter and Ni-MH battery. {yields} New control strategy for the energy management of the tramway. {yields} Hybrid system demonstrated to meet appropriate driving cycle of the tramway. -- Abstract: This paper presents a hybrid electric power system for a real surface tramway. The hybrid system consists of two electrical energy sources integrating a single dc/dc converter to provide the power demanded by the tramway loads (four electric traction motors and auxiliary services): (1) a Polymer Electrolyte Membrane (PEM) fuel cell (FC) as the primary and (2) a rechargeable Ni-MH battery as electrical energy storage to supplement the FC over the driving cycle. According to the requirements of the real driving cycle of the tramway, it was considered a 200 kW PEM FC system with two FCs connected in parallel and a 34 Ah Ni-MH battery. The PEM FC and Ni-MH battery models were designed from commercially available components. The power conditioning system provides the appropriate power for the tramway. It is composed of: (1) a unique dc/dc boot converter which adapts the FC output voltage to the 750 V traction standard dc bus; (2) three phase inverters to drive properly each electric motors; and (3) a braking chopper to dissipate excess of regenerative braking energy. Suitable state machine control architecture is presented for the hybrid system, its objective being to provide demanded power by the driving cycle, optimizing the energy generated. Following this objective, a new state machine control strategy based on eight states decides the operating point of each component of the system and a cascade control structure allows achieving the operating points determined by the strategy. Simulation results of the real driving cycle of the tramway check the adequacy of the hybrid electric power system.
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DEFF Research Database (Denmark)
Liu, Dong; Wang, Yanbo; Chen, Zhe
2017-01-01
The input capacitor's voltages are unbalanced under the conventional control strategy in a dual half-bridge cascaded three-level (TL) DC/DC converter, which would affect the high voltage stresses on the capacitors. This paper proposes a pulse-wide modulation (PWM) strategy with two working modes...... for the dual half-bridge cascaded TL DC/DC converter, which can realize the zero-voltage switching (ZVS). More significantly, a capacitor voltage balance control is proposed by alternating the two working modes of the proposed ZVS PWM strategy, which can eliminate the voltage unbalance on the four input...... capacitors. Therefore, the proposed control strategy can improve the converter's performances in: 1) reducing the switching losses and noises of the power switches; and 2) reducing the voltage stresses on the input capacitors. Finally, the simulation results are conducted to verify the proposed control...
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DC plasma arc melter technology for waste vitrification
International Nuclear Information System (INIS)
Hamilton, R.A.; Wittle, J.K.; Trescot, J.
1995-01-01
This paper describes the features and benefits of a breakthrough DC Arc Melter for the permanent treatment of all types of solid wastes including nonhazardous, hazardous and radioactive. This DC Arc Furnace system, now commercially available, is the low cost permanent solution for solid waste pollution prevention and remediation. Concern over the effective disposal of wastes generated by the industrial society, worldwide, has prompted development of technologies to address the problem. For the most part these technologies have resulted in niche solutions with limited application. The only solution that has the ability to process almost all wastes, and to recover/recycle metallic and inorganic matter, is the group of technologies known as melters. Melters have distinct advantages over traditional technologies such as incineration because melters operate at higher temperatures, are relatively unaffected by changes in the waste stream, produce a vitrified stable product, and have the capability to recover/recycle slag, metals and gas. The system, DC Plasma Arc Melter, has the lowest capital, maintenance and operating cost of any melter technology because of its patented DC Plasma Arc with graphite electrode. DC Plasma Arc Melter systems are commercially available in sizes from 50 kg/batch or 250--3,000 kg/hr on a continuous feed basis. This paper examines the design and operating benefits of a DC Plasma Arc Melter System
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Emittance compensation of CW DC-gun photoinjector
International Nuclear Information System (INIS)
Li Peng; Wu Dai; Xu Zhou; Li Ming; Yang Xingfan
2011-01-01
Emittance growth induced by space charge effect is very important, especially for CW DC-gun photoinjector. In this work, the linear space charge force and its effect on electron beam transverse emittance are studied, and the principle and properties of emittance compensation by solenoid are analyzed. The CAEP DC-gun photoinjector with a solenoid is also simulated by code Parmela. Simulated results indicate that the normalized transverse emittance of an 80 pC bunch at the 350 keV DC-gun ex-it is 5.14 mm · mrad. And after compensated by a solenoid, it becomes 1.27 mm · mrad. The emittance of beam is well compensated. (authors)
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DEFF Research Database (Denmark)
Pittini, Riccardo; Zhang, Zhe; Andersen, Michael A. E.
2013-01-01
Energy production from renewable energy sources is continuously varying, for this reason energy storage is becoming more and more important as the percentage of green energy increases. Newly developed fuel cells can operate in reverse mode as electrolyzer cells; therefore, they are becoming...... current. Dc-dc converter efficiency plays a fundamental role in the overall system efficiency since processed energy is always flowing through the converter; for this reason, loss analysis and optimization are a key component of the converter design. The paper presents an isolated full bridge boost dc...
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Integrated-Circuit Controller For Brushless dc Motor
Le, Dong Tuan
1994-01-01
Generic circuit performs commutation-logic and power-switching functions for control of brushless dc motor. Controller includes commutation-logic and associated control circuitry, power supply, and inverters containing power transistors. Major advantages of controller are size, weight, and power consumption can be made less than other brushless-dc-motor controllers.
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Research on DC Micro-grid system of photovoltaic power generation
Zheng, Yiming; Wang, Xiaohui
2018-01-01
The use of energy has become a topic of concern, the demand of people for power grows in number or quantity with the development of economy. It is necessary to consider using new forms of power supply-microgrid system for distributed power supply. The power supply mode can not only effectively solve the problem of excessive line loss in the large power grid, but also can increase the reliability of the power supply, and is economical and environmental friendly. With the increasing of DC loads, in order to improve the utilization efficiency, the DC microgrid power supply problems are begin to be researched and integrated with the renewable energy sources. This paper researched the development of microgrid, compared AC microgrid with DC microgrid, summarized the distribution of DC bus voltage level, the DC microgrid network form, the control mode and the main power electronics elements of DC microgrid of photovoltaic power generation system. Today, the DC microgrid system is still in the development stage without uniform voltage level standard, however, it will come into service in the future.