Influences of the trees plantation in structures of Santa Fe of Bogota

International Nuclear Information System (INIS)

Acuna, John Fabio

1999-01-01

Through the project - Evaluation of damages caused by forest species planted in Santa Fe of Bogota and of the publication: Lungs for Santa Fe de Bogota; the Agricultural Engineering Department of the National University of Colombia, in collaboration with the Botanical Garden of Bogota Jose Celestino Mutis, offers to the capital a valuable contribution on trees plantation and its influence on the structures. Keeping in mind that trees are vital for any city, because they constitute a relating a fundamental for the appropriate use of the senses because forms behave, scents, colors and natural flavors in a means where the rest of the landscape is artificial. They contribute with the health when purifying the air; with the ecology and environment because they are hosts of many other forms of life, they are source of beauty, recreation and harmony, also giving a stamp of identity to the city; however, their implantation and handle, demands knowledge and cares, to assure a harmonious and lasting integration with the city

Effect of socioeconomic status on the association between air pollution and mortality in Bogota, Colombia

Directory of Open Access Journals (Sweden)

Luis Camilo Blanco-Becerra

2014-07-01

Full Text Available Objective. To evaluate the modification effect of socioeconomic status (SES on the association between acute exposure to particulate matter less than 10 microns in aerodynamic diameter (PM10 and mortality in Bogota, Colombia. Materials and methods. A time-series ecological study was conducted (1998-2006. The localities of the cities were stratified using principal components analysis, creating three levels of aggregation that allowed for the evaluation of the impact of SES on the relationship between mortality and air pollution. Results. For all ages, the change in the mortality risk for all causes was 0.76% (95%CI 0.27-1.26 for SES I (low, 0.58% (95%CI 0.16-1.00 for SES II (mid and -0.29% (95%CI -1.16-0.57 for SES III (high per 10μg/m3 increment in the daily average of PM10 on day of death. Conclusions. The results suggest that SES significantly modifies the effect of environmental exposure to PM10 on mortality from all causes and respiratory causes.

Effects of an Educational Intervention on Breast Self-Examination, Breast Cancer Prevention-Related Knowledge, and Healthy Lifestyles in Scholars from a Low-Income Area in Bogota, Colombia.

Science.gov (United States)

Masso-Calderón, A M; Meneses-Echávez, J F; Correa-Bautista, J E; Tovar-Cifuentes, A; Alba-Ramírez, P A; Charry-Ángel, C E

2016-11-04

The aim of this study was to evaluate the effects of an educational intervention on breast self-examination, cancer prevention-related knowledge, practices, and behavior change in scholars from a low-income area in Bogota, Colombia. Uncontrolled trial was conducted in 155 scholars. Two educational sessions, 90 min each, were carried out in March 2015 according to the Colombian guidelines for educational communication in the framework of cancer control. All participants completed a self-reported questionnaire at pre- and post-intervention, as well as 1, 3, and 6 months after the intervention. Breast self-examination was practiced by 78.1% of the scholars, and the overall knowledge of breast cancer risk factors was poor. The educational intervention resulted in significant improvements on breast self-examination practice, the knowledge of the technique, and the knowledge of the main risk factors for breast cancer as well as the practice of physical activity and vegetable intake at 6 months follow-up. An educational intervention according to the Colombian guidelines for educational communication in the framework of cancer control improved the practice of breast self-examination, cancer prevention-related knowledge, as well as the practice of physical activity and vegetable consumption in scholars from a low-income area in Bogota, Colombia. Further randomized controlled studies are warranted.

Bio indication of water quality in the Bogota Sabane using fuzzy logic sagging and aquatic micro invertebrates

International Nuclear Information System (INIS)

Gutierrez, Juan David; Riss Wolfgang; Ospina Rodolfo

2002-01-01

An application of the Sagging-type fuzzy logic to calculate biological water quality in Bogota, Colombia is presented 28 sites corresponding to 9 watersheds in the Bogota area were used. The organisms selected were: Leptoceridae and Hidrobiosidae as indicators of clean waters, Planariidae and Amphipoda as indicators of polluted waters and Psychodida and Syrphidae as indicators of highly polluted waters Chironomids were also included. In order to prove the degree of reliability of Sugeno-type fuzzy logic, the results obtained were compared with values for the Cfq index, and a highly significant correlation was obtained

Young people in Bogota, Colombia develop their own strategies to prevent risky sexual behavior.

Science.gov (United States)

Saavedra, M

1996-01-01

Although the government of Colombia moved in 1993 to mandate sexuality education in primary and secondary schools, nongovernmental organizations have worked in this area for more than two decades. Notable has been the work of one such organization, the Colombian Human and Social Development Foundation, among youth from a marginal, underserved area of Bogota that houses approximately 27,000 adolescents. The project uses a peer approach to relate the values of responsibility, tolerance, and self-determination to the prevention of risky sexual behaviors. At the onset, 15 youth leaders from the local school identified strategies for raising the topic of sexuality to their peers: suggestion boxes, school radio programs, educational materials such as murals and pamphlets, workshops, board games with sexuality-related themes, and community involvement. Suggestion box submissions revealed that sixth and seventh graders wanted to know about puberty-related events, while older students were interested in the effects of masturbation on health and appearance and the association between premarital sexual activity and one's reputation. In an 18-month period, close to 9000 community residents were reached with program materials and 1798 adolescents participated in group meetings. Among the gains observed have been correction of misinformation, a broader view of sexuality, the capacity for independent thought, and self-pride.

History of the Oral and Maxillofacial Surgery Residency Program at Universidad el Bosque, Bogotá, Colombia.

Science.gov (United States)

Castro-Núñez, Jaime

2012-01-01

The formal training of oral and maxillofacial surgeons in Colombia started in 1958 at Hospital Sanjos6, thanks to the titanic work of Waldemar Wilhelm, a German-born surgeon who settled in BogotA in 1950. Today there are seven institutions in Colombia that offer residency programs in oral and maxillofacial surgery. The aim of this article is to describe the history of the Oral and Maxillofacial Surgery Residency Program at Universidad El Bosque in Bogota.

Plant succession patterns on residual open-pit gravel mines deposits Bogota

OpenAIRE

Ricardo A. Mora Goyes

1999-01-01

Based on both: the study of composition and structure of plant communities and the analysis of the physico-chemical characteristics of mining wastes, the initial patterns of primary succession were determined. These patterns were present in three deposits of waste material abandoned during 18, 36 and 120 months respectively. Sue materials were originated in open-pit gravel mines located to the south of Bogota (Colombia). This study pretends to contribute to the knowledge of the meehanlsms of ...

Where Latin Americans are physically active, and why does it matter? Findings from the IPEN-adult study in Bogota, Colombia; Cuernavaca, Mexico; and Curitiba, Brazil.

Science.gov (United States)

Salvo, Deborah; Sarmiento, Olga L; Reis, Rodrigo S; Hino, Adriano A F; Bolivar, Manuel A; Lemoine, Pablo D; Gonçalves, Priscilla B; Pratt, Michael

2017-10-01

Latin America (LA) has a unique structural, political, cultural and social environment. This study aimed to identify the places where Latin American adults are physically active; and to determine the association of using public- and restricted-access places with physical activity (PA). We used data from the International PA Environment Network study in Bogota, Colombia (n=1000, accelerometry=249); Cuernavaca, Mexico (n=677, accelerometry=652); and Curitiba, Brazil (n=697, accelerometry=331) (2010-2011). Walking and moderate-to-vigorous PA for leisure were measured with the International Physical Activity Questionnaire. Overall PA and PA within 10-minute bouts were measured with accelerometers. Participants reported use of public- and restricted-access places for PA. Mixed-effects regression models were used to determine the association of using public- and restricted-access places with PA. The streets were the most frequently-reported place for PA, and walking was the most common PA in the studied places. 'Informal', non-exercise-or-sports places (e.g., shopping malls) ranked high for use for PA in Bogota and Cuernavaca. In Curitiba, use of 'formal' places for sports/exercise (e.g., gyms) was more prevalent. Using public-access places was directly related to walking for leisure in all cities, and to additional PA outcomes in Bogota and Cuernavaca. In Cuernavaca and Curitiba, using restricted-access places was also associated with PA. Our study highlights the importance of public-access places for PA in LA. In some contexts, places for social interaction may be as important for PA as places for exercise/sport. Strategies increasing the availability, accessibility and quality of these places may effectively promote PA in LA. Copyright © 2016 Elsevier Inc. All rights reserved.

Molecular Epidemiology of Epidemic Severe Malaria Caused by Plasmodium vivax in the State of Amazonas, Brazil

Science.gov (United States)

2005-01-01

Suarez, C.F., Florez, C., del Portillo, H.A.; Andrade, L.E. Direct Submission to NCBI gene bank. Submitted 03-JAN-1997. Laboratorio de Biologia Molecular...Departamento de Biologia , Universidad Nacional de Colombia, Ciudad Universitaria, Santa Fe de Bogota, D.C., Colombia. Nardin, E.H.; Zavala, F

77 FR 14593 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Science.gov (United States)

2012-03-12

..., Orlando, c/o ALFA PHARMA S.A., Bogota, Colombia; c/o LABORATORIOS GENERICOS VETERINARIOS, Bogota, Colombia; c/ o LABORATORIOS KRESSFOR, Bogota, Colombia; c/o PENTA PHARMA DE COLOMBIA S.A., Bogota, Colombia.../o DISTRIBUIDORA DE DROGAS CONDOR LTDA., Bogota, Colombia; c/o ALFA PHARMA S.A., Bogota, Colombia; c...

Assessing the effect of physical activity classes in public spaces on leisure-time physical activity: "Al Ritmo de las Comunidades" A natural experiment in Bogota, Colombia.

Science.gov (United States)

Torres, Andrea; Díaz, María Paula; Hayat, Matthew J; Lyn, Rodney; Pratt, Michael; Salvo, Deborah; Sarmiento, Olga L

2017-10-01

The Recreovia program provides free physical activity (PA) classes in public spaces in Bogota, Colombia. The purpose of this study was to assess the effectiveness of the Recreovia program in increasing PA among users of nine parks in Bogota. This study was a natural experiment conducted between 2013 and 2015 in Bogota. Community members and park users living nearby three groups of parks were compared: Group 1 were parks implementing new Recreovias (n=3), Group 2 were control parks (n=3) without Recreovias, and Group 3 were parks with existing Recreovías. Individuals in the "intervention" group were exposed to newly implemented Recreovia programs in parks near their homes. Measurements were collected at baseline and 6-8months after the intervention started. A total of 1533 participants were enrolled in the study: 501 for the existing Recreovias (included in a cross-sectional assessment) and 1032 participants (from the new Recreovias and control parks) included in the cross-sectional and pre-post study. Most participants were low income females. Twenty-three percent of the intervention group started participating in the program. Users of existing Recreovias were significantly more active and less likely to be overweight/obese compared to new Recreovia users at baseline. No changes on PA were found when comparing the intervention and control groups. Recreovias may have potential for increasing PA at the population level in urban areas given their rapid scalability, the higher levels of PA observed among program users, and its potential to reach women, low-income, less educated populations, and the overweight and obese. Copyright © 2016 Elsevier Inc. All rights reserved.

[DIFFERENCES IN PHYSICAL ACTIVITY AND IN PHYSICAL CONDITION BETWEEN SCHOOL AGE STUDENTS OF TWO PUBLIC CURRICULUM PROGRAMS IN BOGOTA, COLOMBIA].

Science.gov (United States)

Carrillo Cubides, Raúl; Aldana Alarcón, Luis Gonzalo; Gutiérrez Galvis, Adriana Rocío

2015-11-01

During the past five decades there has been an increased in the prevalence of obesity and over weight, also in physical inactivity and /or low cardiorespiratory fitness within the population in school age from diverse regions of the planet, including Bogota-Colombia. The general objective of this study was to compare the physical condition and the levels of physical activity from students who belonged to two curriculum programs of the Public Schools Network from Bogota, one of which includes two sessions per week, each session of 90 minutes of physical activity. We developed a research of unlike cross-sectional groups. There were 178 children evaluated from the regular curriculum and 170 kids belonging to the program 40 x 40. The physical condition was evaluated applying the protocol of high priority from the ALPHA -Fitness test Battery. The weight, height, body mass index, the waist circumference, the standing long jump, the handgrip in both hands and the motor fitness 20 meter shuttle run test were developed under standardized conditions. The Global School Health Survey (GSHS) was used to evaluate the levels of AF. No significant statistical differences were founded between P-40x40 and the regular curriculum regarding: weight, height, the body mass index, the waist circumference, the handgrip in both hands and the explosive strength in lower limbs. Nevertheless the cardiorespiratory fitness was significantly lower within de P-40x40. In conclusion the participation in the curricular program 40 x 40 was not associated with better levels of physical condition. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

Personal dosimetry TLD 100 in orthopedic surgeons exposed to ionizing radiation in Bogota - Colombia; Dosimetria personal TLD 110 en medicos ortopedistas expuestos a radiacion ionizante en Bogota - Colombia

Energy Technology Data Exchange (ETDEWEB)

Sierra C, B. Y.; Jimenez, Y. [Universidad Nacional de Colombia, Departamento de Fisica, Grupo de Fisica Medica, Carrera 45 No. 26-85, Bogota (Colombia); Plazas, M. C. [Hospital Universitario Fundacion Santa Fe de Bogota, Instituto de Oncologia Carlos Ardila Lulle, Calle 119, No. 7-90, 220246 Bogota (Colombia); Eslava S, J. [Universidad Nacional de Colombia, Instituto de Investigaciones Clinicas, Grupo Equidad en Salud, Carrera 45 No. 26-85, Bogota (Colombia); Groot R, H., E-mail: brigith.sierra@gmail.com [Universidad de los Andes, Laboratorio de Genetica Humana, Carrera 1 No. 18A -12, Bogota (Colombia)

2014-08-15

Orthopedic surgeons should be considered as professionals occupationally exposed to ionizing radiation, for using C arc (fluoroscope) an equipment of X type radiation emission, during surgical procedures for imaging generation. Some health institutes, use of C arc under uncontrolled circumstances, such a lack of dosimetry control, incomplete or absence of personnel protective elements and protective measures, which in turn, lead to a high exposition to the personnel. Materials and methods. Study of double match cohort by age and gender, was conducted, in four health institutions of second and third level of attention in Bogota city. Personal dosimetry measurements with TLD-100 dosimetry crystals in both cohorts and environmental dosimetry in each of operation rooms used for orthopedic procedures, were carry out during six months of follow up. Dosimetry crystals were read in a Harshaw 4500 - Bicron equipment, in the Medical Physics Laboratory of National University of Colombia. Results. Dosimetry measurements are compatibles with those of occupationally exposed personnel 3.44 mSv/6 m CI 95% (1.66-3.99), even does not overpass ICRP recommendations, are higher as were expect at the beginning of the study. The median of effective accumulative dose in thorax is 3,4 mSv CI 95% (1,66-3,99), higher in comparison with neck value 2,7 mSv CI 95% (1,73-3,80) and hand dosimetry 1,42 mSv CI 95% (0,96-2,34). Conclusions: Orthopedic surgeons should be considered occupational exposed to ionizing radiation, who has to accomplish to the radiological protection measures, dosimetric follow up and maintenance of the used X ray equipment. It was confirm throughout this study that dosimetry shows higher levels as expected at the beginning of the study, compatible with occupationally exposed personnel. (Author)

Plant succession patterns on residual open-pit gravel mines deposits Bogota

Directory of Open Access Journals (Sweden)

Ricardo A. Mora Goyes

1999-07-01

Full Text Available Based on both: the study of composition and structure of plant communities and the analysis of the physico-chemical characteristics of mining wastes, the initial patterns of primary succession were determined. These patterns were present in three deposits of waste material abandoned during 18, 36 and 120 months respectively. Sue materials were originated in open-pit gravel mines located to the south of Bogota (Colombia. This study pretends to contribute to the knowledge of the meehanlsms of natural restauration of tropical ecosystems subjected to man-borne degradation.

All projects related to Colombia | Page 3 | IDRC - International ...

International Development Research Centre (IDRC) Digital Library (Canada)

Region: Argentina, Bolivia, Brazil, Colombia, Ecuador, Guatemala, Mexico, Peru, ... Violence in three Latin American cities: A comparative study between Bogota, Lima, ... Topic: Natural disasters, CLIMATOLOGY, Economic and social development, ... SOCIAL STRATIFICATION, CASE STUDIES, RESEARCH NETWORKS, ...

75 FR 65557 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Science.gov (United States)

2010-10-25

.../o PENTA PHARMA DE COLOMBIA S.A., Bogota, Colombia; c/o LABORATORIOS KRESSFOR DE COLOMBIA S.A... PHARMA DE COLOMBIA S.A., Bogota, Colombia; c/o DECAFARMA S.A., Bogota, Colombia; c/o DROCARD S.A., Bogota...) [SDNT]. 11. MORAN GUERRERO, Mario Fernando, c/o PENTACOOP LTDA., Bogota, Colombia; c/o PENTA PHARMA DE...

75 FR 54696 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Science.gov (United States)

2010-09-08

...., Bogota, Colombia; c/o DIRECCION COMERCIAL Y MARKETING CONSULTORIA EMPRESA UNIPERSONAL, Bogota, Colombia... COLOMBIA LTDA., Bogota, Colombia; c/o ASOCIACION TURISTICA INTERNACIONAL S.C.S., Bogota, Colombia; c/o...

[Profile of children and adolescents with autism spectrum disorders in an institution in Bogota, Colombia].

Science.gov (United States)

Talero-Gutiérrez, C; Rodríguez, M; De La Rosa, D; Morales, G; Vélez-Van-Meerbeke, A

2012-03-01

To determine the profile of children and adolescents diagnosed with autism spectrum disorder (ASD) in a comprehensive care centre in Bogota, Colombia. A descriptive-correlational study with a sample of patients who had attended the institution from 2003 to 2009. Demographic and clinical aspects were evaluated and a correlation between the diagnosis and severity being analysed in search for risk factors. A total of 138 patients were studied. The average age of onset was 21 months, and diagnosis had been made at 45 months. There was a male predominance (6.15:1). The predominant diagnosis was autistic syndrome (83%), followed by pervasive developmental disorder not otherwise specified (17%). There was no pathological background in the family history, during pregnancy or during the neonatal period. Motor development during the first year was normal but acquisition of language skills was compromised. The specific signs of ASD as regards the disorder in itself, communication skills, spontaneous speech, verbal comprehension, attention, imitation, use of objects, self-care and symbolic play were significantly related to the severity of the disease. Diagnosis of ASD is still delayed in our population and usually after referral from someone other than a health professional. The most important problems were found in communication skills and relationships with peers. The study did not show significant associated risk factors. Copyright © 2010 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.

75 FR 10557 - Additional Designations, Foreign Narcotics Kingpin Designation Act

Science.gov (United States)

2010-03-08

... BUSTOS ARIZA Y CIA. S.C.S., Bogota, Colombia; c/o MODERNA EXPRESS TRANSPORTE DE CARGA LTDA., Bogota..., Colombia; c/o LOGISTICA Y TRANSPORTE NORVAL LTDA., Bogota, Colombia; Calle 135 No. 17-25 apto. 503, Bogota.... LOGISTICA Y TRANSPORTE NORVAL LTDA., Avenida Boyaca No. 68-24, Bogota, Colombia; NIT 900224846-0 (Colombia...

Effect of particulate matter less than 10μm (PM10 on mortality in Bogota, Colombia: a time-series analysis, 1998-2006

Directory of Open Access Journals (Sweden)

Luis Camilo Blanco-Becerra

2014-07-01

Full Text Available Objective. To analyze the association between daily mortality from different causes and acute exposure to particulate matter less than 10 microns in aerodynamic diameter (PM10, in Bogota, Colombia. Materials and methods. A time-series ecological study was conducted from 1998 to 2006. The association between mortality (due to different causes and exposure was analyzed using single and distributed lag models and adjusting for potential confounders. Results. For all ages, the cumulative effect of acute mortality from all causes and respiratory causes increased 0.71% (95%CI 0.46-0.96 and 1.43% (95%CI 0.85-2.00, respectively, per 10μg/m3 increment in daily average PM10 with a lag of three days before death. Cumulative effect of mortality from cardiovascular causes was -0.03% (95%CI -0.49-0.44% with the same lag. Conclusions. The results suggest an association between an increase in PM10 concentrations and acute mortality from all causes and respiratory causes.

Awake at the wheel : Bogota's response to the transportation challenge

Energy Technology Data Exchange (ETDEWEB)

Diaz, O.E.

2001-03-01

The domination of private automobiles in cities like Bogota, Colombia, has resulted in vehicle chaos and increasingly high levels of atmospheric pollution that will poison urban populations. Eighty per cent of the people of Bogota ota use public transportation on a daily basis, but private vehicles occupy 95 per cent of the roads. Local authorities have indicated that the solution to the excessive use of the private automobile is to curtail its use. Bogota City Hall is working on developing the Bogota Project, a sustainable system of urban mobility which takes into account both supply and demand factors. The project includes the development of mass and alternative means of transportation such as the TransMilenio high-capacity mass transportation system consisting of articulated buses. By 2015, TransMilenio will have 22 lines and 6000 articulated buses. In addition, a network of cycle paths is being developed to encourage the use of bicycles as a means of transportation. The construction of sidewalks and shaded walks is also advancing throughout the city. Several measures are being implemented in order to stimulate the demand for public transportation and to restrict private car use. These include fees for public parking, increased gasoline taxes, and tolls at the city entrances. The peak and licence plate program is a measure that restricts 40 per cent of vehicles from travelling during peak hours in the entire urban area. Cycleway is a program which leaves the city's highways clear for 7 hours on Sundays for cycling, skating or walking. A referendum was held in October 2000 in which a proposal was put forward to restrict the use of private vehicles during the six hours of major traffic congestion beginning January 1, 2015. The 51 per cent support for the proposal means that no private vehicles, except taxis, will be allowed to circulate during rush hours. Sixty three per cent of the people of Bogota also supported the annual celebration of a car-free day on

The paleobotanical record of Colombia: Implications for biogeography and biodiversity

NARCIS (Netherlands)

Hooghiemstra, H.; Wijninga, V.M.; Cleef, A.M.

2006-01-01

Plant microfossil and macrofossil associations obtained from six dated sections from the area of the basin of Bogota¿ (2550 m, Eastern Cordillera, Colombia) show the evolution of the late Neogene Andean montane forest, triggered by the Andean orogeny. Progressive adaptation of warm tropical taxa to

Internal displacement in Colombia: Fifteen distinguishing features.

Science.gov (United States)

Shultz, James M; Ceballos, Ángela Milena Gómez; Espinel, Zelde; Oliveros, Sofia Rios; Fonseca, Maria Fernanda; Florez, Luis Jorge Hernandez

2014-01-01

This commentary aims to delineate the distinguishing features of conflict-induced internal displacement in the nation of Colombia, South America. Even as Colombia is currently implementing a spectrum of legal, social, economic, and health programs for "victims of armed conflict," with particular focus on internally displaced persons (IDPs), the dynamics of forced migration on a mass scale within this country are little known beyond national borders.   The authors of this commentary are embarking on a global mental health research program in Bogota, Colombia to define best practices for reaching the displaced population and implementing sustainable, evidence-based screening and intervention for common mental disorders. Presenting the defining characteristics of internal displacement in Colombia provides the context for our work and, more importantly, conveys the compelling and complex nature of this humanitarian crisis. We attempt to demonstrate Colombia's unique position within the global patterning of internal displacement.

Personal dosimetry TLD 100 in orthopedic surgeons exposed to ionizing radiation in Bogota - Colombia

International Nuclear Information System (INIS)

Sierra C, B. Y.; Jimenez, Y.; Plazas, M. C.; Eslava S, J.; Groot R, H.

2014-08-01

Orthopedic surgeons should be considered as professionals occupationally exposed to ionizing radiation, for using C arc (fluoroscope) an equipment of X type radiation emission, during surgical procedures for imaging generation. Some health institutes, use of C arc under uncontrolled circumstances, such a lack of dosimetry control, incomplete or absence of personnel protective elements and protective measures, which in turn, lead to a high exposition to the personnel. Materials and methods. Study of double match cohort by age and gender, was conducted, in four health institutions of second and third level of attention in Bogota city. Personal dosimetry measurements with TLD-100 dosimetry crystals in both cohorts and environmental dosimetry in each of operation rooms used for orthopedic procedures, were carry out during six months of follow up. Dosimetry crystals were read in a Harshaw 4500 - Bicron equipment, in the Medical Physics Laboratory of National University of Colombia. Results. Dosimetry measurements are compatibles with those of occupationally exposed personnel 3.44 mSv/6 m CI 95% (1.66-3.99), even does not overpass ICRP recommendations, are higher as were expect at the beginning of the study. The median of effective accumulative dose in thorax is 3,4 mSv CI 95% (1,66-3,99), higher in comparison with neck value 2,7 mSv CI 95% (1,73-3,80) and hand dosimetry 1,42 mSv CI 95% (0,96-2,34). Conclusions: Orthopedic surgeons should be considered occupational exposed to ionizing radiation, who has to accomplish to the radiological protection measures, dosimetric follow up and maintenance of the used X ray equipment. It was confirm throughout this study that dosimetry shows higher levels as expected at the beginning of the study, compatible with occupationally exposed personnel. (Author)

Latin American Clinical Epidemiology Network Series - Paper 6: The influence of alcohol in traffic accidents and health care costs of it in Bogotá-Colombia.

Science.gov (United States)

Gómez-Restrepo, Carlos; Naranjo-Lujan, Salomé; Rondón, Martín; Acosta, Andrés; Maldonado, Patricia; Arango Villegas, Carlos; Hurtado, Jaime; Hernández, Juan Carlos; Angarita, María Del Pilar; Peña, Marcela; Saavedra, Miguel Ángel; Quitian, Hoover

2017-06-01

In Colombia, some studies have estimated medical costs associated to traffic accidents. It is required to assess results by city or region and determine the influence of variables such as alcohol consumption. The main objective of this study was to identify health care costs associated to traffic accidents in Bogota and determine whether alcohol consumption can increase them. Cross-sectional costs study conducted in patients over 18 years treated in the emergency rooms of six different hospitals in Bogota, Colombia. The average total cost of medical care per patient was 628 USD, in Bogota-Colombia. The average cost per accident was estimated at 1,349 USD. On average, the total cost for health care for patients with positive blood alcohol level was 1.8 times higher than those who did not consume alcohol. The indirect costs were on average 115.3 USD per injured person. Numbers are expressed in 2011 U.S. dollars. Alcohol consumption increases the risk of traffic accidents and direct medical health costs. Copyright © 2016 Elsevier Inc. All rights reserved.

77 FR 41479 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Science.gov (United States)

2012-07-13

..., Maria Teresa), c/o INVERSIONES MPS S.A., Bogota, Colombia; c/o PROYECTOS Y SOLUCIONES INMOBILIARIA LTDA., Bogota, Colombia; c/o GERENCIA DE PROYECTOS Y SOLUCIONES LTDA., Bogota, Colombia; DOB 3 Aug 1957; POB...

Guerrilla Violence in Colombia: Examining Causes and Consequences

Science.gov (United States)

1994-06-01

Ecuador’s Alfaro 27 Walker, Phyllis, "National Security", in Colombia a Country Study, Washington, 1990, p. 300. 28 Registraduria Nacional del Estado Civil...necessary to profoundly transform institutions. On several occasions, the old political 114 Informe Financiero Contraloria General de la Rep~blica, June...Societies, Princeton Press, 1988. Informe Financiero Contraloria General de la Repzblica, Bogota, 1988. Kalmanovitz, Salomon, Economia del

Normative reference values for the 20 m shuttle‐run test in a population‐based sample of school‐aged youth in Bogota, Colombia: the FUPRECOL study

Science.gov (United States)

Palacios‐López, Adalberto; Humberto Prieto‐Benavides, Daniel; Enrique Correa‐Bautista, Jorge; Izquierdo, Mikel; Alonso‐Martínez, Alicia; Lobelo, Felipe

2016-01-01

Abstract Objectives Our aim was to determine the normative reference values of cardiorespiratory fitness (CRF) and to establish the proportion of subjects with low CRF suggestive of future cardio‐metabolic risk. Methods A total of 7244 children and adolescents attending public schools in Bogota, Colombia (55.7% girls; age range of 9–17.9 years) participated in this study. We expressed CRF performance as the nearest stage (minute) completed and the estimated peak oxygen consumption (V˙O2peak). Smoothed percentile curves were calculated. In addition, we present the prevalence of low CRF after applying a correction factor to account for the impact of Bogota's altitude (2625 m over sea level) on CRF assessment, and we calculated the number of participants who fell below health‐related FITNESSGRAM cut‐points for low CRF. Results Shuttles and V˙O2peak were higher in boys than in girls in all age groups. In boys, there were higher levels of performance with increasing age, with most gains between the ages of 13 and 17. The proportion of subjects with a low CRF, suggestive of future cardio‐metabolic risk (health risk FITNESSGRAM category) was 31.5% (28.2% for boys and 34.1% for girls; X2 P = .001). After applying a 1.11 altitude correction factor, the overall prevalence of low CRF was 11.5% (9.6% for boys and 13.1% for girls; X2 P = .001). Conclusions Our results provide sex‐ and age‐specific normative reference standards for the 20 m shuttle‐run test and estimated V˙O2peak values in a large, population‐based sample of schoolchildren from a large Latin‐American city at high altitude. PMID:27500986

78 FR 47492 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Science.gov (United States)

2013-08-05

... PROYECTOS Y SOLUCIONES S.A., Bogota, Colombia; c/ o PROYECTOS Y SOLUCIONES INMOBILIARIA LTDA., Bogota, Colombia; c/o GERENCIA DE PROYECTOS Y SOLUCIONES LTDA., Bogota, Colombia; c/o ACUICOLA SANTA CATALINA S.A...; NIT 805027303-4 (Colombia) [SDNT]. 7. PROYECTOS J.A.M. LTDA. Y CIA. S. EN C., Calle 74 No. 53-23 of...

Uso de hierbas medicinales en mujeres gestantes y en lactancia en un hospital universitario de Bogotá (Colombia The use of herbal medicine among pregnant and lactating women attending a university hospital in Bogota, Colombia

Directory of Open Access Journals (Sweden)

Gloria Paulina Pulido Acuña

2012-12-01

Full Text Available Las mujeres durante la gestación y lactancia utilizan diferentes hierbas y es escasa la información en el ámbito clínico en Colombia. Objetivo: Describir las prácticas relacionadas con el uso de hierbas en mujeres gestantes y en lactancia del Hospital de San José, Bogotá (Colombia. Metodología: Estudio de corte transversal. Con un cuestionario estructurado se indagó el uso, la frecuencia, el modo y razones de uso, de las hierbas medicinales y de quién se aprendió la práctica. Resultados: El uso de hierbas en mujeres gestantes y en lactancia fue de 33.6% (IC95%: 29.2% - 38% y 36.6% (IC95%: 30.8% - 42.3%, respectivamente. En el grupo de gestantes la hierba más usada fue la manzanilla (36.7% y en las mujeres en lactancia fue el hinojo (65%. Conclusión: Las mujeres gestantes y en lactancia, utilizan hierbas para las molestias del embarazo, acelerar el parto, disminuir el frío y promover la producción de leche.The use of herbal supplements is a common practice about pregnant and lactating women, however in Colombia there is limited data regarding the extent of women's use of herbal medicines during pregnancy and breastfeeding. The aim of this study was to describe the patterns of herbal medication use among pregnant and lactating women at the Hospital San Jose in Bogota, Colombia. Methods: Cross-sectional study. A questionnaire was designed to measure the frequency of herbal supplementation, why women took the herbal medicine, form of supplements, and who recommended the supplements or how did they learn about the herbal supplements. Results: The use of herbal supplements among pregnant and lactating women is 33.6% (CI 95%: 29.2%-38% and 36.6 (CI 95%: 30.8%-42.3%, respectively. The most common supplement used by pregnant women is Chamomile (36,7%, and among lactating women is Fennel (Foeniculum vulgare (65%. Conclusion: Pregnant and breastfeeding women use herbal supplements for specific pregnancy-related problems, to induce labor, to

History of medical micology in Colombia, 1930-1970 = Historia de la micología médica en Colombia, 1930-1970

OpenAIRE

Galvis Pérez, Yeisson; Cano Restrepo, Luz Elena; Vásquez Valencia, María Fernanda

2013-01-01

The overall objective of this research was to understand the events that made possible the creation, diffusion and appropriation of medical mycology in Colombia between 1930 and 1970. It was based on the review of scientific journals and theses in different libraries, archives and documentation centers in Medellin and Bogota. The report includes the different problems faced by physicians and laboratory personnel concerning the classification of fungi, the relationship between dermatology and ...

The biodiversity from Bogota

International Nuclear Information System (INIS)

Calvachi Zambrano, Byron

2002-01-01

It is about the flora biodiversity and fauna that it occupied the savannah of Bogota originally, about the flora and extinct fauna and of the flora and fauna that still persist in spite of the colonization

Air Pollution alongside Bike-Paths in Bogota - Colombia

Directory of Open Access Journals (Sweden)

Juan Felipe Franco

2016-11-01

Full Text Available The study we present in this paper aims at characterizing the range of fine particulate matter (PM2.5 and black carbon (BC concentrations to which bike-path users in Bogotá are exposed to. Using a bike equipped with a DustTrak and a micro-aethalometer we measured PM2.5 and BC concentration levels along bike-paths corridors, during weekdays and weekends. Experiments were conducted in fours streets, representing four typical configurations of bike-paths in the city. Traffic data for workdays was also available from local mobility authority. Results indicate that bike-paths users in Bogota are exposed to air pollution levels far exceeding the threshold values established as potentially dangerous for human health. Average concentrations for PM2.5 ranged between 80 and 136 ug/m3 in workdays and between 30 and 72 ug/m3 in weekends. BC mean concentrations were between 16 and 38 µg/m3 during workdays and in the range 10 to 32 µg/m3 during weekends. A statistically significant difference exists in the levels of pollutants concentrations measured during workdays and weekends for all the considered bike paths. According to our results, both traffic volume and diffusions conditions, which are affected by many factors including street geometry, affect bike-path user’s exposure levels. Taking into account the important role that bicycling is playing as an alternative transport mode in Latin American cities, we consider these results provide useful insights to increase the appreciation of the excessive bikers´ exposure to air pollution in Bogotá. Moreover, these findings contribute with technical elements that should lead to the inclusion of air quality variable when designing and planning sustainable urban mobility infrastructures.

Colombia: Emerging Labor Movement and the State Colombian Drug Problem: Effect on the Peace Process between the M19 and the State

Science.gov (United States)

1990-05-01

de la Energia en Colombia. 1537-1930 (Bogota,1985), 1. 39 Steam navigation in the inland rivers, Magdalena and Cauca Rivers, used wood as a fuel to...Cartagena, 325. 72 Table 5. Cartagena-Oil Refining Co. 1912 Prod Rates (Monthly) ° Product Octane Amount Gasoline 72 Kerosene "Luz Solar " 110 Kerosene "Luz...1987. De La Pedraja, Ren6. Energy Politics in Colombia, San Francisco : Westview Press, 1989. De La Pedraja, Ren6. Historia de la Energia en Colombia

Terrorism in Colombia.

Science.gov (United States)

Paredes Zapata, Gabriel Darío

2003-01-01

Colombia is a poor country that has been plagued by ongoing violence for more than 120 years. During the 1940s, subversive terrorist groups emerged in rural areas of the country when criminal groups came under the influence of Communism, and were later transformed into contemporary groups, such as the Ejercito de Liberacion Nacional (ELN) or National Liberation Army and Fuerzas Armadas Revolucionares de Colombia (FARC) or Revolutionary Armed Forces of Colombia). Paramilitary terrorist groups emerged in response to subversive groups and were later transformed into contemporary groups, such as the Autodefensas Unidas de Colombia (AUC) or United Self-Defense Forces of Colombia. Terrorism has placed an enormous burden on modern Colombia. From 1995 to 2002, 9,435 people were killed by terrorism-related events, of which 5,864 were killed by subversive terrorist activities and 3,571 were killed by paramilitary terrorist activities. In 2002, at least nineteen attacks produced 10 or more casualties, of which 18 were bombings. In 2002, terrorists killed at least 12 mayors, 71 legislators, and internally displaced 300,000 persons from their homes. Since terrorist groups in Colombia are typically supported by drug manufacturing and trafficking, it has been difficult at times to distinguish violence due to terrorism from violence due to illicit drug trafficking. Terrorism has also had a major adverse effect on the economy, with restricted travel, loss of economic resources, and lack of economic investment. In addition to political, military, and commercial targets, terrorists have specifically targeted healthcare infrastructure and personnel. At the national and local levels, much emergency planning and preparedness has taken place for terrorism-related events. The Centro Regulador de Urgencias (CRU) or Emergency Regulation Center in Bogota plays a major role in coordinating local prehospital and hospital emergency response in the capital city and the national level where

Role of sleep duration and sleep-related problems in the metabolic syndrome among children and adolescents

OpenAIRE

Pulido-Arjona, Leonardo; Correa-Bautista, Jorge Enrique; Agostinis-Sobrinho, Cesar; Mota, Jorge; Santos, Rute; Correa-Rodríguez, María; Garcia-Hermoso, Antonio; Ramírez-Vélez, Robinson

2018-01-01

Background There is increasing recognition that sleep is a risk factor for metabolic syndrome (MetS). The aim of the present study was to analyze the relationship between self-reported sleep duration, sleep-related problems and the presence of MetS in children and adolescents from Bogotá, D.C., Colombia. Methods This is a cross-sectional analysis from the FUPRECOL study (2014–15). Participants included 2779 (54.2% girls) youth from Bogota (Colombia). MetS was defined as the presence of ≥3 of ...

Bogota bag in the treatment of abdominal wound dehiscence.

Science.gov (United States)

Sukumar, N; Shaharin, S; Razman, J; Jasmi, A Y

2004-06-01

A patient who underwent emergency laparotomy for rectal prolapse developed repeated abdominal wound dehiscence and subsequently an enteric fistula. The management of abdominal wound dehiscence is discussed, specifically with regards to the Bogota bag. Use of Bogota bag has been reported worldwide but this may be the first report here.

78 FR 62947 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Foreign...

Science.gov (United States)

2013-10-22

...., Bogota, Colombia; c/o FERTILIZANTES LIQUIDOS DE LA SABANA LTDA., Bogota, Colombia; Calle 109 No. 21-41... 800099351-8 (Colombia) [SDNTK]. 3. FERTILIZANTES LIQUIDOS DE LA SABANA LTDA. (a.k.a. FERTILISA LTDA.), Calle...

77 FR 63420 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Science.gov (United States)

2012-10-16

...., Bogota, Colombia; c/o DROGAS LA REBAJA, Cali, Colombia; c/o VALORES MOBILIARIOS DE OCCIDENTE S.A., Bogota... VARIOS CALIMA S.A., Cali, Colombia; c/o CHAMARTIN S.A., Cali, Colombia; c/o SERVICIOS DE LA SABANA E.U... VALLE S.A., Cali, Colombia; c/o CONCRETOS CALI S.A., Cali, Colombia; c/o ADMINISTRACION INMOBILIARIA...

76 FR 11561 - Additional Designations, Foreign Narcotics Kingpin Designation Act

Science.gov (United States)

2011-03-02

....A., Cali, Colombia; c/o INVERSIONES CIFUENTES Y CIA. S. EN C., Medellin, Colombia; c/o PARQUES... Federal, Mexico; c/o LINEA AEREA PUEBLOS AMAZONICOS S.A.S., Bogota, Colombia; c/o PARQUES TEMATICOS S.A... HOTELES Y BIENES S.A., Bogota, Colombia; c/o INVERPUNTO DEL VALLE S.A., Cali, Colombia; c/o PARQUES...

Male-only clinics: a success story in Colombia.

Science.gov (United States)

Goldman, R

1987-04-01

2 male-only reproductive health clinics in Colombia are refuting the stereotype that Latin American men reject vasectomy as a threat to their machismo image and consider birth control to be a woman's responsibility. Over 1000 vasectomies were performed in the 2 clinics in Bogota and Medellin in 1986. The clinics are operated by PROFAMILIA and supported by the Association for Voluntary Surgical Contraception. Information about these male-only clinics is dispersed through radio announcements, magazine advertisements, and newspaper articles. The cost of services at these clinics is 50% less than services provided at other family facilities. These clinics demonstrate that Colombian men are willing to share family planning responsibilities if services are offered in a manner respectful of their needs. 3 additional male-only clinics are scheduled to open in Colombia in 1987.

A new case of alert about a possible menace to native fauna of amphibians in Colombia: first report of the bull frog (Lithobates catesbeianus) in the savanna of Bogota

International Nuclear Information System (INIS)

Mueses Cisneros, Jhon Jairo; Ballen, Gustavo

2007-01-01

Two specimens of bullfrog (Lithobates catesbeianus) in two different localities of Bogota are reported. Knowing the devastating effect that this species produces to the native populations of amphibians where it is introduced, we warn of the possible danger that the species of amphibians of the sabana of Bogota can suffer if no controls on the management and trade of this species are done

Effect of size and vegetation cover in urban parks in the richness and diversity of bird life in Bogota, Colombia

International Nuclear Information System (INIS)

Berget, Carolina

2006-01-01

In one section of Bogota city some characteristics of urban recreational areas (size, distance to the east hills, coverage and diversity of vegetation) and their effects over the bird fauna diversity were studied between April and June of 2004. The samplings were made in 18 recreational areas of different sizes (100 m2 1 300000 m2), and at different distances (1.40 km -7.0 km) from two native vegetation patches to the east hills in Bogota, which were thought to be habitat sources. Lineal regression analysis showed that bird fauna diversity is affected by the size of the recreational area and, to a lesser extent, the vegetation cover, but not by other variables. These recreational areas are not considered fragments but human made islands and, therefore, they do not contain many relict forest bird species. I concluded that the east hills are not source habitat of bird species for the urban recreational areas studied. These habitats are suitable for the establishment of species associated to open areas

[Prostitution and poverty in Santafe de Bogota].

Science.gov (United States)

Cabrera Fadul, O

1998-06-01

The Chamber of Commerce of Bogota conducted a study of prostitution in the city with the participation of prostitutes themselves. In 1990, around 14,000 women were found to be working as prostitutes in the city's center, with 44% concentrated in the barrios of La Alameda, Las Nieves, and San Bernardo. Over 70% of the women were born outside of Bogota. 82% were aged 15-40 years; the age range was 9-60 years. 1200 minors were counted. A 1992 study in the sector of Chapinero revealed 3480 women working as prostitutes. 81% had migrated to the city and 96% were aged 15-40 years. Visible street prostitution was infrequent. A 1993 study of child prostitution in a smaller area than the 1990 center-city study revealed 2959 minors, suggesting that the number had nearly tripled. 60% were natives of the city. A 1994 study of 200 male prostitutes in the center-city found that 24% were natives of Bogota. 32% had left home before the age of 10. 89% had become prostitutes before their 16th birthday. 17% were HIV-seropositive; most of their clients were married men. In all cases, the factors leading to prostitution originated within the family and included physical mistreatment, sexual abuse by parents or stepparents, rejection and abandonment, as well as lack of income, unemployment, and lack of skills. Information on HIV infection was incomplete and ineffective. The number of indigent and homeless persons and that of drug addicts living on the streets of Bogota is not known. A large number of governmental and nongovernmental organizations attempt to provide help, but their efforts are not guided by any coherent plan of action.

Description of the early stages of Eccopsis galapagana Razowski & Landry (Lepidoptera: Tortricidae), a defoliator of Prosopis juliflora (Sw.) DC (Fabaceae) in Colombia

Science.gov (United States)

The biology and early stages of Eccopsis galapagana Razowski & Landry are described and illustrated for the first time; details of the adults also are provided. Under outbreak conditions, the species has become a serious pest of algarrobo tree (Prosopis juliflora (Sw.) DC.; Fabaceae) in Colombia. Al...

History of medical micology in Colombia, 1930-1970 = Historia de la micología médica en Colombia, 1930-1970

Directory of Open Access Journals (Sweden)

Galvis Pérez, Yeisson

2013-04-01

Full Text Available The overall objective of this research was to understand the events that made possible the creation, diffusion and appropriation of medical mycology in Colombia between 1930 and 1970. It was based on the review of scientific journals and theses in different libraries, archives and documentation centers in Medellin and Bogota. The report includes the different problems faced by physicians and laboratory personnel concerning the classification of fungi, the relationship between dermatology and mycology, the development of the study of systemic mycoses and the role played by some persons in the institutionalization of medical mycology.

Findings on education in Bogota (Colombia based on a 2014 multipurpose survey

Directory of Open Access Journals (Sweden)

Sandra Patricia Barragán Moreno

2017-06-01

Full Text Available This paper presents a study on education of the Multipurpose Survey of the year 2014, financed by the District Department of Planning of the city of Bogotá and developed by the National Statistics Department. This study focuses on determining the main reasons why people of school age did not do so at the time of the survey, and in characterizing the educational levels of household heads and their spouses or partners as referring adults in the households surveyed. The survey was applied to a sample of 61,725 people, who according to the sample design represent 7,794,463 inhabitants of urban areas in Bogota. Using descriptive and data mining techniques, it is stated that the two main reasons for not studying are the lack of money and the need to work. In addition, marital status is a more determinant predictor than sex or socioeconomic stratum. Single people are motivated to earn a college degree when they have had access to higher education at some point in their life. When studying the information of household heads, a similar behavior was observed, because the reasons for not studying were practically the same. Unplanned pregnancy and living with a partner are not outstanding reasons.

Study of groundwater in the Chicu River basin, Sabana de Bogota, Colombia; Estudio de las aguas subterraneas de la cuenca del Rio Chicu, Sabana de Bogota, Colombia

Energy Technology Data Exchange (ETDEWEB)

Obando G, E; Jimenez B, G; Torres Q, E; Alayon C, E; Garavito B, F [Instituto de Ciencias Nucleares y Energias Alternativas, INEA, Bogota (Colombia)

1995-10-01

The Rio Chicu Valley aquifer system represents one of the many sub-systems constituting the hydrogeological system of the Sabana de Bogota. The valley has a structure of a graben, covered by a quaternary alluvial formation, which has a low permeability and therefore is an aquifer of poor characteristics. Due to the thickness of this aquifer (around 300 m), the tertiary aquifers are only exploited by few deep wells. The isotopic composition of water collected from the tertiary aquifer is depleted by 1 per mille in {delta}{sup 18}O and 8 per mille in {delta}D. This difference is due to the altitude effect of recharge, because the tertiary aquifers outcrop on the top of the surrounding hills. In some places, the stable isotope content of water sampled in wells tapping water from the quaternary aquifer is similar to the values found in the tertiary aquifer. This fact indicates the ascending leakage from deep horizons. A rather unique characteristics of the quaternary aquifer is that in the central part of the basin the dissolved inorganic carbon DIC is very high and shows a {delta}{sup 13}C values around +10 per mille vs PDB and {sup 14}C around 5-10 pmc. The positive values are probably related to decomposition of organic matter in anaerobic conditions. These values reflect a very low flow in the system and limited recharge. (author). 1 ref., 5 figs, 2 tabs.

?Strange Attractors (chaos) in the hydro-climatology of Colombia?

International Nuclear Information System (INIS)

Poveda Jaramillo, German

1997-01-01

Inter annual hydro-climatology of Colombia is strongly influenced by extreme phases of ENSO, a phenomenon exhibiting many features of chaotic non-linear system. The possible chaotic nature of Colombian hydrology is examined by using time series of monthly precipitation at Bogota (1866-1992) and Medellin (1908-1995), and average stream flows of the Magdalena River at Puerto Berrio. The power spectrum, the Haussdorf-Besikovich (fractal) dimension, the correlation dimension, and the largest Lyapunov exponent are estimated for the time series. Ideas of hydrologic forecasting and predictability are discussed in the context of nonlinear dynamical systems exhibit chaotic behavior

Nuclear Medicine week in Colombia

International Nuclear Information System (INIS)

Padhy, A.K.

2003-01-01

During the week of 6-12 October 2003 the IAEA organized a Research Coordination Meeting on 'Relationship between lower Respiratory Tract Infection, Gastroesophageal reflux and bronchial Asthma in children' at Hospital San Ignacio in Bogota. Besides there were four workshops in Bogota; workshops on Bone infection and Bone scan in Pediatric ortopaedics at Hospital Militar and Fundacion CardioInfantil, a workshop for Nuclear Medicine Technologists and a workshop on Sentinel Lymph Node mapping and Surgical Gamma Probe Application at Institute of Oncology. A nuclear cardiology workshop was organized in Medellin, and finally crowning them all was the 9th Congress of the Colombian Association of Nuclear Medicine at Cali from 10-12 October, 2003; probably the largest and best Colombian nuclear medicine congress every held in the country. A workshop was also organized in Cali for nuclear medicine technologists in conjunction with the Annual Convention. It was a mix of IAEA's Technical Cooperation and Regular Budget activities along with the activities of Colombian Association of Nuclear Medicine, bringing in absolute synergy to galvanize the entire nuclear medicine community of the country. The week saw nuclear medicine scientists from more than 20 IAEA Member States converging on Colombia to spread the message of nuclear medicine, share knowledge and to foster International understanding and friendship among the nuclear medicine people of the world

Use of spermicide and impact of prophylactic condom use among sex workers in Santa Fe de Bogota, Colombia.

Science.gov (United States)

Farr, G; Acosta Castro, L A; DiSantostefano, R; Claassen, E; Olguin, F

1996-01-01

Condom use is one of the most important preventive measures sex workers can take to reduce the risk of becoming infected with a sexually transmitted disease. However, a client may refuse to use a condom when requested. Some sexually transmitted disease prevention programs are recommending that sex workers use spermicide as an alternative prophylaxis when a condom is refused, yet little is known about the effect of this recommendation on prophylactic condom use. To determine if using spermicide, either in conjunction with condoms or as a backup, influenced overall condom use among a group of sex workers at high risk of sexually transmitted diseases in Santa Fe de Bogota, Colombia. Participants were assigned randomly to one of three condom use groups: use of condoms only (Condoms Only), use of condoms and spermicides concurrently (Condom and Spermicide), or use of spermicide when condoms were refused (Spermicide as a Backup). A total of 199 sex workers entered the study and were asked to return for follow-up every 2 weeks for a period of 12 weeks. Women assigned to the Spermicide as a Backup group used a condom for an average of 78.1% of their reported acts of intercourse, compared with an average of 94.5% in the Condom Only and 92.3% in the Condom and Spermicide groups. However, women in the Spermicide as a Backup group used a condom or spermicide for an average of 96.9% of their acts of intercourse. Condoms were used for every intercourse act by less than 5% of the women in the Spermicide as a Backup groups, compared with 50.7% in the Condom Only group and 41.2% in the Condom and Spermicide group (P 0.001). When condoms were not used, client refusal was the primary reason reported. The incidence of sexually transmitted diseases and other urogenital inflammations in all groups was lower than expected. Among Colombian sex workers, condom use declined substantially when women were instructed to use spermicides if they were unable to persuade their partner to use a

Highlights from the first ecancer-Liga Colombiana contra el Cancer conference, 17-18 November 2016, Bogota, Colombia.

Science.gov (United States)

Castro, Carlos

2017-01-01

The first oncology conference organised by e cancer and the Liga Colombiana contra el Cancer took place on 17-18 November 2016 in Bogota. It was a highly successful event owing to the number of participants, the quality of the speakers, and the academic programme. Around 48 professors from 8 different countries came and shared their knowledge and experience of cancer management. They also talked about the most recent developments noted or achieved in this area. The keynote speech from Dr Nubia Muñoz was of great interest which was related to the safety of a HPV vaccine and the implications of a mass vaccination programme in developing countries. Geriatric oncology and palliative care were also topics that sparked great interest during the event.

76 FR 25149 - Endangered and Threatened Wildlife and Plants; Annual Notice of Findings on Resubmitted Petitions...

Science.gov (United States)

2011-05-03

... Bolivia, Peru. curassow. C 2 Rallus semiplumbeus Rallidae Bogota rail........ Colombia. C 8 Porphyrio... = 2 The Bogota rail is found in the East Andes of Colombia on the Ubat[eacute]-Bogot[aacute] Plateau... (shallow-rimmed depressions in soil or vegetation) are usually on sandy beaches just above spring-tide and...

Contribución al conocimiento de los Machiloidea de Colombia (Archaeognatha: Insecta Contribución al conocimiento de los Machiloidea de Colombia (Archaeognatha: Insecta

Directory of Open Access Journals (Sweden)

Sturm Helmut

1983-09-01

Full Text Available Se describen cuatro nuevas especies y una subespecie de Meinertellidae recolectadas en Colombia y en un bosque pluvial cerca de Manaos, Brasil. Son las siguientes: Meinertellus adisi, M. bogotensis santaemartae, Neomachilellus aboucbaari, N. amazonicus y N. rangeli. Se discute la posición sistemática de los ejemplares recolectados cerca de Bogotá, en el valle del río Magdalena y en la Cordillera Oriental cerca de Neiva. Se da una clave para los géneros suramericanos de la familia.Four new species and one new subspecies of Meinertellidae occurring respectively in Colombia and in the rain forest near Manaus, Brazil, are described:  Meinertellus adisi, M. bogotensis santaemartae , Neomachilellus abouchaari, N. amazonicus and N. rangeli. The systematical position of specimens collected near Bogota, in the Magdalena Valley and in the Eastern Andes near Neiva is discussed. A key for the South American genera of the family is given.

Colombia: A Country Under Constant Threat of Disasters

Science.gov (United States)

2014-05-22

Hydrological Map Source: El Clima Colombiano, “El Clima Colombiano, Ciclo Anual de Lluvias,” http://pwp.supercabletv.net.co/garcru/colombia/Colombia...a Global Risk Analysis. Washington, DC: World Bank Publications, 2005. El Clima Colombiano. “El Clima Colombiano, Ciclo Anual de Lluvias.” http

Assessment of environmental projects in official schools in the locality 18 in Bogota

International Nuclear Information System (INIS)

Herrera R, Juan Francisco; Reyes S, Lucia; Amaya, Hector Oswaldo T .Gerena Oscar Arturo

2006-01-01

It was investigated the current state of de School Environment Projects in the public educational institutions of de Town 18 Rafael Uribe Uribe in Bogota (Colombia). The participation grade was measured in the design o execution and evaluation of the environmental projects, the registration and systematising of experiences, the generation of reflection spaces and the structuring to the Institutional Educational Project. By means of the test pilot the variables were determined for the sample design and the validation of the mensuration instrument. Three populations study object were determined and for each was designed a for through which the information of the variable was gathered by means of the method of direct interview. The results show that the overwhelming majority of the considered population didn't participated in the design in the execution of the environmental projects. The registration and systematizing of experiences are minimum, as well as the reflection spaces and conceptualization. There is not articulation from the environmental project to the Institutional Educational Project. The little participation, systematizing of experiences and lack of reflection spaces and conceptualization limit the impact of the School Environmental Projects in the formation of favorable attitudes to the environment

77 FR 25536 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Science.gov (United States)

2012-04-30

... (Colombia) (individual) [SDNT]. 6. RODRIGUEZ CONRADO, Elmer Martin, c/o COPSERVIR LTDA., Bogota, Colombia; c... MIGUEL RODRIGUEZ E HIJO, Cali, Colombia; c/o RADIO UNIDAS FM S.A., Cali, Colombia; c/o REVISTA DEL...

77 FR 74918 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Science.gov (United States)

2012-12-18

... Ofc. 702, Cali, Colombia; c/o PARQUE INDUSTRIAL PROGRESO S.A., Yumbo, Colombia; c/o CIA. MINERA DAPA S... PARQUE INDUSTRIAL PROGRESO S.A., Yumbo, Colombia; c/o CIA. MINERA DAPA S.A., Bogota, Colombia; c/o...

The Pact of Bogota: Cases and Practice

Directory of Open Access Journals (Sweden)

María Teresa Infante Caffi

2017-03-01

Full Text Available The jurisdiction of the International Court of Justice (ICJ under the Pact of Bogota (1948 is part of a system of norms attributing competenceto the referenced tribunal along with other means of settlement. The system sets out principles and general exceptions applicable to all the means of peaceful settlement embodied in the Pact. This study will topic relates to the theory of dispute settlement and treaty interpretation hemispheric politics and diplomacy.

Contamination with Cadmium and Arsenic in soils and vegetables of a sector of the Bogota River Basin

International Nuclear Information System (INIS)

Gonzalez G, Saul; Mejia, Leonidas

1995-01-01

Soils of six different horticultural sites of the Savanna of Bogota (Cundinamarca) traditionally watered with the highly polluted waters of the Bogota River, were sampled to quantify Cd and As accumulated with irrigation. Soil of site six representatives of Rio Bogota series (fine clay, mixed, isothermic family of Fluventic tropaquepts) was selected for greenhouse experiments directed to show: a) Actual content of Cd and As in one of the most representative horticultural soil sites of the plain savanna. b) The accumulation level of Cd and As in the edible parts of three different vegetables (lettuce, cucumber and carrots) watered with polluted waters with know and variable Cd and As concentrations. c) The effects of Cd and As on vegetable's yields

Implementation of a WRF-CMAQ Air Quality Modeling System in Bogotá, Colombia

Science.gov (United States)

Nedbor-Gross, R.; Henderson, B. H.; Pachon, J. E.; Davis, J. R.; Baublitz, C. B.; Rincón, A.

2014-12-01

Due to a continuous economic growth Bogotá, Colombia has experienced air pollution issues in recent years. The local environmental authority has implemented several strategies to curb air pollution that have resulted in the decrease of PM10 concentrations since 2010. However, more activities are necessary in order to meet international air quality standards in the city. The University of Florida Air Quality and Climate group is collaborating with the Universidad de La Salle to prioritize regulatory strategies for Bogotá using air pollution simulations. To simulate pollution, we developed a modeling platform that combines the Weather Research and Forecasting Model (WRF), local emissions, and the Community Multi-scale Air Quality model (CMAQ). This platform is the first of its kind to be implemented in the megacity of Bogota, Colombia. The presentation will discuss development and evaluation of the air quality modeling system, highlight initial results characterizing photochemical conditions in Bogotá, and characterize air pollution under proposed regulatory strategies. The WRF model has been configured and applied to Bogotá, which resides in a tropical climate with complex mountainous topography. Developing the configuration included incorporation of local topography and land-use data, a physics sensitivity analysis, review, and systematic evaluation. The threshold, however, was set based on synthesis of model performance under less mountainous conditions. We will evaluate the impact that differences in autocorrelation contribute to the non-ideal performance. Air pollution predictions are currently under way. CMAQ has been configured with WRF meteorology, global boundary conditions from GEOS-Chem, and a locally produced emission inventory. Preliminary results from simulations show promising performance of CMAQ in Bogota. Anticipated results include a systematic performance evaluation of ozone and PM10, characterization of photochemical sensitivity, and air

78 FR 47489 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Foreign...

Science.gov (United States)

2013-08-05

...., Bogota, Colombia; c/o PARQUES TEMATICOS S.A., Medellin, Colombia; c/o PROMO RAIZ S.A., Medellin, Colombia....V.; Linked To: OPERADORA NUEVA GRANADA, S.A. DE C.V.; Linked To: PARQUES TEMATICOS S.A.S.; Linked To...

Colombia: crusading efforts bring signs of progress.

Science.gov (United States)

Kendall, S

1989-01-01

Colombia, like many developing countries, has not committed resources to fight the AIDS problem. They have used the media for condom promotion and other sexually transmitted diseases. There have been 151 deaths caused by AIDS by the end of 1988; 344 cases are known, and 130 additional have tested positive to the virus. Health officials were reluctant to recognize the problem, thinking it was outside their country and that they would not be affected by it. Since then, they have tried to target high risk groups and educate them and assist with testing and counseling. There is a move to make the new drug zidovudine available, but few could afford its high price. The authorities have put transvestite prostitutes in jail and kept them for AIDS testing, but few woman prostitutes have been tested. Up until 1986, only 30% of the Red Cross blood bank supplies were being tested; now 80% are, although it comprises only about 40% of the total supply. Drugs are used heavily, but mostly smoked, in Colombia, yet there is some concern about increased use of needles. The majority of cases in Columbia have been homosexual and bisexual men, but prostitution among men and women is prevalent in large cities such as Bogota. Health officials state that education is the best deterrent, but must be perpetuated so people will be constantly reminded.

The marshes in Bogota

International Nuclear Information System (INIS)

Garcia Romero, Juan F; Moreno Gutierrez, Vanesa; Villalba Malaver, Juan Carlos

1998-01-01

A description is made, a diagnosis and some exits, to their preservation for each one of the 10 marshes that they still exist in Bogota. The marshes defines them the convention of Ramsar: As extensions of swamps, swamps or peat-bogs covered with water, be these of natural or artificial, permanent or temporary, stagnated regime or currents, sweet, salubrious or salted, included those of extensions of marine water whose depth in tide lowers don't exceed six meters. The marshes occupy the space that there are between the humid means and the dry means, and that they possess characteristic of both, for what they cannot be classified categorically as aquatic neither terrestrial. The characteristic of a marsh is the presence of water during sufficiently lingering periods as to alter the soils, their microorganisms and the flora and fauna communities

76 FR 59483 - Additional Designations, Foreign Narcotics Kingpin Designation Act

Science.gov (United States)

2011-09-26

... AMAZONICOS S.A.S., Bogota, Colombia; c/o PARQUES TEMATICOS S.A.S., Medellin, Colombia; c/o PROMO RAIZ S.A.S..., Distrito Federal, Mexico; c/o PARQUES TEMATICOS S.A., Medellin, Colombia; c/o PROMO RAIZ S.A., Medellin... 16 Sur No. 46A-49 Piso 6, Medellin, Colombia; NIT 800220730-4 (Colombia) [SDNTK] 7. PARQUES TEMATICOS...

78 FR 21495 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant To Executive Order 12978

Science.gov (United States)

2013-04-10

..., Colombia; c/o ASESORIAS DE INGENIERIA EMPRESA UNIPERSONAL, Cali, Colombia; c/o BONOMERCAD S.A., Bogota... S.A; Linked To: ASESORIAS DE INGENIERIA EMPRESA UNIPERSONAL; Linked To: BONOMERCAD S.A.; Linked To...

REDESCUBRIMIENTO DE MYRRHINIUM ATROPURPUREUM VAR. OCTANDRUM (MYRTACEAE: MYRTINAE EN COLOMBIA

Directory of Open Access Journals (Sweden)

PARRA-O. CARLOS

2003-12-01

Full Text Available Se documenta el redescubrimiento de Myrrhinium atropurpureum var. octandrum(Myrteae DC., Myrtaceae, taxón prácticamente desconocido en Colombia. Se presentala descripción del taxón, así como notas sobre su distribución en Colombia, elhábitat en que se desarrolla y su posible estatus dentro de las categorías de la ListaRoja de la UICN.

75 FR 21153 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Science.gov (United States)

2010-04-22

... Order: 1. FAVARONY URREA, Pedro F., c/o COPSERVIR LTDA., Bogota, Colombia; Cedula No. 167136671...) (individual) [SDNT]. 10. GARCIA DUQUE, Gustavo, Carrera 4 No. 12-20 of. 206, Cartago, Valle, Colombia; c/o...

Strategies for the implementation of an environmental mining plan of the construction materials in Bogota. Phase 1 Diagnostic

International Nuclear Information System (INIS)

Gonzalez Oviedo, Leopoldo; Parrado L, Guillermo; Cardenas, John Fernan

1995-01-01

The study contains the geologic aspects, miners and environmental of 10 areas selected in Bogota where construction materials exist, like they are sands, clays, and gravels, in each area a definition is made, the productive units are described, reserves, mining production and environmental impacts are given generated by the material exploitation; a prioritizing of potential areas is included to implement a miner-environmental plan of this industry in Bogota

78 FR 28701 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Science.gov (United States)

2013-05-15

... property and interests in property were blocked pursuant to the Order: 1. ARBOLEDA ARROYAVE, Pedro Nicholas (a.k.a. ARBOLEDA ARROYAVE, Pedro Nicolas), c/o DEPOSITO POPULAR DE DROGAS S.A., Cali, Colombia; c/ o...., Bogota, Colombia; Cedula No. 11352426 (Colombia) (individual) [SDNT]. 4. DUQUE MARTINEZ, Diego Fernando...

75 FR 34216 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Science.gov (United States)

2010-06-16

...., Quito, Ecuador; c/o INTERNACIONAL DE PROYECTOS INMOBILIARIOS S.A., Quito, Ecuador; POB Colombia; Cedula... COMERCIALIZADORA MORDUR S.A., Quito, Ecuador; c/o INTERNACIONAL DE PROYECTOS INMOBILIARIOS S.A., Quito, Ecuador..., Colombia; c/o GERENCIA DE PROYECTOS Y SOLUCIONES LTDA., Bogota, Colombia; c/o HOTEL LA CASCADA S.A...

[Evaluation of the National Vaccination Day in Bogota, D.C., 2001].

Science.gov (United States)

Prieto Alvarado, Franklyn E; de la Hoz Restrepo, Fernando P

2003-01-01

A national immunization day-NID, aimed at improving vaccination coverage, was carried out in Colombia in November 2001. The main objective of the study was to measure the proportion of children under 2 years either completing their immunization schedule or advancing through it by receiving doses during the NID. Besides, we also evaluated the proportion of lost opportunities for vaccination during the NID and the impact of the media (TV, ratio, newspapers, etc.) in advertising the NID. In order to evaluate the impact of immunization a cross sectional survey was carried out in Bogotá in the waiting rows of the 30 randomly selected vaccination posts; 623 participants were systematically chosen. The outcomes were analyzed by age, socioeconomic level and type of health insurance-SSS. Only children holding a vaccination card were considered eligible for the study. Most people become aware about NID through TV, 81%, followed by radio advertisements, 22%. After attending NID the proportion of fully vaccinated children, according to PAHO scheme, raised from 46% to 66%, a 43% increase. This increase was even higher among children aged less than 6 months (140% increment). There were no differences in the increment by social stratum or affiliation to the SSS. Among the children studied we identified a 24% of loss opportunities for vaccination that did not differ by socioeconomic level or SSS groups. Our results suggest that, despite its high costs, NID might be useful to transiently overcome barriers for adequate access to health services.

Chemical composition and source apportionment of PM10 at an urban background site in a high-altitude Latin American megacity (Bogota, Colombia).

Science.gov (United States)

Ramírez, Omar; Sánchez de la Campa, A M; Amato, Fulvio; Catacolí, Ruth A; Rojas, Néstor Y; de la Rosa, Jesús

2018-02-01

Bogota registers frequent episodes of poor air quality from high PM 10 concentrations. It is one of the main Latin American megacities, located at 2600 m in the tropical Andes, but there is insufficient data on PM 10 source contribution. A characterization of the chemical composition and the source apportionment of PM 10 at an urban background site in Bogota was carried out in this study. Daily samples were collected from June 2015 to May 2016 (a total of 311 samples). Organic carbon (OC), elemental carbon (EC), water soluble compounds (SO 4 2- , Cl - , NO 3 - , NH 4 + ), major elements (Al, Fe, Mg, Ca, Na, K, P) and trace metals (V, Cd, Pb, Sr, Ba, among others) were analyzed. The results were interpreted in terms of their variability during the rainy season (RS) and the dry season (DS). The data obtained revealed that the carbonaceous fraction (∼51%) and mineral dust (23%) were the main PM 10 components, followed by others (15%), Secondary Inorganic Compounds (SIC) (11%) and sea salt (0.4%). The average concentrations of soil, SIC and OC were higher during RS than DS. However, peak values were observed during the DS due to photochemical activity and forest fires. Although trace metals represented <1% of PM 10 , high concentrations of toxic elements such as Pb and Sb on RS, and Cu on DS, were obtained. By using a PMF model, six factors were identified (∼96% PM 10 ) including fugitive dust, road dust, metal processing, secondary PM, vehicles exhaust and industrial emissions. Traffic (exhaust emissions + road dust) was the major PM 10 source, accounting for ∼50% of the PM 10 . The results provided novel data about PM 10 chemical composition, its sources and its seasonal variability during the year, which can help the local government to define control strategies for the main emission sources during the most critical periods. Copyright © 2017 Elsevier Ltd. All rights reserved.

75 FR 79440 - Additional Designations, Foreign Narcotics Kingpin Designation Act

Science.gov (United States)

2010-12-20

..., Colombia; c/o FERTILIZANTES LIQUIDOS DE LA SABANA LTDA., Bogota, Colombia; Calle 109 No. 21-41 Apto. 403...) [SDNTK] 13. FERTILIZANTES LIQUIDOS DE LA SABANA LTDA. (a.k.a. FERTILISA LTDA.), Calle 98 Bis No. 57-66...

Towards a radiation safety culture at Universidad Nacional de Colombia

International Nuclear Information System (INIS)

Poveda, Jairo F.; Munera, Hector A.

2008-01-01

Full text: During the 20th century, nuclear and radiation techniques for research, teaching, and medical and engineering practice slowly appeared at the National University of Colombia, mainly at the Bogota, Medellin and Manizales branches. Each individual laboratory or researcher obtained the license for the use of the radioactive source, or radiation emitting apparatus. However, the University as a whole does not have as yet a Radiation Safety Manual, nor an inventory of laboratories using radiation. From the viewpoint of radiation safety and culture, this situation is undesirable, and may easily lead to inappropriate waste management practices, including the possibility of orphan sources (one such source has been already found). As part of the program of environmental management of dangerous wastes promoted by the National Division of Laboratories of our University, an office of radiation safety was created in the year 2006. This paper describes the situation that was found, the activities that have been carried out, some of the difficulties that we have met, and the plans that we have to help shape a safety culture at our institution. Currently we are pursuing an inventory of laboratories using radioactive sources and radiation emitting apparatuses, starting with the branches in Bogota and Manizales which are perceived as the most urgent to deal with. Fortunately, the branch in Medellin has been for about a decade under the care of a former radiation safety officer of our national Institute of Nuclear Affairs, who presently teaches there. During 2006 and 2007, 13 laboratories using radioactive sources were visited in the Bogota branch. Safety procedures and waste handling protocols were checked, safety manuals prepared and/or revised, and recommendations for safety culture provided. During 2008 we will visit Manizales, and will continue visiting a number of X-ray machines used in the Bogota branch for engineering, veterinary, and diagnostic, and surgery medical

A methodology of design for a one-variable neural network model to forecast the minimum temperature on the Mosquera zone, Cundimarca, Colombia

International Nuclear Information System (INIS)

Bonilla, Jose Ebert; Ramirez, Jairo; Ramirez, Oscar; Leon, Gloria and others

2006-01-01

The meteorological phenomena are factors that affect the economy, especially on a country like Colombia, which sustainability is based highly on agricultural products like corns, potato and flowers, plants of a paramour landscape like Bogota savannah. Among this phenomenon is the extreme minimum temperature (frost damage) it is a result of the non-lineal interactions of many atmospheric phenomena, for all that, frost damage forecast is very hard to accomplish with traditional methods. The approach of the project is to process this time series with an artificial neural network; it generals a now casting forecast on the zone of Mosquera

SOUTH AMERICA: Looking for partners

International Nuclear Information System (INIS)

Anon.

1991-01-01

A Regional Meeting on Fundamental Physics organized at the CIF International Physics Centre in Bogota, Colombia, in April, looked at future international collaboration possibilities for physicists from the South American Andean region in general, and from Colombia in particular

Hydrological balance of Chicu River basin, using nuclear techniques

International Nuclear Information System (INIS)

Ramos P, R.T.; Valderrama B, J.O.

1992-01-01

This thesis made part of the ARCAL X III Project, referring to the groundwater study en the Bogota Plain (Sabana de Bogota, Colombia). In the Bogota plain, is found located the Chicu River basin, in such basin are located two towns Tabio and Tenjo, in this zone have been taken advantage the groundwater in the last years. The objective of this work was determined by means of isotopic techniques, the determination of the groundwater origin and its quality using physical and chemical parameters

Actions for the environmental adequateness and emissions control at the Martin del Corral power plant-Termozipa; Obras de adecuacion ambiental y control de emisiones para la central termoelectrica Martin del Corral - Termozipa

Energy Technology Data Exchange (ETDEWEB)

Arevalo Osorio, Luis [Empresa de Energia de Bogota, Bogota (Colombia)

1997-12-31

In this paper the general data on the Martin del Corral-Termozipa, of Colombia, fossil fueled power plant are exposed. The results of a study to determine the environmental impact originated in the influence zone of this Power Plant are presented, particularly on the Bogota River. The study was framed into the environmental policy driven by the Colombian sector. Different solutions addressed to the optimization of the handling, capacity and control of the emissions and counteract the pollution possibilities of the Bogota River are described [Espanol] En esta ponencia se exponen datos generales de la central termoelectrica Martin del Corral - Termozipa-, de Colombia. Se presentan los resultados de un estudio para determinar el impacto ambiental ocasionado en la zona de influencia de esta central, y en particular sobre el rio Bogota. El estudio se enmarco dentro de la politica ambiental impulsada por el sector colombiano. Se describen diversas soluciones encaminadas a optimizar el manejo, capacidad y control de las emisiones y contrarrestar las posibilidades de contaminacion del rio Bogota

Actions for the environmental adequateness and emissions control at the Martin del Corral power plant-Termozipa; Obras de adecuacion ambiental y control de emisiones para la central termoelectrica Martin del Corral - Termozipa

Energy Technology Data Exchange (ETDEWEB)

Arevalo Osorio, Luis [Empresa de Energia de Bogota, Bogota (Colombia)

1996-12-31

In this paper the general data on the Martin del Corral-Termozipa, of Colombia, fossil fueled power plant are exposed. The results of a study to determine the environmental impact originated in the influence zone of this Power Plant are presented, particularly on the Bogota River. The study was framed into the environmental policy driven by the Colombian sector. Different solutions addressed to the optimization of the handling, capacity and control of the emissions and counteract the pollution possibilities of the Bogota River are described [Espanol] En esta ponencia se exponen datos generales de la central termoelectrica Martin del Corral - Termozipa-, de Colombia. Se presentan los resultados de un estudio para determinar el impacto ambiental ocasionado en la zona de influencia de esta central, y en particular sobre el rio Bogota. El estudio se enmarco dentro de la politica ambiental impulsada por el sector colombiano. Se describen diversas soluciones encaminadas a optimizar el manejo, capacidad y control de las emisiones y contrarrestar las posibilidades de contaminacion del rio Bogota

Strategies for the implementation of an environmental mining plan of the construction materials in Bogota. Phase 1 Diagnostic; Estrategias para la implementacion de un plan integral de gestion minero-ambiental de la industria extractiva de materiales de la construccion en la Sabana de Bogota. Fase I Diagnostico

Energy Technology Data Exchange (ETDEWEB)

Gonzalez Oviedo, Leopoldo; Parrado L, Guillermo; Cardenas, John Fernan

1995-07-01

The study contains the geologic aspects, miners and environmental of 10 areas selected in Bogota where construction materials exist, like they are sands, clays, and gravels, in each area a definition is made, the productive units are described, reserves, mining production and environmental impacts are given generated by the material exploitation; a prioritizing of potential areas is included to implement a miner-environmental plan of this industry in Bogota.

The boundaries of poverty in Bogota

Directory of Open Access Journals (Sweden)

Consuelo Uribe Mallarino

2016-07-01

Full Text Available The article proposes an analytical perspective on poverty with a multidimensional approach, not only as an aggregate of variables and indicators, but also using a probing strategy that considers the way in which it is perceived between the groups receiving programs to alleviate poverty or use subsidized public services, and those without. Based on tools for quantitative and qualitative analysis applied to data collected on a sample of residents of Bogota, the authors analyze how the boundaries of sense on poverty are related to both objective and subjective factors related to being or not users of these programs, socioeconomic and educational conditions, as well as political participation, degree of association and use of mechanisms to enforce civil rights.

75 FR 27118 - Additional Designations, Foreign Narcotics Kingpin Designation Act

Science.gov (United States)

2010-05-13

... of State, and the Secretary of Homeland Security when designating and blocking the property and... assisting in, or providing financial or technological support for or to, or providing goods or services in.../o NEGOCIAMOS MCM LTDA, Bogota, Colombia; DOB 16 Jul 1968; Citizen Colombia; Cedula No. 51921171...

Evaluation of the ''Sabana de Bogota'' aquifer using isotopes techniques

International Nuclear Information System (INIS)

Torres, E.; Jimenez, G.; Obando, E.; Sanchez, L.; Alayon, E.

1987-01-01

Groundwater from the Sabana de Bogota area was studied by means of isotopic techniques such as isotope analysis, injection of tracers for determination of hydrogeological parameters, velocity measurements using tracers. These results combined with the ones obtained by conventional techniques were used to determine recharge area, origin, equipotencial lines and direction of groundwater. The results show that a combined application of classical and nuclear methods may establish rather reasonable hydrogeological concepts without investing much time and money

Genetic architecture of male sterility and segregation distortion in Drosophila pseudoobscura Bogota-USA hybrids.

Science.gov (United States)

Phadnis, Nitin

2011-11-01

Understanding the genetic basis of reproductive isolation between recently diverged species is a central problem in evolutionary genetics. Here, I present analyses of the genetic architecture underlying hybrid male sterility and segregation distortion between the Bogota and USA subspecies of Drosophila pseudoobscura. Previously, a single gene, Overdrive (Ovd), was shown to be necessary but not sufficient for both male sterility and segregation distortion in F(1) hybrids between these subspecies, requiring several interacting partner loci for full manifestation of hybrid phenomena. I map these partner loci separately on the Bogota X chromosome and USA autosomes using a combination of different mapping strategies. I find that hybrid sterility involves a single hybrid incompatibility of at least seven interacting partner genes that includes three large-effect loci. Segregation distortion involves three loci on the Bogota X chromosome and one locus on the autosomes. The genetic bases of hybrid sterility and segregation distortion are at least partially--but not completely--overlapping. My results lay the foundation for fine-mapping experiments to identify the complete set of genes that interact with Overdrive. While individual genes that cause hybrid sterility or inviability have been identified in a few cases, my analysis provides a comprehensive look at the genetic architecture of all components of a hybrid incompatibility underlying F(1) hybrid sterility. Such an analysis would likely be unfeasible for most species pairs due to their divergence time and emphasizes the importance of young species pairs such as the D. pseudoobscura subspecies studied here.

Incidence of public expenditure on the human development index in Bogota, 1995-2010

Directory of Open Access Journals (Sweden)

Mónica Consuelo Rodríguez Torres

2012-01-01

Full Text Available This paper seeks to test the hypothesis that social public expenditure per capita invested in Bogota has had a significant influence on the improvement of the city’s human development. For this purpose, the Human Development Index (HDI for the capital between 1995-2010 is estimated, using the new methodology proposed by the UNDP in 2010. Thus, a retrospective estimation of the life expectancy, salaries, and educational achievement rates is carried out, the last as a combination between the average years of education and expected years of instruction. A qualitative analysis is then presented, between the HDI components and the social public expenditure invested through politics, programs, projects carried out in the city, according to the District Development Plan “Bogotá positiva, para vivir mejor (Positive Bogota, to Live Better”. Finally, a quantitative analysis of this relation is made and it is concluded that social public spending per capita is significant to explain the HDI, since there is a long-term and stable relation between the two variables.

2015-2016 Travel and Hospitality Expense Reports for Stephen ...

International Development Research Centre (IDRC) Digital Library (Canada)

Ruxandra Staicu

Attend meeting in Colombia on IDRC's engagement in Canada's peace process cooperation. Date(s):. 2016-03-13 to 2016-03-19. Destination(s):. Bogota, Colombia. Air fare: $2,187.40. Other. Transportation: $206.60. Accommodation: $670.32. Meals and. Incidentals: $422.96. Other: $73.74. Total: $3,561.02. Comments:.

76 FR 48946 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Science.gov (United States)

2011-08-09

... alia, of the International Emergency Economic Powers Act (50 U.S.C. 1701-1706) (``IEEPA''), issued... Secretary of State: (a) to play a significant role in international narcotics trafficking centered in..., Colombia; c/o Inversiones Sardi Alzate S.C.S., Cali, Colombia; c/o Outsourcing De Operaciones S.A., Bogota...

The decision of the International Court of Justice related to preliminary exceptions in the Nicaragua v. Colombia case

Directory of Open Access Journals (Sweden)

Rafael Nieto Navia

2010-05-01

Full Text Available This article is divided into three main parts. The fi rst part presents the precedents in the case relating to delimiting the Caribbean Sea boundary between Nicaragua and Colombia. It analyzes the competence of the International Court of Justice – ICJ (the Court in accordance with Article 36 of the Statute of the Court; consequently, it studies the Declaration of the acceptance of the Competence of the Court presented by Colombia to the Permanent Court of International Justice in 1937 as well as the Bogota Pact of 1948 as to its applicability and breadth as regards the 1928 EsguerraBárcenas Treaty. The second part presents a detailed analysis of the decision of the Court on the preliminary exceptions in which it was determined that the sovereignty of the islands of San Andres, Providencia, and Santa Catalina was Colombian, that the Esguerra-Bárcenas Treaty was not treaty delimiting maritime boundaries and that it (the Court was competent to get to the foundation of the matter. The third part sets out the actions which still must be completed relative to the foundation of the case.

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (South Florida): Black, Red and Nassau Groupers

Science.gov (United States)

1989-08-01

Baltimore, Md. 05 pp. Colombia. Instituto de Desarrollo de los Recursos Naturales , Bogota, Colombia. 391 pp. Goodyear, C.P. 1988. The Gulf of Mexico fishery...Venezuela. Fundacion La Salle de 6200. 54 pp. Ciencias Naturales . Caracas, Venezuela. 951 pp. Deue], D.G., and j.R. Clark. 1968. The Coln, P.L. 1982

77 FR 41479 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Foreign...

Science.gov (United States)

2012-07-13

..., 1999, the Kingpin Act was signed into law by the President of the United States. The Kingpin Act... traffickers and their organizations on a worldwide basis, with the objective of denying their businesses and.../o HOTELES Y BIENES S.A., Bogota, Colombia; Calle 5A No. 43A-73, Medellin, Colombia; DOB 5 Dec 1969...

PARAMETERS, U.S. Army War College Quarterly. Volume 24, Number 3, Autumn 1994

Science.gov (United States)

1994-01-01

Estructuras politicas de Colombia, Coleccion "Monografias y Docu- mentos," #3 (Bogota: CIAS, 1969), p. 5; and "Encuesta Nacional," Semana (Bogota), I I...procedural insights into a world in which instant communications fr.m the opponent’s capital not only bypass policymaking bureaucracies, but can allow...other. We cannot consume our equipment or human capital in operations today and ignore investments that prepare us for future contingencies. We cannot

Quaternion analysis of generalized electromagnetic fields in chiral media

International Nuclear Information System (INIS)

Bisht, P. S. . Email. ps_bisht123@rediffmail.com

2007-01-01

The time dependent Maxwell's equations in presence of electric and magnetic charges has been developed in chiral media and the solutions for the classical problem are obtained in unique, simple and consistent manner. The quaternionic reformulation of generalized electromagnetic fields in chiral media has also been developed in compact and consistent way. Simulation of neutron backscattering process applied to organic material detection. Forero Martinez, Nancy Carolina; Cristancho, Fernando (Nuclear Physics Group, Universidad Nacional de Colombia, Bogota D.C. (Colombia)) Abstract Atomic and nuclear physics based sensors might offer new possibilities in de-mining. There is a particular interest in the possibility of using neutrons for the non-intrusive detection of hidden contraband, explosives or illicit drugs. The Neutron Backscattering Technique, based on the detection of the produced thermal neutrons, is known to be a useful tool to detect hidden explosives which present an elevated concentration of light elements (H, C, N, O). In this way we present the simulated results using the program package Geant4. Different variables were modified including the soil composition and the studied materials. (Author)

Violence in three Latin American cities: A comparative study ...

International Development Research Centre (IDRC) Digital Library (Canada)

The cities, Bogota (Colombia), Lima (Peru), and Santiago (Chile), have all experienced ... Researchers will document government programs and assess the daily ... International Water Resources Association, in close collaboration with IDRC, ...

Spatiotemporal variability and meteorological control of particulate matter pollution in a large open-pit coal mining region in Colombia

Science.gov (United States)

Morales Rincon, L. A.; Jimenez-Pizarro, R.; Porras-Diaz, H.

2012-12-01

Luis Morales-Rincon (1), Hernan Porras-Diaz (1), Rodrigo Jiménez (2,*) (1) Geomatic Research Group, Department of Civil Engineering, Universidad Industrial de Santander, Bucaramanga, Santander 680002, Colombia; (2) Air Quality Research Group, Department of Chemical and Environmental Engineering, Universidad Nacional de Colombia, Bogota, DC 111321, Colombia *Corresponding author: phone +57-1-316-5000 ext. 14099, fax +57-1-316-5334, e-mail rjimenezp@unal.edu.co The semi-desertic area of Central Cesar, Colombia, produced approximately 44 million tons of coal in 2011. This mining activity has been intensively developed since 2005. There are currently 7 large-scale mining projects in that area. The coal industry has strongly impacted not only the ecosystems, but also the neighboring communities around the coal mines. The main goal of the research work was to characterize spatial and temporal variations of particulate matter (total suspended particulates - TSP - and particulate matter below 10 μm - PM10) as measured at various air quality monitoring stations in Cesar's coal industry region as well as to study the relationship between these variability and meteorological factors. The analysis of the meteorological time series of revealed a complex atmospheric circulation in the region. No clear repetitive diurnal circulation patterns were observed, i.e. statistical mean patterns do not physically represent the actual atmospheric circulation. We attribute this complexity to the interdependence between local and synoptic phenomena over a low altitude, relatively flat area. On the other hand, a comparison of air quality in the mining area with a perimeter station indicates that coal industry in central Cesar has a mayor effect on the levels of particulate matter in the region. Particulate matter concentration is highly variable throughout the year. The strong correlation between TSP and PM10 indicates that secondary aerosols are of minor importance. Furthermore, particle

Conventional radiology in the bony compromise of Langerhans cells Histiocytosis

International Nuclear Information System (INIS)

Morales, Nilson; Gonzalez, Claudia Patricia; Melendez, Patricia; Terselich, Gretty

1999-01-01

We present a descriptive study of 47 patients who attended the National Cancer Institute in Bogota, Colombia with pathological diagnosis of Langerhans cell histiocytosis. We reviewed the most frequent conventional x-ray findings

The man that saw grow the plants

International Nuclear Information System (INIS)

Cardona Vallejo, Mateo

2002-01-01

The author makes a reminder of the founder of the Botanical Garden in Bogota (Colombia) Enrique Perez Arbelaez, speaks of his life, studies, publications and contributions to the knowledge of the Colombian flora

Pesticide Flow Analysis to Assess Human Exposure in Greenhouse Flower Production in Colombia

Directory of Open Access Journals (Sweden)

Claudia R. Binder

2013-03-01

Full Text Available Human exposure assessment tools represent a means for understanding human exposure to pesticides in agricultural activities and managing possible health risks. This paper presents a pesticide flow analysis modeling approach developed to assess human exposure to pesticide use in greenhouse flower crops in Colombia, focusing on dermal and inhalation exposure. This approach is based on the material flow analysis methodology. The transfer coefficients were obtained using the whole body dosimetry method for dermal exposure and the button personal inhalable aerosol sampler for inhalation exposure, using the tracer uranine as a pesticide surrogate. The case study was a greenhouse rose farm in the Bogota Plateau in Colombia. The approach was applied to estimate the exposure to pesticides such as mancozeb, carbendazim, propamocarb hydrochloride, fosetyl, carboxin, thiram, dimethomorph and mandipropamide. We found dermal absorption estimations close to the AOEL reference values for the pesticides carbendazim, mancozeb, thiram and mandipropamide during the study period. In addition, high values of dermal exposure were found on the forearms, hands, chest and legs of study participants, indicating weaknesses in the overlapping areas of the personal protective equipment parts. These results show how the material flow analysis methodology can be applied in the field of human exposure for early recognition of the dispersion of pesticides and support the development of measures to improve operational safety during pesticide management. Furthermore, the model makes it possible to identify the status quo of the health risk faced by workers in the study area.

Notas sobre la Flora de Colombia y países vecinos, III

Directory of Open Access Journals (Sweden)

Dugand Armando

1969-06-01

Full Text Available Continuación (parte III de la nueva serie de notas botánicas iniciada hace tres años en Phytologia (vol. 13, no. 6: 379-400. 1966, y cuya segunda parte se publicó recientemente en Caldasia (vol, 10, no. 47: 173-213. 1968, relativas en su mayor parte a la flora xerófila y subxerófila de la región costera del Caribe en Colombia y países vecinos, particularmente Venezuela.  En ellas se hacen observaciones sobre la taxonomía, nomenclatura, morfología, distribución geográfica, hábitat, y otras varias, de las siguientes plantas: ASCLEPIADACEAE Matelea albiflra (Karst. Dugand. BIGNONIACEAE Anemopaegma chrysoleucum. (Kth. in H. & B. Sandw. # Arrabidaea candicans (L. C. Rich. DC. Arrabidaea conjugata (VeIl. Mart. ex DC. Arrabidaea florida DC. # Arrabidaea pleei DC. Clytostoma cuneatum Dugand. Clytostoma pterocalyx Spr. ex Urb. # Onohualcoa helicocalyx (O. Kze. Sandw. Phryganocydia uliginosa Dugand. Romeroa verticillata Dugand. # Roseodendron chryseum. (Blake Miranda. Tabebuia dugandii StandI. BOMBACACEAE Pseudobombax maximum A. Robyns. LEGUMINOSAE·FABOIDEAE Uribea tamarindoides Dugand & Romero. RUBIACEAE Guettarda eliadis StandI. Sickingia klugei StandI. Tal vez con la sola excepción de Arrabidaea florida DC., de cuya existencia en Colombia no hay -que yo sepa- ninguna información anterior (a menos que la colección original sea realmente del Caquetá colombiano como bien pudiera serlo, véase nota al pie de la página respectiva en este trabajo , todas las especies enumeradas arriba ya han sido catalogadas antes en la flora de este pais, ora con el mismo nombre con que figuran en la Iista, ora con otro que ha caido en desuso necesario o se considera sinonimo del que se da aqui. Las de este ultimo grupo se seiialan con el signo #.

Environmental quality evaluation for towns in Bogota; An approach to the construction of indexes of environmental quality

International Nuclear Information System (INIS)

Escobar, Luis; Bermudez, Tatiana

2004-01-01

This paper is a conceptual and methodological estimate for the construction of a synthetic indicator that allows one to come a step closer to the diagnosis of the environmental conditions of the nineteen administrative units of Bogota known as localidades. Here the contained information is synthesized in eight simple selected indicators, the index is constructed by applying analysis of principal components, of which the alignment of the localidades is derived in accordance with the value that it takes in the environmental quality index. Once the method of calculation is applied, the results indicate that the conditions of environmental quality if Bogota are not homogeneous, clearly existing environmental differences between localidades in the north and south. Also prioritization and analysis index of environmental qualities per localidades introduced, of which the principal determinants of the index of each localidad are introduced, thus providing the decision makers with important input, in order to define the base line as a stating point of the urban environmental management

Analysis of the existing correlations of effective friction angle for eastern piedmont soils of Bogota from in situ tests

Directory of Open Access Journals (Sweden)

July E. Carmona-Álvarez

2015-07-01

Full Text Available To estimate the effective friction angle of soil from in situ test is a complicated job, due to high rates of strain existing in this kind of tests, which tend to be too invasive and disturb the vicinities of test depth, even the sample that eventually is taken at the site. Likewise, the most of the correlations found in the current bibliography to obtain the effective friction angle using field tests, have been developed for soils from different regions. For that reason when are implemented on tropical soils present high scatter, to compare the field parameter values with real results obtained at the lab. This research aims to use in situ tests define through of analysis of different correlations, which fits adequately to the specific conditions of the piedmont soils of Bogota. For the present study will be utilized data from SPT (widely used in Colombia and SPT-T (never before conducted in the country, carried out considering the appropriated norms to each test, taking in account to SPT-T, doesn’t exist local standard governing such tests. The correlations for field procedures of the tests implemented were for effective confining and energy transference of the SPT hammer, since the state-of-the-art mentions it as the most affect the reliability of the final results. The final results show the tendency of the methodologies used to obtain the correlation, in relation with the real value of effective friction angle from of lab tests.

Breast Cancer Screening Coverage with clinical examination and Mammography Among insured women in Bogota

International Nuclear Information System (INIS)

Arboleda, Walter; Murillo Raul; Pinero, Marion

2009-01-01

The objective is to determine the coverage of clinical breast examination (CBE) and mammography for screening of breast cancer among a group of insured women in Bogota. Methods: A telephone survey was carried out with 4,526 women between the ages of 50 and 69, residing in Bogota or its suburbs, who were insured by one of three commercial health plans. Women with a history of breast cancer were excluded. Screening coverage was estimated as the proportion of women who had had a mammography or CBE. Estimates were established for lifetime frequency, two years prior the survey, and one year prior the survey. Factors associated with screening procedures were analyzed with calculations based on adjusted OR. Results: Lifetime frequency of CBE was 59.3% and 79.8% for mammography; and 49.7% and 65.6% of women respectively underwent the tests for screening purposes; the remainder, for diagnostic purposes (breast symptoms). CBE reported a 34.2% one year coverage and mammography reported a 54% two years coverage. Screening was associated to cancer education and family history of breast cancer. Conclusion: Coverage of CBE for screening purposes is low. Mammography coverage is above that required by the Colombian Health Ministry, but below that reported by developed countries.

[PHYSICAL ACTIVITY LEVELS, PHYSICAL FITNESS AND SCREE TIME AMONG CHILDREN AND ADOLESCENTS FROM BOGOTÁ, COLOMBIA].

Science.gov (United States)

Prieto-Benavides, Daniel Humberto; Correa-Bautista, Jorge Enrique; Ramírez-Vélez, Robinson

2015-11-01

to investigate the association between objective measures of physical activity levels, physical fitness and screen time in Colombia children and adolescents from Bogota, Colombia. a sample of 149 healthy Colombian youth, children and adolescents (9-17.9 years old) participated in the study. Physical activity level was assessed over 7 days using an accelerometer. Weight, height, waist circumference, hip waist, subscapular/ triceps skinfold thicknesses and self-reported screen time (television/internet and videogame-viewing time) were measured. Aerobic capacity, handgrip strength, standing broad jump, vertical jump, speed/agility and flexibility were used as indicators of physical fitness. in girls with a high level of physical activity had favorable aerobic capacity (r = 0.366) and inverse relationship with subscapular/triceps skinfold thicknesses (r = -0.257) and (r = -0,237) p < 0.05, respectively. In boys, vigorous physical activity were associated with higher values of flexibility (r = 0.277) and aerobic capacity (r = 0.347), p < 0.05. Finally, the participants who watched 2 h or less of television per day showed 1.81 times (95%CI 1.401 to 2.672) that met physical activity guidelines. the healthy Colombian youth who reported moderate to vigorous objective measures of physical activity levels, presented higher levels in physical fitness especially in aerobic capacity and flexibility and lower values in subscapular/triceps skinfold thicknesses. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

A propósito de la introducción de aislamientos de Phytophthora infestans para investigación en Colombia Sorne thoughts concerning the import of the mating type A2 of Phytophthora infestans into Colombia

Directory of Open Access Journals (Sweden)

García Dominguez Celsa

1997-12-01

Full Text Available Phitophthora infestans es un patógeno heterotálico que requiere dos tipos de apareamiento, A 1 y A2, para que haya reproducción sexual. El tipo A 1 se encontraba distribuido en todas las zonas productoras de papa del mundo; pero, al final de los años 1970s el tipo A2 salió de México (su centro de origen, hacia Europa y al resto del mundo. Como en Colombia no se conocía la composición de las poblaciones de este patógeno, dos grupos de investigación de la Universidad Nacional iniciaron su estudio. El grupo de la Sede Bogotá optó por la importación del tipo A2 para realizar los trabajos de investigación. El presente comunicado es una reflexión sobre los riesgos y los cuidados que se deben tener al importar un patógeno que no está
presente en el país.Phytophthora infestans is an heterothallic pathogen that requires the presence oftwo mating types, A1 and A2, for sexual reproduction. The A1 type had a worldwide distribution, but at the end of the 70s the A2 migrated from Mexico (the center of origin to Europe and from there to the rest of the world. Since in Colombia there was no information conceming the composition of the population of this pathogen, two research groups from the Universidad Nacional de Colombia initiated studies to determine the composition of the population of this pathogen. The group from Bogota imported the A2 type. The present work contains some thoughts on the risk involved when importing alien and exotic pathogens.

The FARC and Hugo Chavez: Is Contemporary Venezuela a Threat to Colombia?

Science.gov (United States)

2010-12-01

Smith, The Emergence of Liberation Theology: Radical Religion and the Social Movement Theory (Chicago: Chicago University Press, 1991), 59. 16...Socialismo del Siglo XXI (Bogota: Fundacion para la Investigacion y la Cultura, 2007), 50. 146 Cristóbal Valencia Ramírez, “Venezuela’s Bolivarian... Siglo XXI. Bogota: Fundacion para la Investigacion y la Cultura, 2007. Discovery en Español. “Fuga de las FARC.” http://www.tudiscovery.com/web

Non - Vegetated Standard Bioretention Structure Hydrodynamic Soil Characterization For Ponding - Layer Optimum Thickness Determination With A Distinctive Urban - Region Rainfall Event In Bogota

Science.gov (United States)

Velasco Ávila, Frank; Acero Rivero, Germán Eduardo; Angulo Jaramillo, Rafael

2017-04-01

Aiming to propose a system, in accordance with Best Management Practices (BMP) kind of structures, specifically a standard bioretention system in Bogota city, and in order to apply the inverse solution methodology on Hydrus - 1D, it is mandatory to determine each θ_s; θ_r; α;n and ks parameters in van Genuchten - Mualem function, without considering the hysteresis phenomenon, for a standard bioretention system composing soils, as well as required components and dimensions to implement the bioretention structure in Bogota. First, a bioretention structure general dimensioning was carried out based on current urban landscaping regulations and recommendations given by the sewage - system service provider in Bogota city. Soil composing and design were performed after information gathering and previous investigation on bioretention systems dimensioning from different sources such as manuals. To give an adequate interpretation of the vadose zone, a soil column experimental prototype was built to be able to control and measure the intervening parameters in the subsoil unidimensional flow description, such as capillary pressure, soil water saturation, inflow and outflow. Thirteen sensor - based devices were built to measure the inverse model required parameters. It is important to underline that all the designed instrumentation was based on low cost electronic development. In addition, the whole instrumentation system is controlled by an Arduino Mega PLC and was designed and built as a personal initiative by the author of this work. For signal processing and data capturing, a commercial Lab View version intuitive program was designed, to be able to create a user-friendly interface to make real-time sensor visualisation and control. Finally, all the hydrodynamic characterisation for the studied soils was made through a Hydrus-1D inverse model and laboratory experimenting and obtained results. In addition, several direct models were run in order to determinate both

Norma categorial para el español de Bogotá, Colombia Category norm for the Spanish spoken in Bogota, Colombia

Directory of Open Access Journals (Sweden)

Albeiro Migue Ángel Ramírez Sarmiento

2010-07-01

Full Text Available En este trabajo presentamos los resultados de un estudio elaborado en Bogotá con 210 estudiantes universitarios de 5 instituciones con diferentes características sociodemográficas, con el fin de establecer las normas categoriales léxicas. Se utilizaron las 56 categorías léxico-semánticas usadas en el clásico estudio de Battig y Motague (1969 y se recogieron más de 7800 palabras que fueron organizadas por rango y moda. En la revisión bibliográfica realizada no se encontraron trabajos de esta naturaleza para el español colombiano (o latinoamericano, y se espera que sus resultados sean usados en protocolos para el campo de la terapia del lenguaje y los estudios psicolingüísticos. Los datos recogidos fueron comparados con uno de los estudios de norma categorial realizados para el español ibérico.In this article, we present the results of a study carried out in Bogotá, Colombia with 210 university students from five different universities pertaining to diverse socio-demographic groups. The objective of the study was to establish the lexical category norms. 56 lexical-semantic categories used by Battig and Montague (1969 in their classic study were employed. More than 7800 words were collected and organized by range and mode. There are no other studies on this subject for Colombian or Latin American Spanish. We hope that the results presented here will be used both in psycholinguistic and language therapy studies. The collected data were compared to one of the category norm studies made for European Spanish.

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...

Advanced DC/DC converters

CERN Document Server

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.

Mediating Pathways in the Socio-Economic Gradient of Child Development: Evidence from Children 6-42 Months in Bogota

Science.gov (United States)

Rubio-Codina, Marta; Attanasio, Orazio; Grantham-McGregor, Sally

2016-01-01

Research has previously shown a gap of near 0.5 of a standard deviation (SD) in cognition and language development between the top and bottom household wealth quartile in children aged 6-42 months in a large representative sample of low- and middle-income families in Bogota, using the Bayley Scales of Infant and Toddler Development. The gaps in…

Neuroimage of the toxoplasmosis in the patient with AIDS

International Nuclear Information System (INIS)

Paez, Luis Alfredo; Araque, Julio Mario; Lozano, Alfonso Javier

2001-01-01

We performed a review of literature on CNS involvement in AIDS patients. Besides several cases seen in the San Juan de Dios Hospital in Bogota, Colombia, are illustrated with tomographic images. We propose an algorithmic decision tree in the patient with AIDS and neurological symptoms

Biological control of Trialeurodes vaporariorum by Encarsia formosa on tomato in unheated greenhouses in the high altitude tropics

NARCIS (Netherlands)

Vis, de R.M.J.; Lenteren, van J.C.

2008-01-01

Biological control of Trialeurodes vaporariorum (Westwood) by Encarsia formosa Gahan was tested during three consecutive production cycles (16-28 weeks) on a beef tomato (Solanum lycopersicum L.) crop in a glasshouse and a plastic greenhouse on the Bogota Plateau in Colombia. During the course of

The management of water providing strategic ecosystems. The case of the basins that supply Medellin and Bogota in Colombia

International Nuclear Information System (INIS)

Cardenas Agudelo, Maria Fernanda

2013-01-01

The population growth and the urban concentration involve a sustained increment in water demand, which requires an adequate effort and management of the ecosystems that provide the liquid to guarantee a plenty future offer. The performance of the entities in charge of the management of such ecosystems and the results obtained in the basins that supply drinkable water to two cities in Colombia are analyzed; financial topics and their relation with the local community are considered. Management is delegated to governmental entities, whose work is insufficient and unsatisfactory. Thus, application of economical, legal and social tools is proposed in order to improve ecosystem's conservation and life quality of farmers that inhabit in their influence areas, partially transferring management to the local community's orbit.

Preliminary methodological proposal for estimating environmental flows in projects approved by the ministry of environment and sustainable development (MADS), Colombia

International Nuclear Information System (INIS)

Pinilla Agudelo, Gabriel A; Rodriguez Sandoval, Erasmo A; Camacho Botero, Luis A

2014-01-01

A methodological proposal for estimating environmental flows in large projects approved by Agencia Nacional de Licencias Ambientales (ANLA) in Colombian rivers was developed. The project is the result of an agreement between the MADS and the Universidad Nacional de Colombia, Bogota (UNC). The proposed method begins with an evaluation of hydrological criteria, continues with a hydraulic and water quality validation, and follows with the determination of habitat integrity. This is an iterative process that compares conditions before and after the project construction and allows to obtain the magnitude of a monthly flow that, besides preserving the ecological functions of the river, guarantees the water uses downstream. Regarding to the biotic component, the proposal includes the establishment and monitoring of biotic integrity indices for four aquatic communities (periphyton, macro invertebrates, riparian vegetation, and fish). The effects that flow reduction may produce in the medium and long term can be assessed by these indices. We present the results of applying the methodology to several projects licensed by the MADS.

Seismological observations at the Northern Andean region of Colombia: Evidence for a shallowly subducting Caribbean Slab and an extensional regime in the upper plate

Science.gov (United States)

Monsalve, G.; Cardona, A.; Yarce, J.; Alvira, D.; Poveda, E.

2013-05-01

A number of seismological observations, among which we can mention teleseismic travel time residuals, P to S receiver functions and Pn velocity quantification, suggest a clear distinction between the seismic structure of the crust and uppermost mantle between the plains on the Caribbean coast of Colombia and the mountains at the Northern Andean region. Absolute and relative travel time residuals indicate the presence of a seismically fast material in the upper mantle beneath northern Colombia; preliminary results of Pn studies show a region of relatively slow Pn velocities (between 7.8 and 7.9 km/s) underneath the Caribbean coast, contrasting with values greater than 8 km/s beneath the Central and Western cordilleras of Colombia, and the Pacific coast; receiver functions suggest a significantly thinner crust beneath the Caribbean coast, with a crustal thickness between 25 and 30 km, than beneath the Northern Andean zone at the cordilleras of Colombia, where it exceeds 40 km and reaches about 57 km at the location of Bogota. Besides the obviuos discrepancies that appear in response to different topography, we think that the seismological observations are a consequence of the presence of two very distinct slab segments beneath Colombia and contrasting behaviors of the upper plate, which correspond to Caribbean and Nazca subductions. Our seismic observations can be explained by a shallowly subducting Caribbean Plate, in the absence of an asthenospheric wedge, that steepens at about the location of the Bucaramanga nest, and a thinned continental crust that reflects an extensional component linked to oblique convergence of the Caribbean, which contrasts with the crustal thickening in the Andean Cordillera linked to crustal shortening and Nazca plate subuction. These new data are consistent with the idea of of a relatively warm Nazca slab of Neogene age which seems to have a relatively frontal convergence, and a colder, more buoyant Caribbean slab which represents an

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.

Urban Action. Under Cobblestones... The Beach!

Directory of Open Access Journals (Sweden)

Camilo Salazar Ferro

2015-07-01

Full Text Available This text was crafted by several people for the Bogotá Laboratory experimental space (LabBog; it takes its inspiration from the development of a short piece of writing that was read in the First International Forum on Urban Action, which took place in April of 2014 in Bogotá, Colombia. This manifesto demonstrates our critical position from the point of view of the loneliness of our profession as teachers with respect to the reality of the city. It has been developed through our classes as well as through the continued research that we do in the Laboratory.

Developing an Acquisition Strategy for the Colombian Navy’s New Strategic Surface Ships

Science.gov (United States)

2007-06-01

37 Departamento Nacional de Planeacion (2006), “Visión Colombia II Centenario: 2019.” Retrieved 14 May 2007 from http...40 Jefatura Oficina Planeacion A.R.C. (July 2006), Plan de Desarrollo 2007–2010, conference presented at Dirección General Marítima, Bogota...Departamento Nacional de Planeacion (2006). “Visión Colombia II Centenario: 2019”. Retrieved 14 May 2007 from http://www.dnp.gov.co/paginas_detalle.aspx?idp=888

Post appendectomy Mass (pseudomixoma peritoneal; a purpose of a case

International Nuclear Information System (INIS)

Hoyos, Juan C; Munoz, Andres

2004-01-01

A case of Pseudomyxoma Peritonei originated in a mucinous adenocarcinoma of the appendix is presented. The patient was attended at the National Cancer Institute of Bogota, Colombia. Literature is reviewed, making emphasis on the etiopathogenic and pathology aspects, and treatment modalities of this infrequent and enigmatic entity

Evaluation of Efficiency of Schoenly Trap for Collecting Adult Sarcosaprophagous Dipterans

DEFF Research Database (Denmark)

Ordonez Gloria, Alejandro

2008-01-01

Communities of adult sarcosaprophagous dipterans were evaluated using both Schoenly traps (BST) baited with rabbit carcasses and the traditional forensic methodology (TradC) in the Sabana de Bogota ́ , Colombia. During 42 sampling days, 2,726 adult dipterans were collected (2,291 by BST and 435...

Evaluation of efficiency of Schoenly trap for collecting adult sarcosaprophagous dipterans

NARCIS (Netherlands)

Ordonez, A.; Garcia, M. D.; Fagua, G.

Communities of adult sarcosaprophagous dipterans were evaluated using both Schoenly traps (BST) baited with rabbit carcasses and the traditional forensic methodology (TradC) in the Sabana de Bogota, Colombia. During 42 sampling days, 2,726 adult dipterans were collected (2,291 by BST and 435 by

MODELACIÓN HIDROLÓGICA DEL HUMEDAL DE JABOQUE – BOGOTÁ, D.C. (COLOMBIA

Directory of Open Access Journals (Sweden)

Beltrán Julio

2013-07-01

Full Text Available Se propone un modelo de simulación dinámico para explicar los procesos hidrológicosdel humedal Jaboque – Bogotá D.C., Colombia, en tres secciones con característicasfísicas y químicas particulares. El modelo incluye los caudales de entrada y salidade agua para cada una de las secciones del humedal. La modelación dinámica sebasó en ecuaciones diferenciales. Se utilizó el método Euler de integración con elprograma computacional Stella 9.1®. El comportamiento hidrológico del humedaltiene una alta dependencia de los aportes de la cuenca aferente que a su vez obedecenfundamentalmente a las condiciones climáticas de la cuenca. En el año 1992 (añoNiño la precipitación fue 432.7 mm/año con una descarga de agua estimada de lacuenca aferente de 905 225 m3/año, siendo el valor más bajo en los últimos 39 años.En el 2010 (año Niña la precipitación anual fue de 1251.3. mm, con una descargade la cuenca aferente de 2 471 634 m3/año, que corresponde al dato más alto para elmismo periodo. La comparación entre los caudales de entrada y salida del humedalJaboque muestran una diferencia bruta de 82 165 m3/mes para un total anual de 985980 m3/año. El tiempo hidráulico de retención modelado (THR se estimó en quincepara la primera sección, 36 y 42 días para la segunda y tercera sección. El promedioen el humedal fue de 93 días/año. El análisis de sensibilidad mostró que entre loslimites de 800 mm/año y 900 mm/año, valores entre los cuales oscila el promediomultianual de la precipitación, el comportamiento del THR es de 13 a 15 días/año enla primera sección, en la segunda de 32 a 36 días/año y la tercera de 38 a 43 días. Secorrobora así la relación que existe entre la precipitación y los factores morfométricosdel humedal.

[Colombia 2015 National Mental Health Survey. Study Protocol].

Science.gov (United States)

Gómez-Restrepo, Carlos; de Santacruz, Cecilia; Rodriguez, María Nelcy; Rodriguez, Viviana; Tamayo Martínez, Nathalie; Matallana, Diana; Gonzalez, Lina M

2016-12-01

The 2015 National Mental Health Survey (NMHS) is the fourth mental survey conducted in Colombia, and is part of the National System of Surveys and Population Studies for health. A narrative description is used to explain the background, references, the preparation, and characteristics of the 2015 NMHS. The 2015 NMHS and its protocol emerge from the requirements that support the national and international policies related to mental health. Together with the Ministry of Health and Social Protection, the objectives, the collection tools, the sample, and the operational plan are defined. The main objective was to obtain updated information about the mental health, mental problems and disorders, accessibility to health services, and an evaluation of health conditions. Participants were inhabitants from both urban and rural areas, over 7 years old, and in whom the comprehension of social determinants and equity were privileged. An observational cross-sectional design with national, regional and age group representativity, was used. The age groups selected were 7-11, 12-17, and over 18 years old. The regions considered were Central, Orient, Atlantic, Pacific, and Bogota. The calculated sample had a minimum of 12,080 and a maximum of 14,496 participants. A brief summary of the protocol of the 2015 NMHS is presented. The full document with all the collection tools can be consulted on the Health Ministry webpage. Copyright © 2016. Publicado por Elsevier España.

Criptococosis del sistema nervioso central (s.n.c.: revision del tema y estudio de 7 casos

Directory of Open Access Journals (Sweden)

Gabriel Toro G.

1973-01-01

Full Text Available Seven autopsy proved cases of Cryptococcosis with involvement of the CNS that were studied at the University Hospital of San Juan de Dios of Bogota, Colombia, during the last 20 years, are presented. Their clinical, diagnostic and histopathological findings are commented and the literature is reviewed.

All projects related to | Page 160 | IDRC - International Development ...

International Development Research Centre (IDRC) Digital Library (Canada)

Region: Chile, Colombia, Peru, North and Central America, South America, United Kingdom. Program: Governance and Justice. Total Funding: CA$ 548,700.00. Violence in three Latin American cities: A comparative study between Bogota, Lima, and Santiago. Project. Latin America is one of the most violent regions in the ...

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...

Characteristics of the technical parameters in the realization of computed tomography studies in pediatric patients in Bogota

International Nuclear Information System (INIS)

Triana, Gustavo; Romero, Javier; Rivero, Oscar; Sosa, Daniel; Patarroyo, Edith

2005-01-01

The use of Computed Tomography (CT) examinations for the diagnosis of common pathologies in pediatric patients has increase. This implies an increase in the radiation doses that pediatric patients received, therefore increasing the risk of secondary mortality due to cancer throughout life. In recent papers, the recommended radiation doses for pediatric patients in agreement with the concept ALARA (As Low As Reasonably Achievable) has settled down. This study evaluates the CT technical parameters of pediatric examinations in Bogota city, and review if they have been fitted with parameters recommended according to age and body weight. Materials and methods: A non-probabilistic sampling of 46 scanning tests were applied to children in six different institutions in Bogota; the technical parameters of kv and second mAs were checked of studies in abdomen, thorax and skeletal muscle system. Results: It was found that the technical parameters used in TC in children are higher of the recommended; the group of 4-year-old is the most affected by dos e of unnecessary radiation. Discussion and conclusions: The information from the protection of the radiation must be spread to the whole radiology personnel of the institutions that fulfill scanning tests of pediatric patients. ar zones that influences the wetland

Step-Up DC-DC converters

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....

Life and love in the barrios.

Science.gov (United States)

Kendall, S

1991-01-01

Although migrant pressure on metropolitan areas has begun easing in Colombia, migrants from the departments of Boyaca and Cundinamarca continue to stream into the capital city of Bogota, where they face severe hardships. In Colombia, the social conditions for rural inhabitants have been improving. Per capita income has increased, family size has decreased, and women have begun to find greater opportunities. The rate of vaccination and contraceptive prevalence are now almost the same for urban and rural populations. These changes have lessened the incentive to migrate to the city. But in Boyaca and Cundinamarca, where over-intensive farming has aggravated poverty, people continue to leave Bogota. Many of the new arrivals already have relatives or friends who help them get established. But for those who don't, life is difficult. The article tells the story of Hermencia, who left Boyaca at age 12. Now 59, Hermencia has worked as a maid most of her life, changing from job to job. She has had 6 children from 3 different fathers. Luckily for Hermencia, her patrons helped her find a permanent home, and her family has maintained a network. And none of her children ended up in the street, as did Frankie, an 18 year-old from Cundinamarca. Frankie arrived in Bogota with his father, who became the bodyguard of a drug trafficker and was subsequently killed. Frankie has lived 6 years in the streets. Frankie is known to the police for mugging and drug abuse. He has a 16 year-old girlfriend who is pregnant. This is not uncommon. Women living in immigrant barrios average 4-5 children, compared to 2-3 in other low-income areas in Bogota.

Ácidos grasos, vitamina e y rotulado nutricional de margarinas y esparcibles comercializados en Bogotá, Colombia Fatty acids, vitamin E and nutritional labeling of margarines and spreads commercialized in Bogota, Colombia

Directory of Open Access Journals (Sweden)

Lorena A Bolívar C

2010-06-01

Full Text Available INTRODUCCIÓN: en Colombia es escasa la información sobre el contenido de ácidos grasos y vitaminas en margarinas y esparcibles comercializados en el ámbito local. OBJETIVO: analizar el perfil de ácidos grasos y de vitamina E de las margarinas y esparcibles más comercializados en Bogotá, Colombia, y su situación actual de rotulado nutricional según la Resolución 0288 de 2008. MATERIALES Y MÉTODOS: en 2008 se realizó un conteo de caras de las margarinas y esparcibles más comercializados en supermercados de cadena de cinco localidades de Bogotá que incluyeron diferentes estratos socioeconómicos, y se escogieron las primeras diecisiete marcas comerciales y tres marcas propias para el estudio. De cada producto se tomaron y analizaron cinco repeticiones, una por localidad, entre agosto y noviembre de 2008. RESULTADOS: los ácidos grasos mayoritarios son palmítico, oleico y linoleico, y cuatro productos son fuente de ácidos grasos trans (4,4 g y 6,9 g/100 g. El contenido de vitamina E varía de 2,3 mg a 39,9 mg/100 g de producto. De 74,3% a 96,2% de los nutrientes de declaración obligatoria son efectivamente declarados en la etiqueta de los productos analizados. RESULTADOS: 91% de las margarinas y esparcibles más comercializados en cinco localidades de Bogotá en agosto de 2008 es libre de ácidos grasos trans (INTRODUCTION: information on the content of fatty acids and vitamins in margarines and spreads locally commercialized in Colombia is scarse. OBJECTIVE: analyze the fatty acids and vitamin E profile in margarines and spreads most commercialized in Bogotá, Colombia and its current nutritional labeling under Resolution 0288 of 2008. MATERIALS AND METHODS: a counting of labels of margarines and spreads most commercialized in chain supermarkets of five localities in Bogotá that included different socio-economical strata, was made. The first seventeen trademarks and three study brand marks were chosen for the study. Five samples

A resonant dc-dc power converter assembly

OpenAIRE

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...

Direct Commercial and Foreign Military Sales: Chemical Defense Equipment, an Introductory Brochure

Science.gov (United States)

1991-06-01

60128 CGHCH CM ______________Fax: (86] (028)583-520 COLOMBIA Bogota Tel: [57](1)285-1300/1688 Telex: 44843 ______________Fax: (5711 (1)288-5687...CONSULATES Palermo Tel: (39](91)343-532 Telex: 910313 USA CON I Commercial Section: (39] (91)346-036, 345-1923 Fax: (39] (91)343-546 Florence Tel: [39

Therapeutic Change in Colombian Families Dealing with Violence: Therapists, Clients, and Referring Systems in Conversation

Science.gov (United States)

Ripoll-Nunez, Karen; Villar-Guhl, Carlos Felipe; Villar-Concha, Eduardo

2012-01-01

There is a gap in the Marriage and Family Therapy literature regarding clients', therapists', and family judges' theories of change in relational therapy for family violence. We conducted in-depth interviews with eleven court-referred families, their therapists, and two family judges in Bogota, Colombia. Interviews focused on their expectations of…

77 FR 44717 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Foreign...

Science.gov (United States)

2012-07-30

....L. DE C.V., Mexico, Distrito Federal, Mexico; DOB 26 Jul 1950; POB Mexico, D.F., Mexico; citizen Mexico; nationality Mexico (individual) [SDNTK] 3. BERNAL BERNAL, Liliana, c/o COLPRETINAS LTDA., Bogota...; c/o DISCO S.A., Cota, Cundinamarca, Colombia; c/o JESBEL Y CIA. S. EN C., Cota, Cundinamarca...

The privatization of EEB: From cash drain to major contributor

International Nuclear Information System (INIS)

Cavaliere, Christianne; Larsen, Erik R.; Dyner, Isaac

2007-01-01

In this paper we describe the successful part-privatization of Empresa de Energia de Bogota (EEB), the city-owned electricity company in Bogota, Colombia. We describe the reason, the preparation and the actual sale process as well as the outcome following the part-privatization. EEB went from being a company on the edge of bankruptcy to one of the most financially secure electricity companies in South America. We also place the case in relation to the standard views on direct foreign investment and their social benefit. Finally, we aim to generalize the experience to see what other organizations in a similar position can learn

The caves of Cunday (Colombia, South America)

NARCIS (Netherlands)

Hammen, van der Th.; Nelson, H.W.

1955-01-01

A short time ago rumors reached Bogota that a big cavesystem had been discovered by some farmers in the southwest of the department of Tolima, between the villages of Cunday and Purificación. This region belongs morphologically and geologically to the Eastern Cordillera, and forms the westernmost

Step-Up DC-DC converters

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...

EVALUACIÓN DEL IMPACTO PRESUPUESTAL DE UNA NUEVA TÉCNICA DIAGNÓSTICA PARA LA VIGILANCIA EPIDEMIOLÓGICA DE LA ENFERMEDAD RESPIRATORIA AGUDA EN UN LABORATORIO DE REFERENCIA EN BOGOTÁ, COLOMBIA

Directory of Open Access Journals (Sweden)

Liliana Patricia Díaz Cuevas

2016-04-01

Full Text Available

Objetivo: Evaluar el impacto presupuestal de introducir una nueva técnica diagnóstica para la vigilancia epidemiológica en la enfermedad respiratoria aguda en un laboratorio de referencia en Bogotá, Colombia.

Materiales y métodos: Estudio de impacto presupuestario desde la perspectiva del tercero pagador, para la patología de ERA con criterios de Infección respiratoria aguda grave (IRAG, con un horizonte temporal de cinco años (2013-2017, determinando los costos directos de las pruebas y su impacto en la población.

Resultados: Al introducir la nueva técnica en forma progresiva hasta llegar al 75%, a los cinco años, el impacto fue un incremento del presupuesto en un 27% ($203.463.717 más que con el costo de las pruebas actuales. El análisis de sensibilidad univariado, modificando la variable porcentaje de introducción de la nueva prueba, permitió establecer que a un menor porcentaje de inversión de las pruebas actuales y un porcentaje mayor de introducción de la nueva prueba, el impacto en el costo del presupuesto al término de los cinco años será mayor.

Conclusiones: La introducción de la nueva técnica diagnóstica hasta el 75% en el horizonte temporal de cinco años, tendrá un impacto del 27% en el presupuesto, comparado con la utilización de las pruebas actuales. La ampliación del perfil viral y el acercamiento a la realidad, permitirá formular nuevas políticas públicas en el tratamiento y pronóstico de la ERA en la población de Bogotá.

BUDGET IMPACT ASSESSMENT OF A NEW DIAGNOSTIC TECHNIQUE FOR SURVEILLANCE OF ACUTE RESPIRATORY DESEASE IN A LABORATORY REFERENCE IN BOGOTA-COLOMBIA

ABSTRACT

Objective: To evaluate the budget impact of the introduction of a new diagnostic test for epidemiological surveillance for acute respiratory illness in a reference

75 FR 23571 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

Science.gov (United States)

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...

Respiratory syncytial virus, adenoviruses, and mixed acute lower respiratory infections in children in a developing country.

Science.gov (United States)

Rodríguez-Martínez, Carlos E; Rodríguez, Diego Andrés; Nino, Gustavo

2015-05-01

There is growing evidence suggesting greater severity and worse outcomes in children with mixed as compared to single respiratory virus infections. However, studies that assess the risk factors that may predispose a child to a mixture of respiratory syncytial virus (RSV) and adenoviral infections, are scarce. In a retrospective cohort study, the study investigated the epidemiology of RSV and adenovirus infections and predictors of mixed RSV-adenoviral infections in young children hospitalized with acute lower respiratory infection in Bogota, Colombia, South America, over a 2-year period 2009-2011. Of a total of 5,539 children admitted with a diagnosis of acute lower respiratory infection, 2,267 (40.9%) who were positive for RSV and/or adenovirus were selected. Out the total number of cases, 1,416 (62.5%) infections occurred during the 3-month period from March to May, the first rainy season of Bogota, Colombia. After controlling for gender, month when the nasopharyngeal sample was taken, and other pre-existing conditions, it was found that an age greater than 6 months (OR:1.74; CI 95%:1.05-2.89; P = 0.030) and malnutrition as a comorbidity (OR:9.92; CI 95%:1.01-100.9; P = 0.049) were independent predictors of mixed RSV-adenoviral infections in the sample of patients. In conclusion, RSV and adenovirus are significant causes of acute lower respiratory infection in infants and young children in Bogota, Colombia, especially during the first rainy season. The identified predictors of mixed RSV-adenoviral infections should be taken into account when planning intervention, in order to reduce the burden of acute lower respiratory infection in young children living in the country. © 2015 Wiley Periodicals, Inc.

Gout. Radiological aspects

International Nuclear Information System (INIS)

Restrepo Suarez, Jose Felix; Pena Cortes, Mario; Rondon Herrera, Federico; Iglesias Gamarra, Antonio; Calvo Paramo, Enrique

2000-01-01

In this paper we reviewed the clinical and radiological aspects of gout, showing the most frequent radiological findings that can guide to the correct diagnosis of the disease. The cases that we presented here have been analyzed for many years in our rheumatology service, Universidad Nacional de Colombia, Hospital San Juan de Dios, Bogota

Study of the mobilization of pollutants in soils of the Bogota Savanna - phase 1, Heavy Metals

International Nuclear Information System (INIS)

Gonzalez, Luz Myrian; Vargas Zarate, Orlando

1997-01-01

In this study the soils contamination of the Bogota Savanna was evaluated by heavy metals, that they have importance to be this the area of population's of the country bigger density, where the use of the soils has suffered changes in the last years that have affected its properties, as consequence of the not controlled growth of the urban area, of the industrialization and of the agricultural use not planned. As a first stage toward the risk evaluation for the presence of metals weighed in the soils of the Bogota Savanna, the concentrations of cadmium, cobalt, chromium, copper, manganese, nickel, lead, zinc, molybdenum, arsenic and mercury were measured. It was also measured the movilizable fraction and the mobile fraction, that is to say, the quantity of metals that can be taken by the roots of the plants or that it can be leached toward the water bodies. Equally, the soils of the Savanna were characterized in an area of the plane part that covers 800 km 2 , as for the physical and chemical properties that can affect the retention and mobilization of heavy metals. The results obtained shows elements, that will allow in a future to develop mobilization and transport models, adapted for our specific conditions and to make an risks evaluation for the population's health, foods consumption on these soils or for the possibility of contamination of the underground waters. The obtained data of levels of heavy metals and other properties of the soils will serve as base for future studies of the conditions of the Savanna soils and for the establishment of standard of quality in our country. During 1997 it plans to enlarge the study area to 1200 km 2 and to begin the sampling and analysis of the soils. In the first phase of the study were found levels of heavy metals that overcome the world averages especially cadmium, cobalt, nickel, lead and zinc and in some cases chromium and mercury, levels that put in evidence the existence an ecological risk and for the population

Heat island and spatio-temporal changes of temperature in the city of Bogota

International Nuclear Information System (INIS)

Angel, L; Ramirez, A; Dominguez, E.

2010-01-01

The planet Earth, as a whole, has experienced a warming process caused principally by the accumulation of atmospheric greenhouse gases. Otherwise, it has been well demonstrated that thermic islands exist inside of cities, essentially as a result of the replacement of forest areas with urban materials such as asphalt, concrete, bricks, etc. Based on this foundation, this research evaluated the minimum, median and maximum temperature changes that occurred in the city of Bogota over the last 40 years. This research makes evident the presence of a heat island 3o Cover the periphery median temperature in most of the city. There were also periods with increases and decreases in city temperatures, not affected in its main tendency by the Nino Phenomena which in contrast affected the periphery.

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

Colombia.

Science.gov (United States)

1986-10-01

This report of background notes for Colombia concentrates on political history, but also summarizes geography, people, economy, defense and foreign relations. Colombia, linking Panama to the northwest tip of South America, has 26.5 million people, growing at 1.3% per year, expected to be the third most populous nationon the continent soon. Infant mortality rate is 65/1000 and life expectancy is 62 years. Literacy is reported at 80% although less than 40% of children complete 2.5 years of school. Geographically, Colombia has flat coastal areas, several mountain ranges, highlands and hot eastern plains. 70% of the population live in cities. There are 2 major political parties, in existence since the early 19th century. Recently there have been violent inter-party differences, punctuated by even more contentious guerrilla attacks. Colombia possesses resources of oil, gas coal, nickel, gold, emeralds, platinum, iron. Agricultural products are dominated by coffee, but also include a wide variety of tropical and temperate grains, fruits, vegetables, dairy and meat products, timber and flowers.

Impact of payroll taxes for small shoe manufacturing enterprises profit generation in Bogota city 15th district

Directory of Open Access Journals (Sweden)

José Armando Hernández Bernal

2016-04-01

Full Text Available In this paper we illustrate the financial difficulties that payroll taxes would impose on small shoe manufacturing enterprises in Bogota City 15th district and how this would impose some restrictions for firms profit generation, when such contributions turns out to be a fixed cost. We present a brief on the legal framework as well as an econometric exercise that shows the relations between labor costs and profit generation for the footwear industry in the 15th urban district of Bogotá city.

Family of multiport bidirectional DC-DC converters

NARCIS (Netherlands)

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

Observatorio de Política Internacional I. COLOMBIA - Colombia. Crónica de un proceso de paz fracasado

OpenAIRE

Neira Fernández, Enrique

2007-01-01

Observatorio de Política Internacional I. COLOMBIA (Neira Fernández, Enrique) RECIENTES Año 2008 Colombia. Cerca el fin del paramilitarismo Colombia. Cerca el fin de las Farc Colombia. Conflicto armado y desarrollo humano Colombia. Política exterior Colombia. Inicia el 2008 con buen pie Año 2007 Colombia. Tras las pasadas elecciones Colombia. El espectro de las próximas elecciones Colombia. La garrocha de Uribe Colombia. III Parapolíticos Colombia. II...

Outlook of the process of storage of oncology drugs from the logistic operator in Colombia

Directory of Open Access Journals (Sweden)

Pedro Vicente Sánchez-Calvera

2014-05-01

Full Text Available This article mainly on the problem of  storage of oncology drugs, which is an important element in the supply chain, applied in the context of warehouse management of oncology drugs, in the logistics operator and providers of health services institutions (IPS for its acronym in Spanish of Bogotá DC and in the contex of a macro project "Methodological proposal for the definition of policies , rules of negotation and coordination in supply management of oncology drugs in Colombia," funded by Colciencias and the Universidad Nacional of Colombia. This article presents the current situation of oncology drugs, marking a characterization, diagnosis and identification and startegies evaluated under different scenarios. Finally, it is presented a proposal of improvement applied tranversely to storage processes including labels such as just in Time and the application of information and communication technologies (ICT.

Instituto de Asuntos Nucleares. Report of Activities 1989

International Nuclear Information System (INIS)

1989-01-01

It is a summary of the technical activities carried out by the Instituto de Asuntos Nucleares, Bogota, Colombia, during 1989. It includes activities in topics as: research projects, transfer of technology, scientific information, qualification and training programs, mainly, which were done in areas like: agriculture, industrial applications, medicine, radiation protection, hydrology, nuclear technology development, radiochemistry and physics, among others

Colombian Lay People's Willingness to Forgive Different Actors of the Armed Conflict: Results from a Pilot Study

Science.gov (United States)

Lopez-Lopez, Wilson; Pineda Marin, Claudia; Murcia Leon, Maria Camila; Perilla Garzon, Diana Carolina; Mullet, Etienne

2012-01-01

A pilot study examined lay people's willingness to forgive acts that were committed by actors of the armed conflicts in Colombia. The participants (100 persons living in Bogota) were shown vignettes describing cases in which a member of the guerilla or a member of the former paramilitary forces asks for forgiveness to a victim's family, and were…

Design and Testing of Boost Type DC/DC Converter for DC Motor Control Applications

OpenAIRE

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...

Enfermedad cerebrovascular en Colombia Cerebrovascular disease in Colombia

Directory of Open Access Journals (Sweden)

Federico A Silva

2006-10-01

Full Text Available Introducción: la enfermedad cerebrovascular constituye un problema de salud pública mundial. En Colombia es la cuarta causa de muerte en la población adulta y genera una alta discapacidad en estos pacientes. Objetivo: describir algunos resultados obtenidos por el grupo de Ciencias Neurovasculares de la Fundación Cardiovascular de Colombia. Desarrollo y conclusiones: la enfermedad cerebrovascular es una entidad con una alta prevalencia en la población colombiana y genera discapacidad mental, motora y del lenguaje. Es necesaria la implementación de unidades de cuidado neurovascular con personal entrenado, protocolos definidos, tratamientos adecuados y tecnología de punta. En Colombia deben imponerse este tipo de unidades dentro del cuidado básico de los pacientes para disminuir la morbilidad, mortalidad y discapacidad generada en estos pacientes. La Fundación Cardiovascular de Colombia es pionera en la implementación de este tipo de cuidados.Introduction: cerebrovascular disease constitutes a worldwide public health problem. In Colombia, it is the fourth leading cause of death in the adult population and generates high disability in these patients. Objective: to describe some results obtained by the Neurovascular Sciences group from the Colombian Cardiovascular Foundation. Development and conclusions: cerebrovascular disease has a high prevalence in the Colombian population and generates mental, motor, and language disabilities. The implementation of neurovascular care units with trained personnel, defined protocols, adequate treatments and high technology, are necessary. This kind of units must be imposed in Colombia as a basic care for these patients in order to decrease morbidity, mortality and disability. The Colombian Cardiovascular Foundation is pioneer in the implementation of these care units.

Lightning magnetic field measuring system in Bogota

OpenAIRE

Escobar Alvarado, Oscar Fernardo

2013-01-01

This thesis presents the configuration and performance of a lightning radiated electromagnetic field measuring system in Bogotá Colombia. The system is composed by both magnetic and electric field measuring systems working as separated sensors. The aim of the thesis is the design and construction of a Magnetic Field Measuring System and the implementation of a whole lightning measuring system in Bogotá. The theoretical background, design process, construction and implementation of the system ...

Generation and evaluation of an indicator of the health system's performance in maternal and reproductive health in Colombia: An ecological study.

Science.gov (United States)

Pinzón-Flórez, Carlos Eduardo; Fernandez-Niño, Julian Alfredo; Cardenas-Cardenas, Luz Mery; Díaz-Quijano, Diana Marcela; Ruiz-Rodriguez, Myriam; Reveiz, Ludovic; Arredondo-López, Armando

2017-01-01

To generate and evaluate an indicator of the health system's performance in the area of maternal and reproductive health in Colombia. An indicator was constructed based on variables related to the coverage and utilization of healthcare services for pregnant and reproductive-age women. A factor analysis was performed using a polychoric correlation matrix and the states were classified according to the indicator's score. A path analysis was used to evaluate the relationship between the indicator and social determinants, with the maternal mortality ratio as the response variable. The factor analysis indicates that only one principal factor exists, namely "coverage and utilization of maternal healthcare services" (eigenvalue 4.35). The indicator performed best in the states of Atlantic, Bogota, Boyaca, Cundinamarca, Huila, Risaralda and Santander (Q4). The poorest performance (Q1) occurred in Caqueta, Choco, La Guajira, Vichada, Guainia, Amazonas and Vaupes. The indicator's behavior was found to have an association with the unsatisfied basic needs index and women's education (β = -0.021; 95%CI -0031 to -0.01 and β 0.554; 95%CI 0.39 to 0.72, respectively). According to the path analysis, an inverse relationship exists between the proposed indicator and the behavior of the maternal mortality ratio (β = -49.34; 95%CI -77.7 to -20.9); performance was a mediating variable. The performance of the health system with respect to its management of access and coverage for maternal and reproductive health appears to function as a mediating variable between social determinants and maternal mortality in Colombia.

Generation and evaluation of an indicator of the health system's performance in maternal and reproductive health in Colombia: An ecological study.

Directory of Open Access Journals (Sweden)

Carlos Eduardo Pinzón-Flórez

Full Text Available To generate and evaluate an indicator of the health system's performance in the area of maternal and reproductive health in Colombia.An indicator was constructed based on variables related to the coverage and utilization of healthcare services for pregnant and reproductive-age women. A factor analysis was performed using a polychoric correlation matrix and the states were classified according to the indicator's score. A path analysis was used to evaluate the relationship between the indicator and social determinants, with the maternal mortality ratio as the response variable.The factor analysis indicates that only one principal factor exists, namely "coverage and utilization of maternal healthcare services" (eigenvalue 4.35. The indicator performed best in the states of Atlantic, Bogota, Boyaca, Cundinamarca, Huila, Risaralda and Santander (Q4. The poorest performance (Q1 occurred in Caqueta, Choco, La Guajira, Vichada, Guainia, Amazonas and Vaupes. The indicator's behavior was found to have an association with the unsatisfied basic needs index and women's education (β = -0.021; 95%CI -0031 to -0.01 and β 0.554; 95%CI 0.39 to 0.72, respectively. According to the path analysis, an inverse relationship exists between the proposed indicator and the behavior of the maternal mortality ratio (β = -49.34; 95%CI -77.7 to -20.9; performance was a mediating variable.The performance of the health system with respect to its management of access and coverage for maternal and reproductive health appears to function as a mediating variable between social determinants and maternal mortality in Colombia.

Emigración e inmigración internacional en el área metropolitana de Bogotá (Colombia

Directory of Open Access Journals (Sweden)

John Harold Córdoba Aldana

2016-08-01

Full Text Available This article presents some results of an investigation about the relation between international mobility and residential trends in the Colombian capital. It aims to analyze the spatial dynamics of international emigration and immigration in Bogota. The research analyzes two population censuses (1993 and 2005 and a biographical survey carried out in the metal research program during 2009-2010. This article is a gateway to understanding the residential dynamics and urban changes from the perspective of international migration in the Bogota metropolitan area.

ConstitutionalJustice: Cases of Protection of Freedom and Personal Security in Colombia

Directory of Open Access Journals (Sweden)

Viridiana Molinares Hassan

2014-07-01

Full Text Available In this paper we present the results of an investigation about judicial protection of freedom and personal security granted by the Constitutional Court (cc of Colombia, with a comparative analysis between the period 1992-2001, to which governments have appointed period of postconstitucionales, which coincides with the issuance of the 1991 Constitution, and the creation of constitutional jurisdiction, and the period 2002-2010, during which it ran the Democratic Security Policy (dsp as a government policy proposal by former president Álvaro Uribe, whose aim was to achieve peace through the declaration of war to the guerrilla group Revolutionary Armed Forces of Colombia (farc. Our interest is to show that the protection of freedom and personal security as the basis of the Constitutional (ec finds in the cc his greatest guarantor, even against closing courts in other jurisdictions that are still rooted in the failed legal positivist paradigm, ignoring the postulates of neoconstitutionalism dc sufficiently developed from a process of creative interpretation and decision-making. This coupled with the importance for the branches of power and knowledge associated scope of freedom and personal security developed by the cc in the difficult context of irregular warfare that exists in Colombia, yet it is, for universal constitutionalism, an example of the development of legal guarantor in the context of current constitutionalism.

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...

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...

IGBT Based DC/DC Converter

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.

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...

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.

Modeling of primary production of phytoplankton in the wetland Jaboque, Bogotá D.C.

Directory of Open Access Journals (Sweden)

Julio Eduardo Beltrán Vargas

2016-02-01

Full Text Available A dynamic simulation model is presented to explain the general behavior of the  primary production of phytoplankton in the wetland Jaboque - Bogota, Colombia, in three sections with differential physical and chemical characteristics. The model takes into account the physicochemical variables, the basin area, depth, annual rainfall, water temperature, pH and concentration of chlorophyll _a. The dynamic modeling is based on differential equations and the Euler integration method is used, the modeling was developed using Stella 9.1® computer program. The model allows quantifying the primary production of phytoplankton in wetland Jaboque from chlorophyll _a monthly average concentration for each section. The results of the Ppf modeling show that Ppf concentration variations  in each section of the wetland follow a reverse pattern to the bimodal behavior of precipitation. A high degree of correspondence between the values of chlorophyll_a Ppf field and modeled in the following manner r2 = 0.86 for the first section and r2 = 0.86 and r2 = 0.79 for the remaining sections was found. Error determination was 0,57 relative to the first section and 0,35; 0,46, indicating that the results are not overstated. The model shows in general terms the functional aspects of behavior Ppf and its relation to the process of eutrophication, and it allows recommendations for the management and restoration of wetlands.

El papel de los profesionales en centros de atención en drogas en ambulatorios de la ciudad de Bogotá, Colombia Papéis de profissionais, em centros de atenção ambulatorial em drogas, na cidade de Bogotá, Colômbia Roles of professionals in drug outpatient care centers, in the city of Bogota, Colombia

Directory of Open Access Journals (Sweden)

Luz Patricia Díaz Heredia

2010-06-01

ço dentro da equipe de atenção aos usuários de drogas.The aim of this descriptive, cross-sectional study, developed with 93 professionals, was to characterize the roles of the professionals who were working in the drug addiction outpatient centers of the city of Bogota, Colombia. The results showed that psychologists were the predominant professionals (38%, followed by occupational therapists (34%. Nurses corresponded to 8% of the professionals, with their roles predominantly in the aspects of health promotion and self care (100%, in the administrative area (43% and in prevention (57% and very little in rehabilitation and social rehabilitation (14%. The roles of the professionals agreed with the expected activities of the different professions, with the exception of the occupational therapists. It is considered that nurses need to gain more space within the team to focus on drug users.

Triceps and Subscapular Skinfold Thickness Percentiles and Cut-Offs for Overweight and Obesity in a Population-Based Sample of Schoolchildren and Adolescents in Bogota, Colombia

Science.gov (United States)

Ramírez-Vélez, Robinson; López-Cifuentes, Mario Ferney; Correa-Bautista, Jorge Enrique; González-Ruíz, Katherine; González-Jiménez, Emilio; Córdoba-Rodríguez, Diana Paola; Vivas, Andrés; Triana-Reina, Hector Reynaldo; Schmidt-RioValle, Jacqueline

2016-01-01

The assessment of skinfold thickness is an objective measure of adiposity. The aims of this study were to establish Colombian smoothed centile charts and LMS L (Box–Cox transformation), M (median), and S (coefficient of variation) tables for triceps, subscapular, and triceps + subscapular skinfolds; appropriate cut-offs were selected using receiver operating characteristic (ROC) analysis based on a population-based sample of children and adolescents in Bogotá, Colombia. A cross-sectional study was conducted in 9618 children and adolescents (55.7% girls; age range of 9–17.9 years). Triceps and subscapular skinfold measurements were obtained using standardized methods. We calculated the triceps + subscapular skinfold (T + SS) sum. Smoothed percentile curves for triceps and subscapular skinfold thickness were derived using the LMS method. ROC curve analyses were used to evaluate the optimal cut-off point of skinfold thickness for overweight and obesity, based on the International Obesity Task Force definitions. Subscapular and triceps skinfolds and T + SS were significantly higher in girls than in boys (p < 0.001). The ROC analysis showed that subscapular and triceps skinfolds and T + SS have a high discriminatory power in the identification of overweight and obesity in the sample population in this study. Our results provide sex- and age-specific normative reference standards for skinfold thickness values from a population from Bogotá, Colombia. PMID:27669294

Triceps and Subscapular Skinfold Thickness Percentiles and Cut-Offs for Overweight and Obesity in a Population-Based Sample of Schoolchildren and Adolescents in Bogota, Colombia

Directory of Open Access Journals (Sweden)

Robinson Ramírez-Vélez

2016-09-01

Full Text Available The assessment of skinfold thickness is an objective measure of adiposity. The aims of this study were to establish Colombian smoothed centile charts and LMS L (Box–Cox transformation, M (median, and S (coefficient of variation tables for triceps, subscapular, and triceps + subscapular skinfolds; appropriate cut-offs were selected using receiver operating characteristic (ROC analysis based on a population-based sample of children and adolescents in Bogotá, Colombia. A cross-sectional study was conducted in 9618 children and adolescents (55.7% girls; age range of 9–17.9 years. Triceps and subscapular skinfold measurements were obtained using standardized methods. We calculated the triceps + subscapular skinfold (T + SS sum. Smoothed percentile curves for triceps and subscapular skinfold thickness were derived using the LMS method. ROC curve analyses were used to evaluate the optimal cut-off point of skinfold thickness for overweight and obesity, based on the International Obesity Task Force definitions. Subscapular and triceps skinfolds and T + SS were significantly higher in girls than in boys (p < 0.001. The ROC analysis showed that subscapular and triceps skinfolds and T + SS have a high discriminatory power in the identification of overweight and obesity in the sample population in this study. Our results provide sex- and age-specific normative reference standards for skinfold thickness values from a population from Bogotá, Colombia.

Composición Química del Aceite de Almendras producidas por el Árbol Olleto (Lecythis minor DC) Chemical Composition of Almond Oil obtained from Olleto Trees (Lecythis minor DC)

OpenAIRE

Jennifer J Lafont; Elder A Calle; Luis C Durango

2013-01-01

Se comparan dos métodos de extracción del aceite a partir de las almendras del árbol conocido en el norte de Colombia con el nombre de olleto (Lecythis minor DC). Se analizó su composición química y se determinaron algunas propiedades fisicoquímicas. También se realizó el análisis proximal a la torta y la harina y se determinó la presencia de metales en la almendra. Para extraer el aceite, las almendras fueron trituradas y sometidas a procesos de prensado y extracción con solvente. La composi...

Interaction of the heavy metals (Cr +6, Cd, Pb, Ni) between the silt and the water column in the case study of Bogota River

International Nuclear Information System (INIS)

Pinzon U, L.F.; Rodriguez, J.A.; Giraldo, E.

1993-01-01

For the present study the Bogota River it uses as framework, this river has a course of 255 km., in it pathway through 26 municipalities, including the Western area of the District Capital (Bogota). In the District Capital area, some significant sampling points were founded, due to their localization on the bed and that industrial activities of grateful polluting function are developed. Silt samples were extracted and it dilutes for chemical-physical analysis and study to scale; these samples were implanted in columns or reactors; one of characteristic totally anaerobic and another of characteristic aerobic. Of equal forms it procedure is repeated, but replacing the river water for dilution water; every third day the extracted samples are been about agreement with the metal to analyze Chromium IV for the waters, Total Chromium for the silts, Cadmium, Lead and Total Nickel in the column of water and silts to be analyzed by means of Absorption Atomic Spectrophotometry. The object is the one of establishing that exchange type is presented between the polluted water and the water free of contaminants

75 FR 60602 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

Science.gov (United States)

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...

75 FR 38943 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-30, DC...

Science.gov (United States)

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...

Determination of Magnitude and Location of Earthquakes With Only Five Seconds of a Three Component Broadband Sensor Signal Located Near Bogota, Colombia Using Support Vector Machines

Science.gov (United States)

Ochoa Gutierrez, L. H.; Vargas Jiménez, C. A.; Niño Vasquez, L. F., Sr.

2017-12-01

Early warning generation for earthquakes that occur near the city of Bogotá-Colombia is extremely important. Using the information of a broadband and three component station, property of the Servicio Geológico Colombiano (SGC), called El Rosal, which is located very near the city, we developed a model based on support vector machines techniques (SVM), with a standardized polynomial kernel, using as descriptors or input data, seismic signal features, complemented by the hipocentral parameters calculated for each one of the reported events. The model was trained and evaluated by cross correlation and was used to predict, with only five seconds of signal, the magnitude and location of a seismic event. With the proposed model we calculated local magnitude with an accuracy of 0.19 units of magnitude, epicentral distance with an accuracy of about 11 k, depth with a precision of approximately 40 km and the azimuth of arrival with a precision of 45°. This research made a significant contribution for early warning generation for the country, in particular for the city of Bogotá. These models will be implemented in the future in the "Red Sismológica de la Sabana de Bogotá y sus Alrededores (RSSB)" which belongs to the Universidad Nacional de Colombia.

75 FR 6160 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

Science.gov (United States)

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...

Edentulism and dental prostheses in the elderly: impact on quality of life measured with EuroQol--visual analog scale (EQ-VAS).

Science.gov (United States)

Cano-Gutiérrez, Carlos; Borda, Miguel G; Arciniegas, Antonio J; Borda, Claudia X

2015-01-01

The objective of this study was to measure the impact of edentulism and dental prostheses on quality of life (QOL) in older adults in Bogota, Colombia. Edentulism is a frequent condition in older adults and has great impact on their QOL. No epidemiological data are currently available on edentulism among older adults in Colombia. Data were obtained from the SABE-Bogota study, a cross-sectional study conducted in 2012, and used to analyze the EQ-VAS (Visual Analog Scale) from the EuroQol instrument to measure the perception of quality of life (QOL) in relation to edentulism. The study included 2,000 individuals over 60 years old. The Spearman-Rho correlation was used to analyze the correlation between EQ-VAS and edentulism. Chi-Square, ANOVA and t-test were used to study the differences in EQ-VAS scores between edentulous and healthy subjects. Statistical significance was set at peducation were related to edentulism. Individuals with fewer teeth and dental prostheses had lower EQ-VAS scores (pmeasuring the perception of QOL in dental health scenarios. Edentulism significantly affects QOL in older adults and the use of dental prosthesis does not improve the perception of QOL.

75 FR 61989 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-8-31, DC-8-32, DC-8-33, DC-8-41...

Science.gov (United States)

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...

[Case study: school meals' management in Santiago de Cali and Bogota].

Science.gov (United States)

Díaz, Mónica del Pilar; Montoya, Iván A; Montoya, Luz A

2011-10-01

This research was aimed at ascertaining the state's role regarding hunger and how it manages to combat this matter; a food security program in two Colombian cities was thus assessed (i.e. school meals' provision in Cali and Bogota). A qualitative approach was adopted; documentary analysis, participant observation and in-depth interviews with various actors for both selected cases were used as data collection techniques. It was found that several measures taken in this area were not covered by regulatory principles aimed at covering all the dimensions of food security. Serious weaknesses in school meals' management in Cali were associated with a weak environment regarding the fight against hunger. School meals' management in Bogotá was aimed at recognizing the right to food as being supported by an institutional process where the issue of reducing hunger has become a firm purpose. School meals' program management was associated with the characteristics of its product, thereby affecting the program and the population's food and nutritional status; state management thus becomes another dimension of food security.

Economic geology of the Zipaquira quadrangle and adjoining area, Department of Cundinamarca, Colombia

Science.gov (United States)

McLaughlin, Donald H.; Arce Herrera, Marino

1970-01-01

At least four evaporite sequences are interbedded with Cretaceous strata in the Bogotga area of the Cordillera Oriental of Colombia. The easternmost and oldest evaporite interval is of probable Berriasian-Valanglnian age; the next oldest is of probable late Barremian-early Aptian age, and is followed by a possible late Aptian sequence. The westernmost and best known sequence is Turonian-early Coniacian in age, in the Sabana de Bogota. This youngest sequence contains the thickest known salt deposits and is probably the most widespread geographically. Three gypsum deposits of probable Barremian-Valanginian age are in the eastern part of the area under investigation. These deposits may have been leached from former salt accumulations. No other evaporites are exposed, but numerous brine springs are known, That the sources of these brines are neither deep not distant is suggested by the generally high concentrations, of the brines, the local presence of rute (leached salt residue), and the commonly significant amounts of H2S gas emitted at these springs. The rock salt exposed in three accessible mines commonly has a characteristic lamination caused by alternating layers of relatively pure halite and very argillaceous halite. Ubiquitously scattered throughout all salt deposits are small clasts of black, commonly pyritic, marly claystone. This lithology is also present as large claystone bodies conformably interbedded in the salt strata. Anhydrite is rare and is apparently more abundant at the Zipaquira mine that at the Nemocon and Upin mine. Paleontologic evidence in the Sabana de Bogota demonstrates that the salt-claystone series, hematite impregnated strata, and carbonaceous to locally coaly claystone are coeval. The salt-claystone facies may have been deposited in shallow evaporite pans that were separated within the overall evaporite interval by barriers on which the locally hematitic strata were deposited. The carbonaceous facies may also have formed in barrier

Multi Bus DC-DC Converter in Electric Hybrid Vehicles

Science.gov (United States)

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.

Step-Up DC-DC Power Converter

DEFF Research Database (Denmark)

2015-01-01

The present invention relates to a step-up DC-DC power converter which comprises a primary side circuit and a secondary side circuit coupled through a galvanic isolation barrier. The primary side circuit comprises a positive and a negative input terminal for receipt of an input voltage and an input...... being charged from the input voltage and discharged to the output capacitor through the galvanic isolation barrier in accordance with a switch control signal to produce the converter output voltage. The step-up DC-DC power converter comprises an electrical short-circuit connection across the galvanic...

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.

Early Oscillation Detection for DC/DC Converter Fault Diagnosis

Science.gov (United States)

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.

Properties of Seven Colombian Woods.

Science.gov (United States)

1981-01-01

differences. 1971. AIgunas propiedades fisicas y mecanicas de tres Maderas Colom- Cuangare and sande had the lowest bianas. Universidad Distrital "Francisco...Jose De Caldas" Instituto de and highest figures, respectively, for Investigaciones y Proyectos Forestales y Madereros. Bogota, Colombia. bending...to 45 pounds per 1970. Estudio de preinversion para el desar- cubic foot. Basic specific gravity from this study rollo forestal de la Guyana

Prevalence of the Metabolic Syndrome in Latin America and its association with sub-clinical carotid atherosclerosis: the CARMELA cross sectional study

OpenAIRE

Torres Marta; Vinueza Raul; Boissonnet Carlos P; Silva Honorio; Champagne Beatriz; Schargrodsky Herman; Escobedo Jorge; Hernandez Rafael; Wilson Elinor

2009-01-01

Abstract Background Metabolic syndrome increases cardiovascular risk. Limited information on its prevalence in Latin America is available. The Cardiovascular Risk Factor Multiple Evaluation in Latin America (CARMELA) study included assessment of metabolic syndrome in 7 urban Latin American populations. Methods CARMELA was a cross-sectional, population-based, observational study conducted in Barquisimeto, Venezuela; Bogota, Colombia; Buenos Aires, Argentina; Lima, Peru; Mexico City, Mexico; Qu...

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

Social responsability of the Bogota companies and their relation to employement and poverty

Directory of Open Access Journals (Sweden)

Adriana Patricia López Velázquez

2006-07-01

Full Text Available This article shows the main results , conclusions and recommendations from two researches about Entrepreneurial Social Responsibility (RSE, and its relation to poverty and employment in the specific case of Bogotá. These results were obtained from a field work and literature revision about RSE, both nationally and internationally. It is worth noting that most of the Bogota companies do not know or do not have any interest in RSE, for them RSE implies high costs and little economic revenue. Out of the total of companies, only 1,3% have participated in programs to reduce poverly applied by district administration, where the common points of public and private investmetl have been education, nutrition and housing programs. The companies that include RSE programs for their workers consider it positive, because the work environment improved and the employees' productivity increased, which contributed for the welfare of both parties.

dc Arc Fault Effect on Hybrid ac/dc Microgrid

Science.gov (United States)

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.

Large cell lymphoma in children and adolescents of the Instituto Nacional de Cancerologia E.S.E. (Bogota, Colombia): 1980-2001

International Nuclear Information System (INIS)

De los Reyes I; Martinez, T; Vizcaino M; Moreno C

2005-01-01

Objective: to characterize and establish the survival of pediatric patients with lymphoma treated at the National Cancer Institute of Colombia, the period 1980-2001. Methods: clinical records of nineteen patients were reviewed, diagnosis was confirmed by morphology, and immune-phenotype was established with CD20, CD30, CD43, CD45RB, CD45RO, CD68, CD3, ALK, tdt and S-100 antibodies. Associations were established by using Fisher's exact test, Kaplan-Meier's method for survival, and the log rank test to compare survival trends. Results: ten patients were girls; the age median was eleven years, with a range between three and sixteen years. Seven cases presented lymphoma at the neck, which was the most frequent localization, nine patients were at stage l; the most frequent immune-phenotype was that of T cells, with eleven cases. Thirteen patients presented complete remission. After two years, event-free survival was 47.3%, disease-free survival was 99.8%, and global survival 68%. After five years, event-free survival was 28,8%. Conclusion: a bigger number of patients must be studied in order to establish more precise estimations concerning clinical features and survival

Milliwatt dc/dc Inverter

Science.gov (United States)

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.

75 FR 63040 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-30, DC...

Science.gov (United States)

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...

75 FR 68246 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

Science.gov (United States)

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...

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....

UREDINALES DE PLANTAS CULTIVADAS DE INTERÉS FLORAL EN COLOMBIA UREDINALES OF CULTIVATED FLOWERS IN COLOMBIA

Directory of Open Access Journals (Sweden)

Víctor Manuel Pardo Cardona

2006-06-01

Full Text Available Treinta especies de Uredinales (royas se han registrado en Colombia parasitando a veintiseis especies de plantas cultivadas de interés floral comprendidas en 21 géneros y 15 familias botánicas. Se registra para Colombia y la zona andina de Sudamérica a Puccinia hemerocallidis Thuemen. Se confirma la presencia en Colombia de Puccinia antirrhini Dietel & Holway y Uromyces gladioli P. Hennings.Thirty species of Uredinales (rust fungi are registered in Colombia parasitizing 26 species of cultivated flowers belonging to 21 genera and 15 botanical families. Puccinia hemerocallidis Thuemen is a new record for Colombia and the Andean zone of South America. Puccinia antirrhini Dietel & Holway and Uromyces gladioli P. Hennings are first records for Colombia.

A comparative analysis of costs of single and dual rapid HIV and syphilis diagnostics: results from a randomised controlled trial in Colombia.

Science.gov (United States)

Obure, Carol Dayo; Gaitan-Duarte, Hernando; Losada Saenz, Ricardo; Gonzalez, Lina; Angel-Muller, Edith; Laverty, Maura; Perez, Freddy

2017-11-01

HIV and congenital syphilis are major public health burdens contributing to substantial perinatal morbidity and mortality globally. Although studies have reported on the costs and cost-effectiveness of rapid diagnostic tests (RDTs) for syphilis screening within antenatal care in a number of resource-constrained settings, empirical evidence on country-specific cost and estimates of single RDTs compared with dual RDTs for HIV and syphilis are limited. A cluster randomised controlled study design was used to compare the incremental costs of two testing algorithms: (1) single RDTs for HIV and syphilis and (2) dual RDTs for HIV and syphilis, in 12 health facilities in Bogota and Cali, Colombia. The costs of single HIV and syphilis RDTs and dual HIV and syphilis RDTs were collected from each of the health facilities. The economic costs per woman tested for HIV and syphilis and costs per woman treated for syphilis defined as the total costs required to test and treat one woman for syphilis were estimated. A total of 2214 women were tested in the study facilities. Cost per pregnant woman tested and cost per woman treated for syphilis were US$10.26 and US$607.99, respectively in the single RDT arm. For the dual RDTs, the cost per pregnant woman tested for HIV and syphilis and cost per woman treated for syphilis were US$15.89 and US$1859.26, respectively. Overall costs per woman tested for HIV and syphilis and cost per woman treated for syphilis were lower in Cali compared with Bogota across both intervention arms. Staff costs accounted for the largest proportion of costs while treatment costs comprised <1% of the preventive programme. Findings show lower average costs for single RDTs compared with dual RDTs with costs sensitive to personnel costs and the scale of output at the health facilities. NCT02454816; results. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

DC to DC power converters and methods of controlling the same

Science.gov (United States)

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.

The Revolutionary Armed Forces of Colombia - People’s Army (FARC-EP): Marxist-Leninist Insurgency or Criminal Enterprise

Science.gov (United States)

2005-12-01

Landazábal’s public defiance of civil authority, the general was relieved of his position and subsequently retired. 32 Socorro Ramírez, “El proceso de...Bogotá D.C., 2003), 273. 33 Socorro Ramírez, “El proceso de paz de Belisario Betancur”, in Tiempos de Paz: Acuerdos en Colombia, 1902-1994, eds...José Miguel Narvaéz Martínez, Deputy Director of the Departamento Administrativo de Seguridad (Colombian equivalent of U.S. FBI), interview by author

Nuclear electronics

International Nuclear Information System (INIS)

Lucero B, E.

1989-01-01

The rapid technical development of Colombia over the past years, resulted among others, a considerable increase in the number of measuring instrumentation and testing laboratories, scientific research and metrology centers, in industry, agriculture, public health, education on the nuclear field, etc. IAN is a well organized institution with qualified management, trained staff and reasonably equipped laboratories to carry out tasks as: Metrology, standardization, quality control and maintenance and repair of nuclear instruments. The government of Colombia has adopted a policy to establish and operate through the country maintenance and repair facilities for nuclear instrumentation. This policy is reflected in the organization of electronic laboratories in Bogota-IAN

Hierarchical Velocity Control Based on Differential Flatness for a DC/DC Buck Converter-DC Motor System

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.

Rate Proposal for Remuneration of Air Pollutants Emissions From Stationary Sources Located in Bogota D.C.

Directory of Open Access Journals (Sweden)

Gabriel Herrera Torres

2011-04-01

Full Text Available The objective of this project is to develop a methodological proposal for the establishment of the retributive rate for the direct use of the atmosphere as the receptor of pollutant emissions that come from stationary resources on Bogotá D.C. By means of the emissions from stationary sources inventory and the air quality analysis, the pollutant that are emitted by the industries and the ones that are regulated by the network observations of the were identified selecting the particulated matter (PM10, sulfur oxides (SOx, and nitrogen oxides (NOx as the atmospheric pollutants that should be the object of payment in the retributive rate. Besides the selection of the pollutants that should be in the payment, the analysis of the retributive rate structure was made witch was based on the description or four key elements the generated fact, the tax base, the passive subject, and the fee of the rate. taking into account the social costs which are related to the investment being made by the district for the treatment of patients that present acute respiratory diseases ERA´s, associated and the costs of program control and monitoring of the air quality in Bogotá, the tariffs of the payment of the retributive rate were redefined in 281 $/Kg for the PM10, 2816 $/kg for the SOX and 2866 $/kg for NOX. Finally a new model of the payment was established, which is the result of the multiplication of the respective tariff for each of the pollutants that were selected as object of payment, expressed in ($/kg times, the charge of the pollutants emitted by the source expressed in (kg/ day.times the total number of days of the operation of the source emissions in a year.

Counterterrorism policy in Colombia

OpenAIRE

Self, Kevin A.

2007-01-01

The purpose of this thesis is to suggest a coherent, credible, and long-term counterterrorism policy in Colombia. The events of September 11, 2001 heightened U.S. awareness of Colombian terrorist organizations, the most powerful being the Revolutionary Armed Forces of Colombia (FARC). The U.S. counterterror approach in Colombia appears fragmented, with only minor changes to its previous drug control policies. In contrast, the Colombian government has developed and implemented a policy to ...

An Integrated Multifunctional Bidirectional AC/DC and DC/DC Converter for Electric Vehicles Applications

OpenAIRE

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...

Contamination of rice (Oryza sativa L) with Cadmium and Arsenic by irrigation with the Bogota River water in rice soils of the Lower Basin

International Nuclear Information System (INIS)

Montenegro, Omar; Mejia L

2001-01-01

In this study, field and greenhouse experiments were simultaneously carried out with rice (oryza sativa l., variedad oryzica-1) in soils of the Bogota River lower basin (Los Manueles Series, a member of the clayed, mixed, isohipertermic family of the Fluventic Vertic Haplustepts) to evaluate the effect of Cd and As content of the irrigation waters (of the Bogota River and greenhouse) on soils and: 1) rice growth physiological parameters; 2) Cd and As accumulated in different parts of rice plants; 3) yields and other aspects and properties of rice crop. The results lead to the following conclusions: 1) The Cd and As content of the Bogota River water, increased during the driest months and was minimum in those with the highest precipitation; Cd and As concentrations in both seasons surpassed the maximum permissible limits. 2) Rice height was highest when irrigation water does have neither Cd nor As. Effects of both elements showed an inverse lineal tendency. 3) The gradual increase of Cd in irrigation water reduced in 12.5% the number of grains per panicle; the increase of As induced a 10% reduction. 4) The highest concentration of Cd and As in irrigation waters significantly reduced yields; maximum yields l were obtained when Cd and As were absent from irrigation waters. 5) For any concentration of As in irrigation water the highest concentration of Cd was accumulated in rice leafs when concentration of Cd 2 was 2mg/l; above this value Cd accumulation in leafs el decreased with the gradual increase of As concentration. 6) Cd and As accumulated in rice grains increased with the gradual increment of both elements in the irrigation waters; Cd and As accumulated were respectively 50 and 15 times higher than the maximum critical levels proposed for rice grains. 7) Cd and As accumulated progressively on soils with gradual increase of both elements in irrigation waters 8) Cd and As concentration in irrigation waters apparently does not affect the rice mill behavior

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%.

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)

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.

DC/DC converters for integration of double-layer condensers in onboard power supply; DC/DC-Wandler zur Einbindung von Doppelschichtkondensatoren in das Fahrzeugenergiebordnetz

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.

Chaos analysis and chaotic EMI suppression of DC-DC converters

CERN Document Server

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

Full wave dc-to-dc converter using energy storage transformers

Science.gov (United States)

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.

The consequences of hospital autonomization in Colombia: a transaction cost economics analysis.

Science.gov (United States)

Castano, Ramon; Mills, Anne

2013-03-01

Granting autonomy to public hospitals in developing countries has been common over recent decades, and implies a shift from hierarchical to contract-based relationships with health authorities. Theory on transactions costs in contractual relationships suggests they stem from relationship-specific investments and contract incompleteness. Transaction cost economics argues that the parties involved in exchanges seek to reduce transaction costs. The objective of this research was to analyse the relationships observed between purchasers and the 22 public hospitals of the city of Bogota, Colombia, in order to understand the role of relationship-specific investments and contract incompleteness as sources of transaction costs, through a largely qualitative study. We found that contract-based relationships showed relevant transaction costs associated mainly with contract incompleteness, not with relationship-specific investments. Regarding relationships between insurers and local hospitals for primary care services, compulsory contracting regulations locked-in the parties to the contracts. For high-complexity services (e.g. inpatient care), no restrictions applied and relationships suggested transaction-cost minimizing behaviour. Contract incompleteness was found to be a source of transaction costs on its own. We conclude that transaction costs seemed to play a key role in contract-based relationships, and contract incompleteness by itself appeared to be a source of transaction costs. The same findings are likely in other contexts because of difficulties in defining, observing and verifying the contracted products and the underlying information asymmetries. The role of compulsory contracting might be context-specific, although it is likely to emerge in other settings due to the safety-net role of public hospitals.

Pulsewidth modulated DC-to-DC power conversion circuits, dynamics, and control designs

CERN Document Server

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

Cambios histomorfológicos en el ovario del pez capitán, Eremophilus mutisii Humboldt 1805 (Pisces: Trichomyteridae, durante el ciclo reproductivo anual,en la laguna del Muña, sistema río Bogotá, Colombia

Directory of Open Access Journals (Sweden)

Plutarco Cala Cala

1982-01-01

Full Text Available The principal aim of this investigation was to study the anual morpho-histological changes in the ovary of the fish capitan, Eremophilus mutisii, in the Rio Bogota basin in Colombia, with regard to the reproductive cycle, size of the mature fishes and seasonal changes in the environment. The fibs material was collected monthly. The gonads were fixed in Bouin's fixative. Subsequently they were washed several times in 70% ethanol. Transversal sections of about 5 cm in length, each of which produced 10 slides with 10 or so sections per slide, were taken from the center to the anterior portion of the right ovary of each fish, since no macroscopic significant differencie was observed in the oogenic process in the anterior, central and posterior portion of the ovary. The sections were dehydrated in tetrahydrofuran and embedded in paraffin. Sections were cut at 6 microns and stained with haematoxylin and eosin (H & E. The gonosomatic index (GSI or maturity index (MIl was calculated.

Triple voltage dc-to-dc converter and method

Science.gov (United States)

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.

Colombia: Issues for Congress

National Research Council Canada - National Science Library

Veillette, Connie

2005-01-01

... into sharper focus after the attacks of September 11, 2001. The United States has made a significant commitment of funds and material support to help Colombia and the Andean region fight drug trafficking since the development of Plan Colombia in 1999...

Switching coordination of distributed dc-dc converters for highly efficient photovoltaic power plants

Science.gov (United States)

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.

The performance of the DC motor by the PID controlling PWM DC-DC boost converter

OpenAIRE

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...

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...

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....

75 FR 27401 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-9-30, DC-9-40, and DC-9-50...

Science.gov (United States)

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...

A Feed-Forward Control Realizing Fast Response for Three-Branch Interleaved DC-DC Converter in DC Microgrid

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.

A Feed-Forward Control Realizing Fast Response for Three-Branch Interleaved DC-DC Converter in DC Microgrid

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....

Using PBL to Improve Educational Outcomes and Student Satisfaction in the Teaching of DC/DC and DC/AC Converters

Science.gov (United States)

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…

Churg-Strauss syndrome

International Nuclear Information System (INIS)

Ayala, Jose Javier; Velasquez, Juan Carlos

2005-01-01

Churg-Strauss Syndrome was described in 1951 and it is characterized by asthma, fever, hypereosinophilia and vasculitis. In 1990, following the discussion of several proposals for its classification, the American College of Rheumatology established its diagnostic criteria. A 55 year-old female patient was seen recently at the Military Hospital in Bogota, Colombia, with leucocytoclastic vasculitis, wheezing, pulmonary infiltrates and hypereosinophilia, who met all the criteria to be classified as a Churg-Strauss patient

Churg-Strauss syndrome; Sindrome de Churg Strauss

Energy Technology Data Exchange (ETDEWEB)

Ayala, Jose Javier; Velasquez, Juan Carlos

2005-07-01

Churg-Strauss Syndrome was described in 1951 and it is characterized by asthma, fever, hypereosinophilia and vasculitis. In 1990, following the discussion of several proposals for its classification, the American College of Rheumatology established its diagnostic criteria. A 55 year-old female patient was seen recently at the Military Hospital in Bogota, Colombia, with leucocytoclastic vasculitis, wheezing, pulmonary infiltrates and hypereosinophilia, who met all the criteria to be classified as a Churg-Strauss patient.

An XPS study of tarnishing of a gold mask from a pre-Columbian culture

International Nuclear Information System (INIS)

Bastidas, D.M.; Cano, E.; Gonzalez, A.G.; Fajardo, S.; Lleras-Perez, R.; Campo-Montero, E.; Belzunce-Varela, F.J.; Bastidas, J.M.

2008-01-01

The tarnishing originated on a hammered gold mask was analysed. Red tarnishing was observed after three years of storage in an indoor environment in the Gold Museum of Banco de la Republica, Bogota, Colombia. Silver sulphide (Ag 2 S) and silver sulphate (Ag 2 SO 4 ) compounds were identified as the origin of the tarnishing phenomenon, which is attributed to environmental contamination. Atomic absorption spectroscopy (AAS) and X-ray photoelectron spectroscopy (XPS) techniques were used

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...

LAS MIGRACIONES INTERNACIONALES EN COLOMBIA

Directory of Open Access Journals (Sweden)

Maguemati Wabgou

2012-01-01

Full Text Available El artículo expone los resultados de una investigación sobre los flujos migratorios internacionales que han estado llegando a Colombia desde el siglo XVI hasta la actualidad. La metodología investigativa se fundamenta en la recolección y el análisis de datos derivados de investigaciones anteriores. Los resultados son significativos en lamedida que presentan el estado de las migraciones en Colombia entre los siglos XVI y XIX y desde la primera mitad del siglo XX hasta la actualidad. Por un lado, engloban a la inmigración británica, jamaiquina y africana en las islas de San Andrés y Providencia; junto con la inmigración árabe, judía, alemana, francesa, italiana y gitana en Colombia continental. Por otro, aluden a las migraciones japonesas, suramericanas, junto con los crecientes asentamientos de migrantes norteamericanos, europeos y las nuevas oleadas de migraciones asiáticas y africanas en Colombia. Todo ello lleva a aprehender la envergadura del papel jugado por Colombia como un país de destino de las migraciones internacionales, lo que contrasta con la imagen más conocida de Colombia como un país expulsor de emigrantes.

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

Science.gov (United States)

Divan, Deepakraj M.

1990-01-01

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

An Integrated Multifunctional Bidirectional AC/DC and DC/DC Converter for Electric Vehicles Applications

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.

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...

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.

Quasi-Z-Source Half-Bridge DC-DC Converter for Photovoltaic Applications

OpenAIRE

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.

DC motor operation controlled from a DC/DC power converter in pulse mode with low duty cycle

OpenAIRE

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.

Arms Trafficking and Colombia

Science.gov (United States)

2003-01-01

chronology of the intensification of violence in the area, see Noche Y Niebla: Panorama De Derechos Humanos Y Violencia Politica En Colombia, Bogotá...Arms, London, UK: Zed Books, 2000, pp. 155–178. Noche Y Niebla: Panorama De Derechos Humanos Y Violencia Politica En Colombia, Bogotá: Cinep & Justicia

Observatorio de Política Internacional I. COLOMBIA - Una paz esquiva

OpenAIRE

Neira Fernández, Enrique

2007-01-01

Observatorio de Política Internacional I. COLOMBIA (Neira Fernández, Enrique) RECIENTES Año 2008 Colombia. Cerca el fin del paramilitarismo Colombia. Cerca el fin de las Farc Colombia. Conflicto armado y desarrollo humano Colombia. Política exterior Colombia. Inicia el 2008 con buen pie Año 2007 Colombia. Tras las pasadas elecciones Colombia. El espectro de las próximas elecciones Colombia. La garrocha de Uribe Colombia. III Parapolíticos Colombia. II...

Observatorio de Política Internacional I. COLOMBIA - Una paz secuestrada

OpenAIRE

Neira Fernández, Enrique

2007-01-01

Observatorio de Política Internacional I. COLOMBIA (Neira Fernández, Enrique) RECIENTES Año 2008 Colombia. Cerca el fin del paramilitarismo Colombia. Cerca el fin de las Farc Colombia. Conflicto armado y desarrollo humano Colombia. Política exterior Colombia. Inicia el 2008 con buen pie Año 2007 Colombia. Tras las pasadas elecciones Colombia. El espectro de las próximas elecciones Colombia. La garrocha de Uribe Colombia. III Parapolíticos Colombia. II...

Selección de una tecnología de banda ancha para la Universidad Nacional de Colombia — Sede Bogota, usando una técnica de decisión multicriterio

Directory of Open Access Journals (Sweden)

Félix Antonio Cortés Aldana

2007-01-01

Full Text Available La Universidad Nacional de Colombia Sede Bogotá (U.N. Bogotá ha planteado un proyecto para mejorar sus servicios de acceso a Internet mediante el empleo de una tecnología de banda ancha. En una fase inicial del proyecto se ha tenido que seleccionar la tecnología más adecuada entre las cuatro disponibles en Colombia: LMDS, ADSL, Cable Modem y Fibra óptica. Para adoptar esta decisión se ha aplicado el proceso analítico le- rárquico (AHP. Este método, basado en el análisis de decisiones multicriterio (MCDA, permite establecer los criterios de decisión, ponderarlos y valorar las alternativas en función de las prioridades que el decisor establezca para cada criterio. Como apoyo en todo el proceso de decisión se ha considerado la opinión de diferentes expertos. En la presente comunicación se expone el proceso seguido con el objetivo de mostrar que el empleo de métodos basados en el análisis de decisiones multicriterio (MCDA puede resultar útil a la hora de adoptar decisiones complejas.

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)

Novel composite resonance DC-DC converter with voltage doubler rectifier

OpenAIRE

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.

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...

Risk Monitoring through Traceability Information Model

OpenAIRE

Juan P. Zamora; Wilson Adarme; Laura Palacios

2012-01-01

This paper shows a traceability framework for supply risk monitoring, beginning with the identification, analysis, and evaluation of the supply chain risk and focusing on the supply operations of the Health Care Institutions with oncology services in Bogota, Colombia. It includes a brief presentation of the state of the art of the Supply Chain Risk Management and traceability systems in logistics operations, and it concludes with the methodology to integrate the SCRM model with the traceabili...

75 FR 61352 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-30, DC-10-30F, DC-10-30F (KC...

Science.gov (United States)

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...

Sliding-Mode Control of a Charger/Discharger DC/DC Converter for DC-Bus Regulation in Renewable Power Systems

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.

Design and Analysis of Two-Phase Boost DC-DC Converter

OpenAIRE

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...

SCM Handbooks for dc-to-dc Converters

Science.gov (United States)

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.

Isolated step-down DC -DC converter for electric vehicles

Science.gov (United States)

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.

Colombia en la guerra de Corea Colombia in Korea ’s war

Directory of Open Access Journals (Sweden)

Adolfo León Atehortúa Cruz

2008-06-01

Full Text Available Este artículo se ocupa de cinco aspectos poco explorados con respecto a la Guerra de Corea: la decisión de participar en el conflicto por parte del gobierno colombiano; la selección de los oficiales al frente del Batallón Colombia; la búsqueda de armas para el gobierno de Laureano Gómez; la experiencia obtenida por el Ejército de Colombia, y la influencia norteamericana profundizada con ella.This article refers five aspects scarcely explored on the Korea ’s War: the Colombian decision of participating in the conflict; the selection of the officials in the Battalion Colombia; the search for weapons by Laureano Gómez; the experience obtained by the Colombian Army, and the North American influence established on that period.

75 FR 75872 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-9-30, DC-9-40, and DC-9-50...

Science.gov (United States)

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...

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...

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.

Laboratory manual for pulse-width modulated DC-DC power converters

CERN Document Server

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

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...

The genus morpho in colombia: I. species present in colombia, and their geographic and altitudinal distribution El genero Morpho en Colombia: I. especies presentes en Colombia, distribución geográfica y altitudinal

Directory of Open Access Journals (Sweden)

Rodríguez Claudia

1994-06-01

Full Text Available This work puts together the results of six studies carried out in Colombia on the genus Morpho, with a revised description of. the species found in Colombia based on color patterns and mal e
genitalia. Biological and ecological data are included, such as geographic and altitudinal distribution, habitat, habits and behavior, and annotated comments on each of the 24 species.
The work features drawings of genitalia for each species, some of which had not been published before. This first issue covers the distribution of species found in Colombia.En este trabajo, se presentan los resultados de los estudios sobre el género Morphoen Colombia recopilados (6, con una redescripción de las especies del género que habitan en Colombia, con base en las características de patrones de
coloración y genitalias. Simultáneamente, se incluyen datos biológicos y ecológicos, como: distribución geográfica y altitudinal, hábitos, hábitat y comportamiento, además de otras anotaciones y comentarios de cada una de las 24 especies; se adicionan gráficos simplificados de las genitalias de cada una de las especies, muchas de las cuales no habían sido ilustradas anteriormente y, finalmente, se incluyen los registros de diferentes colecciones. En esta primera entrega, se señala la distribución geográfica y altitudinal de las especies que habitan en Colombia.

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.

CISH is induced during DC development and regulates DC-mediated CTL activation.

Science.gov (United States)

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.

La salud en Colombia. Marcela Vélez. Bogotá, D.C.: Penguin Random House Grupo Editorial; 2016

Directory of Open Access Journals (Sweden)

Omar Segura

2016-04-01

Full Text Available Colombia afronta una crisis en su sistema de seguridad social en salud prácticamente desde cuando fue promulgada la Ley 100 el 20 diciembre de 1993. Casi una generación después, Marcela Vélez quiere explicar en 207 páginas la crisis de un modelo de aseguramiento, prestación de servicios y salud pública que ha resultado inadecuado para el desarrollo social y económico del país. La autora también pretende mostrar cómo este conocimiento puede servir para argumentar su rechazo al sistema y proponer cambios, ya que nuevas componendas legales disfrazadas de reforma solo empeorarán las cosas.

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...

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...

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.

Influencia de las condiciones ambientales de la ciudad de Bogotá sobre el comportamiento mecánicos de una mezcla asfáltica Influence of the Bogotá environmental conditions on the mechanical behavior of an asphalt mixture

Directory of Open Access Journals (Sweden)

Hugo Alexander Rondón Quintana

2009-08-01

Full Text Available El artículo presenta el cambio que experimenta el módulo resiliente, la deformación permanente y la resistencia última bajo carga monotónica de una mezcla asfáltica densa en caliente cuando es expuesta al ambiente de la ciudad de Bogotá D.C. (Colombia. Las mezclas fueron elaboradas y evaluadas empleando dos cementos asfálticos (CA y un CA modificado (CAM con polímero tipo etil vinil acetato: CA 80-100, CA 60-70 y CAM 20-40 respectivamente. Con el fin de observar su evolución en el tiempo, a la fecha los parámetros mecánicos de las mezclas han sido medidos cada tres meses aproximadamente durante 20 meses para el caso de las mezclas fabricadas con los CA 80-100 y CA 60-70, y 10 meses para aquellas que emplearon el CAM 20-40. De los resultados se concluye que el comportamiento que experimentan las mezclas depende del tipo de CA utilizado. Adicionalmente, la tendencia de las mezclas con los tres tipos de CA es experimentar un aumento en los valores de rigidez con el tiempo de exposición al ambiente debido principalmente a procesos de endurecimiento por envejecimiento de los ligantes asfálticos.The paper presents the evolution of the resilient modulus, permanent deformation and strength under monotonic loading of a dense hot mixture due to long term exposure to the environment in the city of Bogota D.C. (Colombia. The mixtures were made using two asphalt cements (AC and modified asphalt cement (MAC with ethil-vinil-acetate: AC 80-100, AC 60-70 and MAC 20-40 respectively. The mechanical properties have been evaluated every three months over a period of 20 months for the AC 80-100 and AC 60-70, and 10 months for MAC 20-40. The results show differences depending on the type of cement. All mixtures increase the modulus with time due to aging of the asphalt cement.

Determination of input/output characteristics of full-bridge AC/DC/DC converter for arc welding

OpenAIRE

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.

ITAR Free Commercial-of-the-Shelf DC/DC Converter

Science.gov (United States)

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.

Thinking and questioning the social construction of space: balances and challenges

OpenAIRE

Nubia Moreno Lache; Alexander Cely Rodríguez; Liliana Rodríguez Pizzinato

2013-01-01

DOI: http://dx.doi.org/10.17227/01234870.38folios141.156 This paper offers an overview and reflections of the research done within the emphasis on “Social Construction of Space”, of the master’s program in Social Sciences at the National Pedagogical University in Bogota, Colombia. The goal is to examine two issues: the relationships that community establishes with the biophysical and social environment and also the cultural, economical and political impact on geographic places, such as th...

Congenital unilateral absence of the pulmonary artery in adults

International Nuclear Information System (INIS)

Gonzalez Garcia, Mauricio; Escalante Mora, Hector A; Lozano Castillo, Alfonso J

2000-01-01

Unilateral absence of a pulmonary artery is a rare anomaly. It occurs with pulmonary ipsilateral hypoplasia and it's frequently associated with other cardiovascular malformations. The majority of the cases are diagnosed in childhood. This is a case report of two adult patients of the Hospital Central de la Policia Nacional in Bogota, Colombia, with unilateral absence of the pulmonary artery one isolated and the other with patent ductus arteriosus. We describe the clinical and roentgenographic findings of this congenital anomaly

Performance of 22.4-kW nonlaminated-frame dc series motor with chopper controller. [a dc to dc voltage converter

Science.gov (United States)

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.

Hydrocarbon export and production in Colombia. Present time and perspectives; Exportacion y produccion de hidrocarburos en Colombia: Actualidad y perspectiva

Energy Technology Data Exchange (ETDEWEB)

Herbert, Richard [BP Exploration (Colombia)

1997-07-01

The present projects of operation of new fields will increase the importance of Colombia as exporter of crude. This paper analyzes the process of operation and oil production in Colombia under three subjects: the transition process in this country, future challenges and the necessary associations between the private sector and the state for the success. A projection is made of the oil production in Colombia from 1980 to 2010, as well as of the reserves and production of gas. [Spanish] Los proyectos actuales de explotacion de nuevos campos aumentaran la importancia de Colombia como exportador de crudo. Este trabajo analiza el proceso de explotacion y produccion de petroleo en Colombia bajo tres temas: el proceso de transicion en este pais, sus retos futuros y las asociaciones entre el sector privado y el estado necesarias para el exito. Se hace una proyeccion de la produccion petrolera en Colombia de 1980 al 2010 asi como de las reservas y produccion de gas.

Shadow Toll in Colombia

OpenAIRE

González Ruiz, Juan David; Botero Botero, Sergio; Arboleda, Carlos Alejandro; Duque Grisales, Eduardo Alexander

2015-01-01

The growing development in infrastructure projects in Colombia has been linked to legal adjustments and capital markets. These two last factors have provided important elements for project developers to design funding strategies. Based on the shadow toll scheme, this paper proposes a new financing strategy for funding highway projects. This strategy may be implemented in Colombia. Finally, the paper proposes future research on shadow toll schemes as a financial mechanism.

Characterising and modelling extended conducted electromagnetic interference in densely packed DC-DC converter

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...

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.

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...

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...

Académico Doctor Julio Hernando Ordoñez Garay (1910-2008.

Directory of Open Access Journals (Sweden)

Jaime Gómez-González

2008-03-01

Condecorado con el “Premio a una Vida” por la Sociedad de Cardiología, en calidad de Precursor de la Cardiología en Colombia. Miembro del Comité de redacción del Acta Physiologica Latinoamericana, Buenos Aires (1971, Miembro del Consejo Asesor del Fondo Colombiano de Investigaciones Científicas (Colciencias (1970, Medalla de la Facultad de Medicina de la Universidad Javeriana, Comendador, Medico, Fundador y Profesor. Premio Alejandro Angel Escobar, Mención Honorífica (1957. Organizador y primer presidente del Congreso Colombiano de Cardiología, (Bogota 1956. Profesor visitante de la Unesco al Simposio sobre Biología de la Altura (Lima 1949, Fundador y Director de los Anales de Biología (Bogota, Miembro del Comité de Redacción de la Revista British Abstracts (Londres. Citado por Jalbosky S, en el libro Ilustrated Dictionary of Eponyms, por una nueva entidad nosológica que denomina “Ordoñez Melanosis” (Saunders Co, 1969;229.

Uribe, M. (2013. La Nación Vetada. Estado, desarrollo y guerra civil en Colombia. Bogotá, D.C: Universidad Externado de Colombia, 343 pp.

Directory of Open Access Journals (Sweden)

Juan Carlos Villamizar

2017-01-01

Full Text Available El libro plantea una tesis sugestiva que será objeto de discusión en la futura historiografía acerca del proceso político colombiano en la segunda mitad del siglo XX: la explicación de las causas de la persistencia de la guerra civil en Colombia por cerca de sesenta años. Uribe explica cómo la sociedad colombiana ha mantenido una guerra civil prolongada desde 1964, la cual se ha configurado por la coexistencia del veto de las élites a la Nación, un estilo de desarrollo concentrador de la riqueza con sesgo anti-campesino y una adopción irrestricta de las élites a la política norteamericana. Los anteriores elementos se retroalimentan mutuamente generando una ruta, en la cual, la guerra civil es la marca distintiva.

A DC-DC Conversion Powering Scheme for the CMS Phase-1 Pixel Upgrade

CERN Document Server

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...

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.

Regulation of DC development and DC-mediated T-cell immunity via CISH

OpenAIRE

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.

Regulation of DC development and DC-mediated T-cell immunity via CISH.

Science.gov (United States)

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.

Observatorio de Política Internacional I. COLOMBIA - Una nueva estrategia de paz

OpenAIRE

Neira Fernández, Enrique

2007-01-01

Observatorio de Política Internacional I. COLOMBIA (Neira Fernández, Enrique) RECIENTES Año 2008 Colombia. Cerca el fin del paramilitarismo Colombia. Cerca el fin de las Farc Colombia. Conflicto armado y desarrollo humano Colombia. Política exterior Colombia. Inicia el 2008 con buen pie Año 2007 Colombia. Tras las pasadas elecciones Colombia. El espectro de las próximas elecciones Colombia. La garrocha de Uribe Colombia. III Parapolíticos Colombia. II...

Observatorio de Política Internacional I. COLOMBIA - Los momentos de la paz

OpenAIRE

Neira Fernández, Enrique

2012-01-01

Observatorio de Política Internacional I. COLOMBIA (Neira Fernández, Enrique) RECIENTES Año 2008 Colombia. Cerca el fin del paramilitarismo Colombia. Cerca el fin de las Farc Colombia. Conflicto armado y desarrollo humano Colombia. Política exterior Colombia. Inicia el 2008 con buen pie Año 2007 Colombia. Tras las pasadas elecciones Colombia. El espectro de las próximas elecciones Colombia. La garrocha de Uribe Colombia. III Parapolíticos Colombia. II...

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.

Elaboration of a velocity model of the Bogota basin (Colombia) based on microtremors arrays measurements, gravity data, and geological information

Science.gov (United States)

Pulido Hernandez, N. E.; Senna, S.; Garcia, H. Mr; Montejo, S.; Reyes, J. C.

2017-12-01

Bogotá, a megacity with almost 8 million inhabitants is prone to a significant earthquake hazard due to nearby active faults as well as subduction megathrust earthquakes. The city has been severely affected by many historical earthquakes in the last 500 years, reaching MM intensities of 8 or more in Bogotá. The city is also located at a large lacustrine basin composed of extremely soft soils which may strongly amplify the ground shaking from earthquakes. The basin extends approximately 40 km from North to South, is bounded by the Andes range to the East and South, and sharply deepens towards the West of Bogotá. The city has been the subject of multiple microzonations studies which have contributed to gain a good knowledge on the geotechnical zonation of the city and tectonic setting of the region. To improve our knowledge on the seismic risk of the city as one of the topics, we started a 5 years project sponsored by SATREPS (a joint program of JICA and JST), entitled "Application of state of the art technologies to strengthen research and response to seismic, volcanic and tsunami events and enhance risk management in Colombia (2015-2019)". In this paper we will show our results for the elaboration of a velocity model of the city. To construct a velocity model of the basin we conducted multi-sized microtremors arrays measurements (radius from 60 cm up to 1000 m) at 41 sites within the city. We calculated dispersion curves and inferred velocity profiles at all the sites. We combine these results with gravity measurements as well as geological information to obtain the initial velocity model of the basin. Ackowledgments This research is funded by SATREPS (a joint program of JICA and JST).

Los hongos de Colombia - IV. Bisporella Triseptata and its allies in Colombia Los hongos de Colombia - IV. Bisporella Triseptata and its allies in Colombia

Directory of Open Access Journals (Sweden)

Carpenter S. E.

1978-12-01

Full Text Available During the combined mycological explorations of Colombia by the Instituto de Ciencias Naturales (Bogotá, Instituto Colombiano Agropecuario (Bogotá and The New York Botanical Garden, many new and interesting fungi have been discovered. Among these, several collections of an apparently rare and poorly known species of Bisporella Sacc. were made, which are worthy of report.During the combined mycological explorations of Colombia by the Instituto de Ciencias Naturales (Bogotá, Instituto Colombiano Agropecuario (Bogotá and The New York Botanical Garden, many new and interesting fungi have been discovered. Among these, several collections of an apparently rare and poorly known species of Bisporella Sacc. were made, which are worthy of report.

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.

Analysis of high voltage step-up nonisolated DC-DC boost converters

Science.gov (United States)

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.

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...

Analysis and Design of Bi-Directional DC-DC Converter in the Extended Run Time DC UPS System Based on Fuel Cell and Supercapacitor

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...

Assessing the deep drilling potential of Lago de Tota, Colombia, with a seismic survey

Science.gov (United States)

Bird, B. W.; Wattrus, N. J.; Fonseca, H.; Velasco, F.; Escobar, J.

2015-12-01

Reconciling orbital-scale patterns of inter-hemispheric South American climate during the Quaternary requires continuous, high-resolution paleoclimate records that span multiple glacial cycles from both hemispheres. Southern Andean Quaternary climates are represented by multi-proxy results from Lake Titicaca (Peru-Bolivia) spanning the last 400 ka and by pending results from the Lago Junin Drilling Project (Peru). Although Northern Andean sediment records spanning the last few million years have been retrieved from the Bogota and Fúquene Basins in the Eastern Cordillera of the Colombian Andes, climatic reconstructions based on these cores have thus far been limited to pollen-based investigations. When viewed together with the Southern Hemisphere results, these records suggest an anti-phased hemispheric climatic response during glacial cycles. In order to better assess orbital-scale climate responses, however, independent temperature and hydroclimate proxies from the Northern Hemisphere are needed in addition to vegetation histories. As part of this objective, an effort is underway to develop a paleoclimate record from Lago de Tota (3030 m asl), the largest lake in Colombia and the third largest lake in the Andes. One of 17 highland tectonic basins in Eastern Cordillera, Lago de Tota formed during Tertiary uplift that deformed pre-foreland megasequences, synrift and back-arc megasequences. The precise age and thickness of sediments in the Lago de Tota basin has not previously been established. Here, we present results from a recent single-channel seismic reflection survey collected with a small (5 cubic inch) air gun and high-resolution CHIRP sub-bottom data. With these data, we examine the depositional history and sequence stratigraphy of Lago de Tota and assess its potential as a deep drilling target.

DC-DC power converter research for Orbiter/Station power exchange

Science.gov (United States)

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.

The dual burden of malnutrition in Colombia.

Science.gov (United States)

Sarmiento, Olga L; Parra, Diana C; González, Silvia A; González-Casanova, Inés; Forero, Ana Y; Garcia, Johnattan

2014-12-01

Almost all nutrition policies in Colombia currently focus on either undernutrition or obesity, with the predominant emphasis on undernutrition. It is crucial to assess the prevalence of the dual burden of malnutrition in Colombia to better target programs and policies. The aim was to estimate the national prevalence of the dual burden of malnutrition in Colombia at the individual and household levels in children aged malnutrition was defined as the coexistence of overweight and stunting or anemia in the same person or household. In Colombia, low to high prevalences of overweight and obesity (3.4-51.2%) coexist with moderate to high prevalences of anemia (8.1-27.5%) and stunting (13.2%). The observed prevalence of the dual burden was lower than expected. Approximately 5% of households had at least one stunted child aged malnutrition in Colombia are lower than expected. Despite the independence of the occurrence of these conditions, the fact that the dual burden coexists at the national, household, and intraindividual levels suggests that public policies should address both conditions through multiple strategies. It is imperative to evaluate the current nutrition policies to inform malnutrition prevention efforts in Colombia and to share lessons with other countries at a similar stage of nutritional transition. © 2014 American Society for Nutrition.

A pollen diagram from “Laguna de la Herrera” (Sabana de Bogota)

NARCIS (Netherlands)

Hammen, van der T.; Gonzalez, E.

1965-01-01

The Laguna de La Herrera (alt. ca 2550 m) is a lake situated on the western border of the Sabana de Bogotá, near Mosquera (dept. of Cundinamarca, Colombia) (fig. 2). This part of the Sabana has a relatively dry climate (appr. 600—700 mm rainfall), as it lies in the rain-shadow of the hills that

Evaluation of the contamination for Hg and Pb in horticultural soils of the Bogota Savanna and of the effect of the Hg and Pb of the watering water and of the soils in several vegetables

International Nuclear Information System (INIS)

Vargas Zarate, Orlando; Mejia C, Leonidas

1998-01-01

Soils of six different horticultural zones of the Sabanna of Bogota were studied to quantify Hg and Pb accumulation in soils and crops caused by traditional and continuous irrigation with the highly polluted waters of Bogota River and its effluents. Soils of site No.6 representative of Rio Bogota is series (a fine clayed, mixed, isothermic family of aeric fluventic tropaquepts) was selected for greenhouse experiments conducted to show: a) The amounts of Hg and Pb absorbed by 3 different vegetables (lettuce, cucumber and carrots) grown under greenhouse conditions, irrigated with waters with variable Hg and Pb concentrations; b) the effects of increased levels of Hg and Pb in irrigation water on the accumulation level of both metals in soils at the harvest; and c) the individual effect and interactions of Hg and Pb on yields of each one vegetable. Results afforded this conclusions: 1) soils of all six sites have average Hg and Pb concentrations (0.5 and 110 ppm respectively) which exceed normal levels for soils (who, 1976); site 6 has the highest level of Hg and Pb accumulation (1.6 and 3.36 ppm); 2) for all three vegetables Hg and Pb accumulation level was almost proportional to Hg and Pb concentration in irrigation water; 3) Hg and Pb concentration in edible parts was different for each vegetable. Average contents of Hg and Pb were respectively 33 ppb and 172 ppm in lettuce; 24 ppb and 10 ppm in cucumber and 36 ppb and 48 ppm in carrots. Average absorption of Pb in lettuce was 17 times higher than in cucumber and 3.5 times higher than in carrots; Pb absorption levels widely surpass those recommended as permissible by WHO (1976) 4) high correlation coefficients were found between Hg and Pb absorption by lettuce (R=0.94 and 0.97 respectively), cucumber (R=0.89 and R=0.80 respectively) and carrots (R=0.99 y R=0.85 respectively) and the corresponding Hg and Pb accumulation levels in soils at harvest; 5) Effects of Hg and Pb levels in irrigation water on yields was

Violence and health in Colombia Violencia y salud en Colombia

Directory of Open Access Journals (Sweden)

Saúl Franco Agudelo

1997-09-01

Full Text Available In Colombia, violence seems uncontrollable. Along with massacres and group killings of astonishing cruelty, there are also kidnappings and disappearances, abuse of children and the elderly, and rape of young adolescents. Every day, without respite, Colombians are witnesses or victims of street crimes as well as racial, sexual, and socioeconomic discrimination. Unwillingly, they become agents of aggression in public transport, at home, at school, and at work. Colombia has the highest rates of mortality from homicide in the world. Apart from the enormous institutional burden that violence imposes on the health services and forensic medicine, it now constitutes the principal public health problem in the country. To confront it, the health sector must develop policies and finance actions, develop innovative ways to train personnel, implement public education processes, and devote more effort and greater creativity to research, which up to now has provided some important, albeit insufficient, responses. Violence, which is the substitution of force for any type of dialogue, must be considered within the context of life and health. Doing so is not an attempt to rationalize violence, much less to substitute words or reflection for action, but rather an attempt to understand it in depth in order to search for alternatives. With that goal, this article analyzes the subject of violence in Colombia, principally from the perspective of its effect on the health of the citizens and its implications for the health sector. The author fully recognizes the subjectivity and limitations of the views he expresses herein.La violencia en Colombia parece incontenible. A las masacres y asesinatos colectivos, de una crueldad desconcertante, se suman los secuestros y desapariciones, el maltrato de niños y ancianos y las violaciones de adolescentes. Cada día, sin tregua, los colombianos son espectadores o víctimas de atracos callejeros y de discriminación racial, sexual

Violencia y salud en Colombia Violence and health in Colombia

Directory of Open Access Journals (Sweden)

Saúl Franco Agudelo

1997-02-01

Full Text Available La violencia en Colombia parece incontenible. A las masacres y asesinatos colectivos, de una crueldad desconcertante, se suman los secuestros y desapariciones, el maltrato de niños y ancianos y las violaciones de adolescentes. Cada día, sin tregua, los colombianos son espectadores o víctimas de atracos callejeros y de discriminación racial, sexual y socioeconómica. Sin quererlo, se convierten en agentes de agresiones en el transporte urbano, el hogar, la escuela y el trabajo. Colombia tiene las tasas de mortalidad por homicidio más altas del mundo. Independientemente de la enorme sobrecarga institucional que impone a los servicios de salud y medicina legal, la violencia constituye actualmente en Colombia el principal problema de salud pública. Para hacerle frente, el sector de la salud debe elaborar políticas y financiar acciones; crear nuevos procesos de formación de personal, poner en marcha procesos de educación pública, y dedicar mayor esfuerzo y creatividad al campo de la investigación, que hasta ahora ha dado respuestas importantes pero aún insuficientes. Al reflexionar sobre la violencia, que es la sustitución de toda argumentación por la fuerza, es necesario ubicarla en el contexto de la vida y la salud. No se pretende solo racionalizarla, y menos aún sustituir la acción por la palabra o por las reflexiones, sino tratar de comprenderla a fondo con el objeto de buscarle alternativas. En el presente artículo se analiza, con esta finalidad, el tema de la violencia en Colombia, principalmente desde el punto de vista de su efecto en la salud de los colombianos y de sus implicaciones para el sector sanitario. El autor expone sus puntos de vista con plena conciencia de su subjetividad y limitaciones.In Colombia, violence seems uncontrollable. Along with massacres and group killings of astonishing cruelty, there are also kidnappings and disappearances, abuse of children and the elderly, and rape of young adolescents. Every day

Preservation by Irradiation of three varieties of Colombian Potatoes (Solanum Tuberosum L.)

International Nuclear Information System (INIS)

Zuleta, S.

1986-01-01

This is first study performed in the Gamma Facility of the Instituto de Asuntos Nucleares, in Bogota, Colombia, related to the Food Irradiation Programme. The study was made with: Parda Pastusa, ICA Guantiva, and ICA Purace, selected as the most important varieties of colombian potatoes. A complete study prior to the irradiation exposure was made in order to determine the optimum irradiation package. Different dose treatments, chemical and physical changes and organoleptic tests, were studied in this work. The work was performed in the early 1980s

Sliding-mode control of single input multiple output DC-DC converter

Science.gov (United States)

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.

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...

El Patentamiento Universitario en Colombia

Directory of Open Access Journals (Sweden)

Diana Milena González Gélvez

2013-04-01

Full Text Available El artículo presenta un panorama general del patentamiento que realizan las Universidades en Colombia. Para ello, se realiza un análisis de la información de la base de datos de patentes de la Superintendencia de Industria y Comercio de Colombia desde 1970 hasta 2010. Los resultados permiten observar el estado real del patentamiento Universitario en Colombia, así como identificar las Universidades más exitosas en el proceso de patentamiento y los tiempos reales requeridos para proteger las nuevas creaciones. Así mismo, los resultados son un insumo importante en la determinación de la estrategia de protección que adopten las Universidades Colombianas en cuanto a la protección de sus creaciones.

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.

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.

Colombia en la guerra de Corea Colombia in Korea ’s war

OpenAIRE

Adolfo León Atehortúa Cruz

2008-01-01

Este artículo se ocupa de cinco aspectos poco explorados con respecto a la Guerra de Corea: la decisión de participar en el conflicto por parte del gobierno colombiano; la selección de los oficiales al frente del Batallón Colombia; la búsqueda de armas para el gobierno de Laureano Gómez; la experiencia obtenida por el Ejército de Colombia, y la influencia norteamericana profundizada con ella.This article refers five aspects scarcely explored on the Korea ’s War: the Colombian decision of part...

Development of a DC-DC conversion powering scheme for the CMS Phase-1 pixel upgrade

CERN Document Server

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.

Auxiliary resonant DC tank converter

Science.gov (United States)

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.

Dc-To-Dc Converter Uses Reverse Conduction Of MOSFET's

Science.gov (United States)

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.

Colombia - The Quality of Education in Colombia : An Analysis and Options for a Policy Agenda

OpenAIRE

World Bank

2008-01-01

The main objective of this report is to analyze student learning in Colombia in order to foster policies to improve education quality that are grounded in research and the Colombian context. In 2006, Colombia participated for the first time in the Programme for International Student Assessment (PISA) of the Organization for Economic Cooperation and Development (OECD), which provides an imp...

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)

Strategi Counterinsurgency Kolombia terhadap Farc (Fuerzas Armadas Revolucionarias De Colombia) 2010-2012

OpenAIRE

Olivia, Yessi; Miranda, Dea

2014-01-01

This paper is analysing about counterinsurgency Colombia to against paramilitary group in Colombia to help address the humanitarian crisis that occurred because of civil conflict in Colombia. Conflict in Colombia involving the Fuerzas Armadas Revolucionaries de Colombia (FARC) and the Government of Colombia is one example of a threat to human security in this case is a citizen of Colombia. Thousands of people confirmed dead, and hundreds more injured and displaced into the surrounding area. C...

Prevalence of urticaria in Cartagena, Colombia

Directory of Open Access Journals (Sweden)

Pablo Andrés Miranda-Machado

2017-06-01

Full Text Available Background: In Colombia, there have been studies on the prevalence of allergic diseases such as asthma, allergic rhinitis and atopic dermatitis. Prevalence studies of urticaria in Colombia are scarce. Objective: Our objective of this study was to estimate the prevalence of urticaria in Cartagena (Colombia in order to contribute to national epidemiological estimates of disease. Methods: A multicenter cross-sectional study in the city of Cartagena was conducted and 547 patients aged 1-58 years treated at the Allergy specialist consultation in care centers selected for this study between April and July 2015 were included, through non-probabilistic sampling. Results: The prevalence of urticaria in the care centers selected of city of Cartagena (Colombia was 7.1 % (4 % children and adults 3.1 %. 3.4 % prevalence of acute urticaria and 3.6 % of chronic urticaria was estimated. Conclusion: 46.1 % reported having a poor quality of life associated with urticaria.

Observatorio de Política Internacional I. COLOMBIA - Siempre es tarde para la paz

OpenAIRE

Neira Fernández, Enrique

2007-01-01

Observatorio de Política Internacional I. COLOMBIA (Neira Fernández, Enrique) RECIENTES Año 2008 Colombia. Cerca el fin del paramilitarismo Colombia. Cerca el fin de las Farc Colombia. Conflicto armado y desarrollo humano Colombia. Política exterior Colombia. Inicia el 2008 con buen pie Año 2007 Colombia. Tras las pasadas elecciones Colombia. El espectro de las próximas elecciones Colombia. La garrocha de Uribe Colombia. III Parapolíticos Colombia. II...

Observatorio de Política Internacional I. COLOMBIA - Viraje en el proceso de paz

OpenAIRE

Neira Fernández, Enrique

2007-01-01

Observatorio de Política Internacional I. COLOMBIA (Neira Fernández, Enrique) RECIENTES Año 2008 Colombia. Cerca el fin del paramilitarismo Colombia. Cerca el fin de las Farc Colombia. Conflicto armado y desarrollo humano Colombia. Política exterior Colombia. Inicia el 2008 con buen pie Año 2007 Colombia. Tras las pasadas elecciones Colombia. El espectro de las próximas elecciones Colombia. La garrocha de Uribe Colombia. III Parapolíticos Colombia. II...

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....

DESIGN OPTIMIZATION OF RESONANT DC-DC CONVERTERS

OpenAIRE

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...

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.

Plan Colombia

Directory of Open Access Journals (Sweden)

Noam Chomsky

2000-12-01

Full Text Available Colombia recibe más ayuda militar de Estados Unidos que el resto de América Latina y el Caribe unidos, y esta situación puede profundizarse con la ejecución del Plan Colombia, fundamentado en la lucha antidrogas. Sin embargo, el pais ha sido calificado con el récord en violación de derechos humanos. En este contexto se aplica la reforma económica más significativa en la década de los noventa, generando condicionantes en los procesos de integración con sus vecinos. En concordancia con el secretario de Defensa, Henry Stimson, desde los años 60 Estados Unidos estaba autorizado para controlar su propio sistema regional, mientras todos los demás intenlos serian desmantelados. La presentación ambigua de esta política del gobierno estadounidense en Colombia es cómo disociar esta guerra contra la droga y la lucha irregular contrainsurgente En Estados Unidos hay otra opinión que debe conocerse para comprender las divergencias en e! interior de dicho país. Este artículo del prestigioso profesor universitario del MU, Noam Chomsky, es un referente obligado en términos de opinión pública y académica de dimensión internacional, por el inmenso respeto que infunde tanto en América como en Europa

CANCER DE MAMA EN COLOMBIA

Directory of Open Access Journals (Sweden)

Mario A. González Mariño

2014-12-01

Full Text Available OBJETIVO: Conocer la situación del cáncer de mama en Colombia mediante la revisión de publicaciones epidemiológicas y clínicas. MATERIALES Y MÉTODOS: Evaluación de estudios publicados en revistas científicas seriadas sobre cáncer de mama en Colombia mediante búsqueda en las bases de datos Medline con los términos neoplasm and breast and Colombia y Lilacs con neoplasia y mama y Colombia. Se seleccionaron los estudios con aplicación epidemiológica o clínica con muestreo o datos de mujeres residentes en Colombia, ubicando sus resultados en la sección de introducción y en la de discusión de acuerdo con los enfoques de promoción, prevención y tratamiento. RESULTADOS: Se encontraron 62 referencias en Medline de las que se seleccionaron 23 y en Lilacs de 16 se escogieron 4. Las referencias se descartaron en Medline por las siguientes razones: 15 por el diseño de estudio (revisión de tema, presentación de casos clínicos, 7 por tratarse de investigación básica, 10 por tema diferente al cáncer de mama en Colombia y 7 por datos pertenecientes a otro país. En Lilacs se excluyeron por: 7 artículos también presentes en Medline, 3 por diseño, 1 de investigación básica y 1 de un tema diferente. CONCLUSIONES: Los artículos revisados permiten tener una visión integral sobre el cáncer de mama en Colombia. En ellos se puede verificar que hay limitaciones en la prestación del servicio de atención en salud para esta enfermedad, y se identifican factores de riesgo con significancia estadística como la nuliparidad, niveles altos de inactividad física y exposición a DDE (diclorodifenildicloroeteno y para el cáncer genético se encontraron mutaciones fundadoras. La consulta se hace principalmente por síntomas, no sobre resultados de cribado como sería lo deseable. Existen también contribuciones sobre el manejo quirúrgico y adyuvante extrapolables a las condiciones del país.

On the modelling of linear-assisted DC-DC voltage regulators for photovoltaic solar energy systems

Science.gov (United States)

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.

Land Reform and Conflict Resolution in Colombia

National Research Council Canada - National Science Library

Nieswiadomy, Mark

2003-01-01

One of the leading arguments explaining the current rural conflict in Colombia is that it stems from deeply rooted peasant grievances over lack of land, As is true in much of Latin America, Colombia...

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.

Test Results of Selected Commercial DC/DC Converters under Cryogenic Temperatures - A Digest

Science.gov (United States)

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.

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....

United States Strategy in Colombia: New Opportunities

National Research Council Canada - National Science Library

Roberts, Lee C

2003-01-01

.... Despite decades of U.S. support to the Government of Colombia, the troika of guerrilla insurgency, civil disorder by paramilitaries, and illegal drug activities has brought Colombia close to becoming a failed State. U.S...

Muertes por causas violentas y ciclo económico en Bogotá, Colombia: un estudio de series de tiempo, 1997-2006 Death from violent causes and economic cycles in Bogota, Colombia: a time-series study, 1997-2006

Directory of Open Access Journals (Sweden)

José Moreno Montoya

2009-07-01

Full Text Available OBJETIVOS: Caracterizar las tendencias temporales del número de muertes por causas violentas en la ciudad de Bogotá entre 1997 y 2006 y analizar su posible asociación con los ciclos económicos de la ciudad. MÉTODOS: Estudio ecológico a partir de las cifras absolutas de muertes violentas registradas entre enero de 1997 y septiembre de 2006 en Santa Fe de Bogotá, Colombia. Se utilizaron modelos ARIMA de series de tiempo trimestrales para caracterizar el comportamiento de las muertes violentas. Como variables explicativas del ciclo económico de la ciudad se utilizaron las series trimestrales del índice de precios al consumidor, la tasa de desempleo y el número total de personas ocupadas; se evaluó su asociación con las series de muertes mediante modelos de función de transferencia. RESULTADOS: Del total de 36575 muertes por causas violentas en Bogotá, 57,7% fueron por homicidios y 23,7% por accidentes de tránsito. Las series de homicidios, suicidios y muertes por accidentes de tránsito mostraron tendencias decrecientes, con un marcado comportamiento estacional en las series de muertes por accidentes de tránsito y suicidios, con picos en los dos últimos trimestres de cada año. Se hallaron asociaciones significativas entre todas las series de muertes por las diferentes causas con al menos una serie económica y en cada caso se identificó el modelo de función de transferencia respectivo. CONCLUSIONES: Los homicidios constituyen la mayor parte de las muertes por causas violentas y revelan la existencia de patrones temporales en este tipo de muertes. Se encontraron asociaciones significativas entre las muertes por causas violentas y algunas variables económicas que describen el ciclo de la actividad en la ciudad. Se confirmó que diferentes circunstancias socioeconómicas que afectan a una sociedad pueden influir en el nivel de violencia.OBJECTIVES: To determine seasonal trends in the number of deaths from violence in Bogot

77 FR 59064 - United States-Colombia Trade Promotion Agreement

Science.gov (United States)

2012-09-26

...-Colombia Trade Promotion Agreement AGENCY: U.S. Customs and Border Protection, Department of Homeland... Trade Promotion Agreement entered into by the United States and the Republic of Colombia. DATES: Interim...-Colombia Trade Promotion Agreement (``CTPA'' or ``Agreement''), and on June 28, 2007, the Parties signed a...

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...

Multilevel DC link inverter

Science.gov (United States)

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.

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.

Studi Komparasi Fungsi Keanggotaan Fuzzy sebagai Kontroler Bidirectional DC-DC Converter pada Sistem Penyimpan Energi

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.

Environmental occurrence of arsenic in Colombia: A review

International Nuclear Information System (INIS)

Alonso, David L.; Latorre, Sergio; Castillo, Elianna; Brandão, Pedro F.B.

2014-01-01

The international literature on the presence of arsenic (As) in Latin America does not disclose the true magnitude of the presence of As in Colombia. In this paper, we summarize the literature on As occurrence in Colombia. The data reveal that As is present in matrices such as soil, sediments and water and in the food chain. Some of the As concentrations exceed the limits specified by national and international regulations. Arsenic higher concentrations are associated with mining regions (e.g., soils, up to 148 mg/kg; sediments, up to 1400 mg/kg) and agricultural areas (e.g., vegetables, up to 5.40 mg/kg; irrigation water, up to 255 μg/L), and underscore the potential human and environmental risks associated with the presence of As in the country. This review highlights the importance of focusing research on understanding the occurrence, origin and distribution of As in Colombia to better understand its environmental and public health impact. -- Highlights: • Information about arsenic (As) studies in Colombia is provided. • Occurrence of As in Colombia. • Compilation help to increase knowledge of As presence in Latin America. • Need for more research on the occurrence, origin, distribution, speciation and remediation of As in Colombia. -- This review communicates the untold story of arsenic in Colombia and draws attention to the need for more rigorous research on the metalloid. It also contributes to the information available on As in Latin America

Digitally intensive DC-DC converter for extreme space environments, Phase II

Data.gov (United States)

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...

Zero-voltage DC/DC converter with asymmetric pulse-width modulation for DC micro-grid system

Science.gov (United States)

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.

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....

Pulse-width modulated DC-DC power converters

CERN Document Server

Kazimierczuk, Marian K

2008-01-01

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

Digitally intensive DC-DC converter for extreme space environments, Phase I

Data.gov (United States)

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...

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....

Active Teachers - Active Students

DEFF Research Database (Denmark)

as an initiative from the Polytechnic in Nantes, France and the University the Los Andes in Bogota, Colombia. The objective was to start a world wide collaboration allowing teachers in engineering to learn from each other about their experiences with active learning. In this thirteenth edition, ALE joins forces...... with the International Research Symposium on Problem Based Learning (IRSPB) and the International Symposium on Project Approaches in Engineering Education (PAEE) to organise the first International Joint Conference on the Learner in Engineering Education (IJCLEE 2015) hosted by Mondragon University, in San Sebastian...

Asumiendo juntos los retos: calidad de vida en familias de jóvenes con discapacidad intelectual

OpenAIRE

Viviana Aya Gómez; Leonor Córdoba

2013-01-01

Antecedentes. La calidad de vida familiar se ha convertido enun área de creciente interés en los años recientes.Objetivo. Describir y comprender la calidad de vida de 18familias de jóvenes con discapacidad intelectual en Bogotá,Colombia.Material y métodos. Estudio mixto a través de la Escala deCalidad de Vida Familiar y entrevistas semiestructuradas, paraconstruir con cada familia el Mapa de Calidad de Vida Familiar.Resultados. Los factores de calidad de vida familiar fueronvalorados como f...

The Extermination of the Civic Movement in the Eastern Region in Antioquia

Directory of Open Access Journals (Sweden)

Carlos Hernando Olaya Rodríguez

2017-01-01

Full Text Available During the 1950’s and the 1960’s, a large rural migration to the cities took place in Colombia, as a result of the heinous acts of violence, which the country experienced in that time, and by the attraction of agricultural workers toward the industrial sector, which is the producer of commodities and which was spread notoriously in that moment. This led to the increase in the demand of electricity, for such a reason, the utility companies of Medellin, Bogota, and Cali, designed great projects of hydroelectric generation.

Technology Applied to ELT: Reviewing Practical Uses to Enhance English Teaching Programs

Directory of Open Access Journals (Sweden)

Javier Rojas Serrano

2007-12-01

Full Text Available In this paper, the author reports on some of the areas of technology currently used in the teaching and learning of languages, and reviews some of the uses of technological tools that are present in the English Adult Program and activities carried out at The Centro Colombo Americano (CCA in Bogota, Colombia. After briefly describing what is being applied worldwide in terms of what is being done at the CCA, some suggestions are offered in order to enhance the English teaching and learning processes through the use of new technologies.

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...

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.

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...

Light weight, high power, high voltage dc/dc converter technologies

Science.gov (United States)

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.

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...

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...

Plan Colombia or development as security

Directory of Open Access Journals (Sweden)

Juan Pablo Guevara Latorre

2015-01-01

the most relevant policy for the construction of the State in 21st-century Colombia from a critical standpoint. The document makes it possible to show that Plan Colombia is a privatized form of development, interpreted in terms of security based on an incomplete understanding of the Colombian conflict that prevails into our present

High-power three-port three-phase bidirectional DC-DC converter

NARCIS (Netherlands)

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

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...

Modeling and analysis of fractional order DC-DC converter.

Science.gov (United States)

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.

Proyecto Ensamblando en Colombia

OpenAIRE

Kreime, Pablo; Gómez Morales, Yuri Jack; Ashmore, Malcolm; Miranda Canal, Néstor; Pérez Bustos, Tania; Vinck, Dominique; Amaya, José Antonio; Carvajal Marín, Luz Mery; Castro-Gómez, Santiago; Camargo Uribe, Juan Arturo; Dávila Dávila, Juan Manuel; Sebastián, Díaz Ángel; Duque Muñoz, Lucía; Durán-Sánchez, María Fernanda; García Álvarez, Claudia María

2013-01-01

Los dos volúmenes de esta obra reúnen los resultados del proyecto ganador de la «Convocatoria nacional de proyectos bicentenario 1810-2010 “Historia social de la ciencia, la tecnología y la innovación en Colombia: ciudadanía, saberes y nación”», lanzada por Colciencias en el 2009. El proyecto, titulado «Ensamblado en Colombia: producción de saberes y construcción de ciudadanías» se propuso estudiar la manera como se constituyen en el presente y se han constituido en el pasado «asuntos de inte...

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...

A high voltage ratio and low ripple interleaved DC-DC converter for fuel cell applications.

Science.gov (United States)

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.

DC Rocks! Using Place-Based Learning to Introduce Washington DC's K-12 Students to the Geosciences

Science.gov (United States)

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

A comparison of the migration process to an urban barrio and to a rural community: two case studies.

Science.gov (United States)

Flinn, W L; Cartano, D G

1970-01-01

The results of 2 case studies on migration in Colombia are outlined and compared. The 1st study examines inmigration to a shantytown, El Carmen, in Bogota. The 2nd study involves inmigration to a community in the eastern interior of Colombia, Granada. Migrants' motives, paths of migration, and personal characteristics are examined, suggesting hypotheses for future studies. Economic reasons were most often listed as motives for moving by both the residents of Granada and El Carmen. The type of economic motives varied greatly between the 2 communities. Reasons such as "looking for land," "establishing a business," or "to find a better life" ranked high in importance among Granada residents. These motives, along with the flight from violence, indicate that the independence provided by land and small business affords the inmigrants to Granada a certain security. Inmigrants to El Carmen were seeking employment. Only 34% of the migrants to El Carmen made 1 or more moves before settling in Bogota. 90% of the rural to rural migrants made 1 or more stops before moving to Granada. 68% of the migrants to El Carmen were born within 100 miles of Bogota while only 18% of the migrants to Granada were born within a 100 mile radius of the community. The usual pattern of the migrant to Granada was to move to a neighboring village, town, or city regardless of whether it was closer to Granada or not. The majority of inmigrants to Granada moved from distances greater than 100 miles. Over 70% of the inmigrants were born in towns and villages of more than 2000 population. If a nucleus of 10,000 inhabitants or more are considered urban, then 46% of the rural to rural migrants resided in urban areas prior to moving to Granada. This suggests that a sizable proportion of the migration to Granada is really urban to rural frontier. Studies done in Colombia and Brazil indicate that migrants to rural areas have a lower educational level than migrants to urban areas. Data from El Carmen and

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.

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.

Critical revision of the technical aspects of sanitation of the Bogota river 1994 project

International Nuclear Information System (INIS)

Giraldo Eugenio

1996-01-01

A moral obligation exists on the part of the human societies of having designed to remove the contamination the environment that has been commended to manage and that it represents the inheritance that guarantees the survival of the species in the earth planet. It exists a growing recognition of this imperious necessity at the present time on the part of all the societies in the world that immediately opens the roads for the political exploitation of so praiseworthy feelings. Paradoxically, the environmentalist feelings don't always redound in a better protection for the nature and the environment, natural or urban. The reparation plan to continue for the Decontamination of the Bogot River; hired by the concession system the first stage of the same one, it is summarized in making three plants of treatment of located residual waters, each one of them in the outlets on the Bogota river of the main basins of drainage of the sanitary sewer system of the city. The treatment plants are of a conventional technology, mud activated that basically are designed to remove 90% of the contamination for organic matter that takes the sanitary sewer system of the respective basin. This level of achieved treatment is denominated in the technical literature as secondary treatment

Plan Colombia: The View from the Presidential Palace

Science.gov (United States)

2001-05-01

la violencia , in which liberals and conservatives kill each other in order to seize control of the government. Of course, there have been efforts to...Colombia for some 40 years. I have been in the Colombian Senate for 8 years. I’ve traveled all over Colombia. I’ve been familiar with Colombia’s...country because of la violencia in the early Fifties. Colombia, since the end of that unfortunate turn, has enjoyed a robust democratic system under which

Abejas englosinas de Colombia (Hymenoptera: Apidae I. Claves ilustradas Abejas englosinas de Colombia (Hymenoptera: Apidae I. Claves ilustradas

Directory of Open Access Journals (Sweden)

Bonilla Gómez María Argenis

1992-09-01

Full Text Available One hundred and eight euglossine bee species are registered for Colombia, distributed in five genera: Aglae (1, Eufriesea (30, Euglossa (60, Eulaema (13 and Exaerete (4. New records for Colombia include: Eufriesea auripes, Ef. dressleri, Ef. fragrocara, Ef. xantha, Euglossa viridis, Eg. azureoviridis, Eg. cognata, Eg. singularis, EI. boliviensis, EI. seabrai and EI mocsaryi. Keys are given for males and females of Aglae, Exaerete, Eulaema and Eufriesea and for males of Euglossa of the 108 Colombian euglossines. A key for the subgenera of Euglossa is presented by the first time. Revisando diferentes fuentes de literatura y colecciones de abejas en Colombia y el exterior se encontró para Colombia un total de 108 especies de abejas de la subfamilia Euglossinae repartidas en 5 géneros: Aglae (1 especie, Eufriesea (30 especies, Euglossa (60 especies, Eulaema (13 especies y Exaerete (4 especies. Se registran por primera vez para Colombia 11 especies de abejas euglosinas: Eufriesea auripes, Ef. fragrocara, Ef. dressleri, Ef. xantha, Euglossa viridis, Eg. cognata, Eg. singularis, Eg. azureoviridis, Eulaema boliviensis, EI. seabrai y EI. mocsaryi. Se presentan claves para las 108 especies de los 5 géneros así, machos y hembras de Eufriesea, Exaerete y Aglae y los machos de Euglossa y por primera vez una clave para los subgéneros de Euglossa.

Homopolar dc motor and trapped flux brushless dc motor using high temperature superconductor materials

Science.gov (United States)

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.

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...

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.

Application handbook for a Standardized Control Module (SCM) for DC-DC converters, volume 1

Science.gov (United States)

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.

Application handbook for a Standardized Control Module (SCM) for DC-DC converters, volume 1

Science.gov (United States)

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.

Phytochemical research of leaves and flowers of Smallanthus pyramidalis (Triana) H. Rob. (Arboloco) and its use in the recovery of wetlands in Bogota

International Nuclear Information System (INIS)

Guzman Avendano, Antonio J; Barrera Adame, Diana A.

2011-01-01

This research focused on the phytochemical characterization of the species Smallanthus pyramidalis (Triana) H. Rob. in order to identify the secondary metabolites of flowers and leaves. This is due to the importance these trees on the sustainable development of the wetlands in the Sabana de Bogota, and its possible application as a promising species in the use and conservation of these ecosystems. We performed preliminary chemical tests, fractionation using conventional techniques, identification of physical and chemical properties, and structural analysis using spectroscopic and spectrometric techniques, such as UV, 1H-RMN, 13C-RMN and GC-MS. We identified alkane-type compounds, steroids, terpenoids and flavonoids mainly, and their role in the plant and the ecosystem.

Chemical speciation of Pb, Ni Cr, Cu, Co and V in two natural soils and in an antropic agricultural soil contaminated by irrigation with the polluted Rio Bogota waters in its High Basin

International Nuclear Information System (INIS)

Matamoros, Adriana; Vargas, O; Mejia, L

1999-01-01

Traditional and continuous irrigation with the highly polluted waters of Rio Bogota in its upper basin has induced in soils, grasses and crops grown next to the river, a gradually increasing accumulation of highly toxic elements like Pb, Ni, Cr, Cu, Cd, Co, V and some others, which represents a real and very high risk for public health whenever grasses and edible crops growing on them absorb these elements above critical or permissible limits. To evaluate the magnitude of this problem three different soils of the Sabana were subjected to the chemical speciation procedure proposed by Tessier (1979) in order to determine: 1) the total content of essential and/or structural elements like Al, Fe, Ca, K, P, Mn and Ti, and the trace elements Pb, Ni, Cr, Cu, Cd, Co and V accumulated through time in the soils; 2) the relative proportion on which each one of them are linked to the different components or fractions of soils (ex. exchangeable, CO 3 , Fe/Mn oxides, O.M. and sulfides, and residual fraction) and 3) the bioavailability or amount of each that could be really absorbed by plants or able to go down to the underground water. Results showed in general for all soils normal values for the essential and/or structural elements and high to very high levels of Pb, Ni, Cu, Cd, Cr, Co y V, higher in Jardines de Colombia and Las Parcelas farms soils than in el Recreo farm soils. This situation is aggravated by the relatively high mobility and high concentration and bioavailability of some of these elements, which increase the risk for public health and the possibility of its migration down to the underground waters

Design of PI Controlled Non Isolated Bidirectional DC to DC Converter for Electric Vehicle Application

Science.gov (United States)

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.

Application of Distributed DC/DC Electronics in Photovoltaic Systems

Science.gov (United States)

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.

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...

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...

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.

Ética filosófica en Colombia. 1990-2000

OpenAIRE

Palacio, Martha

2005-01-01

El siguiente artículo presenta las conclusiones de la investigación realizada sobre la ética filosófica en la última década del siglo XX en Colombia. Dentro del proyecto investigativo de la Facultad de Filosofía de la Universidad Santo Tomás de Bogotá, Colombia, orientado al estudio y análisis de la historia de las ideas en América latina y Colombia, la investigación llevada a cabo buscó definir y aclarar el lugar que ocupa la ética filosófica en la historia de las ideas en Colombia. Para tal...

Observatorio de Política Internacional I. COLOMBIA - El proceso de paz en sala de emergencia

OpenAIRE

Neira Fernández, Enrique

2007-01-01

Observatorio de Política Internacional I. COLOMBIA (Neira Fernández, Enrique) RECIENTES Año 2008 Colombia. Cerca el fin del paramilitarismo Colombia. Cerca el fin de las Farc Colombia. Conflicto armado y desarrollo humano Colombia. Política exterior Colombia. Inicia el 2008 con buen pie Año 2007 Colombia. Tras las pasadas elecciones Colombia. El espectro de las próximas elecciones Colombia. La garrocha de Uribe Colombia. III Parapolíticos Colombia. II...

75 FR 22207 - Importation of Papayas From Colombia and Ecuador

Science.gov (United States)

2010-04-28

.... APHIS-2008-0050] RIN 0579-AC95 Importation of Papayas From Colombia and Ecuador AGENCY: Animal and Plant... Colombia and Ecuador into the continental United States. The conditions for the importation of papayas from Colombia and Ecuador include requirements for field sanitation, hot water treatment, and fruit fly trapping...

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.

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...

Egr2 induced during DC development acts as an intrinsic negative regulator of DC immunogenicity.

Science.gov (United States)

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.

Aplicación del trabajo en equipo en colombia, adelantos investigativos

Directory of Open Access Journals (Sweden)

Víctor Manuel Ardila-Soto

2004-01-01

Full Text Available This article is the result of an empirical research conducted on the concept of teamwork with managers of companies manufacturing in the cities of Bogota, Cali, Medellin, Barranquilla, Bucaramanga and Cucuta, based on a conceptualization adjusted according to the contribution made by different authors (Mueller, Procter, Buchanan, 2000; Knights and McCabe, 2000; Sewell, 1999; Tranfield et al. 1999; Katzenbach and Smith, 1993 Montebello 2000, divulgándose as a result the Colombian case with regard to this concept, such as social science research contribution in relation to teamwork.

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.

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...

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)

75 FR 47199 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-9-10 Series Airplanes, DC-9-30...

Science.gov (United States)

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...

Tendencias del suicidio en Colombia, 1985-2002 Suicide trends in Colombia, 1985-2002

Directory of Open Access Journals (Sweden)

Ricardo Cendales

2007-10-01

Full Text Available OBJETIVOS: Describir las tendencias de la mortalidad por suicidios en Colombia en el período de 1985 a 2002, analizar su comportamiento según el sexo, el grupo de edad y el mecanismo de lesión y calcular los años de vida potencial perdidos (AVPP por suicidios en ese período. MÉTODOS: Se calcularon las tasas de mortalidad crudas, específicas por edad y sexo y ajustadas por la edad, a partir de la información de mortalidad y población de las bases de datos oficiales del Departamento Administrativo Nacional de Estadística de Colombia. Se estimaron los AVPP, corregidos por el impacto social, la edad y la mala calidad de los registros de muertes. La tabulación de los resultados se realizó según los códigos X600-X849 y Y870 de la décima revisión de la Clasificación Estadística Internacional de Enfermedades y Problemas Relacionados con la Salud (CIE-10 y los códigos E950-E959 de la novena revisión (CIE-9. RESULTADOS: Se observó un aumento considerable en las tasas de suicidios en Colombia a partir de 1998, particularmente en la población de adultos jóvenes y en hombres. Las tasas más altas en los hombres se observaron en los grupos de 20 a 29 años y de mayores de 70, con un incremento en el tiempo. En las mujeres, las tasas más altas se registraron en el grupo de 10 a 19 años. La proporción de AVPP por suicidios aumentó de 0,81% en 1981 a 2,20% en 2002. En los hombres, los principales mecanismos de lesión fueron las heridas por armas de fuego y explosivos, el ahorcamiento y el envenenamiento, con un aumento relativo del ahorcamiento, mientras que en las mujeres fue el envenenamiento. CONCLUSIONES: Se confirmó la tendencia ascendente en la tasa de suicidios en Colombia, especialmente en el segmento de la población laboralmente activa, lo que conlleva un drástico incremento en los AVPP.OBJECTIVES: To report trends in mortality from suicide in Colombia from 1985 to 2002 by sex, age group, and method, and determine the

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 ...

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

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.

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....

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....

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.

Research on Two-channel Interleaved Two-stage Paralleled Buck DC-DC Converter for Plasma Cutting Power Supply

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...

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%

Pulsed-DC selfsputtering of copper

Science.gov (United States)

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%.

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.

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

DC-Compensated Current Transformer.

Science.gov (United States)

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.

High voltage dc cables

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.

Estimating of precursors and behavior of acid precipitation wet and dry, in the north of Bogota

International Nuclear Information System (INIS)

Garcia Lozada, Hector; Natal, Angelica; Esquivel, Antolinez; Diaz Alvarez, Cristian Julian

2004-01-01

Measurements of pH of the wet deposition were made in the north sector of Bogota, in two manual stations located to the East (Sans Facon) and to the West (Agustiniano Norte) of the northern highway, which served as the axis of the studied area, with an approximated extension of 54 km 2 . By means of an algorithm based on the model CORINAIR, the emissions of the precursors of acid rain were obtained: NOx (7665 T/y) and SO 2 (109 T/y). Between December 2002 and April 2003, 35 rain events were evaluated and it was found that 70% of the 17 rain water samples in the eastern sector and 83% of the 18 ones in the western sector, as viewed from the northern highway, show a pH smaller than 5.6, considered to be the natural value of the pH in rain. In the settled dust, to the west of the highway, the pH reached a value of 7.47, that to the east reached 7.78, while along monitoring lines the pH ranged between 5.71 and 6.70

Comparative evaluation of bidirectional dual active bridge DC-DC converter variants

NARCIS (Netherlands)

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

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)

Medición del comercio intraindustrial Colombia - Estados Unidos 1995-2005

OpenAIRE

Caicedo Marulanda, Carolina

2010-01-01

Este documento analiza la existencia de comercio intraindustrial entre Colombia y Estados Unidos, usando la información contenida en la base de datos BACI del CEPII para el periodo comprendido entre 1995 y 2005. La pertinencia de establecer una medición de los flujos de comercio intraindustrial entre Colombia y Estados Unidos radica fundamentalmente en la importancia relativa que representa Estados Unidos como socio comercial para Colombia. El comercio bilateral entre Colombia y Estados c...

Modular Power System Configured with Standard Product Hybrid DC-DC Converters, Phase II

Data.gov (United States)

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...

DIAGNOSTIC/PROGNOSTIC EXPERIMENTS FOR CAPACITOR DEGRADATION AND HEALTH MONITORING IN DC-DC CONVERTERS

Data.gov (United States)

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...

Simulating and Testing a DC-DC Half-Bridge SLR Converter

Science.gov (United States)

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

Efficient Visible Light Communication Transmitters Based on Switching-Mode dc-dc Converters

Science.gov (United States)

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

DC-Voltage Fluctuation Elimination Through a DC-Capacitor Current Control for DFIG Converters Under Unbalanced Grid Voltage Conditions

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...

U.S. Support to Plan Colombia: A Heading Check

National Research Council Canada - National Science Library

Buckley, Kevin

2004-01-01

.... For some Latin American countries like Colombia these ideals fall quite short of reality. Colombia is plagued by internal problems which restrict its ability to adequately govern its population and territory...

The public health context of violence in Colombia.

Science.gov (United States)

Garfield, Richard; Llanten Morales, Claudia Patricia

2004-10-01

Among the countries of the Americas, Colombia has the highest level of deaths due to homicides and armed conflict. The objective of this research was to combine and contrast information from various sources on deaths due to violence in Colombia in order to identify major trends in violence in the country and to compare those trends with those in other nations of the Americas. We drew together information from a wide array of sources, including the Government of Colombia, Colombian forensic institutions, nongovernmental organizations, and international research centers. We considered the impact of the violence on mortality as well as in such areas as nonfatal injuries, displacement of persons, and kidnappings. While there have been many deaths in Colombia directly related to military conflict, there have been many more deaths and injuries as an indirect result of war. The highest levels of deaths directly related to violence occurred during the 1990-1995 period. Although deaths due directly to armed conflict declined in the late 1990s, the related events of kidnappings and displacement did not. Efforts to reduce the violence-related suffering in Colombia must consider both direct and indirect causes of mortality as well as nonfatal outcomes such as kidnappings and displacement.

AC Voltage Control of DC/DC Converters Based on Modular Multilevel Converters in Multi-Terminal High-Voltage Direct Current Transmission Systems

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.

First Implementation of a Two-Stage DC-DC Conversion Powering Scheme for the CMS Phase-2 Outer Tracker

CERN Document Server

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.

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)

Natalidad y fecundidad, Colombia, 2001

OpenAIRE

León A, Alba Luz; Ocampo A, Leidy Johanna; Spath P, Doris Estella; Agudelo G, Héctor Byron; Grisales R, Hugo

2006-01-01

Se presenta la natalidad, la fecundidad y los nacimientos vivos en Colombia en el año 2001 con base en la totalidad de los registros de nacidos vivos del Departamento Administrativo Nacional de Estadísticas (dane) (724.236). La población de Colombia, calculada a mitad de período, se dividió en ocho categorías de municipios de acuerdo con el tamaño poblacional, según la Ley 617/2001. No se presentaron diferencias importantes entre las variables afines a las características del recién nacido po...

Descubrir el universo desde Colombia

OpenAIRE

Duque Escobar, Gonzalo

2009-01-01

Los dos hechos científicos más relevantes en la corta historia de Colombia, son la Real Expedición Botánica del Nuevo Reino de Granada y la Misión Corográfica. Hoy cuando los astrónomos, entre otros asuntos que se ubican en la frontera del conocimiento, intentan conocer la geometría del espacio, la naturaleza de la materia oscura y los misterios del tiempo, en Colombia nuestros científicos tienen pendiente entre otros aportes para la construcción de la Nación, apoyar tareas fundamentales y es...

Research of digital controlled DC/DC converter based on STC12C5410AD

Science.gov (United States)

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.

On-grid and Off-grid Operation of Multi-Input Single-Output DC/DC Converter based Fuel Cell Generation System

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.

IDRC in Colombia

International Development Research Centre (IDRC) Digital Library (Canada)

oceans, wastewater from poor urban com- munities could be treated and used to gener- ate energy. Mexican researchers lead the testing of wastewater treatment systems in Brazil, Colombia, Chile, Honduras, and. Mexico to identify the most appropriate technologies. Alternative energy (through biogas) could eventually ...

Urban Violence Reduction and Citizen Security in Brazil, Colombia ...

International Development Research Centre (IDRC) Digital Library (Canada)

Urban Violence Reduction and Citizen Security in Brazil, Colombia, Mexico, and ... The work will be conducted in Brazil, Colombia, Mexico, and South Africa, which are ... Minister Bibeau announces appointments of IDRC's President and new ...

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

The application of standardized control and interface circuits to three dc to dc power converters.

Science.gov (United States)

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.

Design of the DC-DC power stage of the capacitor charger for MAXIDISCAP power converters

CERN Document Server

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.

Risk factors and prevalence of osteoporosis in premenopausal women from poor economic backgrounds in Colombia

Directory of Open Access Journals (Sweden)

Londono J

2013-07-01

Full Text Available John Londono,1 Paula Valencia,1 Ana María Santos,1 Luisa F Gutiérrez,2 Roberto Baquero,1 Rafael Valle-Oñate1,3 1Rheumatology Department, Universidad de La Sabana, Chía, Cundinamarca, Colombia; 2Preventive Care Ltd, Research Unit, Chía, Cundinamarca, Colombia, 3Rheumatology Department, Hospital Militar Central, Bogotá, DC, Colombia Introduction: The prevalence of osteoporosis in premenopausal women along with associated risk factors has not been well elucidated. Recent studies have shown that poverty is a risk factor for osteoporosis. Objective: To determine the prevalence of osteoporosis and its risk factors in a group of premenopausal women of poor economic background in Colombia. Materials and methods: The study comprised 1483 women between 35 and 53 years of age with at least one risk factor for osteoporosis. Demographic characteristics, reproductive factors, comorbidities, and risk factors for osteoporosis were evaluated. Lumbar vertebrae (L2–L4 and the femur neck were assessed using dual-energy X-ray absorptiometry. Results: Of the 1483 patients, 1443 (97.3% had at least one risk factor for osteoporosis and 40 (2.7% had no risk factors. Patients with one risk factor were referred to have a dual-energy X-ray absorptiometry scan, which 795 women completed. Osteopenia was found in 30.5% and osteoporosis in 4.8% of these women. The majority of these women were homemakers, and 18.5% of the patients with osteoporosis were also illiterate (P < 0.001. The risk factors identified in this population were: hypothyroidism (odds ratio [OR] = 5.19, 95% confidence interval [CI]:1.6–16, age over 45 years old (OR = 1.13, 95% CI: 1.0–1.2, a history of malnutrition or low birth weight (OR = 2.35, 95% CI: 1.0–5.2, or early-onset menopause (OR = 3.4, 95% CI: 1.6–7.2. Conclusion: Premenopausal Colombian women from impoverished areas showed increased rates of osteopenia and osteoporosis compared with the data described in the current literature

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...

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...

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.

Design and modelling of high gain DC-DC converters for fuel cell hybrid electric vehicles

Science.gov (United States)

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.

Barriers to combating human trafficking in Colombia

OpenAIRE

Wilcox, Daniel Joseph

2015-01-01

Approved for public release; distribution is unlimited Despite international and domestic policies and programs intended to combat human trafficking, Colombia remains one of the countries with the highest instances of human trafficking in the Western Hemisphere. Factors contributing to human trafficking in Colombia, such as internal violence and displacement, drug trafficking, a weak central government, and widespread corruption, have overpowered what energies the government marshaled agai...

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...

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...

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

Contributions to Industrial Development of Science and Technology Institutions in Colombia and Opportunities for Bilateral Cooperation.

Science.gov (United States)

1979-12-01

Source: Ciencia , Tecnologia , y Desarrollo, Bogota, 2 (1>: 142, February- March, 1978 Many suggestions have been offered as to steps that could be taken...quite sharp. Studies prepared for COLCIENCIAS and FES, for example, have iden- tified the following problem areas ( Ciencia , Technologia, y Desarrollo...representing the official opinion or policy of the United States Government. F:, PREFACE This report analyzes (.& Y the characteristics and capabilities of the

Street youth in Colombia: lifestyle, attitudes and knowledge.

Science.gov (United States)

Ruiz, J

1994-01-01

Gamines in Bogota, Colombia, are youths who live on the streets sometimes keeping loose family ties. They belong to informal gangs, use drugs, and survive by doing itinerant informal sector work, begging, and stealing. The New Life Program (NLP) of the Corporacion SOS Aldea de Ninos worked with three other agencies to investigate the lifestyle, attitudes, and knowledge of gamines about HIV/STDs for the purpose of designing AIDS/STD educational activities for the population. Focus group discussions and educational activities were conducted with 12 girls and 18 boys aged 14-25 years who had started living in NLP's shelter while working on the streets. Participants had spent an average of 7 years on the street typically from age 10. Concentrating primarily upon daily survival, these youths act on the basis of intuition and emotions. Verbal communication is essential to gain and maintain their trust. Although their sexual lives are influenced by the family of origin, institutions in which they have resided, and peers, and their daily lifestyles have much influence. Steady partners are sought for affection and romance, while sexual intercourse is had for pleasure and to satisfy biological need. Some homosexuality and prostitution are tolerated. Gangs also gang-rape and expel members thought to be traitors. The idea of birth control exists among the girls, but the boys overwhelmingly reject condom use. The boys got information on sex from prostitutes, erotic magazines, and adults, but girls rarely talk about sex. Many have had STDs and are generally aware about AIDS, but misinformed about transmission modes, symptoms, and treatment. The boys were especially negative about meeting a person with AIDS. Overall, the youths did not perceive themselves as being at risk for HIV infection. Participants also strongly distrusted the health system because many had been turned away for being dirty or received only callous treatment. The author concludes that we must acknowledge that

DC-DC Type High-Frequency Link DC for Improved Power Quality of Cascaded Multilevel Inverter

Science.gov (United States)

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.

Wide Temperature Range DC-DC Boost Converters for Command/Control/Drive Electronics, Phase I

Data.gov (United States)

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...

DC Microgrids—Part II

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...

The century of the Petroleum in Colombia

International Nuclear Information System (INIS)

Carta Petrolera

1999-01-01

A recount of the big changes is made with hydrocarbons in Colombia during the X X century. The X X century it meant everything for Colombia in oil matter. In this century it took off and it consolidated their industry of the hydrocarbons and with her great part of the industrialization process and development of the country. It is undeniable that the petroleum was one of the big main characters of the century X X and Colombia has not been unaware to the sways of a highly changing industry. The creation of the OPEC, the warlike conflicts, the times of high and low prices, the technological advances, the processes of energy integration and the mega coalitions are hardly some of the ingredients that seasoned the Oil Industry in the years 1900

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...

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...

Integrating DC/DC Conversion with Possible Reconfiguration within Submodule Solar Photovoltaic Systems

Science.gov (United States)

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

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)

Impresiones de los Mexicanos sobre la imagen país de Colombia

Directory of Open Access Journals (Sweden)

Lina María Echeverri Cañas

2014-08-01

Full Text Available La imagen país de Colombia ha sido objeto de discusión en los campos de los negocios internacionales y el marketing territorial. Colombia es un país con un posicionamiento tradicional asociado al narcotráfico y al café, situación que ha llevado a los gobiernos de la última década a definir nuevas estrategias que ayuden a mejorar la reputación del país en mercados internacionales. Sin embargo, sus esfuerzos han sido de poco impacto porque la imagen país de Colombia todavía mantiene una asociación histórica negativa resultado del narcotráfico. En este sentido, el presente artículo aborda los resultados de una investigación realizada sobre las impresiones que tienen los mexicanos que han visitado y no han visitado a Colombia. Se eligió a México porque es el segundo emisor de turistas hacia Colombia procedentes de Norteamérica. Por medio de una investigación empírica aplicada a una muestra de 190 mexicanos mayores de 18 años, se encontró que el posicionamiento se mantiene negativo y se asocia al país con drogas, terrorismo, inseguridad y corrupción. Dicha percepción contrasta con un atributo que se destaca en el estudio, y es que se asocia a Colombia con la amabilidad de su población. Los resultados del estudio se obtuvieron finalizando el 2013. Palabras clave: Asociación; Colombia; imagen país; México; percepción; visitantes.Mexicans' impressions of Colombia's country imageAbstractThe country image of Colombia has been discussed in the fields of international business and territorial marketing. Colombia is a country with a positioning associated with drug trafficking and coffee. This situation has led governments in the last decade to define new strategies to help improve Colombia’s reputation in international markets. However, its efforts have been of little impact, because the image of Colombia country still maintains negative due to its historical association. In this sense, this article discusses the results

Retrospective evaluation of early and aggressive decompressive craniectomy (DC) for severe head injury. Was that DC necessary?

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)

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%.

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...

High-Efficiency High Step-Up DC-DC Converter with Dual Coupled Inductors for Grid-Connected Photovoltaic Systems

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...

Design and Implementation of Anti-windup PI Control on DC-DC Bidirectional Converter for Hybrid Vehicle Applications

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.

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.

Responsabilidad ambiental sistémica de los programas académicos de pregrado de contaduría pública con registro de alta calidad en Bogotá D.C.

OpenAIRE

Pereira Sánchez, Omaira; Sanabría Léon, Gilma

2017-01-01

287 páginas : ilustraciones, gráficos, tablas. Esta investigación propone como objetivo general, evaluar los contenidos temáticos sobre responsabilidad ambiental sistémica de los contadores públicos, asumidos en los programas académicos con registro de alta calidad en Bogotá D.C., y su relación con la normatividad en educación ambiental en Colombia. La metodología de la investigación es de tipo cualitativo y los actores que aportaron información y que conforman la población objeto de estud...

Current Mode Control for LLC Series Resonant DC-to-DC Converters

OpenAIRE

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...

Strategic ecosystems of Colombia

International Nuclear Information System (INIS)

Marquez Calle German

2002-01-01

The author relates the ecosystems in Colombia, he makes a relationship between ecosystems and population, utility of the ecosystems, transformation of the ecosystems and poverty and he shows a methodology of identification of strategic ecosystems

Floating high step-down stacked dc-dc converter based on buck-boost cells

NARCIS (Netherlands)

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

UNJUK KERJA PENGUBAH TEGANGAN DC-DC TOPOLOGI BOOST DENGAN NILAI INDUKTANSI DAN KAPASITANSI YANG DIOPTIMASI PADA KEADAAN TRANSIEN

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 Ώ dan tegangan input 12 volt adalah 1038 μF dan 11,9 mH

Rhesus macaque and chimpanzee DC-SIGN act as HIV/SIV gp120 trans-receptors, similar to human DC-SIGN

NARCIS (Netherlands)

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

Loodushariduse mammutkongress Colombias / Aarne Tõldsepp

Index Scriptorium Estoniae

Tõldsepp, Aarne

2009-01-01

Sel suvel toimunud rahvusvahelisest matemaatika- ja loodushariduse kongressist Colombia ajaloolises sadamalinnas Cartagenas, mille peakorraldajaks oli 19 aastat tagasi Valgevenest Colombiasse emigreerunud professor Juri Orlik

The Chaotic-Based Control of Three-Port Isolated Bidirectional DC/DC Converters for Electric and Hybrid Vehicles

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.

78 FR 60191 - United States-Colombia Trade Promotion Agreement

Science.gov (United States)

2013-10-01

... Trade Promotion Agreement AGENCY: U.S. Customs and Border Protection, Department of Homeland Security... tariff treatment and other customs-related provisions of the United States- Colombia Trade Promotion... States-Colombia Trade Promotion Agreement (``CTPA'' or ``Agreement''), and on June 28, 2007, the Parties...

State-of-the-art of the historical seismology in Colombia

Directory of Open Access Journals (Sweden)

E. J. Salcedo Hurtado

2004-06-01

Full Text Available In Colombia are available a discreet number of historical seismology investigations, dating back 50 years. This paper reviews basic information about earthquakes studies in Colombia, such as primary sources, compilation of descriptive catalogues and parametric catalogues. Father Jesús Emilio Ramírez made the main systematic study before 1975. During the last 20 years, great earthquakes hit Colombia and, as consequence, historical seismology investigation was developed in the frame of seismic hazard projects.

A Markovian Approach Applied to Reliability Modeling of Bidirectional DC-DC Converters Used in PHEVs and Smart Grids

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.

Corporate Governance in Colombia. Current trends Gobierno corporativo en Colombia. Tendencias actuales

Directory of Open Access Journals (Sweden)

Sandra Gaitán Riaño

2009-12-01

Full Text Available This document provides a look at The Colombian Corporate Governance System, from the promulgation of the Law 275 of 2001. The guidelines of international standards on corporate governance are commented and compared with the Colombian legislation. Features of the Code of Good Governance in Colombia are evaluated in which look for get competitiveness, sustainability, and deepening of the stock market, according to the principles of the OECD. It is presented a comparative study make in the country during 2002 and 2007 where there were deficiencies in the codes of the company's investor protection, the role of boards and transparency of information. The author shows a study about the annual penetration in adopting good governance practices in Colombia and concludes that the private financial sector is concerning to adopt them. That study present that 60% of companies have made no changes to the code since its inception.La Ley 275 de 2001 determinó el sistema de Gobierno Corporativo colombiano. El presente documento permite una mirada desde su entrada en vigencia. Se comentan los lineamientos de los estándares internacionales en esta materia y se comparan con la legislación nacional. Se evalúan las características del Código de Buen Gobierno en Colombia donde se promueve el logro de la competitividad, sostenibilidad y profundización del mercado accionario con base en los principios de la OCDE. Se cotejan estudios realizados en el país (2002, 2007 donde se observa deficiencia en los códigos de las empresas en cuanto a la protección del inversionista, el papel de las juntas directivas y la transparencia en la información. Se expone también cómo ha sido la penetración anual en la adopción de prácticas de buen gobierno en Colombia y la preocupación de empresas privadas del sector financiero por adoptar dichas prácticas. El 60% de las organizaciones no han efectuado modificaciones al código desde su puesta en marcha.

Violencia y salud en Colombia

Directory of Open Access Journals (Sweden)

Saúl Franco Agudelo

1997-02-01

Full Text Available La violencia en Colombia parece incontenible. A las masacres y asesinatos colectivos, de una crueldad desconcertante, se suman los secuestros y desapariciones, el maltrato de niños y ancianos y las violaciones de adolescentes. Cada día, sin tregua, los colombianos son espectadores o víctimas de atracos callejeros y de discriminación racial, sexual y socioeconómica. Sin quererlo, se convierten en agentes de agresiones en el transporte urbano, el hogar, la escuela y el trabajo. Colombia tiene las tasas de mortalidad por homicidio más altas del mundo. Independientemente de la enorme sobrecarga institucional que impone a los servicios de salud y medicina legal, la violencia constituye actualmente en Colombia el principal problema de salud pública. Para hacerle frente, el sector de la salud debe elaborar políticas y financiar acciones; crear nuevos procesos de formación de personal, poner en marcha procesos de educación pública, y dedicar mayor esfuerzo y creatividad al campo de la investigación, que hasta ahora ha dado respuestas importantes pero aún insuficientes. Al reflexionar sobre la violencia, que es la sustitución de toda argumentación por la fuerza, es necesario ubicarla en el contexto de la vida y la salud. No se pretende solo racionalizarla, y menos aún sustituir la acción por la palabra o por las reflexiones, sino tratar de comprenderla a fondo con el objeto de buscarle alternativas. En el presente artículo se analiza, con esta finalidad, el tema de la violencia en Colombia, principalmente desde el punto de vista de su efecto en la salud de los colombianos y de sus implicaciones para el sector sanitario. El autor expone sus puntos de vista con plena conciencia de su subjetividad y limitaciones.

PI and Fuzzy Control Strategies for High Voltage Output DC-DC Boost Power Converter - Hardware Implementation and Analysis

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...

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...

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.

Light-weight DC to very high voltage DC converter

Science.gov (United States)

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.

The 25 kW resonant dc/dc power converter

Science.gov (United States)

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.

DC grid for home applications

Science.gov (United States)

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.

Static and Dynamic Characteristics of DC-DC Converter Using a Digital Filter

Science.gov (United States)

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.

Calidad de vida urbana: una propuesta para su evaluación

Directory of Open Access Journals (Sweden)

Wilson Giovanni Jiménez Barbosa

2014-08-01

Full Text Available This article presents the methodological basis of the doctoral thesis entitled "Quality of Life in the City of Bogota: An Assessment through the use of the Multidimensional Poverty Index - MPI," an ongoing investigation. Quality of life, understood as people's capability to develop their life projects, depends to a large extent on the guarantee that a nation provides its citizens to accede to a range of primary goods, understood as endowments and rights that a state has agreed to provide for its inhabitants. In recent years, Bogota has developed public policies to ensure this type of primary goods to its residents. The overall objective of the study is to evaluate how these actions have improved the quality of life of citizens; for which MPI was selected. The method was designed by Alkire and Foster and adapted to Colombia by the National Planning Department - DNP. It has been applied to each of the localities that make up the political and administrative divisions of the city. The advantage is it can be broken down into each of its dimensions and indicators, facilitating the formulation and evaluation of policies.

Embolism by silicone - Report of cases and revision of the literature

International Nuclear Information System (INIS)

Paulina Ojeda; Andres Devivero; Adriana Moreno; Monica Sossa

2004-01-01

In Colombia, as in other countries around the world, the current physical beauty concept has increased the number of plastic surgeries, however not everyone has access to these procedures. For those who are less favored culturally and economically, the increasing alternative of an illegal subcutaneous silicone injection, performed by untrained and unscrupulous personnel, with the purpose of changing physically, endangers the patients' life. In this study, 2 cases of pulmonary embolism caused by silicone, which developed respiratory failure and received vital support in Santa Clara Hospital ICU in Bogota, are reviewed. They had a favorable evolution and adequate survival contrary to other reports found in the worldwide literature. The objective is to describe the clinical characteristics and follow-up of the two patients with pulmonary embolism caused by silicone. The clinical records of the two patients who were hospitalized in the ICU of Santa Clara Hospital in Bogota were reviewed and described. Afterwards, the existing literature on Silicone and respiratory failure was reviewed in Pub Med, OVID and HIGHWIRE databases. The illegal application of silicone injections is related to embolism caused by this substance, pulmonary and extra-pulmonary vascular and immunological mechanics impairment and high risk of death

DC-Compensated Current Transformer †

Science.gov (United States)

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

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 ...

Geography of terrosism in Colombia: A retrospective vision

Directory of Open Access Journals (Sweden)

Tania Rodríguez Morales

2017-01-01

Full Text Available The terrorist violence in Colombia was preceded by political violence between Liberals and Conservatives, although we can not argue that the second is responsible for the appearance of the first, however, the accommodation of forces at the beginning of the Cold War took epicenter Latin America and thereby to Colombia. The regions of the country were suddenly pregnant by guerrilla groups praised by the USSR and blood filled the Colombian countryside. Colombian regions saw the birth of the new form of violence that would end up mutating into terrorism. Tolima Colombia-center platform would be the territorial conflict that began engulfing areas and finish an entire country. Only after 2002 it would begin to see the decline of modern terrorism.

Influence of DC arc jets on flow fields analyzed by an integrated numerical model for a DC-RF hybrid plasma

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

Dilation and Curettage (D&C)

Science.gov (United States)

... 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& ...

Ultrahigh-density trench cpacitors in silicon and their application to integrated DC-DC conversion

NARCIS (Netherlands)

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

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...

Programmable dc motor controller

Science.gov (United States)

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.

Hybrid Non-Isolated and Non Inverting Nx Interleaved DC-DC Multilevel Boost Converter for Renewable Energy Applications

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...

A comprehensive analysis and hardware implementation of control strategies for high output voltage DC-DC boost power converter

OpenAIRE

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...

Science and Technology Policy in Colombia: A Comparative Review

NARCIS (Netherlands)

Correa-Restrepo, Juan Santiago; Tejada-Gomez, Maria Alejandra; Cayon-Fallon, Edgardo; Ordonez Matamoros, Hector Gonzalo

2014-01-01

The purpose of the present paper is to assess the current situation of the science and technology system in Colombia from a comparative perspective of quality indicators in Latin America and the Caribbean (LAC). We analyze the development of the science and technology policy in Colombia form a

Apreciación de los profesores acerca de las didácticas que generan aprendizajes significativos en la facultad de psicología de la universidad iberoamericana de Bogotá (Colombia

Directory of Open Access Journals (Sweden)

Jaime Adams Angulo

2011-07-01

Full Text Available Abstract This article presents the results of an investigation whose purpose was to identify the technical and practical knowledge that teachers have about teaching educational implemented at the faculty of psychology at a university in Bogota (Colombia, which generate significant learning in students. It was a descriptive exploratory study and the instrument used was a semi-structured interview that was validated by expert judges rating of 5 and consists of 11 items. The results show that teachers handle teaching focused more on learning of students in the instruction. Besides the main teaching used by teachers include master classes, work guidelines and those that promote active learning such as forums, discussions and seminars and group work. Finally, we highlight the exhibition activities by students who socialize the product of their research and are fed and enriched by the teacher. Resumen Se presentan los resultados de una investigación cuyo propósito fue identificar el conocimiento técnico y práctico que tienen los docentes acerca de las didácticas educativas puestas en práctica en la Facultad de Psicología en una universidad de Bogotá (Colombia, las cuales generan aprendizajes significativos en los estudiantes. Fue un estudio exploratorio de tipo descriptivo y el instrumento utilizado fue una entrevista semiestructurada que se validó mediante la valoración de 5 jueces expertos y consta de 11 ítems. Los resultados muestran que los docentes manejan didácticas enfocadas más en el aprendizaje de los estudiantes que en la instrucción. Además las principales didácticas utilizadas por los docentes son: las clases magistrales, las guías de trabajo y las que promueven el aprendizaje activo como los foros, los debates y los seminarios y el trabajo en grupo. Finalmente, se resaltan las actividades de exposición por parte de los estudiantes, quienes socializan el producto de su investigación y son retroalimentados y enriquecidos

El IDRC en Colombia

International Development Research Centre (IDRC) Digital Library (Canada)

gación de Colombia en salud, agri- ... y desarrollar una base nacional de datos ... apoyada por el IDRC mostró caminos para .... conocimiento con los formuladores de políticas, con otros investigadores y comunidades en todo el mundo.

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.

Actual state and perspectives of the small hydroelectric plants in Colombia

International Nuclear Information System (INIS)

Torres Q, E.; Castillo C, J.J.

1995-01-01

In this article, the actual state of the small-scale hydroelectric power plants (PCHs, abbreviations in Spanish) in Colombia in aspects as: Statistic of the water in Colombia, a brief historical review and the characteristics of the PCHs in Colombia, is present. The development PCHs, the executing projects and the actions that has been develop by the INEA (Institute of Nuclear Sciences and the Alternative Energies) is described

Informational model verification of ZVS Buck quasi-resonant DC-DC converter

Science.gov (United States)

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.

Switched capacitor DC-DC converter with switch conductance modulation and Pesudo-fixed frequency control

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...