1,176 research outputs found
Growth, characterization and applications of metal oxides on graphitic systems
Tesis Doctoral ineÌdita leiÌda en la Universidad AutoÌnoma de Madrid, Facultad de Ciencias, Departamento de FiÌsica Aplicada. Fecha de lectura: 03-10-201
PWM Control of a Buck Converter with an Amorphous Core Coil
Pulse-width modulation is widely used to control electronic converters. One of the most topologies used for high DC voltage/low DC voltage conversion is the Buck converter. It is obtained as a second order system with a LC filter between the switching subsystem and the load. The use of a coil with an amorphous magnetic material core instead of air core lets design converters with smaller size. If high switching frequencies are used for obtaining high quality voltage output, the value of the auto inductance L is reduced throughout the time. Then, robust controllers are needed if the accuracy of the converter response must not be affected by auto inductance and load variations. This paper presents a robust controller for a Buck converter based on a state space feedback control system combined with an additional virtual space variable which minimizes the effects of the inductance and load variations when a not-toohigh switching frequency is applied. The system exhibits a null steady-state average error response for the entire range of parameter variations. Simulation results are presented
Using the Own Flexibility of a Climbing Robot as a Double Force Sensor
Force sensors are used when interaction tasks are carried out by robots in general, and by climbing robots in particular. If the mechanics and electronics systems are contained inside the own robot, the robot becomes portable without external control. Commercial force sensors cannot be used due to limited space and weight. By selecting the links material with appropriate stiffness and placing strain gauges on the structure, the own robot flexibility can be used such as force sensor. Thus, forces applied on the robot tip can be measured without additional external devices. Only gauges and small internal electronic converters are necessary. This paper illustrates the proposed algorithm to achieve these measurements. Additionally, experimental results are presented
The reproducibility crisis in science from the perspective of thin film deposition: an unexpected approach
The publication of scientific results in all disciplines, and in particular in Material Science, has geometrically increased in the last decades.
Although the quality of the published results seems to follow the same trend, the feeling that we could be facing a reproducibility crisis has become
extended within the scientific community. We discuss this issue in relation to thin film deposition techniques such as atomic layer deposition, which
should not present deviations on the reported results due to its self-limiting nature. In particular, we put the focus on the necessity of a multipolar
approach that takes into account also the global environment in which researchers perform their wor
Are you ready for retirement? The influence of values on membership in voluntary organizations in midlife and old age
Membership in voluntary organizations is associated with individual and
social benefits. Due to the negative consequences of the global pandemic
on older people, and the governmental challenges posed by population
aging, voluntary membership is of great importance to society. To
effectively promote volunteering among older people, it is necessary to
understand the determinants of voluntary membership. This study analyses
the influence of individual valuesâsecular/traditional and survival/selfexpressionâ
on voluntary membership among European adults (N = 31,985).
Specifically, it examines which values orient two age groups (middle age:
50â64 and old age: 65â79), as well as men and women toward a
certain type of association (Social Awareness; Professional and Political;
Education and Leisure; Religion). The sample of 31,985 comprises 60%
of adults aged 50â64 and 40% aged 65â79; of which 56% are women
and 44% men. The empirical estimation considers different levels of data
aggregation: individual, national and welfare system, therefore multilevel
analysis is used as an analytical strategy. Individual-level variables from the
Integrated Values Survey (2005/09, 2010/14, and 2017/20) and nationallevel
variables (Gini Index and Gross Domestic Product Per Capita)
from the World Bank and Eurostat are used. The results indicate that
traditional and self-expression values promote membership in voluntary
organizations in general more than secular and survival values. However,
there are differences according to the type of organization. Furthermore,
values are found to moderate the effect of age and gender on
voluntary membership.Gobierno de Aragon CSO2017-82110-RSpanish Government PRE2018-083981State Research Agency
BYCS S16_17
USJ Herbarium of Costa Rica: history and contributions
En 2011 el Herbario USJ de Costa Rica cumpliĂł 80 años y llegĂł a 100 000 especĂmenes de todos los taxa que estudia la botĂĄnica. Se anotan datos y cifras sobre historia, fundadores y contribuciones de USJ al conocimiento florĂstico de Costa Rica.In 2011 the Herbarium USJ of the University of Costa Rica became 80 years old and came up with 100 000 specimens of all the taxa that traditional botany studies. Data and figures on the history, the founders, and contributions of USJ to the knowledge of Costa Rican flora are summarized.UCR::VicerrectorĂa de Docencia::Ciencias BĂĄsicas::Facultad de Ciencias::Escuela de BiologĂ
Sobre un opus magnum de la orquideologĂa neotropical: HĂĄgsater, E. & L. SĂĄnchez Saldaña (Eds.). (2004). Icones Orchidacearum, Fasc. 7, The genus Epidendrum, part 4. âA fourth century of new species in Epidendrumâ
Se analiza brevemente la obra referida y se compara con otras de su mismo tipo. Se incluyen reflexiones sobre el uso del latĂn y del griego en botĂĄnica, asĂ como sobre el futuro de la orquideologĂa neotropical.UCR::VicerrectorĂa de Docencia::Ciencias BĂĄsicas::Facultad de Ciencias::Escuela de BiologĂ
The flowering of Australiaâs Rainforests; a plant and pollination miscellany
Se comenta y describe el libro "The flowering of Australiaâs Rainforests; a plant and pollination miscellany" (2010), principalmente sobre la ecologĂa de la polinizaciĂłn en los bosques lluviosos australianos.UCR::VicerrectorĂa de Docencia::Ciencias BĂĄsicas::Facultad de Ciencias::Escuela de BiologĂ
En busca de Karl Hoffmann
Se comenta y analiza el libro biogrĂĄfico escrito por Luko Hilje "Karl Hoffmann: naturalista, mĂ©dico y hĂ©roe nacional" (Heredia, Costa Rica: INBio, 2006).UCR::VicerrectorĂa de Docencia::Ciencias BĂĄsicas::Facultad de Ciencias::Escuela de BiologĂ
Marketing de influencers y nuevas estrategias digitales
ESTE ESTUDIO SE DESARROLLA CON EL OBJETIVO DE ANALIZAR CĂMO SE HA ADAPTADO EL MARKETING AL NUEVO ESTILO DE VIDA DE LA SOCIEDAD PROVOCADO POR LOS AVANCES TECNOLĂGICOS. MAS CONCRETAMENTE, CĂMO EL MARKETING SE HA INTRODUCIDO EN LAS REDES SOCIALES Y LA MANERA QUE TIENE DE LLEGAR AL PĂBLICO POR MEDIO DE UNA FIGURA TAN REPRESENTATIVA DE ELLAS COMO ES LA DEL INFLUENCER.
EL PROPĂSITO DE ESTE ESTUDIO HA SIDO EL DE DESCUBRIR QUĂ ES EL MARKETING DE INFLUENCERS Y LA INFLUENCIA QUE ESTOS TIENEN EN LOS COMPRADORES, POR QUĂ LAS EMPRESAS INVIERTEN CADA VEZ MĂS EN ESTE TIPO DE CAMPAĂAS PUBLICITARIAS Y CĂMO HAN CAMBIADO SUS ESTRATEGIAS A LA HORA DE ELEGIR Y COLABORAR CON UN PERSONAJE PĂBLICO EN LOS ĂLTIMOS AĂOS, ASĂ COMO EN QUĂ ASPECTOS SE BASAN EN EL MOMENTO EN EL QUE VAN A INTRODUCIRSE EN EL MUNDO DEL MARKETING DE INFLUENCERS Y QUĂ PROCESO HAY QUE LLEVAR A CABO A LA HORA DE INICIAR UNA CAMPAĂA PUBLICITARIA POR MEDIO DE LAS REDES SOCIALES.
POR ĂLTIMO, ANALIZAR LAS ESTRATEGIAS LLEVADAS A CABO POR LAS EMPRESAS PARA INTRODUCIRSE EN EL MUNDO DE LAS REDES SOCIALES DENOMINADO MARKETING SOCIAL MEDIA.
EN CUANTO A LAS PRINCIPALES CONCLUSIONES, SE PUEDE AFIRMAR QUE EL CRECIMIENTO DE LA INVERSIĂN EN MARKETING DE INFLUENCERS CONTINUARĂ EN EL FUTURO. LAS REDES SOCIALES Y ESTOS PERSONAJES PĂBLICOS HAN ADQUIRIDO TANTA REPERCUSIĂN QUE SON CAPACES DE MOVILIZAR A MILLONES DE PERSONAS. TRANSMITEN CERCANĂA Y CONFIANZA A SU COMUNIDAD, POR LO QUE TIENEN LA CAPACIDAD DE HUMANIZAR A LAS MARCAS. PERO NO TODOS LOS INFLUENCERS PUEDEN REPRESENTAR A CUALQUIER MARCA, TIENEN QUE EXISTIR CIERTAS SIMILITUDES ENTRE ELLOS, HECHO QUE HARĂ QUE LA COMUNIDAD SE IDENTIFIQUE CON LA MARCA.
EN CUANTO AL MARKETING SOCIAL MEDIA, EL DESCONOCIMIENTO POR PARTE DE LAS EMPRESAS EN ESTA VERTIENTE HACE QUE CADA VEZ ESTAS ESTRATEGIAS SEAN MĂS UTILIZADAS. PODEMOS CONCLUIR QUE, ANALIZANDO LAS CAMPAĂAS EXITOSAS DE SOCIAL MEDIA QUE HEMOS ESTUDIADO, UNA ESTRATEGIA DE ESTE TIPO PUEDE AYUDAR A UNA EMPRESA A AUMENTAR SU VISIBILIDAD, PERO AL FINAL, LA AUDIENCIA MANDA. NO POR INVERTIR MĂS DINERO O HACER UN ANĂLISIS MĂS EXHAUSTIVO DEL ENTORNO VAMOS A CONECTAR CON LA GENTE EN LAS REDES SOCIALES, PERO NOS PUEDE DAR LAS PAUTAS PARA INICIAR UN CAMINO EN EL MUNDO DIGITAL QUE PUEDE ACABAR DĂNDONOS BUENOS RESULTADOS
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