Omnidirectional photonic band gaps in one-dimensional gradient refractive index photonic crystals considering linear and quadratic profiles

Calvo-Velasco D.M.,Sánchez-Cano Robert 한국물리학회 2022 Current Applied Physics Vol.35 No.-

By using the transfer matrix formalism, in this work it is presented the study of the optical properties of 1D photonic structures constructed with M periods of bilayers of dielectric material and slabs with gradient refractive index (GRIN) profile of two types: linear and quadratic. By varying the profile parameters, preserving the average value of the refractive index for the GRIN slab, the results show the formation of new photonic band gaps whose bandwidths depends on the slope and the curvature of the linear and quadratic profile respectively. Also, it can be observed the formation of omnidirectional photonic bandgaps for the TE and TM polarizations, one for the linear profile and three for the quadratic one, for which their bandwidths depend linearly on the slope and the curvature of the GRIN profiles. It is expected that the presented results could be useful in the construction of optical devices based in their optical response under oblique incidence.

Theoretical study of 1D gradient photonic structures with quartic polynomial dielectric profile formed by AllGa1-lAs varying pressure and temperature under oblique incidence

Calvo-Velasco D.M.,Sánchez-Cano Robert 한국물리학회 2022 Current Applied Physics Vol.41 No.-

In this work it is presented a theoretical study of the optical properties of 1D photonic systems with gradient dielectric profile layers of quartic polynomial type, using the dielectric AllGa1-lAs being the Al concentration along the width of the slab as the gradient function, when external parameters as the pressure and the temperature are considered. It is shown that the proposed gradient profile admits an analytic approach supported on the method of series to find the solutions of the wave equations for the TE and TM polarizations. Also, it is proposed a new regression model for the calculation of the dielectric value of AllGa1-lAs as a function of the pressure and temperature. The results showed that the increase in the pressure shifts and changes the transmission bands due to the decrease in the dielectric mean value of the gradient slab. On the other hand, it is found that the increase in the temperature shifts the transmission bands to lower frequencies but without changing their shape distribution. Considering the inclusion of graphene, it is observed its effect on the distribution of the transmission bands at different frequencies depending on the graphene properties. It is expected that the proposed structure can be contribute to the development of new devices when the pressure, the temperature and the chemical potential of graphene are used as external tunable parameters.

Vectorial Method of Minimum Zone Tolerance for Flatness, Straightness, and their Uncertainty Estimation

Roque Calvo,Emilio Gómez,Rosario Domingo 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.

Flatness and planar straightness are fundamental form tolerances in engineering design and its materialization through manufacturing processes. Minimum zone tolerance is a preferred approach of flatness and straightness for widely accepted ISO and ANSI standards. In this paper, we propose a novel accurate method of minimum zone tolerance based on vectorial calculus of point coordinates. The non-linear minimax formulation of the original flatness or straightness problem is transformed into a set of linear problems. Next, the optimal solution of the envelop planes or lines is reached through vectorial calculus for both flatness and planar straightness. Then, the developed algorithms are compared to a selection of methods with published tests in recent and classic literature on the topic, reaching the best attained accuracies or outperforming them in the trials. Finally, we propose a new decomposition of the uncertainty contributions for analysis and the improvement of sampling strategy. We conclude remarking the practical contributions of the proposals.

Evaluating the quality of the service offered by a bus rapid transit system: the case of Transmetro BRT system in Barranquilla, Colombia

Erick Calvo,Mario Ferrer 서울시립대학교 도시과학연구원 2018 도시과학국제저널 Vol.22 No.3

The purpose of this research is to evaluate the quality of service offered by the BRT (Bus Rapid Transit) System in the City of Barranquilla, Colombia. A model is designed and tested to explore critical quality factors that stakeholders consider important to predict passenger satisfaction with the service. The study aims at identifying the quality factors that could help to improving the existing transportation service-related research in emerging economies such as Colombia (a country where the growth of the mass transportation sector is expected following significant investments made by the government). This research shows that the four independent variables – information availability, safety on buses, ergonomics, and system accessibility have a positive and significant predictive power of the quality of the service.

Learning Systems : Systems that learn & support learning

Rafael A. Calvo 한국멀티미디어학회 2008 한국멀티미디어학회 국제학술대회 Vol.2008 No.-

Polyurea membrane for water cleaning: Kinetic and equilibrium modeling of dyes adsorption

del Campo Calvo Pablo,de Oliveira Lilian Karla,de Oliveira Nicole Aparecida Amorim,Molina Eduardo Ferreira 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.12

The present treatment of water from aqueous solutions, reported from our research work, uses polyurea (PU) as a novel adsorbent. Specifically, the adsorption efficacy of PU was tested in dyes with different characteristics (Congo red (CR) and methylene blue (MB)). The PU membrane was obtained by a sol-gel chemistry reaction of polyetheramine with polyisocyanate resulting in the formation of urea groups, confirmed through FTIR analysis. The polymeric membrane exhibited a high homogeneity, making it a viable purifying technology for wastewater. The high swelling capacity of the membrane played a crucial role in the CR dye diffusion/adsorption. Notably, PU membranes showed excellent adsorption to CR anionic dye, resulting in a removal efficiency over 85%. However, MB dye adsorption was less favorable, suggesting a high affinity with anionic species. Our analysis revealed that the adsorption of CR dye onto PU membranes follows the pseudo-second order kinetic and Langmuir isotherm models. Moreover, the intra-particle diffusion model demonstrated that the swelling of PU facilitates the adsorption/diffusion process, thereby accelerating the mass transfer of the CR dye onto the membrane. Overall, our findings suggest that PU membranes derived from commercially available reagents are highly promising for the decontamination of dye wastewater.

INFLUENCE OF SHOCK ABSORBER WEARING ON VEHICLE BRAKE PERFORMANCE

Jose A. Calvo,José L. San Roman,Daniel García-Pozuelo 한국자동차공학회 2008 International journal of automotive technology Vol.9 No.4

In order to safely maintain a vehicle, it is necessary to verify the most important systems that affect safety during Periodic Motor Vehicle Inspections (PMVIs). In a previous paper, a test method and validation criteria were suggested by the authors to verify shock absorber status during PMVIs, as they are a fundamental component that may wear out during a vehicle's life. In this paper, variations of the performance of the vehicle's brakes resulting from shock absorber wearing have been analyzed, in order to confirm whether the suggested criteria is valid for taking into account longitudinal forces and pitch movement on the vehicle. A simulation-based study was conducted with several configurations of a worn damper on a vehicle driving on two virtual roads: smooth and undulating. The results confirmed that the damping coefficient established as an acceptable value to verify the shock absorber status in PMVIs is also valid considering the forces involved in a braking maneuver.

La antiguedad clasica como fuente y contexto en El esclavo en grillos de oro de Bances Candamo

( Ignacio Lopez Calvo ) 한국스페인어문학회 2006 스페인어문학 Vol.0 No.41

La antiguedad clasica sirve de trasfondo a la comedia El esclavo en grillos de oro en donde el dramaturgo aurisecular Francisco Bances Candamo(1662-1704)refleja sus inquietudes politicas. Con la presentacion de los enredos politicos del imperio romano, el dramaturgo asturiano consigue que el lector-espectador tome conciencia de la sombra amenazadora que acosa a la monarquia de Carlos II el Hechizado (1661-1700), dada la ausencia de heredero. La critica ha mencionado varios tratados destinados a la educacion de principes. Sin embargo, no se ha mencionado nunca un texto que parece haber tenido tambien mucha influencia en su obra: la Oracion a Nicocles, rey de Chipre, de Isocrates. En El esclavo en grillos de oro, ademas del esperado panegirico al rey, encontramos una osadia que acabaria costando muy cara a su autor. Como Isocrates, Bances Candamo tratade educar al rey para el buen gobierno e incluso se atreve a volver a mencionar el tema tabu de la sucesion. Al instar indirectamente al rey a que buscara un heredero para Espana, y al criticar a los allegados al emperador romano, la corte lo considero una afrenta tanto al rey como al privado de Carlos II. De hecho, tras ser herido en el pecho por un espectador que vio en El esclavo en grillos de oro un ataque al Conde de Oropesa, privado del rey, Bances Candamo se vio obligado, como se menciono anteriormente, a dejar su cargo y huir de Madrid por un tiempo.

Comorbidity Between Anorexia Nervosa and Depressive Disorder: A Narrative Review

Maria Pilar Calvo-Rivera,Maria Isabel Navarrete-Páez,Isabel Bodoano,Luis Gutiérrez-Rojas 대한신경정신의학회 2022 PSYCHIATRY INVESTIGATION Vol.19 No.3

Objective Anorexia nervosa (AN) is a disorder with a significantly high prevalence. Affective disorders, including depressive disorder (DD), often coexist with this eating disorder (ED). In this review we will focus on its prevalence, associated vulnerability factors, clinical manifestations, possible etiological factors and its prognosis.Methods A bibliographic search was carried out in the PubMed database selecting those articles that approached the subject of comorbidity between AN and DD. The search was limited to articles published from January 1990 to December 2021.Results Of the 1891 abstracts reviewed, 33 studies met inclusion criteria. The prevalence of this comorbidity was extremely variable between studies, which exposed their heterogeneity. As to symptomatology this comorbidity presents itself with more severity, greater expression of psychological traits and greater cognitive impairment. Certain personality traits are postulated as vulnerability factors. Genetic factors such as neurochemicals seem to be involved in its pathogenesis.Conclusion The comorbidity between DD and ED have important influence in its symptomatic expression, severity and prognosis. Some of the analyzed studies provide consistent data, but there are others that are contradictory. It would be necessary to increase the number of studies and use a unified methodology.

La antig?edad cl?sica como fuente y contexto en El esclavo en grillos de oro de Bances Candamo

Ignacio L?pez-Calvo 한국스페인어문학회 2006 스페인어문학 Vol.0 No.41

La antigüedad clásica sirve de trasfondo a la comedia El esclavo en grillos de oro en donde el dramaturgo aurisecular Francisco Bances Candamo(1662-1704)refleja sus inquietudes políticas. Con la presentación de los enredos políticos del imperio romano, el dramaturgo asturiano consigue que el lector-espectador tome conciencia de la sombra amenazadora que acosa a la monarquía de Carlos II el Hechizado (1661-1700), dada la ausencia de heredero. La crítica ha mencionado varios tratados destinados a la educación de príncipes. Sin embargo, no se ha mencionado nunca un texto que parece haber tenido también mucha influencia en su obra: la "Oración" a Nicocles, rey de Chipre, de Isócrates. En El esclavo en grillos de oro, además del esperado panegírico al rey, encontramos una osadía que acabaría costando muy cara a su autor. Como Isócrates, Bances Candamo tratade educar al rey para el buen gobierno e incluso se atreve a volver a mencionar el tema tabú de la sucesión. Al instar indirectamente al rey a que buscara un heredero para España, y al criticar a los allegados al emperador romano, la corte lo consideró una afrenta tanto al rey como al privado de Carlos II. De hecho, tras ser herido en el pecho por un espectador que vio en El esclavo en grillos de oro un ataque al Conde de Oropesa, privado del rey, Bances Candamo se vio obligado, como se mencionó anteriormente, a dejar su cargo y huir de Madrid por un tiempo.