Acoustic characterization of magnetic braking with a smartphone

[EN] Smartphone sensors have shown to be adequate to perform physics experiments in high school and first-year university physics courses. The published work covers a wide range of topics within general physics such as linear and circular motions, oscillations, beats, acoustics, and optics, among others. The microphone and speakers have been particularly useful for studying sound phenomena, such as the determination of the speed of sound, the study of acoustic beats, or the Doppler effect.Sepúlveda, CFM.; Castro-Palacio, JC.; Salinas Marín, I.; Monsoriu Serra, JA. (2022). Acoustic characterization of magnetic braking with a smartphone. The Physics Teacher. 60(8):706-707. https://doi.org/10.1119/5.009779270670760

SISTEMA PROTOTIPO PARA LA INCUBACIÓN ARTIFICIAL DE HUEVOS DE AVES MEDIANTE LÓGICA DIFUSA

Este proyecto se hizo con el fin de realizar un primer acercamiento, a la solución de la problemática que se presenta en el departamento del Caquetá, con respecto a la cadena de producción incompleta de la avicultura. Se pretende eliminar la dependencia que tiene el avicultor, al comprar los recién nacidos en lugares alejados al departamento, lo que causa un porcentaje de alta mortalidad. El artículo presenta la implementación de un sistema prototipo para el control de la temperatura y movimiento en el proceso de incubación de huevos de aves mediante lógica difusa. Opcionalmente el sistema puede ser monitoreado por una herramienta software implementada en el lenguaje de programación JAVA en un PC y orientada a la comunicación USB. El diseño de los sistemas de control difuso de temperatura y rotación se desarrollaron mediante la metodología del experto, se implementaron en una plataforma hardware DsPIC y finalmente, se validaron mediante tres enfoques: computacional, de control y de aplicación. Se obtuvo un 85% de eclosión, por lo que se concluye que es viable realizar la incubación artificial con este prototipo de incubadora para huevos de aves

Papel mediador de Cabri en la construcción de rectángulos

En este reporte presentamos trabajos de alumnos de secundaria que participaron en actividades de construcción de paralelogramos, específicamente de rectángulos, los cuales muestran el apoyo que ofrece el uso de software de geometría dinámica (Cabri) para abordar estos problemas de construcción y las estrategias de exploración y en la realización de las construcciones propuestas, al igual que la comunicación de procedimientos y hallazgos

The Smartphone as a Sound Level Meter: Visualizing Acoustical Beats

[EN] Acoustics is a topic in first year Physics courses for engineering students. In this respect, we present in this work a simple experiment to study acoustic beat phenomenon. The superposition of sound waves of slightly different frequencies is captured with the microphone of a smartphone which is placed equidistantly from two speakers which are connected at the same time to AC generators. The smartphone is used here as a measuring instrument. Data registered from the sound level versus time were collected and exported to a «.csv» file for further analysis by means of a free Android application. Based on these data and applying a simple graphing analysis the frequency of the beat was determined and compared with the frequency difference set at the AC generators. Percentage discrepancies within 1% were obtained. This indicates the efficacy of the method used.The authors would like to thank the Institute of Education Sciences of the Universitat Politècnica de València (Spain), for the support to the research groups on teaching innovation MoMa and e-MACAFI and for supporting the Project PIME/2015/B18 which gave rise to this workSalinas Marín, I.; Gimenez Valentin, MH.; Castro-Palacio, J.; Gómez-Tejedor, J.; Monsoriu Serra, JA. (2017). The Smartphone as a Sound Level Meter: Visualizing Acoustical Beats. Tecnica Industrial. 318:34-38. https://doi.org/10.23800/9948S343831

Direct Visualization of Mechanical Beats by Means of an Oscillating Smartphone

[EN] The resonance phenomenon is widely known in physics courses.1 Qualitatively speaking, resonance takes place in a driven oscillating system whenever the frequency approaches the natural frequency, resulting in maximal oscillatory amplitude. Very closely related to resonance is the phenomenon of mechanical beating, which occurs when the driving and natural frequencies of the system are slightly different. The frequency of the beat is just the difference of the natural and driving frequencies. Beats are very familiar in acoustic systems. There are several works in this journal on visualizing the beats in acoustic systems.2¿4 For instance, the microphone and the speaker of two mobile devices were used in previous work2 to analyze the acoustic beats produced by two signals of close frequencies. The formation of beats can also be visualized in mechanical systems, such as a mass-spring system5 or a double-driven string.6 Here, the mechanical beats in a smartphone-spring system are directly visualized in a simple way. The frequency of the beats is measured by means of the acceleration sensor of a smartphone, which hangs from a spring attached to a mechanical driver. This laboratory experiment is suitable for both high school and first-year university physics courses.The authors would like to thank the Institute of Educational Sciences of the Universitat Politecnica de Valencia (Spain) for the support of the Teaching Innovation Groups MoMa and e-MACAFI and for the financial support through the Project PIME 2015 B18.Giménez Valentín, MH.; Salinas Marín, I.; Monsoriu Serra, JA.; Castro-Palacio, JC. (2017). Direct Visualization of Mechanical Beats by Means of an Oscillating Smartphone. The Physics Teacher. 55(7):424-425. https://doi.org/10.1119/1.5003745S42442555

Aplicación de la teoría de opciones a la evaluación del riesgo de crédito en el mercado bursátil español

El Comité de Supervisión Bancaria de Basilea ha publicado recientemente un Nuevo Acuerdo de Capital, conocido como Basilea II, que sustituye al actualmente en vigor, de 1988. Uno de los objetivos del nuevo Acuerdo es la búsqueda de la convergencia entre capital económico y capital regulatorio, permitiendo e incentivando a las entidades financieras a emplear sus propios modelos de medición del riesgo crediticio. En este artículo se analizan los denominados modelos estructurales, cuya inspiración teórica la constituye el modelo de Merton (1974), según el cuál el impago de las obligaciones de una empresa es una variable endógena relacionada con la estructura de capital de la compañía, produciéndose éste en el caso de que el valor de los activos de la firma se sitúe por debajo de un cierto nivel crítico, relacionado con la deuda pendiente de pago.The Basel Committee on Banking Supervision has recently issued a New Capital Accord, commonly known as Basel II, that will replace the current 1988 Accord. The New framework is intended to align regulatory capital requirements more closely with underlying risks, and to provide banks and their supervisors with several options for the assessment of capital adequacy. Banks with more advanced risk management capabilities can make use of an internal ratings-based approach. Under this approach, some of the key elements of credit risk, such as the probability of default of the borrower, will be estimated internally by a bank. In this paper, we focus on the option pricing, or structural approach, as proposed by KMV and which is based on the asset value model originally proposed by Merton (1974). In this model the default process is endogenous, and relates to the capital structure of the firm. Default occurs when the value of the firm’s assets falls below some critical level

Characterization of Berry Aromatic Profile of cv. Trebbiano Romagnolo Grapes and Effects of Intercropping with Salvia officinalis L

Volatile organic compounds (VOCs) are secondary metabolites responsible for the aroma of grapes and the quality of wine. Apart from genetics, agronomic practices may impact the aroma composition and the concentration of volatiles in grape berries. The possible influence of intercropping with medicinal aromatic plants (MAPs) on the VOCs in grape berries’ profile has been poorly explored. Trebbiano Romagnolo is a white Vitis vinifera cultivar cultivated within the Italia region Emilia-Romagna. The study investigated, for the first time, the volatile organic profile of Trebbiano Romagnolo berries as well as the possible influences of intercropping with sage (Salvia officinalis L.) on the volatile composition of grape berries. A total of 48 free and bound aroma compounds were identified using solid phase extraction-gas chromatography-mass spectrometry (SPE-GC-MS). In the free aroma fraction, the main classes were C6 derivatives, alcohols, and benzenes, while in the bound aroma fraction, the major classes were benzenes, C13 norisoprenoids, and terpenes. The results obtained in this experiment indicate that intercropping with Salvia officinalis may influence volatile compounds in grape berries, an interesting result in cultivars considered neutral such as Trebbiano Romagnolo, providing new insights for exploring the complexity of the terroir and the role of agroecological strategies

El Análisis Didáctico. Una posibilidad de Transformar las Prácticas en Física: El caso del Movimiento

The focal point is the design of teaching units for the Kinematics and Dynamics, and the Problem of Movement courses: a proposal for training teachers pursuing a bachelor’s degree in Physics and Mathematics. This proposal is part of the research project “Pedagogical Analysis: a possibility for curricular integration in the formation of teachers of Mathematics and Physics”.  It is proposed for freshmen, having the Second Law of Newton as core content.  In the development of these units, the study and analysis of the Second Law of Newton is set as the main task, considering the four approaches of pedagogical analysis. During its implementation, students displayed a favorable attitude towards the tasks, and there was evidence of higher levels of conceptualization, which in turn allowed participant teachers to reflect on the mastering level that they have of the topics to be covered, along with their teaching approaches.Se plantean como objeto central el Diseño de Unidades Didácticas para los Programas de Curso Cinemática y Dinámica y el Problema del Movimiento: Una propuesta para formación de profesores en la Licenciatura Matemáticas y Física, como parte del proyecto de investigación “El análisis didáctico: Una posibilidad de integración curricular en la formación de profesores de matemáticas y física”. Tomando como foco de contenido, la Segunda Ley de Newton.  En el desarrollo de la unidad didáctica se plantea como objetivo el estudio y análisis de la segunda Ley de Newton a partir del análisis didáctico en sus cuatro componentes. En su aplicación se encontró una actitud favorable del estudiante frente al desarrollo de las tareas, se evidencia procesos de conceptualización a mayor nivel, y permitió al docente reflexionar sobre el nivel de apropiación que posee de las temáticas que va a trabajar, como también del manejo didáctico y pedagógico