Didáctica de la Física Experimental con Smartphones

Tesis por compendio[ES] El objetivo fundamental de esta Tesis es explorar nuevas vías de aplicación de los sensores de los smartphones a la didáctica de la Física. Al mismo tiempo que se introduce un elemento innovador, como es el uso de un dispositivo móvil como herramienta de medida, se ha optado por ensayos sencillos que se puedan adaptar tanto a las enseñanzas a nivel de educación secundaria como universitaria. En este documento se recopila, en formato de compendio de publicaciones, una serie de experiencias que aportan una perspectiva diferente al trabajo realizado en un laboratorio. Se utiliza el sensor de aceleración para el estudio del movimiento rectilíneo vibratorio forzado con amortiguamiento débil, en un carril cinemático, y del movimiento oscilatorio armónico, en un aparato de torsión; el sensor de presión para el análisis de las oscilaciones amortiguadas en un medio viscoso; el giroscopio para estudiar la dinámica de un yoyó; y, finalmente, el sensor de luz ambiente para el análisis de la dependencia de la iluminancia con la distancia.[CA] L'objectiu fonamental d'aquesta Tesi és explorar noves vies d'aplicació dels sensors dels smartphones a la didàctica de la Física. Al mateix temps que s'introdueix un element innovador, com és l'ús d'un dispositiu mòbil com a eina de mesura, s'ha optat per assajos senzills que es puguen adaptar tant als ensenyaments a nivell d'educació secundària com a universitària. En aquest document es recopila, en format de compendi de publicacions, una sèrie d'experiències que aporten una perspectiva diferent al treball realitzat en un laboratori. S'utilitza el sensor d'acceleració per a l'estudi del moviment rectilini vibratori forçat amb esmorteïment dèbil, en un carril cinemàtic, i del moviment oscil·latori harmònic en un aparell de torsió; el sensor de pressió per a l'anàlisi de les oscil·lacions esmorteïdes en un mitjà viscós; el giroscopi per a estudiar la dinàmica d'un io-io; i, finalment, el sensor de llum ambient per a l'anàlisi de la dependència de la il·luminancia amb la distància.[EN] The main objective of this Thesis aims to explore new ways of applying the sensors of smartphones to the didactics of Physics. At the same time that an innovative element is introduced, such as the use of a mobile device as a measuring tool, simple experiments have been chosen to being adapted to both secondary and university education. This document compiles a series of publications that show a different approach to the laboratory work. The acceleration sensor enables us to study the forced and damped oscillations in a dynamic track, and the harmonic oscillatory motion, in a torsion apparatus; the pressure sensor is used for the analysis of damped oscillations in a viscous medium; the gyroscope to study the dynamics of a yo-yo; and, finally, the ambient light sensor is used to determine the dependence of the illuminance of several light sources with the distance.Salinas Marín, I. (2019). Didáctica de la Física Experimental con Smartphones [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/125698TESISCompendi

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

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

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

Design and evaluation of a three-dimensional virtual laboratory on vector operations

[EN] In Physics, many quantities are vectors, and their use requires typical operations such as addition, subtraction, scalar multiplication, scalar product (dot product), vector product (cross product), and scalar triple product. This is a very basic topic in all General Physics courses for Engineering degrees. However, we have detected that some students lack a deep understanding of vector operations and their properties. In this study, we present a virtual laboratory (developed using the tool Easy Java Simulations) for the study and understanding of these topics. The user can introduce the components of the input vectors and gets a three-dimensional representation, which can be scaled and rotated for better visualization. Any of the aforementioned operations can be selected, and the result is shown both numerically and graphically. The user can also modify any represented vector. In this way, the virtual lab provides a real-time visualization of how the change affects the result. The possibility of limiting the changes to either magnitude or direction is also included. The efficiency of the virtual laboratory has been tested analyzing the results obtained in two groups of students (virtual laboratory vs traditional resources). A satisfaction survey has been also carried out.Universitat Politecnica de Valencia, Grant/Award Number: PIME B24Salinas Marín, I.; Gimenez Valentin, MH.; Cuenca Gotor, VP.; Seiz Ortiz, R.; Monsoriu Serra, JA. (2019). Design and evaluation of a three-dimensional virtual laboratory on vector operations. Computer Applications in Engineering Education. 27(3):690-697. https://doi.org/10.1002/cae.22108S690697273Vidaurre, A., Riera, J., Giménez, M. H., & Monsoriu, J. A. (2002). Contribution of digital simulation in visualizing physics processes. Computer Applications in Engineering Education, 10(1), 45-49. doi:10.1002/cae.10016Depcik, C., & Assanis, D. N. (2005). Graphical user interfaces in an engineering educational environment. Computer Applications in Engineering Education, 13(1), 48-59. doi:10.1002/cae.20029Jimoyiannis, A., & Komis, V. (2001). Computer simulations in physics teaching and learning: a case study on students’ understanding of trajectory motion. Computers & Education, 36(2), 183-204. doi:10.1016/s0360-1315(00)00059-2Esquembre, F. (2002). Computers in physics education. Computer Physics Communications, 147(1-2), 13-18. doi:10.1016/s0010-4655(02)00197-2Steinberg, R. N. (2000). Computers in teaching science: To simulate or not to simulate? American Journal of Physics, 68(S1), S37-S41. doi:10.1119/1.19517GiménezMH SalinasI andMonsoriuJA Visualizador de operaciones con vectores (español/valencià/english) 2017.http://hdl.handle.net/10251/84650Accessed February 1 2019.TiplerPAandMoscaG Physics for Scientists and Engineers. New York NY: W.H. Freeman Cop 2008.NaveR HyperPhysics 2016.http://hyperphysics.phy‐astr.gsu.edu/hbase/hph.htmlAccessed February 1 2019.Esquembre, F. (2004). Easy Java Simulations: a software tool to create scientific simulations in Java. Computer Physics Communications, 156(2), 199-204. doi:10.1016/s0010-4655(03)00440-5Complements of Physics course description (2017).http://www.upv.es/titulaciones/GIM/menu_1015238i.htmlAccessed February 1 2019.Basic Physics for Engineering course description (2017).http://www.upv.es/titulaciones/GIEL/menu_1014686i.htmlAccessed February 1 2019

La simulación digital como apoyo para la visualización de procesos ondulatorios

Una de las líneas que venimos desarrollando en la enseñanza de la Física en la E.U.I.T.I. de la Universidad Politécnica de Valencia, es la de la simulación digital, utilizando animaciones, de procesos físicos relativamente complejos, tales como los ondulatorios. En esta comunicación se muestran mediante el programa ONDAS las posibilidades de este tipo de simulación para explicar conceptos tales como: ondas longitudinales, transversales y mixtas; ondas electromagnéticas; ondas estacionarias; dispersión; absorción; ...One of the guidelines that we are developing in Physics Education in the E.U.I.T.I. in the Universidad Politécnica de Valencia, is digital simulation, by animations, of relatively complex physical processes, such as wave processes. In this presentation, the program ONDAS shows the possibilities of digital simulation for explaining concepts such as: longitudinal, transverse and mixed waves; electromagnetic waves; standing waves; dispersion; absorption; ..

Características de la población ocupada en Colombia : un análisis del perfil de los formales e informales

RESUMEN: En este trabajo se examinan las características de la población ocupada en Colombia y la recompensa del mercado a cambios en estas, distinguiendo entre trabajadores formales e informales a partir de los enfoques (OIT y Legalidad). Esta caracterización se realiza estimando modelos tipo probit para obtener los perfiles de la población económicamente activa (ocupados, desocupados y desempleados), y posteriormente se analizan las características que afectan los ingresos de los ocupados (formales e informales) haciendo uso de funciones de ingreso Mincerianas con corrección de sesgo de selección. Los ejercicios econométricos se realizan para los años 2001, 2003 y 2006. En los principales resultados se observa que las mujeres y los trabajadores por cuenta propia son primordialmente, quienes conforman el sector informal. Los ingresos de los ocupados formales son más sensibles a incrementos en los niveles educativos y los de los informales a incrementos en la experiencia; efectos marginales que son más notorios para los asalariados.ABSTARCT: This work analyses the main characteristics of occupied population in Colombia and how the labor market rewards changes in worker’s profile. We emphasize on differences between formal and informal workers based on two definitions of the informal sector: ILO and legalist. First, we estimate Probit models to characterize the main statuses of the economically active population (workers, unemployed and inactive population), and distinguish between formal and informal workers. Second, we analyze how the workers’ profile affects their labor income through Mincer equations with correction for self-selection bias. These equations were estimated for years 2001, 2003 and 2006. We found that the informal sector is mainly composed of women and self-employed workers. The labor income of formal workers is more sensible to changes in educational level, whereas the labor income of informal workers is more sensible to changes in experience. Marginal effects are more evident for salaried workers than for the self-employed

UCO physical rehabilitation: new dataset and study of human pose estimation methods on physical rehabilitation exercises

Physical rehabilitation plays a crucial role in restoring motor function following injuries or surgeries. However, the challenge of overcrowded waiting lists often hampers doctors’ ability to monitor patients’ recovery progress in person. Deep Learning methods offer a solution by enabling doctors to optimize their time with each patient and distinguish between those requiring specific attention and those making positive progress. Doctors use the flexion angle of limbs as a cue to assess a patient’s mobility level during rehabilitation. From a Computer Vision perspective, this task can be framed as automatically estimating the pose of the target body limbs in an image. The objectives of this study can be summarized as follows: (i) evaluating and comparing multiple pose estimation methods; (ii) analyzing how the subject’s position and camera viewpoint impact the estimation; and (iii) determining whether 3D estimation methods are necessary or if 2D estimation suffices for this purpose. To conduct this technical study, and due to the limited availability of public datasets related to physical rehabilitation exercises, we introduced a new dataset featuring 27 individuals performing eight diverse physical rehabilitation exercises focusing on various limbs and body positions. Each exercise was recorded using five RGB cameras capturing different viewpoints of the person. An infrared tracking system named OptiTrack was utilized to establish the ground truth positions of the joints in the limbs under study. The results, supported by statistical tests, show that not all state-of-the-art pose estimators perform equally in the presented situations (e.g., patient lying on the stretcher vs. standing). Statistical differences exist between camera viewpoints, with the frontal view being the most convenient. Additionally, the study concludes that 2D pose estimators are adequate for estimating joint angles given the selected camera viewpoints

Characterization of linear light sources with the smartphone's ambient light sensor

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.Salinas Marín, I.; Gimenez Valentin, MH.; Monsoriu Serra, JA.; Castro-Palacio, J. (2018). Characterization of linear light sources with the smartphone's ambient light sensor. The Physics Teacher. 56(8):562-563. https://doi.org/10.1119/1.5064575S56256356

A computer-assisted experiment to study the influence of the Point Spread Function in the image formation process

[EN] We present a new open experimental setup assisted with LabView to be used to teach the concept of the point spread function (PSF). The PSF describes the response of an image-forming system to a point object. The PSF concept is of fundamental importance in optics since the output of an image-forming system can be simulated as the convolution of the PSF with the input object. In this work, a new graphical user interface has been developed to obtain a real-time measure of the PSF and the corresponding images provided by different lenses and pupils with different sizes and shapes. From a didactical point of view, the proposed method allows students to interpret the results in a visual and heuristic way.This study was supported by the Ministerio de Economia y Competitividad and FEDER (Grant DPI 2015-71256-R) and by Generalitat Valenciana (Grant PROMETEOII/2014/072), Spain.Ferrando Martín, V.; Remón Martín, L.; Salinas Marín, I.; Monsoriu Serra, JA.; Furlan, WD. (2018). A computer-assisted experiment to study the influence of the Point Spread Function in the image formation process. European Journal of Physics. 39(6):1-13. https://doi.org/10.1088/1361-6404/aadce0S11339