En este trabajo se presenta una comparación de los tiempos de respuesta, optimización de la ruta y complejidad del grafo en métodos de planificación de trayectoria para robots móviles autónomos. Se contrastan los desarrollos de Voronoi, Campos potenciales, Roadmap probabilístico y Descomposición en celdas para la navegación en un mismo entorno y validándolos para un número variable de obstáculos. Las evaluaciones demuestran que el método de generación de trayectoria por Campos Potenciales, mejora la navegación respecto de la menor ruta obtenida, (...) el método Rapidly Random Tree genera los grafos de menor complejidad y el método Descomposición en celdas, se desempeña con menor tiempo de respuesta y menor coste computacional. Palabras Clave: optimización, trayectoria, métodos de planificación, robots móviles. Referencias [1]H. Ajeil, K. Ibraheem, A. Sahib y J. Humaidi, “Multi-objective path planning of an autonomous mobile robot using hybrid PSO-MFB optimization algorithm, ” Applied Soft Computing, vol. 89, April 2020. [2]K.Patle, G. Babu, A. Pandey, D.R.K. Parhi y A. Jagadeesh, “A review: On path planning strategies for navigation of mobile robot,” Defence Technology, vol. 15, pp. 582-606, August 2019. [3]T. Mack, C. Copot, D. Trung y R. De Keyser, “Heuristic approaches in robot path planning: A survey,” Robotics and Autonomous Systems, vol. 86, pp. 13-28, December 2016. [4]L. Zhang, Z. Lin, J. Wang y B. He, “Rapidly-exploring Random Trees multi-robot map exploration under optimization framework,” Robotics and Autonomous Systems, vol. 131, 2020. [5]S. Khan y M. K. Ahmmed, "Where am I? Autonomous navigation system of a mobile robot in an unknown environment," 2016 5th International Conference on Informatics, Electronics and Vision, pp. 56-61, December 2016. [6]V. Castro, J. P. Neira, C. L. Rueda, J. C. Villamizar y L. Angel, "Autonomous Navigation Strategies for Mobile Robots using a Probabilistic Neural Network," IECON 2007 - 33rd Annual Conference of the IEEE Industrial Electronics Society, pp. 2795-2800, Taipei, 2007. [7]Y. Li, W. Wei, Y. Gao, D. Wang y C. Fan, “PQ-RRT*: An improved path planning algorithm for mobile robots,” Expert Systems with Applications, vol. 152, August 2020. [8]A. Muñoz, “Generación global de trayectorias para robots móviles, basada en curvas betaspline,” Dep. Ingeniería de Sistemas y Automática Escuela Técnica Superior de Ingeniería Universidad de Sevilla, 2014. [9]H. Montiel, E. Jacinto y H. Martínez, “Generación de Ruta Óptima para Robots Móviles a Partir de Segmentación de Imágenes,” Información Tecnológica, vol. 26, 2015. [10] C. Expósito, “Los diagramas de Vornooi, la forma matemática de dividir el mundo,” Dialnet, Diciembre 2016. (shrink)

This work presents results of improvement in the productivity of Arthrospira platensis in a company dedicated to its production. The six sigma methodology was applied in production processes that require the use of bioreactors. Starting from the analysis of the current state, aspects, physical and chemical variables that directly influence the productivity achieved were identified. Various culture media were tested and subsequently scaled for industrial production. In addition, the incorporation of carbon into the culture medium was controlled, optimizing the range (...) of potential hydrogen pH. The identified parameters were measured and six sigma methodology strategies were assigned. An improvement in productivity corresponding to 66% was verified with the same quality of final product. Keywords: Six sigma, Bioreactors, Productivity, Arthrospira platensis. References [1]E. Ariawan and A. Makalew, “Smart Micro Farm: Sustainable Algae Spirulina Growth Monitoring System” in 10th International Conference on Information Technology and Electrical Engineering, Bali, 2018, pp.1-4. [2]L. Socconini and C. Reato, Lean six sigma: sistema de gestión para liderar empresas. Primera edición. Barcelona: Marge Books, 2019. [3]H. Gutiérrez, Calidad and productividad. Cuarta edición. México D.F.: McGraw-Hill Interamericana, 2014. [4]G. Usharani, P. Saranraj and D. Kanchana, “Spirulina Cultivation: A Review” in International Journal of Pharmaceutical & Biological Archives, vol. 3, no. 6, pp. 1327-1336, December 2012. [5]J. Udin, O. Gani, A. Mahato, I. Sakib and M. Rakiuzzaman, SPIRULINA PRODUCTION IN DIFFERENT PHOTOBIOREACTORS ON ROOFTOP, International Journal of Business, Social and Scientific Research, vol. 8, no. 1, pp. 15-19, January 2020. [6]M. Arredondo, Contabilidad y análisis de costos. Primera edición. México D.F.: Grupo Editorial Patria, 2015. [7]J. García, Contabilidad de costos. Cuarta edición. México D.F.: McGraw-Hill Interamericana, 2014. [8]L. Socconini, Certificación Lean Six Sigma Green Belt para la excelencia en los negocios. Primera edición. Barcelona: Marge Books, 2015. [9]A. Vian, Introducción a la Química Industrial. Segunda edición. Buenos Aires: Reverté, 2012. [10]S. Milton, Estadística para Biología y Ciencias de la Salud. Tercera edición. Madrid: McGraw-Hill Interamericana, 2014. (shrink)

Bazzocchi disposes the text of the Tractatus in a user-friendly manner, exactly as Wittgenstein's decimals advise. This discloses the logical form of the book by distinct reading units, linked into a fashioned hierarchical tree. The text becomes much clearer and every reader can enjoy, finally, its formal and literary qualities.

The current times call for reforms in educational processes. The Covid-19 pandemic had an unforeseen impact on the educational system in all countries. This need for change requires new pedagogies and new methods for teaching and learning. Understanding the need for change is essential for the formulation of adaptive proposals, as well as for the generation of training activities to complement the teaching curriculum. New educational practices lead to a vision of educational quality, with new approaches that allow the continuous (...) integration of knowledge and permanent interaction with the student. This paper presents an analysis of the new teaching methodologies in times of confinement due to the pandemic caused by Covid-19. Keywords: Teaching methodologies, educational system, learning process. References [1]É. Tremblay-Wragg, C. Raby, L. Ménard y I. Plante, «El uso de estrategias didácticas diversificadas por cuatro profesores universitarios: ¿qué contribución a la motivación de aprendizaje de sus alumnos?,» Docencia en educación superior, vol. 26, nº 21, 2021. [2]L. Czerniewicz, R. Mogliacci, S. Walji, A. Cliff, B. Swinnerton y N. Morris, «Enseñanza y aprendizaje académico en el nexo: desagregación, mercantilización y digitalización en la educación superior,» Teaching in Higher Education, vol. 26, nº 2021, p. 16, 2021. [3]S. Dogan y A. Adam, «Aumentar el efecto del desarrollo profesional en la instrucción efectiva a través de comunidades profesionales,» Docentes y docencia: teoría y práctica, vol. 26, nº 3-4, pp. 326-349, 2020. [4]I. M. Torres Salas, «La enseñanza tradicional de las ciencias versus las nuevas tendencias educativas,» Educare, vol. 14, nº 1, pp. 131-142, 2010. [5]B. Fabio, J. Antonio Palomino y J. González Henríquez, «Evaluación y contraste de los métodos de enseñanza tradicional y lúdico,» Revista de Educación física y deportes, vol. 13, nº 94, pp. 29-36, 2008. [6]Y. Benítez y C. Mora, «Enseñanza tradicional vs aprendizaje activo,» Revista Cubana de Física, vol. 27, nº 2A, pp. 175-179, 2010. [7]P. Morales Bueno y V. Landa Fitzgerald, «Aprendizaje basado en problemas,» Theoria, vol. 13, nº 1, pp. 145-157, 2004. [8]R. Gil-Galván, I. Martín-Espinosa y F. Gil-Galván, «University student perceptions of competences acquired through problem-based learning,» Educación XXI, vol. 24, nº 1, pp. 271-295, 2020. [9]E. Ortiz Cermeño, «El aprendizaje basado en problemas,» Perfiles Educativos, vol. 41, nº 164, pp. 208-213, 2019. [10]E. Araos-Baeriswyl, C. Moll-Manzur, Á. Paredes y J. Landeros, «Aprendizaje invertido: un enfoque pedagógico en tiempos de pandemia,» Rev. Atención Primaria, vol. 53, nº 1, p. 117, 2021. [11]V. León-Carrascosa, M. Belando-Montoro y S. Sánchez-Serrano, «Design and validation of a questionnaire to evaluate the service-learning methodology,» Rev.Estudios sobre educación, vol. 39, nº 1, pp. 247-266, 2020. [12]J. Collado-Ruano, M. Ojeda, M. Malo y D. Amino, «Educación, arte e interculturalidad: El cine documental como lenguaje comunicativo y tecnología innovadora para el aprendizaje de la metodología I + D + I,» Rev. Texto livre, vol. 13, nº 3, pp. 376-393, 2020. [13]P. M. Bueno y V. Landa Fitzgerald, «Aprendizaje basado en problemas,» Theoria, vol. 13, nº 1, pp. 145-157, 2004. [14]J. A. Martí, M. Heydrich, M. Rojas y A. Hernández, «Aprendizaje basado en proyectos: Una experiencia de innovación docente,» Universidad EAFIT, vol. 46, nº 158, pp. 11-21, 2010. [15]L. Rojas y N. M. Jaimes, «Canvas LMS y el trabajo colaborativo como metodología de aprendizaje en entornos virtuales,» de Congreso Ibérico de Sistemas y Tecnologías de la Información, CISTI, Bogotá, Colombia, 2020. [16]B. Bordel y P. Mareca, «Results and Trends in educational MOOCs in the engineering area with MIRIADAX platform. A case study,» de 15th Iberian Conference on Information Systems and Technologies, CISTI 2020; Seville; Sevilla, España, 2020. [17]K. Vermeir y G. Kelchtermans, «Innovative practice as interpretative negotiation.A case-study on the kamishibai in Kindergarten.,» Teachers and Teaching: Theory and Practice, vol. 26, nº 3-4, pp. 248-263, 2020. [18]B. Tucker, «The Flipped Classroom: Online instruction at home frees class time for learning,» Education Next, vol. 1, nº 1, pp. 82-84, 2012. [19]M. V. Ledo, N. R. Michelena, N. N. Cao, I. d. R. M. Suárez y M. N. Vialart Vidal, « Aula invertida, nueva estrategia didáctica,» Educación Médica Superior, vol. 30, nº 3, pp. 678-688, 2016. [20]Metodologías activas por medio de las TIC, [Online]. Available: https://www.campuseducacion.com/blog/recursos/articulos-campuseducacion metodologias-activas-por-medio-de-las-tic/?cn-reloaded=1. [Last access: February 14, 2021]. (shrink)

One of Hume's most well-known works and a masterpiece of philosophy, A Treatise of Human Nature is indubitably worth taking the time to read.

SummaryIntense, sustained nursing lengthens inter-birth intervals and is causally linked with low natural fertility. However, in traditional settings, the effects of such nursing on fertility are difficult to disentangle from those of nutrition. Results from an prospective, direct observational study of reproductive function in well-nourished Amele women who nurse intensively and persistently but who also have high fertility are here presented. Endocrine measures show that ovarian activity resumes by median 11·0 months postpartum. Median duration of postpartum amenorrhoea is 11·3 months, (...) time to next conception is 19·0 months, and the inter-birth interval is 28·0 months. Average life time fertility is 6·8. High fertility in Amele women is due both to refractoriness of reproductive function to suckling stimuli, and to maintenance of equivalent age-specific fertility rates across the reproductive life span. (shrink)

This 1992 book examines alternative methods for achieving optimality without all the apparatus of economic planning, or a vain reliance on sufficiently 'perfect' competition. All rely entirely on the self-interest of economic agents and voluntary contract. The author considers methods involving feedback iterative controls which require the prior selection of a 'criterion function', but no prior calculation of optimal quantities. The target is adjusted as the results for each step become data for the criterion function. Implementation is built in by (...) the incentive structure, and all controls rely on consistency with the self-interest of individuals. The applicability of all the methods is shown to be independent of the form of ownership of enterprises: examples are given for industries which are wholly privately owned, wholly nationalized, mixed and labour-managed. (shrink)

According to the prevailing sentiment, changing the past is logically impossible. The prevailing sentiment is wrong. In this paper, I argue that the claim that changing the past entails a contradiction ultimately rests upon an empirical assumption, and so the conclusion that changing the past is logically impossible is to be resisted. I then present and discuss a model of time which drops the empirical assumption and coherently models changing the past. Finally, I defend the model, and changing the past, (...) against objections. (shrink)

Some philosophers argue that any attempt to model changing the past will either be contradictory or really model avoiding the past. Using Nicholas Smith's (1997) argument as a basis, I formulate a generic version of this Avoidance Argument. I argue that the Avoidance Argument fails because (i) it involves an equivocation of what is meant by ‘bifurcation of the time of an event’ and (ii) resolving the equivocation results in the falsity of at least one of the premises. Hence, the (...) Avoidance Argument will not support the claim that changing the past is logically impossible. (shrink)

The method of interpreting political theory in relation to its specific historical contexts offers particular insight into the work of Karl Marx. When pre-capitalist societies are understood in relation to Marx's rigorously conceived capitalist mode of production, it is apparent that the context in which Marx produced his very earliest work was itself pre-capitalist. It can then be recognized that Marx began by making a significant contribution to an existing framework of critical political theory but also that, following a critical (...) confrontation with English political economy in 1844, he opened new avenues of thought in relation to a new context: capitalism. (shrink)

Quantum mechanics, which describes the behavior of subatomic particles, seems to challenge common sense. Waves behave like particles; particles behave like waves. You can tell where a particle is, but not how fast it is moving--or vice versa. An electron faced with two tiny holes will travel through both at the same time, rather than one or the other. And then there is the enigma of creation ex nihilo, in which small particles appear with their so-called antiparticles, only to disappear (...) the next instant in a tiny puff of energy. Since its inception, physicists and philosophers have struggled to work out the meaning of quantum mechanics. Some, like Niels Bohr, have responded to quantum mechanics' mysteries by replacing notions of position and velocity with probabilities. Others, like Einstein and Penrose, have disagreed and think that the entire puzzle reflects not a fundamental principle of nature but our own ignorance of basic scientific processes. Sneaking a Look at God's Cards offers the general reader a deep and real understanding of the problems inherent to the interpretation of quantum mechanics, from its inception to the present. The book presents a balanced overview of current debates and explores how the theory of quantum mechanics plays itself out in the real world. Written from the perspective of a leading European physicist, the book looks extensively at ideas from both sides of the Atlantic and also considers what philosophers have contributed to the scientific discussion of this field. Sneaking a Look at God's Cards sets out what we know about the endlessly fascinating quantum world, how we came to this understanding, where we disagree, and where we are heading in our quest to comprehend the seemingly incomprehensible. (shrink)

G. C. J. Midgley; XIV—Linguistic Rules, Proceedings of the Aristotelian Society, Volume 59, Issue 1, 1 June 1959, Pages 271–290, https://doi.org/10.1093/aristot.