Del derribo de ideas al levantamiento de puentes: la Epistemología de las ciencias como criterio organizador de la enseñanza en las ciencias/ Física y Química

After a critical analysis of "isolated conceptual changes", a new form to estructure and organize a course is proposed in concordance with scientific epistemology and the "by research" or "by problem solving" science teaching models. This study suggests a reorientation of spontanous ideas investigations linking them to the development of appropiate teaching /learning sequences.</p

Dynamic tests and adaptive control of a bottoming organic Rankine cycle of IC engine using swash-plate expander

This paper deals with the experimental testing of a bottoming Organic Rankine Cycle (ORC) integrate in a 2 l turbocharged gasoline engine using ethanol as working fluid. The main components of the cycle are a boiler, a condenser, a pump and a swash-plate expander. Both steady and transient tests were performed in three engine operating points to understand the behavior and inertia of the system. Pressure-Volume diagram during these transients were presented and analyzed. Operating parameters of the expander, such as expander speed and boiler power, were shifted. The objective of these tests is to understand the inertia of the system and to have a robust control in all the possible transient tests. New European Driving Cycle was tested with and without the expander because it is supposed to represent the typical usage of a car in Europe. It was used to validate the control of the ORC in realistic dynamic conditions of the engine. The importance of each parameter was analyzed by fixing all the parameters, changing each time one specific value. The main result of this paper is that using a slightly simple and robust control based on adaptive PIDs, the two dynamic effects of an ORC could be taken into account, i.e. high inertia effects (boiler and condenser) and low inertia effects (pump and volumetric expander).This work is part of a research project called "Evaluation of bottoming cycles in IC engines to recover waste heat energies" funded by a National Project of the Spanish Government with reference TRA2013-46408-R. The authors thank also to Raul Lujan and Rafael Carrascosa for their contribution in the testing process. Authors want to acknowledge the "Apoyo para la investigacion y Desarrollo (PAID)" grant for doctoral studies (FPI S2 2015 1067).Torregrosa, AJ.; Galindo, J.; Dolz Ruiz, V.; Royo-Pascual, L.; Haller, R.; Melis, J. (2016). Dynamic tests and adaptive control of a bottoming organic Rankine cycle of IC engine using swash-plate expander. Energy Conversion and Management. 126:168-176. https://doi.org/10.1016/j.enconman.2016.07.078S16817612

Local flow measurements in a turbocharger compressor inlet

[EN] This paper describes an experimental study carried out with the objective of characterizing flow instabilities in turbocharger compressors, specially the distribution of the high-temperature compressed back flow that appears upstream of the impeller at marginal surge conditions. The inlet of a test compressor was fitted with linear and circumferential thermocouple arrays in order to measure the temperature distribution caused by this backflow, whose independence of duct wall temperature was validated through thermographic imaging. Miniaturized pressure probes at the inducer and diffuser showed how pressure spectra varied during the different operating conditions. In-duct acoustic intensity was measured in both the inlet and the outlet to investigate the correlation between a known super synchronous broadband issue known as whoosh noise and the backflow behaviour as characterized by local pressure and temperature. Analysis of the results points to inlet whoosh noise being boosted by this reversed flow but not caused by it, the source probably being located at or downstream of the compressor impeller.This work has been partially supported by Jaguar Land Rover Limited, Abbey Road, Whitley, Coventry CV3 4LF, UK. The equipment used in this work has been partially supported by the Spanish Ministerio de Economía y Competitividad through the grant no DPI2015-70464-R and by FEDER project funds “Dotaciön de infraestructuras científico técnicas para el Centro Integral de Mejora Energética y Medioambiental de Sistemas de Transporte (CiMeT), (FEDER-ICTS-2012-06)” framed in the operational program of unique scientific and technical infrastructure of the Spanish Ministerio de Economía y Competitividad. J. García-Tíscar is partially supported through contract FPI-S2-2015-1530 of the Programa de Apoyo para la Investigación y Desarrollo (PAID) of Universitat Politécnica de Valéncia.Torregrosa, AJ.; Broatch, A.; Margot, XM.; García Tíscar, J.; Narvekar, Y.; Cheung, R. (2017). Local flow measurements in a turbocharger compressor inlet. Experimental Thermal and Fluid Science. 88:542-553. https://doi.org/10.1016/j.expthermflusci.2017.07.007S5425538

A tool for predicting the thermal performance of a diesel engine

This paper presents a thermal network model for the simulation of the transient response of diesel engines. The model was adjusted by using experimental data from a completely instrumented engine run under steady-state and transient conditions. Comparisons between measured and predicted material temperatures over a wide range of engine running conditions show a mean error of 7◦C. The model was then used to predict the thermal behavior of a different engine. Model results were checked against oil and coolant temperatures measured during engine warm-up at constant speed and load, and on a New European Driving Cycle. Results show that the model predicts these temperatures with a maximum error of 3◦C.Torregrosa, AJ.; Olmeda González, PC.; Martín Díaz, J.; Romero Piedrahita, CA. (2011). A tool for predicting the thermal performance of a diesel engine. Heat Transfer Engineering. 32(10):891-904. doi:10.1080/01457632.2011.548639S891904321

Hospitalización pediátrica evitable en la Comunidad Valenciana y Cataluña

ResumenObjetivoEstimar las tasas de hospitalización pediátrica evitable por áreas en la Comunidad Valenciana y sectores en Cataluña, y analizar su relación con el nivel socioeconómico o el desarrollo de la atención primaria.MétodoSe estudiaron las hospitalizaciones pediátricas evitables (0-14 años) a partir del Conjunto Mínimo de Datos Básicos del Alta Hospitalaria de la Comunidad Valenciana y de Cataluña (1993-1994). Las variables a estudio fueron: edad, género, nivel socioeconómico y cobertura del nuevo modelo de atención primaria. Se calcularon las tasas brutas y estandarizadas por edad y se realizó una descripción de su variación en áreas y sectores. Se analizó la relación entre las tasas y las características socioeconómicas y de la atención primaria.ResultadosLas hospitalizaciones pediátricas evitables representaron el 21% de todas las hospitalizaciones pediátricas en la Comunidad Valenciana y el 15% en Cataluña. Las tasas brutas en las áreas de la Comunidad Valenciana oscilaron entre 5,7 y 12,7 en 1993 y 6,6 y 17,8 en 1994. La razón de tasas fue de 2,2 y el coeficiente de variación de 37% en 1993 y de 2,7 y 48% respectivamente, en 1994. En los sectores de Cataluña oscilaron entre 2,7 y 24,3 en 1993 y 1,4 y 23,8 en 1994; la razón de tasas fue de 9 y el coeficiente de variación de 52% en 1993, y de 7 y 42% en 1994 respectivamente. Las diferencias encontradas fueron significativas (p < 0,005). No hubo correlación significativa entre el nivel socioeconómico y desarrollo de la atención primaria y las tasas de hospitalización pediátrica evitable por áreas o sectores.ConclusionesLas hospitalizaciones pediátricas evitables suponen una proporción importante de las hospitalizaciones pediátricas. Existe variación en las tasas de hospitalización pediátrica evitable por áreas y sectores, no asociada a los indicadores de nivel socioeconómico y atención primaria utilizados.SummaryObjectiveTo estimate the rates of avoidable pediatric hospitalization in the health areas of the Valencian Community and health sectors of Catalonia, and to analyze if they are related to socioeconomic level or development of primary care.MethodAvoilable paediatric (0-14 years old) hospitalizations were analyzed using the Minimum Basic Data Set of Hospital Discharge in two Autonomous Regions: the Valencian Community and Catalonia (1993-1994). Variables analyzed included age, gender, socioeconomic level and coverage by the new model of primary care. Crude and standardized rates for age were calculated and the variation in areas and sectors was assessed. The association between rates and socioeconomic and primary care characteristics was analyzed.ResultsAvoidable paediatric hospitalizations represent 21% of all paediatric hospitalizations in the Valencian Community and 15% in Catalonia. Crude rates for Valencian Community ranged between 5.7 and 12.7 in 1993 and 6.6 and 17.8 in 1994; extremal quotient was 2.2 and coefficient of variation 37% in 1993 and 2.7 and 48% respectively in 1994. For Catalonia they ranged between 2.7 and 24.3 in 1993 and 1.4 and 23.8 in 1994; extremal quotient was 9 and coefficient of variation 52% in 1993, and 7 and 42% in 1994 respectively. All these differences were significant (p < 0.005). There was no significant correlation between socieconomic level and development of primary health care and rates of avoidable paediatric hospitalization by health areas or sectors.ConclusionsAvoidable paediatric hospitalization represent a significant proportion of paediatric hospitalizations. There are differences in avoidable paediatric hospitalization rates by health areas and sectors, not associated with socieconomic level and primary care indicators

Measuring turbocharger compressor inlet backflow through particle image velocimetry

[EN] An experimental measurement campaign is presented where particle image velocimetry (PIV) was used in an effort to characterize the velocity field in a turbocharger compressor when unstable operating conditions lead to flow reversing from the diffuser into the inlet pipe. Previous studies have successfully used this and similar techniques, but the most relevant results have been obtained in an open compressor where the backflow can diffuse into the ambient. In this work a glass pipe long enough to confine the full extent of the backflow has been used. Advantage was taken from the fact that this backflow is at higher temperature due to the compression process, enabling a preliminary work where a thermocouple array was used to estimate its maximum length across the compressor map. Using these results as a reference both axial and transversal velocity fields were measured. Issues associated with each one are described, along with relevant results that show how the technique correctly identifies the reversed flow, a conclusion that is supported by the comparison of the velocity average and standard deviation profiles with those of measured temperature.This work has been partially supported by Jaguar Land Rover Limited, Abbey Road, Whitley, Coventry CV3 4LF, UK. The equipment used in this work has been partially supported by the Spanish Ministerio de Economia y Competitividad through grant no DPI2015-70464-R and by FEDER - EU project funds "Dotaciem de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energetica y Medioambiental de Sistemas de Transporte (CiMeT), (FEDER-ICTS-2012-06)" framed in the operational program of unique scientific and technical infrastructure of the Spanish Ministerio de Economia y Competitividad. J. Garcia-Tiscar was partially supported through contract FPI-S22015-1530 of the Programa de Apoyo para la Investigacion y Desarrollo (PAID) of Universitat Politecnica de Valencia.Torregrosa, AJ.; Broatch, A.; Pastor, JV.; Garcia Tiscar, J.; Sharma, RK.; Cheung, R. (2018). Measuring turbocharger compressor inlet backflow through particle image velocimetry. Experimental Thermal and Fluid Science. 99:420-432. https://doi.org/10.1016/j.expthermflusci.2018.08.015S4204329

New consistency index based on inertial operating speed

The occurrence of road crashes depends on several factors, with design consistency (i.e., conformance of highway geometry to drivers' expectations) being one of the most important. A new consistency model for evaluating the performance of tangent-to-curve transitions on two-lane rural roads was developed. This model was based on the inertial consistency index (ICI) defined for each transition. The ICI was calculated at the beginning point of the curve as the difference between the average operating speed on the previous 1-km road segment (inertial operating speed) and the actual operating speed at this point. For the calibration of the ICI and its thresholds, 88 road segments, which included 1,686 tangent-to-curve transitions, were studied. The relationship between those results and the crash rate associated with each transition was analyzed. The results showed that the higher the ICI was, the higher the crash rate; thus, the probability of accidents increased. Similar results were obtained from the study of the relationship between the ICI and the weighted average crash rate of the corresponding group of transitions. A graphical and statistical analysis established that road consistency might be considered good when the ICI was lower than 10 km/h, poor when the ICI was higher than 20 km/h, and fair otherwise. A validation process that considered 20 road segments was performed. The ICI values obtained were highly correlated to the number of crashes that had occurred at the analyzed transitions. Thus, the ICI and its consistency thresholds resulted in a new approach for evaluation of consistency.The authors thank the Center for Studies and Experimentation of Public Works of the Spanish Ministry of Public Works, which partially subsidized the data collection, for obtaining the empirical operating speed profiles used in the validation process. The authors also thank the General Directorate of Public Works of the Infrastructure and Transportation Department of the Valencian government, the Valencian Province Council, and the General Directorate of Traffic of the Ministry of the Interior of the Government of Spain for their cooperation in data gathering.García García, A.; Llopis Castelló, D.; Camacho Torregrosa, FJ.; Pérez Zuriaga, AM. (2013). New consistency index based on inertial operating speed. Transportation Research Record. (2391):105-112. doi:10.3141/2391-10S1051122391Ng, J. C. ., & Sayed, T. (2004). Effect of geometric design consistency on road safety. Canadian Journal of Civil Engineering, 31(2), 218-227. doi:10.1139/l03-090Gibreel, G. M., Easa, S. M., Hassan, Y., & El-Dimeery, I. A. (1999). State of the Art of Highway Geometric Design Consistency. Journal of Transportation Engineering, 125(4), 305-313. doi:10.1061/(asce)0733-947x(1999)125:4(305)Hassan, Y. (2004). Highway Design Consistency: Refining the State of Knowledge and Practice. Transportation Research Record: Journal of the Transportation Research Board, 1881(1), 63-71. doi:10.3141/1881-08Polus, A., & Mattar-Habib, C. (2004). New Consistency Model for Rural Highways and Its Relationship to Safety. Journal of Transportation Engineering, 130(3), 286-293. doi:10.1061/(asce)0733-947x(2004)130:3(286)Cafiso, S., Di Graziano, A., Di Silvestro, G., La Cava, G., & Persaud, B. (2010). Development of comprehensive accident models for two-lane rural highways using exposure, geometry, consistency and context variables. Accident Analysis & Prevention, 42(4), 1072-1079. doi:10.1016/j.aap.2009.12.015Zuriaga, A. M. P., García, A. G., Torregrosa, F. J. C., & D’Attoma, P. (2010). Modeling Operating Speed and Deceleration on Two-Lane Rural Roads with Global Positioning System Data. Transportation Research Record: Journal of the Transportation Research Board, 2171(1), 11-20. doi:10.3141/2171-0

Dynamics of the family of c-iterative methods

In this paper, the dynamics of the family of c-iterative methods for solving nonlinear equations are studied on quadratic polynomials. A singular parameter space is presented to show the complexity of the family. The analysis of the parameter space allows us to find elements of the family that have bad convergence properties and also other ones with very stable behaviour. These schemes correspond to values of c in different small regions of the parameter space.Supported by Ministerio de Ciencia y Tecnologia MTM2011-28636-C02-02. The first and fourth authors were also partially supported by P11B2011-30 (Universitat Jaume I), the second and third authors were also partially supported by Vicerrectorado de Investigacion, Universitat Politecnica de Valencia PAID-06-2010-2285.Campos, B.; Cordero Barbero, A.; Torregrosa Sánchez, JR.; Vindel, P. (2015). Dynamics of the family of c-iterative methods. International Journal of Computer Mathematics. 92(9):1815-1825. https://doi.org/10.1080/00207160.2014.893608S1815182592

Fast Incoherent OFDR Interrogation of FBG Arrays Using Sparse Radio Frequency Responses

[EN] We present two implementations of fast, discrete incoherent optical frequency-domain reflectometers (I-OFDR) for the interrogation of equally spaced fiber Bragg grating (FBG) arrays, based on the determination of the array's radio frequency (RF) response at a sparse number of frequencies. FBG reflectivities are determined by use of the inverse discrete Fourier transform (IDFT) of the sparse RF response, in a dynamic range limited by crosstalk induced by FBG positioning errors. The first implementation employs the complete, vector RF response at a number of frequencies equal to the number N of FBGs in the array. In the second, the introduction of a reference reflector allows for an interrogation using the power (phaseless) RF response in 4N - 1 frequencies. Demodulation based on IDFT leads to total interrogation times determined by the network analyzer scan time, which can be as low as 10 mu s per FBG. Depending on the interrogation technique, electrical bandwidth requirements are 12 GHz in our array with 10-cm separation. We implemented both techniques in a N = 10 array, inducing decays in reflectivity by 10 dB in one or several FBGs. Unambiguous detection of FBG decays was obtained in both interrogation methods. Additional tests performed on the measured reflectivities also show that measurement linearity is preserved in the 10-dB decay range. As discrete I-OFDR systems, the proposed techniques show the possibility to reach compromises between interrogation time and dynamic range or accuracy in reflectivity measurements, using the number of interrogation frequencies and the sensor topology.This work was supported in part by Infraestructura GVA-FEDER operative program 2007-2013 and in part by the Spanish MINECO through Project TEC2017-88029-R. The work of J. Clement Bellido was supported by the GVA VALi+d scholarship ACIF/2016/214. The work of J. Hervas was supported by the Spanish MEC scholarship FPU13/04675.Clement, J.; Hervás-Peralta, J.; Madrigal-Madrigal, J.; Maestre, H.; Torregrosa, G.; Fernandez-Pousa, CR.; Sales Maicas, S. (2018). Fast Incoherent OFDR Interrogation of FBG Arrays Using Sparse Radio Frequency Responses. Journal of Lightwave Technology. 36(19):4393-4400. https://doi.org/10.1109/JLT.2018.2821199S43934400361

King-Type Derivative-Free Iterative Families: Real and Memory Dynamics

A biparametric family of derivative-free optimal iterative methods of order four, for solving nonlinear equations, is presented. From the error equation of this class, different families of iterative schemes with memory can be designed increasing the order of convergence up to six. The real stability analysis of the biparametric family without memory is made on quadratic polynomials, finding areas in the parametric plane with good performance. Moreover, in order to study the real behavior of the parametric class with memory, we associate it with a discrete multidimensional dynamical system. By analyzing the fixed and critical points of its vectorial rational function, we can select those methods with best stability properties