Assessment of a methodology to mesh the spatial domain in the proximity of the boundary conditions for one-dimensional gas dynamic calculation

[EN] Solution of governing equations for one-dimensional compressible unsteady flow has been performed traditionally using a homogenously distributed spatial mesh. In the resulting node structure, the internal nodes are solved by applying a shock capturing finite difference numerical method whereas the solution of the end nodes, which define the boundary conditions of the pipe, is undertaken by means of the Method of Characteristics. Besides the independent solution of every method, the coupling between the information obtained by the method of characteristics and the finite difference method is key in order to reach a good accuracy in gas dynamics modeling. The classical spatial mesh could provide numerical problems leading the boundary to generate lack of mass, momentum and energy conservation because of the interpolation methodology usually applied to draw the characteristics and path lines from its departure point at calculation time to the end of the pipe during the next time-step. To deal with this undesirable behavior, in this work a modification of the traditional grid including an extra node close to the boundary is proposed in order to explore its ability to provide numerical results with higher conservation fulfillment. © 2010 Elsevier Ltd.J.R. Serrano; Arnau Martínez, FJ.; Piqueras, P.; Reyes Belmonte, MA. (2011). Assessment of a methodology to mesh the spatial domain in the proximity of the boundary conditions for one-dimensional gas dynamic calculation. Mathematical and Computer Modelling. 54:1747-1752. doi:10.1016/j.mcm.2010.11.073S174717525

A Robust Adiabatic Model for a Quasi-Steady Prediction of Far-Off Non-Measured Performance in Vaneless Twin-Entry or Dual-Volute Radial Turbines

[EN] The current investigation describes in detail a mass flow oriented model for extrapolation of reduced mass flow and adiabatic efficiency of double entry radial inflow turbines under any unequal and partial flow admission conditions. The model is based on a novel approach, which proposes assimilating double entry turbines to two variable geometry turbines (VGTs) using the mass flow ratio ( MFR ) between the two entries as the discriminating parameter. With such an innovative approach, the model can extrapolate performance parameters to non-measured MFR s, blade-to-jet speed ratios, and reduced speeds. Therefore, the model can be used in a quasi-steady method for predicting double entry turbines performance instantaneously. The model was validated against a dataset from two different double entry turbine types: a twin-entry symmetrical turbine and a dual-volute asymmetrical turbine. Both were tested under steady flow conditions. The proposed model showed accurate results and a coherent set of fitting parameters with physical meaning, as discussed in this paper. The obtained parameters showed very similar figures for the aforementioned turbine types, which allows concluding that they are an adequate set of values for initializing the fitting procedure of any type of double entry radial turbine.Vishnu Samala is partially supported through contract FPI-2017-S2-1256 of Programa de Apoyo para la Investigacion y Desarrollo (PAID) of Universitat Politecnica de Valencia. This work was partially funded by the 'Ayuda a Primeros Proyectos de Investigacion' (PAID-06-18), Vicerrectorado de Investigacion, Innovacion y Transferencia de la Universitat Politecnica de Valencia (UPV), Valencia, Spain.Serrano, J.; Arnau Martínez, FJ.; García-Cuevas González, LM.; Samala, V. (2020). A Robust Adiabatic Model for a Quasi-Steady Prediction of Far-Off Non-Measured Performance in Vaneless Twin-Entry or Dual-Volute Radial Turbines. Applied Sciences. 10(6):1-43. https://doi.org/10.3390/app10061955S143106Haq, G., & Weiss, M. (2016). CO2 labelling of passenger cars in Europe: Status, challenges, and future prospects. Energy Policy, 95, 324-335. doi:10.1016/j.enpol.2016.04.043Wang, S., Zhao, F., Liu, Z., & Hao, H. (2017). Heuristic method for automakers’ technological strategy making towards fuel economy regulations based on genetic algorithm: A China’s case under corporate average fuel consumption regulation. Applied Energy, 204, 544-559. doi:10.1016/j.apenergy.2017.07.076Kalghatgi, G. (2018). Is it really the end of internal combustion engines and petroleum in transport? Applied Energy, 225, 965-974. doi:10.1016/j.apenergy.2018.05.076Serrano, J. (2017). Imagining the Future of the Internal Combustion Engine for Ground Transport in the Current Context. Applied Sciences, 7(10), 1001. doi:10.3390/app7101001Kruiswyk, R. W. (2012). The role of turbocompound in the era of emissions reduction. 10th International Conference on Turbochargers and Turbocharging, 269-280. doi:10.1533/9780857096135.5.269Yang, M., Deng, K., Martines-Botas, R., & Zhuge, W. (2016). An investigation on unsteadiness of a mixed-flow turbine under pulsating conditions. Energy Conversion and Management, 110, 51-58. doi:10.1016/j.enconman.2015.12.007Zhu, D., & Zheng, X. (2017). Asymmetric twin-scroll turbocharging in diesel engines for energy and emission improvement. Energy, 141, 702-714. doi:10.1016/j.energy.2017.07.173Romagnoli, A., Copeland, C. D., Martinez-Botas, R., Seiler, M., Rajoo, S., & Costall, A. (2012). Comparison Between the Steady Performance of Double-Entry and Twin-Entry Turbocharger Turbines. Journal of Turbomachinery, 135(1). doi:10.1115/1.4006566Serrano, J. R., Arnau, F. J., Gracía-Cuevas, L. M., Samala, V., & Smith, L. (2019). Experimental approach for the characterization and performance analysis of twin entry radial-inflow turbines in a gas stand and with different flow admission conditions. Applied Thermal Engineering, 159, 113737. doi:10.1016/j.applthermaleng.2019.113737Watson, N., & Janota, M. S. (1982). Turbocharging the Internal Combustion Engine. doi:10.1007/978-1-349-04024-7Cerdoun, M., & Ghenaiet, A. (2016). Characterization of a Twin-Entry Radial Turbine under Pulsatile Flow Condition. International Journal of Rotating Machinery, 2016, 1-15. doi:10.1155/2016/4618298Winkler, N., Ångström, H.-E., & Olofsson, U. (2005). Instantaneous On-Engine Twin-Entry Turbine Efficiency Calculations on a Diesel Engine. SAE Technical Paper Series. doi:10.4271/2005-01-3887Fiaschi, D., Lifshitz, A., Manfrida, G., & Tempesti, D. (2014). An innovative ORC power plant layout for heat and power generation from medium- to low-temperature geothermal resources. Energy Conversion and Management, 88, 883-893. doi:10.1016/j.enconman.2014.08.058Zare, V. (2015). A comparative exergoeconomic analysis of different ORC configurations for binary geothermal power plants. Energy Conversion and Management, 105, 127-138. doi:10.1016/j.enconman.2015.07.073Daabo, A. M., Al Jubori, A., Mahmoud, S., & Al-Dadah, R. K. (2016). Parametric study of efficient small-scale axial and radial turbines for solar powered Brayton cycle application. Energy Conversion and Management, 128, 343-360. doi:10.1016/j.enconman.2016.09.060Cheng, Z., Tong, S., & Tong, Z. (2019). Bi-directional nozzle control of multistage radial-inflow turbine for optimal part-load operation of compressed air energy storage. Energy Conversion and Management, 181, 485-500. doi:10.1016/j.enconman.2018.12.014Wei, D., Lu, X., Lu, Z., & Gu, J. (2007). Performance analysis and optimization of organic Rankine cycle (ORC) for waste heat recovery. Energy Conversion and Management, 48(4), 1113-1119. doi:10.1016/j.enconman.2006.10.020Cho, C.-H., Cho, S.-Y., & Ahn, K.-Y. (2010). A study of partial admission characteristics on a small-scale radial-inflow turbine. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, 224(5), 737-748. doi:10.1243/09576509jpe865Cho, S.-Y., Cho, C.-H., Ahn, K.-Y., & Lee, Y. D. (2014). A study of the optimal operating conditions in the organic Rankine cycle using a turbo-expander for fluctuations of the available thermal energy. Energy, 64, 900-911. doi:10.1016/j.energy.2013.11.013Shin, H., Cho, J., Baik, Y.-J., Cho, J., Roh, C., Ra, H.-S., … Huh, J. (2017). Partial Admission, Axial Impulse Type Turbine Design and Partial Admission Radial Turbine Test for SCO2 Cycle. Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy. doi:10.1115/gt2017-64349Ding, Z., Zhuge, W., Zhang, Y., Chen, H., Martinez-Botas, R., & Yang, M. (2017). A one-dimensional unsteady performance model for turbocharger turbines. Energy, 132, 341-355. doi:10.1016/j.energy.2017.04.154Martin, G., Talon, V., Higelin, P., Charlet, A., & Caillol, C. (2009). Implementing Turbomachinery Physics into Data Map-Based Turbocharger Models. SAE International Journal of Engines, 2(1), 211-229. doi:10.4271/2009-01-0310Fang, X., & Dai, Q. (2010). Modeling of turbine mass flow rate performances using the Taylor expansion. Applied Thermal Engineering, 30(13), 1824-1831. doi:10.1016/j.applthermaleng.2010.04.016Romagnoli, A., & Martinez-Botas, R. (2011). Performance prediction of a nozzled and nozzleless mixed-flow turbine in steady conditions. International Journal of Mechanical Sciences, 53(8), 557-574. doi:10.1016/j.ijmecsci.2011.05.003Chiong, M. S., Rajoo, S., Romagnoli, A., Costall, A. W., & Martinez-Botas, R. F. (2014). Integration of meanline and one-dimensional methods for prediction of pulsating performance of a turbocharger turbine. Energy Conversion and Management, 81, 270-281. doi:10.1016/j.enconman.2014.01.043Serrano, J. R., Arnau, F. J., Dolz, V., Tiseira, A., & Cervelló, C. (2008). A model of turbocharger radial turbines appropriate to be used in zero- and one-dimensional gas dynamics codes for internal combustion engines modelling. Energy Conversion and Management, 49(12), 3729-3745. doi:10.1016/j.enconman.2008.06.031Serrano, J. R., Arnau, F. J., García-Cuevas, L. M., Dombrovsky, A., & Tartoussi, H. (2016). Development and validation of a radial turbine efficiency and mass flow model at design and off-design conditions. Energy Conversion and Management, 128, 281-293. doi:10.1016/j.enconman.2016.09.032Serrano, J. R., Arnau, F. J., García-Cuevas, L. M., & Inhestern, L. B. (2019). An innovative losses model for efficiency map fitting of vaneless and variable vaned radial turbines extrapolating towards extreme off-design conditions. Energy, 180, 626-639. doi:10.1016/j.energy.2019.05.062Chiong, M. S., Rajoo, S., Martinez-Botas, R. F., & Costall, A. W. (2012). Engine turbocharger performance prediction: One-dimensional modeling of a twin entry turbine. Energy Conversion and Management, 57, 68-78. doi:10.1016/j.enconman.2011.12.001Costall, A. W., McDavid, R. M., Martinez-Botas, R. F., & Baines, N. C. (2010). Pulse Performance Modeling of a Twin Entry Turbocharger Turbine Under Full and Unequal Admission. Journal of Turbomachinery, 133(2). doi:10.1115/1.4000566Newton, P., Romagnoli, A., Martinez-Botas, R., Copeland, C., & Seiler, M. (2013). A Method of Map Extrapolation for Unequal and Partial Admission in a Double Entry Turbine. Journal of Turbomachinery, 136(6). doi:10.1115/1.4025763Chiong, M. S., Rajoo, S., Romagnoli, A., Costall, A. W., & Martinez-Botas, R. F. (2016). One-dimensional pulse-flow modeling of a twin-scroll turbine. Energy, 115, 1291-1304. doi:10.1016/j.energy.2016.09.041Fredriksson, C. F., Qiu, X., Baines, N. C., Müller, M., Brinkert, N., & Gutmann, C. (2012). Meanline Modeling of Radial Inflow Turbine With Twin-Entry Scroll. Volume 5: Manufacturing Materials and Metallurgy; Marine; Microturbines and Small Turbomachinery; Supercritical CO2 Power Cycles. doi:10.1115/gt2012-69018Macek, J., Zak, Z., & Vitek, O. (2015). Physical Model of a Twin-scroll Turbine with Unsteady Flow. SAE Technical Paper Series. doi:10.4271/2015-01-1718Palenschat, T., Mueller, M., Rajoo, S., Chiong, M. S., Newton, P., Martinez-Botas, R., & Tan, F. X. (2018). Steady-State Experimental and Meanline Study of an Asymmetric Twin-Scroll Turbine at Full and Unequal and Partial Admission Conditions. SAE Technical Paper Series. doi:10.4271/2018-01-0971Brinkert, N., Sumser, S., Weber, S., Fieweger, K., Schulz, A., & Bauer, H.-J. (2012). Understanding the Twin Scroll Turbine: Flow Similarity. Journal of Turbomachinery, 135(2). doi:10.1115/1.4006607Semlitsch, B., Wang, Y., & Mihăescu, M. (2015). Flow effects due to valve and piston motion in an internal combustion engine exhaust port. Energy Conversion and Management, 96, 18-30. doi:10.1016/j.enconman.2015.02.058Serrano, J. R., Tiseira, A., García-Cuevas, L. M., Inhestern, L. B., & Tartoussi, H. (2017). Radial turbine performance measurement under extreme off-design conditions. Energy, 125, 72-84. doi:10.1016/j.energy.2017.02.118Payri, F., Serrano, J. R., Fajardo, P., Reyes-Belmonte, M. A., & Gozalbo-Belles, R. (2012). A physically based methodology to extrapolate performance maps of radial turbines. Energy Conversion and Management, 55, 149-163. doi:10.1016/j.enconman.2011.11.003Xue, Y., Yang, M., Martinez-Botas, R. F., Romagnoli, A., & Deng, K. (2019). Loss analysis of a mix-flow turbine with nozzled twin-entry volute at different admissions. Energy, 166, 775-788. doi:10.1016/j.energy.2018.10.075Serrano, J. R., Navarro, R., García-Cuevas, L. M., & Inhestern, L. B. (2018). Turbocharger turbine rotor tip leakage loss and mass flow model valid up to extreme off-design conditions with high blade to jet speed ratio. Energy, 147, 1299-1310. doi:10.1016/j.energy.2018.01.083Serrano, J. R., Olmeda, P., Arnau, F. J., & Samala, V. (2019). A holistic methodology to correct heat transfer and bearing friction losses from hot turbocharger maps in order to obtain adiabatic efficiency of the turbomachinery. International Journal of Engine Research, 21(8), 1314-1335. doi:10.1177/1468087419834194Harrell, F. E. (2001). Ordinal Logistic Regression. Springer Series in Statistics, 331-343. doi:10.1007/978-1-4757-3462-1_1

Nutritional Status and Risk Factors for Frailty in Community-Dwelling Older People : A Cross-Sectional Study

Objective: This study aims to assess the relationship that frailty has with nutritional status and functional risk factors in community-dwelling older adults. Methods: Cross-sectional study in community-dwelling older people, independent for walking and without impaired cognition. Frailty was assessed by Fried criteria. Nutritional status was analyzed by the Mini Nutritional Assessment Short Form (MNA-SF), biochemical markers (albumin, total proteins, cholesterol, lymphocytes, and hemoglobin); and anthropometric parameters (body mass index [BMI], body fat percentage, handgrip, and perimeters). A comprehensive geriatric assessment analyzed other risk factors: functionality, cognition, falls, comorbidity, polypharmacy, physical activity, and quality of life (QoL). Results: We included 564 elderly people with a mean age of 76.05 (standard deviation 3.97) years; 63.1% (n = 356) were women, and 83.9% (n = 473) were prefrail, and frail. The sample presented high functionality and a nutritional status with a predominance of overweight and obesity. Factors associated with frailty (R2 = 0.43) were age over 75 years (odds ratio [OR] 3.31, 95% confidence interval [CI] 1.76, 6.21; p < 0.001), female gender (OR 2.37, 95% CI 1.24, 4.52; p = 0.009), anemia (OR 2.45, 95% CI 1.19, 5.02; p = 0.015), falls (OR 1.94, 95% CI 1.12, 3.25; p = 0.016) and the fear of falling (OR 4.01: 95% CI 1.76, 9.16; p = 0.001). Performing more than 3 weekly hours of physical activity was found to be a protective factor (OR 0.23, 95% CI 0.15, 0.35; p < 0.001). Conclusions: The relationship between frailty and malnutrition in functionally independent community-dwelling older people is unclear. More studies are needed to know what nutritional markers are related to frailty, cognition, and functionality in order to discriminate the risk factors for community-dwelling older people at risk of malnutrition and dependency

Relationship between the risk of falling and prescribed medication in community-dwelling elderly subjects.

Abstract Introduction: The risk of falling increases with age. A third of the population over 65 has one or more falls per year. Objetive: to know the relationship between drug prescription and falls in the elderly. Materials and Methods: a study was carried out through a community intervention in individuals ≥ 70 years of age. Results: The sample was composed of 249 participants, 160 women (64%), with a mean age of 74.47 years (SD 5.33). During the 12 months prior to the study, the mean of falls per person was 0.5 (SD 0.94), the mean of the risk factors was 2.73 (SD 1.4) and the mean of the medication prescribed was 4.2 (SD 3.0). The percentage of the reduction of falls after the study was 12%. The amount of medication prescribed correlated with the incidence of falls before and after the study, r=0.193, p=0.002 y r2=0.170, p=0.009, respectively. Prior to the study, the individuals who were prescribed beta-blockers and antidepressants, had a fall incidence of 0.74 (SD 1.14) and 1.22 (SD 1.09), respectively, however after the intervention there was no relationship between drug prescription and falls. Conclusions: the fall prevention community program was effective since it prevented the negative effects of medication on falls. An interdisciplinary community intervention reduces the global incidence of falls and the incidence of falls related to some specific medication

Thermo-economic analysis of an oxygen production plant powered by an innovative energy recovery system

[EN] Oxy-fuel combustion is considered an attractive alternative to reduce pollutant emissions, which uses high-purity oxygen mixed instead of air for combustion processes. However, purchasing large amounts of high-purity oxygen may be unprofitable for certain industrial sectors, discouraging its implementation. Considering this, the potential of an oxygen production cycle for factories using oxy-fuel combustion is studied by performing a thermo-economic analysis where high-purity oxygen, electricity, and natural gas prices are considered. Oxygen is produced by membrane means, where mixed ionic-electronic conducting membranes are used, which require high temperatures and pressure gradients to work properly. A set of turbochargers is implemented, chosen by scaling an off-the-shelf model, what introduces an innovative way of waste energy recovering for improving the performance of the cycle. The whole cycle is powered by waste heat from high temperature flue gases, and it is sized for a ceramic manufacturing factory. In this work, two cases are analysed, differentiated by considering additional heating and the vacuum generation method in the oxygen line. The first case exhibits smaller production levels, although better profitability (31¿€t¿1), whereas the second case displays higher production levels and production costs (33¿€t¿1). Both cases are competitive concerning the average price of high-purity oxygen, supposing an average of 50¿€t¿1 in wholesale markets, proving the potential of the proposed alternative for oxygen production.This research work has been supported by Grant PDC2021120821-I00 funded by MCIN/AEI/10.13039/501100011033 and by European Union NextGenerationEU/PRTR. This work has also been supported by Grant UPV-SOLGEN-79674 funded by the Vicerrectorado de Investigacion de la Universitat Politecnica de Valencia (PAID-11-21). The authors want to acknowledge the institution "Conselleria d'Educacio, Investigaci o, Cultura i Esport de la Generalitat Valenciana" and its grant program "Subvenciones para la contratacion de personal investigador de caracter predoctoral" for doctoral studies (ACIF/2020/246) funded by The European Union. Also, this work is part of grant number INNVA1/2021/38 funded by "Agencia Valenciana de la Innovacion (AVI)" and by "ERDF A way of making Europe".Serrano, J.; Arnau Martínez, FJ.; García-Cuevas González, LM.; Gutierrez, FA. (2022). Thermo-economic analysis of an oxygen production plant powered by an innovative energy recovery system. Energy. 255:1-18. https://doi.org/10.1016/j.energy.2022.12441911825

Experimental validation of a quasi-two-dimensional radial turbine model

[EN] This article presents the experimental validation of a quasi-two-dimensional radial turbine model able to be used in turbocharged reciprocating internal combustion engine simulations. A passenger car variable-geometry turbine has been tested under steady and pulsating flow conditions, instrumented with multiple pressure probes, temperature sensors and mass flow sensors. Using the data obtained, a pressure decomposition has been performed. The pressure at the turbine inlet and outlet has been split into forward and backward travelling waves, employing the reflected and transmitted waves to verify the goodness of the model. The experimental results have been used to compare the quasi-two-dimensional radial turbine model as well as a classic one-dimensional model. The quasi-two-dimensional code presents a good degree of correlation with the experimental results, providing better results than the one-dimensional approach, especially when studying the high-frequency spectrum.Pablo Soler is partially supported through contract FPI-2017-S2-1428 of Programa de Apoyo para la Investigación y Desarrollo (PAID) of Universitat Politècnica de València. The authors of this paper wish to thank M.A. Ortiz and V. Ucedo for their invaluable work during the experimental setup and the campaign.Galindo, J.; Arnau Martínez, FJ.; García-Cuevas González, LM.; Soler-Blanco, P. (2018). Experimental validation of a quasi-two-dimensional radial turbine model. International Journal of Engine Research. https://doi.org/10.1177/1468087418788502SKesgin, U. (2005). Effect of turbocharging system on the performance of a natural gas engine. Energy Conversion and Management, 46(1), 11-32. doi:10.1016/j.enconman.2004.02.006Tang, H., Pennycott, A., Akehurst, S., & Brace, C. J. (2014). A review of the application of variable geometry turbines to the downsized gasoline engine. International Journal of Engine Research, 16(6), 810-825. doi:10.1177/1468087414552289Pesiridis, A. (2012). The application of active control for turbocharger turbines. International Journal of Engine Research, 13(4), 385-398. doi:10.1177/1468087411435205Romagnoli, A., & Martinez-Botas, R. (2011). Performance prediction of a nozzled and nozzleless mixed-flow turbine in steady conditions. International Journal of Mechanical Sciences, 53(8), 557-574. doi:10.1016/j.ijmecsci.2011.05.003Payri, F., Serrano, J. R., Fajardo, P., Reyes-Belmonte, M. A., & Gozalbo-Belles, R. (2012). A physically based methodology to extrapolate performance maps of radial turbines. Energy Conversion and Management, 55, 149-163. doi:10.1016/j.enconman.2011.11.003Costall, A. W., McDavid, R. M., Martinez-Botas, R. F., & Baines, N. C. (2010). Pulse Performance Modeling of a Twin Entry Turbocharger Turbine Under Full and Unequal Admission. Journal of Turbomachinery, 133(2). doi:10.1115/1.4000566De Bellis, V., & Marelli, S. (2015). One-dimensional simulations and experimental analysis of a wastegated turbine for automotive engines under unsteady flow conditions. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 229(13), 1801-1816. doi:10.1177/0954407015571672Serrano, J. R., Olmeda, P., Páez, A., & Vidal, F. (2010). An experimental procedure to determine heat transfer properties of turbochargers. Measurement Science and Technology, 21(3), 035109. doi:10.1088/0957-0233/21/3/035109Burke, R. D., Copeland, C. D., Duda, T., & Rayes-Belmote, M. A. (2016). Lumped Capacitance and Three-Dimensional Computational Fluid Dynamics Conjugate Heat Transfer Modeling of an Automotive Turbocharger. Journal of Engineering for Gas Turbines and Power, 138(9). doi:10.1115/1.4032663Olmeda, P., Dolz, V., Arnau, F. J., & Reyes-Belmonte, M. A. (2013). Determination of heat flows inside turbochargers by means of a one dimensional lumped model. Mathematical and Computer Modelling, 57(7-8), 1847-1852. doi:10.1016/j.mcm.2011.11.078Serrano, J., Olmeda, P., Arnau, F., Reyes-Belmonte, M., & Lefebvre, A. (2013). Importance of Heat Transfer Phenomena in Small Turbochargers for Passenger Car Applications. SAE International Journal of Engines, 6(2), 716-728. doi:10.4271/2013-01-0576Aghaali, H., Ångström, H.-E., & Serrano, J. R. (2014). Evaluation of different heat transfer conditions on an automotive turbocharger. International Journal of Engine Research, 16(2), 137-151. doi:10.1177/1468087414524755Serrano, J. R., Olmeda, P., Tiseira, A., García-Cuevas, L. M., & Lefebvre, A. (2013). Theoretical and experimental study of mechanical losses in automotive turbochargers. Energy, 55, 888-898. doi:10.1016/j.energy.2013.04.042Serrano, J. R., Olmeda, P., Tiseira, A., García-Cuevas, L. M., & Lefebvre, A. (2013). Importance of Mechanical Losses Modeling in the Performance Prediction of Radial Turbochargers under Pulsating Flow Conditions. SAE International Journal of Engines, 6(2), 729-738. doi:10.4271/2013-01-0577Galindo, J., Fajardo, P., Navarro, R., & García-Cuevas, L. M. (2013). Characterization of a radial turbocharger turbine in pulsating flow by means of CFD and its application to engine modeling. Applied Energy, 103, 116-127. doi:10.1016/j.apenergy.2012.09.013Hakeem, I., Su, C.-C., Costall, A., & Martinez-Botas, R. F. (2007). Effect of volute geometry on the steady and unsteady performance of mixed-flow turbines. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, 221(4), 535-549. doi:10.1243/09576509jpe314Hu X. An advanced turbocharger model for the internal combustion engine. PhD Thesis, Purdue University, West Lafayette, IN, 2000.King A. A turbocharger unsteady performance model for the GT-power internal combustion engine simulation. PhD Thesis, Purdue University, West Lafayette, IN, 2000.Rajoo, S., & Martinez-Botas, R. (2008). Variable Geometry Mixed Flow Turbine for Turbochargers: An Experimental Study. International Journal of Fluid Machinery and Systems, 1(1), 155-168. doi:10.5293/ijfms.2008.1.1.155Serrano, J. R., Tiseira, A., García-Cuevas, L. M., Inhestern, L. B., & Tartoussi, H. (2017). Radial turbine performance measurement under extreme off-design conditions. Energy, 125, 72-84. doi:10.1016/j.energy.2017.02.118Torregrosa, A. J., Broatch, A., Navarro, R., & García-Tíscar, J. (2014). Acoustic characterization of automotive turbocompressors. International Journal of Engine Research, 16(1), 31-37. doi:10.1177/1468087414562866Leufvén, O., & Eriksson, L. (2014). Measurement, analysis and modeling of centrifugal compressor flow for low pressure ratios. 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Experimental approach for the characterization and performance analysis of twin entry radial-inflow turbines in a gas stand and with different flow admission conditions

[EN] In an internal combustion engine, twin entry turbine operates under different unequal admission conditions by feeding the turbine with a dissimilar amount of flow in each entry for a majority of the time. Despite of the impact on turbine performance, normal characteristic maps of these turbines are usually available only for full admission conditions. The current study investigates the best way of building characteristic maps of twin entry radial inflow turbines working under different admission conditions. The mass flow conditions are varied independently for each entry and results are examined to characterize the turbine performance parameters. The new methodology provides a practical approach regarding the reduced turbine speed; mass flow ratio; pressure ratios and efficiencies of a twin entry turbine. The most important conclusion of this work is the protocol of data analysis itself, which allows systematizing the testing procedure of this type of turbines with different steady flow admission and in quasi-adiabatic conditions. By sorting the experimental data in an orderly manner through proposed analysis, the readers can get benefit of this procedure to calibrate their own quasi-steady models for both: mass flow rate and efficiency; or to build new quasi-steady models with clear merit functions for fitting.Vishnu Samala is partially supported through contract FPI-2017-S2-1256 of Programa de Apoyo para la Investigacion y Desarrollo (PAID) of Universitat Politecnica de Valencia. This work was partially funded by FEDER and Government of Spain through Project TRA2016-79185-R. The authors wish to thank M.A. Ortiz and R. Carrascosa for their invaluable work during the experimental setup and campaign.Serrano, J.; Arnau Martínez, FJ.; García-Cuevas González, LM.; Samala, V.; Smith, L. (2019). Experimental approach for the characterization and performance analysis of twin entry radial-inflow turbines in a gas stand and with different flow admission conditions. Applied Thermal Engineering. 159:1-14. https://doi.org/10.1016/j.applthermaleng.2019.113737S11415

Changes in Salivary amylase and glucose in diabetes : a scoping review

Background and Objective: Diabetes mellitus (DM) is a common long-term disease which can be related with salivary amylase levels. DM has recently been associated with salivary amylase diagnostics that could further impair diagnoses in the diabetic population, as well as being an interesting alternative to traditional methods of determine glucose levels. The main advantage of this method is related to the fact that it is a fast diagnostic method. The DM population experiences changes to their metabolism which affects their salivary parameters, making this an alternative procedure for diagnosis and follow-up of the illness due to the non-invasive nature of salivary analyzes. The objective of this review is to summarize the evidence regarding the changes in salivary amylase and glucose levels, and their relationship with blood markers of glycemic control used in clinical settings such as blood glucose and glycated hemoglobin. The differences in salivary amylase levels depending on the method of saliva collection under fasting or non-fasting conditions. The changes in salivary amylase depends on the type of diabetes, the type of insulin treatment or the quality of glycemic control. Conclusions: Salivary amylase concentration is increased in diabetic patients in most of the studies and salivary glucose concentration in all studies in both fasting and non-fasting (post-prandial) conditions. Salivary amylase and glucose concentration represent potential non-invasive biomarkers to evaluate glycemic control and clinical management of diabetic patients, although it is necessary to evaluate the influence of potential modulating factors such as age, duration diseases, sex and the effects of pharmacological treatments in these outcomes which remained to be elucidated

Adapting an internal combustion engine to oxy-fuel combustion with in-situ oxygen production

[EN] In transport applications, reciprocating internal combustion engines still have important advantages in terms of endurance and refueling time and available infrastructure when compared against fuel cell or battery-based powertrains. Although conventional internal combustion engine configurations produce important amounts of greenhouse gases and pollutant emissions, oxy-fuel combustion can be used to mitigate to a great extent such emissions, mainly producing NOx-free, CO2 and H2O exhaust gases. However, the oxygen needed for the combustion, which is mixed with flue gases before entering the cylinder, has to be stored in an additional tank, which hinders the adoption of this technology. Fortunately, the latest developments in gas separation membranes are starting to produce extremely-high selectivity and high permeability oxygen-separation membranes. Using the waste heat of the exhaust gases to heat up a mixed ionic-electronic conducting membrane, and feeding it with pressurized air, it is possible to produce all the oxygen needed by the combustion process while keeping the whole system compact. This work presents a design of an oxy-fuel combustion engine with in-situ oxygen production. The numerical simulations show also that this concept keeps a competitive brake specific fuel consumption, while the high concentration of CO2 in the exhaust gases facilitates the introduction of carbon sequestration technologies, leading to potentially carbon-neutral internal combustion engines.The authors want to acknowledge the institution "Conselleria d'Educacio, Investigació, Cultura i Esport de la Generalitat Valenciana" and its grant program "Subvenciones para la contratacion de personal investigador de caracter predoctoral" for doctoral studies (ACIF/2020/246) funded by The European Union. This research was partially supported by the institution "Agencia Valenciana de la Innovacion (AVI)" and its grant program "Valorizacion y transferencia de resultados de investigación a las empresas. Línea 1. Valorizacion, transferencia y explotación por las empresas de resultados de I+D. Convocatoria 2021" for project named Demostrador de un motor de oxicombustion con captura de CO2 (DMOCCO2)" INNVA1/2021/38, under the European Regional Development Fund (ERDF) program.Arnau Martínez, FJ.; Novella Rosa, R.; García-Cuevas González, LM.; Gutierrez-Castro, FA. (2021). Adapting an internal combustion engine to oxy-fuel combustion with in-situ oxygen production. American Society of Mechanical Engineers (ASME). 1-12. https://doi.org/10.1115/ICEF2021-67707S11

Fear of Falling Score Is a Predictor of Falls in Community-Dwelling Pre-Frail and Frail Older People

Identifying frail older people at risk of falling is a priority in order to apply preventive strategies. This cross-sectional study included community-dwelling pre-frail and frail people (Fried’s criteria) aged 70 years and older to assess the prevalence of falls and identify screening strategies based on comprehensive geriatric assessments to detect an increased risk of falling and recurrent falling in community-dwelling frail and pre-frail old people. Of the 229 participants, 121 (54.9%) had fallen in the previous 12 months, and 20 of these (16.5%) were recurrent fallers (≥2 falls). A score of 20 points or more on the Falls Efficacy Scale International was predictive of falling (area under the receiver-operating characteristics curve 0.67, 95% confidence interval: 0.61–0.74, p < 0.001) with a sensitivity of 51.7% and a specificity of 73.9%. Polypharmacy, Short Physical Performance Battery score of 8 points or less, and Falls Efficacy Scale International score of 20 points or more show an area under the curve of 0.78 (95% confidence interval: 0.67–0.89, p < 0.001) for recurrent falling.Medicin