723 research outputs found
Long term management of obstructive sleep apnea and its comorbidities
Obstructive sleep apnea (OSA) is a worldwide highly prevalent disease associated with systemic consequences, including excessive sleepiness, impairment of neurocognitive function and daytime performance, including driving ability. The long-term sequelae of OSA include and increase risk for cardiovascular, cerebrovascular and metabolic syndrome disorders that ultimately lead to premature death if untreated. To ensure optimal long-term outcomes, the assessment and management of OSA should be personalized with the involvement of the appropriate specialist. Most studies have demonstrated inmediate improvement in daytime somnolence and quality of life with CPAP and other therapies, but the effect of long-term treatment on mortality is still under debate. Currently, the long-term management of OSA should be based on a) identifying physiological or structural abnormalities that are treatable at the time of patient evaluation and b) comprehensive lifestyle interventions, especially weight-loss interventions, which are associated with improvements in OSA severity, cardiometabolic comorbidities, and quality of life. In long-term management, attention should be paid to the clinical changes related to a potential reoccurrence of OSA symptoms and it is also necessary to monitor throughout the follow up how the main associated comorbidities evolve
Image Processing Application Development: From Rapid Prototyping to SW/HW Co-simulation and Automated Code Generation
Nowadays, the market-place offers quite powerful and low cost reconfigurable hardware devices and a wide range of software tools which find application in the image processing field. However, most of the image processing application designs and their latter deployment on specific hardware devices is still carried out quite costly by hand. This paper presents a new approach to image processing application development, which tackles the historic question of how filling the gap existing between rapid throwaway software designs and final software/hardware implementations. A new graphical component-based tool has been implemented which allows to comprehensively develop this kind of applications, from functional and architectural prototyping stages to software/hardware co-simulation and final code generation. Building this tool has been possible thanks to the synergy that arises from the integration of several of the pre-existent software and hardware image processing libraries and tools.COSIVA (TIC 2000-1765-C03-02),EFTCOR (DPI2002-11583-E), PMPDI-UPCT-2004Escuela Técnica Superior de Ingeniería de Telecomunicació
Correlations for the ignition characteristics of six different fuels and their application to predict ignition delays under transient thermodynami conditions
[EN] The ignition characteristics of six different fuels have been correlated as a function of the temperature, pressure, equivalence ratio and oxygen molar fraction in this investigation. More specifically, the ignition delay referred to cool flames, the high-temperature ignition delay and the critical concentrations and ignition times of HO2 and CH2O have been parameterized for n-dodecane, PRFO, PRF25, PRF50, PRF75 and PRF100. To do so, a wide database of ignition data of the aforementioned fuels has been generated by means of chemical simulations in CHEMKIN, solving a detailed mechanism for PRF mixtures and a reduced mechanism for n-dodecane. In fact, in cylinder engine-like conditions reached in a Rapid Compression Expansion Machine (RCEM) have been replicated. The mathematical correlations have shown a relative deviation around 20% with the database in the low-temperature, low-pressure zone, which is the typical accuracy of usual correlations for the ignition delay. Finally, the ignition delay under transient conditions measured in the RCEM has been predicted by means of different integral methods coupled to both the proposed correlations and the generated database. It has been found that deviations between the predictions obtained with the correlations or with the database are lower than 1%. This means that the correlations are accurate enough to predict the ignition time in spite of showing high deviation with the database, since the low-temperature, low-pressure zone has a minor contribution to the ignition delay.The authors would like to thank different members of the CMT-Motores Termicos team of the Universitat Politecnica de Valencia for their contribution to this work. The authors would also like to thank the Spanish Ministry of Education for financing the PhD. Studies of Dario Lopez-Pintor (grant FPU13/02329). This research has been partially funded by FEDER and the Spanish Government through project TRA2015-67136-R.Desantes, J.; Bermúdez, V.; López, JJ.; López-Pintor, D. (2017). Correlations for the ignition characteristics of six different fuels and their application to predict ignition delays under transient thermodynami conditions. Energy Conversion and Management. 152:124-135. https://doi.org/10.1016/j.enconman.2017.09.030S12413515
Methodology for measuring exhaust aerosol size distributions using an engine test under transient operating conditions
[EN] A study on the sources of variability in the measurement of particle size distribution using a two-stage dilution system and an engine exhaust particle sizer was conducted to obtain a comprehensive and repeatable methodology that can be used to measure the particle size distribution of aerosols emitted by a light-duty diesel engine under transient operating conditions. The paper includes three experimental phases: an experimental validation of the measurement method; an evaluation of the influence of sampling factors, such as dilution system pre-conditioning; and a study of the effects of the dilution conditions, such as the dilution ratio and the dilution air temperature. An examination of the type and degree of influence of each studied factor is presented, recommendations for reducing variability are given and critical parameter values are identified to develop a highly reliable measurement methodology that could be applied to further studies on the effect of engine operating parameters on exhaust particle size distributions. © 2011 IOP Publishing Ltd.The translation of this paper was funded by the Universidad Politecnica de Valencia, Spain.Desantes, J.; Bermúdez, V.; Molina, S.; Linares Rodríguez, WG. (2011). Methodology for measuring exhaust aerosol size distributions using an engine test under transient operating conditions. Measurement Science and Technology. 22(11):1-14. doi:10.1088/0957-0233/22/11/115101S1142211Dobbins, R. A. (2007). Hydrocarbon Nanoparticles Formed in Flames and Diesel Engines. Aerosol Science and Technology, 41(5), 485-496. doi:10.1080/02786820701225820Davidson, C. I., Phalen, R. F., & Solomon, P. A. (2005). Airborne Particulate Matter and Human Health: A Review. Aerosol Science and Technology, 39(8), 737-749. doi:10.1080/02786820500191348McDonald, J. D., Barr, E. B., & White, R. K. (2004). Design, Characterization, and Evaluation of a Small-Scale Diesel Exhaust Exposure System. Aerosol Science and Technology, 38(1), 62-78. doi:10.1080/02786820490247623Brown, D. M., Wilson, M. R., MacNee, W., Stone, V., & Donaldson, K. (2001). Size-Dependent Proinflammatory Effects of Ultrafine Polystyrene Particles: A Role for Surface Area and Oxidative Stress in the Enhanced Activity of Ultrafines. Toxicology and Applied Pharmacology, 175(3), 191-199. doi:10.1006/taap.2001.9240Lighty, J. S., Veranth, J. M., & Sarofim, A. F. (2000). Combustion Aerosols: Factors Governing Their Size and Composition and Implications to Human Health. Journal of the Air & Waste Management Association, 50(9), 1565-1618. doi:10.1080/10473289.2000.10464197Kittelson, D. B. (1998). Engines and nanoparticles. Journal of Aerosol Science, 29(5-6), 575-588. doi:10.1016/s0021-8502(97)10037-4Dockery, D. W., Pope, C. A., Xu, X., Spengler, J. D., Ware, J. H., Fay, M. E., … Speizer, F. E. (1993). An Association between Air Pollution and Mortality in Six U.S. Cities. New England Journal of Medicine, 329(24), 1753-1759. doi:10.1056/nejm199312093292401Sem, G. J. (2002). Design and performance characteristics of three continuous-flow condensation particle counters: a summary. Atmospheric Research, 62(3-4), 267-294. doi:10.1016/s0169-8095(02)00014-5Ankilov, A., Baklanov, A., Colhoun, M., Enderle, K.-H., Gras, J., Julanov, Y., … Zagaynov, V. (2002). Intercomparison of number concentration measurements by various aerosol particle counters. Atmospheric Research, 62(3-4), 177-207. doi:10.1016/s0169-8095(02)00010-8Wiedensohlet, A., Orsini, D., Covert, D. S., Coffmann, D., Cantrell, W., Havlicek, M., … Litchy, M. (1997). Intercomparison Study of the Size-Dependent Counting Efficiency of 26 Condensation Particle Counters. Aerosol Science and Technology, 27(2), 224-242. doi:10.1080/02786829708965469Giechaskiel, B., Ntziachristos, L., & Samaras, Z. (2004). Calibration and modelling of ejector dilutors for automotive exhaust sampling. Measurement Science and Technology, 15(11), 2199-2206. doi:10.1088/0957-0233/15/11/004Cheng, M.-D., Storey, J. M., Wainman, T., & Dam, T. (2002). Impacts of venturi turbulent mixing on the size distributions of sodium chloride and dioctyl-phthalate aerosols. Journal of Aerosol Science, 33(3), 491-502. doi:10.1016/s0021-8502(01)00180-xHueglin, C., Scherrer, L., & Burtscher, H. (1997). An accurate, continuously adjustable dilution system (1:10 to 1:104) for submicron aerosols. Journal of Aerosol Science, 28(6), 1049-1055. doi:10.1016/s0021-8502(96)00485-5Lyyränen, J., Jokiniemi, J., Kauppinen, E. I., Backman, U., & Vesala, H. (2004). Comparison of Different Dilution Methods for Measuring Diesel Particle Emissions. Aerosol Science and Technology, 38(1), 12-23. doi:10.1080/02786820490247579Wong, C. P., Chan, T. L., & Leung, C. W. (2003). Characterisation of diesel exhaust particle number and size distributions using mini-dilution tunnel and ejector–diluter measurement techniques. Atmospheric Environment, 37(31), 4435-4446. doi:10.1016/s1352-2310(03)00571-5Liu, Z. G., Ford, D. C., Vasys, V. N., Chen, D.-R., & Johnson, T. R. (2007). Influence of Engine Operating Conditions on Diesel Particulate Matter Emissions in Relation to Transient and Steady-State Conditions. Environmental Science & Technology, 41(13), 4593-4599. doi:10.1021/es0616229Liu, Z. G., Vasys, V. N., & Kittelson, D. B. (2007). Nuclei-Mode Particulate Emissions and Their Response to Fuel Sulfur Content and Primary Dilution during Transient Operations of Old and Modern Diesel Engines. Environmental Science & Technology, 41(18), 6479-6483. doi:10.1021/es0629007Desantes, J. M., Bermúdez, V., Pastor, J. V., & Fuentes, E. (2004). Methodology for measuring exhaust aerosol size distributions from heavy duty diesel engines by means of a scanning mobility particle sizer. Measurement Science and Technology, 15(10), 2083-2098. doi:10.1088/0957-0233/15/10/019Lapuerta, M., Armas, O., & Gómez, A. (2003). Diesel Particle Size Distribution Estimation from Digital Image Analysis. Aerosol Science and Technology, 37(4), 369-381. doi:10.1080/02786820300970Wiedensohler, A. (1988). An approximation of the bipolar charge distribution for particles in the submicron size range. Journal of Aerosol Science, 19(3), 387-389. doi:10.1016/0021-8502(88)90278-9Wen, H. Y., Reischl, G. P., & Kasper, G. (1984). Bipolar diffusion charging of fibrous aerosol particles—II. charge and electrical mobility measurements on linear chain aggregates. Journal of Aerosol Science, 15(2), 103-122. doi:10.1016/0021-8502(84)90030-2Oh, H., Park, H., & Kim, S. (2004). Effects of Particle Shape on the Unipolar Diffusion Charging of Nonspherical Particles. Aerosol Science and Technology, 38(11), 1045-1053. doi:10.1080/027868290883324Matti Maricq, M. (2007). Chemical characterization of particulate emissions from diesel engines: A review. Journal of Aerosol Science, 38(11), 1079-1118. doi:10.1016/j.jaerosci.2007.08.001Katz, J. L. (1970). Condensation of a Supersaturated Vapor. I. The Homogeneous Nucleation of the n‐Alkanes. The Journal of Chemical Physics, 52(9), 4733-4748. doi:10.1063/1.1673706Burtscher, H. (2005). Physical characterization of particulate emissions from diesel engines: a review. Journal of Aerosol Science, 36(7), 896-932. doi:10.1016/j.jaerosci.2004.12.001Mamakos, A., Ntziachristos, L., & Samaras, Z. (2004). Comparability of particle emission measurements between vehicle testing laboratories: a long way to go. Measurement Science and Technology, 15(9), 1855-1866. doi:10.1088/0957-0233/15/9/02
Sensitivity analysis and validation of a predictive procedure for high and low-temperature ignition delays under engine conditions for n-dodecane using a Rapid Compression-Expansion Machine
[EN] A predictive procedure for cool flames and high-temperature ignition delays based on the accumulation and consumption of chain carriers has been validated for n-dodecane under engine conditions. To do so, an experimental parametric study has been carried out in a Rapid Compression-Expansion Machine, measuring the ignition times for different compression ratios (14 and 19), initial temperatures (from 403 K to 463 K), O-2 molar fractions (from 0.21 to 0.16) and equivalence ratios (from 0.4 to 0.7). The measured ignition delays have been compared to results from chemical kinetic simulations performed in CHEMKIN using a 0-D reactor that replicates the experimental conditions by solving five different chemical kinetic mechanisms, as a way to evaluate the mechanisms accuracy and variability. In general, all chemical kinetic mechanisms are able to accurately replicate the experimental ignition delays, being the mean relative deviation lower than 1.9% and 1.6% for both ignition stages, cool flames and the high-temperature ignition respectively. Furthermore, small differences have been appreciated between mechanisms in terms of ignition delay. Then, the predictive method has been applied using different databases obtained from each mechanism and a sensitivity analysis has been performed in order to evaluate the effects of the selected database on the predicted ignition delay. It has been found that while cool flames seems to be independent on the selected mechanism, the predicted high-temperature ignition delay is very sensitive to the species selected as chain carrier. Thus, if formaldehyde is assumed as ignition tracer, the predicted ignition time can vary up to 3%, while this percent decreases up to 1.3% when hydrogen peroxide takes the role of chain carrier. (C) 2017 Elsevier Ltd. All rights reserved.The authors are grateful to the Generalitat Valenciana for the financial support to acquire the RCEM (references PPC/2013/011 and FEDER Operativo 2007/2013 F07010203PCI00CIMETUPV001). Finally, the authors would like to thank the Spanish Ministry of Education for financing the PhD. Studies of Darío López-Pintor (grant FPU13/02329).Desantes, J.; Bermúdez, V.; López, JJ.; López-Pintor, D. (2017). Sensitivity analysis and validation of a predictive procedure for high and low-temperature ignition delays under engine conditions for n-dodecane using a Rapid Compression-Expansion Machine. Energy Conversion and Management. 145:64-81. https://doi.org/10.1016/j.enconman.2017.04.092S648114
Effects of polyunsaturated fatty acids in diets fed to sows on fatty acids in brain, muscle and skin of their piglets
The aim of this research was to determine fatty acid profiles in piglet brain, skin, and muscle, and in the milk of sows fed fat with different saturation grades during gestation and lactation. At 42 days of gestation, 50 multiparous sows were randomly allocated to one of two treatments, namely a diet containing pork lard (n = 25) and a diet containing soybean oil (n = 25). The fats were provided at 3.6% during gestation and at 4% during lactation. The experimental diets were offered through the weaning of the piglets. The fatty acid profile of the milk was determined fourteen days after parturition. At weaning (21 days postpartum) and seven days later, one of the piglets (n = 64) from 16 sows allocated to each treatment was selected at random to determine fatty acid profiles in brain, skin and muscle. Saturated and monounsaturated fatty acids were higher in the diet with pork lard than in that with soybean oil, in which the polyunsaturated fat content was higher. A higher saturation of fatty acids was found in milk from the sows that consumed pork lard, which contained more saturated fatty acids than the milk from sows that consumed soybean oil. The fatty acid profiles in muscle and skin of the piglets were affected by the diet of the sows. However, the fatty acid profile of the piglets’ brains was not affected by the diet of their mothers.
Keywords: fat saturation, lard, piglet survival, sow feeding, soybean oi
Influence of the subestructure irregularity in highway bridge seismic behaviour
Most of preliminary evaluation methods to accomplish the seismic vulnerability of bridges consider as an evaluation
parameter the substructure irregularity. This parameter is estimated by means of the difference in the length of piers or
through the pier typology, but both evaluated by a subjective form. In this paper the evaluation of the influence of
substructure irregularity is presented. First, a simple and regular bridge, with three piers of equal length and four spans,
is considered as an original structure. Starting from this system, different irregular models were elaborated reducing or
incrementing the length of the central or one of the external piers, in percentages of 25%, 50% and 75%. As a seismic
action, a database of more than 50 earthquakes, registered in the Mexican Pacific Coast, the most seismic hazardous
zone of México, were considered. The selected registers have magnitudes greater than six and important peak ground
accelerations. By means of elastic analyses, the variation between regular and irregular maximum responses in
displacements and internal forces are determined. Of the obtained responses, statistical values as mean and standard
deviation are evaluated. With these values, percentages of difference in the response of irregular bridges were
estimated; these percentages could be included as fragility weights of the irregularity degree in more rigorous
preliminary methods to evaluate the seismic vulnerability of bridges.Postprint (published version
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